Escherichia coli RecBC helicase has two translocase activities controlled by a single ATPase motor.

ABSTRACT: E. coli RecBCD is a DNA helicase with two ATPase motors (RecB, a 3'?5' translocase, and RecD, a 5'?3' translocase) that function in repair of double-stranded DNA breaks. The RecBC heterodimer, with only the RecB motor, remains a processive helicase. Here we examined RecBC translocation along single-stranded DNA (ssDNA). Notably, we found RecBC to have two translocase activities: the primary translocase moves 3'?5', whereas the secondary translocase moves RecBC along the opposite strand of a forked DNA at a similar rate. The secondary translocase is insensitive to the ssDNA backbone polarity, and we propose that it may fuel RecBCD translocation along double-stranded DNA ahead of the unwinding fork and ensure that the unwound single strands move through RecBCD at the same rate after interaction with a crossover hot-spot indicator (Chi) sequence.

SUBMITTER: Wu CG 

PROVIDER: S-EPMC2950890 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature