Polyphosphate Kinase 1 Is a Pathogenesis Determinant in Enterohemorrhagic O157:H7

The gene encodes polyphosphate kinase (PPK1), which is the major catalytic enzyme that utilizes to synthesize inorganic polyphosphate (polyP). The aim of this study was to explore the role of PPK1 in the pathogenesis of Enterohemorrhagic O157:H7 (EHEC O157:H7). An isogenic in-frame deletion mutant (Δ) and complemented mutant () were constructed and characterized in comparison to wild-type (WT) EHEC O157:H7 strain EDL933w by microscope observation and growth curve analysis. Survival rates under heat stress and acid tolerance, both of which the bacteria would face during pathogenesis, were compared among the three strains. LoVo cells and a murine model of intestinal colitis were used as the and models, respectively, to evaluate the effect of PPK1 on adhesion and invasion during the process of pathogenesis. Real-time reverse-transcription PCR of regulatory gene , adhesion gene , and toxin genes and was carried out to corroborate the results from the and models. The deletion mutant exhibited disrupted polyP levels, but not morphology and growth characteristics. The survival rate of the Δ strain under stringent environmental conditions was lower as compared with WT and The assays showed that deletion of the gene reduced the adhesion, formation of attaching and effacing (A/E) lesions, and invasive ability of EHEC O157:H7. Moreover, the virulence of the Δ in BALB/c mice was weaker as compared with the other two strains. Additionally, mRNA expression of , , and were consistent with the and results. In conclusion: EHEC O157:H7 requires PPK1 for both survival under harsh environmental conditions and virulence .