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 subtilis secA gene as a probe. The S. carnosus secA encodes a polypeptide of 844 amino acid residues which is homologous to other known SecA proteins. 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 an Escherichia coli secA mutant could not be complemented by the S. carnosus SecA protein. Our results suggest that the interactions of SecA with precursor proteins and/or other components of bacterial preprotein translocase are optimized within each organism.