What are the signals that control catabolite repression in Pseudomonas?

Abstract

Metabolically versatile bacteria exhibit a global regulatory response known as carbon catabolite repression (CCR), which prioritizes some carbon sources over others when all are present in sufficient amounts. This optimizes growth by distributing metabolite fluxes, but can restrict yields in biotechnological applications. The molecular mechanisms and preferred substrates for CCR vary between bacterial groups. Escherichia coli prioritizes glucose whereas Pseudomonas sp. prefer certain organic acids or amino acids. A significant issue in understanding (and potentially bypassing) CCR is the lack of information about the signals that trigger this regulatory response. In E. coli, several key compounds act as flux sensors, governing the flow of metabolites through catabolic pathways and preventing imbalances. These flux sensors can also modulate the CCR response. It has been suggested that the order of substrate preference is determined by carbon uptake flux rather than substrate identity. For Pseudomonas, much less information is available, as the signals that induce CCR are poorly understood. This article briefly discusses the available evidence on the signals that trigger CCR and the questions that remain to be answered in Pseudomonas.

Development of a whole‐cell biosensor for ethylene oxide and ethylene

“…The control of the ethylene catabolic system resembles that of the butane oxidation system of T. butanivora (Dietrich et al., 2013 ), where the first metabolite (1‐butanol) is the inducer; we hypothesise that it is easier for bacteria to evolve sensors for functionalised molecules like alcohols and epoxides compared to the unreactive hydrocarbons that are the primary substrates of these pathways. A potential issue for our biosensor and similar whole‐cell biosensors is whether global regulatory systems such as catabolite repression (Moreno & Rojo, 2024 ) may impact their function. Although the ethylene regulatory genes have been removed from their normal host context, it is possible that common catabolite repression systems exist in both M.chubuense and M.smegmatis which might impact biosensor function, depending on the media used for experiments.…”

Inactivation of Pseudomonas putida KT2440 pyruvate dehydrogenase relieves catabolite repression and improves the usefulness of this strain for degrading aromatic compounds

“…In many bacterial genera, glucose is the preferred carbon source. Although glucose is not the most preferred carbon source for Pseudomonas , it is preferred to other ones, such as hydrocarbons (Görke & Stülke, 2008 ; Moreno & Rojo, 2024 ; Rojo, 2010 ).…”