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Localization of the Raf-like Kinase CTR1 to the Endoplasmic Reticulum of Arabidopsis through Participation in Ethylene Receptor Signaling Complexes

2003; Elsevier BV; Volume: 278; Issue: 36 Linguagem: Inglês

10.1074/jbc.m305548200

1083-351X

Zhiyong Gao, Yi-Feng Chen, Melynda D. Randlett, Xue-Chu Zhao, Jennifer L. Findell, Joseph J. Kieber, G. Eric Schaller,

Plant Stress Responses and Tolerance

The plant hormone ethylene is perceived by a five-member family of receptors related to the bacterial histidine kinases. The Raf-like kinase CTR1 functions downstream of the ethylene receptors as a negative regulator of ethylene signal transduction. CTR1 is shown here to be associated with membranes of the endoplasmic reticulum in Arabidopsis as a result of its interactions with ethylene receptors. Membrane association of CTR1 is reduced by mutations that eliminate ethylene receptors and by a mutation in CTR1 that reduces its ability to bind to the ethylene receptor ETR1. Direct evidence that CTR1 is part of an ethylene receptor signaling complex was obtained by co-purification of the ethylene receptor ETR1 with a tagged version of CTR1 from an Arabidopsis membrane extract. The histidine kinase activity of ETR1 is not required for its association with CTR1, based on co-purification of tagged ETR1 mutants and CTR1 after expression in a transgenic yeast system. These data demonstrate that CTR1 is part of an ethylene receptor signaling complex in Arabidopsis and support a model in which localization of CTR1 to the endoplasmic reticulum is necessary for its function. Additional data that demonstrate a post-transcriptional effect of ethylene upon the expression of CTR1 suggest that production of ethylene receptor signaling complexes may be coordinately regulated.