Elg gene cluster, ElgA amino acid sequence and sequence alignment with type AI prelantibiotics. A, The biosynthetic gene cluster of P. elgii B69 consists of five ORFs, elgT1, elgC, elgT2, elgB, and elgA. The number of amino acids encoded by each gene is indicated below each locus, and the arrows indicate the relative directions of transcription. B, The amino acid sequence of the prepeptide ElgA. C, Sequence alignment of the deduced pre-elgicin (ElgA) with type AI prelantibiotics of nisin (NisA), subtilin (SpaS), epidermin (EpiA), and Pep5 (PepA). The conserved residues are shaded and the cleavage sites of the processing protease are symbolized by vertical solid arrows. The resulting propeptide of the cleaved ElgA in the figure is elgicin C (underlined). ElgA is a type AI prelantibiotic because of the conserved motif "FDLD" in its leader peptide segment and the presence of the genes elgB and elgC.