Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos (UAEM), Cuernavaca, Morelos, México.
J Basic Microbiol. 2013 Apr;53(4):365-80. doi: 10.1002/jobm.201100525. Epub 2012 Aug 23.
Adenosine-5-triphosphate (ATP) plays a fundamental role in many cellular processes such as transport, central carbon metabolism, biosynthetic reactions, macromolecular synthesis, signal transduction and cellular division. In addition, the intracellular [ATP]/[ADP] ratio in Escherichia coli plays an important role in controlling the specific rates of growth (µ), glucose consumption (qGlc ) and oxygen uptake (qO2), as well as the transcriptome pattern in the cell, as was recently reported. In the current study, the energetic level (expressed as [ATP]/[ADP] ratio) was substantially reduced in E. coli strains by either over-expressing the F1 -ATPase activity (JMAGD(+)) or inactivating ATP synthase (JMat(-)). The physiological characterization of the wild-type JM101 strain and its derivative JMAGD(+) and JMatp(-) strains was conducted in bioreactors containing minimal medium with glucose. The inactivation of the atp operon and F1 -ATPase overexpression significantly diminished the energetic level and cAMP concentration in derivative strains. Relative transcription levels of 105 genes involved in glucose transport, glycolysis, tricarboxylic acid (TCA) cycle, fermentation, respiration, transcriptional regulators, transcription and genes involved in stress were determined by using qPCR. Interestingly, in the JMAGD(+) and JMatp(-) strains, having a reduced energetic level, many transcripts of glycolysis, TCA cycle and respiratory genes were down-regulated when compared to wild type JM101. The transcriptional responses, detected in the strains with reduced energetic level show down-regulation of genes involved in central carbon metabolism and respiration, these results are apposite to the observed trends of increased metabolic fluxes in glucose consumption, glycolysis, acetate synthesis, TCA cycle and respiration. Regulation mediated by CRP-cAMP complex may explain some observed transcriptional responses of TCA cycle genes, since cAMP concentration and crp transcript level were significant reduced in the JMatp(-) mutant. Therefore, the substantial reduction of [ATP]/[ADP] ratio had a relevant effect on the CRP-cAMP regulatory system (among other global regulators), which may trigger an extensive transcriptional response.
三磷酸腺苷（ATP）在许多细胞过程中发挥着基本作用，如运输、中心碳代谢、生物合成反应、大分子合成、信号转导和细胞分裂。此外，最近有报道称，大肠杆菌细胞内的[ATP]/[ADP]比值在控制特定生长速率（µ）、葡萄糖消耗（qGlc）和耗氧量（qO2）以及细胞转录组模式方面起着重要作用。在本研究中，通过过度表达 F1-ATP 酶活性（JMAGD(+))或使 ATP 合酶失活（JMat(-))，大肠杆菌菌株的能量水平（用[ATP]/[ADP]比值表示）显著降低。在含有葡萄糖的最小培养基的生物反应器中对野生型 JM101 菌株及其衍生 JMAGD(+)和 JMatp(-)菌株进行了生理特性分析。atp 操纵子失活和 F1-ATP 酶过表达显著降低了衍生菌株的能量水平和 cAMP 浓度。通过 qPCR 测定了 105 个与葡萄糖转运、糖酵解、三羧酸（TCA）循环、发酵、呼吸、转录调节因子、转录和应激相关基因相关的相对转录水平。有趣的是，在 JMAGD(+)和 JMatp(-)菌株中，由于能量水平降低，与野生型 JM101 相比，许多糖酵解、TCA 循环和呼吸基因的转录物下调。在能量水平降低的菌株中检测到的转录反应显示，参与中心碳代谢和呼吸的基因下调，这些结果与观察到的葡萄糖消耗、糖酵解、乙酸合成、TCA 循环和呼吸代谢通量增加的趋势相符。由 CRP-cAMP 复合物介导的调节可能解释了 TCA 循环基因观察到的一些转录反应，因为 cAMP 浓度和 crp 转录物水平在 JMatp(-)突变体中显著降低。因此，[ATP]/[ADP]比值的显著降低对 CRP-cAMP 调节系统（以及其他全局调节剂）产生了相关影响，这可能引发广泛的转录反应。
