6WPG

Structural Basis of Salicylic Acid Perception by Arabidopsis NPR Proteins

Summary for 6WPG

• Entry DOI: 10.2210/pdb6wpg/pdb
• Descriptor: Regulatory protein NPR4, 2-HYDROXYBENZOIC ACID (3 entities in total)
• Functional Keywords: npr4, arabidopsis, salicylic acid, sa, receptor, plant immunity, plant protein
• Biological source: Arabidopsis thaliana (Mouse-ear cress)
• Total number of polymer chains: 2
• Total formula weight: 41329.05

Authors

Wang, W.,Withers, J.,Li, H.,Zwack, P.J.,Rusnac, D.V.,Shi, H.,Liu, L.,Yan, S.,Hinds, T.R.,Guttman, M.,Dong, X.,Zheng, N. (deposition date: 2020-04-27, release date: 2020-08-12, Last modification date: 2024-03-06)

Primary citation

Wang, W.,Withers, J.,Li, H.,Zwack, P.J.,Rusnac, D.V.,Shi, H.,Liu, L.,Yan, S.,Hinds, T.R.,Guttman, M.,Dong, X.,Zheng, N.
Structural basis of salicylic acid perception by Arabidopsis NPR proteins.
Nature, 586:311-316, 2020

PubMed Abstract: Salicylic acid (SA) is a plant hormone that is critical for resistance to pathogens. The NPR proteins have previously been identified as SA receptors, although how they perceive SA and coordinate hormonal signalling remain unknown. Here we report the mapping of the SA-binding core of Arabidopsis thaliana NPR4 and its ligand-bound crystal structure. The SA-binding core domain of NPR4 refolded with SA adopts an α-helical fold that completely buries SA in its hydrophobic core. The lack of a ligand-entry pathway suggests that SA binding involves a major conformational remodelling of the SA-binding core of NPR4, which we validated using hydrogen-deuterium-exchange mass spectrometry analysis of the full-length protein and through SA-induced disruption of interactions between NPR1 and NPR4. We show that, despite the two proteins sharing nearly identical hormone-binding residues, NPR1 displays minimal SA-binding activity compared to NPR4. We further identify two surface residues of the SA-binding core, the mutation of which can alter the SA-binding ability of NPR4 and its interaction with NPR1. We also demonstrate that expressing a variant of NPR4 that is hypersensitive to SA could enhance SA-mediated basal immunity without compromising effector-triggered immunity, because the ability of this variant to re-associate with NPR1 at high levels of SA remains intact. By revealing the structural mechanisms of SA perception by NPR proteins, our work paves the way for future investigation of the specific roles of these proteins in SA signalling and their potential for engineering plant immunity.

PubMed: 32788727
DOI: 10.1038/s41586-020-2596-y

Experimental method

X-RAY DIFFRACTION (2.283 Å)