Bacillus subtilis RecO nucleates RecA onto SsbA-coated single-stranded DNA.
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.
Manfredi
Candela
C
Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, C/Darwin 3, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Carrasco
Begoña
B
Ayora
Silvia
S
Alonso
Juan C
JC
D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000502:physiology; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic / Q000502:physiology
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011938:Rec A Recombinases