Proteomic characterization of plant immune complexes using proximity-based BioID 
M. KHAN (1), D. Desveaux (1), R. Subramaniam (2) (1) University of Toronto, Canada; (2) Agriculture and Agri-Food Canada, Canada

Pathogens employ effectors to target host immunity and promote infections. Plants in turn have evolved nucleotide binding leucine-rich repeat (NLR) proteins to detect effectors and initiate effector-triggered immunity (ETI). NLRs monitor effector “sensors” that can represent a domain of the NLR protein resulting in direct effector recognition, or alternatively sensors can represent autonomous proteins that provide indirect recognition. The Pseudomonas syringae type III effector HopZ1a is an acetyltransferase that targets the Arabidopsis effector sensor ZED1.  Acetylation of ZED1 by HopZ1a activates the NLR protein ZAR1, resulting in ETI. Although we know that ZED1 and ZAR1 form a HopZ1a recognition complex, we know very little about additional proteins in this complex or their downstream signaling components. We aim to advance this knowledge by applying proximity dependent biotin identification (BioID) to characterize the ZAR1 immune complex. We have produced functional transgenic Arabidopsis lines of the effector HopZ1a, the sensor ZED1 and the NLR ZAR1, all fused to the promiscuous biotinylating protein (BirA*). We have expressed these proteins and demonstrated promiscuous biotinylation of proteins in planta. We will present our latest efforts to optimize in planta BioID and identify biotinylated proteins by mass spectrometry. This approach will allow us to build a proximity-based ZAR1 network to identify additional components of this immune complex that contribute to ETI. 

Abstract Number: P18-677
Session Type: Poster