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Production and characterization of a thermostable alcohol dehydrogenase that belongs to the aldo-keto reductase superfamily.

ABSTRACT: The gene encoding a novel alcohol dehydrogenase that belongs to the aldo-keto reductase superfamily has been identified in the hyperthermophilic archaeon Pyrococcus furiosus. The gene, referred to as adhD, was functionally expressed in Escherichia coli and subsequently purified to homogeneity. The enzyme has a monomeric conformation with a molecular mass of 32 kDa. The catalytic activity of the enzyme increases up to 100 degrees C, and a half-life value of 130 min at this temperature indicates its high thermostability. AdhD exhibits a broad substrate specificity with, in general, a preference for the reduction of ketones (pH optimum, 6.1) and the oxidation of secondary alcohols (pH optimum, 8.8). Maximal specific activities were detected with 2,3-butanediol (108.3 U/mg) and diacetyl-acetoin (22.5 U/mg) in the oxidative and reductive reactions, respectively. Gas chromatrography analysis indicated that AdhD produced mainly (S)-2-pentanol (enantiomeric excess, 89%) when 2-pentanone was used as substrate. The physiological role of AdhD is discussed.

SUBMITTER: Machielsen R

PROVIDER: S-EPMC1352300 | biostudies-literature | 2006 Jan

REPOSITORIES: biostudies-literature

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Production and characterization of a thermostable alcohol dehydrogenase that belongs to the aldo-keto reductase superfamily.

Machielsen Ronnie R Uria Agustinus R AR Kengen Servé W M SW van der Oost John J

Applied and environmental microbiology 20060101 1

The gene encoding a novel alcohol dehydrogenase that belongs to the aldo-keto reductase superfamily has been identified in the hyperthermophilic archaeon Pyrococcus furiosus. The gene, referred to as adhD, was functionally expressed in Escherichia coli and subsequently purified to homogeneity. The enzyme has a monomeric conformation with a molecular mass of 32 kDa. The catalytic activity of the enzyme increases up to 100 degrees C, and a half-life value of 130 min at this temperature indicates i ...[more]

PMID: 16391048

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Project description:Aldo-keto reductases (AKRs) are phase I metabolising enzymes that catalyse the reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H)-dependent reduction of carbonyl groups to yield primary and secondary alcohols on a wide range of substrates, including aliphatic and aromatic aldehydes and ketones, ketoprostaglandins, ketosteroids and xenobiotics. In so doing they functionalise the carbonyl group for conjugation (phase II enzyme reactions). Although functionally diverse, AKRs form a protein superfamily based on their high sequence identity and common protein fold, the (alpha/beta) 8 -barrel structure. Well over 150 AKR enzymes, from diverse organisms, have been annotated so far and given systematic names according to a nomenclature that is based on multiple protein sequence alignment and degree of identity. Annotation of non-vertebrate AKRs at the National Center for Biotechnology Information or Vertebrate Genome Annotation (vega) database does not often include the systematic nomenclature name, so the most comprehensive overview of all annotated AKRs is found on the AKR website (http://www.med.upenn.edu/akr/). This site also hosts links to more detailed and specialised information (eg on crystal structures, gene expression and single nucleotide polymorphisms [SNPs]). The protein-based AKR nomenclature allows unambiguous identification of a given enzyme but does not reflect the wealth of genomic and transcriptomic variation that exists in the various databases. In this context, identification of putative new AKRs and their distinction from pseudogenes are challenging. This review provides a short summary of the characteristic features of AKR biochemistry and structure that have been reviewed in great detail elsewhere, and focuses mainly on nomenclature and database entries of human AKRs that so far have not been subject to systematic annotation. Recent developments in the annotation of SNP and transcript variance in AKRs are also summarised.

Project description:The aldo-keto reductases metabolize a wide range of substrates and are potential drug targets. This protein superfamily includes aldose reductases, aldehyde reductases, hydroxysteroid dehydrogenases and dihydrodiol dehydrogenases. By combining multiple sequence alignments with known three-dimensional structures and the results of site-directed mutagenesis studies, we have developed a structure/function analysis of this superfamily. Our studies suggest that the (alpha/beta)8-barrel fold provides a common scaffold for an NAD(P)(H)-dependent catalytic activity, with substrate specificity determined by variation of loops on the C-terminal side of the barrel. All the aldo-keto reductases are dependent on nicotinamide cofactors for catalysis and retain a similar cofactor binding site, even among proteins with less than 30% amino acid sequence identity. Likewise, the aldo-keto reductase active site is highly conserved. However, our alignments indicate that variation ofa single residue in the active site may alter the reaction mechanism from carbonyl oxidoreduction to carbon-carbon double-bond reduction, as in the 3-oxo-5beta-steroid 4-dehydrogenases (Delta4-3-ketosteroid 5beta-reductases) of the superfamily. Comparison of the proposed substrate binding pocket suggests residues 54 and 118, near the active site, as possible discriminators between sugar and steroid substrates. In addition, sequence alignment and subsequent homology modelling of mouse liver 17beta-hydroxysteroid dehydrogenase and rat ovary 20alpha-hydroxysteroid dehydrogenase indicate that three loops on the C-terminal side of the barrel play potential roles in determining the positional and stereo-specificity of the hydroxysteroid dehydrogenases. Finally, we propose that the aldo-keto reductase superfamily may represent an example of divergent evolution from an ancestral multifunctional oxidoreductase and an example of convergent evolution to the same active-site constellation as the short-chain dehydrogenase/reductase superfamily.

Project description:Aldo-keto reductase (AKR) 1C15, a member of the AKR superfamily, was recently identified and cloned, and reported to alleviate oxidative stress in endothelial cells in rodent lungs. However, its expression and role in the brain and ischemic brain diseases have not been investigated. AKR1C15 expression was detected with real-time PCR. Mouse ischemic stroke and ischemic preconditioning (IPC) were established with middle cerebral artery occlusion (MCAO) for 1 h or 12 min, respectively. Recombinant AKR1C15 was administered intraperitoneally, and stroke outcome was evaluated with neurobehavioral tests and infarct volumes. Rat primary brain cell cultures were subjected to oxygen-glucose deprivation (OGD) to mimic ischemic injury. Cell survival or in vitro blood-brain barrier (BBB) permeability was measured, and nitric oxide (NO) release was detected. Immunostaining and Western blotting were used to evaluate oxidative-stress-related protein expression. AKR1C15 administration decreased the infarct volume and neurological deficits 2d post-stroke, and its early (1-h) administration after IPC abolished the protection of IPC against stroke. In rat primary brain cell cultures, AKR1C15 was most abundantly expressed in brain microvascular endothelial cells (BMVECs) and microglia. Its expression decreased upon OGD in most cell types except for BMVECs and microglia. In primary neuronal cultures, AKR1C15 treatment prevented OGD-induced cell death accompanied by decreased levels of 4-hydroxynonenal, 8-hydroxy-2'-deoxyguanosine, and heme oxygenase-1. In BMVEC cultures, AKR1C15 treatment protected against OGD-induced cell death and in vitro BBB leakage. In primary microglial cultures, AKR1C15 reduced the release of NO upon proinflammatory stimulation. Our results provide a characterization of the novel antioxidant AKR1C15 and demonstrate its protective role against ischemic injury, both in vivo and in vitro. AKR1C15 may be a promising agent for ischemic stroke treatment.

Dataset Information

Production and characterization of a thermostable alcohol dehydrogenase that belongs to the aldo-keto reductase superfamily.

Publications

Production and characterization of a thermostable alcohol dehydrogenase that belongs to the aldo-keto reductase superfamily.

Similar Datasets

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