Investigating the role of bacterial effector phosphorylation and 14-3-3 binding
L. LEI (1) (1) University of California Davis, U.S.A.

A critical component controlling bacterial virulence is the delivery of pathogen effectors into plant cells during infection. Effectors can suppress immune responses by directly targeting PAMP receptors or by interfering with downstream signaling processes. 14-3-3 proteins define a eukaryotic-specific conserved protein family with a primary role in signal transduction. We have previously demonstrated that the conserved bacterial effector HopQ1 is phosphorylated in tomato and associates with tomato 14-3-3 proteins to promote pathogen virulence. In order to determine the extent of potential effector 14-3-3 binding, a plant-specific 14-3-3 binding prediction pipeline was developed. The effector repertoires for pathogenic Pseudomonas, Xanthomonas, and Ralstonia solanacearum strains were significantly enriched in 14-3-3 binding sites compared to background genomes. The Xanthomonas TALE effector family possesses two highly conserved 14-3-3 binding sites. The phosphorylation of one Xanthomonas TALE effector and its ability to associate with tomato 14-3-3 proteins was confirmed. Mutation of two 14-3-3 binding sites in this TALE did not affect its subcellular localization but reduced transcriptional activity.  Data will also be presented on the importance of effector phosphorylation and 14-3-3 binding for additional effector families. Collectively, these data highlight the importance of host-mediated effector phosphorylation.

Abstract Number: P3-73
Session Type: Poster