核糖体蛋白的突变S4和S12影响16 S rrna的高阶结构。
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艾伦PN, nol高频
核糖体蛋白的突变S4和S12影响16 S rrna的高阶结构。
J杂志。1989年8月5日,208 (3):457 - 68。
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2477554 (在PubMed]
- 文摘
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我们研究了蛋白质突变的影响16 S rRNA的高阶结构在大肠杆菌核糖体,使用一组structure-sensitive化学探测器。十个突变株进行了研究,包含S4的核糖体蛋白的变更和S12,包括包含改变S4和S12双突变体。两个核糖体模棱两可(ram) S4突变株,四个链霉素耐药鼻中隔黏膜下切除术后()S12突变株,一个链霉素pseudodependent (SmP) S12突变株,依赖一个链霉素(SmD) S12突变株和两个独立链霉素(Sm1)双突变体(包含both-SmD和ram突变)探测,而同基因的野生型菌株。在核糖体从包含S4 ram突变菌株,核苷酸A8和A26变得更被动的硫酸二甲酯(DMS) n - 1的位置。核糖体的压力轴承SmD等位基因,A908, A909, A1413 G1487活性明显下降。化学探测器。这些影响是观察当S4和S12突变双突变体中同时存在。发现一个有趣的相关性之间的反应性A908和密码错编的潜力,SmD, SmP和野生型核糖体;A908反应的增加作为核糖体的平移误差的频率增加。在ram中核糖体,A908类似于野生型的反应,除非tRNA绑定,在这种情况下,它变得hyper-reactive。同样,在野生型核糖体A908链霉素几乎没有影响,除非tRNA是有限的,在这种情况下,其反应性增加类似于ram和绑定tRNA核糖体。 Finally, interaction of streptomycin with SmP and SmD ribosomes causes the reactivity of A908 to increase to near-wild-type levels. A simple model is proposed, in which the reactivity of A908 reflects the position of an equilibrium between two conformational states of the 30 S subunit, one of which is DMS-reactive, and the other DMS-unreactive. In this model, the balance between these two states would be influenced by proteins S4 and S12. Mutations in S12 generally cause a shift toward the unreactive conformer, and in the case of SmD and SmP ribosomes, this shift can be suppressed phenotypically by streptomycin, ram mutations in protein S4 cause a shift toward the reactive conformer, but only when tRNA is bound. This suggests that the opposing effects of these two classes of mutations influence the proof-reading process by somewhat different mechanisms.