Author:
Mudge Anna J.,Mehdi Saher,Michaels Will,Orosa-Puente Beatriz,Shen Weiran,Sadanandom Ari,Hetherington Flora M.,Hoppen Claudia,Uzun Buket,Groth Georg,Topping Jennifer F.,Robinson Nigel J.,Lindsey Keith
Abstract
AbstractEthylene 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 signalling. As for other vesicular cupro-proteins, the final step of Cu(I) maturation at the ER is undefined. We previously discovered that mutants in theArabidopsisgenePOLARIS(PLS), encoding a 36 amino acid peptide, exhibit constitutive ethylene signalling responses. Here we report a 1:2 thiol-dependent Cu(I):PLS2complex, with an affinity of 3.79 (±1.5) x1019M-2. We demonstrate PLS interactions with the transmembrane domain of receptor protein ETR1, the Cu(I) chaperones ATX1 and CCH, and Cu(I)-transporting P1B-type ATPase RAN1 at the ER. Formation of Cu(I)-dependent PLS- cuproprotein adducts at the ER provides a mechanism to modulate the metalation of ETR1, thereby regulating its activity and representing a novel mechanism for plant hormone receptor regulation.One Sentence SummaryThe POLARIS peptide ofArabidopsisregulates activity of the ethylene hormone receptor by controlling Cu(I) availability.
Publisher
Cold Spring Harbor Laboratory