The VirG (IcsA) protein of Shigella is required for recruitment of host actin filament (F-actin) by intracellularly motile bacteria. An N-terminal 80-kDa VirG portion (α-domain) is exposed on the bacterial surface, while the following C-terminal 37-kDa portion (β-core) is embedded in the outer membrane. Here, we report that the surface exposed α-domain of VirG possesses two distinct functional domains; one is the N-terminal two-thirds portion of the α-domain which is required for eliciting F-actin assembly on the bacteria in infected cells, and the other one is the rest of the C-terminal portion of the VirG α-domain, which is essential for the asymmetric distribution of VirG on the bacterial surface. Furthermore, we found that vinculin, an actin-binding cytoskeletal protein, accumulates on the surface of bacteria expressing VirG in infected cells, and that the distribution of vinculin coincided with the distribution of VirG and assembled F-actin. The vinculin accumulation depended on the expression of the α-domain VirG portion required for F-actin assembly, but the recruitment of vinculin on Shigella appeared prior to the appearance of F-actin in the infected cells. Analysis of proteins interacting with VirG using Xenopus laevis eggs extracts revealed that vinculin was a protein that bound to the α-domain portion. This was further confirmed using purified chicken gizzard vinculin, in that the 95-kDa vinculin head part, but not the 30-kDa tail part, directly bound to the α-domain portion. These results suggest a possible role for vinculin in recruitment of F-actin to the VirG moiety exposed on Shigella in infected mammalian cells.
Functional Analysis of Shigella VirG Domains Essential for Interaction with Vinculin and Actin-based Motility*
Toshihiko Suzuki,S. Saga,C. Sasakawa
Published 1996 in Journal of Biological Chemistry
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- Publication year
1996
- Venue
Journal of Biological Chemistry
- Publication date
1996-09-06
- Fields of study
Biology, Medicine
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
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