Start me up: Revision of evidences that AtGRP3 acts as a potential switch for AtWAK1

Abstract

AtGRP3 is a glycine-rich protein from Arabidopsis thaliana shown to interact with the extracellular domain of the receptor-like kinase (RLK) AtWAK1. Based on previous functional data for AtWAK1, a model was proposed that AtGRP3 when bound to this RLK would negatively regulate its kinase activity, inhibiting cell expansion. Here, we review recent functional studies on AtGRP3 that corroborate this model and suggest that AtGRP3/AtWAK1 complex regulates also defense signaling pathways. On the other hand, we show new data on AtGRP3-overexpressing plants indicating that its role in aluminum signaling pathways, as previously observed for elicitor signaling, seems to be more complex than a simple negative regulator.

A wall with integrity: surveillance and maintenance of the plant cell wall under stress

“…In addition to pectins, GRP3, a wall structural protein, is also a ligand for WAK1 (Park et al ., ). GRP3 negatively regulates cell expansion and OG‐triggered defense response, likely through WAK1 (Gramegna et al ., ; Mangeon et al ., , ). These data point to a functional link between WAKs and the cell wall, but evidence demonstrating that WAKs are CWI sensors is still lacking.…”

Signals and Their Perception for Remodelling, Adjustment and Repair of the Plant Cell Wall

“…The WAK1/GRP3 complex associates with the KINASE-ASSOCIATED PROTEIN PHOSPHATASE (KAPP) [ 164 , 164 ], and the trimeric complex negatively affects defense responses induced by OGs [ 164 ]. GRP3 and WAK1 are also involved in cell elongation, root development and aluminum resistance (reviewed in [ 165 , 166 , 167 , 168 ]). Apparently, the activated WAKs induce a quite diverse set of cellular responses, which also depend on WAK-interaction partners.…”

LsGRP1, a class II glycine‐rich protein of Lilium, confers plant resistance via mediating innate immune activation and inducing fungal programmed cell death

“…However, the other AtGRP3 interactor AtWAK1, a cell wall-associated receptor-like kinase serving as an oligogalacturonide receptor, acts conversely except that it is unresponsive to flg22 (Park et al, 2001;Yang et al, 2003;Gramegna et al, 2016). In addition, AtGRP3/AtWAK1 interaction is involved in root size determination and aluminium response (Park et al, 2001;Mangeon et al, 2016Mangeon et al, , 2017. However, AtGRP3 enables defence induction of callose deposition and ROS accumulation through directly interacting with the bacterial elicitor HrpE, which presents in type III protein secretion pilus of Xanthomonas citri subsp.…”