We observed that the whole atp operon was down-regulated, supporting the fact that energy generation pathway are repressed during metabolic stress.
Hence, it became apparent that a significant number of genes involved in the energy generation pathway, and in particular OXPHOS, not only share the same metabolic pathway (ATP synthesis) and interact at a protein-level, but also share tight co-expression at the mRNA level within and across different conditions and organisms.
The rate limiting steps of both glycolysis as well as TCA cycle were down-regulated which would result in retarded substrate utilization and energy generation pathways.
We observed that in all the three cases, the genes associated with metabolic activity in terms of carbon utilization and energy generation pathways were severely down-regulated.
Simultaneously the carbon utilization and energy generation pathways starting from Glycolysis, TCA to electron transport chain were severely repressed resulting in decreased growth yield, product formation and viability of the cell population as has been shown by Hardiman et al. (2007).
This included the major channels of precursor molecules like transporters (artJ, mglB, hisJ, ybeJ, ptsH, sufC, ycdO, gatA, gatB, gatC, fepA, ompA, actP and mrdB), central intermediary metabolism (pdhR, aceE, aceF, lpdA, and gltA), amino acid metabolism (argE, argH, entA, entB, entE, entF, aspA and ubiF) and energy generation pathways genes which were down-regulated.
These genes are representative of the photosynthetic and Ci fixation, nitrogen metabolism and energy generation pathways.
Further, these processes did not exhibit a transcriptional repression in barley roots indicating that energy generation pathways are more sensitive to salt stress in rice than barley.
During mid larval development queen larvae have higher expression of genes involved in energy generation pathways, including the tricarboxylic acid cycle (TCA) and oxidative phosphorylation.
This ability to utilize diverse inputs and energy generation pathways stands in stark contrast to the metabolic capabilities of Buchnera, which lacks a functional TCA cycle, relying on its host for inputs for oxidative phosphorylation.
It has been reported that in S. pneumoniae concerted action of lactate oxidase and pyruvate oxidase forms a novel energy-generation pathway by converting lactate acid to acetic acid under aerobic growth conditions [ 81].
