Aerobic benzoyl-coenzyme A (CoA) catabolic pathway in Azoarcus evansii: conversion of ring cleavage product by 3,4-dehydroadipyl-CoA semialdehyde dehydrogenase

J Bacteriol. 2006 Apr;188(8):2919-27. doi: 10.1128/JB.188.8.2919-2927.2006.


Benzoate, a strategic intermediate in aerobic aromatic metabolism, is metabolized in various bacteria via an unorthodox pathway. The intermediates of this pathway are coenzyme A (CoA) thioesters throughout, and ring cleavage is nonoxygenolytic. The fate of the ring cleavage product 3,4-dehydroadipyl-CoA semialdehyde was studied in the beta-proteobacterium Azoarcus evansii. Cell extracts contained a benzoate-induced, NADP(+)-specific aldehyde dehydrogenase, which oxidized this intermediate. A postulated putative long-chain aldehyde dehydrogenase gene, which might encode this new enzyme, is located on a cluster of genes encoding enzymes and a transport system required for aerobic benzoate oxidation. The gene was expressed in Escherichia coli, and the maltose-binding protein-tagged enzyme was purified and studied. It is a homodimer composed of 54 kDa (without tag) subunits and was confirmed to be the desired 3,4-dehydroadipyl-CoA semialdehyde dehydrogenase. The reaction product was identified by nuclear magnetic resonance spectroscopy as the corresponding acid 3,4-dehydroadipyl-CoA. Hence, the intermediates of aerobic benzoyl-CoA catabolic pathway recognized so far are benzoyl-CoA; 2,3-dihydro-2,3-dihydroxybenzoyl-CoA; 3,4-dehydroadipyl-CoA semialdehyde plus formate; and 3,4-dehydroadipyl-CoA. The further metabolism is thought to lead to 3-oxoadipyl-CoA, the intermediate at which the conventional and the unorthodox pathways merge.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyl Coenzyme A / metabolism*
  • Adipates / metabolism
  • Aldehyde Dehydrogenase / genetics
  • Aldehyde Dehydrogenase / isolation & purification
  • Aldehyde Dehydrogenase / metabolism*
  • Amino Acid Sequence
  • Azoarcus / enzymology
  • Azoarcus / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / isolation & purification
  • Bacterial Proteins / metabolism
  • Benzoates / metabolism
  • Cloning, Molecular
  • Dimerization
  • Escherichia coli / genetics
  • Genes, Bacterial
  • Magnetic Resonance Spectroscopy
  • Molecular Sequence Data
  • Molecular Weight
  • Multigene Family
  • Oxidation-Reduction
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid


  • Acyl Coenzyme A
  • Adipates
  • Bacterial Proteins
  • Benzoates
  • Recombinant Proteins
  • 3-oxoadipic acid
  • benzoyl-coenzyme A
  • Aldehyde Dehydrogenase