Proteins of the lactococcin A secretion system: lcnD encodes two in-frame proteins

Polyclonal antibodies were raised against LcnC and LcnD proteins of the Lac tococcus lactis bacteriocin lactococcin A secretory system to examine their cellular location and interaction. Two major reacting bands were detected by Western immunoblot with the anti-LcnD antibody: one of 52 kDa (LcnD) and another of 45 kDa, called here LcnD*. LcnD* was still detectable after rem oving the AUG start codon for LcnD. Chemical cross-linking analyses of memb rane fractions of L. lactis cells expressing the LcnC/D secretion machinery were performed. Our results indicate that LcnD is present in the secretion machinery complex as a dimer and is able to interact with LcnD* and LcnC. (C) 2001 Federation of European Microbiological Societies. Published by Els evier Science B.V. All rights reserved.