| Structural highlights
Function
RD2_PHYIT Effector that enhances P.infestans colonization of Nicotiana benthamiana leaves (PubMed:24632534, PubMed:30329083). Induces a weak Cell death response in N. benthamiana. PexRD2-induced cell death is dependent on SGT1, suggesting that PexRD2 is recognized by the plant immune system (PubMed:19794118). Interacts with the kinase domain of the host MAPKKK epsilon, a positive regulator of cell death associated with plant immunity, and perturbs signaling pathways triggered by MAPKKK epsilon (PubMed:24632534, PubMed:28386988).[1] [2] [3] [4]
Publication Abstract from PubMed
Phytopathogens deliver effector proteins inside host plant cells to promote infection. These proteins can also be sensed by the plant immune system, leading to restriction of pathogen growth. Effector genes can display signatures of positive selection and rapid evolution, presumably a consequence of their co-evolutionary arms race with plants. The molecular mechanisms underlying how effectors evolve to gain new virulence functions and/or evade the plant immune system are poorly understood. Here, we report the crystal structures of the effector domains from two oomycete RXLR proteins, Phytophthora capsici AVR3a11 and Phytophthora infestans PexRD2. Despite sharing <20% sequence identity in their effector domains, they display a conserved core alpha-helical fold. Bioinformatic analyses suggest that the core fold occurs in approximately 44% of annotated Phytophthora RXLR effectors, both as a single domain and in tandem repeats of up to 11 units. Functionally important and polymorphic residues map to the surface of the structures, and PexRD2, but not AVR3a11, oligomerizes in planta. We conclude that the core alpha-helical fold enables functional adaptation of these fast evolving effectors through (i) insertion/deletions in loop regions between alpha-helices, (ii) extensions to the N and C termini, (iii) amino acid replacements in surface residues, (iv) tandem domain duplications, and (v) oligomerization. We hypothesize that the molecular stability provided by this core fold, combined with considerable potential for plasticity, underlies the evolution of effectors that maintain their virulence activities while evading recognition by the plant immune system.
Structures of Phytophthora RXLR Effector Proteins: A CONSERVED BUT ADAPTABLE FOLD UNDERPINS FUNCTIONAL DIVERSITY.,Boutemy LS, King SR, Win J, Hughes RK, Clarke TA, Blumenschein TM, Kamoun S, Banfield MJ J Biol Chem. 2011 Oct 14;286(41):35834-42. Epub 2011 Aug 3. PMID:21813644[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Oh SK, Young C, Lee M, Oliva R, Bozkurt TO, Cano LM, Win J, Bos JI, Liu HY, van Damme M, Morgan W, Choi D, Van der Vossen EA, Vleeshouwers VG, Kamoun S. In planta expression screens of Phytophthora infestans RXLR effectors reveal diverse phenotypes, including activation of the Solanum bulbocastanum disease resistance protein Rpi-blb2. Plant Cell. 2009 Sep;21(9):2928-47. PMID:19794118 doi:10.1105/tpc.109.068247
- ↑ King SR, McLellan H, Boevink PC, Armstrong MR, Bukharova T, Sukarta O, Win J, Kamoun S, Birch PR, Banfield MJ. Phytophthora infestans RXLR effector PexRD2 interacts with host MAPKKK ε to suppress plant immune signaling. Plant Cell. 2014 Mar;26(3):1345-59. PMID:24632534 doi:10.1105/tpc.113.120055
- ↑ Franco-Orozco B, Berepiki A, Ruiz O, Gamble L, Griffe LL, Wang S, Birch PRJ, Kanyuka K, Avrova A. A new proteinaceous pathogen-associated molecular pattern (PAMP) identified in Ascomycete fungi induces cell death in Solanaceae. New Phytol. 2017 Jun;214(4):1657-1672. PMID:28386988 doi:10.1111/nph.14542
- ↑ Wang S, McLellan H, Bukharova T, He Q, Murphy F, Shi J, Sun S, van Weymers P, Ren Y, Thilliez G, Wang H, Chen X, Engelhardt S, Vleeshouwers V, Gilroy EM, Whisson SC, Hein I, Wang X, Tian Z, Birch PRJ, Boevink PC. Phytophthora infestans RXLR effectors act in concert at diverse subcellular locations to enhance host colonization. J Exp Bot. 2019 Jan 1;70(1):343-356. PMID:30329083 doi:10.1093/jxb/ery360
- ↑ Boutemy LS, King SR, Win J, Hughes RK, Clarke TA, Blumenschein TM, Kamoun S, Banfield MJ. Structures of Phytophthora RXLR Effector Proteins: A CONSERVED BUT ADAPTABLE FOLD UNDERPINS FUNCTIONAL DIVERSITY. J Biol Chem. 2011 Oct 14;286(41):35834-42. Epub 2011 Aug 3. PMID:21813644 doi:10.1074/jbc.M111.262303
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