YenterocoliticaW22703
Shotgun sequencing of Yersinia enterocolitica strain W22703 biovar 2, serovar O:9: oscillation between invertebrates and mammals
Background: Yersinia enterocolitica strains responsible for mild gastroenteritis in humans are highly diverse with respect to their metabolic and virulence properties. Strain W22703 (biovar 2, serovar 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 (serovar O:8, biovar 1B), the only Y. enterocolitica strain sequenced so far.              Results: We 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 551 and 550 genes revealed to be specific for W22703 and 8081 compared with the other strain. The so-called plasticity zone (PZ) of 142 kb in the W22703 genome carries an ancient flagellar cluster Flg-2 of ~40 kb, but lacks the pathogenicity island YAPIYe, the secretion system ysa and yts1, and other virulence determinants of 8081 PZ. Its composition underlines the high variability of this genome region and demonstrates its contribution to the higher pathogenicity of biovar 1B strains with respect to W22703. A novel type three secretion system (T3SS) of mosaic structure was identified in the genome of strain W22703 that is absent in the human pathogenic Yersinia species, but conserved in the genomes of the apathogenic species. Several regions of differences were identified in W22703 that mainly code for transporters, regulators, metabolic pathways, and defense factors.             Conclusion: The W22703 sequence analysis revealed a genome composition distinct from other pathogenic Yersinia strains, hinting to specific environmental adaptations. This study contributes novel data to the Y. enterocolitica pan-genome and sheds further light on the strategies of this pathogen to cope with its environments.