title: RecO protein initiates DNA recombination and strand annealing through two alternative DNA binding mechanisms.
abstract: Recombination mediator proteins (RMPs) are important for genome stability in all organisms. Several RMPs support two alternative reactions: initiation of homologous recombination and DNA annealing. We examined mechanisms of RMPs in both reactions with Mycobacterium smegmatis RecO (MsRecO) and demonstrated that MsRecO interacts with ssDNA by two distinct mechanisms. Zinc stimulates MsRecO binding to ssDNA during annealing, whereas the recombination function is zinc-independent and is regulated by interaction with MsRecR. Thus, different structural motifs or conformations of MsRecO are responsible for interaction with ssDNA during annealing and recombination. Neither annealing nor recombinase loading depends on MsRecO interaction with the conserved C-terminal tail of single-stranded (ss) DNA-binding protein (SSB), which is known to bind Escherichia coli RecO. However, similarly to E. coli proteins, MsRecO and MsRecOR do not dismiss SSB from ssDNA, suggesting that RMPs form a complex with SSB-ssDNA even in the absence of binding to the major protein interaction motif. We propose that alternative conformations of such complexes define the mechanism by which RMPs initiate the repair of stalled replication and support two different functions during recombinational repair of DNA breaks.
authors.affiliation: From the Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104 and.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Ryzhikov
authors.affiliation: Division of Infectious Diseases and Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Richa
authors.initials: R
authors.lastname: Gupta
authors.affiliation: Division of Infectious Diseases and Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Michael
authors.initials: M
authors.lastname: Glickman
authors.affiliation: From the Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104 and korolevs@slu.edu.
authors.forename: Sergey
authors.initials: S
authors.lastname: Korolev
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D020816:Amino Acid Motifs; D004247:DNA / Q000737:chemistry*; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D020102:Mycobacterium smegmatis / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011995:Recombination, Genetic; D015032:Zinc / Q000737:chemistry
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C081006:RecO protein, E coli; C489318:RecR protein, E coli; D000255:Adenosine Triphosphate; D004247:DNA; D015032:Zinc
keywords: DNA Repair; DNA-binding Protein; Homologous Recombination; Protein Structure; Protein-Protein Interaction