2xcm is a 6 chain structure with sequence from Arath and Barley. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
[RAR1_ARATH] Required specifically for plant innate immunity. Is essential for resistance conferred by multiple R genes recognizing different bacterial and oomycete pathogen isolates like avirulent P.syringae or H.parasitica (downy mildew). Contributes additively with SGT1B to RPP5-dependent resistance. Functions as positive regulator of RPS5 accumulation by assisting its stabilization. May function as co-chaperone of HSP90-2 to positively regulate the steady-state accumulation of RPM1 and protect it from SGT1-mediated degradation. Acts as negative regulator of pathogen-associated molecular pattern (PAMP)-triggered immunity.[1][2][3][4][5][6][7][8] [SGT1A_ARATH] Functions in R gene-mediated resistance, but participates in a lower extent than SGT1B to RPP5-mediated resistance. Not required for RPM1, RPS2, RPS4 and RPS5-mediated resistance. Probably required for SCF-mediated ubiquitination, by coupling HSP90 to SCF complex for ubiquitination of HSP90 client proteins.[9]
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 PubMed
Hsp90-mediated function of NLR receptors in plant and animal innate immunity depends on the cochaperone Sgt1 and, at least in plants, on a cysteine- and histidine-rich domains (CHORD)-containing protein Rar1. Functionally, CHORD domains are associated with CS domains, either within the same protein, as in the mammalian melusin and Chp1, or in separate but interacting proteins, as in the plant Rar1 and Sgt1. Both CHORD and CS domains are independently capable of interacting with the molecular chaperone Hsp90 and can coexist in complexes with Hsp90. We have now determined the structure of an Hsp90-CS-CHORD ternary complex, providing a framework for understanding the dynamic nature of Hsp90-Rar1-Sgt1 complexes. Mutational and biochemical analyses define the architecture of the ternary complex that recruits nucleotide-binding leucine-rich repeat receptors (NLRs) by manipulating the structural elements to control the ATPase-dependent conformational cycle of the chaperone.
Structural basis for assembly of Hsp90-Sgt1-CHORD protein complexes: implications for chaperoning of NLR innate immunity receptors.,Zhang M, Kadota Y, Prodromou C, Shirasu K, Pearl LH Mol Cell. 2010 Jul 30;39(2):269-81. PMID:20670895[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑Austin MJ, Muskett P, Kahn K, Feys BJ, Jones JD, Parker JE. Regulatory role of SGT1 in early R gene-mediated plant defenses. Science. 2002 Mar 15;295(5562):2077-80. Epub 2002 Feb 14. PMID:11847308 doi:https://dx.doi.org/10.1126/science.1067747
↑Muskett PR, Kahn K, Austin MJ, Moisan LJ, Sadanandom A, Shirasu K, Jones JD, Parker JE. Arabidopsis RAR1 exerts rate-limiting control of R gene-mediated defenses against multiple pathogens. Plant Cell. 2002 May;14(5):979-92. PMID:12034891
↑Tornero P, Merritt P, Sadanandom A, Shirasu K, Innes RW, Dangl JL. RAR1 and NDR1 contribute quantitatively to disease resistance in Arabidopsis, and their relative contributions are dependent on the R gene assayed. Plant Cell. 2002 May;14(5):1005-15. PMID:12034893
↑Hubert DA, Tornero P, Belkhadir Y, Krishna P, Takahashi A, Shirasu K, Dangl JL. Cytosolic HSP90 associates with and modulates the Arabidopsis RPM1 disease resistance protein. EMBO J. 2003 Nov 3;22(21):5679-89. PMID:14592967 doi:https://dx.doi.org/10.1093/emboj/cdg547
↑Holt BF 3rd, Belkhadir Y, Dangl JL. Antagonistic control of disease resistance protein stability in the plant immune system. Science. 2005 Aug 5;309(5736):929-32. Epub 2005 Jun 23. PMID:15976272 doi:https://dx.doi.org/10.1126/science.1109977
↑Shang Y, Li X, Cui H, He P, Thilmony R, Chintamanani S, Zwiesler-Vollick J, Gopalan S, Tang X, Zhou JM. RAR1, a central player in plant immunity, is targeted by Pseudomonas syringae effector AvrB. Proc Natl Acad Sci U S A. 2006 Dec 12;103(50):19200-5. Epub 2006 Dec 5. PMID:17148606 doi:https://dx.doi.org/10.1073/pnas.0607279103
↑Kawamura Y, Takenaka S, Hase S, Kubota M, Ichinose Y, Kanayama Y, Nakaho K, Klessig DF, Takahashi H. Enhanced defense responses in Arabidopsis induced by the cell wall protein fractions from Pythium oligandrum require SGT1, RAR1, NPR1 and JAR1. Plant Cell Physiol. 2009 May;50(5):924-34. doi: 10.1093/pcp/pcp044. Epub 2009 Mar, 20. PMID:19304739 doi:https://dx.doi.org/10.1093/pcp/pcp044
↑Hubert DA, He Y, McNulty BC, Tornero P, Dangl JL. Specific Arabidopsis HSP90.2 alleles recapitulate RAR1 cochaperone function in plant NB-LRR disease resistance protein regulation. Proc Natl Acad Sci U S A. 2009 Jun 16;106(24):9556-63. doi:, 10.1073/pnas.0904877106. Epub 2009 Jun 1. PMID:19487680 doi:https://dx.doi.org/10.1073/pnas.0904877106
↑Azevedo C, Betsuyaku S, Peart J, Takahashi A, Noel L, Sadanandom A, Casais C, Parker J, Shirasu K. Role of SGT1 in resistance protein accumulation in plant immunity. EMBO J. 2006 May 3;25(9):2007-16. Epub 2006 Apr 13. PMID:16619029 doi:https://dx.doi.org/10.1038/sj.emboj.7601084
↑Zhang M, Kadota Y, Prodromou C, Shirasu K, Pearl LH. Structural basis for assembly of Hsp90-Sgt1-CHORD protein complexes: implications for chaperoning of NLR innate immunity receptors. Mol Cell. 2010 Jul 30;39(2):269-81. PMID:20670895 doi:10.1016/j.molcel.2010.05.010
