title: A UV-B-specific signaling component orchestrates plant UV protection.
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.
authors.affiliation: Plant Science Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, UK.
authors.forename: Bobby A
authors.initials: BA
authors.lastname: Brown
authors.forename: Catherine
authors.initials: C
authors.lastname: Cloix
authors.forename: Guang Huai
authors.initials: GH
authors.lastname: Jiang
authors.forename: Eirini
authors.initials: E
authors.lastname: Kaiserli
authors.forename: Pawel
authors.initials: P
authors.lastname: Herzyk
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Kliebenstein
authors.forename: Gareth I
authors.initials: GI
authors.lastname: Jenkins
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D006657:Histones / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D002843:Chromatin; D017931:DNA Primers; C109254:HY5 protein, Arabidopsis; D006657:Histones; D009687:Nuclear Proteins