Structural highlights
Function
[SIPA_SALTY] Actin-binding protein that interferes with host cell actin cytoskeleton. It stimulates actin polymerization and counteracts F-actin destabilizing proteins. Potentiates SipC activity; both are required for an efficient bacterial internalization. In vitro, forms a complex with host cell protein T-plastin increasing actin bundling. It inhibits ADF/cofilin-directed depolymerization both by preventing binding of ADF and cofilin and by displacing them from F-actin. Also protects F-actin from gelsolin-directed severing and reanneals gelsolin-severed F-actin fragments.[1] [2]
Publication Abstract from PubMed
Like many bacterial pathogens, Salmonella spp. use a type III secretion system to inject virulence proteins into host cells. The Salmonella invasion protein A (SipA) binds host actin, enhances its polymerization near adherent extracellular bacteria, and contributes to cytoskeletal rearrangements that internalize the pathogen. By combining x-ray crystallography of SipA with electron microscopy and image analysis of SipA-actin filaments, we show that SipA functions as a "molecular staple," in which a globular domain and two nonglobular "arms" mechanically stabilize the filament by tethering actin subunits in opposing strands. Deletion analysis of the tethering arms provides strong support for this model.
Salmonella SipA polymerizes actin by stapling filaments with nonglobular protein arms.,Lilic M, Galkin VE, Orlova A, VanLoock MS, Egelman EH, Stebbins CE Science. 2003 Sep 26;301(5641):1918-21. PMID:14512630[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Zhou D, Mooseker MS, Galan JE. Role of the S. typhimurium actin-binding protein SipA in bacterial internalization. Science. 1999 Mar 26;283(5410):2092-5. PMID:10092234
- ↑ McGhie EJ, Hayward RD, Koronakis V. Control of actin turnover by a salmonella invasion protein. Mol Cell. 2004 Feb 27;13(4):497-510. PMID:14992720
- ↑ Lilic M, Galkin VE, Orlova A, VanLoock MS, Egelman EH, Stebbins CE. Salmonella SipA polymerizes actin by stapling filaments with nonglobular protein arms. Science. 2003 Sep 26;301(5641):1918-21. PMID:14512630 doi:http://dx.doi.org/10.1126/science.1088433
