Subcellular Localization and In Vivo Interactions of the Arabidopsis thaliana Ethylene Receptor Family Members

Abstract

The gaseous phytohormone ethylene regulates many developmental processes and responses to environmental conditions in higher plants. In Arabidopsis thaliana, ethylene perception and initiation of signaling are mediated by a family of five receptors which are related to prokaryotic two-component sensor histidine kinases. The transient expression of fluorescence-tagged receptors in tobacco (Nicotiana benthamiana) epidermal leaf cells demonstrated that all ethylene receptors are targeted to the ER endomembrane network and do not localize to the plasmalemma. In support of in planta overlay studies, the ethylene receptors form homomeric and heteromeric protein complexes at the ER in living plant cells, as shown by membrane recruitment assays. A comparable in vivo interaction pattern was found in the yeast mating-based split-ubiquitin system. The overlapping but distinct expression pattern of the ethylene receptor genes suggests a differential composition of the ethylene receptor complexes in different plant tissues. Our findings may have crucial functional implications on the ethylene receptor-mediated efficiency of hormone perception, induction of signaling, signal attenuation and output.

The Copper Transporter RAN1 Is Essential for Biogenesis of Ethylene Receptors in Arabidopsis

“…However, the subcellular localization of ETR1 and RAN1 when expressed in yeast remains to be determined. In Arabidopsis, ETR1 is an integral membrane protein located primarily in the membranes of the endoplasmic reticulum (45)(46)(47)(48)(49)(50)(51)(52). Although the subcellular location of RAN1 in Arabidopsis is unknown, our results suggest that it is co-localized in the same subcellular compartment with the receptors at some point during the biogenesis of the receptors in plants.…”

A Combinatorial Interplay Among the 1-Aminocyclopropane-1-Carboxylate Isoforms Regulates Ethylene Biosynthesis inArabidopsis thaliana

“…Very little is known about its biochemical diversity and expression patterns during plant growth. Finally, ethylene is sensed by five different receptors that have the capacity to heterodimerize (Grefen et al 2008) and form 5 homo-and 15 heterodimeric isoforms. The combinatorial interplay among the receptor isoforms in a spatial and temporal manner coupled with potential differences in their affinity for ethylene in vivo may provide the molecular basis for celland tissue-specific ethylene responses (Hall et al 2007;Stepanova et al 2008;Tao et al 2008).…”

Ethylene Regulates Levels of Ethylene Receptor/CTR1 Signaling Complexes in Arabidopsis thaliana

“…The transmembrane domains contain the ethylene-binding site (9 -11), and also serve in localization of the receptor to the endoplasmic reticulum (ER) 4 and possibly to the Golgi apparatus (12)(13)(14)(15). The GAF domain has been implicated in protein-protein interactions among the receptors and may help mediate the formation of higher order receptor clusters (15)(16)(17). The signal output domains of the receptors are related to two-component signaling elements, with all five receptors containing histidine kinaselike domains and all except ERS1 and ERS2 also containing receiver domains.…”