Stoop-Myer C, Torii K U, McNellis T W, Coleman J E, Deng X W
Department of Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8104, USA.
Plant J. 1999 Dec;20(6):713-7. doi: 10.1046/j.1365-313x.1999.00639.x.
Arabidopsis seedlings exhibit distinct developmental patterns according to their light environment: photomorphogenesis in the light and etiolation or skotomorphogenesis in darkness. COP1 acts within the nucleus to repress photomorphogenesis in darkness, while light depletes COP1 from nucleus and abrogates this repression. COP1 contains three structural modules: a RING finger followed by a coiled-coil domain, and a WD40 repeat domain at the C-terminus. By introducing various domain deletion mutants of COP1 into cop1 null mutant backgrounds, we show that all three domains are essential for the function of COP1 in vivo. Interestingly, a fragment containing the N-terminal 282 amino acids of COP1 (N282) with both the RING finger and coiled-coil modules is sufficient to rescue the lethality of the cop1 null mutations at low expression level. However, high expression levels of the N282 fragment result in a phenocopy of the cop1 null mutation. The sensitivity of the seedling to levels of N282 could reflect the importance of the abundance of COP1 for the appropriate regulation of photomorphogenic development.
在光照下进行光形态建成，在黑暗中进行黄化或暗形态建成。COP1在细胞核内发挥作用，在黑暗中抑制光形态建成，而光照使COP1从细胞核中耗尽并消除这种抑制作用。COP1包含三个结构模块：一个环指结构，其后是一个卷曲螺旋结构域，以及位于C末端的WD40重复结构域。通过将COP1的各种结构域缺失突变体导入cop1缺失突变体背景中，我们发现所有这三个结构域对于COP1在体内的功能都是必不可少的。有趣的是，一个包含COP1 N端282个氨基酸（N282）的片段，同时具有环指结构和卷曲螺旋模块，在低表达水平时足以挽救cop1缺失突变的致死性。然而，N282片段的高表达水平会导致cop1缺失突变的表型模拟。幼苗对N282水平的敏感性可能反映了COP1丰度对于光形态建成发育的适当调节的重要性。
