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Heath RS, Sangster JJ, Turner NJ. An Engineered Cholesterol Oxidase Catalyses Enantioselective Oxidation of Non-steroidal Secondary Alcohols. Chembiochem 2022; 23:e202200075. [PMID: 35143703 PMCID: PMC9303356 DOI: 10.1002/cbic.202200075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/09/2022] [Indexed: 11/23/2022]
Abstract
The enantioselective oxidation of 2° alcohols to ketones is an important reaction in synthetic chemistry, especially if it can be achieved using O2 -driven alcohol oxidases under mild reaction conditions. However to date, oxidation of secondary alcohols using alcohol oxidases has focused on activated benzylic or allylic substrates, with unactivated secondary alcohols showing poor activity. Here we show that cholesterol oxidase (EC 1.1.3.6) could be engineered for activity towards a range of aliphatic, cyclic, acyclic, allylic and benzylic secondary alcohols. Additionally, since the variants demonstrated high (S)-selectivity, deracemisation reactions were performed in the presence of ammonia borane to obtain enantiopure (R)-alcohols.
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Affiliation(s)
- Rachel S. Heath
- Department of ChemistryUniversity of ManchesterManchester Institute of Biotechnology131 Princess StreetM1 7DNManchesterUK
| | - Jack J. Sangster
- Department of ChemistryUniversity of ManchesterManchester Institute of Biotechnology131 Princess StreetM1 7DNManchesterUK
| | - Nicholas J. Turner
- Department of ChemistryUniversity of ManchesterManchester Institute of Biotechnology131 Princess StreetM1 7DNManchesterUK
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2
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Tjallinks G, Martin C, Fraaije MW. Enantioselective oxidation of secondary alcohols by the flavoprotein alcohol oxidase from Phanerochaete chrysosporium. Arch Biochem Biophys 2021; 704:108888. [PMID: 33910055 DOI: 10.1016/j.abb.2021.108888] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 11/19/2022]
Abstract
The enantioselective oxidation of secondary alcohols represents a valuable approach for the synthesis of optically pure compounds. Flavoprotein oxidases can catalyse such selective transformations by merely using oxygen as electron acceptor. While many flavoprotein oxidases preferably act on primary alcohols, the FAD-containing alcohol oxidase from Phanerochaete chrysosporium was found to be able to perform kinetic resolutions of several secondary alcohols. By selective oxidation of the (S)-alcohols, the (R)-alcohols were obtained in high enantiopurity. In silico docking studies were carried out in order to substantiate the observed (S)-selectivity. Several hydrophobic and aromatic residues in the substrate binding site create a cavity in which the substrates can comfortably undergo van der Waals and pi-stacking interactions. Consequently, oxidation of the secondary alcohols is restricted to one of the two enantiomers. This study has uncovered the ability of an FAD-containing alcohol oxidase, that is known for oxidizing small primary alcohols, to perform enantioselective oxidations of various secondary alcohols.
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Affiliation(s)
- Gwen Tjallinks
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, Groningen, the Netherlands
| | - Caterina Martin
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, Groningen, the Netherlands
| | - Marco W Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, Groningen, the Netherlands.
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3
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Messenlehner J, Hetman M, Tripp A, Wallner S, Macheroux P, Gruber K, Daniel B. The catalytic machinery of the FAD-dependent AtBBE-like protein 15 for alcohol oxidation: Y193 and Y479 form a catalytic base, Q438 and R292 an alkoxide binding site. Arch Biochem Biophys 2021; 700:108766. [PMID: 33485849 DOI: 10.1016/j.abb.2021.108766] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Abstract
Monolignol oxidoreductases are members of the berberine bridge enzyme-like (BBE-like) protein family (pfam 08031) that oxidize monolignols to the corresponding aldehydes. They are FAD-dependent enzymes that exhibit the para-cresolmethylhydroxylase-topology, also known as vanillyl oxidase-topology. Recently, we have reported the structural and biochemical characterization of two monolignol oxidoreductases from Arabidopsis thaliana, AtBBE13 and AtBBE15. Now, we have conducted a comprehensive site directed mutagenesis study for AtBBE15, to expand our understanding of the catalytic mechanism of this enzyme class. Based on the kinetic properties of active site variants and molecular dynamics simulations, we propose a refined, structure-guided reaction mechanism for the family of monolignol oxidoreductases. Here, we propose that this reaction is facilitated stepwise by the deprotonation of the allylic alcohol and a subsequent hydride transfer from the Cα-atom of the alkoxide to the flavin. We describe an excessive hydrogen bond network that enables the catalytic mechanism of the enzyme. Within this network Tyr479 and Tyr193 act concertedly as active catalytic bases to facilitate the proton abstraction. Lys436 is indirectly involved in the deprotonation as this residue determines the position of Tyr193 via a cation-π interaction. The enzyme forms a hydrophilic cavity to accommodate the alkoxide intermediate and to stabilize the transition state from the alkoxide to the aldehyde. By means of molecular dynamics simulations, we have identified two different and distinct binding modes for the substrate in the alcohol and alkoxide state. The alcohol interacts with Tyr193 and Tyr479 while Arg292, Gln438 and Tyr193 form an alkoxide binding site to accommodate this intermediate. The pH-dependency of the activity of the active site variants revealed that the integrity of the alkoxide binding site is also crucial for the fine tuning of the pKa of Tyr193 and Tyr479. Sequence alignments showed that key residues for the mechanism are highly conserved, indicating that our proposed mechanism is not only relevant for AtBBE15 but for the majority of BBE-like proteins.
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Affiliation(s)
- Julia Messenlehner
- Graz University of Technology, NAWI Graz, Institute of Biochemistry, Graz, Austria
| | - Michael Hetman
- University of Graz, NAWI Graz, Institute of Molecular Biosciences, Graz, Austria; Acib-Austrian Centre of Industrial Biotechnology, Krenngasse 37, Graz, Austria
| | - Adrian Tripp
- Graz University of Technology, NAWI Graz, Institute of Biochemistry, Graz, Austria
| | - Silvia Wallner
- Graz University of Technology, NAWI Graz, Institute of Biochemistry, Graz, Austria
| | - Peter Macheroux
- Graz University of Technology, NAWI Graz, Institute of Biochemistry, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Karl Gruber
- University of Graz, NAWI Graz, Institute of Molecular Biosciences, Graz, Austria; BioTechMed-Graz, Graz, Austria; Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Bastian Daniel
- Graz University of Technology, NAWI Graz, Institute of Biochemistry, Graz, Austria; University of Graz, NAWI Graz, Institute of Molecular Biosciences, Graz, Austria; Acib-Austrian Centre of Industrial Biotechnology, Krenngasse 37, Graz, Austria.
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4
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Gandomkar S, Jost E, Loidolt D, Swoboda A, Pickl M, Elaily W, Daniel B, Fraaije MW, Macheroux P, Kroutil W. Biocatalytic Enantioselective Oxidation of Sec-Allylic Alcohols with Flavin-Dependent Oxidases. Adv Synth Catal 2019; 361:5264-5271. [PMID: 31894182 PMCID: PMC6919931 DOI: 10.1002/adsc.201900921] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/26/2019] [Indexed: 01/17/2023]
Abstract
The oxidation of allylic alcohols is challenging to perform in a chemo- as well as stereo-selective fashion at the expense of molecular oxygen using conventional chemical protocols. Here, we report the identification of a library of flavin-dependent oxidases including variants of the berberine bridge enzyme (BBE) analogue from Arabidopsis thaliana (AtBBE15) and the 5-(hydroxymethyl)furfural oxidase (HMFO) and its variants (V465T, V465S, V465T/W466H and V367R/W466F) for the enantioselective oxidation of sec-allylic alcohols. While primary and benzylic alcohols as well as certain sugars are well known to be transformed by flavin-dependent oxidases, sec-allylic alcohols have not been studied yet except in a single report. The model substrates investigated were oxidized enantioselectively in a kinetic resolution with an E-value of up to >200. For instance HMFO V465S/T oxidized the (S)-enantiomer of (E)-oct-3-en-2-ol (1 a) and (E)-4-phenylbut-3-en-2-ol with E>200 giving the remaining (R)-alcohol with ee>99% at 50% conversion. The enantioselectivity could be decreased if required by medium engineering by the addition of cosolvents (e. g. dimethyl sulfoxide).
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Affiliation(s)
- Somayyeh Gandomkar
- Institute of Chemistry, NAWI Graz, BioTechMed GrazUniversity of GrazHeinrichstr. 288010GrazAustria
| | - Etta Jost
- Institute of Chemistry, NAWI Graz, BioTechMed GrazUniversity of GrazHeinrichstr. 288010GrazAustria
| | - Doris Loidolt
- Institute of Chemistry, NAWI Graz, BioTechMed GrazUniversity of GrazHeinrichstr. 288010GrazAustria
| | - Alexander Swoboda
- Institute of Chemistry, NAWI Graz, BioTechMed GrazUniversity of GrazHeinrichstr. 288010GrazAustria
| | - Mathias Pickl
- Institute of Chemistry, NAWI Graz, BioTechMed GrazUniversity of GrazHeinrichstr. 288010GrazAustria
| | - Wael Elaily
- Institute of BiochemistryGraz University of TechnologyPetersgasse 12/II8010GrazAustria
- Chemistry of Natural & Microbial Products DepartmentNational Research Centre33 El Buhouth St12622CairoEgypt
| | - Bastian Daniel
- Institute of BiochemistryGraz University of TechnologyPetersgasse 12/II8010GrazAustria
- Austrian Centre of Industrial Biotechnology, c/o Institute of Molecular BiosciencesUniversity of GrazHumboldtstraße 508010GrazAustria
| | - Marco W. Fraaije
- Molecular Enzymology GroupUniversity of GroningenNijenborgh 49747AGGroningenThe Netherlands
| | - Peter Macheroux
- Institute of BiochemistryGraz University of TechnologyPetersgasse 12/II8010GrazAustria
| | - Wolfgang Kroutil
- Institute of Chemistry, NAWI Graz, BioTechMed GrazUniversity of GrazHeinrichstr. 288010GrazAustria
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Toplak M, Wiedemann G, Ulićević J, Daniel B, Hoernstein SNW, Kothe J, Niederhauser J, Reski R, Winkler A, Macheroux P. The single berberine bridge enzyme homolog of Physcomitrella patens is a cellobiose oxidase. FEBS J 2018; 285:1923-1943. [PMID: 29633551 PMCID: PMC6001459 DOI: 10.1111/febs.14458] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 03/17/2018] [Accepted: 03/29/2018] [Indexed: 11/28/2022]
Abstract
The berberine bridge enzyme from the California poppy Eschscholzia californica (EcBBE) catalyzes the oxidative cyclization of (S)‐reticuline to (S)‐scoulerine, that is, the formation of the berberine bridge in the biosynthesis of benzylisoquinoline alkaloids. Interestingly, a large number of BBE‐like genes have been identified in plants that lack alkaloid biosynthesis. This finding raised the question of the primordial role of BBE in the plant kingdom, which prompted us to investigate the closest relative of EcBBE in Physcomitrella patens (PpBBE1), the most basal plant harboring a BBE‐like gene. Here, we report the biochemical, structural, and in vivo characterization of PpBBE1. Our studies revealed that PpBBE1 is structurally and biochemically very similar to EcBBE. In contrast to EcBBE, we found that PpBBE1 catalyzes the oxidation of the disaccharide cellobiose to the corresponding lactone, that is, PpBBE1 is a cellobiose oxidase. The enzymatic reaction mechanism was characterized by a structure‐guided mutagenesis approach that enabled us to assign a catalytic role to amino acid residues in the active site of PpBBE1. In vivo experiments revealed the highest level of PpBBE1 expression in chloronema, the earliest stage of the plant's life cycle, where carbon metabolism is strongly upregulated. It was also shown that the enzyme is secreted to the extracellular space, where it may be involved in later steps of cellulose degradation, thereby allowing the moss to make use of cellulose for energy production. Overall, our results suggest that the primordial role of BBE‐like enzymes in plants revolved around primary metabolic reactions in carbohydrate utilization. Database Structural data are available in the PDB under the accession numbers 6EO4 and 6EO5.
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Affiliation(s)
- Marina Toplak
- Institute of Biochemistry, Graz University of Technology, Austria
| | - Gertrud Wiedemann
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Germany
| | - Jelena Ulićević
- Institute of Biochemistry, Graz University of Technology, Austria
| | - Bastian Daniel
- Institute of Biochemistry, Graz University of Technology, Austria
| | | | - Jennifer Kothe
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Germany
| | | | - Ralf Reski
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Germany
| | - Andreas Winkler
- Institute of Biochemistry, Graz University of Technology, Austria
| | - Peter Macheroux
- Institute of Biochemistry, Graz University of Technology, Austria
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6
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The family of berberine bridge enzyme-like enzymes: A treasure-trove of oxidative reactions. Arch Biochem Biophys 2017; 632:88-103. [PMID: 28676375 DOI: 10.1016/j.abb.2017.06.023] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/29/2017] [Accepted: 06/30/2017] [Indexed: 12/18/2022]
Abstract
Biological oxidations form the basis of life on earth by utilizing organic compounds as electron donors to drive the generation of metabolic energy carriers, such as ATP. Oxidative reactions are also important for the biosynthesis of complex compounds, i.e. natural products such as alkaloids that provide vital benefits for organisms in all kingdoms of life. The vitamin B2-derived cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) enable an astonishingly diverse array of oxidative reactions that is based on the versatility of the redox-active isoalloxazine ring. The family of FAD-linked oxidases can be divided into subgroups depending on specific sequence features in an otherwise very similar structural context. The sub-family of berberine bridge enzyme (BBE)-like enzymes has recently attracted a lot of attention due to the challenging chemistry catalyzed by its members and the unique and unusual bi-covalent attachment of the FAD cofactor. This family is the focus of the present review highlighting recent advancements into the structural and functional aspects of members from bacteria, fungi and plants. In view of the unprecedented reaction catalyzed by the family's namesake, BBE from the California poppy, recent studies have provided further insights into nature's treasure chest of oxidative reactions.
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