Anaerobic metabolism of 3-hydroxybenzoate by the denitrifying bacterium Thauera aromatica

J Bacteriol. 2001 Feb;183(3):968-79. doi: 10.1128/JB.183.3.968-979.2001.


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 beta-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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyl Coenzyme A / metabolism
  • Anaerobiosis
  • Cloning, Molecular
  • Coenzyme A Ligases / isolation & purification*
  • Enzyme Induction
  • Genes, Bacterial
  • Hydroxybenzoates / metabolism*
  • Models, Genetic
  • Molecular Sequence Data
  • Nitrates / metabolism
  • Nitrites
  • Oxidation-Reduction
  • Oxidoreductases / isolation & purification
  • Oxidoreductases / metabolism
  • Oxidoreductases Acting on CH-CH Group Donors*
  • Sequence Analysis, DNA
  • Sequence Analysis, Protein
  • Substrate Specificity
  • Thauera / metabolism*


  • 3-hydroxybenzoyl-coenzyme A
  • Acyl Coenzyme A
  • Hydroxybenzoates
  • Nitrates
  • Nitrites
  • 3-hydroxybenzoic acid
  • Oxidoreductases
  • Oxidoreductases Acting on CH-CH Group Donors
  • benzoyl-coenzyme A reductase (dearomatizing)
  • 3-hydroxybenzoate coenzyme A ligase
  • Coenzyme A Ligases

Associated data

  • GENBANK/AJ278289