Nucleotide sequence and analysis of plasmid pMD136 from Pediococcus pentosaceus FBB61 (ATCC43200) involved in pediocin A production.

The complete sequence of the 19515-bp plasmid pMD136 from Pediococcus pentosaceus FBB61 (ATCC43200) has been determined. This plasmid is involved in Pediocin A production, a bacteriocin active against a wide range of gram-positive bacteria. It appears to replicate via a theta mechanism, with structures closely related to those of many lactococcal plasmids. Genes homologous to mobilization functions are also present, which are similar in sequence and arrangement to mobA, mobB, and mobC of some staphylococcal plasmids, although the last one contains a deletion in its central part. The region involved in bacteriocin activity has been limited to a 9.4-kb fragment, containing 10 open reading frames organized in a single operon. Since Pediocin A has a molecular weight of about 80 kDa (Piva and Headon, Microbiology, 140, 697-702, 1994), and a gene long enough to encode it is not present in pMD136, it is proposed that genes residing on the plasmid are responsible for the regulation of bacteriocinogenic activity. Gene arrangement and sequence homologies suggest the presence of a two-component-like regulatory mechanism.