POLARIS is a copper-binding peptide required for ethylene signalling control in Arabidopsis

Le résumé fourni par la source

ABSTRACT Ethylene signalling represents one of the classic hormonal pathways in plants, with diverse roles in development and stress responses. The dimeric ethylene receptor localizes to the endoplasmic reticulum (ER) and contains Cu(I) ions essential for ethylene binding and signal transduction. The final steps of Cu(I) incorporation into the ethylene receptor, and its link with receptor conformation are ill-defined. We previously discovered that mutants in the Arabidopsis gene POLARIS ( PLS ), encoding a 36 amino acid peptide, exhibit enhanced ethylene signalling responses, suggestive of reduced receptor activity. Here we report PLS binds copper as a 1:2 thiol-dependent Cu(I):PLS 2 complex, with an affinity of 3.79 (±1.5) x10 19 M -2 . We demonstrate that PLS localizes to endomembranes and interacts with the transmembrane domain of receptor protein ETR1, the Cu(I) chaperones ATX1 and CCH, and Cu(I)-transporting P 1B -type ATPase RAN1. PLS transcription is up-regulated by auxin and down-regulated by ethylene, and so PLS-cuproprotein interactions provide mechanisms to modulate the activity of ETR1 to regulate ethylene responses in high auxin tissues.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.