Arabidopsis CULLIN4-damaged DNA binding protein 1 interacts with CONSTITUTIVELY PHOTOMORPHOGENIC1-SUPPRESSOR OF PHYA complexes to regulate photomorphogenesis and flowering time.
CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) possesses E3 ligase activity and promotes degradation of key factors involved in the light regulation of plant development. The finding that CULLIN4 (CUL4)-Damaged DNA Binding Protein1 (DDB1) interacts with DDB1 binding WD40 (DWD) proteins to act as E3 ligases implied that CUL4-DDB1 may associate with COP1-SUPPRESSOR OF PHYA (SPA) protein complexes, since COP1 and SPAs are DWD proteins. Here, we demonstrate that CUL4-DDB1 physically associates with COP1-SPA complexes in vitro and in vivo, likely via direct interaction of DDB1 with COP1 and SPAs. The interactions between DDB1 and COP1, SPA1, and SPA3 were disrupted by mutations in the WDXR motifs of MBP-COP1, His-SPA1, and His-SPA3. CUL4 cosuppression mutants enhanced weak cop1 photomorphogenesis and flowered early under short days. Early flowering of short day-grown cul4 mutants correlated with increased FLOWERING LOCUS T transcript levels, whereas CONSTANS transcript levels were not altered. De-etiolated1 and COP1 can bind DDB1 and may work with CUL4-DDB1 in distinct complexes, but they mediate photomorphogenesis in concert. Thus, a series of CUL4-DDB1-COP1-SPA E3 ligase complexes may mediate the repression of photomorphogenesis and, possibly, of flowering time.
Chen
Haodong
H
Peking-Yale Joint Center for Plant Molecular Genetics and Agro-biotechnology, National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China.
Huang
Xi
X
Gusmaroli
Giuliana
G
Terzaghi
William
W
Lau
On Sun
OS
Yanagawa
Yuki
Y
Zhang
Yu
Y
Li
Jigang
J
Lee
Jae-Hoon
JH
Zhu
Danmeng
D
Deng
Xing Wang
XW
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; C514806:CULLIN4 protein, Arabidopsis; D018797:Cell Cycle Proteins; D044842:Cullin Proteins; C517426:DDB1a protein, Arabidopsis; D004268:DNA-Binding Proteins; D018749:RNA, Plant; C118571:SPA1 protein, Arabidopsis; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases