Dataset Information

An aldo-keto reductase is responsible for Fusarium toxin-degrading activity in a soil Sphingomonas strain.

ABSTRACT: Degradation of toxins by microorganisms is a promising approach for detoxification of agricultural products. Here, a bacterial strain, Sphingomonas S3-4, that has the ability to degrade the mycotoxin deoxynivalenol (DON) was isolated from wheat fields. Incubation of Fusarium-infected wheat grains with S3-4 completely eliminated DON. In S3-4 DON is catabolized into compounds with no detectable phytotoxicity, 3-oxo-DON and 3-epi-DON, via two sequential reactions. Comparative analysis of genome sequences from two DON-degrading strains, S3-4 and Devosia D17, and one non-DON-degrading strain, Sphingobium S26, combined with functional screening of a S3-4 genomic BAC library led to the discovery that a novel aldo/keto reductase superfamily member, AKR18A1, is responsible for oxidation of DON into 3-oxo-DON. DON-degrading activity is completely abolished in a mutant S3-4 strain where the AKR18A1 gene is disrupted. Recombinant AKR18A1 protein expressed in Escherichia coli catalyzed the reversible oxidation/reduction of DON at a wide range of pH values (7.5 to 11) and temperatures (10 to 50?°C). The S3-4 strain and recombinant AKR18A1 also catabolized zearalenone and the aldehydes glyoxal and methyglyoxal. The S3-4 strain and the AKR18A1 gene are promising agents for the control of Fusarium pathogens and detoxification of mycotoxins in plants and in food/feed products.

SUBMITTER: He WJ

PROVIDER: S-EPMC5573404 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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An aldo-keto reductase is responsible for Fusarium toxin-degrading activity in a soil Sphingomonas strain.

He Wei-Jie WJ Zhang Limin L Yi Shu-Yuan SY Tang Xue-Ling XL Yuan Qing-Song QS Guo Mao-Wei MW Wu Ai-Bo AB Qu Bo B Li He-Ping HP Liao Yu-Cai YC

Scientific reports 20170825 1

Degradation of toxins by microorganisms is a promising approach for detoxification of agricultural products. Here, a bacterial strain, Sphingomonas S3-4, that has the ability to degrade the mycotoxin deoxynivalenol (DON) was isolated from wheat fields. Incubation of Fusarium-infected wheat grains with S3-4 completely eliminated DON. In S3-4 DON is catabolized into compounds with no detectable phytotoxicity, 3-oxo-DON and 3-epi-DON, via two sequential reactions. Comparative analysis of genome seq ...[more]

PMID: 28842569

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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.

Dataset Information

An aldo-keto reductase is responsible for Fusarium toxin-degrading activity in a soil Sphingomonas strain.

Publications

An aldo-keto reductase is responsible for Fusarium toxin-degrading activity in a soil Sphingomonas strain.

Similar Datasets

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