A remorin protein from tobacco is targeted by the Pseudomonas type III effector protein HopZ1a: evidence for a novel virulence mechanism?
P. ALBERS (1), S. Üstün (1), C. Schroeder (2), K. Witzel (1), F. Börnke (1) (1) Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), Germany; (2) Institute for Biochemistry and Biology, University of Potsdam, Germany

HopZ1a, a type-3-secreted effector of P. syringae pv. syringae, is an acetyltransferase that was shown to disrupt vesicle transport during innate immunity by acetylating tubulin. To uncover new HopZ1a targets we initiated a yeast-two-hybrid (Y2H) screen and identified a remorin protein as interactor of HopZ1a in tobacco which we named HopZ1a interacting remorin 1 (HIR1). To characterize a potential role of HIR1 in plant immunity, we performed additional Y2H screens and identified the immune kinase PBS1 as well as the E3 ubiquitin ligase SINA4 as putative HIR1-interacting proteins. Using co-IP assays we proved the interaction of HopZ1a and HIR1, as well as PBS1 and HIR1 in vitro. Split-YFP experiments confirmed the interaction in planta with both complexes associating at the plasma membrane. Localization studies using GFP-HIR1 revealed that HIR1 localizes to the plasma membrane and shifts into dot like structures 30 minutes after flg22 treatment, resembling lipid rafts. Preliminary results indicate that overexpression of HIR1 leads to increased basal PTI marker gene expression, and induced ROS production after a flg22 stimulus. Using in vitro kinase assays we confirmed that HIR1 is a direct phosphorylation target of PBS1, and preliminary MS-MS data indicate that HIR1 is phosphorylated by PBS1 at S64. In summary, our findings support the hypothesis that HIR1 might act in a complex together with PBS1 during PTI and hence is targeted by HopZ1a to manipulate immune signaling.

Abstract Number: P9-235
Session Type: Poster