INDUCIBLE PRODUCTION AND CELLULAR LOCATION OF THE EPIDERMIN BIOSYNTHETIC ENZYME EPIB USING AN IMPROVED STAPHYLOCOCCAL EXPRESSION SYSTEM

The antimicrobial peptide epidermin is distinguished by thioether amin o acids such as meso-lanthionine, 3-methyllanthionine, and 2-aminoviny lcysteine. The enzyme EpiB, encoded on a plasmid of the producing stra in Staphylococcus epidermidis Tu3298, is very likely involved in the f ormation of these unusual amino acids. In order to obtain high-level p roduction of EpiB, an improved staphylococcal expression vector based on the xylose-inducible xy/A promoter of Staphylococcus xylosus was co nstructed. As shown by the expression of a lipase reporter gene, the n ew plasmid pTX15 mediated a considerably higher expression level after induction and a lower background expression level in the uninduced st are than the previously described vector pCX15. The epiB gene was inse rted in pTX15 and expressed in Staphylococcus carnosus. The EpiB prote in was detected both in the cytoplasmic and the membrane fraction and was partially purified in three steps.