PMID- 20605855 OWN - NLM STAT- MEDLINE DCOM- 20101230 LR - 20211020 IS - 1532-298X (Electronic) IS - 1040-4651 (Print) IS - 1040-4651 (Linking) VI - 22 IP - 7 DP - 2010 Jul TI - Arabidopsis PHYTOCHROME INTERACTING FACTOR proteins promote phytochrome B polyubiquitination by COP1 E3 ligase in the nucleus. PG - 2370-83 LID - 10.1105/tpc.109.072520 [doi] AB - Many plant photoresponses from germination to shade avoidance are mediated by phytochrome B (phyB). In darkness, phyB exists as the inactive Pr in the cytosol but upon red (R) light treatment, the active Pfr translocates into nuclei to initiate signaling. Degradation of phyB Pfr likely regulates signal termination, but the mechanism is not understood. Here, we show that phyB is stable in darkness, but in R, a fraction of phyB translocates into nuclei and becomes degraded by 26S proteasomes. Nuclear phyB degradation is mediated by COP1 E3 ligase, which preferentially interacts with the PhyB N-terminal region (PhyB-N). PhyB-N polyubiquitination by CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) in vitro can be enhanced by different PHYTOCHROME INTERACTING FACTOR (PIF) proteins that promote COP1/PhyB interaction. Consistent with these results, nuclear phyB accumulates to higher levels in pif single and double mutants and in cop1-4. Our results identify COP1 as an E3 ligase for phyB and other stable phytochromes and uncover the mechanism by which PIFs negatively regulate phyB levels. FAU - Jang, In-Cheol AU - Jang IC AD - Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10065, USA. FAU - Henriques, Rossana AU - Henriques R FAU - Seo, Hak Soo AU - Seo HS FAU - Nagatani, Akira AU - Nagatani A FAU - Chua, Nam-Hai AU - Chua NH LA - eng GR - R01 GM044640/GM/NIGMS NIH HHS/United States GR - R56 GM044640/GM/NIGMS NIH HHS/United States GR - GM44640/GM/NIGMS NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural DEP - 20100706 PL - England TA - Plant Cell JT - The Plant cell JID - 9208688 RN - 0 (Arabidopsis Proteins) RN - 136250-22-1 (Phytochrome B) RN - EC 2.3.2.27 (AT2G32950 protein, Arabidopsis) RN - EC 2.3.2.27 (Ubiquitin-Protein Ligases) SB - IM MH - Alleles MH - Arabidopsis/genetics/*metabolism MH - Arabidopsis Proteins/metabolism/*physiology MH - Cell Nucleus/enzymology/*metabolism MH - Mutation MH - Phytochrome B/*metabolism MH - Ubiquitin-Protein Ligases/*metabolism MH - Ubiquitination PMC - PMC2929111 EDAT- 2010/07/08 06:00 MHDA- 2010/12/31 06:00 PMCR- 2011/07/01 CRDT- 2010/07/08 06:00 PHST- 2010/07/08 06:00 [entrez] PHST- 2010/07/08 06:00 [pubmed] PHST- 2010/12/31 06:00 [medline] PHST- 2011/07/01 00:00 [pmc-release] AID - tpc.109.072520 [pii] AID - 072520 [pii] AID - 10.1105/tpc.109.072520 [doi] PST - ppublish SO - Plant Cell. 2010 Jul;22(7):2370-83. doi: 10.1105/tpc.109.072520. Epub 2010 Jul 6.