Recombinational bypass of pyrimidine dimers promoted by the recA protein of Escherichia coli.
recA protein, in the presence of single-stranded DNA binding protein and ATP, promotes the complete exchange of strands between circular single-stranded DNA containing pyrimidine dimers and a homologous linear duplex, converting the pyrimidine dimer-containing single-stranded DNA to a circular duplex. Bypass of a pyrimidine dimer during the branch-migration phase of the reaction requires approximately 20 seconds, a rate 1/50th of that in the absence of the dimer. The circular duplex product is specifically incised by the pyrimidine dimer-specific T4 endonuclease V, and the resulting 3' hydroxyl termini can serve as primers for deoxynucleotide polymerization by DNA polymerase I. These findings indicate that recA protein serves a direct role in recombinational repair and demonstrate that the pyrimidine dimers that have been bypassed can be processed by enzymes of the excision-repair pathway.
D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000235:genetics; D011740:Pyrimidine Dimers / Q000235:genetics*; D011938:Rec A Recombinases; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004277:DNA, Single-Stranded; D011740:Pyrimidine Dimers; D000255:Adenosine Triphosphate; D011938:Rec A Recombinases