Resolution of Holliday junctions by RuvABC prevents dimer formation in <i>rep</i> mutants and UV‐irradiated cells

Michel, Bertrand; Recchia, Gavin D.; Penel‐Colin, Marion; Ehrlich, S. Dusko; Sherratt, David J.

doi:10.1046/j.1365-2958.2000.01989.x

Cited by 72 publications

(52 citation statements)

References 26 publications

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“…6D). This is consistent with recent results of Michel et al, who demonstrated that RecA protein, but not RecO or RecF, is required for certain in vivo reactions that lead up to formation of an intermediate that can be processed by the RuvABC system (46). Although many questions remain about the protein transactions that might take place in replication fork repair, it is now clear that RecA protein can promote the potentially critical fork regression process in at least some situations.…”

Section: Discussionsupporting

confidence: 90%

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RecA protein promotes the regression of stalled replication forks in vitro

Robu

Inman²,

Cox³

2001

Proc. Natl. Acad. Sci. U.S.A.

149

120

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Replication forks are halted by many types of DNA damage. At the site of a leading-strand DNA lesion, forks may stall and leave the lesion in a single-strand gap. Fork regression is the first step in several proposed pathways that permit repair without generating a double-strand break. Using model DNA substrates designed to mimic one of the known structures of a fork stalled at a leadingstrand lesion, we show here that RecA protein of Escherichia coli will promote a fork regression reaction in vitro. The regression process exhibits an absolute requirement for ATP hydrolysis and is enhanced when dATP replaces ATP. The reaction is not affected by the inclusion of the RecO and R proteins. We present this reaction as one of several potential RecA protein roles in the repair of stalled and͞or collapsed replication forks in bacteria.

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Section: Discussionsupporting

confidence: 90%

“…In the cell, this intermediate could then be processed by other enzymes such as the RuvABC system (15,21,46). ATP hydrolysis is clearly required for the four-strand DNA strand-exchange reactions promoted by RecA protein in vitro (24,38).…”

Section: Discussionmentioning

confidence: 99%

RecA protein promotes the regression of stalled replication forks in vitro

Robu

Inman²,

Cox³

2001

Proc. Natl. Acad. Sci. U.S.A.

149

120

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“…Molecular mechanisms that can introduce such bias in HJ processing by the Ruv resolvasome have been uncovered in E. coli (23,24). The ability of the Ruv proteins to bias HJ resolution toward noncrossovers is confirmed by the observation that increasing the frequency of replication fork stalling͞breaking makes E. coli cells become dependent on Xer recombination for survival when the ruv genes are mutated (25).…”

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confidence: 98%

“…1; refs. [23][24][25], the pathways of recombination intermediate resolution in the absence of Ruv, and their lack of apparent bias, remain unclear. Nevertheless, the importance of recombination proteins, with or without the recombination process in replication fork restart is now well established.…”

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confidence: 99%

Circles: The replication-recombination-chromosome segregation connection

Barre

Søballe²,

Michel³

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

109

114

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Crossing over by homologous recombination between monomeric circular chromosomes generates dimeric circular chromosomes that cannot be segregated to daughter cells during cell division. In Escherichia coli, homologous recombination is biased so that most homologous recombination events generate noncrossover monomeric circular chromosomes. This bias is lost in ruv mutants. A novel protein, RarA, which is highly conserved in eubacteria and eukaryotes and is related to the RuvB and the DnaX proteins, ␥ and , may influence the formation of crossover recombinants. Those dimeric chromosomes that do form are converted to monomers by Xer site-specific recombination at the recombination site dif, located in the replication terminus region of the E. coli chromosome. The septum-located FtsK protein, which coordinates cell division with chromosome segregation, is required for a complete Xer recombination reaction at dif. Only correctly positioned dif sites present in a chromosomal dimer are able to access septum-located FtsK. FtsK acts by facilitating a conformational change in the Xer recombination Holliday junction intermediate formed by XerC recombinase. This change provides a substrate for XerD, which then completes the recombination reaction.homologous recombination ͉ Ruv͞Xer recombination ͉ dimer resolution ͉ FtsK B arbara McClintock, during her work on ring chromosomes in maize, inferred in 1932 that whereas crossing over between rod-shaped (linear) chromosomes does not alter their topology, crossing over between ring (circular) chromosomes generates larger ring chromosomes (circular dimers) that cannot be segregated normally at cell division (1). This topological complication arising from crossing over between circular chromosomes was largely ignored until the 1980s, when it was demonstrated that site-specific recombination systems act to convert dimeric plasmid molecules, formed by homologous recombination, to monomers, and thereby facilitate stable plasmid inheritance (2, 3). Subsequently, it was shown that one of these site-specific recombination systems, XerCD site-specific recombination, also functions in the conversion of dimeric Escherichia coli chromosomes to monomers (4-6). Xer recombination uses two related recombinases, XerC and XerD, belonging to the tyrosine recombinase family, each recombinase catalyzing the exchange of one pair of strands in a reaction that proceeds through a Holliday junction (HJ) intermediate (7)(8)(9). XerCD act at the recombination site dif, located in the replication terminus region of the E. coli chromosome and at related sites in multicopy plasmids, for example, psi in plasmid pSC101 and cer in ColE1 (3, 10).Here we outline the processes that limit dimer formation by homologous crossing over in E. coli. We also discuss the mechanism that restricts Xer recombination at chromosomal dif to converting dimers to monomers by making a part of the recombination machine only accessible to dif sites when they are present in chromosomal dimers at the time of cell division.Homologous recom...

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“…This is accomplished by bacterial Xer-like site-specific recombination systems that catalyze the resolution of the dimers (55). It has been shown in vitro that the orientation of the RuvABC Eco complex determines the direction of cleavage (60), and it is proposed that the repair of broken replication forks is biased to the generation of noncrossover products (14,41). However, in E. coli, chromosome dimers are formed by homologous recombination (HR) between sister chromosomes in about 14% of cells growing under standard laboratory conditions (46,58).…”

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confidence: 99%

Genetic Recombination inBacillus subtilis168: Contribution of Holliday Junction Processing Functions in Chromosome Segregation

et al. 2004

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Bacillus subtilis mutants classified within the (ruvA, ⌬ruvB, ⌬recU, and recD) and (⌬recG) epistatic groups, in an otherwise rec ؉ background, render cells impaired in chromosomal segregation. A less-pronounced segregation defect in ⌬recA and ⌬sms (⌬radA) cells was observed. The repair deficiency of addAB, ⌬recO, ⌬recR, recH, ⌬recS, and ⌬subA cells did not correlate with a chromosomal segregation defect. The sensitivity of epistatic group mutants to DNA-damaging agents correlates with ongoing DNA replication at the time of exposure to the agents. The ⌬sms (⌬radA) and ⌬subA mutations partially suppress the DNA repair defect in ruvA and recD cells and the segregation defect in ruvA and ⌬recG cells. The ⌬sms (⌬radA) and ⌬subA mutations partially suppress the DNA repair defect of ⌬recU cells but do not suppress the segregation defect in these cells. The ⌬recA mutation suppresses the segregation defect but does not suppress the DNA repair defect in ⌬recU cells. These results result suggest that (i) the RuvAB and RecG branch migrating DNA helicases, the RecU Holliday junction (HJ) resolvase, and RecD bias HJ resolution towards noncrossovers and that (ii) Sms (RadA) and SubA proteins might play a role in the stabilization and or processing of HJ intermediates.Cells have evolved several mechanisms to maintain the structural and informational fidelity of their DNA and to participate in sister chromatid segregation. UV and certain chemical compounds (e.g., 4-nitroquinoline-1-oxide [4NQO] and methyl methanesulfonate [MMS]), generate deleterious obstacles to DNA replication. Stalling of the replication fork due to such obstacles or the collapse of the replication machinery with resulting unrepaired single-strand nicks or double-strand breaks (DSBs) blocks replication fork progression in all organisms (13,21,54). The block must be repaired or removed, and replication must be restarted. Current models for DSB repair involve the formation of Holliday junctions (HJs) that need to be resolved to allow the repaired chromosomes to separate. The Escherichia coli RuvAB (RuvAB Eco ) helicase, together with the RuvC Eco HJ-specific endonuclease, target the HJ at the stalled fork and cleave on opposite strands. If the symmetric HJs are resolved at random, crossovers and noncrossover products are generated. In circular chromosomes, the outcome will be a dimeric chromosome or two monomeric chromosomes, respectively. Dimeric chromosomes are lethal and need to be resolved before cell division. This is accomplished by bacterial Xer-like site-specific recombination systems that catalyze the resolution of the dimers (55). It has been shown in vitro that the orientation of the RuvABC Eco complex determines the direction of cleavage (60), and it is proposed that the repair of broken replication forks is biased to the generation of noncrossover products (14, 41). However, in E. coli, chromosome dimers are formed by homologous recombination (HR) between sister chromosomes in about 14% of cells growing under standard laboratory conditions (46,58)....

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Resolution of Holliday junctions by RuvABC prevents dimer formation in rep mutants and UV‐irradiated cells

Cited by 72 publications

References 26 publications

RecA protein promotes the regression of stalled replication forks in vitro

RecA protein promotes the regression of stalled replication forks in vitro

Circles: The replication-recombination-chromosome segregation connection

Genetic Recombination inBacillus subtilis168: Contribution of Holliday Junction Processing Functions in Chromosome Segregation

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