THE SIGNAL PEPTIDASE-II (LSP) GENE OF BACILLUS-SUBTILIS

The gene encoding the type II signal peptidase (SPase III) of Bacillus subtilis was isolated by screening a genomic DNA library of this bact erium for the ability of increase the levels of globomycin resistance in Escherichia coli, and to complement the growth deficiency at the no n-permissive temperature of E. coli strain Y815 carrying a temperature -sensitive mutation its lsp gene for SPase II. The deduced amino acid sequence of the B. subtilis SPase II showed significant similarity wit h those of other known SPase II enzymes. Activity of the B. subtilis S Pase II was demonstrated by a pulse-labelling experiment in E. coli. I n B. subtilis, the Isp gene is flanked by the isoleucyl-tRNA synthetas e (ileS) gene and the pyrimidine biosynthetic (pyr) gene cluster, whic h is known to map at 139 degrees C of the chromosome. In the Gram-posi tive bacteria studied thus far Isp appears to be the first gene in an operon. The promoter-distal gene ('orf4') of this operon specifies a h ypothetical protein in bacteria and yeast.