Structural dynamics of the plant hormone receptor ETR1 in a native-like membrane environment.

Ethylene (C₂H₄) regulates plant processes, such as germination, fruit ripening, and stress responses, impacting nutrition and food quality. The membrane-bound receptor ETR1 from Arabidopsis thaliana is a model for ethylene signaling, but both full-length and the soluble cytoplasmic domain have resisted crystallization. We present high-resolution NMR spectra of full-length ETR1 reconstituted in lipid nanodiscs, overcoming limitations and enhancing sample uniformity. ETR1 shows high internal dynamics with regions decoupled from the transmembrane domain, possibly explaining past crystallization failures and reflecting functional flexibility. Introduction of Cu(I), an essential cofactor for ethylene binding, stiffened receptor dynamics, suggesting a stabilizing role in signal transmission. This work demonstrates nanodisc-based strategies as powerful tools for resolving membrane protein structures in plant signaling.