Better explicating the strengths and shortcomings of these models will help refine projections and improve transparency in the years ahead.
Image credit: Witsawat.S.
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Edited by Alexander N. Glazer, University of California System, Oakland, CA (received for review August 22, 2005)
Abstract
UV-B radiation in sunlight has diverse effects on humans, animals, plants, and microorganisms. UV-B can cause damage to molecules and cells, and consequently organisms need to protect against and repair UV damage to survive in sunlight. In plants, low nondamaging levels of UV-B stimulate transcription of genes involved in UV-protective responses. However, remarkably little is known about the underlying mechanisms of UV-B perception and signal transduction. Here we report that Arabidopsis UV RESISTANCE LOCUS 8 (UVR8) is a UV-B-specific signaling component that orchestrates expression of a range of genes with vital UV-protective functions. Moreover, we show that UVR8 regulates expression of the transcription factor HY5 specifically when the plant is exposed to UV-B. We demonstrate that HY5 is a key effector of the UVR8 pathway, and that it is required for survival under UV-B radiation. UVR8 has sequence similarity to the eukaryotic guanine nucleotide exchange factor RCC1, but we found that it has little exchange activity. However, UVR8, like RCC1, is located principally in the nucleus and associates with chromatin via histones. Chromatin immunoprecipitation showed that UVR8 associates with chromatin in the HY5 promoter region, providing a mechanistic basis for its involvement in regulating transcription. We conclude that UVR8 defines a UV-B-specific signaling pathway in plants that orchestrates the protective gene expression responses to UV-B required for plant survival in sunlight.
Footnotes
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↵ ∥ To whom correspondence should be addressed. E-mail: g.jenkins{at}bio.gla.ac.uk.
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↵ † B.A.B. and C.C. contributed equally to this work.
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↵ ‡ Present address: National Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
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Author contributions: G.I.J. designed research; B.A.B., C.C., G.H.J., E.K., and D.J.K. performed research; B.A.B., C.C., G.H.J., and D.J.K. contributed new reagents/analytic tools; B.A.B., C.C., G.H.J., E.K., P.H., D.J.K., and G.I.J. analyzed data; and G.I.J. wrote the paper.
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Conflict of interest statement: No conflicts declared.
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This paper was submitted directly (Track II) to the PNAS office.
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Abbreviations: FDR, false discovery rate; CHS, chalcone synthase; GEF, guanine nucleotide exchange factor.
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Data deposition: The Affymetrix microarray expression data reported in this paper have been deposited in the National Center for Biotechnology Information's Gene Expression Omnibus (GEO) database (accession no. GSE3533).
- Copyright © 2005, The National Academy of Sciences
A UV-B-specific signaling component orchestrates plant UV protection
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