6-Hydroxycyclohex-1-ene-1-carbonyl-CoA dehydrogenase and 6-oxocyclohex-1-ene-1-carbonyl-CoA hydrolase, enzymes of the benzoyl-CoA pathway of anaerobic aromatic metabolism in the denitrifying bacterium Thauera aromatica.
Benzoyl-CoA is a common intermediate in the anaerobic bacterial metabolism of many aromatic substrates. Two enzymes and ferredoxin of the central benzoyl-CoA pathway in Thauera aromatica have been purified so far. Benzoyl-CoA reductase reduces the aromatic ring with reduced ferredoxin yielding cyclohexa-1,5-diene-1-carbonyl-CoA [Boll, M. & Fuchs, G. (1995) Eur. J. Biochem. 234, 921-933]. Dienoyl-CoA hydratase subsequently adds one molecule of water and thereby produces 6-hydroxycyclohex-1-ene-1-carbonyl-CoA [Laempe, D., Eisenreich, W., Bacher, A., & Fuchs, G. (1998) Eur. J. Biochem. 255, 618-627]. Here two new enzymes, which convert this intermediate to the noncyclic product 3-hydroxypimelyl-CoA, were purified from T. aromatica and studied. 6-Hydroxycyclohex-1-ene-1-carbonyl-CoA dehydrogenase is an NAD(+)-specific beta-hydroxyacyl-CoA dehydrogenase that catalyzes 6-hydroxycyclohex-1-ene-1-carbonyl-CoA + NAD(+) --> 6-oxocyclohex-1-ene-1-carbonyl-CoA + NADH + H(+). 6-Oxocyclohex-1-ene-1-carbonyl-CoA hydrolase acts on the beta-oxoacyl-CoA compound and catalyzes the addition of one molecule of water to the double bound and the hydrolytic C-C cleavage of the alicyclic ring, 6-oxocyclohex-1-ene-1-carbonyl-CoA + 2 H(2)O --> 3-hydroxypimelyl-CoA. The genes for both enzymes, had and oah, were cloned, had was overexpressed in Escherichia coli and the recombinant protein was purified. Hence, presumably all enzymes of the central benzoyl-CoA pathway of anaerobic aromatic metabolism from this organism have now been purified and studied and the corresponding genes have been cloned and sequenced.
Laempe
D
D
Mikrobiologie, Institut Biologie II, Universität Freiburg, Freiburg, Germany.
Jahn
M
M
Fuchs
G
G
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000302:isolation & purification*; D001421:Bacteria, Anaerobic / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000201:enzymology; D006867:Hydrolases / Q000737:chemistry* / Q000302:isolation & purification*; D013058:Mass Spectrometry; D008956:Models, Chemical; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases
D000214:Acyl Coenzyme A; C037817:benzoyl-coenzyme A; D000429:Alcohol Oxidoreductases; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; C114725:6-hydroxycyclohex-1-ene-1-carbonyl-CoA dehydrogenase; D006867:Hydrolases; C120741:6-oxocyclohex-1-ene-1-carbonyl-CoA hydrolase