Helicase - Knowledge (XXG)

1165:, juvenile cataracts, and a predisposition to cancers such as osteosarcomas. Chromosomal rearrangements causing genomic instability are found in the cells of Rothmund-Thomson syndrome patients. RecQ is a family of DNA helicase enzymes that are found in various organisms including bacteria, archaea, and eukaryotes (like humans). These enzymes play important roles in DNA metabolism during DNA replication, recombination, and repair. There are five known RecQ helicase proteins in humans: RecQ1, BLM, WRN, RecQ4, and RecQ5. Mutations in some of these genes are associated with genetic disorders. For instance, mutations in the BLM gene cause Bloom syndrome, which is characterized by increased cancer risk and other health issues. Mutations in the WRN gene lead to Werner syndrome, a condition characterized by premature aging and an increased risk of age-related diseases. RecQ helicases are crucial for maintaining genomic stability and integrity. They help prevent the accumulation of genetic abnormalities that can lead to diseases like cancer. Genome integrity depends on the RecQ DNA helicase family, which includes DNA repair, recombination, replication, and transcription processes. Genome instability and early aging are conditions that arise from mutations in human RecQ helicases. RecQ helicase Sgs1 is missing in yeast cells, making them useful models for comprehending human cell abnormalities and the RecQ helicase function. The RecQ helicase family member, RECQ1, is connected to a small number of uncommon genetic cancer disorders in individuals. It participates in transcription, the cell cycle, and DNA repair. According to recent research, missense mutations in the RECQ1 gene may play a role in the development of familial breast cancer. DNA helicases are frequently attracted to regions of DNA damage and are essential for cellular DNA replication, recombination, repair, and transcription. Chemical manipulation of their molecular processes can change the rate at which cancer cells divide, as well as, the efficiency of transactions and cellular homeostasis. Small-molecule-induced entrapment of DNA helicases, a type of DNA metabolic protein, may have deleterious consequences on rapidly proliferating cancer cells, which could be effective in cancer treatment. 1346:, Inc. This assay is a time-resolved fluorescence quenching assay that utilizes the PerkinElmer "SignalClimb" technology that is based on two labels that bind in close proximity to one another but on opposite DNA strands. One label is a fluorescent lanthanide chelate, which serves as the label that is monitored through an adequate 96/384 well plate reader. The other label is an organic quencher molecule. The basis of this assay is the "quenching" or repressing of the lanthanide chelate signal by the organic quencher molecule when the two are in close proximity – as they would be when the DNA duplex is in its native state. Upon helicase activity on the duplex, the quencher and lanthanide labels get separated as the DNA is unwound. This loss in proximity negates the quenchers ability to repress the lanthanide signal, causing a detectable increase in fluorescence that is representative of the amount of unwound DNA and can be used as a quantifiable measurement of helicase activity. The execution and use of single-molecule fluorescence imaging techniques, focusing on methods that include optical trapping in conjunction with epifluorescent imaging, and also surface immobilization in conjunction with total internal reflection fluorescence visualization. Combined with microchannel flow cells and microfluidic control, allow individual fluorescently labeled protein and DNA molecules to be imaged and tracked, affording measurement of DNA unwinding and translocation at single-molecule resolution. 123:

repair processes. Its primary function is to unwind the double-stranded DNA molecule by breaking the hydrogen bonds between the complementary base pairs, allowing the DNA strands to separate. This creates a replication fork, which serves as a template for synthesizing new DNA strands. Helicase is an essential component of cellular mechanisms that ensures accurate DNA replication and maintenance of genetic information. DNA helicase catalyzes regression. RecG and the enzyme PriA work together to rewind duplex DNA, creating a Holliday junction. RecG releases bound proteins and the PriA helicase facilitates DNA reloading to resume DNA replication. RecG replaces the single-strand binding protein (SSB), which regulates the helicase-fork loading sites during fork regression. The SSB protein interacts with DNA helicases PriA and RecG to recover stalled DNA replication forks. These enzymes must bind to the SSB-helicase to be loaded onto stalled forks. Thermal sliding and DNA duplex binding are possibly supported by the wedge domain of RecG's association with the SSB linker. In a regression reaction facilitated by RecG and ATPHollidayjunctions are created for later processing.

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local strand separation occurs by a process wherein the helicase enzyme is loaded at any place along the duplex. This is usually aided by a single-strand region of the RNA, and the loading of the enzyme is accompanied with ATP binding. Once the helicase and ATP are bound, local strand separation occurs, which requires binding of ATP but not the actual process of ATP hydrolysis. Presented with fewer base pairs the duplex then dissociates without further assistance from the enzyme. This mode of unwinding is used by the

228: 1325:. Following detection of the single-strand DNA, the amount of radioactive tag that is on the single-strand DNA is quantified to give a numerical value for the amount of double-strand DNA unwinding.The strand displacement assay is acceptable for qualitative analysis, its inability to display results for more than a single time point, its time consumption, and its dependence on radioactive compounds for labeling warranted the need for development of diagnostics that can monitor helicase activity in real time. 1355:

DNA leading strand, or the DNA lagging strand. To characterize this helicase feature, a partially duplex DNA is used as the substrate that has a central single-strand DNA region with different lengths of duplex regions of DNA (one short region that runs 5'→3' and one longer region that runs 3'→5') on both sides of this region. Once the helicase is added to that central single-strand region, the polarity is determined by characterization on the newly formed single-strand DNA.

1244: 1236: 209:. Studies have shown that helicases may act passively, waiting for uncatalyzed unwinding to take place and then translocating between displaced strands, or can play an active role in catalyzing strand separation using the energy generated in ATP hydrolysis. In the latter case, the helicase acts comparably to an active motor, unwinding and translocating along its substrate as a direct result of its ATPase activity. Helicases may process much faster 988:: This is the largest group of helicases that are involved in varied cellular processes. They are characterized by the presence of nine conserved motifs: Q, I, Ia, Ib, and II through VI. This group is mainly composed of DEAD-box RNA helicases. Some other helicases included in SF2 are the RecQ-like family and the Snf2-like enzymes. Most of the SF2 helicases are type A with a few exceptions such as the XPD family. They have a RecA-like-fold core. 5953: 8124: 1313:. These methods range from assays that are qualitative (assays that usually entail results that do not involve values or measurements) to quantitative (assays with numerical results that can be utilized in statistical and numerical analysis). In 1982–1983, the first direct biochemical assay was developed for measuring helicase activity. This method was called a "strand displacement assay". 1130:(3'-5') belong to the Superfamily II group of helicases, which help to maintain stability of the genome and suppress inappropriate recombination. Deficiencies and/or mutations in RecQ family helicases display aberrant genetic recombination and/or DNA replication, which leads to chromosomal instability and an overall decreased ability to proliferate. Mutations in RecQ family helicases BLM, 1120: 1064:

genital abnormalities, seizures, limited language use and ability, and alpha-thalassemia. The phenotype seen in ATR-X suggests that the mutation of ATRX gene causes the downregulation of gene expression, such as the alpha-globin genes. It is still unknown what causes the expression of the various characteristics of ATR-X in different patients.

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other bacteria, viruses, yeast, flies, and higher eukaryotes. To date, at least 14 different helicases have been isolated from single celled organisms, 6 helicases from bacteriophages, 12 from viruses, 15 from yeast, 8 from plants, 11 from calf thymus, and approximately 25 helicases from human cells. Below is a history of helicase discovery:

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viruses. However, not all RNA helicases exhibit helicase activity as defined by enzymatic function, i.e., proteins of the Swi/Snf family. Although these proteins carry the typical helicase motifs, hydrolize ATP in a nucleic acid-dependent manner, and are built around a helicase core, in general, no unwinding activity is observed.

1223:, FANCM helicase promotes NCO and antagonizes the formation of CO recombinants. Another helicase, RECQ4A/B, also independently reduces COs. It was suggested that COs are restricted because of the long term costs of CO recombination, that is, the breaking up of favourable genetic combinations of alleles built up by past 1284:

RNA helicases and DNA helicases can be found together in all the helicase superfamilies except for SF6. All the eukaryotic RNA helicases that have been identified up to date are non-ring forming and are part of SF1 and SF2. On the other hand, ring-forming RNA helicases have been found in bacteria and

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In xeroderma pigmentosa, the XPD helicase mutation exists at the site of ATP or DNA binding. This results in a structurally functional helicase able to facilitate transcription, however it inhibits its function in unwinding DNA and DNA repair. The lack of a cell's ability to repair mutations, such as

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Various types of mutations found in ATRX have been found to be associated with ATR-X, including most commonly single-base missense mutations, as well as nonsense, frameshift, and deletion mutations. Characteristics of ATR-X include: microcephaly, skeletal and facial abnormalities, mental retardation,

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Helicase polarity, which is also deemed "directionality", is defined as the direction (characterized as 5'→3' or 3'→5') of helicase movement on the DNA/RNA single-strand along which it is moving. This determination of polarity is vital in f.ex. determining whether the tested helicase attaches to the

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RNA helicases that do exhibit unwinding activity have been characterized by at least two different mechanisms: canonical duplex unwinding and local strand separation. Canonical duplex unwinding is the stepwise directional separation of a duplex strand, as described above, for DNA unwinding. However,

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Bloom syndrome is characterized by a predisposition to cancer with early onset, with a mean age-of-onset of 24 years. Cells of Bloom syndrome patients show a high frequency of reciprocal exchange between sister chromatids (SCEs) and excessive chromosomal damage. There is evidence to suggest that BLM

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helicase to cut DNA segments meant for transcription. Although current evidence points to a defect in the XPD helicase resulting in a loss of flexibility in the protein in cases of Cockayne syndrome, it is still unclear how this protein structure leads to the symptoms described in Cockayne syndrome.

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Helicases are classified in 6 groups (superfamilies) based on their shared sequence motifs. Helicases not forming a ring structure are in superfamilies 1 and 2, and ring-forming helicases form part of superfamilies 3 to 6. Helicases are also classified as α or β depending on if they work with single

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in 1976. This helicase was described as a "DNA unwinding enzyme" that is "found to denature DNA duplexes in an ATP-dependent reaction, without detectably degrading". The first eukaryotic DNA helicase discovered was in 1978 in the lily plant. Since then, DNA helicases were discovered and isolated in

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This image represents the different promoter sequences and accessory domains that aid in RNA unwinding (local strand separation). The regions in red are ATP binding domains and the regions in yellow are RNA interaction domains. Specific sequences termed DEAD box proteins are also present that help

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is temperature of the system). Due to this significant activation barrier, its unwinding progression is affected largely by the sequence of nucleic acids within the molecule to unwind, and the presence of destabilization forces acting on the replication fork. Certain nucleic acid combinations will

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involve the separation of nucleic acid strands that necessitates the use of helicases. Some specialized helicases are also involved in sensing of viral nucleic acids during infection and fulfill an immunological function. A helicase is an enzyme that plays a crucial role in the DNA replication and

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Werner syndrome is a disorder of premature aging, with symptoms including early onset of atherosclerosis and osteoporosis and other age related diseases, a high occurrence of sarcoma, and death often occurring from myocardial infarction or cancer in the 4th to 6th decade of life. Cells of Werner

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XPD helicase mutations leading to trichothiodystrophy are found throughout the protein in various locations involved in protein-protein interactions. This mutation results in an unstable protein due to its inability to form stabilizing interactions with other proteins at the points of mutations.

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by unwinding DNA. TFIIH assists in repairing damaged DNA such as sun damage. A mutation in the XPD helicase that helps form this complex and contributes to its function causes the sensitivity to sunlight seen in all three diseases, as well as the increased risk of cancer seen in XP and premature

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gene encodes the ATP-dependent helicase, ATRX (also known as XH2 and XNP) of the SNF2 subgroup family, that is thought to be responsible for functions such as chromatin remodeling, gene regulation, and DNA methylation. These functions assist in prevention of apoptosis, resulting in cortical size

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These two categories of helicases may also be modeled as mechanisms. In such models, the passive helicases are conceptualized as Brownian ratchets, driven by thermal fluctuations and subsequent anisotropic gradients across the DNA lattice. The active helicases, in contrast, are conceptualized as

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It has been suggested that XPD helicase mutations leading to Cockayne syndrome could be the result of mutations within XPD, causing rigidity of the protein and subsequent inability to switch from repair functions to transcription functions due to a "locking" in repair mode. This could cause the

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assay, an assay based on flashplate technology, homogenous time-resolved fluorescence quenching assays, and electrochemiluminescence-based helicase assays". With the use of specialized mathematical equations, some of these assays can be utilized to determine how many base paired nucleotides a

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initiation. They also play an important role in sensing viral RNAs. RNA helicases are involved in the mediation of antiviral immune response because they can identify foreign RNAs in vertebrates. About 80% of all viruses are RNA viruses and they contain their own RNA helicases. Defective RNA

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Other methods were later developed that incorporated some, if not all of the following: high-throughput mechanics, the use of non-radioactive nucleotide labeling, faster reaction time/less time consumption, real-time monitoring of helicase activity (using kinetic measurement instead of

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stepping motors – also known as powerstroke motors – utilizing either a conformational "inch worm" or a hand-over-hand "walking" mechanism to progress. Depending upon the organism, such helix-traversing progress can occur at rotational speeds in the range of 5,000 to 10,000 R.P.M.

994:: Superfamily 3 consists of AAA+ helicases encoded mainly by small DNA viruses and some large nucleocytoplasmic DNA viruses. They have a 3’-5’ translocation directionality, meaning that they are all type A helicases. The most known SF3 helicase is the papilloma virus E1 helicase. 1083:(TTD). Cockayne syndrome and trichothiodystrophy are both developmental disorders involving sensitivity to UV light and premature aging, and Cockayne syndrome exhibits severe mental retardation from the time of birth. The XPD helicase mutation has also been implicated in 1075:(Xeroderma pigmentosum factor D, also known as protein ERCC2) is a 5'-3', Superfamily II, ATP-dependent helicase containing iron-sulphur cluster domains. Inherited point mutations in XPD helicase have been shown to be associated with accelerated aging disorders such as 1048:

regulation, as well as a contribution to the survival of hippocampal and cortical structures, affecting memory and learning. This helicase is located on the X chromosome (Xq13.1-q21.1), in the pericentromeric heterochromatin and binds to

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Factors that contribute to the height of the activation barrier include: specific nucleic acid sequence of the molecule involved, the number of base pairs involved, tension present on the replication fork, and destabilization forces.

970:: This superfamily can be further subdivided into SF1A and SF1B helicases. In this group helicases can have either 3’-5’ (SF1A subfamily) or 5’-3’(SF1B subfamily) translocation polarity. The most known SF1A helicases are Rep and 6759: 341: 677:, where the system lacks a significant barrier, as the helicase can destabilize the nucleic acids, unwinding the double-helix at a constant rate, regardless of the nucleic acid sequence. In active helicases, 3867:

Debnath S., Sharma S. RECQ1 Helicase in Genomic Stability and Cancer. Genes. 2020:11. doi: 10.3390/genes11060622], Debnath S., Sharma S. RECQ1 Helicase in Genomic Stability and Cancer. Genes. 2020:11. doi:

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The size of the activation barrier to overcome by the helicase contributes to its classification as an active or passive helicase. In passive helicases, a significant activation barrier exists (defined as

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An RNA helicase database is currently available online that contains a comprehensive list of RNA helicases with information such as sequence, structure, and biochemical and cellular functions.

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Active helicases show similar behaviour when acting on both double-strand nucleic acids, dsNA, or ssNA, in regards to the rates of unwinding and rates of translocation, where in both systems

6769: 638:) (translocation along the single-strand nucleic acid, ssNA), due to its reliance on the transient unraveling of the base pairs at the replication fork to determine its rate of unwinding. 227: 1154:

syndrome patients exhibit a reduced reproductive lifespan with chromosomal breaks and translocations, as well as large deletions of chromosomal components, causing genomic instability.

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Schaeffer L, Roy R, Humbert S, Moncollin V, Vermeulen W, Hoeijmakers JH, et al. (April 1993). "DNA repair helicase: a component of BTF2 (TFIIH) basic transcription factor".

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Stevenson RE (1993). Adam MP, Everman DB, Mirzaa GM, Pagon RA, Wallace SE, Bean LJ, Gripp KW, Amemiya A (eds.). "Alpha-Thalassemia X-Linked Intellectual Disability Syndrome".

786: 729: 91:. There are many helicases, representing the great variety of processes in which strand separation must be catalyzed. Approximately 1% of eukaryotic genes code for helicases. 6951: 428: 759: 702: 6884: 6862: 534: 457: 938:

The presence of these helicase motifs allows putative helicase activity to be attributed to a given protein, but does not necessarily confirm it as an active helicase.

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helicases have been linked to cancers, infectious diseases and neuro-degenerative disorders. Some neurological disorders associated with defective RNA helicases are:

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protein, with over 90% of them being located in the zinc finger and helicase domains. Mutations of ATRX can result in X-linked-alpha-thalassaemia-mental retardation (

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Linder, P., Lasko, P.F., Ashburner, M., Leroy, P., Nielson, P.J., Nishi, K., Schneir, J., Slonimski, P.P. (1989) Birth of the DEAD-box. Nature (London) 337, 121-122.

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Kitao S, Shimamoto A, Goto M, Miller RW, Smithson WA, Lindor NM, Furuichi Y (May 1999). "Mutations in RECQL4 cause a subset of cases of Rothmund-Thomson syndrome".

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Ouyang KJ, Woo LL, Ellis NA (2008). "Homologous recombination and maintenance of genome integrity: cancer and aging through the prism of human RecQ helicases".

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do, however, support an evolutionary homology among enzymes. Based on these helicase motifs, a number of helicase superfamilies have been distinguished.

963:. They are also classified by translocation polarity. If translocation occurs 3’-5’ the helicase is type A; if translocation occurs 5’-3’ it is type B. 6685: 4767: 4639:

Pavankumar TL, Exell JC, Kowalczykowski SC (1 January 2016). "Direct Fluorescent Imaging of Translocation and Unwinding by Individual DNA Helicases".

1052:. Studies have shown that ATRX plays a role in rDNA methylation and is essential for embryonic development. Mutations have been found throughout the 7644: 6852: 1321:

of DNA duplexes. Following helicase treatment, the single-strand DNA is visually detected as separate from the double-strand DNA by non-denaturing

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Gray MD, Shen JC, Kamath-Loeb AS, Blank A, Sopher BL, Martin GM, et al. (September 1997). "The Werner syndrome protein is a DNA helicase".

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Sung P, Bailly V, Weber C, Thompson LH, Prakash L, Prakash S (October 1993). "Human xeroderma pigmentosum group D gene encodes a DNA helicase".

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Jankowsky E, Fairman-Williams ME (2010). "An introduction to RNA helicases: superfamilies, families, and major themes". In Jankowsky E (ed.).

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Tuteja R, Malhotra P, Song P, Tuteja N, Chauhan VS (2002). "Isolation and characterization of an eIF-4A homologue from Plasmodium cynomolgi".

6491: 4699: 4247: 1016:: They contain the core AAA+ that is not included in the SF3 classification. Some proteins in the SF6 group are: mini chromosome maintenance 1000:: All SF4 family helicases have a type B polarity (5’-3’). They have a RecA fold. The most studied SF4 helicase is gp4 from bacteriophage T7. 7143: 5521: 1330:

endpoint/single point analysis). These methodologies include: "a rapid quench flow method, fluorescence-based assays, filtration assays, a

1211: 1087:(XP), a disorder characterized by sensitivity to UV light and resulting in a several 1000-fold increase in the development of skin cancer. 275: 4029:"Rad51/Dmc1 paralogs and mediators oppose DNA helicases to limit hybrid DNA formation and promote crossovers during meiotic recombination" 5576: 3672:"The Bloom's syndrome helicase (BLM) interacts physically and functionally with p12, the smallest subunit of human DNA polymerase delta" 6937: 6625: 5829: 5760: 5414: 2414:"Two related superfamilies of putative helicases involved in replication, recombination, repair and expression of DNA and RNA genomes" 1879:"Erratum: Opening of nucleic-acid double strands by helicases: Active versus passive opening [Phys. Rev. E 71, 011904 (2005)]" 175: 64: 7843: 6195: 5989: 5423: 4989: 4656: 3305: 2980:"Mutations in a putative global transcriptional regulator cause X-linked mental retardation with alpha-thalassemia (ATR-X syndrome)" 1134:, and WRN, which play a role in regulating homologous recombination, have been shown to result in the autosomal recessive diseases 1103:

This, in turn, destabilizes the entire TFIIH complex, which leads to defects with transcription and repair mechanisms of the cell.

840:– SV40 large tumor antigen reported as a viral helicase (1st reported viral protein that was determined to serve as a DNA helicase) 40:

helicase RuvA (note that the heilcase core in RuvAB complex is RuvB and not RuvA and that RuvA alone do not show helicase activity)

6336: 5844: 5476: 3040:"ATRX encodes a novel member of the SNF2 family of proteins: mutations point to a common mechanism underlying the ATR-X syndrome" 1173: 3334:"Reconstitution of the transcription factor TFIIH: assignment of functions for the three enzymatic subunits, XPB, XPD, and cdk7" 3160:"The helicase XPD unwinds bubble structures and is not stalled by DNA lesions removed by the nucleotide excision repair pathway" 7734: 7729: 5336: 7999: 1139: 7751: 6909: 6904: 6464: 6282: 5146: 4996: 4760: 1331: 1262: 1248:

catalyze reactions in which ATP does not need to be directly hydrolyzed, as long as it binds to the domains on the strand.

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Iyer LM, Leipe DD, Koonin EV, Aravind L (2004). "Evolutionary history and higher order classification of AAA+ ATPases".

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Enzymatic helicase action, such as unwinding nucleic acids is achieved through the lowering of the activation barrier (

7721: 6297: 5137: 4805: 4780: 4582:"RecQ helicase translocates along single-stranded DNA with a moderate processivity and tight mechanochemical coupling" 2580:"Purification and characterization of a DNA helicase from pea chloroplast that translocates in the 3'-to-5' direction" 4081:"Multiple mechanisms limit meiotic crossovers: TOP3α and two BLM homologs antagonize crossovers in parallel to FANCM" 2687:

Singleton MR, Dillingham MS, Wigley DB (2007). "Structure and mechanism of helicases and nucleic acid translocases".

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Lainé JP, Mocquet V, Egly JM (2006). "TFIIH enzymatic activities in transcription and nucleotide excision repair".

1095: 1017: 7984: 569:), while various destabilizing forces can increase the unwinding rate. In passive systems, the rate of unwinding ( 8100: 8087: 8074: 8061: 8048: 8035: 8022: 7780: 7321: 7219: 7044: 7040: 7017: 6990: 6977: 6964: 6895: 6873: 6848: 6823: 6743: 6351: 6311: 6256: 6233: 6205: 6173: 6039: 5320: 1194: 1049: 982:

bacteria. The most known Helicases in the SF1B group are RecD and Dda helicases. They have a RecA-like-fold core.

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Commercially available diagnostic kits are also available. One such kit is the "Trupoint" diagnostic assay from

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codes for 95 non-redundant helicases: 64 RNA helicases and 31 DNA helicases. Many cellular processes, such as

7896: 7705: 7668: 7007: 6218: 4883: 4814: 1266: 7435: 7075: 6672: 6445: 6355: 5855: 5765: 5560: 5380: 5311: 3238:"XPD helicase structures and activities: insights into the cancer and aging phenotypes from XPD mutations" 1413: 1290: 1270: 917: 374: 143: 85: 7917: 7836: 7565: 7473: 6526: 6481: 6183: 6168: 6104: 6084: 5982: 5621: 5306: 5075: 4745: 3873: 1555: 1257: 1189: 1084: 731:, due to the active helicase ability to directly destabilize the replication fork to promote unwinding. 644: 476: 269:) of each specific action. The activation barrier is a result of various factors, and can be defined by 155: 111: 107: 7989: 5967: 4079:

Séguéla-Arnaud M, Crismani W, Larchevêque C, Mazel J, Froger N, Choinard S, et al. (April 2015).

764: 707: 6440: 6435: 6315: 6178: 6158: 6067: 5546: 5353: 5326: 5277: 4593: 4510: 4415: 4092: 3983: 3439: 3385: 2791: 2532: 2226:"Prokaryotic and eukaryotic DNA helicases. Essential molecular motor proteins for cellular machinery" 2182:"Bacteriophage T4 gene 41 protein, required for the synthesis of RNA primers, is also a DNA helicase" 1890: 1736: 1219: 888:– Isolation and characterization of the first biochemically active malarial parasite DNA helicase – 406: 7953: 7770: 6703: 6695: 6476: 6143: 6079: 6043: 5956: 5643: 5507: 5083: 2373:"A new DNA-dependent ATPase which stimulates yeast DNA polymerase I and has DNA-unwinding activity" 1111:

those caused by sun damage, is the cause of the high cancer rate in xeroderma pigmentosa patients.

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Selak N, Bachrati CZ, Shevelev I, Dietschy T, van Loon B, Jacob A, et al. (September 2008).

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complex, a transcription and repair factor in the cell. As part of this complex, it facilitates

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due to the presence of accessory proteins that aid in the destabilization of the fork junction.

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Rqh1 also directs NCO meiotic recombination. These helicases, through their ability to unwind

602: 170:, and RNA degradation are all facilitated by helicases. Helicases move incrementally along one 8144: 7025: 6581: 6571: 6561: 6486: 6470: 6429: 6415: 6410: 6148: 6111: 5839: 5289: 5106: 4705: 4695: 4672: 4652: 4621: 4562: 4492: 4443: 4384: 4343: 4294: 4243: 4220: 4176: 4120: 4058: 4009: 3952: 3944: 3849: 3831: 3782: 3739: 3701: 3649: 3600: 3565: 3507: 3455: 3401: 3355: 3311: 3301: 3267: 3189: 3140: 3117: 3061: 3001: 2947: 2903: 2868: 2819: 2760: 2704: 2636: 2601: 2560: 2501: 2443: 2394: 2353: 2304: 2255: 2203: 2157: 2119: 2022: 1958: 1826: 1764: 1705: 1661: 1607: 1274: 1235: 1224: 1185: 1076: 913: 905: 2700: 901:

The common function of helicases accounts for the fact that they display a certain degree of

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