FUNCTIONAL-CHARACTERIZATION OF THE STAPHYLOCOCCUS-CARNOSUS SECA PROTEIN IN ESCHERICHIA-COLI AND BACILLUS-SUBTILIS SECA MUTANT STRAINS

The Staphylococcus carnosus secA gene was cloned using the Bacillus su btilis secA gene as a probe. The S. carnosus secA encodes a polypeptid e of 844 amino acid residues which is homologous to other known SecA p roteins. The S. carnosus SecA functionally complemented the growth and secretion defects of a temperature-sensitive B. subtilis secA mutant at the non-permissive temperature. In contrast, the growth defect of a n Escherichia coli secA mutant could not be complemented by the S. car nosus SecA protein. Our results suggest that the interactions of SecA with precursor proteins and/or other components of bacterial preprotei n translocase are optimized within each organism.