Thépaut Michel, Maiorano Domenico, Guichou Jean-François, Augé Marie-Thérèse, Dumas Christian, Méchali Marcel, Padilla André
Centre de Biochimie Structurale, CNRS UMR 5048 INSERM UMR 554, 15 Av Charles Flahault, 34060 Montpellier, France.
J Mol Biol. 2004 Sep 3;342(1):275-87. doi: 10.1016/j.jmb.2004.06.065.
We have determined the crystal structure of the coiled-coil domain of human geminin, a DNA synthesis inhibitor in higher eukaryotes. We show that a peptide encompassing the five heptad repeats of the geminin leucine zipper (LZ) domain is a dimeric parallel coiled coil characterized by a unique pattern of internal polar residues and a negatively charged surface that may target the basic domain of interacting partners. We show that the LZ domain itself is not sufficient to inhibit DNA synthesis but upstream and downstream residues are required. Analysis of a functional form of geminin by density sedimentation indicates an oligomeric structure. X-ray solution scattering experiments performed on a non-functional form of geminin having upstream basic residues and the LZ domain show a tetramer structure. Altogether, these results give a consistent identification and mapping of geminin interacting regions onto structurally important domains. They also suggest that oligomerization properties of geminin may be implicated in its inhibitory activity of DNA synthesis.
我们已经确定了人类双微体蛋白卷曲螺旋结构域的晶体结构，双微体蛋白是高等真核生物中的一种DNA合成抑制剂。我们发现，包含双微体蛋白亮氨酸拉链（LZ）结构域五个七肽重复序列的肽是一种二聚体平行卷曲螺旋，其特征在于内部极性残基的独特模式和一个带负电荷的表面，该表面可能靶向相互作用伙伴的碱性结构域。我们表明，LZ结构域本身不足以抑制DNA合成，但上游和下游残基是必需的。通过密度沉降对双微体蛋白的功能形式进行分析表明其具有寡聚结构。对具有上游碱性残基和LZ结构域的双微体蛋白非功能形式进行的X射线溶液散射实验显示其为四聚体结构。总之，这些结果对双微体蛋白相互作用区域进行了一致的鉴定，并将其定位到结构上重要的结构域。它们还表明，双微体蛋白的寡聚化特性可能涉及其对DNA合成的抑制活性。
