Chi hotspot activity in Escherichia coli without RecBCD exonuclease activity: implications for the mechanism of recombination.

ABSTRACT: The major pathway of genetic recombination and DNA break repair in Escherichia coli requires RecBCD enzyme, a complex nuclease and DNA helicase regulated by Chi sites (5'-GCTGGTGG-3'). During its unwinding of DNA containing Chi, purified RecBCD enzyme has two alternative nucleolytic reactions, depending on the reaction conditions: simple nicking of the Chi-containing strand at Chi or switching of nucleolytic degradation from the Chi-containing strand to its complement at Chi. We describe a set of recC mutants with a novel intracellular phenotype: retention of Chi hotspot activity in genetic crosses but loss of detectable nucleolytic degradation as judged by the growth of mutant T4 and lambda phages and by assay of cell-free extracts. We conclude that RecBCD enzyme's nucleolytic degradation

SUBMITTER: Amundsen SK 

PROVIDER: S-EPMC1774988 | biostudies-literature | 2007 Jan

REPOSITORIES: biostudies-literature