A GENE REQUIRED FOR NUTRITIONAL REPRESSION OF THE BACILLUS-SUBTILIS DIPEPTIDE PERMEASE OPERON

An insertion mutation Was isolated that resulted in derepressed expres sion of the Bacillus subtilis dipeptide transport operon (dpp) during the exponential growth phase in rich medium. DNA flanking the site of insertion was found to encode an operon (codVWXY) of four potential op en reading frames (ORFs), The deduced product of the codV ORF is simil ar to members of the lambda Int family; CodW and CodX are homologous t o HsIV and HsIU, two putative heat-shock proteins from Escherichia col i, and to LapC and LapA, two gene products of unknown function from Pa steurella haemolytica, CodX also shares homology with a family of ATPa ses, including ClpX, a regulatory subunit of the E. coli ClpP protease . CodY does not have any homologues in the databases, The insertion mu tation and all previously isolated spontaneous cod mutations were foun d to map in codY. In-frame deletion mutations in each of the other cod genes revealed that only codY is required for repression of dpp in nu trient-rich medium. The codY mutations partially relieved amino acid r epression of the histidine utilization (hut) operon but had no effect on regulation of certain other early stationary phase-induced genes, s uch as spoVG and gsiA.