ABSTRACTThe objective of this study was to analyze multifunctional autoprocessing repeats-in-toxin (MARTX) toxin domain organization within the aquatic speciesVibrio vulnificusas well as to study the evolution of thertxA1gene. The species is subdivided into three biotypes that differ in host range and geographical distribution. We have found three different types (I, II, and III) ofV. vulnificusMARTX (MARTXVv) toxins with common domains (an autocatalytic cysteine protease domain [CPD], an α/β-hydrolase domain, and a domain resembling that of the LifA protein ofEscherichia coliO127:H6 E2348/69 [Efa/LifA]) and specific domains (a Rho-GTPase inactivation domain [RID], a domain of unknown function [DUF],a domain resembling that of thertxAprotein ofPhotorhabdus asymbiotica[rtxAPA], and an actin cross-linking domain [ACD]). Biotype 1 isolates harbor MARTXVvtoxin types I and II, biotype 2 isolates carry MARTXVvtoxin type III, and biotype 3 isolates have MARTXVvtoxin type II. The analyzed biotype 2 isolates harbor two identical copies ofrtxA1, one chromosomal and the other plasmidic. The evolutionary history of the gene demonstrates that MARTXVvtoxins are mosaics, comprising pieces with different evolutionary histories, some of which have been acquired by intra- or interspecific horizontal gene transfer. Finally, we have found evidence that the evolutionary history of thertxA1gene for biotype 2 differs totally from the gene history of biotypes 1 and 3.
Glycan Specificity of the Vibrio vulnificus Hemolysin Lectin Outlines Evolutionary History of Membrane Targeting by a Toxin Family