@article{1d739015bd9a4d3bb5afdaa138309d7c,
title = "The Rad51 paralog complex Rad55-Rad57 acts as a molecular chaperone during homologous recombination",
abstract = "Homologous recombination (HR) is essential for maintenance of genome integrity. Rad51 paralogs fulfill a conserved but undefined role in HR, and their mutations are associated with increased cancer risk in humans. Here, we use single-molecule imaging to reveal that the Saccharomyces cerevisiae Rad51 paralog complex Rad55-Rad57 promotes assembly of Rad51 recombinase filament through transient interactions, providing evidence that it acts like a classical molecular chaperone. Srs2 is an ATP-dependent anti-recombinase that downregulates HR by actively dismantling Rad51 filaments. Contrary to the current model, we find that Rad55-Rad57 does not physically block the movement of Srs2. Instead, Rad55-Rad57 promotes rapid re-assembly of Rad51 filaments after their disruption by Srs2. Our findings support a model in which Rad51 is in flux between free and single-stranded DNA (ssDNA)-bound states, the rate of which is controlled dynamically though the opposing actions of Rad55-Rad57 and Srs2. Roy et al. present a single-molecule analysis of the Rad51 paralog complex Rad55-Rad57. They show that Rad55-Rad57 binds transiently to Rad51-ssDNA to promote Rad51 filament assembly but then dissociates quickly as the filaments mature. They further demonstrate that Rad55-Rad57 does not block the translocase Srs2.",
keywords = "DNA curtains, DNA repair, Rad51, Rad51 paralogs, Rad55-Rad57, Srs2, homologous recombination, single-molecule",
author = "Upasana Roy and Youngho Kwon and Lea Marie and Lorraine Symington and Patrick Sung and Michael Lisby and Greene, {Eric C.}",
note = "Funding Information: We thank Rodney Rothstein and members of the Greene and Sung laboratories for discussions and comments on the manuscript. We thank Simon Boulton, David Rueda, Ondrej Belan, and colleagues for sharing data prior to publication and for comments on our manuscript. This research was funded by NIH grants R35GM118026, R01CA221858, R01CA236606 (to E.C.G.), R35GM126997 (to L.S.), R35CA241801, RO1ES007061 (to P.S.), and PO1CA092584 (to P.S. and E.C.G.); a Gray Foundation Team Science Grant under the Basser Initiative (to P.S.), and a Wellcome Trust Collaborative Award in Science (grant 206292/D/17/Z to E.C.G.). M.L. was supported by the Danish Council for Independent Research, the Villum Foundation, and the Danish National Research Foundation (DNRF115). P.S. is the recipient of a CPRIT REI award (RR180029) and holder of the Robert A. Welch Distinguished Chair in Biochemistry (AQ-0012). U.R. cloned and purified GFP-tagged Rad55-Rad57, designed and conducted all single-molecule assays, and conducted bulk biochemical assays. Y.K. assisted with Rad55-Rad57 expression and purification. L.M. conducted genetic complementation experiments. M.L. conducted all in vivo measurements of Rad55-Rad57 foci. U.R. and E.C.G. co-wrote the manuscript with input from all other co-authors. The authors declare no competing interests. Publisher Copyright: {\textcopyright} 2020 Elsevier Inc.",
year = "2021",
month = mar,
day = "4",
doi = "10.1016/j.molcel.2020.12.019",
language = "English (US)",
volume = "81",
pages = "1043--1057.e8",
journal = "Molecular Cell",
issn = "1097-2765",
publisher = "Cell Press",
number = "5",
}