Growth phase and low pH affect the thermal regulation of the Yersinia enterocolitica inv gene

Abstract

The inv gene encodes the protein invasin, which is the primary invasion factor for Yersinia enterocolitica in vitro and in vivo. Previous studies of Yersinia species have shown that inv expression and entry into mammalian cells are temperature regulated. Invasin production is reduced at the host temperature of 37 degrees C as compared to production at ambient temperature; consequently, this study was initiated to determine whether other host environmental signals might induce inv expression at 37 degrees C. An inv::phoA translational fusion was recombined on to the Y. enterocolitica chromosome by allelic exchange to monitor inv expression. Molecular characterization of expression of the wild-type inv gene and the inv::phoA fusion showed that invasin is not produced until early stationary phase in bacteria grown at 23 degrees C. Y. enterocolitica grown at 37 degrees C and pH 5.5 showed levels of inv expression comparable to those observed in bacteria grown at 23 degrees C. An increase in Na+ ions caused a slight increase in expression at 37 degrees C. However, expression at 37 degrees C was unaffected by anaerobiosis, growth medium, calcium levels, or iron levels. Additionally, Y. enterocolitica expressed invasin in Peyer's patches two days after being introduced intragastrically into BALB/c mice. These results suggest that invasin expression in Y. enterocolitica may remain elevated early during interaction with the intestinal epithelium, a site at which invasin was shown to be necessary.

Unique Virulence Properties of Yersinia enterocolitica O:3

“…Cell invasion was shown to be solely mediated by the invasin protein, which was highly expressed at 37°C in all YeO:3 isolates, but not in YeO:8 strains (Uliczka et al, 2011). Latter observation is consistent with previous studies, demonstrating that inv expression in YeO:8 strain 8081v is mostly expressed at moderate temperature, whereas only very low amounts of invasin were detectable at 37°C (Pepe et al, 1994).…”

“…This strongly suggests that YadA and invasin of YeO:3 act cooperatively, whereby YadA promotes efficient cell attachment allowing invasin to initiate the entry process (figure 1). These properties seem to be YeO:3 specific, as previous studies with YeO:8 and Y. pseudotuberculosis showed that invasin and YadA are differentially expressed and constitute independent colonization factors that are active at separate sites and/or during different stages of the infection (Eitel & Dersch, 2002;Pepe et al, 1994;Skurnik & Toivanen, 1992).…”

“…These adhesion factors include the chromosomally encoded outer membrane protein invasin (Inv). Invasin is predominantly expressed at moderate temperature in vitro, and can be induced at 37°C under certain growth conditions (Pepe et al, 1994). Invasin binds with high affinity to β 1 -integrins and induces uptake into host cells (Isberg et al, 1987;Pepe & Miller, 1993).…”

A new pathway for the secretion of virulence factors by bacteria: The flagellar export apparatus functions as a protein-secretion system

“…Nonspecific antibodies were removed by adsorption of the sera with an acetone powders prepared from a cultures of Y. enterocolitica YEDS10 and E. coli containing pMAL-p2 (17). Polyclonal sera directed against chloramphenicol acetyl transferase and invasin were described (18,19). Polyclonal sera directed against ␤-lactamase was a gift (K. Postle, Washington State University).…”

Transcriptional Regulation inYersinia: An UpdateYersinia: An Update

“…It was therefore initially proposed that this adhesin contributed only to an acceleration of the early stages of host infection. However, two pieces of evidence suggested that regulation of inv transcription during infection may well depend on stimuli other than temperature (Pepe et al, 1994). Firstly, invasin can still be detected in murine Peyer's patches two days after oral challenge with Y. enterocolitica.…”