STABILITY AND FUNCTION OF THE SIGNAL PEPTIDE OF THE PCLODF13-DERIVED BACTERIOCIN RELEASE PROTEIN

The pCloDF13-derived bacteriocin release protein (BRP) is synthesized as a prelipoprotein with a signal peptide which remains stable after p rocessing. This signal peptide accumulates in the cytoplasmic membrane and is, together with the mature BRP, required for efficient release of cloacin DF13. We investigated the structural requirements for stabi lity of the BRP signal peptide by constructing hybrid signal peptides consisting of parts of the BRP and Lpp signal peptides. Signal peptide stability was investigated by pulse-labelling and pulse-chase experim ents. To study the functioning of the BRP signal peptide, the hybrid c onstructs were tested for their ability to promote BRP-mediated cloaci n DF13-release and their ability to affect the viability of the host c ells. The results obtained suggest that the N-terminal part of the BRP signal peptide together with the C-terminal alanine residue are impor tant far stability. When expressed as a separate entity, all mutant si gnal peptides that contain a part of the BRP signal peptide are capabl e of affecting cell viability. The results indicated a possible correl ation between stability of the BRP signal peptide and cloacin DF13-rel ease.