9T26

Plant HSL3/NUT receptor in complex with disulfide-stabilized CTNIP4/SCREW2 peptide

Summary for 9T26

• Entry DOI: 10.2210/pdb9t26/pdb
• Descriptor: Kinase family with leucine-rich repeat domain-containing protein, Transmembrane protein, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (5 entities in total)
• Functional Keywords: plasma membrane receptor peptide signaling plant immune signaling, plant protein
• Biological source: Arabidopsis thaliana (thale cress); More
• Total number of polymer chains: 2
• Total formula weight: 71846.42

Authors

Jimenez Sandoval, P.,Santiago, J. (deposition date: 2025-10-22, release date: 2026-09-30)

Primary citation

Jimenez-Sandoval, P.,Johanndrees, O.,Snoeck, S.,Harshith, C.Y.,Omary, M.,Broyart, C.,Rhodes, J.,Bender, K.W.,Zipfel, C.,Santiago, J.
A disulfide bond sculpts the CTNIP4 phytocytokine fold for recognition by the receptor kinase HSL3.
Nat.Plants, 12:1688-1697, 2026

PubMed Abstract: Precise ligand recognition by closely related leucine-rich repeat receptor kinases (LRR-RKs) is essential for plants to coordinate immunity, development and environmental adaptation. Here we show how the LRR-RK HSL3/NUT specifically recognizes the folded, disulfide-stabilized CTNIP4/SCREW2 phytocytokine in Arabidopsis. Quantitative binding assays define a minimal CTNIP4 region required for high-affinity HSL3 interaction and signalling activation. A 2.12-Å crystal structure of the HSL3-CTNIP4 complex reveals a unique C-terminal receptor pocket that accommodates the peptide's cyclic architecture through a combination of hydrophobic and polar contacts, a feature absent in the closely related HAE/HSL LRR-RKs. The cyclic CTNIP4 fold further establishes a largely hydrophobic interface that bridges HSL3 to the SERK co-receptor, forming a distinct activation surface. Together, these structural, biochemical and physiological insights uncover a previously unrecognized mechanism of CTNIP4 peptide perception and HSL3 receptor activation, highlighting how subtle architectural variations enable precise ligand selectivity among highly conserved plant receptor kinases.

PubMed: 42754655
DOI: 10.1038/s41477-026-02380-y

Experimental method

X-RAY DIFFRACTION (2.122 Å)