Fine structure of the [formula omitted] and [formula omitted] gene region of [formula omitted

Abstract

For genetic and enzymatic study of recBC DNase, the Escherichia coli thyA, recC, recB and argA gene region cloned in a cosmid was subcloned into the pBR322 plasmid vector and its fine restriction map was made. Complementation analysis showed that these genes were located in a 19kb Bam HI fragment in the order thyA recC recB argA , so far as estimated. The recA recB recC cells harboring plasmid subcloned with this Bam HI fragment exhibited 12.3-fold increase in recBC DNase activity. Clones carrying the recB and the recC gene expressed recB and recC function, respectively, and the initiation sites of transcription of these genes were detected by S1 nuclease mapping, proving that the recB and recC genes consist of independent cistrons.