PMID:12702673
| Citation |
Miranda, A and Kuzminov, A (2003) Chromosomal lesion suppression and removal in Escherichia coli via linear DNA degradation. Genetics 163:1255-71 |
|---|---|
| Abstract |
RecBCD is a DNA helicase/exonuclease implicated in degradation of foreign linear DNA and in RecA-dependent recombinational repair of chromosomal lesions in E. coli. The low viability of recA recBC mutants vs. recA mutants indicates the existence of RecA-independent roles for RecBCD. To distinguish among possible RecA-independent roles of the RecBCD enzyme in replication, repair, and DNA degradation, we introduced wild-type and mutant combinations of the recBCD chromosomal region on a low-copy-number plasmid into a DeltarecA DeltarecBCD mutant and determined the viability of resulting strains. Our results argue against ideas that RecBCD is a structural element in the replication factory or is involved in RecA-independent repair of chromosomal lesions. We found that RecBCD-catalyzed DNA degradation is the only activity important for the recA-independent viability, suggesting that degradation of linear tails of sigma-replicating chromosomes could be one of the RecBCD's roles. However, since the weaker DNA degradation capacity due a combination of the RecBC helicase and ssDNA-specific exonucleases restores viability of the DeltarecA DeltarecBCD mutant to a significant extent, we favor suppression of chromosomal lesions via linear DNA degradation at reversed replication forks as the major RecA-independent role of the RecBCD enzyme. |
| Links | |
| Keywords |
DNA/metabolism; DNA Repair; Escherichia coli/genetics; Exodeoxyribonuclease V/genetics; Exodeoxyribonuclease V/metabolism; Rec A Recombinases/genetics; Rec A Recombinases/metabolism |
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