PMID- 30352855 OWN - NLM STAT- MEDLINE DCOM- 20190501 LR - 20191210 IS - 1091-6490 (Electronic) IS - 0027-8424 (Print) IS - 0027-8424 (Linking) VI - 115 IP - 45 DP - 2018 Nov 6 TI - COP1 SUPPRESSOR 4 promotes seedling photomorphogenesis by repressing CCA1 and PIF4 expression in Arabidopsis. PG - 11631-11636 LID - 10.1073/pnas.1813171115 [doi] AB - CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and DE-ETIOLATED 1 (DET1) are founding components of two central repressor complexes of photomorphogenesis that trigger the degradation of a larger number of photomorphogenic-promoting factors in darkness. Here, we identify COP1 SUPPRESSOR 4 (CSU4) as a genetic suppressor of the cop1-6 mutation. Mutations in CSU4 largely rescued the constitutively photomorphogenic phenotype of cop1-6 and det1-1 in darkness. Loss of CSU4 function resulted in significantly longer hypocotyl in the light. Further biochemical studies revealed that CSU4 physically interacts with CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1) and negatively regulates its transcriptional repression activity toward its targets. CSU4 represses the expression of CCA1 in the early morning and of PHYTOCHROME INTERACTING FACTOR 4 (PIF4) in the early evening. Our study suggests that CSU4 acts as a negative regulator of CCA1 via physically associating with CCA1, which in turn, likely serves to repress expression of CCA1 and PIF4 to promote photomorphogenesis. FAU - Zhao, Xianhai AU - Zhao X AD - Institute of Plant and Food Sciences, Department of Biology, Southern University of Science and Technology, 518055 Shenzhen, China. FAU - Jiang, Yan AU - Jiang Y AD - Institute of Plant and Food Sciences, Department of Biology, Southern University of Science and Technology, 518055 Shenzhen, China. AD - State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, 210095 Nanjing, China. FAU - Li, Jian AU - Li J AUID- ORCID: 0000-0002-1287-8932 AD - State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, 100871 Beijing, China. FAU - Huq, Enamul AU - Huq E AUID- ORCID: 0000-0001-7692-5139 AD - Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712. FAU - Chen, Z Jeffrey AU - Chen ZJ AUID- ORCID: 0000-0001-5006-8036 AD - Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712. FAU - Xu, Dongqing AU - Xu D AD - State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, 210095 Nanjing, China; dongqingxu@njau.edu.cn deng@pku.edu.cn. FAU - Deng, Xing Wang AU - Deng XW AD - Institute of Plant and Food Sciences, Department of Biology, Southern University of Science and Technology, 518055 Shenzhen, China; dongqingxu@njau.edu.cn deng@pku.edu.cn. AD - State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, 100871 Beijing, China. LA - eng GR - R01 GM047850/GM/NIGMS NIH HHS/United States GR - R01 GM109076/GM/NIGMS NIH HHS/United States GR - R01 GM114297/GM/NIGMS NIH HHS/United States GR - R37 GM047850/GM/NIGMS NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, Non-U.S. Gov't DEP - 20181023 PL - United States TA - Proc Natl Acad Sci U S A JT - Proceedings of the National Academy of Sciences of the United States of America JID - 7505876 RN - 0 (Arabidopsis Proteins) RN - 0 (Basic Helix-Loop-Helix Transcription Factors) RN - 0 (CCA1 protein, Arabidopsis) RN - 0 (DET1 protein, Arabidopsis) RN - 0 (Intracellular Signaling Peptides and Proteins) RN - 0 (Nuclear Proteins) RN - 0 (PIF4 protein, Arabidopsis) RN - 0 (Protein Isoforms) RN - 0 (Repressor Proteins) RN - 0 (Transcription Factors) RN - EC 2.3.2.27 (AT2G32950 protein, Arabidopsis) RN - EC 2.3.2.27 (Ubiquitin-Protein Ligases) SB - IM MH - Arabidopsis/*genetics/growth & development/metabolism/radiation effects MH - Arabidopsis Proteins/*genetics/metabolism MH - Basic Helix-Loop-Helix Transcription Factors/*genetics/metabolism MH - Darkness MH - Gene Expression Regulation, Developmental MH - *Gene Expression Regulation, Plant MH - Intracellular Signaling Peptides and Proteins MH - Mutation MH - Nuclear Proteins/genetics/metabolism MH - Photosynthesis/genetics MH - Plant Development/*genetics MH - Plant Leaves/*genetics/growth & development/metabolism/radiation effects MH - Protein Binding MH - Protein Isoforms/genetics/metabolism MH - Repressor Proteins/*genetics/metabolism MH - Seedlings/genetics/growth & development/metabolism/radiation effects MH - Signal Transduction MH - Transcription Factors/*genetics/metabolism MH - Transcription, Genetic MH - Ubiquitin-Protein Ligases/genetics/metabolism PMC - PMC6233069 OTO - NOTNLM OT - CCA1 OT - COP1 OT - CSU4 OT - PIF4 OT - photomorphogenesis COIS- The authors declare no conflict of interest. EDAT- 2018/10/26 06:00 MHDA- 2019/05/02 06:00 PMCR- 2019/05/06 CRDT- 2018/10/25 06:00 PHST- 2018/10/26 06:00 [pubmed] PHST- 2019/05/02 06:00 [medline] PHST- 2018/10/25 06:00 [entrez] PHST- 2019/05/06 00:00 [pmc-release] AID - 1813171115 [pii] AID - 201813171 [pii] AID - 10.1073/pnas.1813171115 [doi] PST - ppublish SO - Proc Natl Acad Sci U S A. 2018 Nov 6;115(45):11631-11636. doi: 10.1073/pnas.1813171115. Epub 2018 Oct 23.