Bacillus subtilis RecO Nucleates RecA onto SsbA-coated Single-stranded DNA

• Published in: The Journal of biological chemistry Vol. 283; no. 36; pp. 24837 - 24847
• Main Authors: Manfredi, Candela, Carrasco, Begoña, Ayora, Silvia, Alonso, Juan C.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 05.09.2008; American Society for Biochemistry and Molecular Biology
• Subjects: Bacillus subtilis - genetics; Bacillus subtilis - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; DNA Breaks, Double-Stranded; DNA Repair - physiology; DNA, Bacterial - genetics; DNA, Bacterial - metabolism; DNA, Single-Stranded - genetics; DNA, Single-Stranded - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; DNA: , Repair, Recombination, and Chromosome Dynamics; Rec A Recombinases - genetics; Rec A Recombinases - metabolism; Recombination, Genetic - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M802002200

Subsaturating amounts of Bacillus subtilis SsbA, independently of the order of addition, partially inhibit the single-stranded DNA-dependent dATPase activity of RecA. This negative effect is fully overcome when a substoichiometric amount of RecO is added. SsbA added prior to RecA does not stimulate the dATP-dependent DNA strand exchange activity; however, added after RecA it enhances the extent of strand exchange. The addition of RecO stimulates RecA-mediated joint molecule formation, although it limits the accumulation of final recombination products. Thus we suggest that RecO has a dual activity: RecO acts as a RecA mediator enabling RecA to utilize SsbA-coated single-stranded DNA as a polymerization substrate and controls RecA-mediated DNA strand exchange by limiting its extent. We herein discuss the possible mechanisms of RecO involvement in the regulation of double strand break repair and genetic transformation.