Project description:Widely reported discrepancies between metabolic flux and transcripts or enzyme levels in bacterial metabolism imply complex regulation mechanisms need to be considered, especially in new bacterial platforms for bioremediation and bioproduction. Comamonas testosteroni strains, which metabolize various natural and xenobiotic aromatic compounds, represent such platforms whose metabolic regulations are still unknown. Here, we identify analogous multi-level regulation mechanisms in the metabolism of two lignin-related (4-hydroxybenzoate and vanillate) and one plastic-related (terephthalate) aromatic compounds in C. testosteroni KF-1, a wastewater isolate. Transcription-level regulation controlled initial catabolism and cleavage of the compounds, but subsequent carbon fluxes in central carbon metabolism are governed by metabolite-level thermodynamic regulation. Quantitative 13C-fingerprinting of tricarboxylic acid cycle and cataplerotic reactions elucidate key carbon routing that is not evident from enzyme abundance changes. Therefore, as-needed transcriptional activation of aromatic catabolism is coupled with metabolic fine-tuning of central metabolism, thus delineating pathway candidates for different metabolic manipulations.
