Ramakrishnan V, White S W
Biology Department, Brookhaven National Laboratory, Upton, New York 11973.
Nature. 1992 Aug 27;358(6389):768-71. doi: 10.1038/358768a0.
Understanding the process whereby the ribosome translates the genetic code into protein molecules will ultimately require high-resolution structural information, and we report here the first crystal structure of a protein from the small ribosomal subunit. This protein, S5, has a molecular mass of 17,500 and is highly conserved in all lifeforms. The molecule contains two distinct alpha/beta domains that have structural similarities to several other proteins that are components of ribonucleoprotein complexes. Mutations in S5 result in several phenotypes which suggest that S5 may have a role in translational fidelity and translocation. These include ribosome ambiguity or ram, reversion from streptomycin dependence and resistance to spectinomycin. Also, a cold-sensitive, spectinomycin-resistant mutant of S5 has been identified which is defective in initiation. Here we show that these mutations map to two distinct regions of the molecule which seem to be sites of interaction with ribosomal RNA. A structure/function analysis of the molecule reveals discrepancies with current models of the 30S subunit.
要最终理解核糖体将遗传密码翻译成蛋白质分子的过程，需要高分辨率的结构信息，我们在此报告小核糖体亚基中一种蛋白质的首个晶体结构。这种蛋白质S5分子量为17500，在所有生命形式中高度保守。该分子包含两个不同的α/β结构域，它们与核糖核蛋白复合物的其他几种蛋白质成分在结构上具有相似性。S5中的突变会导致多种表型，这表明S5可能在翻译保真度和易位中发挥作用。这些表型包括核糖体模糊性或ram、从链霉素依赖性回复以及对壮观霉素的抗性。此外，已鉴定出一种对壮观霉素耐药的S5冷敏感突变体，其起始过程存在缺陷。我们在此表明，这些突变定位于分子的两个不同区域，这两个区域似乎是与核糖体RNA相互作用的位点。对该分子的结构/功能分析揭示了与当前30S亚基模型的差异。
