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Abraham N, Schroeter KL, Zhu Y, Chan J, Evans N, Kimber MS, Carere J, Zhou T, Seah SYK. Structure-function characterization of an aldo-keto reductase involved in detoxification of the mycotoxin, deoxynivalenol. Sci Rep 2022; 12:14737. [PMID: 36042239 PMCID: PMC9427786 DOI: 10.1038/s41598-022-19040-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 08/23/2022] [Indexed: 11/09/2022] Open
Abstract
Deoxynivalenol (DON) is a mycotoxin, produced by filamentous fungi such as Fusarium graminearum, that causes significant yield losses of cereal grain crops worldwide. One of the most promising methods to detoxify this mycotoxin involves its enzymatic epimerization to 3-epi-DON. DepB plays a critical role in this process by reducing 3-keto-DON, an intermediate in the epimerization process, to 3-epi-DON. DepBRleg from Rhizobium leguminosarum is a member of the new aldo-keto reductase family, AKR18, and it has the unusual ability to utilize both NADH and NADPH as coenzymes, albeit with a 40-fold higher catalytic efficiency with NADPH compared to NADH. Structural analysis of DepBRleg revealed the putative roles of Lys-217, Arg-290, and Gln-294 in NADPH specificity. Replacement of these residues by site-specific mutagenesis to negatively charged amino acids compromised NADPH binding with minimal effects on NADH binding. The substrate-binding site of DepBRleg is larger than its closest structural homolog, AKR6A2, likely contributing to its ability to utilize a wide range of aldehydes and ketones, including the mycotoxin, patulin, as substrates. The structure of DepBRleg also suggests that 3-keto-DON can adopt two binding modes to facilitate 4-pro-R hydride transfer to either the re- or si-face of the C3 ketone providing a possible explanation for the enzyme's ability to convert 3-keto-DON to 3-epi-DON and DON in diastereomeric ratios of 67.2% and 32.8% respectively.
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Affiliation(s)
- Nadine Abraham
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada.,Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Kurt L Schroeter
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
| | - Yan Zhu
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Jonathan Chan
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada.,Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Natasha Evans
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada.,Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Matthew S Kimber
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
| | - Jason Carere
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Ting Zhou
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Stephen Y K Seah
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada.
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Vargas JA, Leonardo DA, D’Muniz Pereira H, Lopes AR, Rodriguez HN, Cobos M, Marapara JL, Castro JC, Garratt RC. Structural Characterization of L-Galactose Dehydrogenase: An Essential Enzyme for Vitamin C Biosynthesis. PLANT & CELL PHYSIOLOGY 2022; 63:1140-1155. [PMID: 35765894 PMCID: PMC9381564 DOI: 10.1093/pcp/pcac090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/20/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
In plants, it is well-known that ascorbic acid (vitamin C) can be synthesized via multiple metabolic pathways but there is still much to be learned concerning their integration and control mechanisms. Furthermore, the structural biology of the component enzymes has been poorly exploited. Here we describe the first crystal structure for an L-galactose dehydrogenase [Spinacia oleracea GDH (SoGDH) from spinach], from the D-mannose/L-galactose (Smirnoff-Wheeler) pathway which converts L-galactose into L-galactono-1,4-lactone. The kinetic parameters for the enzyme are similar to those from its homolog from camu camu, a super-accumulator of vitamin C found in the Peruvian Amazon. Both enzymes are monomers in solution and have a pH optimum of 7, and their activity is largely unaffected by high concentrations of ascorbic acid, suggesting the absence of a feedback mechanism acting via GDH. Previous reports may have been influenced by changes of the pH of the reaction medium as a function of ascorbic acid concentration. The structure of SoGDH is dominated by a (β/α)8 barrel closely related to aldehyde-keto reductases (AKRs). The structure bound to NAD+ shows that the lack of Arg279 justifies its preference for NAD+ over NADP+, as employed by many AKRs. This favors the oxidation reaction that ultimately leads to ascorbic acid accumulation. When compared with other AKRs, residue substitutions at the C-terminal end of the barrel (Tyr185, Tyr61, Ser59 and Asp128) can be identified to be likely determinants of substrate specificity. The present work contributes toward a more comprehensive understanding of structure-function relationships in the enzymes involved in vitamin C synthesis.
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Affiliation(s)
| | | | - Humberto D’Muniz Pereira
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Adriana R Lopes
- Laboratory of Biochemistry, Instituto Butantan, Av. Vital Brasil, São Paulo 1500, Brazil
| | - Hicler N Rodriguez
- Unidad Especializada del Laboratorio de Investigación en Biotecnología (UELIB), Centro de Investigaciones de Recursos Naturales de la UNAP (CIRNA), Universidad Nacional de la Amazonia Peruana (UNAP), Psje. Los Paujiles S/N, Iquitos 1600, Peru
| | - Marianela Cobos
- Unidad Especializada del Laboratorio de Investigación en Biotecnología (UELIB), Centro de Investigaciones de Recursos Naturales de la UNAP (CIRNA), Universidad Nacional de la Amazonia Peruana (UNAP), Psje. Los Paujiles S/N, Iquitos 1600, Peru
- Laboratorio de Biotecnología y Bioenergética, Universidad Científica del Perú, Av. Abelardo Quiñones km 2.5, Iquitos 16006, Peru
- Departamento Académico de Ciencias Biomédicas y Biotecnología (DACBB), Facultad de Ciencias Biológicas (FCB), Universidad Nacional de la Amazonia Peruana (UNAP), Ciudad Universitaria - Zungarococha, San Juan Bautista 16000, Peru
| | - Jorge L Marapara
- Unidad Especializada del Laboratorio de Investigación en Biotecnología (UELIB), Centro de Investigaciones de Recursos Naturales de la UNAP (CIRNA), Universidad Nacional de la Amazonia Peruana (UNAP), Psje. Los Paujiles S/N, Iquitos 1600, Peru
- Departamento Académico de Ciencias Biomédicas y Biotecnología (DACBB), Facultad de Ciencias Biológicas (FCB), Universidad Nacional de la Amazonia Peruana (UNAP), Ciudad Universitaria - Zungarococha, San Juan Bautista 16000, Peru
| | - Juan C Castro
- Unidad Especializada del Laboratorio de Investigación en Biotecnología (UELIB), Centro de Investigaciones de Recursos Naturales de la UNAP (CIRNA), Universidad Nacional de la Amazonia Peruana (UNAP), Psje. Los Paujiles S/N, Iquitos 1600, Peru
- Departamento Académico de Ciencias Biomédicas y Biotecnología (DACBB), Facultad de Ciencias Biológicas (FCB), Universidad Nacional de la Amazonia Peruana (UNAP), Ciudad Universitaria - Zungarococha, San Juan Bautista 16000, Peru
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Lapthorn AJ, Zhu X, Ellis EM. The diversity of microbial aldo/keto reductases from Escherichia coli K12. Chem Biol Interact 2012; 202:168-77. [PMID: 23103600 DOI: 10.1016/j.cbi.2012.10.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 10/11/2012] [Accepted: 10/15/2012] [Indexed: 12/20/2022]
Abstract
The genome of Escherichia coli K12 contains 9 open reading frames encoding aldo/keto reductases (AKRs) that are differentially regulated and sequence diverse. A significant amount of data is available for the E. coli AKRs through the availability of gene knockouts and gene expression studies, which adds to the biochemical and kinetic data. This together with the availability of crystal structures for nearly half of the E. coli AKRs and homologues of several others provides an opportunity to look at the diversity of these representative bacterial AKRs. Based around the common AKR fold of (β/α)8 barrel with two additional α-helices, the E. coli AKRs have a loop structure that is more diverse than their mammalian counterparts, creating a variety of active site architectures. Nearly half of the AKRs are expected to be monomeric, but there are examples of dimeric, trimeric and octameric enzymes, as well as diversity in specificity for NAD as well as NADP as a cofactor. However in functional assignments and characterisation of enzyme activities there is a paucity of data when compared to the mammalian AKR enzymes.
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Affiliation(s)
- Adrian J Lapthorn
- School of Chemistry, University of Glasgow, Glasgow, United Kingdom.
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Maugé C, Granier T, d'Estaintot BL, Gargouri M, Manigand C, Schmitter JM, Chaudière J, Gallois B. Crystal structure and catalytic mechanism of leucoanthocyanidin reductase from Vitis vinifera. J Mol Biol 2010; 397:1079-91. [PMID: 20138891 DOI: 10.1016/j.jmb.2010.02.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Revised: 01/29/2010] [Accepted: 02/01/2010] [Indexed: 01/15/2023]
Abstract
Leucoanthocyanidin reductase (LAR) catalyzes the NADPH-dependent reduction of 2R,3S,4S-flavan-3,4-diols into 2R,3S-flavan-3-ols, a subfamily of flavonoids that is important for plant survival and for human nutrition. LAR1 from Vitis vinifera has been co-crystallized with or without NADPH and one of its natural products, (+)-catechin. Crystals diffract to a resolution between 1.75 and 2.72 A. The coenzyme and substrate binding pocket is preformed in the apoprotein and not markedly altered upon NADPH binding. The structure of the abortive ternary complex, determined at a resolution of 2.28 A, indicates the ordering of a short 3(10) helix associated with substrate binding and suggests that His122 and Lys140 act as acid-base catalysts. Based on our 3D structures, a two-step catalytic mechanism is proposed, in which a concerted dehydration precedes an NADPH-mediated hydride transfer at C4. The dehydration step involves a Lys-catalyzed deprotonation of the phenolic OH7 through a bridging water molecule and a His-catalyzed protonation of the benzylic hydroxyl at C4. The resulting quinone methide serves as an electrophilic target for hydride transfer at C4. LAR belongs to the short-chain dehydrogenase/reductase superfamily and to the PIP (pinoresinol-lariciresinol reductase, isoflavone reductase, and phenylcoumaran benzylic ether reductase) family. Our data support the concept that all PIP enzymes reduce a quinone methide intermediate and that the major role of the only residue that has been conserved from the short-chain dehydrogenase/reductase catalytic triad (Ser...TyrXXXLys), that is, lysine, is to promote the formation of this intermediate by catalyzing the deprotonation of a phenolic hydroxyl. For some PIP enzymes, this lysine-catalyzed proton abstraction may be sufficient to trigger the extrusion of the leaving group, whereas in LAR, the extrusion of a hydroxide group requires a more sophisticated mechanism of concerted acid-base catalysis that involves histidine and takes advantage of the OH4, OH5, and OH7 substituents of leucoanthocyanidins.
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Affiliation(s)
- Chloé Maugé
- Chimie et Biologie des Membranes et des Nanoobjets, UMR CNRS 5248, Bât. B8, Avenue des Facultés, Université Bordeaux 1, 33405 Talence Cedex, France
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Simpson PJ, Tantitadapitak C, Reed AM, Mather OC, Bunce CM, White SA, Ride JP. Characterization of two novel aldo-keto reductases from Arabidopsis: expression patterns, broad substrate specificity, and an open active-site structure suggest a role in toxicant metabolism following stress. J Mol Biol 2009; 392:465-80. [PMID: 19616008 DOI: 10.1016/j.jmb.2009.07.023] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 06/26/2009] [Accepted: 07/09/2009] [Indexed: 11/17/2022]
Abstract
Aldo-keto reductases (AKRs) are widely distributed in nature and play numerous roles in the metabolism of steroids, sugars, and other carbonyls. They have also frequently been implicated in the metabolism of exogenous and endogenous toxicants, including those stimulated by stress. Although the Arabidopsis genome includes at least 21 genes with the AKR signature, very little is known of their functions. In this study, we have screened the Arabidopsis thaliana genomic sequence for genes with significant homology to members of the mammalian AKR1 family and identified four homologues for further study. Following alignment of the predicted protein sequences with representatives from the AKR superfamily, the proteins were ascribed not to the AKR1 family but to the AKR4C subfamily, with the individual designations of AKR4C8, AKR4C9, AKR4C10, and AKR4C11. Expression of two of the genes, AKR4C8 and AKR4C9, has been shown to be coordinately regulated and markedly induced by various forms of stress. The genes have been overexpressed in bacteria, and recombinant proteins have been purified and crystallized. Both enzymes display NADPH-dependent reduction of carbonyl compounds, typical of the superfamily, but will accept a very wide range of substrates, reducing a range of steroids, sugars, and aliphatic and aromatic aldehydes/ketones, although there are distinct differences between the two enzymes. We have obtained high-resolution crystal structures of AKR4C8 (1.4 A) and AKR4C9 (1.25 A) in ternary complexes with NADP(+) and acetate. Three extended loops, present in all AKRs and responsible for defining the cofactor- and substrate-binding sites, are shorter in the 4C subfamily compared to other AKRs. Consequently, the crystal structures reveal open and accommodative substrate-binding sites, which correlates with their broad substrate specificity. It is suggested that the primary role of these enzymes may be to detoxify a range of toxic aldehydes and ketones produced during stress, although the precise nature of the principal natural substrates remains to be determined.
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Affiliation(s)
- Paul J Simpson
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK
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Marquardt T, Kostrewa D, Balakrishnan R, Gasperina A, Kambach C, Podjarny A, Winkler FK, Balendiran GK, Li XD. High-resolution crystal structure of AKR11C1 from Bacillus halodurans: an NADPH-dependent 4-hydroxy-2,3-trans-nonenal reductase. J Mol Biol 2005; 354:304-16. [PMID: 16242712 DOI: 10.1016/j.jmb.2005.09.067] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 09/20/2005] [Accepted: 09/21/2005] [Indexed: 11/20/2022]
Abstract
Aldo-keto reductase AKR11C1 from Bacillus halodurans, a new member of aldo-keto reductase (AKR) family 11, has been characterized structurally and biochemically. The structures of the apo and NADPH bound form of AKR11C1 have been solved to 1.25 A and 1.3 A resolution, respectively. AKR11C1 possesses a novel non-aromatic stacking interaction of an arginine residue with the cofactor, which may favor release of the oxidized cofactor. Our biochemical studies have revealed an NADPH-dependent activity of AKR11C1 with 4-hydroxy-2,3-trans-nonenal (HNE). HNE is a cytotoxic lipid peroxidation product, and detoxification in alkaliphilic bacteria, such as B.halodurans, plays a crucial role in survival. AKR11C1 could thus be part of the detoxification system, which ensures the well being of the microorganism. The very poor activity of AKR11C1 on standard, small substrates such as benzaldehyde or DL-glyeraldehyde is consistent with the observed, very open active site lacking a binding pocket for these substrates. In contrast, modeling of HNE with its aldehyde function suitably positioned in the active site suggests that its elongated hydrophobic tail occupies a groove defined by hydrophobic side-chains. Multiple sequence alignment of AKR11C1 with the highly homologous iolS and YqkF proteins shows a high level of conservation in this putative substrate-binding site. We suggest that AKR11C1 is the first structurally characterized member of a new class of AKRs with specificity for substrates with long aliphatic tails.
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Affiliation(s)
- Tobias Marquardt
- Biomolecular Research, Paul Scherrer Institut, 5232 Villigen, Switzerland
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