Marr A G
Department of Microbiology, University of California, Davis 95616.
Microbiol Rev. 1991 Jun;55(2):316-33. doi: 10.1128/mr.55.2.316-333.1991.
It should be possible to predict the rate of growth of Escherichia coli of a given genotype in a specified environment. The idea that the rate of synthesis of ATP determines the rate of growth and that the yield of ATP determines the yield of growth is entrenched in bacterial physiology, yet this idea is inconsistent with experimental results. In minimal media the growth rate and yield vary with the carbon source in a manner independent of the rate of formation and yield of ATP. With acetate as the carbon source, anapleurotic reactions, not ATP synthesis, limit the growth rate. For acetate and other gluconeogenic substrates the limiting step appears to be the formation of triose phosphate. I conclude that the rate of growth is controlled by the rate of formation of a precursor metabolite and, thus, of monomers such as amino acids derived from it. The protein-synthesizing system is regulated according to demand for protein synthesis. I examine the conjecture that the signal for this regulation is the ratio of uncharged tRNA to aminoacyl-tRNA, that this signal controls the concentration of guanosine tetraphosphate, and that the concentration of guanosine tetraphosphate controls transcription of rrn genes. Differential equations describing this system were solved numerically for steady states of growth; the computed values of ribosomes and guanosine tetraphosphate and the maximal growth rate agree with experimental values obtained from the literature of the past 35 years. These equations were also solved for dynamical states corresponding to nutritional shifts up and down.
应该能够预测给定基因型的大肠杆菌在特定环境中的生长速率。ATP的合成速率决定生长速率，ATP的产量决定生长产量这一观点在细菌生理学中根深蒂固，但这一观点与实验结果不一致。在基本培养基中，生长速率和产量随碳源的变化方式与ATP的形成速率和产量无关。以乙酸盐作为碳源时，回补反应而非ATP合成限制了生长速率。对于乙酸盐和其他糖异生底物，限速步骤似乎是磷酸丙糖的形成。我的结论是，生长速率受前体代谢物的形成速率控制，进而受由此衍生的单体（如氨基酸）的形成速率控制。蛋白质合成系统根据对蛋白质合成的需求进行调节。我研究了这样一种推测：这种调节的信号是未负载tRNA与氨酰tRNA的比例，该信号控制四磷酸鸟苷的浓度，且四磷酸鸟苷的浓度控制rrn基因的转录。针对生长的稳态，对描述该系统的微分方程进行了数值求解；核糖体、四磷酸鸟苷的计算值以及最大生长速率与过去35年文献中获得的实验值相符。还针对营养物质上调和下调对应的动态状态求解了这些方程。
