Rice XA21 Binding Protein 3 Is a Ubiquitin Ligase Required for Full Xa21-Mediated Disease Resistance

• Published in: The Plant cell Vol. 18; no. 12; pp. 3635 - 3646
• Main Authors: Wang, Yong-Sheng, Pi, Li-Ya, Chen, Xiuhua, Chakrabarty, Pranjib K, Jiang, Junda, De Leon, Alfred Lopez, Liu, Guo-Zhen, Li, Liangcai, Benny, Ulla, Oard, James, Ronald, Pamela C, Song, Wen-Yuan
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.12.2006
• Subjects: Amino Acid Sequence; Ankyrin Repeat; Disease resistance; Gene Dosage; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Immunity, Innate - genetics; Immunity, Innate - immunology; Molecular Sequence Data; Oryza - enzymology; Oryza - genetics; Oryza sativa; Phosphorylation; Plant Diseases - genetics; Plant Diseases - immunology; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Protein Binding; Protein Structure, Tertiary; Protein-Serine-Threonine Kinases - metabolism; Recombinant Fusion Proteins - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Substrate Specificity; Thermodynamics; Transgenic plants; Ubiquitin - metabolism; Ubiquitin-Protein Ligases - chemistry; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; Xanthomonas oryzae; Yeasts; Yeasts - enzymology
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.106.046730

XA21 is a receptor-like kinase protein in rice (Oryza sativa) that confers gene-for-gene resistance to specific races of the causal agent of bacterial blight disease, Xanthomonas oryzae pv oryzae. We identified XA21 binding protein 3 (XB3), an E3 ubiquitin ligase, as a substrate for the XA21 Ser and Thr kinase. The interaction between XB3 and the kinase domain of XA21 has been shown in yeast and in vitro, and the physical association between XB3 and XA21 in vivo has also been confirmed by coimmunoprecipitation assays. XB3 contains an ankyrin repeat domain and a RING finger motif that is sufficient for its interaction with the kinase domain of XA21 and for its E3 ubiquitin ligase activity, respectively. Transgenic plants with reduced expression of the Xb3 gene are compromised in resistance to the avirulent race of X. oryzae pv oryzae. Furthermore, reduced levels of Xb3 lead to decreased levels of the XA21 protein. These results indicate that Xb3 is necessary for full accumulation of the XA21 protein and for Xa21-mediated resistance.