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.
Mikrobiologie, Institut Biologie II, Universität Freiburg, Freiburg, Germany.
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D
Laempe
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Jahn
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Fuchs
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