CONTROL OF TRANSLATIONAL REPRESSION BY PROTEIN - PROTEIN INTERACTIONS
CONTROL OF TRANSLATIONAL REPRESSION BY PROTEIN - PROTEIN INTERACTIONS
复制标题
DOI：
10.1093/nar/20.7.1649
复制
发表时间：
1992-04-11
影响因子：
14.9
通讯作者：
ELY, KR
中科院分区：
文献类型：
--
作者：
PEABODY, DS;ELY, KR
RNA噬菌体MS 2的外壳蛋白是一种翻译阻遏物，与特定的RNA茎环相互作用以抑制病毒复制酶基因的翻译。作为从遗传学上剖析其RNA结合功能的努力的一部分，在外壳蛋白序列中鉴定了抑制翻译操纵子中突变缺陷的突变。每一个突变体都表现出一个超级阻遏物表型，抑制野生型和各种突变操作员的翻译比野生型外壳蛋白。至少有一个突变体可能比野生型更紧密地结合RNA。然而，其他的突变体，是有缺陷的病毒样颗粒的装配，并自我相关的二聚体为主。有人提出，这种组装缺陷占他们的超级阻遏物的特点，因为未能组装成病毒样颗粒提高了有效浓度的阻遏物二聚体。这一假设得到以下观察结果的支持：已知对二聚体组装成衣壳重要的13个氨基酸的缺失也导致相同的组装缺陷和超阻遏物活性。还描述了第二类装配缺陷。从外壳蛋白的C-末端缺失两个氨基酸导致未能形成衣壳，大多数外壳蛋白具有预期的三聚体的表观分子量。这种突变体（dI-8）是完全有缺陷的阻遏活性，可能是因为无法形成二聚体。这些结果表明外壳蛋白的结构和调节功能是相互依赖的。
The coat protein of the RNA bacteriophage MS2 is a translational repressor and interacts with a specific RNA stem-loop to inhibit translation of the viral replicase gene. As part of an effort to dissect genetically its RNA binding function, mutations were identified in the coat protein sequence that suppress mutational defects in the translational operator. Each of the mutants displayed a super-repressor phenotype, repressing translation from the wild-type and a variety of mutant operators better than did the wild-type coat protein. At least one mutant probably binds RNA more tightly than wild-type. The other mutants, however, were defective for assembly of virus-like particles, and self-associated predominantly as dimers. It is proposed that this assembly defect accounts for their super-repressor characteristics, since failure to assemble into virus-like particles elevates the effective concentration of repressor dimers. This hypothesis is supported by the observation that deletion of thirteen amino acids known to be important for assembly of dimers into capsids also resulted in the same assembly defect and in super-repressor activity. A second class of assembly defects is also described. Deletion of two amino acids from the C-terminus of coat protein resulted in failure to form capsids, most of the coat protein having the apparent molecular weight expected of trimers. This mutant (dI-8) was completely defective for repressor activity, probably because of an inability to form dimers. These resuLts point out the inter-dependence of the structural and regulatory functions of coat protein.