CHEMOTAXIS IN BACILLUS-SUBTILIS REQUIRES EITHER OF 2 FUNCTIONALLY REDUNDANT CHEW HOMOLOGS

We have characterized mutants in a novel gene of Bacillus subtilis, ch eV, which encodes a protein homologous to both CheW and CheY. A null m utant in cheV is only slightly defective in capillary and tethered cel l assays. However, a double mutant lacking both CheV and CheW has a st rong tumble bias, does not respond to addition of attractant, and show s essentially no accumulation in capillary assays. Thus, CheV and CheW appear in part to be functionally redundant. A strain lacking CheW an d expressing only the CheW domain of CheV is chemotactic, suggesting t hat the truncated CheV protein retains in vivo function. We speculate that CheV and CheW function together to couple CheA activation to meth yl-accepting chemotaxis protein receptor status and that possible CheA -dependent phosphorylation of CheV contributes to adaptation.