Zhang Y, Spremulli L L
Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
J Biol Chem. 1998 Oct 23;273(43):28142-8. doi: 10.1074/jbc.273.43.28142.
The crystal structure of the complex between Escherichia coli elongation factors Tu and Ts (EF-Tu.Ts) and subsequent mutagenesis work have provided insights into the roles of a number of residues in E. coli EF-Ts in its interaction with EF-Tu. The corresponding residues in bovine mitochondrial EF-Ts (EF-Tsmt) have been mutated. The abilities of the resulting EF-Tsmt derivatives to stimulate the activities of both E. coli and mitochondrial EF-Tu have been tested. Mutation of several residues in EF-Tsmt corresponding to amino acids important for the activity of E. coli EF-Ts has little or no effect on the activity of the mitochondrial factor, suggesting that these factors may use somewhat different mechanisms to promote guanine nucleotide exchange. In general, mutations that reduce the strength of the interaction between EF-Tsmt and E. coli EF-Tu increase the ability of EF-Tsmt to stimulate the activity of the bacterial factor. In contrast, these mutations tend to reduce the ability of EF-Tsmt to stimulate the activity of EF-Tumt. For example, F19A/I20A and H176A derivatives of EF-Tsmt are as active as E. coli EF-Ts in simulating E. coli EF-Tu. However, these mutations significantly decrease the ability of EF-Tsmt to stimulate EF-Tumt.
大肠杆菌延伸因子Tu和Ts（EF-Tu.Ts）复合物的晶体结构以及后续的诱变工作，为深入了解大肠杆菌EF-Ts中多个残基在其与EF-Tu相互作用中的作用提供了线索。牛线粒体EF-Ts（EF-Tsmt）中的相应残基已被诱变。已测试了所得EF-Tsmt衍生物刺激大肠杆菌和线粒体EF-Tu活性的能力。EF-Tsmt中对应于对大肠杆菌EF-Ts活性重要的氨基酸的几个残基发生突变，对线粒体因子的活性几乎没有影响，这表明这些因子可能使用略有不同的机制来促进鸟嘌呤核苷酸交换。一般来说，降低EF-Tsmt与大肠杆菌EF-Tu之间相互作用强度的突变会增加EF-Tsmt刺激细菌因子活性的能力。相反，这些突变往往会降低EF-Tsmt刺激EF-Tumt活性的能力。例如，EF-Tsmt的F19A/I20A和H176A衍生物在模拟大肠杆菌EF-Tu方面与大肠杆菌EF-Ts一样活跃。然而，这些突变显著降低了EF-Tsmt刺激EF-Tumt的能力。
