Putative bacteriocin proteins encoded by the mcb locus. (A) Amino acid sequence of the predicted McbC proteins encoded by the mcb locus in plasmid pLQ510, M. catarrhalis O12E, and M. catarrhalis V1120. Residues that differ among the proteins are underlined and bolded. (B) Alignment of the amino acid sequence of the putative leader of the M. catarrhalis O12E McbC protein with that of leader peptides of proven and hypothetical double-glycine peptides from other bacteria including CvaC [GenBank: CAA11514] and MchB [GenBank: CAD56170] of E. coli, NMB0091 [GenBank: NP_273152] of Neisseria meningitidis, XF1219 [GenBank:AAF84029] and XF1694 [GenBank: AF84503] of Xylella fastidiosa and LafX [GenBank: AAS08589] of Lactobacillus johnsonii. Highly conserved amino acids are shaded with dark grey. This latter figure is adapted from that published by Michiels et al .