Nanomolar Responsiveness of an Anaerobic Degradation Specialist to Alkylphenol Pollutants
| Autor: | Lars Wöhlbrand, John Neidhardt, Ralf Rabus, Arne Weiten, Kristin Kalvelage, Michael Winklhofer, Jannes Vagts, Sabine Scheve, Sebastian Swirski |
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| Rok vydání: | 2020 |
| Předmět: |
Proteome
Alkylphenol Mutant Rhodocyclaceae Bacterial growth Biology Microbiology 03 medical and health sciences Phenols Extracellular Anaerobiosis Molecular Biology 030304 developmental biology 0303 health sciences 030306 microbiology Wild type Gene Expression Regulation Bacterial Models Theoretical Biodegradation Complementation Biodegradation Environmental Biochemistry Mutation Environmental Pollutants Transcriptome Anaerobic exercise Algorithms Research Article |
| Zdroj: | J Bacteriol |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.00595-19 |
| Popis: | Anaerobic degradation of p-cresol (4-methylphenol) by the denitrifying betaproteobacterium Aromatoleum aromaticum EbN1 is regulated with high substrate specificity, presumed to be mediated by the predicted σ(54)-dependent two-component system PcrSR. An unmarked, in-frame ΔpcrSR deletion mutant showed reduced expression of the genes cmh (21-fold) and hbd (8-fold) that encode the two enzymes for initial oxidation of p-cresol to p-hydroxybenzoate compared to their expression in the wild type. The expression of cmh and hbd was restored by in trans complementation with pcrSR in the ΔpcrSR background to even higher levels than in the wild type. This is likely due to ∼200-/∼30-fold more transcripts of pcrSR in the complemented mutant. The in vivo responsiveness of A. aromaticum EbN1 to p-cresol was studied in benzoate-limited anaerobic cultures by the addition of p-cresol at various concentrations (from 100 μM down to 0.1 nM). Time-resolved transcript profiling by quantitative reverse transcription-PCR (qRT-PCR) revealed that the lowest p-cresol concentrations just affording cmh and hbd expression (response threshold) ranged between 1 and 10 nM, which is even more sensitive than the respective odor receptors of insects. A similar response threshold was determined for another alkylphenol, p-ethylphenol, which strain EbN1 anaerobically degrades via a different route and senses by the σ(54)-dependent one-component system EtpR. Based on these data and theoretical considerations, p-cresol or p-ethylphenol added as a single pulse (10 nM) requires less than a fraction of a second to reach equilibrium between intra- and extracellular space (∼20 molecules per cell), with an estimated K(d) (dissociation constant) of |
| Databáze: | OpenAIRE |
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