Lapadat M A, Deerfield D W, Pedersen L G, Spremulli L L
Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290.
Proteins. 1990;8(3):237-50. doi: 10.1002/prot.340080306.
Comparative molecular modeling has been used to generate several possible structures for the G-domain of chloroplast elongation factor Tu (EF-Tu(chl)) based on the crystallographic data of the homologous E. coli protein. EF-Tu(chl) contains a 10 amino acid insertion not present in the E. coli protein and this region has been modeled based on its predicted secondary structure. The insertion appears to lie on the surface of the protein. Its orientation could not be determined unequivocally but several likely structures for the nucleotide binding domain of EF-Tu(chl) have been developed. The effects of the presence of water in the Mg2+ coordination sphere and of the protonation state of the GDP ligand on the conformation of the guanine nucleotide binding site have been examined. Relative binding constants of several guanine nucleotide analogs for EF-Tu(chl) have been obtained. The interactions between EF-Tu(chl) and GDP predicted to be important by the models that have been developed are discussed in relation to the nucleotide binding properties of this factor and to the interactions proposed to be important in the binding of guanine nucleotides to related proteins.
基于同源大肠杆菌蛋白的晶体学数据，比较分子建模已用于生成叶绿体延伸因子Tu（EF-Tu（chl））G结构域的几种可能结构。EF-Tu（chl）含有一段大肠杆菌蛋白中不存在的10个氨基酸的插入序列，该区域已根据其预测的二级结构进行建模。该插入序列似乎位于蛋白质表面。其方向无法明确确定，但已开发出EF-Tu（chl）核苷酸结合结构域的几种可能结构。研究了Mg2+配位球中存在水以及GDP配体质子化状态对鸟嘌呤核苷酸结合位点构象的影响。已获得几种鸟嘌呤核苷酸类似物与EF-Tu（chl）的相对结合常数。结合已开发的模型预测的EF-Tu（chl）与GDP之间的相互作用，结合该因子的核苷酸结合特性以及鸟嘌呤核苷酸与相关蛋白结合中提出的重要相互作用进行了讨论。
