Bacterial effector modulation of host E3 ligase activity suppresses PAMP-triggered immunity in rice

• Published in: Nature communications 2014-11, Vol.5 (1), p.5430-5430, Article 5430
• Main Authors: Ishikawa, Kazuya, Yamaguchi, Koji, Sakamoto, Kazuaki, Yoshimura, Satomi, Inoue, Kento, Tsuge, Seiji, Kojima, Chojiro, Kawasaki, Tsutomu
• Format: Article
• Language: English
• Subjects: 38/89; 631/449/1659; 631/449/2169; 82/111; 82/29; 82/83; 96/95; Bacterial Proteins - genetics; Bacterial Proteins - physiology; Gene Silencing - physiology; Host-Pathogen Interactions - immunology; Host-Pathogen Interactions - physiology; Humanities and Social Sciences; multidisciplinary; Oryza - genetics; Oryza - immunology; Oryza - microbiology; Pathogen-Associated Molecular Pattern Molecules - metabolism; Peptidoglycan - metabolism; Plant Diseases - immunology; Plant Diseases - microbiology; Plant Immunity - physiology; Plant Proteins - genetics; Plant Proteins - physiology; Science; Science (multidisciplinary); Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - physiology; Xanthomonas - pathogenicity; Xanthomonas - physiology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms6430

Pathogen effector proteins are delivered to host cells to suppress plant immunity. However, the mechanisms by which effector proteins function are largely unknown. Here we show that expression of XopP Xoo , an effector of rice pathogen Xanthomonas oryzae pv. oryzae , in rice strongly suppresses peptidoglycan (PGN)- and chitin-triggered immunity and resistance to X. oryzae . XopP Xoo targets OsPUB44, a rice ubiquitin E3 ligase with a unique U-box domain. We find that XopP Xoo directly interacts with the OsPUB44 U-box domain and inhibits ligase activity. Two amino-acid residues specific for the OsPUB44 U-box domain are identified, which are responsible for the interaction with XopP Xoo . Silencing of OsPUB44 suppresses PGN- and chitin-triggered immunity and X. oryzae resistance, indicating that OsPUB44 positively regulates immune responses. Thus, it is likely that XopP Xoo suppresses immune responses by directly interacting with and inhibiting a positive regulator of plant immunity. The mechanisms by which pathogen effector proteins target host defence responses remain poorly understood. Here, Ishikawa et al. show that XopP Xoo , a rice pathogen effector, suppresses host plant immunity by inhibiting the activity of an E3 ubiquitin ligase.