Transcriptional and Metabolic Response of a Strain of PTS to a Perturbation of the Energetic Level by Modification of [ATP]/[ADP] Ratio.

The intracellular [ATP]/[ADP] ratio is crucial for 's cellular functions, impacting transport, phosphorylation, signaling, and stress responses. Overexpression of F-ATPase genes in increases glucose consumption, lowers energy levels, and triggers transcriptional responses in central carbon metabolism genes, particularly glycolytic ones, enhancing carbon flux. In this contribution, we report the impact of the perturbation of the energetic level in a PTS mutant of by modifying the [ATP]/[ADP] ratio by uncoupling the cytoplasmic activity of the F subunit of the ATP synthase. The disruption of [ATP]/[ADP] ratio in the evolved strain of PB12 (PTS) was achieved by the expression of the operon encoding the soluble portion of ATP synthase F-ATPase (strain PB12AGD). The analysis of the physiological and metabolic response of the PTS strain to the ATP disruption was determined using RT-qPCR of 96 genes involved in glucose and acetate transport, glycolysis and gluconeogenesis, pentose phosphate pathway (PPP), TCA cycle and glyoxylate shunt, several anaplerotic, respiratory chain, and fermentative pathways genes, sigma factors, and global regulators. The mutant exhibited reduced growth despite increased glucose transport due to decreased energy levels. It heightened stress response capabilities under glucose-induced energetic starvation, suggesting that the carbon flux from glycolysis is distributed toward the pentose phosphate and the Entner-Duodoroff pathway with the concomitant. Increase acetate transport, production, and utilization in response to the reduction in the [ATP]/[ADP] ratio. Upregulation of several genes encoding the TCA cycle and the glyoxylate shunt as several respiratory genes indicates increased respiratory capabilities, coupled possibly with increased availability of electron donor compounds from the TCA cycle, as this mutant increased respiratory capability by 240% more than in the PB12. The reduction in the intracellular concentration of cAMP in the mutant resulted in a reduced number of upregulated genes compared to PB12, suggesting that the mutant remains a robust genetic background despite the severe disruption in its energetic level.