The Catabolic Network of Aromatoleum aromaticum EbN1T.
Microb Physiol
; 2023 Oct 10.
Article
in En
| MEDLINE
| ID: mdl-37816339
ABSTRACT
The denitrifying betaproteobacterium Aromatoleum aromaticum EbN1T is a facultative anaerobic degradation specialist and belongs to the environmental bacteria studied best on the proteogenomic level. This review summarizes the current state of knowledge about the anaerobic and aerobic degradation (to CO2) of 47 organic growth substrates (23 aromatic, 21 aliphatic, and 3 amino acids) as well as the modes of respiratory energy conservation (denitrification vs. O2-respiration). The constructed catabolic network is comprised of 256 genes, which occupy ~7.5% of the coding regions of the genome. In total 219 encoded proteins have been identified by differential proteomics, yielding a proteome coverage of ~74% of the network. Its degradation section is composed of 31 peripheral and 4 central pathways, with several peripheral modules (e.g., for 4-ethylphenol, 2-phenylethylamine, indoleacetate, and phenylpropanoids) discovered only after the complete genome [Rabus et al., Arch Microbiol 2005 Jan;183(1)27â36] and a first proteomic survey [Wöhlbrand et al., Proteomics 2007 Jun;7(13)2222â39] of A. aromaticum EbN1T were reported. The activation of recalcitrant aromatic compounds involves a suite of biochemically intriguing reactions ranging from CïH-bond activation (e.g., ethylbenzene dehydrogenase) via carboxylation (e.g., acetophenone carboxylase) to oxidative deamination (e.g., benzylamine), reductive dearomatization (benzoyl-CoA), and epoxide-forming oxygenases (e.g., phenylacetyl-CoA). The peripheral reaction sequences are substrate-specifically induced, mediated by specific transcriptional regulators with in vivo response thresholds in the nanomolar range. While lipophilic substrates (e.g., phenolics) enter the cells via passive diffusion, polar ones require active uptake that is driven by specific transporters. Next to the protein repertoire for canonical complexes IâIII, denitrification and O2-respiration (low and high affinity oxidases), the genome encodes an Ndh-II, a tetrathionate reductase, two ETFquinone oxidoreductases, and two Rnf-type complexes, broadening the electron transfer flexibility of the strain. Taken together, the detailed catabolic network presented here forms a solid basis for future systems biology level studies with A. aromaticum EbN1T.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Microb Physiol
Year:
2023
Document type:
Article
Publication country:
CH
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SUIZA
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SUÍÇA
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SWITZERLAND