Diverse host targets of a conserved Pseudomonas syringae effector form an ARF-GEF-based complex in Arabidopsis
K. NOMURA (1) (1) MSU, U.S.A.

Bacterial type III effector proteins play a critical role in mediating bacterial interactions with plant hosts. We have been characterizing the host targets of Pseudomonas syringae effectors to understand the mechanisms of bacterial pathogenesis in plants. In the past few years, we noticed that an increasing number of bacterial effectors have been reported to target sequence-unrelated host proteins with unknown functional relationships.  The P. syringae pv. tomato effector HopM1 is such an example; it interacts with and/or degrades several HopM1-interacting (MIN) Arabidopsis proteins, including MIN2 (RAD23), MIN7 (ARF-GEF), MIN10 (14-3-3 KAPPA), and MIN13 (ARF-GEF). We purified the MIN7 complex formed in planta and found that it contains MIN7, MIN10, MIN13, as well as a novel tetratricopeptide repeat (TPR) protein named MIT1. Mutational analysis showed that MIT1 is required for pathogen-associated molecular pattern (PAMP)-, effector-, and benzothiadiazole (BTH)-triggered immunity. Furthermore, MIT1 is recruited to the trans-Golgi network (TGN)/early endosome (EE) in a MIN7-dependent manner. Thus, diverse host targets of HopM1 form a novel ARF-GEF-based protein complex required for  P. syringae pathogenesis in Arabidopsis 

Abstract Number: P7-197
Session Type: Poster