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Neural Wiskott-Aldrich syndrome protein is implicated in the actin-based motility of Shigella flexneri
1Department of Bacteriology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Abstract:
Shigella, the causative agent of bacillary dysentery, is capable of directing its own movement in the cytoplasm of infected epithelial cells. The bacterial surface protein VirG recruits host components mediating actin polymerization, which is thought to serve as the propulsive force. Here, we show that neural Wiskott-Aldrich syndrome protein (N-WASP), which is a critical target for filopodium formation downstream of Cdc42, is required for assembly of the actin tail generated by intracellular S.flexneri. N-WASP accumulates at the front of the actin tail and is capable of interacting with VirG in vitro and in vivo, a phenomenon that is not observed in intracellular Listeria monocytogenes. The verprolin-homology region in N-WASP was required for binding to the glycine-rich repeats domain of VirG, an essential domain for recruitment of F-actin on intracellular S.flexneri. Overexpression of a dominant-negative N-WASP mutant greatly inhibited formation of the actin tail by intracellular S.flexneri. Furthermore, depletion of N-WASP from Xenopus egg extracts shut off Shigella actin tail assembly, and this was restored upon addition of N-WASP protein, suggesting that N-WASP is a critical host factor for the assembly of the actin tail by intracellular Shigella.
Insights
Neural Wiskott-Aldrich syndrome protein (N-WASP) is essential for Shigella
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Shigella flexneri causes bacillary dysentery by moving within host cells.
- Bacterial protein VirG recruits host factors to drive actin polymerization for propulsion.
Purpose of the Study:
- To investigate the role of neural Wiskott-Aldrich syndrome protein (N-WASP) in Shigella actin tail formation.
- To elucidate the interaction between Shigella VirG and host N-WASP.
Main Methods:
- Investigated N-WASP's role in S. flexneri actin tail assembly using in vitro and in vivo assays.
- Utilized dominant-negative N-WASP mutants and depletion/repletion experiments in Xenopus egg extracts.
- Examined protein-protein interactions between VirG and N-WASP.
Main Results:
- N-WASP accumulates at the leading edge of the actin tail and interacts with Shigella VirG.
- The verprolin-homology region of N-WASP binds to VirG's glycine-rich repeats.
- Inhibition or depletion of N-WASP significantly impaired Shigella actin tail formation.
Conclusions:
- N-WASP is a critical host factor required for the assembly of actin tails by intracellular Shigella.
- N-WASP facilitates Shigella motility within host cells by mediating actin polymerization.
- The interaction between VirG and N-WASP is specific to Shigella and crucial for its intracellular movement.