Brock S, Szkaradkiewicz K, Sprinzl M
Laboratorium für Biochemie, Universität Bayreuth, Germany.
Mol Microbiol. 1998 Jul;29(2):409-17. doi: 10.1046/j.1365-2958.1998.00893.x.
Initiation of protein biosynthesis in bacteria requires three initiation factors: initiation factor 1, initiation factor 2 and initiation factor 3. The mechanism by which initiation factors form the 70S initiation complex with initiator fMet-tRNA(fMet) interacting with the initiation codon in the ribosomal P site and the second mRNA codon exposed in the A site is not yet understood. Here, we present a model for the function of initiation factors 1 and 2 that is based on the analysis of sequence homologies, biochemical evidence and the present knowledge of the three-dimensional structures of translation factors and ribosomes. The model predicts that initiation factors 1 and 2 interact with the ribosomal A site mimicking the structure of the elongation factor G. We present data that extend the mimicry hypothesis to initiation factors 1 and 2, originally postulated for the aminoacyl-tRNA x elongation factor Tu x GTP ternary complex, elongation factor G and release factors.
起始因子1、起始因子2和起始因子3。起始因子与起始fMet - tRNA（fMet）形成70S起始复合物，该起始fMet - tRNA（fMet）与核糖体P位点的起始密码子以及A位点暴露的第二个mRNA密码子相互作用，其机制尚不清楚。在此，我们基于对序列同源性、生化证据以及翻译因子和核糖体三维结构的现有知识的分析，提出了一个关于起始因子1和2功能的模型。该模型预测，起始因子1和2与核糖体A位点相互作用，模拟延伸因子G的结构。我们提供的数据将模拟假说扩展到起始因子1和2，该假说最初是针对氨酰 - tRNA·延伸因子Tu·GTP三元复合物、延伸因子G和释放因子提出的。
