title: Lysine 206 in Arabidopsis phytochrome A is the major site for ubiquitin-dependent protein degradation.
abstract: Phytochrome A (phyA) is a light labile phytochrome that mediates plant development under red/far-red light condition. Degradation of phyA is initiated by red light-induced phyA-ubiquitin conjugation through the 26S proteasome pathway. The N-terminal of phyA is known to be important in phyA degradation. To determine the specific lysine residues in the N-terminal domain of phyA involved in light-induced ubiquitination and protein degradation, we aligned the amino acid sequence of the N-terminal domain of Arabidopsis phyA with those of phyA from other plant species. Based on the alignment results, phytochrome over-expressing Arabidopsis plants were generated. In particular, wild-type and mutant (substitutions of conserved lysines by arginines) phytochromes fused with GFP were expressed in phyA(-)211 Arabidopsis plants. Degradation kinetics of over-expressed phyA proteins revealed that degradation of the K206R phyA mutant protein was delayed. Delayed phyA degradation of the K206R phyA mutant protein resulted in reduction of red-light-induced phyA-ubiquitin conjugation. Furthermore, seedlings expressing the K206R phyA mutant protein showed an enhanced phyA response under far-red light, resulting in inhibition of hypocotyl elongation as well as cotyledon opening. Together, these results suggest that lysine 206 is the main lysine for rapid ubiquitination and protein degradation of Arabidopsis phytochrome A.
authors: Graduate School of Biotechnology and Plant Metabolism Research Center, Kyung Hee University, Yongin 17104, Korea.
authors: Kaewta
authors: K
authors: Rattanapisit
authors: Graduate School of Biotechnology and Plant Metabolism Research Center, Kyung Hee University, Yongin 17104, Korea.
authors: Man-Ho
authors: MH
authors: Cho
authors: Graduate School of Biotechnology and Plant Metabolism Research Center, Kyung Hee University, Yongin 17104, Korea shbhoo@khu.ac.kr.
authors: Seong Hee
authors: SH
authors: Bhoo
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism* / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D018548:Cotyledon / Q000502:physiology; D018546:Hypocotyl / Q000502:physiology; D008027:Light; D008239:Lysine / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D051942:Phytochrome A / Q000378:metabolism* / Q000502:physiology; D030821:Plants, Genetically Modified / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D015398:Signal Transduction; D014157:Transcription Factors; D057149:Ubiquitinated Proteins / Q000378:metabolism*; D054875:Ubiquitination; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C497973:PHYA protein, Arabidopsis; D051942:Phytochrome A; D014157:Transcription Factors; D057149:Ubiquitinated Proteins; D014452:Ubiquitins; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D008239:Lysine
keywords: light-induced phyA degradation; phytochrome A; proteasome; ubiquitination