Alcohol dehydrogenases in Acinetobacter sp. strain HO1-N: role in hexadecane and hexadecanol metabolism.
Multiple alcohol dehydrogenases (ADH) were demonstrated in Acinetobacter sp. strain HO1-N. ADH-A and ADH-B were distinguished on the basis of electrophoretic mobility, pyridine nucleotide cofactor requirement, and substrate specificity. ADH-A is a soluble, NAD-linked, inducible ethanol dehydrogenase (EDH) exhibiting an apparent Km for ethanol of 512 microM and a Vmax of 138 nmol/min. An ethanol-negative mutant (Eth1) was isolated which contained 6.5% of wild-type EDH activity and was deficient in ADH-A. Eth1 exhibited normal growth on hexadecane and hexadecanol. A second ethanol-negative mutant (Eth3) was acetaldehyde dehydrogenase (ALDH) deficient, having 12.5% of wild-type ALDH activity. Eth3 had threefold-higher EDH activity than the wild-type strain. ALDH is a soluble, NAD-linked, ethanol-inducible enzyme which exhibited an apparent Km for acetaldehyde of 50 microM and a Vmax of 183 nmol/min. Eth3 exhibited normal growth on hexadecane, hexadecanol, and fatty aldehyde. ADH-B is a soluble, constitutive, NADP-linked ADH which was active with medium-chain-length alcohols. Hexadecanol dehydrogenase (HDH), a soluble and membrane-bound, NAD-linked ADH, was induced 5- to 11-fold by growth on hexadecane or hexadecanol. HDH exhibited apparent Kms for hexadecanol of 1.6 and 2.8 microM in crude extracts derived from hexadecane- and hexadecanol-grown cells, respectively. HDH was distinct from ADH-A and ADH-B, since HDH and ADH-A were not coinduced; Eth1 had wild-type levels of HDH; and HDH requires NAD, while ADH-B requires NADP. NAD- and NADP-independent HDH activity was not detected in the soluble or membrane fraction of extracts derived from hexadecane- or hexadecanol-grown cells. NAD-linked HDH appears to possess a functional role in hexadecane and hexadecanol dissimilation.
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D000150:Acinetobacter / Q000201:enzymology*; D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000473:Alkanes / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism; D005233:Fatty Alcohols / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D013379:Substrate Specificity
D000473:Alkanes; D005233:Fatty Alcohols; D007527:Isoenzymes; D009243:NAD; D000431:Ethanol; D009249:NADP; C005031:cetyl alcohol; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; C007932:n-hexadecane