Anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) via benzoyl-coenzyme A (CoA) and cyclohex-1-enecarboxyl-CoA in a denitrifying bacterium

J Bacteriol. 1992 Jun;174(11):3621-8. doi: 10.1128/jb.174.11.3621-3628.1992.


The enzymes catalyzing the initial reactions in the anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) were studied with a denitrifying Pseudomonas sp. anaerobically grown with 2-aminobenzoate and nitrate as the sole carbon and energy sources. Cells grown on 2-aminobenzoate are simultaneously adapted to growth with benzoate, whereas cells grown on benzoate degrade 2-aminobenzoate several times less efficiently than benzoate. Evidence for a new reductive pathway of aromatic metabolism and for four enzymes catalyzing the initial steps is presented. The organism contains 2-aminobenzoate-coenzyme A ligase (2-aminobenzoate-CoA ligase), which forms 2-aminobenzoyl-CoA. 2-Aminobenzoyl-CoA is then reductively deaminated to benzoyl-CoA by an oxygen-sensitive enzyme, 2-aminobenzoyl-CoA reductase (deaminating), which requires a low potential reductant [Ti(III)]. The specific activity is 15 nmol of 2-aminobenzoyl-CoA reduced min-1 mg-1 of protein at an optimal pH of 7. The two enzymes are induced by the substrate under anaerobic conditions only. Benzoyl-CoA is further converted in vitro by reduction with Ti(III) to six products; the same products are formed when benzoyl-CoA or 2-aminobenzoyl-CoA is incubated under reducing conditions. Two of them were identified preliminarily. One product is cyclohex-1-enecarboxyl-CoA, the other is trans-2-hydroxycyclohexane-carboxyl-CoA. The complex transformation of benzoyl-CoA is ascribed to at least two enzymes, benzoyl-CoA reductase (aromatic ring reducing) and cyclohex-1-enecarboxyl-CoA hydratase. The reduction of benzoyl-CoA to alicyclic compounds is catalyzed by extracts from cells grown anaerobically on either 2-aminobenzoate or benzoate at almost the same rate (10 to 15 nmol min-1 mg-1 of protein). In contrast, extracts from cells grown anaerobically on acetate or grown aerobically on benzoate or 2-aminobenzoate are inactive. This suggests a sequential induction of the enzymes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyl Coenzyme A / metabolism*
  • Adaptation, Biological
  • Anaerobiosis
  • Benzoates / metabolism
  • Benzoic Acid
  • Coenzyme A Ligases / metabolism*
  • Enzyme Induction
  • Enzymes / analysis
  • Nitrates / metabolism
  • Nitrites / metabolism
  • Oxidoreductases Acting on CH-NH Group Donors / metabolism
  • Pseudomonas / metabolism*
  • ortho-Aminobenzoates / metabolism*


  • Acyl Coenzyme A
  • Benzoates
  • Enzymes
  • Nitrates
  • Nitrites
  • cyclohex-1-enecarboxyl-coenzyme A
  • ortho-Aminobenzoates
  • anthranilic acid
  • benzoyl-coenzyme A
  • Benzoic Acid
  • 2-aminobenzoyl-CoA reductase (deaminating)
  • Oxidoreductases Acting on CH-NH Group Donors
  • 2-aminobenzoate coenzyme A ligase
  • Coenzyme A Ligases