AvrRpm1 Functions as an ADP-Ribosyl Transferase to Modify NOI Domain-Containing Proteins, Including Arabidopsis and Soybean RPM1-Interacting Protein4

• Published in: The Plant cell 2019-11, Vol.31 (11), p.2664
• Main Authors: Redditt, Thomas J, Chung, Eui-Hwan, Karimi, Hana Zand, Rodibaugh, Natalie, Zhang, Yixiang, Trinidad, Jonathan C, Kim, Jin Hee, Zhou, Qian, Shen, Mingzhe, Dangl, Jeffery L, Mackey, David, Innes, Roger W
• Format: Article
• Language: English
• Subjects: ADP Ribose Transferases - metabolism; Arabidopsis; Arabidopsis Proteins - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Glycine max; Intracellular Signaling Peptides and Proteins - metabolism; Mutagenesis, Site-Directed; Mutation; Nicotiana - genetics; Phosphorylation; Plants, Genetically Modified; Pseudomonas syringae - pathogenicity; Soybean Proteins - metabolism; Virulence
• ISSN: 1532-298X; 1532-298X
• DOI: 10.1105/tpc.19.00020R2

The effector protein AvrRpm1 activates the Arabidopsis ( ) intracellular innate immune receptor protein RESISTANCE TO PSEUDOMONAS MACULICOLA1 (RPM1) via modification of a second Arabidopsis protein, RPM1-INTERACTING PROTEIN4 ( RIN4). Prior work has shown that AvrRpm1 induces phosphorylation of RIN4, but homology modeling indicated that AvrRpm1 may be an ADP-ribosyl transferase. Here, we show that AvrRpm1 induces ADP-ribosylation of RIN4 proteins from both Arabidopsis and soybean ( ) within two highly conserved nitrate-induced (NOI) domains. It also ADP ribosylates at least 10 additional Arabidopsis NOI domain-containing proteins. The ADP-ribosylation activity of AvrRpm1 is required for subsequent phosphorylation on Thr-166 of RIN4, an event that is necessary and sufficient for RPM1 activation. We also show that the C-terminal NOI domain of AtRIN4 interacts with the exocyst subunits EXO70B1, EXO70E1, EXO70E2, and EXO70F1. Mutation of either EXO70B1 or EXO70E2 inhibited secretion of callose induced by the bacterial flagellin-derived peptide flg22. Substitution of RIN4 Thr-166 with Asp enhanced the association of RIN4 with EXO70E2, which we posit inhibits its callose deposition function. Collectively, these data indicate that AvrRpm1 ADP-ribosyl transferase activity contributes to virulence by promoting phosphorylation of RIN4 Thr-166, which inhibits the secretion of defense compounds by promoting the inhibitory association of RIN4 with EXO70 proteins.plantcell;31/11/2664/FX1F1fx1.