HETEROLOGOUS EXPRESSION OF THE BACTERIOCIN MESENTERICIN Y105 USING THE DEDICATED TRANSPORT-SYSTEM AND THE GENERAL SECRETION PATHWAY

Two different N-terminal extensions have been identified within class II bacteriocin precursors. The first one is a two-glycine-type leader peptide associated with a dedicated ATP-binding cassette transporter. The second is a signal peptide which directs the bacteriocin precursor to the general secretion machinery. Mesentericin Y105 is a class II a nti-listeria bacteriocin produced by Leuconostoc mesenteroides Y105 vi a a dedicated transport system (DTS), To investigate heterologous expr ession systems capable of producing mesentericin Y105 in various hosts , two different secretion vectors were constructed. One of them, conta ining the mesentericin Y105 structural gene fused to the segment encod ing the divergicin A signal peptide, was introduced into Escherichia c oli, Leuconostoc subsp, and Lactococcus subsp, In E. coli, mesenterici n Y105 production was linked to a putative periplasmic toxicity. To ta ke advantage of this secretion system, the mesentericin Y105 precursor was also produced in E, coli, It was demonstrated that this pre-bader iocin exhibited some antagonistic activity against Listeria. To allow for a comparison between the two different transport systems, mesenter icin Y105 production using the vector containing the mesentericin Y105 structural gene and its DTS transporter operon was examined. The prod uction of mesentericin Y105 was monitored by a new fast purification m ethod followed by MS analysis. It was shown that, in Leuconostoc, the production of mesentericin Y105 is enhanced via the DTS compared to th e general secretion pathway.