J. Biol. Chem., Vol. 256, Issue 20, 10415-10419, Oct, 1981
Effect of recA protein on the DNAse activities of the recBC enzyme
A Prell and W Wackernagel
In Escherichia coli, the recBC enzyme is required for several cellular
functions including recombination proficiency, UV resistance, and DNA
breakdown following radiation damage to the chromosome, all of which appear
to be also under the control of the recA gene. We have studied the
influence of purified recA protein on the various nucleolytic activities of
the recBC enzyme. Conditions were chosen (with GTP as nucleoside
triphosphate) under which recA protein binds to single- stranded DNA
without catalyzing D-loop formation and which are favorable for the DNase
activities of the recBC enzyme. We found that the degradation of linear
duplex DNA was unaffected, but that the endonuclease and exonuclease
activities for single-stranded DNA were inhibited by about 50% and 35%,
respectively. In contrast, no protection of circular duplex DNA containing
single-stranded regions was observed. The results suggest that the recA
protein by itself may not act as a potent inhibitor of recBC
enzyme-dependent DNA degradation in vivo.