IDENTIFICATION OF TLPC, A NOVEL 62-KDA MCP-LIKE PROTEIN FROM BACILLUS-SUBTILIS

We report the sequence and characterization of the Bacillus subtilis t lpC gene. tlpC encodes a 61.8 kDa polypeptide (TlpC) which exhibits 30 % amino acid identity with the Escherichia coil methyl-accepting chemo taxis proteins (MCPs) and 38% identity with B. subtilis MCPs within th e C-terminal domain. The putative methylation sites parallel those of the B. subtilis MCPs, rather than those of the E. coil receptors. TlpC is methylated both in vivo and in vitro although the level of methyla tion is poor. In addition, the E. coil anti-Trg antibody is shown to c ross-react with this membrane protein. Inactivation of the tlpC gene c onfirms that TlpC is not one of the previously characterized MCPs from B. subtilis. Capillary assays were performed using a variety of chemo effectors, which included all 20 amino acids, several sugars, and seve ral compounds previously classified as repellents. However, no chemota ctic defect was observed for any of the chemoeffectors tested. We sugg est that TlpC is similar to an evolutionary intermediate from which th e major chemotactic transducers from B. subtilis arose.