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{{Short description|Protein complex}}
{{Short description|Protein complex}}
{{More footnotes|date=October 2017}}


'''RuvABC''' is a complex of three [[protein]]s that mediate [[branch migration]] and resolve the [[Holliday junction]] created during [[Homologous recombination#In bacteria|homologous recombination]] in bacteria. As such, RuvABC is critical to bacterial [[DNA repair]].
'''RuvABC''' is a complex of three [[protein]]s that mediate [[branch migration]] and resolve the [[Holliday junction]] created during [[Homologous recombination#In bacteria|homologous recombination]] in bacteria.<ref name="Wyatt2014">{{cite journal |last1=Wyatt |first1=Hayley D. M. |last2=West |first2=Stephen C. |title=Holliday Junction Resolvases |journal=Cold Spring Harbor Perspectives in Biology |date=1 September 2014 |volume=6 |issue=9 |pages=a023192–a023192 |doi=10.1101/cshperspect.a023192}}</ref> As such, RuvABC is critical to bacterial [[DNA repair]].


[[Image:1ixr.jpg|thumb|320px|right|RuvA-RuvB complex heteromer, Thermus thermophilus]]
[[Image:1ixr.jpg|thumb|320px|right|RuvA-RuvB complex heteromer, Thermus thermophilus]]
RuvA and RuvB bind to the four strand DNA structure<ref>{{Cite web|url=https://www.uniprot.org/uniprot/Q9F1Q3|title = RuvA - Holliday junction ATP-dependent DNA helicase RuvA - Thermus thermophilus (Strain ATCC 27634 / DSM 579 / HB8) - ruvA gene & protein}}</ref> formed in the Holliday junction intermediate, and migrate the strands through each other, using a putative spooling mechanism. The RuvAB complex can carry out DNA helicase activity, which helps unwind the duplex DNA. The binding of the RuvC protein to the RuvAB complex is thought to cleave the DNA strands, thereby resolving the Holliday junction.
RuvA and RuvB bind to the four strand DNA structure formed in the Holliday junction intermediate, and migrate the strands through each other, using a putative spooling mechanism.<ref name="Henkin2020" /> The RuvAB complex can carry out DNA [[helicase]] activity, which helps unwind the duplex DNA. The binding of the RuvC protein to the RuvAB complex is thought to cleave the DNA strands, thereby resolving the Holliday junction.


==Protein complex==
==Protein complex==
The RuvABC is a complex of three proteins that resolve the [[Holliday junction]] formed during bacterial [[Homologous recombination#In bacteria|homologous recombination]]. In ''[[Escherichia coli]]'' bacteria, [[DNA replication]] forks stall at least once per cell cycle, so that DNA replication must be restarted if the cell is to survive.<ref name = Bianco2021>{{cite journal |vauthors=Bianco PR, Lu Y |title=Single-molecule insight into stalled replication fork rescue in Escherichia coli |journal=Nucleic Acids Res |volume=49 |issue=8 |pages=4220–4238 |date=May 2021 |pmid=33744948 |pmc=8096234 |doi=10.1093/nar/gkab142 |url=}}</ref> Replication restart is a multi-step process in ''E. coli'' that requires the sequential action of several proteins. When the progress of the replication fork is impeded the proteins [[single-stranded binding protein]] SSB and RecG [[helicase]] along with the RuvABC complex are required for rescue.<ref name = Bianco2021/> The resolution of [[Holliday junction]]s that accumulate following replication on damaged DNA templates in ''E. coli'' requires the RuvABC complex.<ref>{{cite journal |vauthors=Donaldson JR, Courcelle CT, Courcelle J |title=RuvABC is required to resolve holliday junctions that accumulate following replication on damaged templates in Escherichia coli |journal=J Biol Chem |volume=281 |issue=39 |pages=28811–21 |date=September 2006 |pmid=16895921 |doi=10.1074/jbc.M603933200 |doi-access=free |url=}}</ref>
The RuvABC is a complex of three proteins that resolve the Holliday junction formed during bacterial [[Homologous recombination#In bacteria|homologous recombination]]. In ''[[Escherichia coli]]'', [[DNA replication]] forks stall at least once per cell cycle, so that DNA replication must be restarted if the cell is to survive.<ref name = Bianco2021>{{cite journal |last1=Bianco |first1=Piero R |last2=Lu |first2=Yue |title=Single-molecule insight into stalled replication fork rescue in ''Escherichia coli'' |journal=Nucleic Acids Research |date=7 May 2021 |volume=49 |issue=8 |pages=4220–4238 |doi=10.1093/nar/gkab142 |pmid=33744948 |pmc=8096234}}</ref> Replication restart is a multi-step process in ''E. coli'' that requires the sequential action of several proteins. When the progress of the replication fork is impeded, the [[single-stranded binding protein]] and RecG [[helicase]] along with the RuvABC complex are required for rescue.<ref name = Bianco2021/> The resolution of Holliday junctions that accumulate following replication on damaged DNA templates in ''E. coli'' requires the RuvABC complex.<ref>{{cite journal |last1=Donaldson |first1=Janet R. |last2=Courcelle |first2=Charmain T. |last3=Courcelle |first3=Justin |title=RuvABC Is Required to Resolve Holliday Junctions That Accumulate following Replication on Damaged Templates in ''Escherichia coli'' |journal=Journal of Biological Chemistry |date=September 2006 |volume=281 |issue=39 |pages=28811–28821 |doi=10.1074/jbc.M603933200 |pmid=16895921 |doi-access=free}}</ref>
===RuvA===
===RuvA===
'''RuvA''' (Holliday junction branch migration complex subunit RuvA)<ref name="UniProt1">{{cite web |title=RuvA |url=https://www.uniprot.org/uniprotkb?query=RuvA |website=www.uniprot.org}}</ref> is a DNA-binding protein that binds Holliday junctions with high affinity. The structure of the complex has been variously elucidated through [[X-ray crystallography]] and EM data, and suggest that the complex consists of either one or two RuvA tetramers, with charge lined grooves through which the incoming DNA is channelled. The structure also showed the presence of so-called 'acidic pins' in the centre of the tetramer, which serve to separate the DNA duplexes. Its crystal structure has been solved at 1.9A.
'''RuvA''' is a DNA-binding protein that binds Holliday junctions with high affinity. The structure of the complex has been variously elucidated through [[X-ray crystallography]] and EM data.<ref name="Eggleston1997">{{cite journal |last1=Eggleston |first1=Angela K |last2=Mitchell |first2=Alison H |last3=West |first3=Stephen C |date=May 1997 |title=In Vitro Reconstitution of the Late Steps of Genetic Recombination in E. coli |journal=Cell |volume=89 |issue=4 |pages=607–617 |doi=10.1016/S0092-8674(00)80242-1|doi-access=free }}</ref> RuvA forms a tetramer that binds to the Holliday junction and forces it into a planar configuration.<ref name="Henkin2020" /><ref name="Yamada2004" /> In some cases, a second tetramer binds to the opposite face of the DNA, forming a shell around the junction.<ref name="Henkin2020" /><ref name="Yamada2004" /> The RuvA tetramer has acidic pins near its center that facilitate unwinding and contribute to substrate specificity.<ref name="Wyatt2014" /><ref name="Yamada2004" />


===RuvB===
===RuvB===
'''RuvB''' (Holliday junction branch migration complex subunit RuvB)<ref name="UniProt2">{{cite web |title=RuvB |url=https://www.uniprot.org/uniprotkb?query=RuvB |website=www.uniprot.org |access-date=6 April 2024}}</ref> is an ATPase that is only active in the presence of DNA and compared to RuvA, RuvB has a low affinity for DNA. The RuvB proteins are thought to form hexameric rings on the exit points of the newly formed DNA duplexes, and it is proposed that they 'spool' the emerging DNA through the RuvA tetramer.
'''RuvB''' is a DNA-dependent [[ATPase]] that forms a hexameric ring around the arms of the Holliday junction.<ref name="Henkin2020" /><ref name="Eggleston1997" /> RuvB is thought to pump the DNA through RuvA using the energy generated by the hydrolysis of ATP. This converts the homoduplex DNA into heteroduplex.<ref name="Wyatt2014" />


===RuvC===
===RuvC===
'''RuvC''' (Crossover junction endodeoxyribonuclease RuvC)<ref name="UniProt3">{{cite web |title=RuvC |url=https://www.uniprot.org/uniprotkb?query=RuvC |website=www.uniprot.org |access-date=6 April 2024}}</ref> is the resolvase, which cleaves the Holliday junction. RuvC proteins have been shown to form dimers in solution and its structure has been solved at 2.5A. It is thought to bind either on the open, DNA exposed face of a single RuvA tetramer, or to replace one of the two tetramers. Binding is proposed to be mediated by an unstructured loop on RuvC, which becomes structured on binding RuvA. RuvC can be bound to the complex in either orientation, therefore resolving Holliday junctions in either a horizontal or vertical manner.
'''RuvC''' is the resolvase, which cleaves the Holliday junction. RuvC binds to Holliday junctions as a homodimer.<ref name="Wyatt2014" /> As a homodimer, there are two active [[endonuclease]] sites, each of which can form a double-strand break.<ref name="Henkin2020">{{cite book |last1=Henkin |first1=Tina M. |last2=Peters |first2=Joseph E. |title=Molecular Genetics of Bacteria |date=2020 |publisher=American Society for Microbiology |isbn=9781683673576 |pages=371-373 |edition=Fifth |chapter=Molecular Mechanisms of Homologous Recombination}}</ref> RuvC can be bound to the complex in either orientation, therefore resolving Holliday junctions in either a horizontal or vertical manner.<ref name="Eggleston1997" /> There are multiple theories as to how RuvC is able to access the branch migration complex.<ref name="Yamada2004">{{cite journal |last1=Yamada |first1=Kazuhiro |last2=Ariyoshi |first2=Mariko |last3=Morikawa |first3=Kosuke |title=Three-dimensional structural views of branch migration and resolution in DNA homologous recombination |journal=Current Opinion in Structural Biology |date=April 2004 |volume=14 |issue=2 |pages=130–137 |doi=10.1016/j.sbi.2004.03.005}}</ref> One theory is that a RuvA tetramer binds only to one side of the DNA, leaving an exposed face for RuvC to bind to. An alternative theory is that RuvA does not maintain the shell like structure it initially forms around the junction, but rather opens up to allow RuvC to access the DNA.<ref name="Henkin2020" />


==See also==
==See also==
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==Further reading==
==Further reading==
* {{cite journal |author=West SC |title=Molecular views of recombination proteins and their control |journal=Nat. Rev. Mol. Cell Biol. |volume=4 |issue=6 |pages=435–45 |year=2003 |pmid=12778123 |doi=10.1038/nrm1127|s2cid=28474965 }}
* {{cite journal |last1=West |first1=Stephen C. |title=Molecular views of recombination proteins and their control |journal=Nature Reviews Molecular Cell Biology |date=June 2003 |volume=4 |issue=6 |pages=435–445 |doi=10.1038/nrm1127 |pmid=12778123 |s2cid=28474965 }}
* {{cite journal |author=Kowalczykowski SC |title=Initiation of genetic recombination and recombination-dependent replication |journal=Trends Biochem. Sci. |volume=25 |issue=4 |pages=156–65 |year=2000 |pmid=10754547|doi=10.1016/S0968-0004(00)01569-3}}
* {{cite journal |last1=Kowalczykowski |first1=Stephen C |title=Initiation of genetic recombination and recombination-dependent replication |journal=Trends in Biochemical Sciences |date=April 2000 |volume=25 |issue=4 |pages=156–165 |doi=10.1016/S0968-0004(00)01569-3}}
*Eggleston AK, Mitchell AH, and West SC (1997). “In Vitro Reconstitution of the Late Steps of Genetic Recombination in E. coli”. Cell. 89: 607–617.


==External links==
==External links==
* {{MeshName|Holliday+Junction+Resolvases}}
* {{MeshName|Holliday+Junction+Resolvases}}


[[Category:Proteins]]
[[Category:Protein complexes]]
[[Category:Bacterial enzymes]]

Revision as of 11:45, 9 June 2025

Template:Short description

RuvABC is a complex of three proteins that mediate branch migration and resolve the Holliday junction created during homologous recombination in bacteria.[1] As such, RuvABC is critical to bacterial DNA repair.

File:1ixr.jpg
RuvA-RuvB complex heteromer, Thermus thermophilus

RuvA and RuvB bind to the four strand DNA structure formed in the Holliday junction intermediate, and migrate the strands through each other, using a putative spooling mechanism.[2] The RuvAB complex can carry out DNA helicase activity, which helps unwind the duplex DNA. The binding of the RuvC protein to the RuvAB complex is thought to cleave the DNA strands, thereby resolving the Holliday junction.

Protein complex

The RuvABC is a complex of three proteins that resolve the Holliday junction formed during bacterial homologous recombination. In Escherichia coli, DNA replication forks stall at least once per cell cycle, so that DNA replication must be restarted if the cell is to survive.[3] Replication restart is a multi-step process in E. coli that requires the sequential action of several proteins. When the progress of the replication fork is impeded, the single-stranded binding protein and RecG helicase along with the RuvABC complex are required for rescue.[3] The resolution of Holliday junctions that accumulate following replication on damaged DNA templates in E. coli requires the RuvABC complex.[4]

RuvA

RuvA is a DNA-binding protein that binds Holliday junctions with high affinity. The structure of the complex has been variously elucidated through X-ray crystallography and EM data.[5] RuvA forms a tetramer that binds to the Holliday junction and forces it into a planar configuration.[2][6] In some cases, a second tetramer binds to the opposite face of the DNA, forming a shell around the junction.[2][6] The RuvA tetramer has acidic pins near its center that facilitate unwinding and contribute to substrate specificity.[1][6]

RuvB

RuvB is a DNA-dependent ATPase that forms a hexameric ring around the arms of the Holliday junction.[2][5] RuvB is thought to pump the DNA through RuvA using the energy generated by the hydrolysis of ATP. This converts the homoduplex DNA into heteroduplex.[1]

RuvC

RuvC is the resolvase, which cleaves the Holliday junction. RuvC binds to Holliday junctions as a homodimer.[1] As a homodimer, there are two active endonuclease sites, each of which can form a double-strand break.[2] RuvC can be bound to the complex in either orientation, therefore resolving Holliday junctions in either a horizontal or vertical manner.[5] There are multiple theories as to how RuvC is able to access the branch migration complex.[6] One theory is that a RuvA tetramer binds only to one side of the DNA, leaving an exposed face for RuvC to bind to. An alternative theory is that RuvA does not maintain the shell like structure it initially forms around the junction, but rather opens up to allow RuvC to access the DNA.[2]

See also

References

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Further reading

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External links