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The COP1-SPA1 interaction defines a critical step in phytochrome A-mediated regulation of HY5 activity.

ABSTRACT: 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.

SUBMITTER: Saijo Y

PROVIDER: S-EPMC280614 | biostudies-literature | 2003 Nov

REPOSITORIES: biostudies-literature

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The COP1-SPA1 interaction defines a critical step in phytochrome A-mediated regulation of HY5 activity.

Saijo Yusuke Y 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

Genes & development 20031101 21

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 SPA ...[more]

PMID: 14597662

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