Role of SCF Ubiquitin-Ligase and the COP9 Signalosome in the N Gene-Mediated Resistance Response to Tobacco mosaic virus

• Published in: The Plant cell Vol. 14; no. 7; pp. 1483 - 1496
• Main Authors: Liu, Yule, Schiff, Michael, Serino, Giovanna, Deng, Xing-Wang, Dinesh-Kumar, S. P.
• Format: Journal Article
• Language: English
• Published: England American Society of Plant Biologists 01.07.2002
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Antibodies; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biodegradation; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Complementary DNA; COP9 Signalosome Complex; Genes, Viral; Immunity, Innate - genetics; Leaves; Molecular Sequence Data; Multiprotein Complexes; Nicotiana - genetics; Nicotiana - metabolism; Nicotiana - virology; Peptide Hydrolases; Peptide Synthases - genetics; Peptide Synthases - metabolism; Plant cells; Plant Diseases - genetics; Plant Diseases - virology; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Polymerase chain reaction; Proteins; Proteins - genetics; Proteins - metabolism; RNA; Sequence Alignment; Sequence Homology, Amino Acid; Signal Transduction; SKP Cullin F-Box Protein Ligases; Tobacco; Tobacco Mosaic Virus - growth & development; Two-Hybrid System Techniques; Ubiquitin - metabolism; Ubiquitins; Yeasts
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.002493

The tobacco N gene confers resistance to Tobacco mosaic virus (TMV) and encodes a toll-interleukin-1 receptor/nucleotide binding/Leu-rich repeat class protein. Recent evidence indicates that the Nicotiana benthamiana Rar1 gene (NbRar1), which encodes a protein with a zinc finger motif called CHORD (Cys- and His-rich domain), is required for the function of N. To investigate the role of NbRar1 in plant defense, we identified its interaction partners. We show that the NbRar1 protein interacts with NbSGT1, a highly conserved component of the SCF (Skp1/Cullin/F-box protein)-type E3 ubiquitin ligase complex involved in protein degradation. In addition, we show that NbSGT1 interacts with NbSKP1. Suppression of NbSGT1 and NbSKP1 shows that these genes play an important role in the N-mediated resistance response to TMV. Both NbRar1 and NbSGT1 associate with the COP9 signalosome, another multiprotein complex involved in protein degradation via the ubiquitin-proteasome pathway. Silencing of the NbCOP9 signalosome also compromises N-mediated resistance to TMV. Our results reveal new roles for SCF and the COP9 signalosome in plant defense signaling.