The plasma membrane is at the interface of plant-pathogen interactions and thus many bacterial type-III effector proteins (T3Es) target membrane-associated processes to interfere with immunity. The Pseudomonas syringae T3E HopZ1a is a host cell plasma membrane (PM)-localized effector protein that has several immunity associated host targets but also activates effector triggered immunity (ETI) in resistant backgrounds. Although HopZ1a has been shown to interfere with early defense signaling at the PM, no dedicated plasma membrane-associated HopZ1a target protein has been identified until now. We show here, that HopZ1a interacts with the PM-associated remorin protein NbREM4 from Nicotiana benthamiana in several independent assays. NbREM4 re-localizes to membrane sub-nanodomains after treatment with the bacterial elicitor flg22 and transient overexpression of NbREM4 in N. benthamiana induces the expression of a subset of defense related genes. We can further show that NbREM4 interacts with the immune-related receptor-like cytoplasmic kinase PBS1 and is phosphorylated by PBS1 on several residues in vitro. Thus, we conclude that NbREM4 is associated with early defense signaling at the PM. The possible relevance of the HopZ1a/NbREM4 interaction for HopZ1a virulence and avirulence functions is discussed.
This journey started in 2012 when I was a PhD student in the lab of Frederik Börnke. Philip Albers continued to work on this project during his PhD thesis and it is great to see this paper from the Börnke and Üstün Labs being published in Molecular Plant-Microbe Interaction. Congrats to everyone involved in this story!
Suayib Üstün, thanks so much for the post.Much thanks again. Really Cool.