Fig 2.

Alignment of the amino acid sequences representing the three clusters of ChxA (ChxA I, II and III) from V. cholerae strains. Only one ChxA sequence from each cluster, along with the published prototype sequence (AY876053), is shown here for simplicity. The ChxA I sequences are identical or similar to prototype ChxA. The ChxA II sequences clearly define the amino acid changes in the receptor binding domain (RBD) and ChxA III in the catalytic domain (CD). All the sequences of ChxA II possess an identical deletion of 6 amino acids (GLALCW) in the RBD, and 6 sequences have a 5-amino-acid (AIAKE) insertion in CD. ChxA I and II possess KDEL whereas ChxA III possesses an HDEL signal peptide at the C-terminal end. Serine-to-glycine substitution can be observed at the P5 position of the furin binding site in ChxA III. *, conserved amino acid residue critical for catalytic activity. Matching amino acids are indicated by dots and deleted ones by dashes.