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Metabolism of carveol and dihydrocarveol in Rhodococcus erythropolis DCL14

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Author: Werf, M.J. van der · Boot, A.M.
Type:article
Date:2000
Institution: Centraal Instituut voor Voedingsonderzoek TNO
Source:Microbiology, 5, 146, 1129-1141
Identifier: 41538
Keywords: Nutrition · Carveol · Carvone · Dihydrocarveol · Monoterpene metabolism · Rhodococcus erythropolis · Bacterial enzyme · Carveol · Carvone · Dihydrocarveol · Hexanoic acid derivative · Isomerase · Nicotinamide adenine dinucleotide · Oxepane derivative · Oxidoreductase · Oxygenase · Unclassified drug · Bacterial metabolism · Controlled study · Enzyme activity · Nonhuman · Priority journal · Rhodococcus · Stereoisomerism · 2,6-Dichloroindophenol · Alcohol Oxidoreductases · Anaerobiosis · Biodegradation, Environmental · Cyclohexenes · Hydrolases · Isomerases · Monoterpenes · Rhodococcus · Stereoisomerism · Terpenes · Actinobacteria (class) · Bacteria (microorganisms) · Erythropolis · Rhodococcus erythropolis · Uncultured actinomycete

Abstract

Rhodococcus euythropolis DCL14 assimilates all stereoisomers of carveol and dihydrocarveol as sole source of carbon and energy. Induction experiments with carveol- or dihydrocarveol-grown cells showed high oxygen consumption rates with these two compounds and with carvone and dihydrocarvone. (Dihydro)carveol-grown cells of R. erythropolis DCL14 contained the following enzymic activities involved in the carveol and dihydrocarveol degradation pathways of this micro-organism: (dihydro)carveol dehydrogenase (both NAD+- and dichlorophenolindophenol-dependent activities), an unknown cofactor-dependent carvone reductase, (iso-)dihydrocarvone isomerase activity, NADPH-dependent dihydrocarvone monooxygenase (Baeyer-Villiger monooxygenase), ε-lactone hydrolase and an NAD+-dependent 6-hydroxy-3-isopropenylheptanoate dehydrogenase. Product accumulation studies identified (4R)-carvone, (1R,4R)-dihydrocarvone, (4R,7R)-4-isopropenyl-7-methyl-2-oxo-oxepanone, (3R)-6-hydroxy-3-isopropenylheptanoate, (3R)-3-isopropenyl -6-oxoheptanoate, (3S,6R)-6-isopropenyl-3-methyl-2-oxo-oxepanone and (5R)-6-hydroxy-5-isopropenyl-2-methylhexanoate as intermediates in the (4R)carveol degradation pathway. The opposite stereoisomers of these compounds were identified in the (4S)-carveol degradation pathway. With dihydrocarveol, the same intermediates are involved except that carvone was absent. These results show that it. erythropolis DCL14 metabolizes all four diastereomers of carveol via oxidation to carvone, which is subsequently stereospecifically reduced to (1R)-(iso-) dihydrocarvone. At this point also dihydrocarveol enters the pathway, and this compound is directly oxidized to (iso-)dihydrocarvone. Cell extracts contained both (1R)-(iso-)dihydrocarvone 1,2-monooxygenase and (1S)-(iso)-dihydrocarvone 2,3-monooxygenase activity, resulting in a branch point of the degradation pathway; (1R)-(iso-)dihydrocarvone was converted to 4-isopropenyl-7-methyl-2-oxo-oxepanone, while (1S)-(iso)-dihydrocarvone, which in vivo is isomerized to (1R)-(iso-)dihydrocarvone, was converted to 6-isopropenyl-3-methyl-2-oxo-oxepanone. 4-Isopropenyl-7-methyl-2-oxo-oxepanone is hydrolysed to 6-hydroxy-3-isopropenylheptanoate. which is subsequently oxidized to 3-isopropenyl-6-oxoheptanoate, thereby linking the (dihydro)carveol degradation pathways to the limonene degradation pathway of this micro-organism. 6-Isopropenyl-3-methyl-2-oxo-oxepanone is, in vitro, hydrolysed to 6-hydroxy-5-isopropenyl-2-methylhexanoate, which is thought to be a dead-end metabolite. Chemicals/CAS: 2,6-Dichloroindophenol, 956-48-9; Alcohol Oxidoreductases, EC 1.1.-; carveol dehydrogenase, EC 1.1.1.243; carveol, 99-48-9; Cyclohexenes; Hydrolases, EC 3.-; Isomerases, EC 5.-; limonene, 138-86-3; Monoterpenes; Terpenes