title: A dual role for mycobacterial RecO in RecA-dependent homologous recombination and RecA-independent single-strand annealing.
abstract: Mycobacteria have two genetically distinct pathways for the homology-directed repair of DNA double-strand breaks: homologous recombination (HR) and single-strand annealing (SSA). HR is abolished by deletion of RecA and reduced in the absence of the AdnAB helicase/nuclease. By contrast, SSA is RecA-independent and requires RecBCD. Here we examine the function of RecO in mycobacterial DNA recombination and repair. Loss of RecO elicits hypersensitivity to DNA damaging agents similar to that caused by deletion of RecA. We show that RecO participates in RecA-dependent HR in a pathway parallel to the AdnAB pathway. We also find that RecO plays a role in the RecA-independent SSA pathway. The mycobacterial RecO protein displays a zinc-dependent DNA binding activity in vitro and accelerates the annealing of SSB-coated single-stranded DNA. These findings establish a role for RecO in two pathways of mycobacterial DNA double-strand break repair and suggest an in vivo function for the DNA annealing activity of RecO proteins, thereby underscoring their similarity to eukaryal Rad52.
authors.affiliation: Division of Infectious Diseases, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
authors.forename: Richa
authors.initials: R
authors.lastname: Gupta
authors.forename: Mikhail
authors.initials: M
authors.lastname: Ryzhikov
authors.forename: Olga
authors.initials: O
authors.lastname: Koroleva
authors.forename: Mihaela
authors.initials: M
authors.lastname: Unciuleac
authors.forename: Stewart
authors.initials: S
authors.lastname: Shuman
authors.forename: Sergey
authors.initials: S
authors.lastname: Korolev
authors.forename: Michael S
authors.initials: MS
authors.lastname: Glickman
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004249:DNA Damage; D004265:DNA Helicases / Q000378:metabolism; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D003851:Deoxyribonucleases / Q000378:metabolism; D043211:Exodeoxyribonuclease V / Q000378:metabolism; D017353:Gene Deletion; D050296:Microbial Viability; D020102:Mycobacterium smegmatis / Q000235:genetics* / Q000254:growth & development; D011938:Rec A Recombinases / Q000378:metabolism*; D059767:Recombinational DNA Repair; D015032:Zinc
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011938:Rec A Recombinases; D003851:Deoxyribonucleases; D043211:Exodeoxyribonuclease V; D004265:DNA Helicases; D015032:Zinc