ETHYLENE-INSENSITIVE5 encodes a 5′→3′ exoribonuclease required for regulation of the EIN3-targeting F-box proteins EBF1/2
- Gabriela Olmedo*,†,‡,
- Hongwei Guo*,‡,§,
- Brian D. Gregory*,‡,
- Saeid D. Nourizadeh‡,¶,
- Laura Aguilar-Henonin*,†,
- Hongjiang Li§,
- Fengying An§,
- Plinio Guzman*,†, and
- Joseph R. Ecker*,‖
- *Plant Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037;
- †Departamento de Ingeniería Genética de Plantas, Cinvestav, Campus Guanajuato, Apartado Postal 629, 36500 Irapuato, Guanajuato, México;
- §National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China; and
- ¶Department of Biology, University of Pennsylvania, Philadelphia, PA 19104
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Contributed by Joseph R. Ecker, July 2, 2006
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↵ ‡G.O., H.G., B.D.G., and S.D.N. contributed equally to this work.
Abstract
Ethylene is a gaseous plant growth regulator that controls a multitude of developmental and stress responses. Recently, the levels of Arabidopsis EIN3 protein, a key transcription factor mediating ethylene-regulated gene expression, have been demonstrated to increase in response to the presence of ethylene gas. Furthermore, in the absence of ethylene, EIN3 is quickly degraded through a ubiquitin/proteasome pathway mediated by two F-box proteins, EBF1 and EBF2. Here we report the identification of ETHYLENE-INSENSITIVE5 as the 5′→3′ exoribonuclease XRN4. Specifically, we demonstrate that EIN5 is a component of the ethylene signal transduction cascade acting downstream of CTR1 that is required for ethylene-mediated gene expression changes. Furthermore, we find that the ethylene insensitivity of ein5 mutant plants is a consequence of the over-accumulation of EBF1 and EBF2 mRNAs resulting in the under-accumulation of EIN3 even in the presence of ethylene gas. Together, our results suggest that the role of EIN5 in ethylene perception is to antagonize the negative feedback regulation on EIN3 by promoting EBF1 and EBF2 mRNA decay, which consequently allows the accumulation of EIN3 protein to trigger the ethylene response.
Footnotes
- ‖To whom correspondence should be addressed. E-mail: ecker{at}salk.edu
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This contribution is part of the special series of Inaugural Articles by members of the National Academy of Sciences elected on April 25, 2006.
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Author contributions: G.O., H.G., B.D.G., S.D.N., P.G., and J.R.E. designed research; G.O., H.G., B.D.G., S.D.N., L.A.-H., H.L., F.A., and P.G. performed research; G.O., H.G., B.D.G., S.D.N., L.A.-H., H.L., F.A., P.G., and J.R.E. analyzed data; and G.O., B.D.G., and J.R.E. wrote the paper.
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Conflict of interest statement: No conflicts declared.
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Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession no. BT026022), and gene expression and tiling array data have been deposited in the Gene Expression Omnibus database, www.ncbi.nlm.nih.gov/geo (accession no. GSE5174).
- Abbreviation:
- ACC,
- 1-aminocyclopropane-1-carboxylic acid.
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Freely available online through the PNAS open access option.
- © 2006 by The National Academy of Sciences of the USA
