3ee1
From Proteopedia
Novel fold of VirA, a type III secretion system effector protein from Shigella flexneri
Structural highlights
FunctionVIRA_SHIFL Alpha-tubulin-specific protease that is required for entry into epithelial cells and for subsequent intra- and intercellular spreading. Contributes to bacterial entry into epithelial cells by inducing microtubule (MT) destabilization and the formation of membrane ruffles. The membrane ruffling evoked by VirA results from the activation of host rac1, which is associated with the destruction of MT networks. Creates a tunnel inside the host cell cytoplasm by breaking down the microtubule infrastructure. This facilitates the bacterium's movement through the cytoplasm and also helps other bacteria move faster during the invasion of the eukaryotic cell. Is absolutely required for virulence.[1] [2] [3] Publication Abstract from PubMedVirA, a secreted effector protein from Shigella sp., has been shown to be necessary for its virulence. It was also reported that VirA might be related to papain-like cysteine proteases and cleave alpha-tubulin, thus facilitating intracellular spreading. We have now determined the crystal structure of VirA at 3.0 A resolution. The shape of the molecule resembles the letter "V," with the residues in the N-terminal third of the 45-kDa molecule (some of which are disordered) forming one clearly identifiable domain, and the remainder of the molecule completing the V-like structure. The fold of VirA is unique and does not resemble that of any known protein, including papain, although its N-terminal domain is topologically similar to cysteine protease inhibitors such as stefin B. Analysis of the sequence conservation between VirA and its Escherichia coli homologs EspG and EspG2 did not result in identification of any putative protease-like active site, leaving open a possibility that the biological function of VirA in Shigella virulence may not involve direct proteolytic activity. Novel fold of VirA, a type III secretion system effector protein from Shigella flexneri.,Davis J, Wang J, Tropea JE, Zhang D, Dauter Z, Waugh DS, Wlodawer A Protein Sci. 2008 Dec;17(12):2167-73. Epub 2008 Sep 11. PMID:18787201[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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