A peptide that regulates metalation and function of theArabidopsisethylene receptor

Abstract

The vital plant ethylene receptor (ETR1) contains an essential Cu(I) ion, and as for other vesicular cupro-proteins, the final step of Cu(I) maturation at the endoplasmic reticulum (ER) is undefined. We previously discovered that mutants in the Arabidopsis gene POLARIS (PLS), encoding a 36 amino acid peptide, exhibit constitutive ethylene signalling responses. Here we report a 1:2 thiol-dependent Cu(I):PLS2 complex, with an affinity of 3.79 (± 1.5) x1019 M-2. We demonstrate interactions with the transmembrane domain of 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 distinct mechanism for plant hormone receptor regulation.

A predictive model for ethylene-mediated auxin and cytokinin patterning in the Arabidopsis root

“…The modeled trends were in general agreement with experimental observations, although modeled auxin concentration was markedly lower in the pls etr1 double mutant than in its experimental counterpart. PLS is a protein that interacts with ethylene receptors ( Casson et al., 2002 ; Chilley et al., 2006 ; Liu et al., 2010 ; Mudge et al., 2023 ), and manipulation of PLS activity affects ethylene signaling ( Chilley et al., 2006 ; Liu et al., 2010 ). Therefore, when both auxin and cytokinin patterning are fitted to experimental observations according to the proposed mechanism ( Figure 1 ), the effects of genetic manipulation of ethylene signaling on average auxin concentration in the root can also be predicted.…”