51
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Teze D, Hendrickx J, Dion M, Tellier C, Woods VL, Tran V, Sanejouand YH. Conserved Water Molecules in Family 1 Glycosidases: A DXMS and Molecular Dynamics Study. Biochemistry 2013; 52:5900-10. [DOI: 10.1021/bi400260b] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- David Teze
- UFIP, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes,
France
| | - Johann Hendrickx
- UFIP, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes,
France
| | - Michel Dion
- UFIP, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes,
France
| | - Charles Tellier
- UFIP, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes,
France
| | - Virgil L. Woods
- Department of Medicine, University of California−San Diego, 9500 Gilman
Drive, La Jolla, California 92093-0652, United States
| | - Vinh Tran
- UFIP, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes,
France
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52
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Angling for uniqueness in enzymatic preparation of glycosides. Biomolecules 2013; 3:334-50. [PMID: 24970171 PMCID: PMC4030847 DOI: 10.3390/biom3020334] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 05/23/2013] [Accepted: 06/03/2013] [Indexed: 02/06/2023] Open
Abstract
In the early days of biocatalysis, limitations of an enzyme modeled the enzymatic applications; nowadays the enzyme can be engineered to be suitable for the process requirements. This is a general bird's-eye view and as such cannot be specific for articulated situations found in different classes of enzymes or for selected enzymatic processes. As far as the enzymatic preparation of glycosides is concerned, recent scientific literature is awash with examples of uniqueness related to the features of the biocatalyst (yield, substrate specificity, regioselectivity, and resistance to a particular reaction condition). The invention of glycosynthases is just one of the aspects that has thrust forward the research in this field. Protein engineering, metagenomics and reaction engineering have led to the discovery of an expanding number of novel enzymes and to the setting up of new bio-based processes for the preparation of glycosides. In this review, new examples from the last decade are compiled with attention both to cases in which naturally present, as well as genetically inserted, characteristics of the catalysts make them attractive for biocatalysis.
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53
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Arab-Jaziri F, Bissaro B, Dion M, Saurel O, Harrison D, Ferreira F, Milon A, Tellier C, Fauré R, O’Donohue MJ. Engineering transglycosidase activity into a GH51 α-l-arabinofuranosidase. N Biotechnol 2013; 30:536-44. [DOI: 10.1016/j.nbt.2013.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 04/12/2013] [Accepted: 04/13/2013] [Indexed: 11/17/2022]
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54
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Improved transferase/hydrolase ratio through rational design of a family 1 β-glucosidase from Thermotoga neapolitana. Appl Environ Microbiol 2013; 79:3400-5. [PMID: 23524680 DOI: 10.1128/aem.00359-13] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Alkyl glycosides are attractive surfactants because of their high surface activity and good biodegradability and can be produced from renewable resources. Through enzymatic catalysis, one can obtain well-defined alkyl glycosides, something that is very difficult to do using conventional chemistry. However, there is a need for better enzymes to get a commercially feasible process. A thermostable β-glucosidase from the well-studied glycoside hydrolase family 1 from Thermotoga neapolitana, TnBgl1A, was mutated in an attempt to improve its value for synthesis of alkyl glycosides. This was done by rational design using prior knowledge from structural homologues together with a recently generated model of the enzyme in question. Three out of four studied mutations increased the hydrolytic reaction rate in an aqueous environment, while none displayed this property in the presence of an alcohol acceptor. This shows that even if the enzyme resides in a separate aqueous phase, the presence of an organic solvent has a great influence. We could also show that a single amino acid replacement in a less studied part of the aglycone subsite, N220F, improves the specificity for transglycosylation 7-fold and thereby increases the potential yield of alkyl glycoside from 17% to 58%.
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55
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Teze D, Dion M, Daligault F, Tran V, André-Miral C, Tellier C. Alkoxyamino glycoside acceptors for the regioselective synthesis of oligosaccharides using glycosynthases and transglycosidases. Bioorg Med Chem Lett 2013; 23:448-51. [DOI: 10.1016/j.bmcl.2012.11.065] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 11/13/2012] [Accepted: 11/18/2012] [Indexed: 12/01/2022]
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56
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Wu Y, Yuan S, Chen S, Wu D, Chen J, Wu J. Enhancing the production of galacto-oligosaccharides by mutagenesis of Sulfolobus solfataricus β-galactosidase. Food Chem 2012; 138:1588-95. [PMID: 23411285 DOI: 10.1016/j.foodchem.2012.11.052] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 11/06/2012] [Accepted: 11/09/2012] [Indexed: 01/30/2023]
Abstract
Galacto-oligosaccharides (GOS), an important class of functional food, are commonly produced from lactose using β-galactosidase. In the present study, β-galactosidase (LacS) from Sulfolobus solfataricus P2 was cloned and site-directed mutagenesis was performed to obtain two mutants, F359Q and F441Y. All of the wild-type enzyme and mutants were expressed in Escherichia coli BL21(DE3) and purified to homogeneity. The enzymatic properties and optimal condition for transglycosylation reaction of the enzymes were investigated in detail. Under their individual optimal conditions, yields of GOS could reach 50.9% for wild-type enzyme, 58.3% for F359Q, and 61.7% for F441Y. In addition, the potential mechanism for this enhancement was analysed.
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Affiliation(s)
- Yufei Wu
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Ave., Wuxi 214122, People's Republic of China
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57
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Shim JH, Chen HM, Rich JR, Goddard-Borger ED, Withers SG. Directed evolution of a -glycosidase from Agrobacterium sp. to enhance its glycosynthase activity toward C3-modified donor sugars. Protein Eng Des Sel 2012; 25:465-72. [DOI: 10.1093/protein/gzs045] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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58
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Sandoval M, Ferreras E, Pérez-Sánchez M, Berenguer J, Sinisterra JV, Hernaiz MJ. Screening of strains and recombinant enzymes from Thermus thermophilus for their use in disaccharide synthesis. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.molcatb.2011.09.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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59
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Gänzle MG. Enzymatic synthesis of galacto-oligosaccharides and other lactose derivatives (hetero-oligosaccharides) from lactose. Int Dairy J 2012. [DOI: 10.1016/j.idairyj.2011.06.010] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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60
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Roy B, Ferdjani S, Tellier C, Rabiller C. Novel and convergent synthesis of modified glycosphingolipids, galactosyl-5-aza-sphinganines, by a diversity-oriented method. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.05.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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61
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Strohmeier GA, Pichler H, May O, Gruber-Khadjawi M. Application of Designed Enzymes in Organic Synthesis. Chem Rev 2011; 111:4141-64. [DOI: 10.1021/cr100386u] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Gernot A. Strohmeier
- Austrian Centre of Industrial Biotechnology, Petersgasse 14, A-8010 Graz, Austria
| | - Harald Pichler
- Austrian Centre of Industrial Biotechnology, Petersgasse 14, A-8010 Graz, Austria
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, A-8010 Graz, Austria
| | - Oliver May
- DSM—Innovative Synthesis BV, Geleen, P.O. Box 18, 6160 MD Geleen, The Netherlands
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62
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Ferdjani S, Ionita M, Roy B, Dion M, Djeghaba Z, Rabiller C, Tellier C. Correlation between thermostability and stability of glycosidases in ionic liquid. Biotechnol Lett 2011; 33:1215-9. [PMID: 21331585 DOI: 10.1007/s10529-011-0560-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 01/31/2011] [Indexed: 11/29/2022]
Abstract
The activity and stability of a β-glycosidase (Thermus thermophilus) and two α-galactosidases (Thermotoga maritima and Bacillus stearothermophilus) were studied in different hydrophilic ionic liquid (IL)/water ratios. For the ILs used, the glycosidases showed the best stability and activity in 1,3-dimethylimidazolium methyl sulfate [MMIM][MeSO(4)] and 1,2,3-trimethylimidazolium methyl sulfate [TMIM][MeSO(4)]. A close correlation was observed between the thermostability of the enzymes and their stability in IL media. At high IL concentration (80%), a time-dependent irreversible denaturing effect was observed on glycosidases while, at lower concentration (<30%), a reversible inactivation affecting mainly the k (cat) was obtained. The results demonstrate that highly thermostable glycosidases are more suitable for biocatalytic reactions in water-miscible ILs.
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Affiliation(s)
- Salim Ferdjani
- Biotechnologie, Biocatalyse et Biorégulation, UMR 6204 CNRS, Université de Nantes, 2, rue de la Houssinière, 44322, Nantes cedex 03, France
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63
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64
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Hartl L, Gastebois A, Aimanianda V, Latgé JP. Characterization of the GPI-anchored endo β-1,3-glucanase Eng2 of Aspergillus fumigatus. Fungal Genet Biol 2010; 48:185-91. [PMID: 20619350 PMCID: PMC3092853 DOI: 10.1016/j.fgb.2010.06.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 06/18/2010] [Accepted: 06/18/2010] [Indexed: 11/15/2022]
Abstract
A GPI-anchored endo β-1,3-glucanase of Aspergillus fumigatus was characterized. The enzyme encoded by ENG2 (AFUA_2g14360) belongs to the glycoside hydrolase family 16 (GH16). The activity was characterized using a recombinant protein produced by Pichiapastoris. The recombinant enzyme preferentially acts on soluble β-1,3-glucans. Enzymatic analysis of the endoglucanase activity using Carboxymethyl-Curdlan-Remazol Brilliant Blue (CM-Curdlan-RBB) as a substrate revealed a wide temperature optimum of 24-40°C, a pH optimum of 5.0-6.5 and a K(m) of 0.8 mg ml(-1). HPAEC analysis of the products formed by Eng2 when acting on different oligo-β-1,3-glucans confirmed the predicted endoglucanase activity and also revealed a transferase activity for oligosaccharides of a low degree of polymerization. The growth phenotype of the Afeng2 mutant was identical to that of the wt strain.
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Affiliation(s)
- Lukas Hartl
- Unité des Aspergillus, Département de Parasitologie et Mycologie, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris cedex 15, France
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65
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Tran V, Hoffmann L, Rabiller C, Tellier C, Dion M. Rational design of a GH1 beta-glycosidase to prevent self-condensation during the transglycosylation reaction. Protein Eng Des Sel 2010; 23:43-9. [PMID: 19926593 DOI: 10.1093/protein/gzp068] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Mutant N282T of a thermostable beta-glycosidase from GH1 family (TtbetaGly) presenting a high transglycosidase activity was previously obtained by directed evolution. However, it displays a self-condensation activity with the donor 2-nitrophenyl-beta-d-galactopyranoside (oNPGal) which competes with the condensation reaction and entails undesirable effects. In order to prevent this reaction, we rationally modified this enzyme at the [+1]/[+2] subsites so that oNPGal would bind less tightly. Molecular modeling (MM) suggested the mutation A221W, which decreased the affinity of the donor at these sites and moved it away from the bound galactose at the -1 subsite. A single (A221W) and a double mutant (A221W/N282T) were constructed, and they gave rise to a drastic decrease in self-condensation. The A221W mutant had no transglycosylation activity whereas the A221W/N282T mutant still displayed a condensation activity, comparable to that of the N282T mutant for the transfer on pNPGlcNAc. MM revealed that the double mutant A221W/N282T could induce the synthesis of a glycosidic bond between a donor and an acceptor displaying an equatorial 4-position. Moreover, it is suggested that mutation N282T could change the orientation of residue N219, leading to a stabilization of the acceptor with a new hydrogen bond. This finding opens the way to further improvements of evolved transglycosidases.
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Affiliation(s)
- Vinh Tran
- Faculté des Sciences et des Techniques, Biotechnologie, Biocatalyse, Biorégulation (UMR CNRS 6204) Nantes University, PRES UNAM, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3, France
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66
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Evolved beta-galactosidases from Geobacillus stearothermophilus with improved transgalactosylation yield for galacto-oligosaccharide production. Appl Environ Microbiol 2009; 75:6312-21. [PMID: 19666723 DOI: 10.1128/aem.00714-09] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A mutagenesis approach was applied to the beta-galactosidase BgaB from Geobacillus stearothermophilus KVE39 in order to improve its enzymatic transglycosylation of lactose into oligosaccharides. A simple screening strategy, which was based on the reduction of the hydrolysis of a potential transglycosylation product (lactosucrose), provided mutant enzymes possessing improved synthetic properties for the autocondensation product from nitrophenyl-galactoside and galacto-oligosaccharides (GOS) from lactose. The effects of the mutations on enzyme activity and kinetics were determined. An change of one arginine to lysine (R109K) increased the oligosaccharide yield compared to that for the wild-type BgaB. Subsequently, saturation mutagenesis at this position demonstrated that valine and tryptophan further increased the transglycosylation performance of BgaB. During the transglycosylation reaction with lactose of the evolved beta-galactosidases, a major trisaccharide was formed. Its structure was characterized as beta-D-galactopyranosyl-(1-->3)-beta-D-galactopyranosyl-(1-->4)-D-glucopyranoside (3'-galactosyl-lactose). At the lactose concentration of 18% (wt/vol), this trisaccharide was obtained in yields of 11.5% (wt/wt) with GP21 (BgaB R109K), 21% with GP637.2 (BgaB R109V), and only 2% with the wild-type BgaB enzyme. GP643.3 (BgaB R109W) was shown to be the most efficient mutant, with a 3'-galactosyl-lactose production of 23%.
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67
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D’Almeida A, Ionata M, Tran V, Tellier C, Dion M, Rabiller C. An expeditious and efficient synthesis of β-d-galactopyranosyl-(1→3)-d-N-acetylglucosamine (lacto-N-biose) using a glycosynthase from Thermus thermophilus as a catalyst. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.tetasy.2009.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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68
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Bojarová P, Kren V. Glycosidases: a key to tailored carbohydrates. Trends Biotechnol 2009; 27:199-209. [PMID: 19250692 DOI: 10.1016/j.tibtech.2008.12.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 12/03/2008] [Accepted: 12/12/2008] [Indexed: 10/21/2022]
Abstract
In recent years, carbohydrate-processing enzymes have become the enzymes of choice in many applications thanks to their stereoselectivity and efficiency. This review presents recent developments in glycosidase-catalyzed synthesis via two complementary approaches: the use of wild-type enzymes with engineered substrates, and mutant glycosidases. Genetic engineering has recently produced glucuronyl synthases, an inverting xylosynthase and the first mutant endo-beta-N-acetylglucosaminidase. A thorough selection of enzyme strains and aptly modified substrates have resulted in rare glycostructures, such as N-acetyl-beta-galactosaminuronates, beta1,4-linked mannosides and alpha1,4-linked galactosides. The efficient selection of mutant enzymes is facilitated by high-throughput screening assays involving the co-expression of coupled enzymes or chemical complementation. Selective glycosidase inhibitors and highly specific glycosidases are finding attractive applications in biomedicine, biology and proteomics.
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Affiliation(s)
- Pavla Bojarová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Center of Biocatalysis and Biotransformation, Vídenská 1083, CZ-142 20, Praha 4, Czech Republic
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69
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Evaluation of GFP Tag as a Screening Reporter in Directed Evolution of a Hyperthermophilic β-Glucosidase. Mol Biotechnol 2009; 42:205-15. [DOI: 10.1007/s12033-009-9152-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 01/26/2009] [Indexed: 10/21/2022]
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Koné FMT, Le Béchec M, Sine JP, Dion M, Tellier C. Digital screening methodology for the directed evolution of transglycosidases. Protein Eng Des Sel 2008; 22:37-44. [PMID: 18996967 DOI: 10.1093/protein/gzn065] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Engineering of glycosidases with efficient transglycosidases activity is an alternative to glycosyltransferases or glycosynthases for the synthesis of oligosaccharides and glycoconjugates. However, the engineering of transglycosidases by directed evolution methodologies is hampered by the lack of efficient screening systems for sugar-transfer activity. We report here the development of digital imaging-based high-throughput screening methodology for the directed evolution of glycosidases into transgalactosidases. Using this methodology, we detected transglycosidase mutants in intact Escherichia coli cells by digital imaging monitoring of the activation of non- or low-hydrolytic mutants by an acceptor substrate. We screened several libraries of mutants of beta-glycosidase from Thermus thermophilus using this methodology and found variants with up to a 70-fold overall increase in the transglycosidase/hydrolysis activity ratio. Using natural disaccharide acceptors, these transglycosidase mutants were able to synthesise trisaccharides, as a mixture of two regioisomers, with up to 76% yield.
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Affiliation(s)
- Fankroma M T Koné
- Biotechnologie, Biocatalyse, Biorégulation, Faculté des Sciences et des Techniques, Université de Nantes, UMR CNRS 6204, 2, rue de la Houssinière, BP 92208, Nantes, F-44322 France
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71
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Engineering of glucoside acceptors for the regioselective synthesis of β-(1→3)-disaccharides with glycosynthases. Carbohydr Res 2008; 343:2939-46. [DOI: 10.1016/j.carres.2008.07.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 07/13/2008] [Accepted: 07/15/2008] [Indexed: 11/15/2022]
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72
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Elimination of competing hydrolysis and coupling side reactions of a cyclodextrin glucanotransferase by directed evolution. Biochem J 2008; 413:517-25. [PMID: 18422488 DOI: 10.1042/bj20080353] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Thermoanaerobacterium thermosulfurigenes cyclodextrin glucanotransferase primarily catalyses the formation of cyclic alpha-(1,4)-linked oligosaccharides (cyclodextrins) from starch. This enzyme also possesses unusually high hydrolytic activity as a side reaction, thought to be due to partial retention of ancestral enzyme function. This side reaction is undesirable, since it produces short saccharides that are responsible for the breakdown of the cyclodextrins formed, thus limiting the yield of cyclodextrins produced. To reduce the competing hydrolysis reaction, while maintaining the cyclization activity, we applied directed evolution, introducing random mutations throughout the cgt gene by error-prone PCR. Mutations in two residues, Ser-77 and Trp-239, on the outer region of the active site, lowered the hydrolytic activity up to 15-fold with retention of cyclization activity. In contrast, mutations within the active site could not lower hydrolytic rates, indicating an evolutionary optimized role for cyclodextrin formation by residues within this region. The crystal structure of the most effective mutant, S77P, showed no alterations to the peptide backbone. However, subtle conformational changes to the side chains of active-site residues had occurred, which may explain the increased cyclization/hydrolysis ratio. This indicates that secondary effects of mutations located on the outer regions of the catalytic site are required to lower the rates of competing side reactions, while maintaining the primary catalytic function. Subsequent functional analysis of various glucanotransferases from the superfamily of glycoside hydrolases also suggests a gradual evolutionary progression of these enzymes from a common 'intermediate-like' ancestor towards specific transglycosylation activity.
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A universal screening assay for glycosynthases: directed evolution of glycosynthase XynB2(E335G) suggests a general path to enhance activity. ACTA ACUST UNITED AC 2008; 15:546-51. [PMID: 18559265 DOI: 10.1016/j.chembiol.2008.05.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 04/30/2008] [Accepted: 05/02/2008] [Indexed: 11/20/2022]
Abstract
Glycosynthases are catalytic mutants of mainly retaining glycoside hydrolases that catalyze the synthesis of oligosaccharides from their corresponding glycosyl-fluoride donors and suitable acceptors. Here we describe the development of a general, high-throughput screening procedure for glycosynthase activity, which is based on the release of hydrofluoric acid, a by-product of all glycosynthase reactions. This assay is sensitive, does not require the synthesis of special chromophoric or modified substrates, and, most importantly, is applicable for all glycosynthases. We used this screening procedure on error-prone PCR libraries to isolate improved glycosynthase variants of XynB2(E335G) glycosynthase, a family 52 beta-xylosidase from Geobacillus stearothermophilus. The improved variants exhibited higher K(M) values toward the acceptor and the donor, suggesting that enzyme-product release is rate determining for k(cat).
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74
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Yang SJ, Min BC, Kim YW, Jang SM, Lee BH, Park KH. Changes in the catalytic properties of Pyrococcus furiosus thermostable amylase by mutagenesis of the substrate binding sites. Appl Environ Microbiol 2007; 73:5607-12. [PMID: 17630303 PMCID: PMC2042082 DOI: 10.1128/aem.00499-07] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pyrococcus furiosus thermostable amylase (TA) is a cyclodextrin (CD)-degrading enzyme with a high preference for CDs over maltooligosaccharides. In this study, we investigated the roles of four residues (His414, Gly415, Met439, and Asp440) in the function of P. furiosus TA by using site-directed mutagenesis and kinetic analysis. A variant form of P. furiosus TA containing two mutations (H414N and G415E) exhibited strongly enhanced alpha-(1,4)-transglycosylation activity, resulting in the production of a series of maltooligosaccharides that were longer than the initial substrates. In contrast, the variant enzymes with single mutations (H414N or G415E) showed a substrate preference similar to that of the wild-type enzyme. Other mutations (M439W and D440H) reversed the substrate preference of P. furiosus TA from CDs to maltooligosaccharides. Relative substrate preferences for maltoheptaose over beta-CD, calculated by comparing k(cat)/K(m) ratios, of 1, 8, and 26 for wild-type P. furiosus TA, P. furiosus TA with D440H, and P. furiosus TA with M439W and D440H, respectively, were found. Our results suggest that His414, Gly415, Met439, and Asp440 play important roles in substrate recognition and transglycosylation. Therefore, this study provides information useful in engineering glycoside hydrolase family 13 enzymes.
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Affiliation(s)
- Sung-Jae Yang
- Center for Agricultural Biomaterials and Department of Food Science and Biotechnology, Seoul National University, Sillim-dong, Kwanak-gu, Seoul 151-921, Korea
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75
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Splechtna B, Nguyen TH, Zehetner R, Lettner HP, Lorenz W, Haltrich D. Process development for the production of prebiotic galacto-oligosaccharides from lactose using β-galactosidase fromLactobacillus sp. Biotechnol J 2007; 2:480-5. [PMID: 17285679 DOI: 10.1002/biot.200600230] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Galacto-oligosaccharides (GOS) are formed from lactose in discontinuous mode of conversion using beta-galactosidase from Lactobacillus sp. (beta-gal). The discontinuous process was optimized for technical application with regard to GOS yield, enzyme preparation, reaction temperature and substrate source. It proved to be advantageous to directly apply the crude cell-free enzyme extract for the conversion, since similar GOS yields and composition were obtained as when using the pure enzyme preparation, but expensive purification could be avoided. Reaction temperature was lowered to 17 degrees C to limit microbial contamination when using technical substrates. Thereby GOS yield decreased from 30% to 28% of total sugars and enzyme demand increased 2.7-fold. Whey permeate was compared to buffered lactose solution as a substrate source. The initial reaction rate was found to be 1.8 times higher for the whey permeate substrate; however, GOS yield was slightly lower (approximately 25% of total sugar at 17 degrees C) mainly due to smaller amounts of allolactose[beta-D-Galp-(1-->6)-D-Glc] and the trisaccharide beta-D-Galp-(1-->6)-D-Lac formed.
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Onaca C, Kieninger M, Engesser KH, Altenbuchner J. Degradation of alkyl methyl ketones by Pseudomonas veronii MEK700. J Bacteriol 2007; 189:3759-67. [PMID: 17351032 PMCID: PMC1913341 DOI: 10.1128/jb.01279-06] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas veronii MEK700 was isolated from a biotrickling filter cleaning 2-butanone-loaded waste air. The strain is able to grow on 2-butanone and 2-hexanol. The genes for degradation of short chain alkyl methyl ketones were identified by transposon mutagenesis using a newly designed transposon, mini-Tn5495, and cloned in Escherichia coli. DNA sequence analysis of a 15-kb fragment revealed three genes involved in methyl ketone degradation. The deduced amino acid sequence of the first gene, mekA, had high similarity to Baeyer-Villiger monooxygenases; the protein of the second gene, mekB, had similarity to homoserine acetyltransferases; the third gene, mekR, encoded a putative transcriptional activator of the AraC/XylS family. The three genes were located between two gene groups: one comprising a putative phosphoenolpyruvate synthase and glycogen synthase, and the other eight genes for the subunits of an ATPase. Inactivation of mekA and mekB by insertion of the mini-transposon abolished growth of P. veronii MEK700 on 2-butanone and 2-hexanol. The involvement of mekR in methyl ketone degradation was observed by heterologous expression of mekA and mekB in Pseudomonas putida. A fragment containing mekA and mekB on a plasmid was not sufficient to allow P. putida KT2440 to grow on 2-butanone. Not until all three genes were assembled in the recombinant P. putida was it able to use 2-butanone as carbon source. The Baeyer-Villiger monooxygenase activity of MekA was clearly demonstrated by incubating a mekB transposon insertion mutant of P. veronii with 2-butanone. Hereby, ethyl acetate was accumulated. To our knowledge, this is the first time that ethyl acetate by gas chromatographic analysis has been definitely demonstrated to be an intermediate of MEK degradation. The mekB-encoded protein was heterologously expressed in E. coli and purified by immobilized metal affinity chromatography. The protein exhibited high esterase activity towards short chain esters like ethyl acetate and 4-nitrophenyl acetate.
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Affiliation(s)
- Christina Onaca
- Institut für Industrielle Genetik, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
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Johannes TW, Zhao H. Directed evolution of enzymes and biosynthetic pathways. Curr Opin Microbiol 2006; 9:261-7. [PMID: 16621678 DOI: 10.1016/j.mib.2006.03.003] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Accepted: 03/31/2006] [Indexed: 11/19/2022]
Abstract
Directed evolution is an important tool for overcoming the limitations of natural enzymes as biocatalysts. Recent advances have focused on applying directed evolution to a variety of enzymes, such as epoxide hydrolase, glyphosate N-acetyltransferase, xylanase and phosphotriesterase, in order to improve their activity, selectivity, stability and solubility. The focus has also shifted to manipulating biosynthetic pathways for the production of many naturally synthesized compounds, as well as the production of novel 'unnatural' compounds. A combined directed evolution and computational design approach is becoming increasingly important in exploring enzyme sequence-space and creating improved or novel enzymes. Fueled by recent breakthroughs in genomics and metagenomics, these developments should help expand the use of biocatalysts in industry.
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Affiliation(s)
- Tyler W Johannes
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S Mathews Avenue, Urbana, IL 61801, USA
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