Aerobic benzoyl-coenzyme A (CoA) catabolic pathway in Azoarcus evansii: conversion of ring cleavage product by 3,4-dehydroadipyl-CoA semialdehyde dehydrogenase.
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.
Mikrobiologie, Institut für Biologie II, Universität Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany.
Johannes
J
Gescher
Wael
W
Ismail
Ellen
E
Olgeschläger
Wolfgang
W
Eisenreich
Jürgen
J
Wörth
Georg
G
Fuchs
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000272:Adipates / Q000378:metabolism; D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D020627:Azoarcus / Q000201:enzymology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001565:Benzoates / Q000378:metabolism; D003001:Cloning, Molecular; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D008970:Molecular Weight; D005810:Multigene Family; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D000214:Acyl Coenzyme A; D000272:Adipates; D001426:Bacterial Proteins; D001565:Benzoates; D011994:Recombinant Proteins; C027316:3-oxoadipic acid; C037817:benzoyl-coenzyme A; D000444:Aldehyde Dehydrogenase