Identification and nucleotide sequence of genes involved in the synthesis of lactocin 705, a two-peptide bacteriocin from Lactobacillus casei CRL 705

The structural gene determinants of lactocin 705, a bacteriocin produced by Lacrobacillus casei CRL 705, have been amplified from a plasmid of approxi mately 35 kb and sequenced. Lactocin 705 is a class IIb bacteriocin, whose activity depends upon the complementation of two peptides (705 alpha and 70 5 beta) of 33 amino acid residues each. These peptides are synthesized as p recursors with signal sequences of the double-glycine type, which exhibited high identities with the leader peptides of plantaricin S and J from Lacto bacillus plantarum, brochocin C from Brochotrix campestris, sakacin P from Lactobacillus sake, and the competence stimulating peptides from Streptococ cus gordonii and Streptococcus mitis. However, the two mature bacteriocins 705 alpha and 705 beta do not show significant similarity to other sequence s in the databases. (C) 2000 Published by Elsevier Science B.V. All rights reserved.