Aromatic degradative pathways in Acinetobacter baylyi underlie carbon catabolite repression

Abstract

Carbon catabolite repression is an important mechanism allowing efficient carbon source utilization. In the soil bacterium Acinetobacter baylyi, this mechanism has been shown to apply to the aromatic degradative pathways for the substrates protocatechuate, p-hydroxybenzoate and vanillate. In this investigation, transcriptional fusions with the gene for luciferase in the gene clusters for the degradation of benzyl esters, anthranilate, benzoate, hydroxycinnamates and dicarboxylates (are, ant, ben, hca and dca genes) were constructed and established in the chromosome of A. baylyi. The respective strains revealed the presence of strong carbon catabolite repression at the transcriptional level. In all cases, succinate and acetate in combination had the strongest repressing effect, and pyruvate (or lactate in case of the ben and hca genes) allowed the highest expression when these carbon sources were supplied together with the respective inducer. The pattern of repression for the different cosubstrates was similar for all operons investigated and was also observed in the absence of the respective inducing compounds, indicating a mechanism that is independent of the respective specific regulators. Repression by acetate and succinate varied between 88 % for the hca genes and 99 % for the pca genes.

Patterns of Endemism and Habitat Selection in Coalbed Microbial Communities

“…variable genomic regions may also reflect adaptive metabolic strategies. The ability to rapidly assimilate and degrade carbohydrates or organic acids that periodically become available in the coalbed environment may be preferentially used by Celeribacter sp., as has been shown for other Proteobacteria (79)(80)(81). While such compounds are not expected to be abundant in deep coalbeds, they may become available via biomass decay (82).…”

Benzoate Mediates Repression of C 4 -Dicarboxylate Utilization in “Aromatoleum aromaticum” EbN1

“…Utilization of succinate is often preferred over that of aromatic compounds (e.g., benzoate), as observed in aerobic degraders like P. putida (33) and A. baylyi (17) or in the anaerobic degrader Azoarcus sp. strain CIB (30 (Table 1).…”

Purification and Characterization of an NAD + -Dependent XylB-Like Aryl Alcohol Dehydrogenase Identified in Acinetobacter baylyi ADP1

“…In a last step, aromatic compounds are degraded via the ␤-ketoadipate pathway, in which the aromatic rings of the formed catechol or protocatechuate, which result from the degradation of hydroxycinnamyl alcohols, are cleaved by enzymes encoded by catA or pcaGH, respectively, with the formation of an intradiol being the most important step. The degradation products are finally channeled into the tricarboxylic acid cycle as succinyl coenzyme A (succinyl-CoA) and acetyl-CoA (5).…”

“…strain ADP1, which is an unencapsulated mutant of strain BD4 (11), became the focus of research due to its high natural competence (12). Detailed studies have been done on the molecular organization and evolution of genes involved in aromatic compound degradation (5,9,19), on the metabolism of storage lipids (14,24), and on the genome sequence of this interesting strain (1).…”