Tuning the affinity of aminoacyl-tRNA to elongation factor Tu for optimal decoding
Tuning the affinity of aminoacyl-tRNA to elongation factor Tu for optimal decoding
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DOI：
10.1073/pnas.1102128108
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发表时间：
2011-03-29
影响因子：
11.1
通讯作者：
Uhlenbeck, Olke C.
中科院分区：
文献类型：
--
作者：
Schrader, Jared M.;Chapman, Stephen J.;Uhlenbeck, Olke C.
为了更好地理解为什么氨基酰基tRNAs （aa-tRNAs）已经进化到以统一的亲和力结合细菌延伸因子Tu (EF-Tu)，研究人员检测了对EF-Tu具有不同亲和力的突变tRNAs在大肠杆菌核糖体上的解码。在饱和的EF-Tu浓度下，弱结合的aa- trna与野生型trna相似，可以解码其同源密码子。然而，结合更紧密的aa- trna由于EF-Tu中心dot GDP的缓慢释放而显示出肽键形成率降低。因此，aa- trna对EF-Tu的亲和力被限制为均匀的，因为它们需要足够紧密地结合以形成三元配合物，但在解码过程中足够弱地从EF-Tu释放。与现有的晶体结构一致，酯化氨基酸的身份和tRNA T茎中的三个碱基对结合起来确定了每个aa-tRNA对EF-Tu的亲和力，无论是在核糖体上还是在核糖体上。
To better understand why aminoacyl-tRNAs (aa-tRNAs) have evolved to bind bacterial elongation factor Tu (EF-Tu) with uniform affinities, mutant tRNAs with differing affinities for EF-Tu were assayed for decoding on Escherichia coli ribosomes. At saturating EF-Tu concentrations, weaker-binding aa-tRNAs decode their cognate codons similarly to wild-type tRNAs. However, tighter-binding aa-tRNAs show reduced rates of peptide bond formation due to slow release from EF-Tu center dot GDP. Thus, the affinities of aa-tRNAs for EF-Tu are constrained to be uniform by their need to bind tightly enough to form the ternary complex but weakly enough to release from EF-Tu during decoding. Consistent with available crystal structures, the identity of the esterified amino acid and three base pairs in the T stem of tRNA combine to define the affinity of each aa-tRNA for EF-Tu, both off and on the ribosome.