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Microbiology. 2012 Jul;158(Pt 7):1874-1883. doi: 10.1099/mic.0.056465-0. Epub 2012 Apr 19.

Self-association of the Shigella flexneri IcsA autotransporter protein.

Author information

1
Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, South Australia, Australia.
2
Discipline of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, South Australia, Australia.

Abstract

The IcsA autotransporter protein is a major virulence factor of the human intracellular pathogen Shigella flexneri. IcsA is distributed at the poles in the outer membrane (OM) of S. flexneri and interacts with components of the host actin-polymerization machinery to facilitate intracellular actin-based motility and subsequent cell-to-cell spreading of the bacterium. We sought to characterize the biochemical properties of IcsA in the bacterial OM. Chemical cross-linking data suggested that IcsA exists in a complex in the OM. Furthermore, reciprocal co-immunoprecipitation of differentially epitope-tagged IcsA proteins indicated that IcsA is able to self-associate. The identification of IcsA linker-insertion mutants that were negatively dominant provided genetic evidence of IcsA-IcsA interactions. From these results, we propose a model whereby IcsA self-association facilitates efficient actin-based motility.

PMID:
22516224
DOI:
10.1099/mic.0.056465-0
[Indexed for MEDLINE]

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