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From Proteopedia
Crystal Structure of Pseudomonas Avirulence Protein AvrPphB
Structural highlights
Function[AVRP3_PSESH] Cysteine protease avirulence protein, which is essential during infection of plant cells from cultivar-specific of beans and Arabidopsis thaliana. The autocleavage of the protein is required for virulence function. May act by affecting the plant defense system. In plants lacking R3 or RPS5 resistance genes, it probably impairs the plant defense system and leads to the bacteria multiplication. In contrast, in plants containing the R3 or RPS5 protein, it is unable to induce disease symptoms, explaining its avirulence name. The 7 kDa product is required for the type-III translocation from Pseudomonas strains to the plant, but are partially dispensable for effector recognition following in planta expression. In infected plants, it probably acts by cleaving the PBS1 protein, which may lead to resistance or disease, depending on the presence or absence of RPS5, respectively.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedAvrPphB is an avirulence (Avr) protein from the plant pathogen Pseudomonas syringae that can trigger a disease-resistance response in a number of host plants including Arabidopsis. AvrPphB belongs to a novel family of cysteine proteases with the charter member of this family being the Yersinia effector protein YopT. AvrPphB has a very stringent substrate specificity, catalyzing a single proteolytic cleavage in the Arabidopsis serine/threonine kinase PBS1. We have determined the crystal structure of AvrPphB by x-ray crystallography at 1.35-A resolution. The structure is composed of a central antiparallel beta-sheet, with alpha-helices packing on both sides of the sheet to form a two-lobe structure. The core of this structure resembles the papain-like cysteine proteases. The similarity includes the AvrPphB active site catalytic triad of Cys-98, His-212, and Asp-227 and the oxyanion hole residue Asn-93. Based on analogy with inhibitor complexes of the papain-like proteases, we propose a model for the substrate-binding mechanism of AvrPphB. A deep and positively charged pocket (S2) and a neighboring shallow surface (S3) likely bind to aspartic acid and glycine residues in the substrate located two (P2) and three (P3) residues N terminal to the cleavage site, respectively. Further implications about the specificity of plant pathogen recognition are also discussed. The crystal structure of Pseudomonas avirulence protein AvrPphB: a papain-like fold with a distinct substrate-binding site.,Zhu M, Shao F, Innes RW, Dixon JE, Xu Z Proc Natl Acad Sci U S A. 2004 Jan 6;101(1):302-7. Epub 2003 Dec 23. PMID:14694194[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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