Dissociation rates of peptidyl-tRNA from the P-site of E-coli ribosomes
Dissociation rates of peptidyl-tRNA from the P-site of E-coli ribosomes
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DOI：
10.1002/j.1460-2075.1996.tb00453.x
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发表时间：
1996-03-01
期刊：
影响因子：
11.4
通讯作者：
Ehrenberg, M
中科院分区：
文献类型：
--
作者：
Karimi, R;Ehrenberg, M
我们研究了多(U)编程野生型大肠杆菌核糖体p位点上肽基trna的解离率，S12中改变的高精度变体（SmD, SmP）和S4或S5中改变的易出错变体（Ram）。实验在链霉素存在和不存在的情况下进行，并在野生型核糖体中测试新霉素的作用。肽基trna与野生型核糖体p位点的结合比与a位点的结合强得多。添加链霉素显著降低了其对p位点的亲和力，S12的改变使肽基trna的p位点结合更加紧密，而S4、S5的改变使其与野生型的结合更弱。我们发现，当肽基trna与a位点结合较弱时，对p位点的亲和力较强，反之亦然。根据这些结果，我们提出了基于16S rRNA三级结构变形的链霉素和新霉素作用的假设。这些结果也被用来解释一些关于翻译过程的体内实验。
We studied the dissociation rates of peptidyl-tRNA from the P-site of poly(U)-programmed wild-type Escherichia coli ribosomes, hyperaccurate variants altered in S12 (SmD, SmP) and error-prone variants (Ram) altered in S4 or S5. The experiments were carried out in the presence and absence of streptomycin, and the effects of neomycin were tested in the wild-type ribosomes. Binding of peptidyl-tRNA to the P-site of wild-type ribosomes is much stronger than to their A-site. Addition of streptomycin dramatically reduces its affinity for the P-site, The S12 alterations make the P-site binding of peptidyl-tRNA much tighter, and the S4, S5 alterations make it weaker than in the case of the wild-type. We find that when binding of peptidyl-tRNA to the A-site is weak, then the affinity for the P-site is stronger, and vice versa, From these results, we formulate a hypothesis for the actions of streptomycin and neomycin based on deformations of the 16S rRNA tertiary structure. The results are also used to interpret some in vivo experiments on translational processivity.