The RAR1 Interactor SGT1, an Essential Component of R Gene-Triggered Disease Resistance

Plant disease resistance (R) genes trigger innate immune responses upon pathogen attack. RAR1 is an early convergence point in a signaling pathway engaged by multiple R genes. Here, we show that RAR1 interacts with plant orthologs of the yeast protein SGT1, an essential regulator in the cell cycle. Silencing the barley geneSgt1 reveals its role in R gene–triggered,Rar1-dependent disease resistance. SGT1 associates with SKP1 and CUL1, subunits of the SCF (Skp1-Cullin–F-box) ubiquitin ligase complex. Furthermore, the RAR1-SGT1 complex also interacts with two COP9 signalosome components. The interactions among RAR1, SGT1, SCF, and signalosome subunits indicate a link between disease resistance and ubiquitination.

[1]  R. Farràs,et al.  Intron-tagged epitope: a tool for facile detection and purification of proteins expressed in Agrobacterium-transformed plant cells. , 2000, The Plant journal : for cell and molecular biology.

[2]  S. Dinesh-Kumar,et al.  Signaling in plant-microbe interactions. , 1997, Science.

[3]  P. Schulze-Lefert,et al.  A Novel Class of Eukaryotic Zinc-Binding Proteins Is Required for Disease Resistance Signaling in Barley and Development in C. elegans , 1999, Cell.

[4]  M. Estelle,et al.  The Arabidopsis cullin AtCUL1 is modified by the ubiquitin-related protein RUB1. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[5]  C. Schwechheimer,et al.  COP9 signalosome revisited: a novel mediator of protein degradation. , 2001, Trends in cell biology.

[6]  P. Schulze-Lefert,et al.  The MLA6 coiled-coil, NBS-LRR protein confers AvrMla6-dependent resistance specificity to Blumeria graminis f. sp. hordei in barley and wheat. , 2001, The Plant journal : for cell and molecular biology.

[7]  Jonathan D. G. Jones,et al.  Plant pathogens and integrated defence responses to infection , 2001, Nature.

[8]  P. Schulze-Lefert,et al.  Double-stranded RNA interferes with gene function at the single-cell level in cereals , 2000, The Plant Journal.

[9]  C. Schwechheimer,et al.  Interactions of the COP9 Signalosome with the E3 Ubiquitin Ligase SCFTIR1 in Mediating Auxin Response , 2001, Science.

[10]  J. H. Jørgensen,et al.  Effect of three suppressors on the expression of powdery mildew resistance genes in barley. , 1996, Genome.

[11]  P. Schulze-Lefert,et al.  Cell-autonomous complementation of mlo resistance using a biolistic transient expression system , 1999 .

[12]  G. Blatch,et al.  The tetratricopeptide repeat: a structural motif mediating protein-protein interactions. , 1999, BioEssays : news and reviews in molecular, cellular and developmental biology.

[13]  L. Silengo,et al.  Melusin Is a New Muscle-specific Interactor for β1Integrin Cytoplasmic Domain* , 1999, The Journal of Biological Chemistry.

[14]  P. Schulze-Lefert,et al.  Cell-Autonomous Expression of Barley Mla1 Confers Race-Specific Resistance to the Powdery Mildew Fungus via a Rar1-Independent Signaling Pathway , 2001, Plant Cell.

[15]  A. Caudy,et al.  Regulation of Transcriptional Activation Domain Function by Ubiquitin , 2001, Science.

[16]  S. Elledge,et al.  SGT1 encodes an essential component of the yeast kinetochore assembly pathway and a novel subunit of the SCF ubiquitin ligase complex. , 1999, Molecular cell.

[17]  P. Schulze-Lefert,et al.  Regulators of cell death in disease resistance , 2000, Plant Molecular Biology.

[18]  D. Eisenberg,et al.  A combined algorithm for genome-wide prediction of protein function , 1999, Nature.

[19]  C. Pickart,et al.  Ubiquitin enters the new millennium. , 2001, Molecular cell.

[20]  A. Shevchenko,et al.  Promotion of NEDD8-CUL1 Conjugate Cleavage by COP9 Signalosome , 2001, Science.

[21]  Jonathan D. G. Jones,et al.  EDS1, an essential component of R gene-mediated disease resistance in Arabidopsis has homology to eukaryotic lipases. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[22]  P. Repetti,et al.  NDR1, a pathogen-induced component required for Arabidopsis disease resistance. , 1997, Science.

[23]  J. Dangl,et al.  The Arabidopsis thaliana RPM1 disease resistance gene product is a peripheral plasma membrane protein that is degraded coincident with the hypersensitive response. , 1998, Proceedings of the National Academy of Sciences of the United States of America.