The marine pathogen Vibrio vulnificus encodes a putative homologue of the Vibrio harveyi regulatory gene, luxR: a genetic and phylogenetic comparison

Vibrio vulnificus is an opportunistic pathogen that exhibits numerous virul ence factors, including the secretion of a zinc metalloprotease and the pro duction of a capsule. We have cloned and sequenced a gene from V. vulnificu s that is a homologue of the positive transcriptional regulator, luxR, of t he lux operon in Vibrio harveyi. This gene encodes a putative, single compl ete open reading frame designated smcR, which shares greater than 75% nucle otide identity with luxR of V. harveyi. The deduced amino acid sequence of the putative SmcR protein is more than 90% identical and 95% similar to tha t of LuxR of V. harveyi, suggesting that V. vulnificus possesses a member o f the family of signal-response genes recently described in Vibrio cholerae and in Vibrio parahaemolyticus . Our data also demonstrate that, in additi on to V. vulnificus, all six Vibrio spp. tested contained genes that hybrid ized with the luxR probe. We also present evidence that this regulatory pro tein was inherited from a common ancestor, and that the gene is ancient and widespread in marine Vibrio spp. (C) 2000 Published by Elsevier Science B. V. All rights reserved.