Identification and characterisation of a novel adhesin Ifp in Yersinia pseudotuberculosis

We termed YPTB1572 Ifp (Intimin family protein) and show that it is able to bind directly to human HEp-2 epithelial cells. Cysteine and tryptophan residues in the C-terminal region of intimin that are essential for function in EPEC and EHEC are conserved in Ifp. Protein binding occurred at distinct foci on the HEp-2 cell surface and can be disrupted by mutation of a single cysteine residue at the C-terminus of the protein. Temporal expression analysis using lux reporter constructs revealed that ifp is expressed at late log phase at 37°C in contrast to invasin, suggesting that Ifp is a late stage adhesin. An ifp defined mutant showed a reduction in adhesion to HEp-2 cells and was attenuated in the Galleria mellonella infection model.A new Y. pseudotuberculosis adhesin has been identified and characterised. This Ifp is a new member in the family of invasin/intimin outer membrane adhesins.Within the genus Yersinia there are three human-pathogenic species; Y. pestis, the causative agent of plague, and two enteric pathogens, Y. pseudotuberculosis and Y. enterocolitica. Despite the differences in disease, Y. pestis and Y. pseudotuberculosis are very closely related at the genetic level. Y. pestis is believed to have evolved from Y. pseudotuberculosis between 1,500-20,000 years ago [1]. Thus, in a remarkably short length of evolutionary time, Y. pestis has evolved from an enteropathogen, to a blood-borne pathogen with an insect vector [2]. Genome sequencing of several Y. pseudotuberculosis and Y. pestis strains, revealed that Y. pestis has accumulated a large number of pseudogenes since its divergence. By the "use it or lose it" paradigm, this is suggestive of the decay of those genes that are no longer required for function as Y. pestis adapts to a new lifestyle [3,4]. Gene disruption may also result in pathoadaptive mutation, whereby loss of gene function results in an increase in virulence [5]. This has been demonstrated in several pathogenic bacteria including Shigella