title: UV-B-responsive association of the Arabidopsis bZIP transcription factor ELONGATED HYPOCOTYL5 with target genes, including its own promoter.
abstract: In plants subjected to UV-B radiation, responses are activated that minimize damage caused by UV-B. The bZIP transcription factor ELONGATED HYPOCOTYL5 (HY5) acts downstream of the UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8) and promotes UV-B-induced photomorphogenesis and acclimation. Expression of HY5 is induced by UV-B; however, the transcription factor(s) that regulate HY5 transcription in response to UV-B and the impact of UV-B on the association of HY5 with its target promoters are currently unclear. Here, we show that HY5 binding to the promoters of UV-B-responsive genes is enhanced by UV-B in a UVR8-dependent manner in Arabidopsis thaliana. In agreement, overexpression of REPRESSOR OF UV-B PHOTOMORPHOGENESIS2, a negative regulator of UVR8 function, blocks UV-B-responsive HY5 enrichment at target promoters. Moreover, we have identified a T/G-box in the HY5 promoter that is required for its UV-B responsiveness. We show that HY5 and its homolog HYH bind to the T/G(HY5)-box cis-acting element and that they act redundantly in the induction of HY5 expression upon UV-B exposure. Therefore, HY5 is enriched at target promoters in response to UV-B in a UVR8 photoreceptor-dependent manner, and HY5 and HYH interact directly with a T/G-box cis-acting element of the HY5 promoter, mediating the transcriptional activation of HY5 in response to UV-B.
authors.affiliation: Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland.
authors.forename: Melanie
authors.initials: M
authors.lastname: Binkert
authors.affiliation: Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Kozma-Bognár
authors.affiliation: Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary.
authors.forename: Kata
authors.initials: K
authors.lastname: Terecskei
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: De Veylder
authors.affiliation: Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary School of Biological Sciences, University of Edinburgh, EH9 3JR Edinburgh, United Kingdom.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Nagy
authors.affiliation: Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland roman.ulm@unige.ch.
authors.forename: Roman
authors.initials: R
authors.lastname: Ulm
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D009024:Morphogenesis / Q000235:genetics / Q000528:radiation effects; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D002352:Carrier Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C109254:HY5 protein, Arabidopsis; C457459:HYH protein, Arabidopsis; D009687:Nuclear Proteins; C525052:Uvr8 protein, Arabidopsis