3rf3
From Proteopedia
Shigella IpaA-VBS3 in complex with human vinculin
Structural highlights
Disease[VINC_HUMAN] Defects in VCL are the cause of cardiomyopathy dilated type 1W (CMD1W) [MIM:611407]. Dilated cardiomyopathy is a disorder characterized by ventricular dilation and impaired systolic function, resulting in congestive heart failure and arrhythmia. Patients are at risk of premature death.[1] [2] Defects in VCL are the cause of familial hypertrophic cardiomyopathy type 15 (CMH15) [MIM:613255]. It is a hereditary heart disorder characterized by ventricular hypertrophy, which is usually asymmetric and often involves the interventricular septum. The symptoms include dyspnea, syncope, collapse, palpitations, and chest pain. They can be readily provoked by exercise. The disorder has inter- and intrafamilial variability ranging from benign to malignant forms with high risk of cardiac failure and sudden cardiac death.[3] Function[VINC_HUMAN] Actin filament (F-actin)-binding protein involved in cell-matrix adhesion and cell-cell adhesion. Regulates cell-surface E-cadherin expression and potentiates mechanosensing by the E-cadherin complex. May also play important roles in cell morphology and locomotion.[4] [IPAA_SHIFL] Rapidly associates with the first 265 amino acids of vinculin after bacteria-cell contact. This interaction is critical for efficient Shigella uptake. IpaA acts as a potent activator of vinculin and increase its ability to interact with F-actin. The complex IpaA-vinculin induces F-actin depolymerization along with the occasional formation of actin filament bundles.[5] [6] Publication Abstract from PubMedInternalization of Shigella into host epithelial cells, where the bacteria replicates and spreads to neighboring cells, requires a type 3 secretion system (T3SS) effector coined IpaA. IpaA binds directly to and activates the cytoskeletal protein vinculin after injection in the host cell cytosol, and this was previously thought to be directed by two amphipathic alpha-helical vinculin-binding sites (VBS) found in the C-terminal tail domain of IpaA. Here, we report a third VBS, IpaA-VBS3, that is located N-terminal to the other two VBSs of IpaA and show that one IpaA molecule can bind up to three vinculin molecules. Biochemical in vitro Shigella invasion assays and the 1.6 A crystal structure of the vinculin.IpaA-VBS3 complex showed that IpaA-VBS3 is functionally redundant with the other two IpaA-VBSs in cell invasion and in activating the latent F-actin binding functions of vinculin. Multiple VBSs in IpaA are reminiscent of talin, which harbors 11 VBSs. However, most of the talin VBSs have low affinity and are buried in helix bundles, whereas all three of the VBSs of IpaA are high affinity, readily available, and in close proximity to each other in the IpaA structure. Although deletion of IpaA-VBS3 has no detectable effects on Shigella invasion of epithelial cells, deletion of all three VBSs impaired bacterial invasion to levels found in an ipaA null mutant strain. Thus, IpaA-directed mimicry of talin in activating vinculin occurs through three high affinity VBSs that are essential for Shigella pathogenesis. Novel vinculin binding site of the IpaA invasin of Shigella.,Park H, Valencia-Gallardo C, Sharff A, Tran Van Nhieu G, Izard T J Biol Chem. 2011 Jul 1;286(26):23214-21. Epub 2011 Apr 27. PMID:21525010[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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Categories: Homo sapiens | Shigella flexneri | Izard, T | Park, H | Sharff, A | Alpha-helix bundle domain | Bacterial toxin | Cell adhesion | Cytoskeletal protein | Cytoskeleton | Cytosol | F-actin | Focal adhesion | Ipaa | Pathogen-host interaction | Phosphatidylinositol 4 5-bisphosphate | Protein binding-toxin complex | Protein-protein interaction | Talin
