Neural Wiskott-Aldrich syndrome protein (N-WASP) is the specific ligand for Shigella VirG among the WASP family and determines the host cell type allowing actin-based spreading.
Shigella, the causative agent of bacillary dysentery, is capable of directing its movement within host cells by forming an actin comet tail. The VirG (IcsA) pro-tein expressed at one pole of the bacterium recruits neural Wiskott-Aldrich syndrome protein (N-WASP), a member of the WASP family, which in turn stimulates actin-related protein (Arp) 2/3 complex-mediated actin polymerization. As all the WASP family proteins induce actin polymerization by recruiting Arp2/3 complex, we investigated their involvement in Shigella motility. Here, we show that VirG binds to N-WASP but not to the other WASP family proteins. Using a series of chimeras obtained by swapping N-WASP and WASP domains, we demonstrated that the specificity of VirG to interact with N-WASP lies in the N-terminal region containing the pleckstrin homology (PH) domain and calmodulin-binding IQ motif of N-WASP. A conformational change in N-WASP was important for the VirG-N-WASP interaction, as elimination of the C-terminal acidic region, which is responsible for the intramolecular interaction with the central basic region of N-WASP, affected the specific binding to VirG. We observed that, in haematopoietic cells such as macrophages, polymorphonuclear leucocytes (PMNs) and platelets, WASP was predominantly expressed, whereas the expression of N-WASP was greatly suppressed. Indeed, unlike Listeria, Shigella was unable to move in macrophages at all, although the movement was restored as N-WASP was expressed ectopically. Thus, our findings demonstrate that N-WASP is a specific ligand of VirG, which determines the host cell type allowing actin-based spreading of Shigella.
Suzuki
Toshihiko
T
PRESTO, Japan Science and Technology Corporation (JST), Japan.
Mimuro
Hitomi
H
Suetsugu
Shiro
S
Miki
Hiroaki
H
Takenawa
Tadaomi
T
Sasakawa
Chihiro
C
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins; D001692:Biological Transport; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008264:Macrophages / Q000378:metabolism / Q000382:microbiology; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D012760:Shigella / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal
D000199:Actins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D008024:Ligands; D009419:Nerve Tissue Proteins; D014157:Transcription Factors; C495771:WASL protein, human; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; C058483:virG protein, Shigella flexneri