Yeast ribosomal protein L24 affects the kinetics of protein synthesis and ribosomal protein L39 improves translational accuracy, while mutants lacking both remain viable
Yeast ribosomal protein L24 affects the kinetics of protein synthesis and ribosomal protein L39 improves translational accuracy, while mutants lacking both remain viable
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DOI：
10.1021/bi9925266
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发表时间：
2000-06-20
期刊：
影响因子：
2.9
通讯作者：
Synetos, D
中科院分区：
文献类型：
--
作者：
Dresios, J;Derkatch, IL;Synetos, D
以酿酒酵母的4个突变株为材料，研究了核糖体的结构和功能。它们包括携带编码核糖体蛋白L24的两个基因缺失的菌株、携带核糖体蛋白L39基因中的突变spb2的菌株、携带L39基因缺失的菌株以及缺乏L24和L39的突变体。缺失L24的突变体的多苯丙氨酸合成活性只有正常的25%，而P位点结合活性降低，这表明L24蛋白可能参与了翻译动力学。两个L39突变体的错误频率均比野生型增加了4倍。这伴随着A位点结合的大幅增加，这是易错突变体的典型特征。L39的缺失也增加了对巴龙霉素的敏感性，降低了核糖体亚基比率，并导致了冷敏感表型。缺乏这两种核糖体蛋白的突变细胞仍然存活。它们的核糖体显示出由L24的缺乏引起的初始速率降低，但与野生型相比，聚苯丙氨酸合成的正常程度和80S核糖体的量在体内的大量减少。此外，该突变体显示翻译准确性降低，对抗生素巴龙霉素的超敏反应，以及冷敏感表型，所有这些都主要由L39的缺失引起。蛋白L39是60S核糖体亚基中第一个与翻译准确性有关的蛋白。
Four mutant strains from Saccharomyces cerevisiae were used to study ribosome structure and function. They included a strain carrying deletions of the two genes encoding ribosomal protein L24, a strain carrying a mutation spb2 in the gene for ribosomal protein L39, a strain carrying a deletion of the gene for L39, and a mutant lacking both L24 and L39. The mutant lacking only L24 showed just 25% of the normal polyphenylalanine-synthesizing activity followed by a decrease in P-site binding, suggesting the possibility that protein L24 is involved in the kinetics of translation, Each of the two L39 mutants displayed a 4-fold increase of their error frequencies over the wild type. This was accompanied by a substantial increase in A-site binding, typical of error-prone mutants. The absence of L39 also increased sensitivity to paromomycin, decreased the ribosomal subunit ratio, and caused a cold-sensitive phenotype. Mutant cells lacking both ribosomal proteins remained viable. Their ribosomes showed reduced initial rates caused by the absence of L24 but a normal extent of polyphenylalanine synthesis and a substantial in vivo reduction in the amount of 80S ribosomes compared to wild type. Moreover, this mutant displayed decreased translational accuracy, hypersensitivity to the antibiotic paromomycin, and a cold-sensitive phenotype, all caused mainly by the deletion of L39. Protein L39 is the first protein of the 60S ribosomal subunit implicated in translational accuracy.