Gut proteases target Yersinia invasin in vivo

Abstract

BackgroundYersinia enterocolitica is a common cause of food borne gastrointestinal disease. After oral uptake, yersiniae invade Peyer's patches of the distal ileum. This is accomplished by the binding of the Yersinia invasin to β1 integrins on the apical surface of M cells which overlie follicle associated lymphoid tissue. The gut represents a barrier that severely limits yersiniae from reaching deeper tissues such as Peyer's patches. We wondered if gut protease attack on invasion factors could contribute to the low number of yersiniae invading Peyer's patches.FindingsHere we show that invasin is rapidly degraded in vivo by gut proteases in the mouse infection model. In vivo proteolytic degradation is due to proteolysis by several gut proteases such as trypsin, α-chymotrypsin, pancreatic elastase, and pepsin. Protease treated yersiniae are shown to be less invasive in a cell culture model. YadA, another surface adhesin is cleaved by similar concentrations of gut proteases but Myf was not cleaved, showing that not all surface proteins are equally susceptible to degradation by gut proteases.ConclusionsWe demonstrate that gut proteases target important Yersinia virulence factors such as invasin and YadA in vivo. Since invasin is completely degraded within 2-3 h after reaching the small intestine of mice, it is no longer available to mediate invasion of Peyer's patches.

Enteropathogenic Yersinia spp.

“…Inv and Ail proteins, and the pYV-encoded YadA. After penetration of the intestinal epithelium, yersiniae colonize the Peyer's patches and local lymphoid follicles, and may spread via the lymphatic system or the blood to other tissues, typically to mesenteric lymph nodes, spleen and liver where they form microabscesses (Trcek et al 2011). The ability to survive within these tissues is dependent on the presence of pYV.…”

“…Chromosomally Encoded Virulence Factors Are also Needed Two chromosomal genes, inv and ail, are important for mammalian cell invasion (Trcek et al 2011). The inv gene codes for an outer-membrane invasion protein (Inv) which plays an important role in promoting the entry into epithelial M cells of the ileum during initial …”

Bacterial invasion factors: Tools for crossing biological barriers and drug delivery?

“…Thus, it is not surprising that mainly InvA has been used to test its use for bioinvasive drug carrier systems. Although gut proteases target invasin in vivo [78], it is possible to use smaller and more resistant protein fragments harboring only the invasive domain of…”

“…Use of a longer 497-residue InvA fragment could be also beneficial for uptake, as it induces invasin self-association and  1 -integrins clustering which enhances uptake efficiency [74,88]. On the other hand, a larger InvA fragment might be more prone to degradation by intestinal proteases [78].…”

The Functions of Effector Proteins in Yersinia Virulence

“…Unlike Y. Pestis, these two enteropathogens are commonly transmitted by food or water (Trcek et al, 2011). Multiple studies have indicated the involvement of Yops in the interaction of Yersinia and gut system.…”