Identification of the Escherichia coli recB and recC gene products.

Abstract

Functional recB and recC genes are required for normal conjugative genetic recombination in Escherichia coli1–3 and mutations in either of these genes lead to deficiency in an ATP-dependent nuclease known as the RecBC DNase or exonuclease V (refs 4–6). Widely different molecular weights have been reported for the putative subunits of this enzyme7,8 and genetic and biochemical experiments have left some doubt about whether or not recB and recC are different genes. We have now cloned the recB and recC genes separately into the multiple copy number plasmid pAT153 and identified the gene products by transposon inactivation and gel electrophoresis. The products of the recB and recC genes are proteins of molecular weights (MW) 135,000 and 125,000, respectively.