Deficiency in both type I and type II DNA topoisomerase activities differentially affect rRNA and ribosomal protein synthesis in Schizosaccharomyces pombe.
Deficiency in both type I and type II DNA topoisomerase activities differentially affect rRNA and ribosomal protein synthesis in Schizosaccharomyces pombe.
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I 型和 II 型 DNA 拓扑异构酶活性的缺陷对粟酒裂殖酵母的 rRNA 和核糖体蛋白合成产生不同的影响。
DOI：
10.1007/bf00424424
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发表时间：
1988
期刊：
影响因子：
2.5
通讯作者：
Nomura,M
中科院分区：
文献类型：
--
作者：
Yamagishi,M;Nomura,M
本文研究了裂殖酵母温度敏感型拓扑异构酶突变体中rRNA和R蛋白的合成。为了降低在野生型菌株中观察到的热休克反应的严重性，使用培养物的缓慢温度升高来抑制突变体拓扑异构酶。结果表明，温度的变化导致了top1 top2双突变体rRNA合成的大幅度优先减少。与此相反，没有观察到优先抑制rRNA合成的top1或top2单突变体，虽然在总RNA合成的top2突变体中观察到一些减少。因此，正如在酿酒酵母中所观察到的（Brill等，1987），拓扑异构酶I或II对超螺旋DNA结构的松弛似乎是rRNA基因有效转录所必需的。R-蛋白合成分析表明，温度升高后，top1 top2突变体的R-蛋白差异合成速率略有下降，但对R-蛋白合成的负面影响远小于对rRNA合成的负面影响，并观察到新合成的R-蛋白的降解。这些观察结果表明，在这些实验条件下，在粟酒裂殖酵母中rRNA和r-蛋白合成之间明显缺乏紧密偶联。
The synthesis of rRNA and r-proteins was studied in temperature-sensitive topoisomerase mutants of the fisson yeastSchizosaccharomyces pombe. To reduce the severity of heatshock response seen in the wild type strain, slow temperature shift-up of the cultures was used to inactivate the mutant topoisomerases. It was found that the temperature shift caused a large preferential reduction of rRNA synthesis in thetop1top2double mutant. In contrast, no preferential inhibition of rRNA synthesis was observed intop1ortop2single mutants, although some reduction in the total RNA synthesis was observed in thetop2mutant. Thus, as observed withSaccharomyces cerevisiae(Brill et al. 1987), relaxation of supercoiled DNA structures by either topoisomerase I or II appears to be essential for efficient transcription of rRNA genes. Analysis of r-protein synthesis indicated that there were small decreases in the differential synthesis rates of r-proteins after temperature shift-up in thetop1top2mutant, but the observed negative effects on r-protein synthesis was much smaller than that on rRNA synthesis, and degradation of the newly synthesized r-proteins was observed. These observations indicate the apparent lack of tight coupling between rRNA and r-protein synthesis inS. pombeunder these experimental conditions.