The role of NOI-domain containing proteins in plant immune signaling

Abstract

Here we present an overview of our existing knowledge on the function of RIN4 as a regulator of plant defense and as a guardee of multiple plant R-proteins. Domain analysis of RIN4 reveals two NOI domains. The NOI domain was originally identified in a screen for nitrate induced genes. The domain is comprised of approximately 30 amino acids and contains 2 conserved motifs (PXFGXW and Y/FTXXF). The NOI gene family contains members exclusively from the plant lineage as far back as moss. In addition to the conserved NOI domain, members within the family also contain conserved C-terminal cysteine residue(s) which are sites for acylation and membrane tethering. Other than these two characteristic features, the sequence of the family of NOI-containing proteins is diverse and, with the exception of RIN4, their functions are not known. Recently published interactome data showing interactions between RIN4 and components of the exocyst complex prompt us to raise the hypothesis that RIN4 might be involved in defense associated vesicle trafficking.

Phosphorylation of the Plant Immune Regulator RPM1-INTERACTING PROTEIN4 Enhances Plant Plasma Membrane H+-ATPase Activity and Inhibits Flagellin-Triggered Immune Responses in Arabidopsis

“…There are 15 Arabidopsis proteins possessing homology to RIN4 and all share a common nitrate induced domain (NOI, Pfam: PF05627) (Afzal et al, 2013). The NOI domain is also present across land plants (Afzal et al, 2013). Importantly, NOI domains within RIN4 are targeted by AvrRpt2 for cleavage and AvrB to induce phosphorylation (Chisholm et al, 2005;Chung et al, 2011;Liu et al, 2011).…”

“…Here, we focused on the role of effector-induced RIN4 phosphorylation in susceptible plant genotypes lacking the RPM1 and RPS2 immune receptors. There are 15 Arabidopsis proteins possessing homology to RIN4 and all share a common nitrate induced domain (NOI, Pfam: PF05627) (Afzal et al, 2013). The NOI domain is also present across land plants (Afzal et al, 2013).…”

“…The Thr-21 and Thr-166 residues are conserved between RIN4 proteins present in land plants, but the Ser-160 residue is not (Afzal et al, 2013). Therefore, we focused on the role of Thr-21 and Thr-166 in suppressing PTI.…”

Multiple strategies for pathogen perception by plant immune receptors

“…Therefore, one guardee or decoy can be a target for multiple sequence-unrelated effectors but guarded by only a single or a few NLRs. For instance, the Arabidopsis RPM1 interacting protein 4 (RIN4) guardee protein is targeted by four bacterial effectors and is guarded by two independent NLR proteins (Afzal et al, 2013).…”

Bacterial AvrRpt2-Like Cysteine Proteases Block Activation of the Arabidopsis Mitogen-Activated Protein Kinases, MPK4 and MPK11

“…3A; Kim et al, 2005a;Afzal et al, 2013). All NOIs were cleaved by AvrRpt2 when expressed in protoplasts (Fig.…”