Abstract
BackgroundYersinia enterocolitica strains responsible for mild gastroenteritis in humans are very diverse with respect to their metabolic and virulence properties. Strain W22703 (biotype 2, serotype O:9) was recently identified to possess nematocidal and insecticidal activity. To better understand the relationship between pathogenicity towards insects and humans, we compared the W22703 genome with that of the highly pathogenic strain 8081 (biotype1B; serotype O:8), the only Y. enterocolitica strain sequenced so far.ResultsWe used whole-genome shotgun data to assemble, annotate and analyse the sequence of strain W22703. Numerous factors assumed to contribute to enteric survival and pathogenesis, among them osmoregulated periplasmic glucan, hydrogenases, cobalamin-dependent pathways, iron uptake systems and the Yersinia genome island 1 (YGI-1) involved in tight adherence were identified to be common to the 8081 and W22703 genomes. However, sets of ~550 genes revealed to be specific for each of them in comparison to the other strain. The plasticity zone (PZ) of 142 kb in the W22703 genome carries an ancient flagellar cluster Flg-2 of ~40 kb, but it lacks the pathogenicity island YAPIYe, the secretion system ysa and yts1, and other virulence determinants of the 8081 PZ. Its composition underlines the prominent variability of this genome region and demonstrates its contribution to the higher pathogenicity of biotype 1B strains with respect to W22703. A novel type three secretion system of mosaic structure was found in the genome of W22703 that is absent in the sequenced strains of the human pathogenic Yersinia species, but conserved in the genomes of the apathogenic species. We identified several regions of differences in W22703 that mainly code for transporters, regulators, metabolic pathways, and defence factors.ConclusionThe W22703 sequence analysis revealed a genome composition distinct from other pathogenic Yersinia enterocolitica strains, thus contributing novel data to the Y. enterocolitica pan-genome. This study also sheds further light on the strategies of this pathogen to cope with its environments.
Highlights
Yersinia enterocolitica strains responsible for mild gastroenteritis in humans are very diverse with respect to their metabolic and virulence properties
The genus Yersinia currently comprises three human pathogens (Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica), and at least 14 species considered harmless for humans, namely Y. aldovae, Y. bercovieri, Y. frederiksenii, Y. intermedia, Y. kristensenii, Y. mollaretii, Y
We have recently shown that strain W22703 confers lethality towards nematodes and Manduca sexta larvae upon oral infection, and that this insecticidal activity is correlated with the presence of the so-called pathogenicity island toxin complex (TC)-PAIYe [13,14]
Summary
Yersinia enterocolitica strains responsible for mild gastroenteritis in humans are very diverse with respect to their metabolic and virulence properties. We have recently shown that strain W22703 (biotype 2, serotype O:9) confers lethality towards nematodes and Manduca sexta larvae upon oral infection, and that this insecticidal activity is correlated with the presence of the so-called pathogenicity island TC-PAIYe [13,14]. This 20 kb-fragment is present in the biotype 2-5 strains, but absent in most biotype 1A and B strains, and carries the toxin complex (TC) genes tcaA, tcaB, tcaC and tccC with homology to TC genes of Photorhabdus luminescens. The absence of TC-PAIYe is not reflected by a loss of toxicity in case of subcutaneous infection, indicating the presence of yet unknown insecticidal determinants in Y. enterocolitica [15]
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