1
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Tong Y, Kaya SG, Russo S, Rozeboom HJ, Wijma HJ, Fraaije MW. Fixing Flavins: Hijacking a Flavin Transferase for Equipping Flavoproteins with a Covalent Flavin Cofactor. J Am Chem Soc 2023; 145:27140-27148. [PMID: 38048072 PMCID: PMC10722498 DOI: 10.1021/jacs.3c12009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 11/17/2023] [Accepted: 11/20/2023] [Indexed: 12/05/2023]
Abstract
Most flavin-dependent enzymes contain a dissociable flavin cofactor. We present a new approach for installing in vivo a covalent bond between a flavin cofactor and its host protein. By using a flavin transferase and carving a flavinylation motif in target proteins, we demonstrate that "dissociable" flavoproteins can be turned into covalent flavoproteins. Specifically, four different flavin mononucleotide-containing proteins were engineered to undergo covalent flavinylation: a light-oxygen-voltage domain protein, a mini singlet oxygen generator, a nitroreductase, and an old yellow enzyme-type ene reductase. Optimizing the flavinylation motif and expression conditions led to the covalent flavinylation of all four flavoproteins. The engineered covalent flavoproteins retained function and often exhibited improved performance, such as higher thermostability or catalytic performance. The crystal structures of the designed covalent flavoproteins confirmed the designed threonyl-phosphate linkage. The targeted flavoproteins differ in fold and function, indicating that this method of introducing a covalent flavin-protein bond is a powerful new method to create flavoproteins that cannot lose their cofactor, boosting their performance.
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Affiliation(s)
- Yapei Tong
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Saniye G. Kaya
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Sara Russo
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Henriette J. Rozeboom
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Hein J. Wijma
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Marco W. Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
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2
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Mouli MSSV, Mishra AK. Synthesis, characterization and photophysical studies of the flavopeptide conjugates as model for the covalently linked flavoenzymes. J CHEM SCI 2022. [DOI: 10.1007/s12039-022-02050-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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3
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Eggers R, Jammer A, Jha S, Kerschbaumer B, Lahham M, Strandback E, Toplak M, Wallner S, Winkler A, Macheroux P. The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana. PHYTOCHEMISTRY 2021; 189:112822. [PMID: 34118767 DOI: 10.1016/j.phytochem.2021.112822] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/23/2021] [Accepted: 05/24/2021] [Indexed: 06/12/2023]
Abstract
Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are utilized as coenzymes in many biochemical reduction-oxidation reactions owing to the ability of the tricyclic isoalloxazine ring system to employ the oxidized, radical and reduced state. We have analyzed the genome of Arabidopsis thaliana to establish an inventory of genes encoding flavin-dependent enzymes (flavoenzymes) as a basis to explore the range of flavin-dependent biochemical reactions that occur in this model plant. Expectedly, flavoenzymes catalyze many pivotal reactions in primary catabolism, which are connected to the degradation of basic metabolites, such as fatty and amino acids as well as carbohydrates and purines. On the other hand, flavoenzymes play diverse roles in anabolic reactions most notably the biosynthesis of amino acids as well as the biosynthesis of pyrimidines and sterols. Importantly, the role of flavoenzymes goes much beyond these basic reactions and extends into pathways that are equally crucial for plant life, for example the production of natural products. In this context, we outline the participation of flavoenzymes in the biosynthesis and maintenance of cofactors, coenzymes and accessory plant pigments (e. g. carotenoids) as well as phytohormones. Moreover, several multigene families have emerged as important components of plant immunity, for example the family of berberine bridge enzyme-like enzymes, flavin-dependent monooxygenases and NADPH oxidases. Furthermore, the versatility of flavoenzymes is highlighted by their role in reactions leading to tRNA-modifications, chromatin regulation and cellular redox homeostasis. The favorable photochemical properties of the flavin chromophore are exploited by photoreceptors to govern crucial processes of plant adaptation and development. Finally, a sequence- and structure-based approach was undertaken to gain insight into the catalytic role of uncharacterized flavoenzymes indicating their involvement in unknown biochemical reactions and pathways in A. thaliana.
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Affiliation(s)
- Reinmar Eggers
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Alexandra Jammer
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Shalinee Jha
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Bianca Kerschbaumer
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Majd Lahham
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Emilia Strandback
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Marina Toplak
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Silvia Wallner
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Andreas Winkler
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria
| | - Peter Macheroux
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010, Graz, Austria.
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4
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Discovery of fungal oligosaccharide-oxidising flavo-enzymes with previously unknown substrates, redox-activity profiles and interplay with LPMOs. Nat Commun 2021; 12:2132. [PMID: 33837197 PMCID: PMC8035211 DOI: 10.1038/s41467-021-22372-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 03/09/2021] [Indexed: 12/14/2022] Open
Abstract
Oxidative plant cell-wall processing enzymes are of great importance in biology and biotechnology. Yet, our insight into the functional interplay amongst such oxidative enzymes remains limited. Here, a phylogenetic analysis of the auxiliary activity 7 family (AA7), currently harbouring oligosaccharide flavo-oxidases, reveals a striking abundance of AA7-genes in phytopathogenic fungi and Oomycetes. Expression of five fungal enzymes, including three from unexplored clades, expands the AA7-substrate range and unveils a cellooligosaccharide dehydrogenase activity, previously unknown within AA7. Sequence and structural analyses identify unique signatures distinguishing the strict dehydrogenase clade from canonical AA7 oxidases. The discovered dehydrogenase directly is able to transfer electrons to an AA9 lytic polysaccharide monooxygenase (LPMO) and fuel cellulose degradation by LPMOs without exogenous reductants. The expansion of redox-profiles and substrate range highlights the functional diversity within AA7 and sets the stage for harnessing AA7 dehydrogenases to fine-tune LPMO activity in biotechnological conversion of plant feedstocks. Microbial oxidoreductases are key in biomass breakdown. Here, the authors expand the specificity and redox scope within fungal auxiliary activity 7 family (AA7) enzymes and show that AA7 oligosaccharide dehydrogenases can directly fuel cellulose degradation by lytic polysaccharide monooxygenases.
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5
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Iyer A, Reis RAG, Gannavaram S, Momin M, Spring-Connell AM, Orozco-Gonzalez Y, Agniswamy J, Hamelberg D, Weber IT, Gozem S, Wang S, Germann MW, Gadda G. A Single-Point Mutation in d-Arginine Dehydrogenase Unlocks a Transient Conformational State Resulting in Altered Cofactor Reactivity. Biochemistry 2021; 60:711-724. [PMID: 33630571 DOI: 10.1021/acs.biochem.1c00054] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Proteins are inherently dynamic, and proper enzyme function relies on conformational flexibility. In this study, we demonstrated how an active site residue changes an enzyme's reactivity by modulating fluctuations between conformational states. Replacement of tyrosine 249 (Y249) with phenylalanine in the active site of the flavin-dependent d-arginine dehydrogenase yielded an enzyme with both an active yellow FAD (Y249F-y) and an inactive chemically modified green FAD, identified as 6-OH-FAD (Y249F-g) through various spectroscopic techniques. Structural investigation of Y249F-g and Y249F-y variants by comparison to the wild-type enzyme showed no differences in the overall protein structure and fold. A closer observation of the active site of the Y249F-y enzyme revealed an alternative conformation for some active site residues and the flavin cofactor. Molecular dynamics simulations probed the alternate conformations observed in the Y249F-y enzyme structure and showed that the enzyme variant with FAD samples a metastable conformational state, not available to the wild-type enzyme. Hybrid quantum/molecular mechanical calculations identified differences in flavin electronics between the wild type and the alternate conformation of the Y249F-y enzyme. The computational studies further indicated that the alternate conformation in the Y249F-y enzyme is responsible for the higher spin density at the C6 atom of flavin, which is consistent with the formation of 6-OH-FAD in the variant enzyme. The observations in this study are consistent with an alternate conformational space that results in fine-tuning the microenvironment around a versatile cofactor playing a critical role in enzyme function.
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Affiliation(s)
- Archana Iyer
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Renata A G Reis
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Swathi Gannavaram
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Mohamed Momin
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | | | | | - Johnson Agniswamy
- Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States
| | - Donald Hamelberg
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Irene T Weber
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States
| | - Samer Gozem
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Siming Wang
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Markus W Germann
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States
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6
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Savino S, Fraaije MW. The vast repertoire of carbohydrate oxidases: An overview. Biotechnol Adv 2020; 51:107634. [PMID: 32961251 DOI: 10.1016/j.biotechadv.2020.107634] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 08/12/2020] [Accepted: 09/06/2020] [Indexed: 01/01/2023]
Abstract
Carbohydrates are widely abundant molecules present in a variety of forms. For their biosynthesis and modification, nature has evolved a plethora of carbohydrate-acting enzymes. Many of these enzymes are of particular interest for biotechnological applications, where they can be used as biocatalysts or biosensors. Among the enzymes catalysing conversions of carbohydrates are the carbohydrate oxidases. These oxidative enzymes belong to different structural families and use different cofactors to perform the oxidation reaction of CH-OH bonds in carbohydrates. The variety of carbohydrate oxidases available in nature reflects their specificity towards different sugars and selectivity of the oxidation site. Thanks to their properties, carbohydrate oxidases have received a lot of attention in basic and applied research, such that nowadays their role in biotechnological processes is of paramount importance. In this review we provide an overview of the available knowledge concerning the known carbohydrate oxidases. The oxidases are first classified according to their structural features. After a description on their mechanism of action, substrate acceptance and characterisation, we report on the engineering of the different carbohydrate oxidases to enhance their employment in biocatalysis and biotechnology. In the last part of the review we highlight some practical applications for which such enzymes have been exploited.
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Affiliation(s)
- Simone Savino
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG Groningen, the Netherlands
| | - Marco W Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG Groningen, the Netherlands.
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7
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Chen SC, Yen TM, Chang TH, Liaw SH. Evolution of archaeal Rib7 and eubacterial RibG reductases in riboflavin biosynthesis: Substrate specificity and cofactor preference. Biochem Biophys Res Commun 2018; 503:195-201. [PMID: 29864427 DOI: 10.1016/j.bbrc.2018.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 06/01/2018] [Indexed: 10/14/2022]
Abstract
Archaeal/fungal Rib7 and eubacterial RibG possess a reductase domain for ribosyl reduction in the second and third steps, respectively, of riboflavin biosynthesis. These enzymes are specific for an amino and a carbonyl group of the pyrimidine ring, respectively. Here, several crystal structures of Methanosarcina mazei Rib7 are reported at 2.27-1.95 Å resolution, which are the first archaeal dimeric Rib7 structures. Mutational analysis displayed that no detectable activity was observed for the Bacillus subtilis RibG K151A, K151D, and K151E mutants, and the M. mazei Rib7 D33N, D33K, and E156Q variants, while 0.1-0.6% of the activity was detected for the M. mazei Rib7 N9A, S29A, D33A, and D57N variants. Our results suggest that Lys151 in B. subtilis RibG, while Asp33 together with Arg36 in M. mazei Rib7, ensure the specific substrate recognition. Unexpectedly, an endogenous NADPH cofactor is observed in M. mazei Rib7, in which the 2'-phosphate group interacts with Ser88, and Arg91. Replacement of Ser88 with glutamate eliminates the endogenous NADPH binding and switches preference to NADH. The lower melting temperature of ∼10 °C for the S88E and R91A mutants suggests that nature had evolved a tightly bound NADPH to greatly enhance the structural stability of archaeal Rib7.
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Affiliation(s)
- Sheng-Chia Chen
- Structural Biology Program, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei, 11221, Taiwan
| | - Te-Ming Yen
- Structural Biology Program, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei, 11221, Taiwan; Institute of Biochemistry and Molecular Biology, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei, 11221, Taiwan
| | - Ting-Hao Chang
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei, 11221, Taiwan
| | - Shwu-Huey Liaw
- Structural Biology Program, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei, 11221, Taiwan; Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei, 11221, Taiwan; Department of Medical Research and Education, Taipei Veterans General Hospital, No. 201, Sec. 2, Shipai Road, Beitou District, Taipei, 11217, Taiwan.
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8
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Romero E, Gómez Castellanos JR, Gadda G, Fraaije MW, Mattevi A. Same Substrate, Many Reactions: Oxygen Activation in Flavoenzymes. Chem Rev 2018; 118:1742-1769. [DOI: 10.1021/acs.chemrev.7b00650] [Citation(s) in RCA: 216] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Elvira Romero
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - J. Rubén Gómez Castellanos
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
| | - Giovanni Gadda
- Departments of Chemistry and Biology, Center for Diagnostics and Therapeutics, and Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Marco W. Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Andrea Mattevi
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
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9
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Dourado DFAR, Swart M, Carvalho ATP. Why the Flavin Adenine Dinucleotide (FAD) Cofactor Needs To Be Covalently Linked to Complex II of the Electron-Transport Chain for the Conversion of FADH 2 into FAD. Chemistry 2017; 24:5246-5252. [PMID: 29124817 PMCID: PMC5969107 DOI: 10.1002/chem.201704622] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/07/2017] [Indexed: 11/10/2022]
Abstract
A covalently bound flavin cofactor is predominant in the succinate‐ubiquinone oxidoreductase (SQR; Complex II), an essential component of aerobic electron transport, and in the menaquinol‐fumarate oxidoreductase (QFR), the anaerobic counterpart, although it is only present in approximately 10 % of the known flavoenzymes. This work investigates the role of this 8α‐N3‐histidyl linkage between the flavin adenine dinucleotide (FAD) cofactor and the respiratory Complex II. After parameterization with DFT calculations, classical molecular‐dynamics simulations and quantum‐mechanics calculations for Complex II:FAD and Complex II:FADH2, with and without the covalent bond, were performed. It was observed that the covalent bond is essential for the active‐center arrangement of the FADH2/FAD cofactor. Removal of this bond causes a displacement of the isoalloxazine group, which influences interactions with the protein, flavin solvation, and possible proton‐transfer pathways. Specifically, for the noncovalently bound FADH2 cofactor, the N1 atom moves away from the His‐A365 and His‐A254 residues and the N5 atom moves away from the glutamine‐62A residue. Both of the histidine and glutamine residues interact with a chain of water molecules that cross the enzyme, which is most likely involved in proton transfer. Breaking this chain of water molecules could thereby compromise proton transfer across the two active sites of Complex II.
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Affiliation(s)
- Daniel F A R Dourado
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, Northern Ireland, UK.,Almac Sciences, Department of Biocatalysis and Isotope Chemistry, Almac House, 20 Seagoe Industrial Estate, Craigavon, BT63 5QD, Northern Ireland, UK
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, 17003, Girona, Spain.,ICREA, Pg. Lluís Companys 23, 08010, Barcelona, Spain
| | - Alexandra T P Carvalho
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
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10
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Su D, Yuan H, Gadda G. A Reversible, Charge-Induced Intramolecular C4a-S-Cysteinyl-Flavin in Choline Oxidase Variant S101C. Biochemistry 2017; 56:6677-6690. [DOI: 10.1021/acs.biochem.7b00958] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dan Su
- Department
of Chemistry, ‡Department of Biology, §Center for Diagnostics and Therapeutics, and ∥Center for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302, United States
| | - Hongling Yuan
- Department
of Chemistry, ‡Department of Biology, §Center for Diagnostics and Therapeutics, and ∥Center for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302, United States
| | - Giovanni Gadda
- Department
of Chemistry, ‡Department of Biology, §Center for Diagnostics and Therapeutics, and ∥Center for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302, United States
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11
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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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12
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Vuong TV, Foumani M, MacCormick B, Kwan R, Master ER. Direct comparison of gluco-oligosaccharide oxidase variants and glucose oxidase: substrate range and H 2O 2 stability. Sci Rep 2016; 6:37356. [PMID: 27869125 PMCID: PMC5116756 DOI: 10.1038/srep37356] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/27/2016] [Indexed: 12/01/2022] Open
Abstract
Glucose oxidase (GO) activity is generally restricted to glucose and is susceptible to inactivation by H2O2. By comparison, the Y300A variant of gluco-oligosaccharide oxidase (GOOX) from Sarocladium strictum showed broader substrate range and higher H2O2 stability. Specifically, Y300A exhibited up to 40 times higher activity on all tested sugars except glucose, compared to GO. Moreover, fusion of the Y300A variant to a family 22 carbohydrate binding module from Clostridium thermocellum (CtCBM22A) nearly doubled its catalytic efficiency on glucose, while retaining significant activity on oligosaccharides. In the presence of 200 mM of H2O2, the recombinant CtCBM22A_Y300A retained 80% of activity on glucose and 100% of activity on cellobiose, the preferred substrate for this enzyme. By contrast, a commercial glucose oxidase reported to contain ≤0.1 units catalase/ mg protein, retained 60% activity on glucose under the same conditions. GOOX variants appear to undergo a different mechanism of inactivation, as a loss of histidine instead of methionine was observed after H2O2 incubation. The addition of CtCBM22A also promoted functional binding of the fusion enzyme to xylan, facilitating its simultaneous purification and immobilization using edible oat spelt xylan, which might benefit the usage of this enzyme preparation in food and baking applications.
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Affiliation(s)
- Thu V Vuong
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada
| | - Maryam Foumani
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada
| | - Benjamin MacCormick
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada
| | - Rachel Kwan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada
| | - Emma R Master
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada
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13
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Ferrari AR, Rozeboom HJ, Dobruchowska JM, van Leeuwen SS, Vugts ASC, Koetsier MJ, Visser J, Fraaije MW. Discovery of a Xylooligosaccharide Oxidase from Myceliophthora thermophila C1. J Biol Chem 2016; 291:23709-23718. [PMID: 27629413 PMCID: PMC5095424 DOI: 10.1074/jbc.m116.741173] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/12/2016] [Indexed: 11/06/2022] Open
Abstract
By inspection of the predicted proteome of the fungus Myceliophthora thermophila C1 for vanillyl-alcohol oxidase (VAO)-type flavoprotein oxidases, a putative oligosaccharide oxidase was identified. By homologous expression and subsequent purification, the respective protein could be obtained. The protein was found to contain a bicovalently bound FAD cofactor. By screening a large number of carbohydrates, several mono- and oligosaccharides could be identified as substrates. The enzyme exhibits a strong substrate preference toward xylooligosaccharides; hence it is named xylooligosaccharide oxidase (XylO). Chemical analyses of the product formed upon oxidation of xylobiose revealed that the oxidation occurs at C1, yielding xylobionate as product. By elucidation of several XylO crystal structures (in complex with a substrate mimic, xylose, and xylobiose), the residues that tune the unique substrate specificity and regioselectivity could be identified. The discovery of this novel oligosaccharide oxidase reveals that the VAO-type flavoprotein family harbors oxidases tuned for specific oligosaccharides. The unique substrate profile of XylO hints at a role in the degradation of xylan-derived oligosaccharides by the fungus M. thermophila C1.
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Affiliation(s)
| | | | - Justyna M Dobruchowska
- Microbial Physiology Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen
| | - Sander S van Leeuwen
- Microbial Physiology Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen
| | | | | | - Jaap Visser
- the Fungal Genetics and Technology Consultancy, 6700 AJ Wageningen, The Netherlands
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14
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Teufel R, Agarwal V, Moore BS. Unusual flavoenzyme catalysis in marine bacteria. Curr Opin Chem Biol 2016; 31:31-9. [PMID: 26803009 DOI: 10.1016/j.cbpa.2016.01.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 01/08/2016] [Accepted: 01/08/2016] [Indexed: 11/27/2022]
Abstract
Ever since the discovery of the flavin cofactor more than 80 years ago, flavin-dependent enzymes have emerged as ubiquitous and versatile redox catalysts in primary metabolism. Yet, the recent advances in the discovery and characterization of secondary metabolic pathways exposed new roles for flavin-mediated catalysis in the generation of structurally complex natural products. Here, we review a selection of key biosynthetic flavoenzymes from marine bacterial secondary metabolism and illustrate how their functional and mechanistic investigation expanded our view of the cofactor's chemical repertoire and led to the discovery of a previously unknown flavin redox state.
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Affiliation(s)
- Robin Teufel
- ZBSA, Center for Biological Systems Analysis, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Vinayak Agarwal
- Center for Oceans and Human Health, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
| | - Bradley S Moore
- Center for Oceans and Human Health, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA; Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093, USA.
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15
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Lange K, Schmid A, Julsing MK. Δ9-Tetrahydrocannabinolic acid synthase production in Pichia pastoris enables chemical synthesis of cannabinoids. J Biotechnol 2015. [DOI: 10.1016/j.jbiotec.2015.06.425] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Kopacz MM, Fraaije MW. Turning a monocovalent flavoprotein into a bicovalent flavoprotein by structure-inspired mutagenesis. Bioorg Med Chem 2014; 22:5621-7. [DOI: 10.1016/j.bmc.2014.05.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 05/21/2014] [Accepted: 05/22/2014] [Indexed: 10/25/2022]
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17
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Fusion of a xylan-binding module to gluco-oligosaccharide oxidase increases activity and promotes stable immobilization. PLoS One 2014; 9:e95170. [PMID: 24736604 PMCID: PMC3988151 DOI: 10.1371/journal.pone.0095170] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/24/2014] [Indexed: 11/19/2022] Open
Abstract
The xylan-binding module Clostridium thermocellum CBM22A was successfully fused to a gluco-oligosaccharide oxidase, GOOX-VN, from Sarocladium strictum via a short TP linker, allowing the fused protein to effectively bind different xylans. The presence of the CtCBM22A at the N-terminal of GOOX-VN increased catalytic activity on mono- and oligo-saccharides by 2-3 fold while not affecting binding affinity to these substrates. Notably, both GOOX-VN and its CBM fusion also showed oxidation of xylo-oligosaccharides with degrees of polymerization greater than six. Whereas fusion to CtCBM22A did not alter the thermostability of GOOX-VN or reduce substrate inhibition, CtCBM22A_GOOX-VN could be immobilized to insoluble oat spelt xylan while retaining wild-type activity. QCM-D analysis showed that the fused enzyme remained bound during oxidation. These features could be harnessed to generate hemicellulose-based biosensors that detect and quantify the presence of different oligosaccharides.
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18
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Vuong TV, Vesterinen AH, Foumani M, Juvonen M, Seppälä J, Tenkanen M, Master ER. Xylo- and cello-oligosaccharide oxidation by gluco-oligosaccharide oxidase from Sarocladium strictum and variants with reduced substrate inhibition. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:148. [PMID: 24119501 PMCID: PMC4015748 DOI: 10.1186/1754-6834-6-148] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 10/04/2013] [Indexed: 05/21/2023]
Abstract
BACKGROUND The oxidation of carbohydrates from lignocellulose can facilitate the synthesis of new biopolymers and biochemicals, and also reduce sugar metabolism by lignocellulolytic microorganisms, reserving aldonates for fermentation to biofuels. Although oxidoreductases that oxidize cellulosic hydrolysates have been well characterized, none have been reported to oxidize substituted or branched xylo-oligosaccharides. Moreover, this is the first report that identifies amino acid substitutions leading to GOOX variants with reduced substrate inhibition. RESULTS The recombinant wild type gluco-oligosaccharide oxidase (GOOX) from the fungus Sarocladium strictum, along with variants that were generated by site-directed mutagenesis, retained the FAD cofactor, and showed high activity on cello-oligosaccharide and xylo-oligosaccharides, including substituted and branched xylo-oligosaccharides. Mass spectrometric analyses confirmed that GOOX introduces one oxygen atom to oxidized products, and 1H NMR and tandem mass spectrometry analysis confirmed that oxidation was restricted to the anomeric carbon. The A38V mutation, which is close to a predicted divalent ion-binding site in the FAD-binding domain of GOOX but 30 Å away from the active site, significantly increased the kcat and catalytic efficiency of the enzyme on all oligosaccharides. Eight amino acid substitutions were separately introduced to the substrate-binding domain of GOOX-VN (at positions Y72, E247, W351, Q353 and Q384). In all cases, the Km of the enzyme variant was higher than that of GOOX, supporting the role of corresponding residues in substrate binding. Most notably, W351A increased Km values by up to two orders of magnitude while also increasing kcat up to 3-fold on cello- and xylo-oligosaccharides and showing no substrate inhibition. CONCLUSIONS This study provides further evidence that S. strictum GOOX has broader substrate specificity than the enzyme name implies, and that substrate inhibition can be reduced by removing aromatic side chains in the -2 binding subsite. Of the enzyme variants, W351A might be particularly advantageous when oxidizing oligosaccharides present at high substrate concentrations often experienced in industrial processes.
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Affiliation(s)
- Thu V Vuong
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada
| | - Arja-Helena Vesterinen
- Department of Biotechnology and Chemical Technology, Aalto University, Kemistintie 1 D1, Espoo 02150, Finland
| | - Maryam Foumani
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada
| | - Minna Juvonen
- Department of Food and Environmental Sciences, University of Helsinki, P.O. Box 27, Helsinki 00014, Finland
| | - Jukka Seppälä
- Department of Biotechnology and Chemical Technology, Aalto University, Kemistintie 1 D1, Espoo 02150, Finland
| | - Maija Tenkanen
- Department of Food and Environmental Sciences, University of Helsinki, P.O. Box 27, Helsinki 00014, Finland
| | - Emma R Master
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada
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19
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Prokaryotic assembly factors for the attachment of flavin to complex II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:637-47. [PMID: 22985599 DOI: 10.1016/j.bbabio.2012.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 09/05/2012] [Accepted: 09/07/2012] [Indexed: 01/01/2023]
Abstract
Complex II (also known as Succinate dehydrogenase or Succinate-ubiquinone oxidoreductase) is an important respiratory enzyme that participates in both the tricarboxylic acid cycle and electron transport chain. Complex II consists of four subunits including a catalytic flavoprotein (SdhA), an iron-sulphur subunit (SdhB) and two hydrophobic membrane anchors (SdhC and SdhD). Complex II also contains a number of redox cofactors including haem, Fe-S clusters and FAD, which mediate electron transfer from succinate oxidation to the reduction of the mobile electron carrier ubiquinone. The flavin cofactor FAD is an important redox cofactor found in many proteins that participate in oxidation/reduction reactions. FAD is predominantly bound non-covalently to flavoproteins, with only a small percentage of flavoproteins, such as complex II, binding FAD covalently. Aside from a few examples, the mechanisms of flavin attachment have been a relatively unexplored area. This review will discuss the FAD cofactor and the mechanisms used by flavoproteins to covalently bind FAD. Particular focus is placed on the attachment of FAD to complex II with an emphasis on SdhE (a DUF339/SDH5 protein previously termed YgfY), the first protein identified as an assembly factor for FAD attachment to flavoproteins in prokaryotes. The molecular details of SdhE-dependent flavinylation of complex II are discussed and comparisons are made to known cofactor chaperones. Furthermore, an evolutionary hypothesis is proposed to explain the distribution of SdhE homologues in bacterial and eukaryotic species. Mechanisms for regulating SdhE function and how this may be linked to complex II function in different bacterial species are also discussed. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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20
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Wallner S, Winkler A, Riedl S, Dully C, Horvath S, Gruber K, Macheroux P. Catalytic and structural role of a conserved active site histidine in berberine bridge enzyme. Biochemistry 2012; 51:6139-47. [PMID: 22757961 PMCID: PMC3413249 DOI: 10.1021/bi300411n] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Berberine bridge enzyme (BBE) is a paradigm for the class
of bicovalently
flavinylated oxidases, which catalyzes the oxidative cyclization of
(S)-reticuline to (S)-scoulerine.
His174 was identified as an important active site residue because
of its role in the stabilization of the reduced state of the flavin
cofactor. It is also strictly conserved in the family of BBE-like
oxidases. Here, we present a detailed biochemical and structural characterization
of a His174Ala variant supporting its importance during catalysis
and for the structural organization of the active site. Substantial
changes in all kinetic parameters and a decrease in midpoint potential
were observed for the BBE His174Ala variant protein. Moreover, the
crystal structure of the BBE His174Ala variant showed significant
structural rearrangements compared to wild-type enzyme. On the basis
of our findings, we propose that His174 is part of a hydrogen bonding
network that stabilizes the negative charge at the N1–C2=O
locus via interaction with the hydroxyl group at C2′ of the
ribityl side chain of the flavin cofactor. Hence, replacement of this
residue with alanine reduces the stabilizing effect for the transiently
formed negative charge and results in drastically decreased kinetic
parameters as well as a lower midpoint redox potential.
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Affiliation(s)
- Silvia Wallner
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, A-8010 Graz, Austria
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21
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Carlson JC, Li S, Gunatilleke SS, Anzai Y, Burr DA, Podust LM, Sherman DH. Tirandamycin biosynthesis is mediated by co-dependent oxidative enzymes. Nat Chem 2011; 3:628-33. [PMID: 21778983 PMCID: PMC3154026 DOI: 10.1038/nchem.1087] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 06/03/2011] [Indexed: 11/23/2022]
Abstract
Elucidation of natural product biosynthetic pathways provides important insights into the assembly of potent bioactive molecules, and expands access to unique enzymes able to selectively modify complex substrates. Here, we show full reconstitution, in vitro, of an unusual multi-step oxidative cascade for post-assembly-line tailoring of tirandamycin antibiotics. This pathway involves a remarkably versatile and iterative cytochrome P450 monooxygenase (TamI) and a flavin adenine dinucleotide-dependent oxidase (TamL), which act co-dependently through the repeated exchange of substrates. TamI hydroxylates tirandamycin C (TirC) to generate tirandamycin E (TirE), a previously unidentified tirandamycin intermediate. TirE is subsequently oxidized by TamL, giving rise to the ketone of tirandamycin D (TirD), after which a unique exchange back to TamI enables successive epoxidation and hydroxylation to afford, respectively, the final products tirandamycin A (TirA) and tirandamycin B (TirB). Ligand-free, substrate- and product-bound crystal structures of bicovalently flavinylated TamL oxidase reveal a likely mechanism for the C10 oxidation of TirE.
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Affiliation(s)
- Jacob C. Carlson
- Life Sciences Institute and Departments of Medicinal Chemistry, Microbiology & Immunology and Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Shengying Li
- Life Sciences Institute and Departments of Medicinal Chemistry, Microbiology & Immunology and Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Shamila S. Gunatilleke
- Department of Pathology and Sandler Center for Drug Discovery, University of California, San Francisco, California, 94158; USA
| | - Yojiro Anzai
- Life Sciences Institute and Departments of Medicinal Chemistry, Microbiology & Immunology and Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Douglas A. Burr
- Life Sciences Institute and Departments of Medicinal Chemistry, Microbiology & Immunology and Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Larissa M. Podust
- Department of Pathology and Sandler Center for Drug Discovery, University of California, San Francisco, California, 94158; USA
| | - David H. Sherman
- Life Sciences Institute and Departments of Medicinal Chemistry, Microbiology & Immunology and Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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22
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Noinaj N, Bosserman MA, Schickli MA, Piszczek G, Kharel MK, Pahari P, Buchanan SK, Rohr J. The crystal structure and mechanism of an unusual oxidoreductase, GilR, involved in gilvocarcin V biosynthesis. J Biol Chem 2011; 286:23533-43. [PMID: 21561854 PMCID: PMC3123116 DOI: 10.1074/jbc.m111.247833] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 04/29/2011] [Indexed: 01/04/2023] Open
Abstract
GilR is a recently identified oxidoreductase that catalyzes the terminal step of gilvocarcin V biosynthesis and is a unique enzyme that establishes the lactone core of the polyketide-derived gilvocarcin chromophore. Gilvocarcin-type compounds form a small distinct family of anticancer agents that are involved in both photo-activated DNA-alkylation and histone H3 cross-linking. High resolution crystal structures of apoGilR and GilR in complex with its substrate pregilvocarcin V reveals that GilR belongs to the small group of a relatively new type of the vanillyl-alcohol oxidase flavoprotein family characterized by bicovalently tethered cofactors. GilR was found as a dimer, with the bicovalently attached FAD cofactor mediated through His-65 and Cys-125. Subsequent mutagenesis and functional assays indicate that Tyr-445 may be involved in reaction catalysis and in mediating the covalent attachment of FAD, whereas Tyr-448 serves as an essential residue initiating the catalysis by swinging away from the active site to accommodate binding of the 6R-configured substrate and consequently abstracting the proton of the hydroxyl residue of the substrate hemiacetal 6-OH group. These studies lay the groundwork for future enzyme engineering to broaden the substrate specificity of this bottleneck enzyme of the gilvocarcin biosynthetic pathway for the development of novel anti-cancer therapeutics.
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Affiliation(s)
| | - Mary A. Bosserman
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536-0596 and
| | - M. Alexandra Schickli
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536-0596 and
| | | | - Madan K. Kharel
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536-0596 and
| | - Pallab Pahari
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536-0596 and
| | | | - Jürgen Rohr
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536-0596 and
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23
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Foumani M, Vuong TV, Master ER. Altered substrate specificity of the gluco-oligosaccharide oxidase from Acremonium strictum. Biotechnol Bioeng 2011; 108:2261-9. [PMID: 21455933 DOI: 10.1002/bit.23149] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 03/05/2011] [Accepted: 03/14/2011] [Indexed: 11/08/2022]
Abstract
A gluco-oligosaccharide oxidase (GOOX) from Acremonium strictum type strain CBS 346.70 was cloned and expressed in Pichia pastoris. The recombinant protein, GOOX-VN, contained fifteen amino acid substitutions compared with the previously reported A. strictum GOOX. These two enzymes share 97% sequence identity; however, only GOOX-VN oxidized xylose, galactose, and N-acetylglucosamine. Besides monosaccharides, GOOX-VN oxidized xylo-oligosaccharides, including xylobiose and xylotriose with similar catalytic efficiency as for cello-oligosaccharides. Of three mutant enzymes that were created in GOOX-VN to improve substrate specificity, Y300A and Y300N doubled kcat values for monosaccharide and oligosaccharide substrates. With this novel substrate specificity, GOOX-VN and its variants are particularly valuable for oxidative modification of cello- and xylo-oligosaccharides.
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Affiliation(s)
- Maryam Foumani
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, Canada M5S 3E5; telephone: +1-416-946-7861; fax: +1-416-978-8605
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24
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Arslan BK, Edmondson DE. Expression of zebrafish (Danio rerio) monoamine oxidase (MAO) in Pichia pastoris: purification and comparison with human MAO A and MAO B. Protein Expr Purif 2010; 70:290-7. [PMID: 20079438 DOI: 10.1016/j.pep.2010.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 12/02/2009] [Accepted: 01/04/2010] [Indexed: 10/20/2022]
Abstract
The expression, purification and characterization of zebrafish monoamine oxidase (zMAO) using the methylotropic yeast Pichia pastoris expression system is described. A 1L fermentation culture of Pichia pastoris containing the gene encoding zMAO under control of the methanol oxidase promotor expresses approximately 200mg of zMAO exhibiting 300 U of total activity. The enzyme is found in the mitochondrial fraction of the expression host and is purified in a 30% yield as a homogenous species with a M(r) of approximately 60,000 on SDS-PAGE and a mass of 58,525+/-40 Da from MALDI-TOF measurements. The zMAO preparation contains one mole of covalent flavin cofactor per mole of enzyme and exhibits >80% functionality. The covalent flavin exhibits fluorescence and EPR spectral properties consistent with known properties of 8 alpha-S-cysteinyl FAD. Chemical degradation of the flavin peptide results in the liberation of FAD. zMAO exhibits no immuno-chemical cross-reactivity with polyclonal anti-sera raised against human MAO A. The enzyme preparation exhibits reasonable thermostability up to a temperature of 30 degrees C. Benzylamine is oxidized with a k(cat) value of 4.7+/-0.1 min(-1) (K(m)=82+/-9 microM) and the enzyme oxidizes phenylethylamine with a k(cat) value of 204 min(-1) (K(m)=86+/-13 microM). The K(m) (O(2)) values determined for zMAO using either benzylamine or phenylethylamine as substrates ranges from 108(+/-5) to 140(+/-21)microM. The functional behavior of this teleost MAO relative to human MAO A and MAO B is discussed.
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Affiliation(s)
- Betül Kacar Arslan
- Department of Biochemistry, Emory University, Rollins Research Bldg., 1510 Clifton Road, Atlanta, GA 30322, USA
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25
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Winkler A, Motz K, Riedl S, Puhl M, Macheroux P, Gruber K. Structural and mechanistic studies reveal the functional role of bicovalent flavinylation in berberine bridge enzyme. J Biol Chem 2009; 284:19993-20001. [PMID: 19457868 DOI: 10.1074/jbc.m109.015727] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Berberine bridge enzyme (BBE) is a member of the recently discovered family of bicovalently flavinylated proteins. In this group of enzymes, the FAD cofactor is linked via its 8alpha-methyl group and the C-6 atom to conserved histidine and cysteine residues, His-104 and Cys-166 for BBE, respectively. 6-S-Cysteinylation has recently been shown to have a significant influence on the redox potential of the flavin cofactor; however, 8alpha-histidylation evaded a closer characterization due to extremely low expression levels upon substitution. Co-overexpression of protein disulfide isomerase improved expression levels and allowed isolation and purification of the H104A protein variant. To gain more insight into the functional role of the unusual dual mode of cofactor attachment, we solved the x-ray crystal structures of two mutant proteins, H104A and C166A BBE, each lacking one of the covalent linkages. Information from a structure of wild type enzyme in complex with the product of the catalyzed reaction is combined with the kinetic and structural characterization of the protein variants to demonstrate the importance of the bicovalent linkage for substrate binding and efficient oxidation. In addition, the redox potential of the flavin cofactor is enhanced additively by the dual mode of cofactor attachment. The reduced level of expression for the H104A mutant protein and the difficulty of isolating even small amounts of the protein variant with both linkages removed (H104A-C166A) also points toward a possible role of covalent flavinylation during protein folding.
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Affiliation(s)
- Andreas Winkler
- Institute of Biochemistry, Graz University of Technology, 8010 Graz, Austria
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26
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Heuts DPHM, Scrutton NS, McIntire WS, Fraaije MW. What's in a covalent bond? On the role and formation of covalently bound flavin cofactors. FEBS J 2009; 276:3405-27. [PMID: 19438712 DOI: 10.1111/j.1742-4658.2009.07053.x] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many enzymes use one or more cofactors, such as biotin, heme, or flavin. These cofactors may be bound to the enzyme in a noncovalent or covalent manner. Although most flavoproteins contain a noncovalently bound flavin cofactor (FMN or FAD), a large number have these cofactors covalently linked to the polypeptide chain. Most covalent flavin-protein linkages involve a single cofactor attachment via a histidyl, tyrosyl, cysteinyl or threonyl linkage. However, some flavoproteins contain a flavin that is tethered to two amino acids. In the last decade, many studies have focused on elucidating the mechanism(s) of covalent flavin incorporation (flavinylation) and the possible role(s) of covalent protein-flavin bonds. These endeavors have revealed that covalent flavinylation is a post-translational and self-catalytic process. This review presents an overview of the known types of covalent flavin bonds and the proposed mechanisms and roles of covalent flavinylation.
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Affiliation(s)
- Dominic P H M Heuts
- Laboratory of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
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27
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Quaye O, Cowins S, Gadda G. Contribution of flavin covalent linkage with histidine 99 to the reaction catalyzed by choline oxidase. J Biol Chem 2009; 284:16990-16997. [PMID: 19398559 DOI: 10.1074/jbc.m109.003715] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The FAD-dependent choline oxidase has a flavin cofactor covalently attached to the protein via histidine 99 through an 8alpha-N(3)-histidyl linkage. The enzyme catalyzes the four-electron oxidation of choline to glycine betaine, forming betaine aldehyde as an enzyme-bound intermediate. The variant form of choline oxidase in which the histidine residue has been replaced with asparagine was used to investigate the contribution of the 8alpha-N(3)-histidyl linkage of FAD to the protein toward the reaction catalyzed by the enzyme. Decreases of 10-fold and 30-fold in the k(cat)/K(m) and k(cat) values were observed as compared with wild-type choline oxidase at pH 10 and 25 degrees C, with no significant effect on k(cat)/K(O) using choline as substrate. Both the k(cat)/K(m) and k(cat) values increased with increasing pH to limiting values at high pH consistent with the participation of an unprotonated group in the reductive half-reaction and the overall turnover of the enzyme. The pH independence of both (D)(k(cat)/K(m)) and (D)k(cat), with average values of 9.2 +/- 3.3 and 7.4 +/- 0.5, respectively, is consistent with absence of external forward and reverse commitments to catalysis, and the chemical step of CH bond cleavage being rate-limiting for both the reductive half-reaction and the overall enzyme turnover. The temperature dependence of the (D)k(red) values suggests disruption of the preorganization in the asparagine variant enzyme. Altogether, the data presented in this study are consistent with the FAD-histidyl covalent linkage being important for the optimal positioning of the hydride ion donor and acceptor in the tunneling reaction catalyzed by choline oxidase.
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Affiliation(s)
- Osbourne Quaye
- From the Departments of Chemistry, Atlanta, Georgia 30302-4098
| | - Sharonda Cowins
- From the Departments of Chemistry, Atlanta, Georgia 30302-4098; Department of Chemistry, Albany State University, Albany, Georgia 31705
| | - Giovanni Gadda
- From the Departments of Chemistry, Atlanta, Georgia 30302-4098; Biology, Atlanta, Georgia 30302-4098; The Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia 30302-4098.
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