Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.
mBio. 2019 Jan 22;10(1):e02500-18. doi: 10.1128/mBio.02500-18.
Correlations between gene transcription and the abundance of high-energy purine nucleotides in have often been noted. However, there has been no systematic investigation of this phenomenon in the absence of confounding factors such as nutrient status and growth rate, and there is little hard evidence for a causal relationship. Whether transcription is fundamentally responsive to prevailing cellular energetic conditions via sensing of intracellular purine nucleotides, independently of specific nutrition, remains an important question. The controlled nutritional environment of chemostat culture revealed a strong correlation between ATP and GTP abundance and the transcription of genes required for growth. Short pathways for the inducible and futile consumption of ATP or GTP were engineered into , permitting analysis of the transcriptional effect of an increased demand for these nucleotides. During steady-state growth using the fermentable carbon source glucose, the futile consumption of ATP led to a decrease in intracellular ATP concentration but an increase in GTP and the guanylate energy charge (GEC). Expression of transcripts encoding proteins involved in ribosome biogenesis, and those controlled by promoters subject to SWI/SNF-dependent chromatin remodelling, was correlated with these nucleotide pool changes. Similar nucleotide abundance changes were observed using a nonfermentable carbon source, but an effect on the growth-associated transcriptional programme was absent. Induction of the GTP-cycling pathway had only marginal effects on nucleotide abundance and gene transcription. The transcriptional response of respiring cells to glucose was dampened in chemostats induced for ATP cycling, but not GTP cycling, and this was primarily associated with altered adenine nucleotide levels. This paper investigates whether, independently of the supply of any specific nutrient, gene transcription responds to the energy status of the cell by monitoring ATP and GTP levels. Short pathways for the inducible and futile consumption of ATP or GTP were engineered into the yeast , and the effect of an increased demand for these purine nucleotides on gene transcription was analyzed. The resulting changes in transcription were most consistently associated with changes in GTP and GEC levels, although the reprogramming in gene expression during glucose repression is sensitive to adenine nucleotide levels. The results show that GTP levels play a central role in determining how genes act to respond to changes in energy supply and that any comprehensive understanding of the control of eukaryotic gene expression requires the elucidation of how changes in guanine nucleotide abundance are sensed and transduced to alter the global pattern of transcription.
已有研究常注意到基因转录与高能嘌呤核苷酸丰度之间存在相关性。然而，在没有营养状态和生长速率等混杂因素的情况下，尚未对这一现象进行系统研究，也几乎没有确凿证据表明存在因果关系。转录是否通过感应细胞内嘌呤核苷酸而从根本上对细胞能量状态做出响应，而不依赖于特定的营养物质，这仍然是一个重要的问题。恒化器培养所提供的受控营养环境揭示了 ATP 和 GTP 丰度与生长所需基因转录之间存在很强的相关性。构建了可诱导和无效消耗 ATP 或 GTP 的短代谢途径，以此分析对这些核苷酸需求增加的转录效应。在使用可发酵碳源葡萄糖进行稳态生长时，无效消耗 ATP 导致细胞内 ATP 浓度降低，但 GTP 和鸟苷酸能量电荷（GEC）增加。编码核糖体生物发生相关蛋白的转录本以及受 SWI/SNF 依赖性染色质重塑调控的转录本的表达与这些核苷酸池变化相关。使用不可发酵碳源时观察到类似的核苷酸丰度变化，但对与生长相关的转录程序没有影响。GTP 循环途径的诱导对核苷酸丰度和基因转录的影响很小。在葡萄糖诱导的 ATP 循环而不是 GTP 循环恒化器中，呼吸细胞对葡萄糖的转录响应被减弱，这主要与腺嘌呤核苷酸水平的改变有关。本文研究了在不供应任何特定营养素的情况下，细胞是否通过监测 ATP 和 GTP 水平来响应细胞的能量状态，从而调节基因转录。在酵母中构建了可诱导和无效消耗 ATP 或 GTP 的短代谢途径，并分析了这些嘌呤核苷酸需求增加对基因转录的影响。转录的变化与 GTP 和 GEC 水平的变化最一致，尽管在葡萄糖抑制期间基因表达的重新编程对腺嘌呤核苷酸水平敏感。结果表明，GTP 水平在确定基因如何响应能量供应变化方面起着核心作用，任何对真核基因表达控制的全面理解都需要阐明如何感知和转导鸟嘌呤核苷酸丰度的变化，以改变全局转录模式。
