A FUNCTIONAL PSEUDOKNOT IN 16S RIBOSOMAL-RNA
A FUNCTIONAL PSEUDOKNOT IN 16S RIBOSOMAL-RNA
复制标题
DOI：
10.1002/j.1460-2075.1991.tb07756.x
复制
发表时间：
1991-08-01
期刊：
影响因子：
11.4
通讯作者：
NOLLER, HF
中科院分区：
文献类型：
--
作者：
POWERS, T;NOLLER, HF
多项证据表明，普遍保守的16S核糖体RNA 530环在翻译中起着至关重要的作用，与tRNA与核糖体a位点的结合有关。基于有限的系统发育序列变异，Woese和Gutell（1989）提出530发卡环中的524-526残基与相邻凸起环中的505-507残基碱基配对，这表明16S rRNA的这一区域折叠成假结结构。在这里，我们证明了这些核苷酸之间的沃森-克里克相互作用对核糖体功能是必不可少的。此外，我们发现结构的某些轻微扰动，例如G-U摆动对的产生，会产生对链霉素的抗性，链霉素是一种已知会干扰解码过程的抗生素。对来自链霉素耐药细胞的突变核糖体的化学探测表明，突变核糖体对链霉素的亲和力降低，尽管链霉素被认为与30S亚基上的一个位点相互作用，而这个位点与530区域不同。来自早期体外组装研究的数据表明，假结结构是由核糖体蛋白S12稳定的，这种突变长期以来被认为会导致链霉素耐药性和依赖性。
Several lines of evidence indicate that the universally conserved 530 loop of 16S ribosomal RNA plays a crucial role in translation, related to the binding of tRNA to the ribosomal A site. Based upon limited phylogenetic sequence variation, Woese and Gutell (1989) have proposed that residues 524-526 in the 530 hairpin loop are base paired with residues 505-507 in an adjoining bulge loop, suggesting that this region of 16S rRNA folds into a pseudoknot structure. Here, we demonstrate that Watson-Crick interactions between these nucleotides are essential for ribosomal function. Moreover, we find that certain mild perturbations of the structure, for example, creation of G-U wobble pairs, generate resistance to streptomycin, an antibiotic known to interfere with the decoding process. Chemical probing of mutant ribosomes from streptomycin-resistant cells shows that the mutant ribosomes have a reduced affinity for streptomycin, even though streptomycin is thought to interact with a site on the 30S subunit that is distinct from the 530 region. Data from earlier in vitro assembly studies suggest that the pseudoknot structure is stabilized by ribosomal protein S12, mutations in which have long been known to confer streptomycin resistance and dependence.