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首页> 外文期刊>Journal of bacteriology >Effect of Temperature on In Vivo Protein Synthetic Capacity in Escherichia coli
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Effect of Temperature on In Vivo Protein Synthetic Capacity in Escherichia coli

机译：温度对大肠杆菌体内蛋白质合成能力的影响

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In this report, we examine the effect of temperature on protein synthesis. The rate of protein accumulation is determined by three factors: the number of working ribosomes, the rate at which ribosomes are working, and the rate of protein degradation. Measurements of RNA/protein ratios and the levels of individual ribosomal proteins and rRNA show that the cellular amount of ribosomal machinery in Escherichia coli is constant between 25 and 37°C. Within this range, in a given medium, temperature affects ribosomal function the same as it affects overall growth. Two independent methodologies show that the peptide chain elongation rate increases as a function of temperature identically to growth rate up to 37°C. Unlike the growth rate, however, the elongation rate continues to increase up to 44°C at the same rate as between 25 and 37°C. Our results show that the peptide elongation rate is not rate limiting for growth at high temperature. Taking into consideration the number of ribosomes per unit of cell mass, there is an apparent excess of protein synthetic capacity in these cells, indicating a dramatic increase in protein degradation at high temperature. Temperature shift experiments show that peptide chain elongation rate increases immediately, which supports a mechanism of heat shock response induction in which an increase in unfolded, newly translated protein induces this response. In addition, we find that at low temperature (15°C), cells contain a pool of nontranslating ribosomes which do not contribute to cell growth, supporting the idea that there is a defect in initiation at low temperature.
机译：在这份报告中，我们研究了温度对蛋白质合成的影响。蛋白质积累的速率取决于三个因素：有效核糖体的数量，核糖体起作用的速率以及蛋白质降解的速率。对RNA /蛋白质比率以及单个核糖体蛋白质和rRNA水平的测量表明，大肠杆菌中核糖体机制的细胞数量在25至37°C之间恒定。在此范围内，在给定的培养基中，温度影响核糖体功能的程度与其影响总体生长的程度相同。两种独立的方法学表明，肽链的延伸率随着温度的升高而增加，与直至37°C的生长速度相同。但是，与增长率不同，伸长率以与25到37°C相同的速率持续增加到44°C。我们的结果表明，肽的延伸速率不受高温下生长速率的限制。考虑到每单位细胞质量的核糖体数量，这些细胞中蛋白质合成能力明显过剩，表明高温下蛋白质降解显着增加。温度变化实验表明，肽链的延伸率立即增加，这支持了热休克反应诱导的机制，其中未折叠的新翻译蛋白质的增加诱导了这种反应。此外，我们发现在低温（15°C）下，细胞中含有非翻译核糖体池，这些核糖体对细胞的生长没有贡献，这支持了低温启动存在缺陷的想法。

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