A Remorin from Nicotiana benthamiana Interacts with the Pseudomonas Type-III Effector Protein HopZ1a and is Phosphorylated by the Immune-Related Kinase PBS1

Abstract

The plasma membrane (PM) is at the interface of plant–pathogen interactions and, thus, many bacterial type-III effector (T3E) proteins target membrane-associated processes to interfere with immunity. The Pseudomonas syringae T3E HopZ1a is a host cell PM-localized effector protein that has several immunity-associated host targets but also activates effector-triggered immunity in resistant backgrounds. Although HopZ1a has been shown to interfere with early defense signaling at the PM, no dedicated PM-associated HopZ1a target protein has been identified until now. Here, we show that HopZ1a interacts with the PM-associated remorin protein NbREM4 from Nicotiana benthamiana in several independent assays. NbREM4 relocalizes to membrane 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 avrPphB-susceptible 1 (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. [Formula: see text]Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Endomembrane-Targeting Plasmodiophora brassicae Effectors Modulate PAMP Triggered Immune Responses in Plants

“…flg22 interacts with Flagellin Sensing-2 (FLS-2), associated with lipid rafts and triggers the endocytosis of the FLS2-flg22 complex into endosomes that are sorted at the trans-Golgi network and targeted for degradation, probably in the vacuole ( Jelenska et al, 2017 ). A similar pattern of fluorescence distribution, due to membrane raft reorganization, has been observed for GFP- Nb REM4 and FLS2, after flg22 treatment ( Keinath et al, 2010 ; Albers et al, 2019 ). An increase in B. rapa FLS2 (BraA09g021780.3C) transcript levels has been observed after infection with a virulent strain (SCCD-52) of P. brassicae ( Fu et al, 2019 ).…”

“…Therefore, we investigated the dynamics of Δ sp Pb PE13GFP localization upon flg22 perception in N. benthamiana . Treatment with flg22, a peptide derived from the flagellin N-terminus of Pseudomonas aeruginosa , triggered the association of Nb REM4 and fluorescence distribution due to membrane raft re-organization and compartmentalization within PM lipid rafts ( Keinath et al, 2010 ; Albers et al, 2019 ). With a concentrated localization of Δ sp Pb PE13GFP to PM lipid rafts, we wanted to determine if Δ sp Pb PE13GFP showed a similar localization pattern to Nb REM4 upon biotic stress.…”

“…The lipid raft marker Remorin has been detected in association with PD, where they are thought to modulate the PD size exclusion limit (SEL) and regulate pathogen movement across the raft enriched PM ( Raffaele et al, 2009 ; Perraki et al, 2014 ; Gronnier et al, 2017 ; Sasaki et al, 2018 ). In N. benthamiana , the Pseudomonas syringae effector HopZ1a, which interferes with early immune signaling at the PM in plants, interacts with the lipid raft localized protein REMORIN4 ( Nb REM4) ( Albers et al, 2019 ). Similarly in Arabidopsis, the P. syringae effector HopF2, which suppresses the PTI response by interacting with the BAK1 receptor at the PM, is also associated with the remorins At REM1.2 and At REM1.3 ( Zhou et al, 2014 ; Khan et al, 2018b ).…”

“…The importance of nanodomains within the PM in early defense signaling and cell to cell communication has been well-documented in plant cells ( Raffaele et al, 2009 ; Perraki et al, 2014 ; Gronnier et al, 2017 ; Sasaki et al, 2018 ; Albers et al, 2019 ). However, while PM lipid rafts are important in the activation of the human immune system, several intracellular pathogenic bacteria can hijack these rafts to facilitate entry into the host cell or modulate defense signaling for survival inside the cell ( Mañes et al, 2003 ; Hartlova et al, 2010 ).…”

An Ancestry Perspective of the Evolution of PBS1 Proteins in Plants

“…Indeed, PBS1 and PBS1-like proteins, such as BIK1 and PBL1, play important roles in signaling from the cell surface immune receptors, but may not play an essential function in PTI signaling, becoming a decoy by mimicking true virulence targets to trigger ETI [19,27]. According to previous reports, PBS1 has a kinase activity (autophosphorylation) that activates HR mediated by RPS5 in Arabidopsis, but also PBS1 from N. benthamiana, and can phosphorylate NbREM4 (remorin protein) in vitro, allowing the interaction with HopZ1a (host cell plasma membrane localized effector protein) triggering the ZAR1-dependent HR in N. benthamiana [28,29]. Arabidopsis PBS1 is grouped within a so-called universal stress response transcriptome because it includes genes that are induced by diverse conditions, such as osmotic shock, cold, salinity, wounding, and biotic stress, indicating that PBS1 responds to both abiotic and biotic stress [30].…”