Stringent control of bacterial transcription
Stringent control of bacterial transcription
复制标题
严格控制细菌转录
DOI：
10.1016/0092-8674(85)90050-9
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发表时间：
1985
期刊：
影响因子：
64.5
通讯作者：
A. Travers
中科院分区：
文献类型：
--
作者：
A. Lamond;A. Travers
当细菌细胞经历由氨基酸的有限可用性或其主要碳源耗尽引起的饥饿时，它们停止进一步生长，并对其代谢进行快速，复杂和多样的调整。许多不同代谢过程的速率，包括RNA的积累、DNA的复制、碳水化合物、脂质、核苷酸、肽聚糖和糖酵解中间体的生物合成，都降低，细胞内蛋白水解的总速率增加，并且许多大分子前体穿过细胞膜的运输受到抑制。这种调节范围，已知氨基酸饥饿作为严格的反应，共同提高了细菌在营养缺乏期间的生存力，重要的是，当环境条件改善时，允许快速恢复和重新启动生长。在快速生长的细菌中，核糖体的合成需要大部分的可用能量。因此，响应于饥饿和其他环境损害而停止该过程构成了能量保存的重要模式。核糖体生物合成速率的突然变化是由于核糖体蛋白的稳定RNA（即rRNA、tRNA）和mRNA的合成受到高度特异性的抑制，这些基因的转录速率下降了约10倍。相比之下，总mRNA合成的速率在饥饿后仅适度降低，而某些物种的总mRNA合成的速率，例如His mRNA（Stephens et al.，PNAS 72，4389-4393，1975），实际上被刺激。在这些观察中隐含的是E。大肠杆菌细胞可以选择性地调节编码翻译器各组成部分的基因，其机制有多种：转录起始的控制、RNA链延长的阻滞（聚合酶暂停）、甚至新生稳定RNA的更新。虽然现在的证据表明，转录起始的调制是主要的控制，其他机制的贡献作用尚未被排除。
When bacterial cells experience starvation caused by limited availability of amino acids or by exhaustion of their primary carbon source, they halt further growth and make a rapid, complex, and varied set of adjustments to their metabolism. The rates of many disparate metabolic processes, including the accumulation of RNA, the replication of DNA, the biosynthesis of carbohydrates, lipids, nucleotides, peptidoglycans, and glycolytic intermediates, are all reduced, the total rate of intracellular proteolysis is increased, and the transport of many macromolecular precursors across the ceil membrane is inhibited. This spectrum of regulation, known for amino acid starvation as the stringent response, collectively enhances the viability of bacteria during periods of nutritional deprivation and, importantly, allows quick recovery and reinitiation of growth when the environmental conditions improve. In a rapidly growing bacterium, a major proportion of the available energy is required for the synthesis of ribosomes. Thus, cessation of this process in response to starvation and other environmental insults constitutes an important mode of energy conservation. The abrupt change in the rate of ribosome biosynthesis results from a highly specific inhibition of the synthesis of stable RNAs (ie, rRNA, tRNA) and mRNA for ribosomal proteins, the transcription rate of these genes falling by some lo-fold. By contrast, the rate of total mRNA synthesis is only modestly reduced after starvation, while that of certain species, such as his mRNA (Stephens et al., PNAS 72, 4389-4393, 1975), is actually stimulated. What is implicit in these observations is that E. coli cells can selectively regulate the genes encoding the components of the translational apparatus.A plethora of mechanisms have been proposed to explain this selective regulation: control of transcription initiation, arrest of RNA chain elongation(polymerase pausing), and even an increased turnover of nascent stable RNA. Although the evidence now shows that modulation of transcription initiation is the principal control, a contributory role for other mechanisms has not been excluded.