Figure 1.

Alignment of putative cysteine protease domains. (A) Phylogenetic tree of 19 putative CPDs and (B) CLUSTALW alignment of five diverse sequences. ^†Symbol in phylogenetic tree indicates diverse sequences selected for alignment in (B). In (B), asterisks in consensus sequence represent conserved residues in 3/5 sequences and capital letters represent 100% identity. Outlined dipeptide sequence indicates cleavage sites determined experimentally. CPDs were identified within nine Vibrio-type RTX toxins from V. cholerae (VcRtx); V. vulnificus (VvRtx), V. splendidus (VsRtx), Xenorhabdus nematophila (XnRtx), X. bovienii (XbRtx), and Photorhabdus luminescens (Plu1344, Plu1341, Plu3217, and Plu3324); four clostridial toxins, specifically C. difficile toxin A (TcdA), toxin B (TcdB), C. sordellii cytotoxin L (TcsL), and C. noveyi alpha toxin (TcnA); two putative Yersinia toxins Y. pseudotuberculosis YPTB3219 (YpRtx) and Y. mollaretti Mfp2 (YmMfp2); and four domains arranged in tandem in B. pertussis putative adhesin FhaL (FhaL1-4).