S C West

..Genetic and biochemical studies indicate that branch migration and resolution are coupled by direct interactions between the three proteins, possibly by the formation of a RuvABC complex...

..These results show that the ruvA and ruvB genes encode a DNA helicase that specifically recognizes Holliday junctions and promotes branch migration...

..0). No energy cofactors are needed. When RuvC was analyzed by gel filtration and polyacrylamide gel electrophoresis, monomeric and dimeric forms of the protein were observed...

..We suggest that the extreme sensitivity of paralog-defective cell lines to cross-linking agents is owing to defects in the processing of incised cross links and the consequential failure to initiate recombinational repair at these sites...

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..Thus, BRCA2 regulates both the intracellular localization and DNA binding ability of RAD51. Loss of these controls following BRCA2 inactivation may be a key event leading to genomic instability and tumorigenesis...

..Consistent with the requirement for two recombinases in meiotic recombination, hDmc1 interacts directly with hRad51...

..coli RuvABC, highlighting the preservation of this essential pathway in recombination and DNA repair from prokaryotes to mammals...

..Under certain conditions, the bypass of heterology is stimulated by the single-strand binding protein SSB...

..These results show that the RuvAB proteins, which are induced as part of the SOS response to DNA damage, allow genetic recombination and the recombinational repair of DNA to occur in the presence of extensive lengths of heterology...

..We interpret these differences in terms of the contiguity of the RecA nucleoprotein filament which may, under certain conditions, limit access to the Holliday junction resolvase...

..The newly identified RuvC protein resolves the intermediates by specific endonucleolytic cleavage to produce recombinant DNA molecules...

..The UV sensitivity and deficiency in recombinational repair of DNA exhibited by ruv mutants lead us to suggest that RuvC resolves Holliday junctions in vivo...

..We suggest that the RuvA and RuvB proteins play a specific role in the branch migration of Holliday junctions during postreplication repair of DNA damage in E. coli...

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..It is proposed that hRad51 mediates homology recognition and initiates strand exchange, but that extensive heteroduplex formation in higher organisms requires the actions of additional proteins...

..Here we show that hRad52 stimulates homologous pairing by hRad51. The DNA-binding properties of hRad52 indicate that Rad52 is involved in an early stage of Rad51-mediated recombination...

..Finally, we have used electron microscopy to visualise RadA-mediated joint molecules, the intermediates of homologous recombination. Intriguingly, RadA shares properties of both the bacterial RecA and eukaryotic Rad51 recombinases...

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..This protein-DNA arrangement may facilitate the DNA-DNA interactions necessary for RAD52-mediated annealing of complementary DNA strands...

..These results show that topological constraints affecting Holliday junction structure influence the orientation of resolution by cellular resolvases...

..Purified RAD51C--XRCC3 complex binds single-stranded, but not duplex DNA, to form protein--DNA networks that have been visualized by electron microscopy...

..These observations may indicate that other proteins are required for efficient RuvC-mediated resolution...

..These data show that XPG has a direct role in making one of the incisions required to excise a damaged oligonucleotide, by cleaving 3' to DNA damage during nucleotide excision repair...

..We show that heteroduplex DNA may be formed in vitro by ATP-dependent strand exchange catalysed by RecA protein or by the RuvA and RuvB proteins of E. coli...

..The newly discovered biochemical properties of RuvA, RuvB, and RuvC are incorporated into a model for the postreplicational repair of DNA following UV irradiation...

..In these studies, junction targeting was achieved by incorporating uncharged methyl phosphonates into the DNA backbone, providing further evidence for the importance of charge-charge repulsions in determining DNA structure...

..This review summarizes the key roles played by the two recombinases, Dmc1 and Rad51, in the faithful repair of DNA breaks...

..Addition of purified RuvA and RuvB to a RecA-mediated recombination reaction was found to stimulate the rate of strand exchange leading to the rapid formation of heteroduplex DNA...

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..Complex formation was not facilitated by duplex DNA. The identification of a RuvABC-junction complex provides direct evidence that the RuvABC proteins interact at the Holliday junction...

..The third protein, RuvC, which acts independently of RuvA and RuvB, resolves recombination intermediates by specific endonucleolytic cleavage of the Holliday junction...

..We propose that efficient RuvC resolution requires the translocation of Holliday junctions to specific cleavage sites, thus providing a biochemical basis for the similar genetic defects observed in ruvA, ruvB, and ruvC mutants...

..The involvement of inositol phosphate in DNA-PK-dependent NHEJ is of particular interest since the catalytic domain of DNA-PKcs is similar to that found in the phosphatidylinositol 3 (PI 3)-kinase family...

..Joint molecule formation by hRad51 was stimulated or inhibited by hRad52, dependent upon the reaction conditions. The inhibitory effect could be overcome by the presence of hRP-A or excess heterologous DNA...

..In contrast to yeast Rad51 protein, human Rad51 forms filaments with single-stranded DNA in the presence of ATP/ATP gamma S. These resemble the inactive form of the RecA filament which is observed in the absence of a nucleotide cofactor...

..The interactions of BRCA2 with RAD51 and DMC1 lead us to suggest that the BRCA2 tumour suppressor is a universal regulator of recombinase actions...

..The role that Rad1-Rad10 plays in recombination is likely to resemble its activity in NER by acting upon partially unpaired DNA intermediates such as those formed by recombination mechanisms involving single-strand DNA annealing...

..This finding holds promise that the development of in vitro systems for recombination by eukaryotic proteins lies in the not-too-distant future...

..The N-terminal domain of Rad51 and the C-terminal domain of RecA may have arisen from convergent evolution to play similar roles in the filaments...

..We present a model in which BLM disrupts potentially recombinogenic molecules that arise at sites of stalled replication forks. Our results have implications for the role of BLM as an anti-recombinase in the suppression of tumorigenesis...

..These interactions are spatially and temporally associated with synapsis during meiotic prophase I...

..These results provide strong evidence that additional activities are crucial for NHEJ and V(D)J recombination in mammals...

..Thus, the structures formed by the hexameric helicases may be a more general property of other proteins involved in DNA metabolism, including those, such as Rad52, that do not bind and hydrolyze ATP...