title: Human Rad52-mediated homology search and annealing occurs by continuous interactions between overlapping nucleoprotein complexes.
abstract: The Rad52 protein has critical functions in distinct pathways of the homology-directed DNA repair, one of which is to promote the annealing of complementary strands of DNA. Both yeast and human Rad52 proteins organize into ring-shaped oligomers with the predominant form being a heptamer. Despite the wealth of information obtained in previous investigations, how Rad52 mediates homology search and annealing remains unclear. Here, we developed single-molecule fluorescence resonance energy transfer approaches to probe hRad52-mediated DNA annealing events in real time. We found that annealing proceeds in successive steps involving rearrangements of the ssDNA-hRad52 complex. Moreover, after initial pairing, further search for extended homology occurs without dissociation. This search process is driven by an interaction between 2 overlapping nucleoprotein complexes. In light of these observations we propose a model for hRad52-mediated DNA annealing where ssDNA release and dsDNA zippering are coordinated through successive rearrangement of overlapping nucleoprotein complexes.
authors.affiliation: Howard Hughes Medical Institute and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Eli
authors.initials: E
authors.lastname: Rothenberg
authors.forename: Jill M
authors.initials: JM
authors.lastname: Grimme
authors.forename: Maria
authors.initials: M
authors.lastname: Spies
authors.forename: Taekjip
authors.initials: T
authors.lastname: Ha
mesh_terms: D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D008956:Models, Chemical; D046912:Multiprotein Complexes; D009698:Nucleoproteins / Q000378:metabolism*; D051721:Rad52 DNA Repair and Recombination Protein / Q000378:metabolism*; D011995:Recombination, Genetic
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D009698:Nucleoproteins; C497194:RAD52 protein, human; D051721:Rad52 DNA Repair and Recombination Protein