Identification of a structural motif that confers specific interaction with the WD40 repeat domain of Arabidopsis COP1
Identification of a structural motif that confers specific interaction with the WD40 repeat domain of Arabidopsis COP1
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DOI：
10.1093/emboj/20.1.118
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发表时间：
2001-01-15
期刊：
影响因子：
11.4
通讯作者：
Deng, XW
中科院分区：
文献类型：
--
作者：
Holm, M;Hardtke, CS;Deng, XW
拟南芥COP1是一种光形态建成抑制因子，能够直接与光形态建成促进因子HY5相互作用，这种相互作用导致26S蛋白酶体对HY5的靶向性降解。在这里，我们表征了COP1与HY5和两个新蛋白的WD40重复结构域介导的相互作用。对这些相互作用伙伴的突变分析表明，一个保守的基序负责与WD40结构域的相互作用。这个新的基序具有核心序列V-P-E/D-Phi-G(Phi=疏水残基)，与上游4-5个带负电荷的残基结合，通过疏水和离子相互作用与COP1WD40重复结构域的P-螺旋桨组件的特定表面积相互作用。COP1WD40结构域中的几个残基对与该基序的相互作用至关重要。COP1WD40结构域或HY5基序上的点突变取消了酵母中COP1和HY5之间的相互作用，导致转基因植物中HY5的降解显著减少，这一事实证实了这种定义的相互作用的生物学意义。
Arabidopsis COP1 is a photomorphogenesis repressor capable of directly interacting with the photomorphogenesis-promoting factor HY5, This interaction between HY5 and COP1 results in targeted degradation of HY5 by the 26S proteasome. Here we characterized the WD40 repeat domain-mediated interactions of COP1 with HY5 and two new proteins. Mutational analysis of those interactive partners revealed a conserved motif responsible for the interaction with the WD40 domain. This novel motif, with the core sequence V-P-E/D-phi -G (phi = hydrophobic residue) in conjunction with an upstream stretch of 4-5 negatively charged residues, interacts with a defined surface area of the P-propeller assembly of the COP1 WD40 repeat domain through both hydrophobic and ionic interactions. Several residues in the COP1 WD40 domain that are critical for the interaction with this motif have been revealed. The fact that point mutations either in the COP1 WD40 domain or in the HY5 motif that abolish the interaction between COP1 and HY5 in yeast result in a dramatic reduction of HY5 degradation in transgenic plants validates the biological significance of this defined interaction.