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Herzog PL, Borghi E, Traxlmayr MW, Obinger C, Sikes HD, Peterbauer CK. Developing a cell-bound detection system for the screening of oxidase activity using the fluorescent peroxide sensor roGFP2-Orp1. Protein Eng Des Sel 2020; 33:gzaa019. [PMID: 32930800 PMCID: PMC7720637 DOI: 10.1093/protein/gzaa019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 06/02/2020] [Accepted: 07/08/2020] [Indexed: 11/14/2022] Open
Abstract
Accurate yet efficient high-throughput screenings have emerged as essential technology for enzyme engineering via directed evolution. Modern high-throughput screening platforms for oxidoreductases are commonly assisted by technologies such as surface display and rely on emulsification techniques to facilitate single-cell analysis via fluorescence-activated cell sorting. Empowered by the dramatically increased throughput, the screening of significantly larger sequence spaces in acceptable time frames is achieved but usually comes at the cost of restricted applicability. In this work, we tackle this problem by utilizing roGFP2-Orp1 as a fluorescent one-component detection system for enzymatic H2O2 formation. We determined the kinetic parameters of the roGFP2-Orp1 reaction with H2O2 and established an efficient immobilization technique for the sensor on Saccharomyces cerevisiae cells employing the lectin Concanavalin A. This allowed to realize a peroxide-sensing shell on enzyme-displaying cells, a system that was successfully employed to screen for H2O2 formation of enzyme variants in a whole-cell setting.
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Affiliation(s)
- P L Herzog
- Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU – University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria
| | - E Borghi
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Giuseppe Campi 287, 41124 Modena, Italy
| | - M W Traxlmayr
- Institute of Biochemistry, Department of Chemistry, BOKU – University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - C Obinger
- Institute of Biochemistry, Department of Chemistry, BOKU – University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - H D Sikes
- Department of Chemical Engineering, MIT – Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge 02139, MA, USA
| | - C K Peterbauer
- Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU – University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria
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Peterbauer CK. Pyranose dehydrogenases: Rare enzymes for electrochemistry and biocatalysis. Bioelectrochemistry 2020; 132:107399. [DOI: 10.1016/j.bioelechem.2019.107399] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/26/2019] [Accepted: 09/26/2019] [Indexed: 10/25/2022]
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Brugger D, Krondorfer I, Zahma K, Stoisser T, Bolivar JM, Nidetzky B, Peterbauer CK, Haltrich D. Convenient microtiter plate-based, oxygen-independent activity assays for flavin-dependent oxidoreductases based on different redox dyes. Biotechnol J 2014; 9:474-82. [PMID: 24376171 PMCID: PMC4162990 DOI: 10.1002/biot.201300336] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 11/01/2013] [Accepted: 12/17/2013] [Indexed: 11/06/2022]
Abstract
Flavin-dependent oxidoreductases are increasingly recognized as important biocatalysts for various industrial applications. In order to identify novel activities and to improve these enzymes in engineering approaches, suitable screening methods are necessary. We developed novel microtiter-plate-based assays for flavin-dependent oxidases and dehydrogenases using redox dyes as electron acceptors for these enzymes. 2,6-dichlorophenol-indophenol, methylene green, and thionine show absorption changes between their oxidized and reduced forms in the visible range, making it easy to judge visually changes in activity. A sample set of enzymes containing both flavoprotein oxidases and dehydrogenases - pyranose 2-oxidase, pyranose dehydrogenase, cellobiose dehydrogenase, D-amino acid oxidase, and L-lactate oxidase - was selected. Assays for these enzymes are based on a direct enzymatic reduction of the redox dyes and not on the coupled detection of a reaction product as in the frequently used assays based on hydrogen peroxide formation. The different flavoproteins show low Michaelis constants with these electron acceptor substrates, and therefore these dyes need to be added in only low concentrations to assure substrate saturation. In conclusion, these electron acceptors are useful in selective, reliable and cheap MTP-based screening assays for a range of flavin-dependent oxidoreductases, and offer a robust method for library screening, which could find applications in enzyme engineering programs.
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Affiliation(s)
- Dagmar Brugger
- Food Biotechnology Laboratory, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
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Tan TC, Spadiut O, Gandini R, Haltrich D, Divne C. Structural basis for binding of fluorinated glucose and galactose to Trametes multicolor pyranose 2-oxidase variants with improved galactose conversion. PLoS One 2014; 9:e86736. [PMID: 24466218 PMCID: PMC3897772 DOI: 10.1371/journal.pone.0086736] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 12/15/2013] [Indexed: 11/18/2022] Open
Abstract
Each year, about six million tons of lactose are generated from liquid whey as industrial byproduct, and optimally this large carbohydrate waste should be used for the production of value-added products. Trametes multicolor pyranose 2-oxidase (TmP2O) catalyzes the oxidation of various monosaccharides to the corresponding 2-keto sugars. Thus, a potential use of TmP2O is to convert the products from lactose hydrolysis, D-glucose and D-galactose, to more valuable products such as tagatose. Oxidation of glucose is however strongly favored over galactose, and oxidation of both substrates at more equal rates is desirable. Characterization of TmP2O variants (H450G, V546C, H450G/V546C) with improved D-galactose conversion has been given earlier, of which H450G displayed the best relative conversion between the substrates. To rationalize the changes in conversion rates, we have analyzed high-resolution crystal structures of the aforementioned mutants with bound 2- and 3-fluorinated glucose and galactose. Binding of glucose and galactose in the productive 2-oxidation binding mode is nearly identical in all mutants, suggesting that this binding mode is essentially unaffected by the mutations. For the competing glucose binding mode, enzyme variants carrying the H450G replacement stabilize glucose as the α-anomer in position for 3-oxidation. The backbone relaxation at position 450 allows the substrate-binding loop to fold tightly around the ligand. V546C however stabilize glucose as the β-anomer using an open loop conformation. Improved binding of galactose is enabled by subtle relaxation effects at key active-site backbone positions. The competing binding mode for galactose 2-oxidation by V546C stabilizes the β-anomer for oxidation at C1, whereas H450G variants stabilize the 3-oxidation binding mode of the galactose α-anomer. The present study provides a detailed description of binding modes that rationalize changes in the relative conversion rates of D-glucose and D-galactose and can be used to refine future enzyme designs for more efficient use of lactose-hydrolysis byproducts.
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Affiliation(s)
- Tien Chye Tan
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Oliver Spadiut
- School of Biotechnology, Royal Institute of Technology, Stockholm, Sweden
| | - Rosaria Gandini
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Dietmar Haltrich
- Food Biotechnology Laboratory, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
| | - Christina Divne
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden ; School of Biotechnology, Royal Institute of Technology, Stockholm, Sweden
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Salaheddin C, Takakura Y, Tsunashima M, Stranzinger B, Spadiut O, Yamabhai M, Peterbauer CK, Haltrich D. Characterisation of recombinant pyranose oxidase from the cultivated mycorrhizal basidiomycete Lyophyllum shimeji (hon-shimeji). Microb Cell Fact 2010; 9:57. [PMID: 20630076 PMCID: PMC2914677 DOI: 10.1186/1475-2859-9-57] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 07/14/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The flavin-dependent enzyme pyranose 2-oxidase (P2Ox) has gained increased attention during the last years because of a number of attractive applications for this enzyme. P2Ox is a unique biocatalyst with high potential for biotransformations of carbohydrates and in synthetic carbohydrate chemistry. Recently, it was shown that P2Ox is useful as bioelement in biofuel cells, replacing glucose oxidase (GOx), which traditionally is used in these applications. P2Ox offers several advantages over GOx for this application, e.g., its much broader substrate specificity. Because of this renewed interest in P2Ox, knowledge on novel pyranose oxidases isolated from organisms other than white-rot fungi, which represent the traditional source of this enzyme, is of importance, as these novel enzymes might differ in their biochemical and physical properties. RESULTS We isolated and over-expressed the p2ox gene encoding P2Ox from the ectomycorrhizal fungus Lyophyllum shimeji. The p2ox cDNA was inserted into the bacterial expression vector pET21a(+) and successfully expressed in E. coli Rosetta 2. We obtained active, flavinylated recombinant P2Ox in yields of approximately 130 mg per L of medium. The enzyme was purified by a two-step procedure based on anion exchange chromatography and preparative native PAGE, yielding an apparently homogenous enzyme preparation with a specific activity of 1.92 U/mg (using glucose and air oxygen as the substrates). Recombinant P2Ox from L. shimeji was characterized in some detail with respect to its physical and catalytic properties, and compared to the well-characterised enzymes from Phanerochaete chrysosporium and Trametes multicolor. CONCLUSION L. shimeji P2Ox shows properties that are comparable to those of P2Ox from white-rot fungal origin, and is in general characterised by lower K(m) and k(cat) values both for electron donor (sugar) as well as electron acceptor (ferrocenium ion, 1,4-benzoquinone, 2,6-dichloroindophenol). While L. shimeji P2Ox is the least thermostable of these three enzymes (melting temperature T(m) of 54.9 degrees C; half-life time of activity tau1/2 of 0.12 at 50 degrees C and pH 6.5), P. chrysosporium P2Ox showed remarkable thermostability with T(m) of 75.4 degrees C and tau1/2 of 96 h under identical conditions.
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Affiliation(s)
- Clara Salaheddin
- Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
- Research Centre Applied Biocatalysis, Graz, Austria
| | | | | | - Barbara Stranzinger
- Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
| | - Oliver Spadiut
- Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
| | - Montarop Yamabhai
- School of Biotechnology, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Clemens K Peterbauer
- Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
| | - Dietmar Haltrich
- Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
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Spadiut O, Nguyen TT, Haltrich D. Thermostable variants of pyranose 2-oxidase showing altered substrate selectivity for glucose and galactose. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:3465-71. [PMID: 20158200 DOI: 10.1021/jf9040047] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The homotetrameric flavoprotein pyranose 2-oxidase (P2Ox) has several proposed biotechnological applications, among others as a biocatalyst for carbohydrate transformations toward higher-value products. To improve some of the catalytic properties of P2Ox from Trametes multicolor, we selected a semirational enzyme engineering approach, namely, saturation mutagenesis of the amino acid His450 located at a pivotal point of the active site loop and subsequent screening of the libraries thus obtained for improved activity with the sugar substrate d-galactose. A variant with improved catalytic characteristics identified was H450G, which showed a significant, 3.6-fold decrease in K(M) together with a 1.4-fold increase in k(cat) for its substrate D-galactose and an overall improvement in the catalytic efficiency by a factor of 5. By combining H450G with other amino acid replacements, we obtained the P2Ox variants H450G/V546C and H450G/E542K/V546C, which can be of interest for applications in food industry due to their increased activity with D-galactose, high activity with D-glucose, and considerably increased stability for the latter variant. While the His-tagged recombinant wild-type enzyme strongly prefers D-glucose to D-galactose as its substrate, H450G/E542K/V546C converts both sugars, which are found in lactose hydrolysates, concomitantly, as was shown by laboratory-scale biotransformation experiments. The 2-keto sugars thus obtained can conveniently be reduced to the corresponding ketoses D-fructose and D-tagatose.
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Affiliation(s)
- Oliver Spadiut
- Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Applied Life Sciences, Vienna, Austria
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Pitsawong W, Sucharitakul J, Prongjit M, Tan TC, Spadiut O, Haltrich D, Divne C, Chaiyen P. A conserved active-site threonine is important for both sugar and flavin oxidations of pyranose 2-oxidase. J Biol Chem 2010; 285:9697-9705. [PMID: 20089849 DOI: 10.1074/jbc.m109.073247] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pyranose 2-oxidase (P2O) catalyzes the oxidation by O(2) of d-glucose and several aldopyranoses to yield the 2-ketoaldoses and H(2)O(2). Based on crystal structures, in one rotamer conformation, the threonine hydroxyl of Thr(169) forms H-bonds to the flavin-N5/O4 locus, whereas, in a different rotamer, it may interact with either sugar or other parts of the P2O.sugar complex. Transient kinetics of wild-type (WT) and Thr(169) --> S/N/G/A replacement variants show that D-Glc binds to T169S, T169N, and WT with the same K(d) (45-47 mm), and the hydride transfer rate constants (k(red)) are similar (15.3-9.7 s(-1) at 4 degrees C). k(red) of T169G with D-glucose (0.7 s(-1), 4 degrees C) is significantly less than that of WT but not as severely affected as in T169A (k(red) of 0.03 s(-1) at 25 degrees C). Transient kinetics of WT and mutants using d-galactose show that P2O binds d-galactose with a one-step binding process, different from binding of d-glucose. In T169S, T169N, and T169G, the overall turnover with d-Gal is faster than that of WT due to an increase of k(red). In the crystal structure of T169S, Ser(169) O gamma assumes a position identical to that of O gamma 1 in Thr(169); in T169G, solvent molecules may be able to rescue H-bonding. Our data suggest that a competent reductive half-reaction requires a side chain at position 169 that is able to form an H-bond within the ES complex. During the oxidative half-reaction, all mutants failed to stabilize a C4a-hydroperoxyflavin intermediate, thus suggesting that the precise position and geometry of the Thr(169) side chain are required for intermediate stabilization.
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Affiliation(s)
- Warintra Pitsawong
- Department of Biochemistry and Center of Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Jeerus Sucharitakul
- Department of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Henri-Dunant Road, Patumwan, Bangkok 10300, Thailand
| | - Methinee Prongjit
- Department of Biochemistry and Center of Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Tien-Chye Tan
- Division of Glycoscience, Kungliga Tekniska Högskolan Biotechnology, Royal Institute of Technology, Albanova University Center, SE-106 91 Stockholm, Sweden
| | - Oliver Spadiut
- Division of Glycoscience, Kungliga Tekniska Högskolan Biotechnology, Royal Institute of Technology, Albanova University Center, SE-106 91 Stockholm, Sweden
| | - Dietmar Haltrich
- Department of Food Science and Technology, Bodenkultur-University of Natural Resource and Applied Life Sciences, A-1190 Vienna, Austria
| | - Christina Divne
- Division of Glycoscience, Kungliga Tekniska Högskolan Biotechnology, Royal Institute of Technology, Albanova University Center, SE-106 91 Stockholm, Sweden
| | - Pimchai Chaiyen
- Department of Biochemistry and Center of Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
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Peterbauer CK, Volc J. Pyranose dehydrogenases: biochemical features and perspectives of technological applications. Appl Microbiol Biotechnol 2009; 85:837-48. [PMID: 19768457 DOI: 10.1007/s00253-009-2226-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 08/24/2009] [Accepted: 08/24/2009] [Indexed: 11/25/2022]
Abstract
Pyranose dehydrogenase is a fungal flavin-dependent sugar oxidoreductase which is structurally and catalytically related to fungal pyranose oxidase and cellobiose dehydrogenase and probably fulfills similar biological functions in lignocellulose breakdown. It is a monomeric secretory glycoprotein and is limited to a rather small group of litter-decomposing basidiomycetes. Compared with pyranose oxidase, it displays broader substrate specificity and a variable regioselectivity and is unable to utilize oxygen as electron acceptor using substituted benzoquinones and (organo) metallic ions instead. Depending on the structure of the sugar in pyranose form (mono/di/oligosaccharide or glycoside) and the enzyme source, selective monooxidations at C-1, C-2, C-3, or dioxidations at C-2,3 or C-3,4 of the molecule to the corresponding aldonolactones (C-1), or (di)dehydrosugars (aldos(di)uloses) can be performed. These features make pyranose dehydrogenase a promising and versatile biocatalyst for production of highly reactive, sometimes unique, di- and tri-carbonyl sugar derivatives that may serve as interesting chiral intermediates for the synthesis of rare sugars, novel drugs, and fine chemicals.
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Affiliation(s)
- Clemens K Peterbauer
- Department of Food Sciences and Technology, BOKU-University of Natural Resources and Applied Life Sciences, Vienna, Austria.
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