EFFECT OF RP51 GENE DOSAGE ALTERATIONS ON RIBOSOME SYNTHESIS IN SACCHAROMYCES-CEREVISIAE
EFFECT OF RP51 GENE DOSAGE ALTERATIONS ON RIBOSOME SYNTHESIS IN SACCHAROMYCES-CEREVISIAE
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DOI：
10.1128/mcb.5.12.3429
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发表时间：
1985-01-01
影响因子：
5.3
通讯作者：
ROSBASH, M
中科院分区：
文献类型：
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作者：
ABOVICH, N;GRITZ, L;ROSBASH, M
酿酒酵母核糖体蛋白rp 51由两个可互换的基因RP 51 A和RP 51 B编码。我们通过创建RP 51 A或RP 51 B基因或两者的缺失来改变RP 51基因剂量。这两个基因的缺失导致孢子活力，表明rp 51是一个必不可少的核糖体蛋白。从在单倍体细胞中的单缺失研究，我们得出结论，在mRNA丰度或mRNA利用率（翻译效率）的水平上没有基因间剂量补偿，尽管表型分析先前已经表明对生长速率的小补偿效应。同样，在二倍体菌株中的缺失表明，没有强有力的机制存在基因内剂量补偿;在所有情况下，RP 51基因的剂量减少的特点是生长缓慢的表型。RP 51基因的剂量减少也导致40 S核糖体亚基的量不足，如过量60 S核糖体亚基的急剧积累所证明的。我们的结论是，40 S合成的抑制对60 S亚基组分的合成几乎没有影响。添加额外的rp 51基因拷贝导致额外的rp 51蛋白合成。另外的rp 51蛋白被迅速降解。我们提出，rp 51和可能许多核糖体蛋白通常是过度合成的，但未组装的过量被降解，并且在单倍体中看到的明显补偿，即，突变菌株的生长速率比mRNA的实际减少更少受到抑制的事实是这种过量的结果，在这种情况下，这种过量免于蛋白水解。
The Saccharomyces cerevisiae ribosomal protein rp51 is encoded by two interchangeable genes, RP51A and RP51B. We altered the RP51 gene dose by creating deletions of the RP51A or RP51B genes or both. Deletions of both genes led to spore inviability, indicating that rp51 is an essential ribosomal protein. From single deletion studies in haploid cells, we concluded that there was no intergenic dosage compensation at the level of mRNA abundance or mRNA utilization (translational efficiency), although phenotypic analysis had previously indicated a small compensation effect on growth rate. Similarly, deletions in diploid strains indicated that no strong mechanisms exist for intragenic dosage compensation; in all cases, a decreased dose of RP51 genes was characterized by a slow growth phenotype. A decreased dose of RP51 genes also led to insufficient amounts of 40S ribosomal subunits, as evidenced by a dramatic accumulation of excess 60S ribosomal subunits. We conclude that inhibition of 40S synthesis had little or no effect on the synthesis of the 60S subunit components. Addition of extra copies of rp51 genes led to extra rp51 protein synthesis. The additional rp51 protein was rapidly degraded. We propose that rp51 and perhaps many ribosomal proteins are normally oversynthesized, but the unassembled excess is degraded, and that the apparent compensation seen in haploids, i.e., the fact that the growth rate of mutant strains is less depressed than the actual reduction in mRNA, is a consequence of this excess which is spared from proteolysis under this circumstance.