Role of GbpA protein, an important virulence-related colonization factor, forVibrio cholerae's survival in the aquatic environment
N-acetyl glucosamine-binding protein A (GbpA) is a chitin binding protein and a virulence factor involved in the colonization of human intestine. We investigated the distribution and genetic variations ofgbpAin 488V. choleraestrains of environmental and clinical origin, belonging to different serogroups and biotypes. We found that the gene is consistently present and highly conserved including an environmentalV. cholerae-related strain of ancestral origin. The gene was also consistently expressed in a number of representativeV. choleraestrains cultured in laboratory aquatic microcosms under conditions simulating those found in temperate marine environments. Functional analysis carried out onV. choleraeO1 El Tor N16961 showed that GbpA is not involved in adhesion to inorganic surfaces but promotes interaction with environmental biotic substrates (plankton and bivalve hepatopancreas cells) representing known marine reservoir or host for the bacterium. It is suggested that the ability of GbpA to colonize human intestinal cells most probably originated from its primary function in the aquatic environment.