The COP1-SPA1 interaction defines a critical step in phytochrome A-mediated regulation of HY5 activity.
Arabidopsis COP1 is a constitutive repressor of photomorphogenesis that interacts with photomorphogenesis-promoting factors such as HY5 to promote their proteasome-mediated degradation. SPA1 is a repressor of phytochrome A-mediated responses to far-red light. Here we report that COP1 acts as part of a large protein complex and interacts with SPA1 in a light-dependent manner. We further demonstrate the E3 ubiquitin ligase activity of COP1 on HY5 in vitro and the alteration of that activity by SPA1. Thus, the COP1-SPA1 interaction defines a critical step in coordinating COP1-mediated ubiquitination and subsequent degradation of HY5 with PHYA signaling.
Saijo
Yusuke
Y
Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA.
Sullivan
James A
JA
Wang
Haiyang
H
Yang
Jianping
J
Shen
Yunping
Y
Rubio
Vicente
V
Ma
Ligeng
L
Hoecker
Ute
U
Deng
Xing Wang
XW
D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors; D009687:Nuclear Proteins / Q000378:metabolism*; D010834:Phytochrome / Q000378:metabolism*; D051942:Phytochrome A; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; C497973:PHYA protein, Arabidopsis; D051942:Phytochrome A; D010834:Phytochrome; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases