OspE2 of Shigella sonnei Is Required for the Maintenance of Cell Architecture of Bacterium-Infected Cells

Abstract

The OspE2 product of Shigella spp., the expression of which is regulated by the mxiE gene, is secreted through a type III secretion system into host cells. We investigated the function of OspE2 of Shigella sonnei by using cultured epithelial cells. Cells invaded by an ospE2 deletion mutant altered their morphology into the rounding shape, which was not due to cell death, whereas cells invaded by the wild-type strain kept their cell shape intact. The ospE2 mutation did not affect initial cell entry and multiplication in cells, but the mutant formed smaller-than-normal plaques on cell monolayers, indicating a deficiency in cell-to-cell spread by the bacteria. An mxiE deletion mutant also showed changes in cell morphology and deficiency in bacterial spread to adjacent cells. In cells invaded by the ospE2 mutant, disturbance of actin stress fibers was prominent at 3 h after invasion. Analysis of OspE2 localization indicated that the OspE2 protein accumulated on focal contactlike structures in the infected host cells. These results suggest that colocalization of the OspE2 protein in the focal contacts of infected cells may function to maintain an intact cell morphology. The morphological change induced by invasion of the ospE2 mutant may affect secondary bacterial transmission.

Systematic Analysis of Bacterial Effector-Postsynaptic Density 95/Disc Large/Zonula Occludens-1 (PDZ) Domain Interactions Demonstrates Shigella OspE Protein Promotes Protein Kinase C Activation via PDLIM Proteins

“…We tested whether OspE1/E2 co-localized with PDLIM family members in mammalian cells. The pattern of EGFP-OspE1 signal was consistent with its localization to focal adhesions, as was reported previously (20). EGFP-OspE1 showed no co-localization with PDLIM3-Myc, but partial colocalization with PDLIM7-Myc, at sites that appeared to be restricted to the junction of focal adhesions with stress fibers (Fig.…”

“…Are Important for Intercellular Spread of S. flexneri-Whereas S. flexneri encodes two intact copies of ospE, ospE1 and ospE2, Shigella sonnei encodes only a single intact ospE, which is required for efficient intercellular spread through mammalian cell monolayers (18,20). We found that in S. flexneri, OspE1 and OspE2 are redundant with respect to intercellular spread, as strains carrying a deletion of either one or the other ospE gene alone displayed no significant defect, whereas a strain carrying a deletion of both genes displayed a 35-45% reduction in spread (Fig.…”

An extensive repertoire of type III secretion effectors in Escherichia coli O157 and the role of lambdoid phages in their dissemination

“…(34). OspE2 has recently been shown to be required for the maintenance of cell architecture of Shigella-infected cells (35). We found EspO1-1 to be translocated in all of our assays (Table 1).…”

How Do the Virulence Factors of Shigella Work Together to Cause Disease?

“…They are capable of functioning redundantly, however in S. sonnei, ospE1 is a pseudogene (Miura et al, 2006). An ospE2 − knockout caused cellular rounding that was not as a result of apoptosis or necrosis, and wild-type phenotype was restored when ospE2 knockouts were complemented with functioning ospE2 encoded on a plasmid (Miura et al, 2006). OspEs are capable of interacting with integrin-linked kinase (ILK), which is found in the membrane of host cells where it reinforces focal adhesions (Kim et al, 2009).…”