The signal peptidase II (Isp) gene of Bacillus subtilis.

The gene encoding the type II signal peptidase (SPase II) of Bacillus subtilis was isolated by screening a genomic DNA library of this bacterium for the ability to increase the levels of globomycin resistance in Escherichia coli, and to complement the growth deficiency at the non-permissive temperature of E. coli strain Y815 carrying a temperature-sensitive mutation in its Isp gene for SPase II. The deduced amino acid sequence of the B. subtilis SPase II showed significant similarity with those of other known SPase II enzymes. Activity of the B. subtilis SPase II was demonstrated by a pulse-labelling experiment in E. coli. In B. subtilis, the Isp gene is flanked by the isoleucyl-tRNA synthetase (ileS) gene and the pyrimidine biosynthetic (pyr) gene cluster, which is known to map at 139 degrees of the chromosome. In the Gram-positive bacteria studied thus far, Isp appears to be the first gene in an operon. The promoter-distal gene ("orf4') of this operon specifies a hypothetical protein in bacteria and yeast.