GENETIC AND MOLECULAR ANALYSIS OF AN ALLELIC SERIES OF COP1 MUTANTS SUGGESTS FUNCTIONAL ROLES FOR THE MULTIPLE PROTEIN DOMAINS
GENETIC AND MOLECULAR ANALYSIS OF AN ALLELIC SERIES OF COP1 MUTANTS SUGGESTS FUNCTIONAL ROLES FOR THE MULTIPLE PROTEIN DOMAINS
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DOI：
10.1105/tpc.6.4.487
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发表时间：
1994-04-01
期刊：
影响因子：
11.6
通讯作者：
DENG, XW
中科院分区：
文献类型：
--
作者：
MCNELLIS, TW;VONARNIM, AG;DENG, XW
拟南芥COP 1蛋白由组成型光形态发生基因座1编码，是一种重要的调控分子，在黑暗中抑制光形态发生发育以及光生长植物对光周期、日终远红光处理和红光/远红光比率的反应能力中发挥作用。COP 1蛋白包含三个可识别的结构域：从N末端开始，它们是锌结合基序、推定的卷曲螺旋区和具有与三聚体G蛋白（G（β））的P亚基同源的多个WD-40重复的结构域。为了理解这些结构基序的功能含义，根据光形态发生幼苗在黑暗条件下的发育特征，分离出17个COP 1基因的隐性突变体。这些突变定义了三种表型类别：弱，强和致命。属于致死类别的突变可能是COP 1的无效突变。对积累突变形式COP 1蛋白的九个突变等位基因的分子分析表明，G（β）蛋白同源结构域的破坏或C末端56个氨基酸的去除都对COP 1功能有害。假定卷曲螺旋和G（β）蛋白同源结构域之间的短氨基酸片段的框内缺失或插入强烈损害COP 1功能。然而，一个突变导致的COP 1蛋白只有N-末端282个氨基酸，包括锌结合和卷曲螺旋结构域，产生了弱的表型缺陷。这些结果表明，COP 1的N-末端的一半单独保留了一些活性，而破坏的C-末端结构域掩盖了这种剩余的活性。
The Arabidopsis protein COP1, encoded by the CONSTITUTIVE PHOTOMORPHOGENIC locus 1, is an essential regulatory molecule that plays a role in the repression of photomorphogenic development in darkness and in the ability of light-grown plants to respond to photoperiod, end-of-day far-red treatment, and ratio of red/far-red light. The COP1 protein contains three recognizable structural domains: starting from the N terminus, they are the zinc binding motif, the putative coiled-coil region, and the domain with multiple WD-40 repeats homologous to the P subunit of trimeric G-proteins (G(beta)) To understand the functional implications of these structural motifs, 17 recessive mutations of the COP1 gene have been isolated based on their constitutive photomorphogenic seedling development in darkness. These mutations define three phenotypic classes: weak, strong, and lethal. The mutations that fall into the lethal class are possible null mutations of COP1. Molecular analysis of the nine mutant alleles that accumulated mutated forms of COP1 protein revealed that disruption of the G(beta)-protein homology domain or removal of the very C-terminal 56 amino acids are both deleterious to COP1 function. In-frame deletions or insertions of short amino acid stretches between the putative coiled-coil and G(beta)-protein homology domains strongly compromised COP1 function. However, a mutation resulting in a COP1 protein with only the N-terminal 282 amino acids, including both the zinc binding and the coiled-coil domains, produced a weak phenotypic defect. These results indicated that the N-terminal half of COP1 alone retains some activity and a disrupted C-terminal domain masks this remaining activity.