THE ACCESSORY COLONIZATION FACTOR AND TOXIN-COREGULATED PILUS GENE CLUSTERS ARE PHYSICALLY LINKED ON THE VIBRIO-CHOLERAE-0395 CHROMOSOME

A partial nucleotide sequence of the first gene in the Vibrio cholerae accessory colonization factor gene cluster was obtained by sequencing a cloned acfB::TnphoA fusion junction. Analysis of the sequence data revealed that the ATC start codon of the acfB structural gene is located 6 bp downstream of the tcpJ TCA stop codon. This establishes a large region in excess of 20 kbp of the Vibrio cholerae chromosome as a cluster of coordinately regulated virulence genes involved in intestinal colonization. The absence of a characteristic transcription termination site in the tcpJ-acfB intergenic region indicates that acfB may be encoded on the same messenger RNA as tcpJ. The deduced amino acid sequence for the N-terminal 143 amino acids of AcfB reveals a po- tential leader peptide, that lacks a consensus signal peptidase I recognition sequence. Computer algorithms fail to detect any significant similarities between the partial AcfB amino acid sequence and any entries in the SWISS-PROT database.