1025:, i.e. it can assume either one of two slightly different shapes, which are in equilibrium with each other. In one form the repressor will bind to the operator DNA with high specificity, and in the other form it has lost its specificity. According to the classical model of induction, binding of the inducer, either allolactose or IPTG, to the repressor affects the distribution of repressor between the two shapes. Thus, repressor with inducer bound is stabilized in the non-DNA-binding conformation. However, this simple model cannot be the whole story, because repressor is bound quite stably to DNA, yet it is released rapidly by addition of inducer. Therefore, it seems clear that an inducer can also bind to the repressor when the repressor is already bound to DNA. It is still not entirely known what the exact mechanism of binding is.
1034:
reinforced by hydrophobic interactions. Additionally, there is an abundance of non-specific DNA sequences to which the repressor can bind. Essentially, any sequence that is not the operator, is considered non-specific. Studies have shown, that without the presence of non-specific binding, induction (or unrepression) of the Lac-operon could not occur even with saturated levels of inducer. It had been demonstrated that, without non-specific binding, the basal level of induction is ten thousand times smaller than observed normally. This is because the non-specific DNA acts as sort of a "sink" for the repressor proteins, distracting them from the operator. The non-specific sequences decrease the amount of available repressor in the cell. This in turn reduces the amount of inducer required to unrepress the system.
1125:(phenyl-Gal) is a substrate for β-galactosidase, but does not inactivate repressor and so is not an inducer. Since wild type cells produce very little β-galactosidase, they cannot grow on phenyl-Gal as a carbon and energy source. Mutants lacking repressor are able to grow on phenyl-Gal. Thus, minimal medium containing only phenyl-Gal as a source of carbon and energy is selective for repressor mutants and operator mutants. If 10 cells of a wild type strain are plated on agar plates containing phenyl-Gal, the rare colonies which grow are mainly spontaneous mutants affecting the repressor. The relative distribution of repressor and operator mutants is affected by the target size. Since the
855:
1246:. Monod was following up on similar studies that had been conducted by other scientists with bacteria and yeast. He found that bacteria grown with two different sugars often displayed two phases of growth. For example, if glucose and lactose were both provided, glucose was metabolized first (growth phase I, see Figure 2) and then lactose (growth phase II). Lactose was not metabolized during the first part of the diauxic growth curve because β-galactosidase was not made when both glucose and lactose were present in the medium. Monod named this phenomenon
1254:
818:(cAMP) is a signal molecule whose prevalence is inversely proportional to that of glucose. It binds to the CAP, which in turn allows the CAP to bind to the CAP binding site (a 16 bp DNA sequence upstream of the promoter on the left in the diagram below, about 60 bp upstream of the transcription start site), which assists the RNAP in binding to the DNA. In the absence of glucose, the cAMP concentration is high and binding of CAP-cAMP to the DNA significantly increases the production of β-galactosidase, enabling the cell to
1557:
3662:
1017:: The gene is turned on. Allolactose inhibits the repressor, allowing the RNA polymerase to bind to the promoter and express the genes, resulting in production of LacZYA. Eventually, the enzymes will digest all of the lactose, until there is no allolactose that can bind to the repressor. The repressor will then bind to the operator, stopping the transcription of the LacZYA genes.
1314:
1073:
965:
262:
403:
1063:
1043:
1368:
does not permit binding of the repressor to inhibit transcription of the structural genes. The operator mutation is dominant. When the operator site where repressor must bind is damaged by mutation, the presence of a second functional site in the same cell makes no difference to expression of genes controlled by the mutant site.
1053:
1273:
signal. A working system requires both a ground transmitter and a receiver in the airplane. Now, suppose that the usual transmitter is broken. This system can be made to work by introduction of a second, functional transmitter. In contrast, he said, consider a bomber with a defective receiver. The behavior of
799:. The repressor binding to the operator interferes with binding of RNAP to the promoter, and therefore mRNA encoding LacZ and LacY is only made at very low levels. When cells are grown in the presence of lactose, however, a lactose metabolite called allolactose, made from lactose by the product of the
1406:
The dominance of operator mutants also suggests a procedure to select them specifically. If regulatory mutants are selected from a culture of wild type using phenyl-Gal, as described above, operator mutations are rare compared to repressor mutants because the target-size is so small. But if instead
1576:
a carbon and energy source as glucose. The cAMP level is related not to intracellular glucose concentration but to the rate of glucose transport, which influences the activity of adenylate cyclase. (In addition, glucose transport also leads to direct inhibition of the lactose permease.) As to why
1398:
This explanation is misleading in an important sense, because it proceeds from a description of the experiment and then explains the results in terms of a model. But in fact, it is often true that the model comes first, and an experiment is fashioned specifically to test the model. Jacob and Monod
1033:
Non-specific binding of the repressor to DNA plays a crucial role in the repression and induction of the Lac-operon. The specific binding site for the Lac-repressor protein is the operator. The non-specific interaction is mediated mainly by charge-charge interactions while binding to the operator is
837:
is transferred via a phosphorylation cascade consisting of the general PTS (phosphotransferase system) proteins HPr and EIA and the glucose-specific PTS proteins EIIA and EIIB, the cytoplasmic domain of the EII glucose transporter. Transport of glucose is accompanied by its phosphorylation by EIIB,
585:
In the case of Lac, wild type cells are Lac and are able to use lactose as a carbon and energy source, while Lac mutant derivatives cannot use lactose. The same three letters are typically used (lower-case, italicized) to label the genes involved in a particular phenotype, where each different gene
1508:
However the lactose metabolism enzymes are made in small quantities in the presence of both glucose and lactose (sometimes called leaky expression) due to the fact that the RNAP can still sometimes bind and initiate transcription even in the absence of CAP. Leaky expression is necessary in order to
1178:
operon. Lactose is galactose-β(1→4)-glucose, whereas allolactose is galactose-β(1→6)-glucose. Lactose is converted to allolactose by β-galactosidase in an alternative reaction to the hydrolytic one. A physiological experiment which demonstrates the role of LacZ in production of the "true" inducer
881:
is a four-part protein, a tetramer, with identical subunits. Each subunit contains a helix-turn-helix (HTH) motif capable of binding to DNA. The operator site where repressor binds is a DNA sequence with inverted repeat symmetry. The two DNA half-sites of the operator together bind to two of the
1367:
If the same experiment is carried out using an operator mutation, a different result is obtained (panel (f)). The phenotype of a cell carrying one mutant and one wild type operator site is that LacZ and LacY are produced even in the absence of the inducer IPTG; because the damaged operator site,
1272:
A conceptual breakthrough of Jacob and Monod was to recognize the distinction between regulatory substances and sites where they act to change gene expression. A former soldier, Jacob used the analogy of a bomber that would release its lethal cargo upon receipt of a special radio transmission or
1135:
is another lactose analog. These inhibit the lacI repressor. At low inducer concentrations, both TMG and IPTG can enter the cell through the lactose permease. However at high inducer concentrations, both analogs can enter the cell independently. TMG can reduce growth rates at high extracellular
1581:
works this way, one can only speculate. All enteric bacteria ferment glucose, which suggests they encounter it frequently. It is possible that a small difference in efficiency of transport or metabolism of glucose v. lactose makes it advantageous for cells to regulate the
1549:) of significantly more copies of LacZ (β-galactosidase, for lactose metabolism) and LacY (lactose permease to transport lactose into the cell). After a delay needed to increase the level of the lactose metabolizing enzymes, the bacteria enter into a new rapid phase of
1187:
can still produce LacY permease when grown with IPTG, a non-hydrolyzable analog of allolactose, but not when grown with lactose. The explanation is that processing of lactose to allolactose (catalyzed by β-galactosidase) is needed to produce the inducer inside the
948:. The intervening DNA loops out from the complex. The redundant nature of the two minor operators suggests that it is not a specific looped complex that is important. One idea is that the system works through tethering; if bound repressor releases from O
1571:
relate to how cAMP levels are coupled to the presence of glucose, and secondly, why the cells should even bother. After lactose is cleaved it actually forms glucose and galactose (easily converted to glucose). In metabolic terms, lactose is just as
1626:
have a range of 100–1000 units, being most sensitive in the high and low parts of this range respectively. Since MacConkey lactose and tetrazolium lactose media both rely on the products of lactose breakdown, they require the presence of both
2586:
370:
When lactose is available but not glucose, then some lactose enters the cell using pre-existing transport protein encoded by lacY. This lactose then combines with the repressor and inactivates it, hence allowing the
621:
genes encoding enzymes, and regulatory genes encoding proteins that affect gene expression. Current usage expands the phenotypic nomenclature to apply to proteins: thus, LacZ is the protein product of the
390:
shuts down lactose permease to prevent transport of lactose into the cell. This dual control mechanism causes the sequential utilization of glucose and lactose in two distinct growth phases, known as
1526:
When glucose is absent, CAP-cAMP binds to a specific DNA site upstream of the promoter and makes a direct protein-protein interaction with RNAP that facilitates the binding of RNAP to the promoter.
865:
functional subunits (red+blue and green+orange) each bind a DNA operator sequence (labeled). These two functional subunits are coupled at the tetramerization region (labeled); thus, tetrameric
1162:(5-bromo-4-chloro-3-indolyl-β-D-galactoside) which is an artificial substrate for B-galactosidase whose cleavage results in galactose and 4-Cl,3-Br indigo thus producing a deep blue color.
1379:
genes and show that the unregulated structural gene(s) is(are) the one(s) next to the mutant operator (panel (g). For example, suppose that one copy is marked by a mutation inactivating
1787:
842:
permease and prevents it from bringing lactose into the cell. Therefore, if both glucose and lactose are present, the transport of glucose blocks the transport of the inducer of the
1530:
The delay between growth phases reflects the time needed to produce sufficient quantities of lactose-metabolizing enzymes. First, the CAP regulatory protein has to assemble on the
913:. These two sites were not found in the early work because they have redundant functions and individual mutations do not affect repression very much. Single mutations to either O
1300:
genes but otherwise normal, is then tested for the regulatory phenotype. In particular, it is determined whether LacZ and LacY are made even in the absence of IPTG (due to the
2597:
1523:
When lactose is present but a preferred carbon source (like glucose) is also present then a small amount of enzyme is produced (Lac repressor is not bound to the operator).
1419:
gene confers a wild type phenotype. In contrast, mutation of one copy of the operator confers a mutant phenotype because it is dominant to the second, wild type copy.
256:
791:). If lactose is missing from the growth medium, the repressor binds very tightly to a short DNA sequence just downstream of the promoter near the beginning of
882:
subunits of the repressor. Although the other two subunits of repressor are not doing anything in this model, this property was not understood for many years.
803:
gene, binds to the repressor, causing an allosteric shift. Thus altered, the repressor is unable to bind to the operator, allowing RNAP to transcribe the
1221:
conserves cellular resources and energy by not making the three Lac proteins when there is no need to metabolize lactose, such as when other sugars like
2115:
952:
momentarily, binding to a minor operator keeps it in the vicinity, so that it may rebind quickly. This would increase the affinity of repressor for O
1264:
Monod then focused his attention on the induction of β-galactosidase formation that occurred when lactose was the sole sugar in the culture medium.
1097:
operon for physiological work. IPTG binds to repressor and inactivates it, but is not a substrate for β-galactosidase. One advantage of IPTG for
2696:
3641:
2842:
2212:
1009:
repressor, so the repressor binds tightly to the operator, which obstructs the RNA polymerase from binding to the promoter, resulting in no
854:
325:
It would be wasteful to produce enzymes when no lactose is available or if a preferable energy source such as glucose were available. The
1086:
operon. These compounds are mainly substituted galactosides, where the glucose moiety of lactose is replaced by another chemical group.
3606:
3179:
3451:
1344:, the resulting phenotype is normal—but lacZ is expressed when exposed to inducer IPTG. Mutations affecting repressor are said to be
1304:
produced by the mutant gene being non-functional). This experiment, in which genes or gene clusters are tested pairwise, is called a
1142:
1056:
726:
repressor) unless some molecule (lactose) is added. Once the repressor is removed, RNAP then proceeds to transcribe all three genes (
3151:
2375:
2342:
2043:
1687:
3194:
3189:
494:
including lactose into the cell using a proton gradient in the same direction. Permease increases the permeability of the cell to
3408:
2177:
operon induction in
Escherichia coli: Systematic comparison of IPTG and TMG induction and influence of the transacetylase LacA".
3046:
674:; that is, they are oriented in the same direction immediately adjacent on the chromosome and are co-transcribed into a single
505:
248:
710:
operon) produces a protein that blocks RNAP from binding to the operator of the operon. This protein can only be removed when
382:
However, in the presence of glucose, regardless of the presence of lactose, the operon will be repressed. This is because the
1459:
921:
have only 2 to 3-fold effects. However, their importance is demonstrated by the fact that a double mutant defective in both O
815:
695:
666:
lactose to the bacterium. The proteins are not produced by the bacterium when lactose is unavailable as a carbon source. The
3585:
1852:
Kennell, David; Riezman, Howard (July 1977). "Transcription and translation initiation frequencies of the
Escherichia coli
1296:
with promoter and operator) could be introduced into a single cell. A culture of such bacteria, which are diploid for the
318:
Note that the number of base pairs in diagram given above are not for scale. There are in fact over 5300 base pairs in the
3436:
1930:
Görke B, Stülke J (August 2008). "Carbon catabolite repression in bacteria: many ways to make the most out of nutrients".
1332:
gene or to the operator, respectively. In panel (e) the complementation test for repressor is shown. If one copy of the
838:
draining the phosphate group from the other PTS proteins, including EIIA. The unphosphorylated form of EIIA binds to the
691:
3652:
2400:
1498:
811:
699:
383:
1352:), and this is explained by the fact that repressor is a small protein which can diffuse in the cell. The copy of the
1328:
genes). Panel (a) shows repression, (b) shows induction by IPTG, and (c) and (d) show the effect of a mutation to the
3689:
3403:
2689:
2304:
1324:
is omitted for simplicity). First, certain haploid states are shown (i.e. the cell carries only a single copy of the
1111:-controlled genes is not a variable in the experiment. IPTG intake is dependent on the action of lactose permease in
722:
operon undergoes is referred to as negative inducible, meaning that the gene is turned off by the regulatory factor (
329:
operon uses a two-part control mechanism to ensure that the cell expends energy producing the enzymes encoded by the
1618:, the colour change from white colonies to a shade of blue corresponds to about 20–100 β-galactosidase units, while
1520:
When lactose is absent then there is very little Lac enzyme production (the operator has Lac repressor bound to it).
3595:
3461:
3293:
2722:
1305:
107:
operon was the first genetic regulatory mechanism to be understood clearly, so it has become a foremost example of
1891:
Malan, T. Philip; Kolb, Annie; Buc, Henri; McClure, William (December 1984). "Mechanism of CRP-cAMP Activation of
1415:), the repressor mutations (which still occur) are not recovered because complementation by the second, wild type
3288:
2919:
2855:
2825:
2803:
1607:
1489:
genes more than ten times lower than normal. Addition of cAMP corrects the low Lac expression characteristic of
483:
376:
228:
139:
1391:
operon that is adjacent to the mutant operator is expressed without IPTG. We say that the operator mutation is
1253:
3684:
3099:
3074:
3041:
2713:
2705:
2628:
761:
663:
1129:
encoding repressor is about 50 times larger than the operator, repressor mutants predominate in the selection.
626:
gene, β-galactosidase. Various short sequences that are not genes also affect gene expression, including the
2159:
3529:
3466:
3441:
3324:
3244:
3094:
3062:
3036:
3020:
2709:
1132:
1122:
834:
830:
731:
387:
379:
is synthesized allowing even more lactose to enter and the enzymes encoded by lacZ and lacA can digest it.
1395:, it is dominant to wild type but affects only the copy of the operon which is immediately adjacent to it.
95:
operon allows for the effective digestion of lactose when glucose is not available through the activity of
3514:
3413:
3398:
3367:
3268:
2929:
2682:
1546:
1258:
255:
3625:
3519:
3446:
3345:
3283:
3278:
3209:
3144:
3113:
3108:
2976:
2878:
1656:
1568:
1502:
1403:
in DNA with the properties of the operator, and then designed their complementation tests to show this.
1217:
regulation in all organisms. The key idea is that proteins are not synthesized when they are not needed—
424:
46:
35:
1213:, but many of the basic regulatory concepts that were discovered by Jacob and Monod are fundamental to
1762:
1737:
3534:
3377:
3372:
3254:
3249:
3236:
3010:
2924:
2890:
2784:
2258:
236:
3630:
2993:
2961:
2847:
2821:
2661:
2247:"A bacterial two-hybrid selection system for studying protein–DNA and protein–protein interactions"
1611:
687:
683:
2061:"Non-specific DNA binding of genome regulating proteins as a biological control mechanism: I. The
1458:
of IPTG and even in strains of the bacterium lacking the repressor or operator. The discovery of
3319:
2762:
2666:
2216:
2151:
1955:
1814:
1383:
so that it can only produce the LacY protein, while the second copy carries a mutation affecting
1082:
A number of lactose derivatives or analogs have been described that are useful for work with the
1022:
776:
432:
420:
240:
208:
176:
454:
96:
767:
The first control mechanism is the regulatory response to lactose, which uses an intracellular
3580:
3564:
3360:
3355:
3264:
3081:
2568:
2517:
2499:
2460:
2452:
2417:
2391:
2371:
2338:
2286:
2194:
2143:
2096:
2039:
2008:
1947:
1912:
1873:
1834:
1712:
1683:
1438:
Explanation of diauxie depended on the characterization of additional mutations affecting the
1241:
1202:
527:
348:
123:
115:
2643:
2026:
Griffiths, Anthony JF; Gelbart, William M.; Miller, Jeffrey H.; Lewontin, Richard C. (1999).
814:(CAP) homodimer to greatly increase production of β-galactosidase in the absence of glucose.
3694:
3590:
3559:
3554:
3509:
3137:
3003:
2986:
2638:
2558:
2548:
2507:
2491:
2444:
2409:
2367:
2360:
2276:
2266:
2186:
2135:
2086:
2076:
1998:
1990:
1939:
1904:
1865:
1826:
1146:
232:
154:
119:
3600:
3504:
3314:
2867:
416:
360:
131:
111:
100:
2674:
2262:
3666:
3077:
3065:
3015:
2563:
2536:
2032:
1994:
1623:
1214:
679:
428:
356:
2624:
2512:
2479:
2413:
2116:"The effect of the lacY gene on the induction of IPTG inducible promoters, studied in
2091:
2060:
2003:
1974:
1556:
1509:
allow for metabolism of some lactose after the glucose source is expended, but before
3678:
3568:
3482:
3350:
3184:
3161:
2779:
2448:
2395:
2281:
2246:
1908:
1869:
1599:
1206:
1198:
878:
675:
337:
173:
166:
127:
2155:
1678:
Griffiths, Anthony J.F.; Wessler, Susan R.; Carroll, Sean B.; Doebley, John (2015).
367:
operon (enzymes and transport proteins) are repressed. (But not completely stopped)
3393:
3214:
3204:
2495:
1959:
1313:
1233:
578:
509:
462:
212:
2190:
1236:, Monod was testing the effects of combinations of sugars as nutrient sources for
678:
mRNA molecule. Transcription of all genes starts with the binding of the enzyme
557:
Three-letter abbreviations are used to describe phenotypes in bacteria including
363:
does take place all the time. The repressor protein is always expressed, but the
3329:
3309:
2966:
2934:
2837:
1619:
1550:
1167:
1149:
and galactose, and is commonly used as a substrate for assay of β-galactosidase
1076:
711:
495:
491:
3661:
3129:
2027:
1704:
1474:
gene could be restored to full activity by the addition of cAMP to the medium.
3273:
3226:
3118:
2812:
2767:
2757:
2752:
2747:
2652:
1817:
RH. (2001). "Transcription activation by catabolite activator protein (CAP)".
1603:
819:
108:
70:
2503:
2456:
1005:: The gene is essentially turned off. There is no allolactose to inhibit the
829:
operon when glucose is present. Glucose is transported into the cell by the
3524:
3492:
3259:
3165:
2774:
2305:"Milestone 2 – A visionary pair : Nature Milestones in gene expression"
2081:
1277:
bomber cannot be changed by introduction of a second, functional aeroplane.
487:
473:
220:
84:
2572:
2421:
2398:(June 1961). "Genetic regulatory mechanisms in the synthesis of proteins".
2290:
2271:
2198:
1951:
1838:
1830:
1716:
1454:, and that, when mutated, result in a decreased level of expression in the
1442:
genes other than those explained by the classical model. Two other genes,
885:
Eventually it was discovered that two additional operators are involved in
2553:
2521:
2464:
2147:
2139:
2100:
2012:
1916:
1139:
Other compounds serve as colorful indicators of β-galactosidase activity.
3487:
3456:
2981:
2971:
1877:
1360:
gene is effectively shut off by protein produced from the second copy of
1151:
2366:. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press. pp.
1943:
1072:
694:
of the genes. Binding of RNA polymerase to the promoter is aided by the
402:
161:
operon occurs at the transcriptional level, by preventing conversion of
3219:
2941:
2808:
2059:
von Hippel, P.H.; Revzin, A.; Gross, C.A.; Wang, A.C. (December 1974).
1247:
1222:
1099:
964:
758:
736:
469:
465:
391:
261:
216:
88:
79:
74:
810:
The second control mechanism is a response to glucose, which uses the
3199:
2737:
1171:
859:
Tetrameric LacI binds two operator sequences and induces DNA looping.
825:
More recently inducer exclusion was shown to block expression of the
743:
734:, so the genes are independently translated. The DNA sequence of the
671:
458:
386:(CAP), required for production of the enzymes, remains inactive, and
150:
66:
807:
genes and thereby leading to higher levels of the encoded proteins.
730:) into mRNA. Each of the three genes on the mRNA strand has its own
718:
gene is known as the lac repressor. The type of regulation that the
122:
classes for this reason. This lactose metabolism system was used by
17:
1107:. Its concentration remains constant and the rate of expression of
714:
binds to it, and inactivates it. The protein that is formed by the
642:. Although it is not strictly standard usage, mutations affecting
2998:
2850:
1615:
1555:
1387:
and can only produce LacZ. In this version, only the copy of the
1159:
1066:
853:
191:
operon can be expressed and their subsequent proteins translated:
184:
2537:"Impact of the solvent capacity constraint on E. coli metabolism"
2435:
Montminy, M. (1997). "Transcriptional regulation by cyclic AMP".
359:. This blocking/ halting is not perfect, and a minimal amount of
3497:
3069:
2899:
2830:
2662:
Staining Whole Mouse
Embryos for β-Galactosidase (lacZ) Activity
1973:
Oehler, S.; Eismann, E. R.; Krämer, H.; Müller-Hill, B. (1990).
1895:
1644:
1538:
1090:
1062:
1046:
1042:
750:
180:
42:
31:
3133:
2678:
1284:
operon, Jacob developed a system by which a second copy of the
1052:
1682:(11 ed.). Freeman, W.H. & Company. pp. 400–412.
702:(CAP, also known as the cAMP receptor protein). However, the
162:
91:
is the preferred carbon source for most enteric bacteria, the
27:
Set genes encoding proteins and enzymes for lactose metabolism
1673:
1671:
1407:
we start with a strain which carries two copies of the whole
936:
repressor is bound simultaneously to both the main operator O
1602:
in a number of bacterial-based selection techniques such as
1312:
1481:
gene encodes adenylate cyclase, which produces cAMP. In a
1158:
Colonies that produce β-galactosidase are turned blue by
1534:
promoter, resulting in an increase in the production of
1485:
mutant, the absence of cAMP makes the expression of the
571:
His (the ability to synthesize the amino acid histidine)
183:
transcript. In this case, when lactose is required as a
1610:
to a specific promoter sequence must be determined. In
1229:
controls certain genes in response to metabolic needs.
586:
is additionally distinguished by an extra letter. The
549:
has 800 bps, with 3 bps corresponding to 1 amino acid.
869:
binds two operator sequences. This allows tetrameric
406:
Structure of lactose and the products of its cleavage.
3650:
2535:
Vazquez A, Beg QK, Demenezes MA, et al. (2008).
1375:
operons to distinguish between the two copies of the
1371:
A more sophisticated version of this experiment uses
1145:
is cleaved to produce the intensely yellow compound,
1466:
led to the demonstration that mutants defective the
1450:, subsequently were identified that mapped far from
179:
that are able to produce multiple proteins from one
134:
knows which enzyme to synthesize. Their work on the
3618:
3547:
3475:
3429:
3422:
3386:
3338:
3302:
3235:
3172:
3090:
3055:
3029:
2954:
2912:
2889:
2866:
2802:
2795:
2730:
2721:
1225:are available. The following section discusses how
2359:
2031:
1598:gene and its derivatives are amenable to use as a
1103:studies is that since it cannot be metabolized by
686:, which binds to a specific DNA binding site, the
1788:"2.6: The lac Operon; CAP site; DNA footprinting"
929:is dramatically de-repressed (by about 70-fold).
187:source for the bacterium, the three genes of the
610:, encoding the lactose repressor—"I" stands for
41:"lac I" redirects here. Not to be confused with
30:"lac Y" redirects here. Not to be confused with
2114:Hansen LH, Knudsen S, Sørensen SJ (June 1998).
1711:, Treasure Island (FL): StatPearls Publishing,
1606:analysis, in which the successful binding of a
1183:cells is the observation that a null mutant of
1093:(IPTG) is frequently used as an inducer of the
783:gene coding for the repressor lies nearby the
3145:
2690:
2335:Operon, a Short History of a Genetic Paradigm
8:
2337:. Berlin: Walter de Gruyter. pp. 7–10.
1703:Sanganeria, Tanisha; Bordoni, Bruno (2024),
822:lactose and release galactose and glucose.
3426:
3152:
3138:
3130:
2799:
2727:
2697:
2683:
2675:
2173:Marbach A, Bettenbrock K (January 2012). "
2627:at the U.S. National Library of Medicine
2562:
2552:
2511:
2478:Botsford, J L; Harman, J G (March 1992).
2280:
2270:
2090:
2080:
2002:
1639:fusion techniques which include only the
662:genes depends on the availability of the
2240:
2238:
2236:
2234:
1643:gene are thus suited to X-gal plates or
1320:This test is illustrated in the figure (
1252:
1071:
1061:
1051:
1041:
963:
401:
269:operon. Top: Repressed, Bottom: Active.
260:
114:. It is often discussed in introductory
3657:
1667:
1340:, but the second copy is wild type for
831:PEP-dependent phosphotransferase system
3642:Index of evolutionary biology articles
2843:Histone acetylation and deacetylation
1280:To analyze regulatory mutants of the
1209:was the common laboratory bacterium,
1174:of lactose and is the inducer of the
7:
1545:mRNA results in the production (see
1399:first imagined that there must be a
1348:to wild type (and that wild type is
1268:Classification of regulatory mutants
508:(LacA), an enzyme that transfers an
347:halts production of the enzymes and
1680:An Introduction to Genetic Analysis
1091:Isopropyl-β-D-thiogalactopyranoside
526:appear to be necessary for lactose
512:from acetyl-CoA to thiogalactoside.
355:operon. It does so by blocking the
243:of lactose into the cell. Finally,
3452:Evolutionary developmental biology
2642:Virtual Cell Animation Collection
2028:"Regulation of the Lactose System"
1995:10.1002/j.1460-2075.1990.tb08199.x
905:) is about +410 bp downstream of O
435:. The three structural genes are:
375:operon to be expressed. Then more
153:in their genome. They also lack a
25:
1356:operon adjacent to the defective
893:) lies about −90 bp upstream of O
577:Sm (resistance to the antibiotic
568:Lac (the ability to use lactose),
3660:
3409:Evolution of sexual reproduction
2449:10.1146/annurev.biochem.66.1.807
2245:Joung J, Ramm E, Pabo C (2000).
2215:. September 2000. Archived from
1193:Development of the classic model
787:operon and is always expressed (
779:in the absence of lactose. The
254:
3047:Archaeal transcription factor B
1979:operon cooperate in repression"
1541:. More available copies of the
1513:expression is fully activated.
336:In the absence of lactose, the
157:. Hence the gene regulation by
145:Most bacterial cells including
69:required for the transport and
3180:Genotype–phenotype distinction
2496:10.1128/MMBR.56.1.100-122.1992
1257:Figure 2: Monod's "bi-phasic"
816:Cyclic adenosine monophosphate
235:which becomes embedded in the
1:
3437:Regulation of gene expression
2437:Annual Review of Biochemistry
2414:10.1016/S0022-2836(61)80072-7
2213:"ONPG (β-Galactosidase) test"
2191:10.1016/j.jbiotec.2011.10.009
1763:"Prokaryotic Gene Expression"
1738:"Prokaryotic Gene Expression"
333:operon only when necessary.
3607:Endless Forms Most Beautiful
3387:Evolution of genetic systems
3195:Gene–environment correlation
3190:Gene–environment interaction
2358:McKnight, Steven L. (1992).
2065:operon: equilibrium aspects"
1975:"The three operators of the
1932:Nature Reviews. Microbiology
1909:10.1016/0022-2836(84)90262-6
1870:10.1016/0022-2836(77)90279-0
1858:Journal of Molecular Biology
1705:"Genetics, Inducible Operon"
1499:catabolite activator protein
1411:region (that is diploid for
1336:genes carries a mutation in
1029:Role of non-specific binding
812:catabolite activator protein
700:catabolite activator protein
670:genes are organized into an
617:One may distinguish between
506:β-galactoside transacetylase
384:catabolite activator protein
357:DNA dependent RNA polymerase
249:β-galactoside transacetylase
3586:Christiane Nüsslein-Volhard
2480:"Cyclic AMP in prokaryotes"
2329:Muller-Hill, Benno (1996).
2038:. New York: W. H. Freeman.
1497:, encodes a protein called
1493:mutants. The second gene,
590:genes encoding enzymes are
3711:
3462:Hedgehog signaling pathway
3339:Developmental architecture
2723:Transcriptional regulation
2362:Transcriptional Regulation
833:. The phosphate group of
706:gene (regulatory gene for
650:, for historical reasons.
40:
29:
3639:
3289:Transgressive segregation
2920:Transcription coregulator
2856:Histone acetyltransferase
2826:Histone methyltransferase
2804:Histone-modifying enzymes
2637:operon in NCBI Bookshelf
1736:McClean, Phillip (1997).
1608:transcriptional activator
757:genes are available from
486:(LacY), a transmembrane
457:(LacZ), an intracellular
211:which cleaves lactose, a
140:Nobel Prize in Physiology
2629:Medical Subject Headings
2179:Journal of Biotechnology
1590:Use in molecular biology
1423:Regulation by cyclic AMP
775:to hinder production of
658:Specific control of the
3467:Notch signaling pathway
3442:Gene regulatory network
3325:Dual inheritance theory
3021:Internal control region
2657:Operon: Bozeman Science
2484:Microbiological Reviews
2122:Pseudomonas fluorescens
2082:10.1073/pnas.71.12.4808
2034:Modern Genetic Analysis
1624:MacConkey lactose media
1292:with its promoter, and
732:Shine-Dalgarno sequence
574:Mot (swimming motility)
3515:cis-regulatory element
3423:Control of development
3303:Non-genetic influences
3269:evolutionary landscape
2670:Operon Model Explained
2596:. SAPS. Archived from
2272:10.1073/pnas.110149297
2251:Proc Natl Acad Sci USA
1831:10.1006/jmbi.1999.3161
1564:
1317:
1261:
1133:Thiomethyl galactoside
1079:
1069:
1059:
1049:
1018:
960:Mechanism of induction
932:In the current model,
901:gene, and the other (O
874:
873:to induce DNA looping.
484:β-galactoside permease
407:
377:β-galactoside permease
315:
229:β-galactoside permease
203:. The gene product of
172:Bacterial operons are
3626:Nature versus nurture
3530:Cell surface receptor
3447:Evo-devo gene toolkit
3346:Developmental biology
3284:Polygenic inheritance
3210:Quantitative genetics
3114:Intrinsic termination
2879:DNA methyltransferase
2554:10.1186/1752-0509-2-7
2140:10.1007/s002849900320
1657:Catabolite repression
1569:catabolite repression
1559:
1503:cAMP receptor protein
1316:
1256:
1075:
1065:
1055:
1045:
967:
909:in the early part of
857:
415:operon consists of 3
405:
264:
3535:Transcription factor
3250:Genetic assimilation
3237:Genetic architecture
2891:Chromatin remodeling
1586:operon in this way.
1307:complementation test
1123:Phenyl-β-D-galactose
1021:The repressor is an
553:Genetic nomenclature
138:operon won them the
3631:Morphogenetic field
3548:Influential figures
2848:Histone deacetylase
2838:Histone demethylase
2822:Histone methylation
2263:2000PNAS...97.7382J
2162:on 18 October 2000.
1944:10.1038/nrmicro1932
889:regulation. One (O
850:Repressor structure
835:phosphoenolpyruvate
684:DNA-binding protein
646:are referred to as
130:to determine how a
3690:Bacterial genetics
3320:Genomic imprinting
2603:on 20 January 2022
2591:operon in E. coli"
2587:"Induction of the
2219:on 3 November 2007
1792:Biology LibreTexts
1614:plates containing
1565:
1318:
1262:
1080:
1070:
1060:
1050:
1023:allosteric protein
1019:
1013:mRNA transcripts.
972:: RNA Polymerase,
897:in the end of the
875:
769:regulatory protein
564:Examples include:
408:
349:transport proteins
316:
274:: RNA polymerase,
241:cellular transport
3648:
3647:
3581:Eric F. Wieschaus
3543:
3542:
3361:Pattern formation
3265:Fitness landscape
3127:
3126:
3082:RNA polymerase II
2950:
2949:
2908:
2907:
2644:Introducing: The
1470:gene but not the
1302:lactose repressor
1197:The experimental
773:lactose repressor
528:catabolic pathway
461:that cleaves the
16:(Redirected from
3702:
3665:
3664:
3656:
3591:William McGinnis
3560:Richard Lewontin
3555:C. H. Waddington
3427:
3404:Neutral networks
3154:
3147:
3140:
3131:
3004:Response element
2987:Response element
2800:
2728:
2699:
2692:
2685:
2676:
2613:
2612:
2610:
2608:
2602:
2595:
2583:
2577:
2576:
2566:
2556:
2532:
2526:
2525:
2515:
2475:
2469:
2468:
2432:
2426:
2425:
2388:
2382:
2381:
2365:
2355:
2349:
2348:
2326:
2320:
2319:
2317:
2315:
2301:
2295:
2294:
2284:
2274:
2242:
2229:
2228:
2226:
2224:
2209:
2203:
2202:
2170:
2164:
2163:
2158:. Archived from
2118:Escherichia coli
2111:
2105:
2104:
2094:
2084:
2056:
2050:
2049:
2037:
2023:
2017:
2016:
2006:
1983:The EMBO Journal
1970:
1964:
1963:
1927:
1921:
1920:
1888:
1882:
1881:
1849:
1843:
1842:
1810:
1804:
1803:
1801:
1799:
1794:. 3 January 2019
1784:
1778:
1777:
1775:
1773:
1759:
1753:
1752:
1750:
1748:
1733:
1727:
1726:
1725:
1723:
1700:
1694:
1693:
1675:
1635:genes. The many
1563:operon in detail
1435:
1434:
1430:
1147:orthonitrophenol
417:structural genes
258:
233:membrane protein
155:nuclear membrane
120:cellular biology
85:enteric bacteria
21:
3710:
3709:
3705:
3704:
3703:
3701:
3700:
3699:
3685:Gene expression
3675:
3674:
3671:
3659:
3651:
3649:
3644:
3635:
3614:
3601:Sean B. Carroll
3539:
3471:
3418:
3382:
3334:
3315:Maternal effect
3298:
3231:
3168:
3158:
3128:
3123:
3098:
3092:
3086:
3051:
3025:
2946:
2904:
2885:
2868:DNA methylation
2862:
2806:
2791:
2717:
2703:
2621:
2616:
2606:
2604:
2600:
2593:
2585:
2584:
2580:
2534:
2533:
2529:
2477:
2476:
2472:
2434:
2433:
2429:
2390:
2389:
2385:
2378:
2357:
2356:
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2328:
2327:
2323:
2313:
2311:
2303:
2302:
2298:
2244:
2243:
2232:
2222:
2220:
2211:
2210:
2206:
2172:
2171:
2167:
2128:Curr. Microbiol
2113:
2112:
2108:
2075:(12): 4808–12.
2058:
2057:
2053:
2046:
2025:
2024:
2020:
1972:
1971:
1967:
1929:
1928:
1924:
1890:
1889:
1885:
1851:
1850:
1846:
1812:
1811:
1807:
1797:
1795:
1786:
1785:
1781:
1771:
1769:
1761:
1760:
1756:
1746:
1744:
1735:
1734:
1730:
1721:
1719:
1702:
1701:
1697:
1690:
1677:
1676:
1669:
1665:
1653:
1647:liquid broths.
1592:
1567:Two puzzles of
1436:
1432:
1428:
1426:
1425:
1270:
1195:
1136:concentrations.
1040:
1038:Lactose analogs
1031:
962:
955:
951:
947:
943:
940:and to either O
939:
928:
924:
920:
916:
908:
904:
896:
892:
852:
777:β-galactosidase
656:
555:
455:β-galactosidase
400:
361:gene expression
351:encoded by the
270:
237:Plasma membrane
209:β-galactosidase
132:biological cell
112:gene regulation
101:Gene regulation
97:β-galactosidase
83:and many other
50:
39:
28:
23:
22:
15:
12:
11:
5:
3708:
3706:
3698:
3697:
3692:
3687:
3677:
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3669:
3646:
3645:
3640:
3637:
3636:
3634:
3633:
3628:
3622:
3620:
3616:
3615:
3613:
3612:
3611:
3610:
3598:
3593:
3588:
3583:
3578:
3577:
3576:
3565:François Jacob
3562:
3557:
3551:
3549:
3545:
3544:
3541:
3540:
3538:
3537:
3532:
3527:
3522:
3517:
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3336:
3335:
3333:
3332:
3327:
3322:
3317:
3312:
3306:
3304:
3300:
3299:
3297:
3296:
3294:Sequence space
3291:
3286:
3281:
3276:
3271:
3262:
3257:
3252:
3247:
3241:
3239:
3233:
3232:
3230:
3229:
3224:
3223:
3222:
3212:
3207:
3202:
3197:
3192:
3187:
3182:
3176:
3174:
3170:
3169:
3159:
3157:
3156:
3149:
3142:
3134:
3125:
3124:
3122:
3121:
3116:
3111:
3105:
3103:
3088:
3087:
3085:
3084:
3078:RNA polymerase
3072:
3066:RNA polymerase
3059:
3057:
3053:
3052:
3050:
3049:
3044:
3039:
3033:
3031:
3027:
3026:
3024:
3023:
3018:
3013:
3008:
3007:
3006:
3001:
2991:
2990:
2989:
2984:
2979:
2974:
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2896:
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2859:
2858:
2853:
2840:
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2834:
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2818:
2816:
2797:
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2790:
2789:
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2772:
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2770:
2765:
2760:
2755:
2750:
2745:
2734:
2732:
2725:
2719:
2718:
2704:
2702:
2701:
2694:
2687:
2679:
2673:
2672:
2664:
2659:
2650:
2640:
2632:
2620:
2619:External links
2617:
2615:
2614:
2578:
2527:
2490:(1): 100–122.
2470:
2427:
2383:
2376:
2350:
2343:
2321:
2309:www.nature.com
2296:
2257:(13): 7382–7.
2230:
2204:
2165:
2106:
2051:
2044:
2018:
1989:(4): 973–979.
1965:
1922:
1903:(4): 881–909.
1883:
1844:
1825:(2): 199–213.
1805:
1779:
1754:
1728:
1695:
1688:
1666:
1664:
1661:
1660:
1659:
1652:
1649:
1591:
1588:
1528:
1527:
1524:
1521:
1424:
1421:
1269:
1266:
1203:François Jacob
1194:
1191:
1190:
1189:
1165:
1164:
1163:
1156:
1137:
1130:
1120:
1113:P. fluorescens
1039:
1036:
1030:
1027:
961:
958:
953:
949:
945:
941:
937:
926:
922:
918:
914:
906:
902:
894:
890:
851:
848:
690:, immediately
680:RNA polymerase
655:
652:
602:. The fourth
583:
582:
575:
572:
569:
554:
551:
541:has 3000 bps,
537:has 1100 bps,
516:
515:
514:
513:
499:
496:β-galactosides
492:β-galactosides
477:
399:
396:
239:to enable the
124:François Jacob
65:operon) is an
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
3707:
3696:
3693:
3691:
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3570:
3569:Jacques Monod
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3491:
3489:
3486:
3484:
3483:Homeotic gene
3481:
3480:
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3357:
3354:
3353:
3352:
3351:Morphogenesis
3349:
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3344:
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3208:
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3185:Reaction norm
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2970:
2968:
2965:
2964:
2963:
2960:
2959:
2957:
2953:
2943:
2940:
2936:
2933:
2931:
2928:
2926:
2923:
2922:
2921:
2918:
2917:
2915:
2911:
2901:
2898:
2897:
2895:
2892:
2888:
2880:
2877:
2876:
2875:
2874:
2872:
2869:
2865:
2857:
2854:
2852:
2849:
2846:
2845:
2844:
2841:
2839:
2836:
2832:
2829:
2828:
2827:
2823:
2820:
2819:
2817:
2814:
2810:
2805:
2801:
2798:
2794:
2786:
2785:trp repressor
2783:
2781:
2780:lac repressor
2778:
2777:
2776:
2773:
2769:
2766:
2764:
2761:
2759:
2756:
2754:
2751:
2749:
2746:
2744:
2741:
2740:
2739:
2736:
2735:
2733:
2729:
2726:
2724:
2720:
2715:
2711:
2707:
2706:Transcription
2700:
2695:
2693:
2688:
2686:
2681:
2680:
2677:
2671:
2669:
2665:
2663:
2660:
2658:
2656:
2651:
2649:
2647:
2641:
2639:
2636:
2633:
2630:
2626:
2623:
2622:
2618:
2599:
2592:
2590:
2582:
2579:
2574:
2570:
2565:
2560:
2555:
2550:
2546:
2542:
2541:BMC Syst Biol
2538:
2531:
2528:
2523:
2519:
2514:
2509:
2505:
2501:
2497:
2493:
2489:
2485:
2481:
2474:
2471:
2466:
2462:
2458:
2454:
2450:
2446:
2442:
2438:
2431:
2428:
2423:
2419:
2415:
2411:
2408:(3): 318–56.
2407:
2403:
2402:
2397:
2393:
2387:
2384:
2379:
2377:0-87969-410-6
2373:
2369:
2364:
2363:
2354:
2351:
2346:
2344:3-11-014830-7
2340:
2336:
2332:
2325:
2322:
2310:
2306:
2300:
2297:
2292:
2288:
2283:
2278:
2273:
2268:
2264:
2260:
2256:
2252:
2248:
2241:
2239:
2237:
2235:
2231:
2218:
2214:
2208:
2205:
2200:
2196:
2192:
2188:
2184:
2180:
2176:
2169:
2166:
2161:
2157:
2153:
2149:
2145:
2141:
2137:
2133:
2129:
2125:
2123:
2119:
2110:
2107:
2102:
2098:
2093:
2088:
2083:
2078:
2074:
2070:
2066:
2064:
2055:
2052:
2047:
2045:0-7167-3118-5
2041:
2036:
2035:
2029:
2022:
2019:
2014:
2010:
2005:
2000:
1996:
1992:
1988:
1984:
1980:
1978:
1969:
1966:
1961:
1957:
1953:
1949:
1945:
1941:
1938:(8): 613–24.
1937:
1933:
1926:
1923:
1918:
1914:
1910:
1906:
1902:
1898:
1894:
1887:
1884:
1879:
1875:
1871:
1867:
1863:
1859:
1855:
1848:
1845:
1840:
1836:
1832:
1828:
1824:
1820:
1816:
1809:
1806:
1793:
1789:
1783:
1780:
1768:
1764:
1758:
1755:
1743:
1739:
1732:
1729:
1718:
1714:
1710:
1706:
1699:
1696:
1691:
1689:9781464109485
1685:
1681:
1674:
1672:
1668:
1662:
1658:
1655:
1654:
1650:
1648:
1646:
1642:
1638:
1634:
1630:
1625:
1621:
1617:
1613:
1609:
1605:
1601:
1600:reporter gene
1597:
1589:
1587:
1585:
1580:
1575:
1570:
1562:
1558:
1554:
1552:
1548:
1544:
1540:
1537:
1533:
1525:
1522:
1519:
1518:
1517:
1514:
1512:
1506:
1504:
1500:
1496:
1492:
1488:
1484:
1480:
1475:
1473:
1469:
1465:
1461:
1457:
1453:
1449:
1445:
1441:
1431:
1422:
1420:
1418:
1414:
1410:
1404:
1402:
1396:
1394:
1390:
1386:
1382:
1378:
1374:
1369:
1365:
1363:
1359:
1355:
1351:
1347:
1343:
1339:
1335:
1331:
1327:
1323:
1315:
1311:
1309:
1308:
1303:
1299:
1295:
1291:
1287:
1283:
1278:
1276:
1267:
1265:
1260:
1255:
1251:
1249:
1245:
1244:
1239:
1235:
1230:
1228:
1224:
1220:
1216:
1212:
1208:
1207:Jacques Monod
1204:
1200:
1199:microorganism
1192:
1186:
1182:
1177:
1173:
1169:
1166:
1161:
1157:
1154:
1153:
1148:
1144:
1141:
1140:
1138:
1134:
1131:
1128:
1124:
1121:
1118:
1115:, but not in
1114:
1110:
1106:
1102:
1101:
1096:
1092:
1089:
1088:
1087:
1085:
1078:
1074:
1068:
1064:
1058:
1054:
1048:
1044:
1037:
1035:
1028:
1026:
1024:
1016:
1012:
1008:
1004:
1001:
999:
995:
991:
987:
983:
979:
976:: Repressor,
975:
971:
966:
959:
957:
935:
930:
912:
900:
888:
883:
880:
879:lac repressor
872:
868:
864:
860:
856:
849:
847:
845:
841:
836:
832:
828:
823:
821:
817:
813:
808:
806:
802:
798:
794:
790:
786:
782:
778:
774:
770:
765:
763:
760:
756:
752:
749:
745:
742:
739:
738:
733:
729:
725:
721:
717:
713:
709:
705:
701:
697:
693:
689:
685:
681:
677:
676:polycistronic
673:
669:
665:
661:
653:
651:
649:
645:
641:
637:
633:
629:
625:
620:
615:
613:
609:
605:
601:
597:
593:
589:
580:
576:
573:
570:
567:
566:
565:
562:
560:
552:
550:
548:
545:has 800 bps,
544:
540:
536:
531:
529:
525:
521:
511:
507:
503:
500:
497:
493:
489:
485:
481:
478:
475:
471:
467:
464:
460:
456:
452:
449:
448:
446:
442:
438:
434:
430:
426:
422:
418:
414:
410:
409:
404:
397:
395:
393:
389:
385:
380:
378:
374:
368:
366:
362:
358:
354:
350:
346:
343:, encoded by
342:
340:
334:
332:
328:
323:
321:
313:
309:
305:
301:
297:
293:
289:
285:
281:
278:: Repressor,
277:
273:
268:
263:
259:
257:
252:
250:
246:
242:
238:
234:
230:
226:
222:
218:
214:
210:
206:
202:
198:
194:
190:
186:
182:
178:
175:
174:polycistronic
170:
168:
164:
160:
156:
152:
148:
143:
141:
137:
133:
129:
128:Jacques Monod
125:
121:
117:
113:
110:
106:
102:
98:
94:
90:
86:
82:
81:
76:
72:
68:
64:
63:
58:
56:
48:
44:
37:
33:
19:
3672:
3605:
3573:
3498:eyeless gene
3394:Evolvability
3368:Segmentation
3245:Canalisation
3215:Heterochrony
3205:Heritability
3173:Key concepts
2742:
2667:
2654:
2645:
2634:
2605:. Retrieved
2598:the original
2588:
2581:
2544:
2540:
2530:
2487:
2483:
2473:
2440:
2436:
2430:
2405:
2399:
2386:
2361:
2353:
2334:
2330:
2324:
2312:. Retrieved
2308:
2299:
2254:
2250:
2221:. Retrieved
2217:the original
2207:
2185:(1): 82–88.
2182:
2178:
2174:
2168:
2160:the original
2134:(6): 341–7.
2131:
2127:
2121:
2117:
2109:
2072:
2068:
2062:
2054:
2033:
2021:
1986:
1982:
1976:
1968:
1935:
1931:
1925:
1900:
1897:J. Mol. Biol
1896:
1892:
1886:
1861:
1857:
1853:
1847:
1822:
1819:J. Mol. Biol
1818:
1808:
1796:. Retrieved
1791:
1782:
1770:. Retrieved
1766:
1757:
1745:. Retrieved
1741:
1731:
1720:, retrieved
1708:
1698:
1679:
1640:
1636:
1632:
1628:
1622:lactose and
1595:
1593:
1583:
1578:
1573:
1566:
1560:
1542:
1535:
1531:
1529:
1516:In summary:
1515:
1510:
1507:
1494:
1490:
1486:
1482:
1478:
1476:
1471:
1467:
1463:
1455:
1451:
1447:
1443:
1439:
1437:
1416:
1412:
1408:
1405:
1400:
1397:
1393:cis-dominant
1392:
1388:
1384:
1380:
1376:
1372:
1370:
1366:
1361:
1357:
1353:
1349:
1345:
1341:
1337:
1333:
1329:
1325:
1321:
1319:
1306:
1301:
1297:
1293:
1289:
1285:
1281:
1279:
1274:
1271:
1263:
1259:growth curve
1242:
1237:
1234:World War II
1231:
1226:
1218:
1210:
1196:
1184:
1180:
1175:
1150:
1126:
1116:
1112:
1108:
1104:
1098:
1094:
1083:
1081:
1032:
1020:
1014:
1010:
1006:
1002:
997:
993:
989:
985:
984:: Operator,
981:
980:: Promoter,
977:
973:
969:
968:
933:
931:
910:
898:
886:
884:
876:
870:
866:
862:
861:Two dimeric
858:
843:
839:
826:
824:
809:
804:
800:
797:lac operator
796:
792:
789:constitutive
788:
784:
780:
772:
768:
766:
754:
747:
740:
735:
727:
723:
719:
715:
707:
703:
667:
659:
657:
647:
643:
639:
635:
631:
627:
623:
618:
616:
612:inducibility
611:
607:
603:
599:
595:
591:
587:
584:
579:streptomycin
563:
558:
556:
546:
542:
538:
534:
533:By numbers,
532:
523:
519:
517:
510:acetyl group
501:
479:
463:disaccharide
450:
444:
440:
436:
412:
381:
372:
369:
364:
352:
344:
338:
335:
330:
326:
324:
319:
317:
311:
307:
303:
299:
295:
291:
287:
286:: Operator,
283:
282:: Promoter,
279:
275:
271:
266:
253:
244:
224:
213:disaccharide
204:
200:
196:
192:
188:
171:
158:
146:
144:
135:
104:
92:
78:
61:
60:
54:
53:
51:
3596:Mike Levine
3505:Distal-less
3330:Polyphenism
3310:Epigenetics
3162:development
3091:Termination
2967:Pribnow box
2935:Corepressor
2930:Coactivator
2731:prokaryotic
2443:: 807–822.
2314:27 December
1864:(1): 1–21.
1620:tetrazolium
1551:cell growth
1547:translation
1243:B. subtilis
1168:Allolactose
1077:allolactose
988:: Lactose,
795:called the
771:called the
712:allolactose
490:that pumps
290:: Lactose,
177:transcripts
109:prokaryotic
87:. Although
3679:Categories
3574:Lac operon
3399:Robustness
3378:Modularity
3373:Metamerism
3279:Plasticity
3274:Pleiotropy
3227:Heterotopy
3119:Rho factor
3109:Terminator
3100:eukaryotic
3075:eukaryotic
3056:Elongation
3042:Eukaryotic
3030:Initiation
2813:nucleosome
2796:eukaryotic
2768:gal operon
2763:ara operon
2758:Gua Operon
2753:gab operon
2748:trp operon
2743:lac operon
2714:Eukaryotic
2625:Lac+Operon
2401:J Mol Biol
2223:25 October
1813:Busby S.,
1709:StatPearls
1663:References
1604:two hybrid
753:, and the
682:(RNAP), a
654:Regulation
638:operator,
634:, and the
630:promoter,
619:structural
425:terminator
71:metabolism
3525:Morphogen
3510:Engrailed
3493:Pax genes
3414:Tinkering
3260:Epistasis
3255:Dominance
3166:phenotype
3095:bacterial
3063:bacterial
3037:Bacterial
3011:Insulator
2955:Promotion
2925:Activator
2775:Repressor
2710:Bacterial
2504:0146-0749
2457:0066-4154
1856:operon".
1501:(CAP) or
1346:recessive
1127:lacI gene
820:hydrolyse
664:substrate
488:symporter
474:galactose
431:, and an
429:regulator
398:Structure
341:repressor
322:operon.
221:galactose
142:in 1965.
116:molecular
3488:Hox gene
3476:Elements
3457:Homeobox
3016:Silencer
2994:Enhancer
2982:CAAT box
2972:TATA box
2962:Promoter
2573:18215292
2422:13718526
2392:Jacob F.
2291:10852947
2199:22079752
2156:22257399
1952:18628769
1839:10550204
1767:ndsu.edu
1742:ndsu.edu
1717:33232031
1651:See also
1456:presence
1350:dominant
1215:cellular
1201:used by
1152:in vitro
1000:: lacA.
996:: lacY,
992:: lacZ,
846:operon.
692:upstream
688:promoter
606:gene is
504:encodes
482:encodes
453:encodes
433:operator
421:promoter
419:, and a
247:encodes
227:encodes
3695:Operons
3667:Biology
3619:Debates
3430:Systems
3356:Eyespot
3220:Neoteny
2942:Inducer
2809:histone
2607:29 June
2564:2270259
2522:1315922
2465:9242925
2396:Monod J
2259:Bibcode
2148:9608745
2101:4612528
2013:2182324
1960:8782171
1917:6098691
1815:Ebright
1798:20 June
1722:20 June
1579:E. coli
1505:(CRP).
1464:E. coli
1288:genes (
1248:diauxie
1238:E. coli
1232:During
1227:E. coli
1223:glucose
1219:E. coli
1211:E. coli
1181:E. coli
1117:E. coli
1109:lac p/o
1105:E. coli
1100:in vivo
759:GenBank
737:E. coli
698:-bound
559:E. coli
470:glucose
466:lactose
392:diauxie
217:glucose
215:, into
151:introns
147:E. coli
103:of the
89:glucose
80:E. coli
75:lactose
55:lactose
3653:Portal
3520:Ligand
3200:Operon
2738:Operon
2648:Operon
2631:(MeSH)
2571:
2561:
2520:
2513:372856
2510:
2502:
2463:
2455:
2420:
2374:
2341:
2289:
2279:
2197:
2154:
2146:
2099:
2092:433986
2089:
2042:
2011:
2004:551766
2001:
1958:
1950:
1915:
1878:409848
1876:
1837:
1772:19 May
1747:19 May
1715:
1686:
1487:lacZYA
1427:": -->
1373:marked
1294:lacZYA
1172:isomer
1170:is an
1015:Bottom
1011:laczya
762:(view)
748:lacZYA
746:, the
744:operon
728:lacZYA
672:operon
598:, and
459:enzyme
443:, and
199:, and
67:operon
57:operon
2999:E-box
2851:HDAC1
2653:The '
2601:(PDF)
2594:(PDF)
2547:: 7.
2282:16554
2152:S2CID
1956:S2CID
1616:X-gal
1188:cell.
1160:X-gal
1067:X-gal
925:and O
755:lacI
648:lac o
644:lac o
640:lac o
632:lac p
518:Only
468:into
345:lacI,
185:sugar
165:into
149:lack
3160:The
3070:rpoB
2913:both
2900:CHD7
2831:EZH2
2609:2016
2569:PMID
2518:PMID
2500:ISSN
2461:PMID
2453:ISSN
2418:PMID
2372:ISBN
2368:3–24
2339:ISBN
2331:The
2316:2015
2287:PMID
2225:2007
2195:PMID
2144:PMID
2120:and
2097:PMID
2069:PNAS
2040:ISBN
2009:PMID
1948:PMID
1913:PMID
1874:PMID
1835:PMID
1800:2024
1774:2017
1749:2017
1724:2024
1713:PMID
1684:ISBN
1645:ONPG
1641:lacZ
1633:lacY
1631:and
1629:lacZ
1594:The
1574:good
1539:mRNA
1477:The
1460:cAMP
1446:and
1429:edit
1417:lacI
1401:site
1385:lacY
1381:lacZ
1362:lacI
1358:lacI
1342:lacI
1338:lacI
1330:lacI
1322:lacA
1290:lacI
1275:this
1240:and
1205:and
1185:lacZ
1143:ONPG
1057:ONPG
1047:IPTG
944:or O
917:or O
911:lacZ
899:lacI
877:The
871:LacI
867:LacI
863:LacI
801:lacZ
793:lacZ
781:lacI
751:mRNA
716:lacI
704:lacI
696:cAMP
624:lacZ
608:lacI
600:lacA
596:lacY
592:lacZ
547:lacA
543:lacY
539:lacZ
535:lacI
524:lacY
522:and
520:lacZ
502:lacA
480:lacY
472:and
451:lacZ
445:lacA
441:lacY
437:lacZ
423:, a
411:The
388:EIIA
312:lacA
304:lacY
296:lacZ
265:The
245:lacA
231:, a
225:lacY
219:and
205:lacZ
201:lacA
197:lacY
193:lacZ
181:mRNA
167:mRNA
126:and
118:and
52:The
47:Laci
43:lacI
36:Lacy
32:lacY
18:LacA
3164:of
2977:BRE
2668:Lac
2655:lac
2646:Lac
2635:lac
2589:lac
2559:PMC
2549:doi
2508:PMC
2492:doi
2445:doi
2410:doi
2333:lac
2277:PMC
2267:doi
2187:doi
2183:157
2175:lac
2136:doi
2087:PMC
2077:doi
2063:lac
1999:PMC
1991:doi
1977:lac
1940:doi
1905:doi
1901:180
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