title: Characterization of the ysa pathogenicity locus in the chromosome of Yersinia enterocolitica and phylogeny analysis of type III secretion systems.
abstract: Several Gram negative bacteria use a complex system called "type III secretion system" (TTSS) to engage their host. The archetype of TTSS is the plasmid-encoded "Yop virulon" shared by the three species of pathogenic Yersinia (Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica). A second TTSS, called Ysa (for Yersinia secretion apparatus) was recently described in Y. enterocolitica 8081, a strain from serotype O:8. In this study, we describe the ysa locus from A127/90, another strain of serotype O:8, and we extend the sequence to several new genes encoding Ysp proteins which are the substrates of this secretion system, and a putative chaperone SycB. According to the deduced protein sequences, the ysa system from A127/90 is identical to that of 8081. It is different from the chromosome-encoded TTSS of Y. pestis but is instead closely related to the Mxi-Spa TTSS of Shigella and to the SPI-1 encoded TTSS of Salmonella enterica. We further demonstrated that the ysa locus is only present in biotype IB strains of Y. enterocolitica. Including this new Ysa system, a phylogenetic analysis of the 26 known TTSSs was carried out, based on the sequence analysis of three conserved proteins. All the TTSSs fall into five different clusters. The phylogenetic tree of these TTSSs is completely different from the evolutionary tree based on 16S RNA, indicating that TTSSs have been distributed by horizontal transfer.
authors.affiliation: Microbial Pathogenesis Unit, Christian de Duve Institute of Cellular Pathology and Faculté de Médecine, Université Catholique de Louvain, Belgium.
authors.forename: Boris
authors.initials: B
authors.lastname: Foultier
authors.forename: Paul
authors.initials: P
authors.lastname: Troisfontaines
authors.forename: Simone
authors.initials: S
authors.lastname: Müller
authors.forename: Fred R
authors.initials: FR
authors.lastname: Opperdoes
authors.forename: Guy R
authors.initials: GR
authors.lastname: Cornelis
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D014774:Virulence / Q000235:genetics*; D015008:Yersinia enterocolitica / Q000145:classification* / Q000235:genetics* / Q000472:pathogenicity*; D015010:Yersinia pestis / Q000235:genetics / Q000472:pathogenicity; D015011:Yersinia pseudotuberculosis / Q000235:genetics / Q000472:pathogenicity
chemical_list: D017931:DNA Primers