The integrity of the sarcin/ricin domain of 23 S ribosomal RNA is not required for elongation factor-in dependent peptide synthesis
The integrity of the sarcin/ricin domain of 23 S ribosomal RNA is not required for elongation factor-in dependent peptide synthesis
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DOI：
10.1016/j.jmb.2008.02.016
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发表时间：
2008-04-18
影响因子：
5.6
通讯作者：
Wool, Ira G.
中科院分区：
文献类型：
--
作者：
Chan, Yuen-Ling;Wool, Ira G.
蛋白质合成的延伸阶段由氨酰-tRNA结合、肽键形成和易位的重复循环组成。该过程通常由延伸因子Tu和G催化;然而，至少在规定和有限的情况下，在不存在延伸因子的情况下，反应可以进行，这一发现强烈暗示蛋白质合成的化学是核糖体所固有的。23 S rRNA中的sarcin/ricin结构域是核糖体被核糖毒素灭活的位点，是延伸因子结合的地方。出现的问题是是否sarcin/蓖麻毒素结构域是必要的因子独立的肽合成。答案是，并非如此。通过与八叠球菌素或美洲商陆抗病毒蛋白共价修饰的八叠球菌素/蓖麻毒素结构域的破坏不影响因子独立的肽合成;也不影响废除延伸因子结合的核苷酸的致死突变。这些结果表明，唯一的功能的sarcin/蓖麻毒素结构域是提供一个结合位点的延伸因子，因此，以促进延伸反应。这一结果也提出了sarcin/ricin结构域与延伸因子协同进化的可能性。
The elongation stage of protein synthesis consists of repeated cycles of the binding of aminoacyl-tRNA, peptide bond formation, and translocation. The process is normally catalyzed by the elongation factors Tu and G; however, the reactions can proceed, at least in prescribed and limited circumstance, in the absence of the elongation factors, a finding that strongly implies that the chemistry of protein synthesis is inherent in the ribosome. The sarcin/ricin domain in 23 S rRNA, the site of inactivation of ribosomes by ribotoxins, is where the elongation factors bind. The question that arises is whether the sarcin/ricin domain is necessary for factor-independent peptide synthesis. The answer is that it is not. The disruption of the sarcin/ ricin domain by covalent modification with either sarcin or pokeweed antiviral protein did not affect factor-independent peptide synthesis; nor did lethal mutations of nucleotides that abolish the binding of elongation factors. The results imply that the sole function of the sarcin/ricin domain is to provide a binding site for the elongation factors and, hence, to facilitate the elongation reactions. The results also raise the possibility of the co-evolution of the sarcin/ricin domain and the elongation factors.