With the progress of plant genome research, more than 50 plant metallothionein like (MT-L) genes have been found, but only several MT-L proteins have been detected and no experimental structural information for MT-L proteins has been reported so far. Since detailed knowledge of the protein tertiary structure is required to understand its biological function, a method is needed to determine the structure of these proteins. In this study, the structural data of known mammal MT was used to determine the interatomic distance constraints of the CXC and CXXC motifs and the metal sulfur chelating cluster. Then several possible MT conformations were predicted using a distance geometry algorithm. The statistical analysis was used to select those with much lower target function values and lower conformation energies as the predicted tertiary structural models of the cysteine rich (CR) domains of these proteins. A suitable prediction method for modeling the CR domain of the plant MT-L protein was constructed. The accurately predicted result for the known structure of an MT protein from blue crab suggests that this method is practicable. The tertiary structures of CR domains of rape MT-L protein LSC54 was then modeled with this method.
植物类金属硫蛋白半胱氨酸富含区结构的建模
何红珍 朱春明 吕 暾 张日清 赵南明 刘进元*
（清华大学生物科学与技术系，生物膜与膜生物工程国家重点实验室，北京100084）
摘要: 详细了解蛋白质的三级结构信息有助于理解其生物学功能。随着植物基因组研究的进展 ,已发现了 50多个植物类金属硫蛋白 (Metallothionein-Like ,MT-L)基因。但至今只有少数几个MT-L蛋白得到了纯化 ,而其结构尚无报道 ,因此有必要建立分析这类蛋白结构特征的方法。本研究根据已知的哺乳动物MT的结构数据 ,分析得出了CXC、CXXC模式和金属 硫络合簇结构原子间的距离限制条件 ,并用距离几何算法计算得出预测蛋白可能的构象 ;然后通过统计分析筛选出目标函数值显著较小、构象能低的结构作为这些蛋白半胱氨酸富含区的预测结构 ,由此建成了适合于植物类金属硫蛋白半胱氨酸富含区的结构预测方法。从应用该方法正确地预测出了已知结构的蓝蟹MT的结构来看 ,该方法是可行的。并用该方法预测了油菜MT_L蛋白的半胱氨酸富含区的结构。
关键词： 植物类金属硫蛋白；半胱氨酸富含区；三级结构预测；距离几何算法
通讯作者. E-mail:<liujy @ mail.tsinghua.edu.cn>.
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