Differential induction of enzymes involved in anaerobic metabolism of aromatic compounds in the denitrifying bacterium Thauera aromatica

1998 ◽  
Vol 170 (2) ◽  
pp. 120-131 ◽  
Author(s):  
J. Heider ◽  
Matthias Boll ◽  
Klaus Breese ◽  
Sabine Breinig ◽  
Christa Ebenau-Jehle ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Anaerobic Metabolism ◽  
Denitrifying Bacterium ◽  
Thauera Aromatica ◽  
Induction Of Enzymes ◽  
Differential Induction

scholarly journals Anaerobic Metabolism of 3-Hydroxybenzoate by the Denitrifying Bacterium Thauera aromatica

2001 ◽  
Vol 183 (3) ◽  
pp. 968-979 ◽  
Author(s):  
Diana Laempe ◽  
Martina Jahn ◽  
Klaus Breese ◽  
Hermann Schägger ◽  
Georg Fuchs
Keyword(s):  
Anaerobic Metabolism ◽  
Protein Pattern ◽  
Cell Extract ◽  
Amino Acid Sequences ◽  
Denitrifying Bacterium ◽  
Thauera Aromatica ◽  
Coa Ligase ◽  
Complete Protein ◽  
Coa Reductase ◽  
Induced Proteins

ABSTRACT The anaerobic metabolism of 3-hydroxybenzoate was studied in the denitrifying bacterium Thauera aromatica. Cells grown with this substrate were adapted to grow with benzoate but not with 4-hydroxybenzoate. Vice versa, 4-hydroxybenzoate-grown cells did not utilize 3-hydroxybenzoate. The first step in 3-hydroxybenzoate metabolism is a coenzyme A (CoA) thioester formation, which is catalyzed by an inducible 3-hydroxybenzoate–CoA ligase. The enzyme was purified and characterized. Further metabolism of 3-hydroxybenzoyl-CoA by cell extract required MgATP and was coupled to the oxidation of 2 mol of reduced viologen dyes per mol of substrate added. Purification of the 3-hydroxybenzoyl-CoA reducing enzyme revealed that this activity was due to benzoyl-CoA reductase, which reduced the 3-hydroxy analogue almost as efficiently as benzoyl-CoA. The further metabolism of the alicyclic dienoyl-CoA product containing the hydroxyl substitution obviously required additional specific enzymes. Comparison of the protein pattern of 3-hydroxybenzoate-grown cells with benzoate-grown cells revealed several 3-hydroxybenzoate-induced proteins; the N-terminal amino acid sequences of four induced proteins were determined and the corresponding genes were identified and sequenced. A cluster of six adjacent genes contained the genes for substrate-induced proteins 1 to 3; this cluster may not yet be complete. Protein 1 is a short-chain alcohol dehydrogenase. Protein 2 is a member of enoyl-CoA hydratase enzymes. Protein 3 was identified as 3-hydroxybenzoate–CoA ligase. Protein 4 is another member of the enoyl-CoA hydratases. In addition, three genes coding for enzymes of β-oxidation were present. The anaerobic 3-hydroxybenzoate metabolism here obviously combines an enzyme (benzoyl-CoA reductase) and electron carrier (ferredoxin) of the general benzoyl-CoA pathway with enzymes specific for the 3-hydroxybenzoate pathway. This raises some questions concerning the regulation of both pathways.

scholarly journals Anaerobic Metabolism of Catechol by the Denitrifying Bacterium Thauera aromatica—a Result of Promiscuous Enzymes and Regulators?

2007 ◽  
Vol 190 (5) ◽  
pp. 1620-1630 ◽  
Author(s):  
Bin Ding ◽  
Sirko Schmeling ◽  
Georg Fuchs
Keyword(s):  
Electron Acceptor ◽  
Anaerobic Metabolism ◽  
Regulatory Proteins ◽  
Hydroxyl Group ◽  
Denitrifying Bacterium ◽  
Aromatic Substrates ◽  
Thauera Aromatica ◽  
Coa Ligase ◽  
Coa Reductase ◽  
Lines Of Evidence

ABSTRACT The anaerobic metabolism of catechol (1,2-dihydroxybenzene) was studied in the betaproteobacterium Thauera aromatica that was grown with CO2 as a cosubstrate and nitrate as an electron acceptor. Based on different lines of evidence and on our knowledge of enzymes and genes involved in the anaerobic metabolism of other aromatic substrates, the following pathway is proposed. Catechol is converted to catechylphosphate by phenylphosphate synthase, which is followed by carboxylation by phenylphosphate carboxylase at the para position to the phosphorylated phenolic hydroxyl group. The product, protocatechuate (3,4-dihydroxybenzoate), is converted to its coenzyme A (CoA) thioester by 3-hydroxybenzoate-CoA ligase. Protocatechuyl-CoA is reductively dehydroxylated to 3-hydroxybenzoyl-CoA, possibly by 4-hydroxybenzoyl-CoA reductase. 3-Hydroxybenzoyl-CoA is further metabolized by reduction of the aromatic ring catalyzed by an ATP-driven benzoyl-CoA reductase. Hence, the promiscuity of several enzymes and regulatory proteins may be sufficient to create the catechol pathway that is made up of elements of phenol, 3-hydroxybenzoate, 4-hydroxybenzoate, and benzoate metabolism.

scholarly journals Solvent Stress Response of the Denitrifying Bacterium “Aromatoleum aromaticum” Strain EbN1

2008 ◽  
Vol 74 (8) ◽  
pp. 2267-2274 ◽  
Author(s):  
Kathleen Trautwein ◽  
Simon Kühner ◽  
Lars Wöhlbrand ◽  
Thomas Halder ◽  
Kenny Kuchta ◽  
...  
Keyword(s):  
Stress Responses ◽  
Aromatic Compounds ◽  
Gel Electrophoresis ◽  
Physiological Responses ◽  
Dry Weight ◽  
Anaerobic Growth ◽  
Solvent Concentration ◽  
Denitrifying Bacterium ◽  
Aromatic Substrates ◽  
Difference Gel Electrophoresis

ABSTRACT The denitrifying betaproteobacterium “Aromatoleum aromaticum” strain EbN1 degrades several aromatic compounds, including ethylbenzene, toluene, p-cresol, and phenol, under anoxic conditions. The hydrophobicity of these aromatic solvents determines their toxic properties. Here, we investigated the response of strain EbN1 to aromatic substrates at semi-inhibitory (about 50% growth inhibition) concentrations under two different conditions: first, during anaerobic growth with ethylbenzene (0.32 mM) or toluene (0.74 mM); and second, when anaerobic succinate-utilizing cultures were shocked with ethylbenzene (0.5 mM), toluene (1.2 mM), p-cresol (3.0 mM), and phenol (6.5 mM) as single stressors or as a mixture (total solvent concentration, 2.7 mM). Under all tested conditions impaired growth was paralleled by decelerated nitrate-nitrite consumption. Additionally, alkylbenzene-utilizing cultures accumulated poly(3-hydroxybutyrate) (PHB) up to 10% of the cell dry weight. These physiological responses were also reflected on the proteomic level (as determined by two-dimensional difference gel electrophoresis), e.g., up-regulation of PHB granule-associated phasins, cytochrome cd1 nitrite reductase of denitrification, and several proteins involved in oxidative (e.g., SodB) and general (e.g., ClpB) stress responses.

Sign in / Sign up

Export Citation Format

Share Document