Isolation and characterization of kinC, a gene that encodes a sensor kinase homologous to the sporulation sensor kinases KinA and KinB in Bacillus subtilis

Abstract

Phosphorylation of the transcription factor encoded by spo0A is required for the initiation of sporulation in Bacillus subtilis. Production and accumulation of Spo0A-P is controlled by histidine protein kinases and the spo0 gene products. To identify additional genes that might be involved in the initiation of sporulation and production of Spo0A-P, we isolated genes which when present on a multicopy plasmid could suppress the sporulation defect of a spo0K mutant. kinC was one gene isolated in this way. A multicopy plasmid containing kinC completely or partially suppressed the sporulation defect caused by mutations in spo0K, kinA, spo0F, and spo0B, indicating that at least when overexpressed, KinC is capable of stimulating phosphorylation of Spo0A independently of the normal phosphorylation pathway. The predicted product of kinC is 428 amino acids long and is most similar to KinA and KinB, the histidine protein kinases involved in the initiation of sporulation. In otherwise wild-type strains, kinC null mutations caused little or no defect in sporulation under the conditions tested. However, in the absence of a functional phosphorelay (spo0F or spo0B), KinC appears to be the kinase responsible for phosphorylation of the sof-1 and rvtA11 forms of Spo0A.