1
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Rzechorzek NJ, Kunzelmann S, Purkiss AG, Silva Dos Santos M, MacRae JI, Taylor IA, Fugger K, West SC. Mechanism of substrate hydrolysis by the human nucleotide pool sanitiser DNPH1. Nat Commun 2023; 14:6809. [PMID: 37884503 PMCID: PMC10603095 DOI: 10.1038/s41467-023-42544-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 10/13/2023] [Indexed: 10/28/2023] Open
Abstract
Poly(ADP-ribose) polymerase (PARP) inhibitors are used in the clinic to treat BRCA-deficient breast, ovarian and prostate cancers. As their efficacy is potentiated by loss of the nucleotide salvage factor DNPH1 there is considerable interest in the development of highly specific small molecule DNPH1 inhibitors. Here, we present X-ray crystal structures of dimeric DNPH1 bound to its substrate hydroxymethyl deoxyuridine monophosphate (hmdUMP). Direct interaction with the hydroxymethyl group is important for substrate positioning, while conserved residues surrounding the base facilitate target discrimination. Glycosidic bond cleavage is driven by a conserved catalytic triad and proceeds via a two-step mechanism involving formation and subsequent disruption of a covalent glycosyl-enzyme intermediate. Mutation of a previously uncharacterised yet conserved glutamate traps the intermediate in the active site, demonstrating its role in the hydrolytic step. These observations define the enzyme's catalytic site and mechanism of hydrolysis, and provide important insights for inhibitor discovery.
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Affiliation(s)
- Neil J Rzechorzek
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Simone Kunzelmann
- Structural Biology Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Andrew G Purkiss
- Structural Biology Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Mariana Silva Dos Santos
- Metabolomics Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - James I MacRae
- Metabolomics Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Kasper Fugger
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
- University College London Cancer Institute, 72 Huntley Street, London, WC1E 6DD, UK
| | - Stephen C West
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
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2
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Collet L, Vander Wauven C, Oudjama Y, Galleni M, Dutoit R. Glycoside hydrolase family 5: structural snapshots highlighting the involvement of two conserved residues in catalysis. Acta Crystallogr D Struct Biol 2021; 77:205-216. [PMID: 33559609 DOI: 10.1107/s2059798320015557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/24/2020] [Indexed: 11/10/2022] Open
Abstract
The ability of retaining glycoside hydrolases (GHs) to transglycosylate is inherent to the double-displacement mechanism. Studying reaction intermediates, such as the glycosyl-enzyme intermediate (GEI) and the Michaelis complex, could provide valuable information to better understand the molecular factors governing the catalytic mechanism. Here, the GEI structure of RBcel1, an endo-1,4-β-glucanase of the GH5 family endowed with transglycosylase activity, is reported. It is the first structure of a GH5 enzyme covalently bound to a natural oligosaccharide with the two catalytic glutamate residues present. The structure of the variant RBcel1_E135A in complex with cellotriose is also reported, allowing a description of the entire binding cleft of RBcel1. Taken together, the structures deliver different snapshots of the double-displacement mechanism. The structural analysis revealed a significant movement of the nucleophilic glutamate residue during the reaction. Enzymatic assays indicated that, as expected, the acid/base glutamate residue is crucial for the glycosylation step and partly contributes to deglycosylation. Moreover, a conserved tyrosine residue in the -1 subsite, Tyr201, plays a determinant role in both the glycosylation and deglycosylation steps, since the GEI was trapped in the RBcel1_Y201F variant. The approach used to obtain the GEI presented here could easily be transposed to other retaining GHs in clan GH-A.
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Affiliation(s)
| | | | | | - Moreno Galleni
- Center for Protein Engineering (CIP), Biological Macromolecules, University of Liège, 13 Allée du 6 Août, 4000 Liège, Belgium
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3
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Structure and mechanism of the ER-based glucosyltransferase ALG6. Nature 2020; 579:443-447. [PMID: 32103179 DOI: 10.1038/s41586-020-2044-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 01/06/2020] [Indexed: 01/03/2023]
Abstract
In eukaryotic protein N-glycosylation, a series of glycosyltransferases catalyse the biosynthesis of a dolichylpyrophosphate-linked oligosaccharide before its transfer onto acceptor proteins1. The final seven steps occur in the lumen of the endoplasmic reticulum (ER) and require dolichylphosphate-activated mannose and glucose as donor substrates2. The responsible enzymes-ALG3, ALG9, ALG12, ALG6, ALG8 and ALG10-are glycosyltransferases of the C-superfamily (GT-Cs), which are loosely defined as containing membrane-spanning helices and processing an isoprenoid-linked carbohydrate donor substrate3,4. Here we present the cryo-electron microscopy structure of yeast ALG6 at 3.0 Å resolution, which reveals a previously undescribed transmembrane protein fold. Comparison with reported GT-C structures suggests that GT-C enzymes contain a modular architecture with a conserved module and a variable module, each with distinct functional roles. We used synthetic analogues of dolichylphosphate-linked and dolichylpyrophosphate-linked sugars and enzymatic glycan extension to generate donor and acceptor substrates using purified enzymes of the ALG pathway to recapitulate the activity of ALG6 in vitro. A second cryo-electron microscopy structure of ALG6 bound to an analogue of dolichylphosphate-glucose at 3.9 Å resolution revealed the active site of the enzyme. Functional analysis of ALG6 variants identified a catalytic aspartate residue that probably acts as a general base. This residue is conserved in the GT-C superfamily. Our results define the architecture of ER-luminal GT-C enzymes and provide a structural basis for understanding their catalytic mechanisms.
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4
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Mazurkewich S, Poulsen JCN, Lo Leggio L, Larsbrink J. Structural and biochemical studies of the glucuronoyl esterase OtCE15A illuminate its interaction with lignocellulosic components. J Biol Chem 2019; 294:19978-19987. [PMID: 31740581 PMCID: PMC6937553 DOI: 10.1074/jbc.ra119.011435] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/11/2019] [Indexed: 12/28/2022] Open
Abstract
Glucuronoyl esterases (GEs) catalyze the cleavage of ester linkages between lignin and glucuronic acid moieties on glucuronoxylan in plant biomass. As such, GEs represent promising biochemical tools in industrial processing of these recalcitrant resources. However, details on how GEs interact and catalyze degradation of their natural substrates are sparse, calling for thorough enzyme structure-function studies. Presented here is a structural and mechanistic investigation of the bacterial GE OtCE15A. GEs belong to the carbohydrate esterase family 15 (CE15), which is in turn part of the larger α/β-hydrolase superfamily. GEs contain a Ser-His-Asp/Glu catalytic triad, but the location of the catalytic acid in GEs has been shown to be variable, and OtCE15A possesses two putative catalytic acidic residues in the active site. Through site-directed mutagenesis, we demonstrate that these residues are functionally redundant, possibly indicating the evolutionary route toward new functionalities within the family. Structures determined with glucuronate, in both native and covalently bound intermediate states, and galacturonate provide insights into the catalytic mechanism of CE15. A structure of OtCE15A with the glucuronoxylooligosaccharide 23-(4-O-methyl-α-d-glucuronyl)-xylotriose (commonly referred to as XUX) shows that the enzyme can indeed interact with polysaccharides from the plant cell wall, and an additional structure with the disaccharide xylobiose revealed a surface binding site that could possibly indicate a recognition mechanism for long glucuronoxylan chains. Collectively, the results indicate that OtCE15A, and likely most of the CE15 family, can utilize esters of glucuronoxylooligosaccharides and support the proposal that these enzymes work on lignin-carbohydrate complexes in plant biomass.
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Affiliation(s)
- Scott Mazurkewich
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | | | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Johan Larsbrink
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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5
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Geronimo I, Payne CM, Sandgren M. Hydrolysis and Transglycosylation Transition States of Glycoside Hydrolase Family 3 β-Glucosidases Differ in Charge and Puckering Conformation. J Phys Chem B 2018; 122:9452-9459. [DOI: 10.1021/acs.jpcb.8b07118] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Inacrist Geronimo
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Box 7015, 750 07 Uppsala, Sweden
| | - Christina M. Payne
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky 40506-0046, United States
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Box 7015, 750 07 Uppsala, Sweden
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6
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Yang J, Han Z. Understanding the Positional Binding and Substrate Interaction of a Highly Thermostable GH10 Xylanase from Thermotoga maritima by Molecular Docking. Biomolecules 2018; 8:biom8030064. [PMID: 30061529 PMCID: PMC6163442 DOI: 10.3390/biom8030064] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/24/2018] [Accepted: 07/26/2018] [Indexed: 11/16/2022] Open
Abstract
Glycoside hydrolase family 10 (GH10) xylanases are responsible for enzymatic cleavage of the internal glycosidic linkages of the xylan backbone, to generate xylooligosaccharides (XOS) and xyloses. The topologies of active-site cleft determine the substrate preferences and product profiles of xylanases. In this study, positional bindings and substrate interactions of TmxB, one of the most thermostable xylanases characterized from Thermotoga maritima to date, was investigated by docking simulations. XOS with backbone lengths of two to five (X2–X5) were docked into the active-site cleft of TmxB by AutoDock The modeled complex structures provided a series of snapshots of the interactions between XOS and TmxB. Changes in binding energy with the length of the XOS backbone indicated the existence of four effective subsites in TmxB. The interaction patterns at subsites −2 to +1 in TmxB were conserved among GH10 xylanases whereas those at distal aglycone subsite +2, consisting of the hydrogen bond network, was unique for TmxB. This work helps in obtaining an in-depth understanding of the substrate-binding property of TmxB and provides a basis for rational design of mutants with desired product profiles.
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Affiliation(s)
- Jiangke Yang
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China.
| | - Zhenggang Han
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China.
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7
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Improvement of the catalytic characteristics of a salt-tolerant GH10 xylanase from Streptomyce rochei L10904. Int J Biol Macromol 2018; 107:1447-1455. [DOI: 10.1016/j.ijbiomac.2017.10.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 09/30/2017] [Accepted: 10/03/2017] [Indexed: 11/18/2022]
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8
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A novel pH-stable, endoglucanase (JqCel5A) isolated from a salt-lake microorganism, Jonesia quinghaiensis. ELECTRON J BIOTECHN 2016. [DOI: 10.1016/j.ejbt.2016.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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9
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Raich L, Borodkin V, Fang W, Castro-López J, van Aalten DMF, Hurtado-Guerrero R, Rovira C. A Trapped Covalent Intermediate of a Glycoside Hydrolase on the Pathway to Transglycosylation. Insights from Experiments and Quantum Mechanics/Molecular Mechanics Simulations. J Am Chem Soc 2016; 138:3325-32. [DOI: 10.1021/jacs.5b10092] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Lluís Raich
- Departament
de Química Inorgànica i Orgànica and Institut
de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
| | | | | | - Jorge Castro-López
- Institute
of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC) Joint Unit, Mariano Esquillor s/n, Campus Rio
Ebro, Edificio I+D, 50018 Zaragoza, Spain
| | | | - Ramón Hurtado-Guerrero
- Fundación ARAID, Edificio CEEI
Aragón, 50018 Zaragoza, Spain
- Institute
of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC) Joint Unit, Mariano Esquillor s/n, Campus Rio
Ebro, Edificio I+D, 50018 Zaragoza, Spain
| | - Carme Rovira
- Departament
de Química Inorgànica i Orgànica and Institut
de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys, 23, 08020 Barcelona, Spain
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10
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Direct determination of protonation states and visualization of hydrogen bonding in a glycoside hydrolase with neutron crystallography. Proc Natl Acad Sci U S A 2015; 112:12384-9. [PMID: 26392527 DOI: 10.1073/pnas.1504986112] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glycoside hydrolase (GH) enzymes apply acid/base chemistry to catalyze the decomposition of complex carbohydrates. These ubiquitous enzymes accept protons from solvent and donate them to substrates at close to neutral pH by modulating the pKa values of key side chains during catalysis. However, it is not known how the catalytic acid residue acquires a proton and transfers it efficiently to the substrate. To better understand GH chemistry, we used macromolecular neutron crystallography to directly determine protonation and ionization states of the active site residues of a family 11 GH at multiple pD (pD=pH+0.4) values. The general acid glutamate (Glu) cycles between two conformations, upward and downward, but is protonated only in the downward orientation. We performed continuum electrostatics calculations to estimate the pKa values of the catalytic Glu residues in both the apo- and substrate-bound states of the enzyme. The calculated pKa of the Glu increases substantially when the side chain moves down. The energy barrier required to rotate the catalytic Glu residue back to the upward conformation, where it can protonate the glycosidic oxygen of the substrate, is 4.3 kcal/mol according to free energy simulations. These findings shed light on the initial stage of the glycoside hydrolysis reaction in which molecular motion enables the general acid catalyst to obtain a proton from the bulk solvent and deliver it to the glycosidic oxygen.
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11
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Kallemeijn WW, Witte MD, Wennekes T, Aerts JMFG. Mechanism-based inhibitors of glycosidases: design and applications. Adv Carbohydr Chem Biochem 2015; 71:297-338. [PMID: 25480507 DOI: 10.1016/b978-0-12-800128-8.00004-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article covers recent developments in the design and application of activity-based probes (ABPs) for glycosidases, with emphasis on the different enzymes involved in metabolism of glucosylceramide in humans. Described are the various catalytic reaction mechanisms employed by inverting and retaining glycosidases. An understanding of catalysis at the molecular level has stimulated the design of different types of ABPs for glycosidases. Such compounds range from (1) transition-state mimics tagged with reactive moieties, which associate with the target active site—forming covalent bonds in a relatively nonspecific manner in or near the catalytic pocket—to (2) enzyme substrates that exploit the catalytic mechanism of retaining glycosidase targets to release a highly reactive species within the active site of the enzyme, to (3) probes based on mechanism-based, covalent, and irreversible glycosidase inhibitors. Some applications in biochemical and biological research of the activity-based glycosidase probes are discussed, including specific quantitative visualization of active enzyme molecules in vitro and in vivo, and as strategies for unambiguously identifying catalytic residues in glycosidases in vitro.
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Affiliation(s)
- Wouter W Kallemeijn
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Martin D Witte
- Department of Bio-Organic Chemistry, Stratingh Institute for Chemistry, University of Groningen, Groningen, The Netherlands.
| | - Tom Wennekes
- Department of Synthetic Organic Chemistry, Wageningen University, Wageningen, The Netherlands.
| | - Johannes M F G Aerts
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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12
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Bissaro B, Durand J, Biarnés X, Planas A, Monsan P, O’Donohue MJ, Fauré R. Molecular Design of Non-Leloir Furanose-Transferring Enzymes from an α-l-Arabinofuranosidase: A Rationale for the Engineering of Evolved Transglycosylases. ACS Catal 2015. [DOI: 10.1021/acscatal.5b00949] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bastien Bissaro
- Université
de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France
- INRA, UMR792,
Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France
- CNRS, UMR5504, F-31400 Toulouse, France
| | - Julien Durand
- Université
de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France
- INRA, UMR792,
Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France
- CNRS, UMR5504, F-31400 Toulouse, France
| | - Xevi Biarnés
- Laboratory
of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta, 08017 Barcelona, Spain
| | - Antoni Planas
- Laboratory
of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta, 08017 Barcelona, Spain
| | - Pierre Monsan
- Université
de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France
- INRA, UMR792,
Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France
- CNRS, UMR5504, F-31400 Toulouse, France
- Toulouse White
Biotechnology, UMS INRA/INSA 1337, UMS CNRS/INSA 3582, 3 Rue des Satellites, 31400 Toulouse, France
| | - Michael J. O’Donohue
- Université
de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France
- INRA, UMR792,
Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France
- CNRS, UMR5504, F-31400 Toulouse, France
| | - Régis Fauré
- Université
de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France
- INRA, UMR792,
Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France
- CNRS, UMR5504, F-31400 Toulouse, France
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13
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Glycosynthesis in a waterworld: new insight into the molecular basis of transglycosylation in retaining glycoside hydrolases. Biochem J 2015; 467:17-35. [PMID: 25793417 DOI: 10.1042/bj20141412] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Carbohydrates are ubiquitous in Nature and play vital roles in many biological systems. Therefore the synthesis of carbohydrate-based compounds is of considerable interest for both research and commercial purposes. However, carbohydrates are challenging, due to the large number of sugar subunits and the multiple ways in which these can be linked together. Therefore, to tackle the challenge of glycosynthesis, chemists are increasingly turning their attention towards enzymes, which are exquisitely adapted to the intricacy of these biomolecules. In Nature, glycosidic linkages are mainly synthesized by Leloir glycosyltransferases, but can result from the action of non-Leloir transglycosylases or phosphorylases. Advantageously for chemists, non-Leloir transglycosylases are glycoside hydrolases, enzymes that are readily available and exhibit a wide range of substrate specificities. Nevertheless, non-Leloir transglycosylases are unusual glycoside hydrolases in as much that they efficiently catalyse the formation of glycosidic bonds, whereas most glycoside hydrolases favour the mechanistically related hydrolysis reaction. Unfortunately, because non-Leloir transglycosylases are almost indistinguishable from their hydrolytic counterparts, it is unclear how these enzymes overcome the ubiquity of water, thus avoiding the hydrolytic reaction. Without this knowledge, it is impossible to rationally design non-Leloir transglycosylases using the vast diversity of glycoside hydrolases as protein templates. In this critical review, a careful analysis of literature data describing non-Leloir transglycosylases and their relationship to glycoside hydrolase counterparts is used to clarify the state of the art knowledge and to establish a new rational basis for the engineering of glycoside hydrolases.
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14
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Zhang Y, Zhao Z, Liu H. Deriving Chemically Essential Interactions Based on Active Site Alignments and Quantum Chemical Calculations: A Case Study on Glycoside Hydrolases. ACS Catal 2015. [DOI: 10.1021/cs501709d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yinliang Zhang
- School
of Life Sciences, University of Science and Technology of China, 443 Huangshan Road, Hefei, Anhui 230027, China
| | - Zheng Zhao
- Hefei
Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Haiyan Liu
- School
of Life Sciences, University of Science and Technology of China, 443 Huangshan Road, Hefei, Anhui 230027, China
- Hefei National Laboratory for Physical Sciences at the Microscales, Hefei, Anhui 230027, China
- Hefei
Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
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15
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Molecular modeling and MM-PBSA free energy analysis of endo-1,4-β-xylanase from Ruminococcus albus 8. Int J Mol Sci 2014; 15:17284-303. [PMID: 25264743 PMCID: PMC4227162 DOI: 10.3390/ijms151017284] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 09/11/2014] [Accepted: 09/15/2014] [Indexed: 11/16/2022] Open
Abstract
Endo-1,4-β-xylanase (EC 3.2.1.8) is the enzyme from Ruminococcus albus 8 (R. albus 8) (Xyn10A), and catalyzes the degradation of arabinoxylan, which is a major cell wall non-starch polysaccharide of cereals. The crystallographic structure of Xyn10A is still unknown. For this reason, we report a computer-assisted homology study conducted to build its three-dimensional structure based on the known sequence of amino acids of this enzyme. In this study, the best similarity was found with the Clostridium thermocellum (C. thermocellum) N-terminal endo-1,4-β-D-xylanase 10 b. Following the 100 ns molecular dynamics (MD) simulation, a reliable model was obtained for further studies. Molecular Mechanics/Poisson-Boltzmann Surface Area (MM-PBSA) methods were used for the substrate xylotetraose having the reactive sugar, which was bound in the -1 subsite of Xyn10A in the 4C1 (chair) and 2SO (skew boat) ground state conformations. According to the simulations and free energy analysis, Xyn10A binds the substrate with the -1 sugar in the 2SO conformation 39.27 kcal·mol(-1) tighter than the substrate with the sugar in the 4C1 conformation. According to the Xyn10A-2SO Xylotetraose (X4(sb) interaction energies, the most important subsite for the substrate binding is subsite -1. The results of this study indicate that the substrate is bound in a skew boat conformation with Xyn10A and the -1 sugar subsite proceeds from the 4C1 conformation through 2SO to the transition state. MM-PBSA free energy analysis indicates that Asn187 and Trp344 in subsite -1 may an important residue for substrate binding. Our findings provide fundamental knowledge that may contribute to further enhancement of enzyme performance through molecular engineering.
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16
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A C-terminal proline-rich sequence simultaneously broadens the optimal temperature and pH ranges and improves the catalytic efficiency of glycosyl hydrolase family 10 ruminal xylanases. Appl Environ Microbiol 2014; 80:3426-32. [PMID: 24657866 DOI: 10.1128/aem.00016-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Efficient degradation of plant polysaccharides in rumen requires xylanolytic enzymes with a high catalytic capacity. In this study, a full-length xylanase gene (xynA) was retrieved from the sheep rumen. The deduced XynA sequence contains a putative signal peptide, a catalytic motif of glycoside hydrolase family 10 (GH10), and an extra C-terminal proline-rich sequence without a homolog. To determine its function, both mature XynA and its C terminus-truncated mutant, XynA-Tr, were expressed in Escherichia coli. The C-terminal oligopeptide had significant effects on the function and structure of XynA. Compared with XynA-Tr, XynA exhibited improved specific activity (12-fold) and catalytic efficiency (14-fold), a higher temperature optimum (50°C versus 45°C), and broader ranges of temperature and pH optima (pH 5.0 to 7.5 and 40 to 60°C versus pH 5.5 to 6.5 and 40 to 50°C). Moreover, XynA released more xylose than XynA-Tr when using beech wood xylan and wheat arabinoxylan as the substrate. The underlying mechanisms responsible for these changes were analyzed by substrate binding assay, circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC), and xylooligosaccharide hydrolysis. XynA had no ability to bind to any of the tested soluble and insoluble polysaccharides. However, it contained more α helices and had a greater affinity and catalytic efficiency toward xylooligosaccharides, which benefited complete substrate degradation. Similar results were obtained when the C-terminal sequence was fused to another GH10 xylanase from sheep rumen. This study reveals an engineering strategy to improve the catalytic performance of enzymes.
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17
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Wan Q, Zhang Q, Hamilton-Brehm S, Weiss K, Mustyakimov M, Coates L, Langan P, Graham D, Kovalevsky A. X-ray crystallographic studies of family 11 xylanase Michaelis and product complexes: implications for the catalytic mechanism. ACTA ACUST UNITED AC 2013; 70:11-23. [PMID: 24419374 DOI: 10.1107/s1399004713023626] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/22/2013] [Indexed: 11/10/2022]
Abstract
Xylanases catalyze the hydrolysis of plant hemicellulose xylan into oligosaccharides by cleaving the main-chain glycosidic linkages connecting xylose subunits. To study ligand binding and to understand how the pH constrains the activity of the enzyme, variants of the Trichoderma reesei xylanase were designed to either abolish its activity (E177Q) or to change its pH optimum (N44H). An E177Q-xylohexaose complex structure was obtained at 1.15 Å resolution which represents a pseudo-Michaelis complex and confirmed the conformational movement of the thumb region owing to ligand binding. Co-crystallization of N44H with xylohexaose resulted in a hydrolyzed xylotriose bound in the active site. Co-crystallization of the wild-type enzyme with xylopentaose trapped an aglycone xylotriose and a transglycosylated glycone product. Replacing amino acids near Glu177 decreased the xylanase activity but increased the relative activity at alkaline pH. The substrate distortion in the E177Q-xylohexaose structure expands the possible conformational itinerary of this xylose ring during the enzyme-catalyzed xylan-hydrolysis reaction.
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Affiliation(s)
- Qun Wan
- Biology and Soft Matter Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Qiu Zhang
- Biology and Soft Matter Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Scott Hamilton-Brehm
- Biosciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Kevin Weiss
- Biology and Soft Matter Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Marat Mustyakimov
- Biology and Soft Matter Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Leighton Coates
- Biology and Soft Matter Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Paul Langan
- Biology and Soft Matter Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - David Graham
- Biosciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Andrey Kovalevsky
- Biology and Soft Matter Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
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18
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Bacik JP, Whitworth GE, Stubbs KA, Vocadlo DJ, Mark BL. Active site plasticity within the glycoside hydrolase NagZ underlies a dynamic mechanism of substrate distortion. ACTA ACUST UNITED AC 2013. [PMID: 23177201 DOI: 10.1016/j.chembiol.2012.09.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
NagZ is a glycoside hydrolase that participates in peptidoglycan (PG) recycling by removing β-N-acetylglucosamine from PG fragments that are excised from the bacterial cell wall during growth. Notably, the products formed by NagZ, 1,6-anhydroMurNAc-peptides, activate β-lactam resistance in many Gram-negative bacteria, making this enzyme of interest as a potential therapeutic target. Crystal structure determinations of NagZ from Salmonella typhimurium and Bacillus subtilis in complex with natural substrate, trapped as a glycosyl-enzyme intermediate, and bound to product, define the reaction coordinate of the NagZ family of enzymes. The structures, combined with kinetic studies, reveal an uncommon degree of structural plasticity within the active site of a glycoside hydrolase, and unveil how NagZ drives substrate distortion using a highly mobile loop that contains a conserved histidine that has been proposed as the general acid/base.
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Affiliation(s)
- John-Paul Bacik
- Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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19
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QM/MM study of catalytic mechanism of Xylanase Cex from Cellulomonas fimi. J Mol Graph Model 2012; 37:67-76. [DOI: 10.1016/j.jmgm.2012.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 04/01/2012] [Accepted: 04/17/2012] [Indexed: 12/13/2022]
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20
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Chen YP, Hwang IE, Lin CJ, Wang HJ, Tseng CP. Enhancing the stability of xylanase from Cellulomonas fimi by cell-surface display on Escherichia coli. J Appl Microbiol 2012; 112:455-63. [DOI: 10.1111/j.1365-2672.2012.05232.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Jordan DB, Braker JD. Opposing influences by subsite −1 and subsite +1 residues on relative xylopyranosidase/arabinofuranosidase activities of bifunctional β-D-xylosidase/α-L-arabinofuranosidase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1648-57. [DOI: 10.1016/j.bbapap.2011.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/16/2011] [Accepted: 08/18/2011] [Indexed: 12/01/2022]
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22
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Functional analysis of hyperthermophilic endocellulase from Pyrococcus horikoshii by crystallographic snapshots. Biochem J 2011; 437:223-30. [PMID: 21557724 DOI: 10.1042/bj20110292] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A hyperthermophilic membrane-related β-1,4-endoglucanase (family 5, cellulase) of the archaeon Pyrococcus horikoshii was found to be capable of hydrolysing cellulose at high temperatures. The hyperthermophilic cellulase has promise for applications in biomass utilization. To clarify its detailed function, we determined the crystal structures of mutants of the enzyme in complex with either the substrate or product ligands. We were able to resolve different kinds of complex structures at 1.65–2.01 Å (1 Å=0.1 nm). The structural analysis of various mutant enzymes yielded a sequence of crystallographic snapshots, which could be used to explain the catalytic process of the enzyme. The substrate position is fixed by the alignment of one cellobiose unit between the two aromatic amino acid residues at subsites +1 and +2. During the enzyme reaction, the glucose structure of cellulose substrates is distorted at subsite −1, and the β-1,4-glucoside bond between glucose moieties is twisted between subsites −1 and +1. Subsite −2 specifically recognizes the glucose residue, but recognition by subsites +1 and +2 is loose during the enzyme reaction. This type of recognition is important for creation of the distorted boat form of the substrate at subsite −1. A rare enzyme–substrate complex was observed within the low-activity mutant Y299F, which suggested the existence of a trapped ligand structure before the formation by covalent bonding of the proposed intermediate structure. Analysis of the enzyme–substrate structure suggested that an incoming water molecule, essential for hydrolysis during the retention process, might be introduced to the cleavage position after the cellobiose product at subsites +1 and +2 was released from the active site.
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23
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Engineering lower inhibitor affinities in β-d-xylosidase of Selenomonas ruminantium by site-directed mutagenesis of Trp145. J Ind Microbiol Biotechnol 2011; 38:1821-35. [DOI: 10.1007/s10295-011-0971-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 04/01/2011] [Indexed: 10/18/2022]
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24
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Witte MD, Walvoort MTC, Li KY, Kallemeijn WW, Donker-Koopman WE, Boot RG, Aerts JMFG, Codée JDC, van der Marel GA, Overkleeft HS. Activity-based profiling of retaining β-glucosidases: a comparative study. Chembiochem 2011; 12:1263-9. [PMID: 21538758 DOI: 10.1002/cbic.201000773] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Indexed: 11/07/2022]
Abstract
Activity-based protein profiling (ABPP) is a versatile strategy to report on enzyme activity in vitro, in situ, and in vivo. The development and use of ABPP tools and techniques has met with considerable success in monitoring physiological processes involving esterases and proteases. Activity-based profiling of glycosidases, on the other hand, has proven more difficult, and to date no broad-spectrum glycosidase activity-based probes (ABPs) have been reported. In a comparative study, we investigated both 2-deoxy-2-fluoroglycosides and cyclitol epoxides for their utility as a starting point towards retaining β-glucosidase ABP. We also investigated the merits of direct labeling and two-step bio-orthogonal labeling in reporting on glucosidase activity under various conditions. Our results demonstrate that 1) in general cyclitol epoxides are the superior glucosidase ABPs, 2) that direct labeling is the more efficient approach but it hinges on the ability of the glucosidase to be accommodated in the active site of the reporter (BODIPY) entity, and 3) that two-step bio-orthogonal labeling can be achieved on isolated enzymes but translating this protocol to cell extracts requires more investigation.
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Affiliation(s)
- Martin D Witte
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
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25
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Abstract
Starch and cellulose are the most abundant and important representatives of renewable biomass. Since the mid-19th century their properties have been changed by chemical modification for commercial and scientific purposes, and there substituted polymers have found a wide range of applications. However, the inherent polydispersity and supramolecular organization of starch and cellulose cause the products resulting from their modification to display high complexity. Chemical composition analysis of these mixtures is therefore a challenging task. Detailed knowledge on substitution patterns is fundamental for understanding structure-property relationships in modified cellulose and starch, and thus also for the improvement of reproducibility and rational design of properties. Substitution patterns resulting from kinetically or thermodynamically controlled reactions show certain preferences for the three available hydroxyl functions in (1→4)-linked glucans. Spurlin, seventy years ago, was the first to describe this in an idealized model, and nowadays this model has been extended and related to the next hierarchical levels, namely, the substituent distribution in and over the polymer chains. This structural complexity, with its implications for data interpretation, and the analytical approaches developed for its investigation are outlined in this article. Strategies and methods for the determination of the average degree of substitution (DS), monomer composition, and substitution patterns at the polymer level are presented and discussed with respect to their limitations and interpretability. Nuclear magnetic resonance spectroscopy, chromatography, capillary electrophoresis, and modern mass spectrometry (MS), including tandem MS, are the main instrumental techniques employed, in combination with appropriate sample preparation by chemical and enzymatic methods.
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26
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27
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Pollet A, Delcour JA, Courtin CM. Structural determinants of the substrate specificities of xylanases from different glycoside hydrolase families. Crit Rev Biotechnol 2010; 30:176-91. [DOI: 10.3109/07388551003645599] [Citation(s) in RCA: 176] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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28
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Jordan DB, Braker JD. β-d-Xylosidase from Selenomonas ruminantium: Role of Glutamate 186 in Catalysis Revealed by Site-Directed Mutagenesis, Alternate Substrates, and Active-Site Inhibitor. Appl Biochem Biotechnol 2010; 161:395-410. [DOI: 10.1007/s12010-009-8874-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2009] [Accepted: 11/25/2009] [Indexed: 10/19/2022]
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29
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An alkaline active xylanase: Insights into mechanisms of high pH catalytic adaptation. Biochimie 2009; 91:1187-96. [DOI: 10.1016/j.biochi.2009.06.017] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 06/18/2009] [Indexed: 11/21/2022]
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30
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Enebro J, Momcilovic D, Siika-Aho M, Karlsson S. Liquid chromatography combined with mass spectrometry for the investigation of endoglucanase selectivity on carboxymethyl cellulose. Carbohydr Res 2009; 344:2173-81. [PMID: 19735910 DOI: 10.1016/j.carres.2009.08.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 08/07/2009] [Accepted: 08/08/2009] [Indexed: 10/20/2022]
Abstract
Endoglucanases are useful tools in the chemical structure analysis of cellulose derivatives. However, knowledge on the endoglucanase selectivity, which is of central importance for data interpretation, is still limited. In this study, new reverse-phase liquid chromatography mass spectrometry (LC-MS) methods were developed to investigate the selectivity of the endoglucanases Cel5A, Cel7B, Cel45A, and Cel74A from the filamentous fungus Trichoderma reesei. The aim was to improve the identification of the regioisomers in the complex mixtures that are obtained after enzymatic hydrolysis. Reduction followed by per-O-methylation was performed in order to improve the separation in reverse-phase LC, increase MS sensitivity, and to facilitate structure analysis by MS/MS of O-carboxymethyl glucose and cellooligosaccharides. The cellulose selective enzymes that were investigated displayed interesting differences in enzyme selectivity on CMC substrates.
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Affiliation(s)
- Jonas Enebro
- School of Chemical Science and Engineering, Fibre and Polymer Technology, Royal Institute of Technology (KTH), Stockholm, Sweden
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31
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Kuntz DA, Liu H, Bols M, Rose DR. The role of the active site Zn in the catalytic mechanism of the GH38 Golgi α-mannosidase II: Implications from noeuromycin inhibition. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420500533242] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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32
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Vasur J, Kawai R, Andersson E, Igarashi K, Sandgren M, Samejima M, Ståhlberg J. X-ray crystal structures of Phanerochaete chrysosporium Laminarinase 16A in complex with products from lichenin and laminarin hydrolysis. FEBS J 2009; 276:3858-69. [PMID: 19769746 DOI: 10.1111/j.1742-4658.2009.07099.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The 1,3(4)-beta-D-glucanases of glycoside hydrolase family 16 provide useful examples of versatile yet specific protein-carbohydrate interactions. In the present study, we report the X-ray structures of the 1,3(4)-beta-D-glucanase Phanerochaete chrysosporium Laminarinase 16A in complex with beta-glucan products from laminarin (1.6 A) and lichenin (1.1 A) hydrolysis. The G6G3G3G glucan, in complex with the enzyme, showed a beta-1,6 branch in the acceptor site. The G4G3G ligand-protein complex showed that there was no room for a beta-1,6 branch in the -1 or -2 subsites; furthermore, the distorted residue in the -1 subsite and the glucose in the -2 subsite required a beta-1,3 bond between them. These are the first X-ray crystal structures of any 1,3(4)-beta-D-glucanase in complex with glucan products. They provide details of both substrate and product binding in support of earlier enzymatic evidence.
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Affiliation(s)
- Jonas Vasur
- Department of Molecular Biology, University of Agricultural Sciences, Uppsala, Sweden
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33
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Abel M, Segade A, Planas A. Synthesis of an aryl 2-deoxy-β-glycosyl tetrasaccharide to probe retaining endo-glycosidase mechanism. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.tetasy.2009.03.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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34
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Suzuki R, Fujimoto Z, Ito S, Kawahara SI, Kaneko S, Taira K, Hasegawa T, Kuno A. Crystallographic snapshots of an entire reaction cycle for a retaining xylanase from Streptomyces olivaceoviridis E-86. J Biochem 2009; 146:61-70. [PMID: 19279191 DOI: 10.1093/jb/mvp047] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Retaining glycosyl hydrolases, which catalyse both glycosylation and deglycosylation in a concerted manner, are the most abundant hydrolases. To date, their visualization has tended to be focused on glycosylation because glycosylation reactions can be visualized by inactivating deglycosylation step and/or using substrate analogues to isolate covalent intermediates. Furthermore, during structural analyses of glycosyl hydrolases with hydrolytic reaction products by the conventional soaking method, mutarotation of an anomeric carbon in the reaction products promptly and certainly occurs. This undesirable structural alteration hinders visualization of the second step in the reaction. Here, we investigated X-ray crystallographic visualization as a possible method for visualizing the conformational itinerary of a retaining xylanase from Streptomyces olivaceoviridis E-86. To clearly define the stereochemistry at the anomeric carbon during the deglycosylation step, extraneous nucleophiles, such as azide, were adopted to substitute for the missing base catalyst in an appropriate mutant. The X-ray crystallographic visualization provided snapshots of the components of the entire reaction, including the E*S complex, the covalent intermediate, breakdown of the intermediate and the enzyme-product (E*P)complex.
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Affiliation(s)
- Ryuichiro Suzuki
- Department of Material and Biological Chemistry, Yamagata University, Japan
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35
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Vocadlo DJ, Davies GJ. Mechanistic insights into glycosidase chemistry. Curr Opin Chem Biol 2009; 12:539-55. [PMID: 18558099 DOI: 10.1016/j.cbpa.2008.05.010] [Citation(s) in RCA: 300] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 05/19/2008] [Indexed: 11/16/2022]
Abstract
The enzymatic hydrolysis of the glycosidic bond continues to gain importance, reflecting the critically important roles complex glycans play in health and disease as well as the rekindled interest in enzymatic biomass conversion. Recent advances include the broadening of our understanding of enzyme reaction coordinates, through both computational and structural studies, improved understanding of enzyme inhibition through transition state mimicry and fascinating insights into mechanism yielded by physical organic chemistry approaches.
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Affiliation(s)
- David J Vocadlo
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Canada.
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36
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Piens K, Fauré R, Sundqvist G, Baumann MJ, Saura-Valls M, Teeri TT, Cottaz S, Planas A, Driguez H, Brumer H. Mechanism-based Labeling Defines the Free Energy Change for Formation of the Covalent Glycosyl-enzyme Intermediate in a Xyloglucan endo-Transglycosylase. J Biol Chem 2008; 283:21864-72. [DOI: 10.1074/jbc.m803057200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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37
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Dechancie J, Clemente FR, Smith AJT, Gunaydin H, Zhao YL, Zhang X, Houk KN. How similar are enzyme active site geometries derived from quantum mechanical theozymes to crystal structures of enzyme-inhibitor complexes? Implications for enzyme design. Protein Sci 2007; 16:1851-66. [PMID: 17766382 PMCID: PMC2206971 DOI: 10.1110/ps.072963707] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Quantum mechanical optimizations of theoretical enzymes (theozymes), which are predicted catalytic arrays of biological functionalities stabilizing a transition state, have been carried out for a set of nine diverse enzyme active sites. For each enzyme, the theozyme for the rate-determining transition state plus the catalytic groups modeled by side-chain mimics was optimized using B3LYP/6-31G(d) or, in one case, HF/3-21G(d) quantum mechanical calculations. To determine if the theozyme can reproduce the natural evolutionary catalytic geometry, the positions of optimized catalytic atoms, i.e., covalent, partial covalent, or stabilizing interactions with transition state atoms, are compared to the positions of the atoms in the X-ray crystal structure with a bound inhibitor. These structure comparisons are contrasted to computed substrate-active site structures surrounded by the same theozyme residues. The theozyme/transition structure is shown to predict geometries of active sites with an average RMSD of 0.64 A from the crystal structure, while the RMSD for the bound intermediate complexes are significantly higher at 1.42 A. The implications for computational enzyme design are discussed.
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Affiliation(s)
- Jason Dechancie
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA
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38
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Enhancement of the thermostability and hydrolytic activity of GH10 xylanase by module shuffling between Cellulomonas fimi Cex and Thermomonospora alba XylA. World J Microbiol Biotechnol 2007. [DOI: 10.1007/s11274-006-9263-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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39
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Meloncelli PJ, Gloster TM, Money VA, Tarling CA, Davies GJ, Withers SG, Stick RV. D-Glucosylated Derivatives of Isofagomine and Noeuromycin and Their Potential as Inhibitors of β-Glycoside Hydrolases. Aust J Chem 2007. [DOI: 10.1071/ch07188] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
While isofagomine and noeuromycin have previously been demonstrated to be effective inhibitors of a range of exo-acting glycosidases, they are usually only very weak inhibitors of endo-glycosidases. However, the disaccharide-like 3- and 4-O-β-d-glucopyranosylisofagomines have proven to be strong inhibitors of these endo-acting enzymes that utilize multiple sub-sites. In an attempt to emulate these successes, we have prepared 3- and 4-O-β-d-glucopyranosylnoeuromycin, the former by a selective glycosylation (at O2) of benzyl 4-C-cyano-4-deoxy-α-d-arabinoside (also leading to another synthesis of 3-O-β-d-glucopyranosylisofagomine), the latter by a non-selective glycosylation of benzyl 4-O-allyl-β-l-xyloside with subsequent introduction of the required nitrile group (also leading to another synthesis of 4-O-β-d-glucopyranosylisofagomine). 3-O-β-d-Glucopyranosylnoeuromycin was evaluated as an inhibitor of a family 26 lichenase from Clostridium thermocellum, and 4-O-β-d-glucopyranosylnoeuromycin as an inhibitor of both a family 5 endo-glucanase from Bacillus agaradhaerans and a family 10 endo-xylanase from Cellulomonas fimi. We also report X-ray structural investigations of 3- and 4-O-β-d-glucopyranosylnoeuromycin in complex with the family 26 and family 5 β-glycoside hydrolases, respectively. The two d-glucosylated noeuromycins were indeed able to harness the additional binding energy from the sub-sites of their endo-glycoside hydrolase targets, and were thus excellent inhibitors (in the nanomolar range), binding as expected in the –1 and –2 sub-sites of the enzymes.
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40
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Williams SJ, Hekmat O, Withers SG. Synthesis and Testing of Mechanism-Based Protein-Profiling Probes for Retaining Endo-glycosidases. Chembiochem 2006; 7:116-24. [PMID: 16397879 DOI: 10.1002/cbic.200500279] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
New functional proteomics methods are required for targeting and identification of subsets of a proteome in an activity-based fashion. Glycosidases play critical roles in biology, yet a robust method for functional analysis of their activities and identities in biological proteomes is still lacking. An aryl 2-deoxy-2-fluoro xylobioside inactivator was conjugated through cleavable and noncleavable linker arms to a biotin tag, thereby yielding two new active-site-directed reagents for activity-based profiling of retaining beta-glycanases in complex proteomes. Crucially, these tagged reagents possess high specificity for their target enzymes with kinetic parameters similar to those of the untagged reagent. Western blotting showed that these reagents bind and covalently label active retaining beta-glycanases both in pure enzyme samples and in the secreted proteome of the soil bacterium Cellulomonas fimi. Such reagents therefore show great promise for future activity-based targeting of glycanases.
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Affiliation(s)
- Spencer J Williams
- Protein Engineering Network of Centres of Excellence of Canada, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
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41
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Vardakou M, Flint J, Christakopoulos P, Lewis RJ, Gilbert HJ, Murray JW. A family 10 Thermoascus aurantiacus xylanase utilizes arabinose decorations of xylan as significant substrate specificity determinants. J Mol Biol 2005; 352:1060-7. [PMID: 16140328 DOI: 10.1016/j.jmb.2005.07.051] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 07/14/2005] [Accepted: 07/19/2005] [Indexed: 10/25/2022]
Abstract
Xylan, which is a key component of the plant cell wall, consists of a backbone of beta-1,4-linked xylose residues that are decorated with arabinofuranose, acetyl, 4-O-methyl d-glucuronic acid and ferulate. The backbone of xylan is hydrolysed by endo-beta1,4-xylanases (xylanases); however, it is unclear whether the various side-chains of the polysaccharide are utilized by these enzymes as significant substrate specificity determinants. To address this question we have determined the crystal structure of a family 10 xylanase from Thermoascus aurantiacus, in complex with xylobiose containing an arabinofuranosyl-ferulate side-chain. We show that the distal glycone subsite of the enzyme makes extensive direct and indirect interactions with the arabinose side-chain, while the ferulate moiety is solvent-exposed. Consistent with the 3D structural data, the xylanase displays fourfold more activity against xylotriose in which the non-reducing moiety is linked to an arabinose side-chain, compared to the undecorated form of the oligosacchairde. These data indicate that the sugar decorations of xylans in the T.aurantiacus family 10 xylanase, rather than simply being accommodated, can be significant substrate specificity determinants.
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Affiliation(s)
- Maria Vardakou
- Biotechnology Laboratory, Chemical Engineering Department, National Technical University of Athens, 5 Iroon Polytechniou Str, Zografou Campus, 15780, Athens, Greece
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Czjzek M, Ben David A, Bravman T, Shoham G, Henrissat B, Shoham Y. Enzyme–Substrate Complex Structures of a GH39 β-Xylosidase from Geobacillus stearothermophilus. J Mol Biol 2005; 353:838-46. [PMID: 16212978 DOI: 10.1016/j.jmb.2005.09.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 08/31/2005] [Accepted: 09/01/2005] [Indexed: 10/25/2022]
Abstract
Beta-D-Xylosidases are glycoside hydrolases that catalyse the release of xylose units from short xylooligosaccharides and are engaged in the final breakdown of plant cell-wall hemicelluloses. beta-D-Xylosidases are found in glycoside hydrolase families 3, 39, 43, 52 and 54. The first crystal structure of a GH39 beta-xylosidase revealed a multi-domain organization with the catalytic domain having the canonical (beta/alpha)8 barrel fold. Here, we report the crystal structure of the GH39 Geobacillus stearothermophilus beta-D-xylosidase, inactivated by a point mutation of the general acid-base residue E160A, in complex with the chromogenic substrate molecule 2,5-dinitrophenyl-beta-D-xyloside. Surprisingly, six of the eight active sites present in the crystallographic asymmetric unit contain the trapped covalent glycosyl-enzyme intermediate, while two of them still contain the uncleaved substrate. The structural characterization of these two critical species along the reaction coordinate of this enzyme identifies the residues forming its xyloside-binding pocket as well as those essential for its aglycone recognition.
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Affiliation(s)
- Mirjam Czjzek
- Station Biologique de Roscoff, Végétaux Marins et Biomolécules, UMR7139-CNRS-UPMC, Place George Teissier, BP74, 29682 Roscoff, France.
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43
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Momcilovic D, Schagerlöf H, Röme D, Jörntén-Karlsson M, Karlsson KE, Wittgren B, Tjerneld F, Wahlund KG, Brinkmalm G. Derivatization Using Dimethylamine for Tandem Mass Spectrometric Structure Analysis of Enzymatically and Acidically Depolymerized Methyl Cellulose. Anal Chem 2005; 77:2948-59. [PMID: 15859615 DOI: 10.1021/ac048194e] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structure analysis of partially depolymerized methyl cellulose was performed by nanoelectrospray ionization tandem mass spectrometry (nano-ESI-MS/MS) and by matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS). Dimethylamine (DMA) was used for the first time as a reducing end derivatization reagent for oligosaccharides. This is an attractive reagent since it could be easily removed from the reaction mixture. Most important it also introduces a basic functional group that increased the sensitivity in both MALDI and nano-ESI. Depolymerization was made in two ways: one by the cellulose selective endoglucanase 5A from Bacillus agaradhaerens (Ba Cel5A) and the other by trifluoroacetic acid. The DMA derivatives formed both protonated and sodiated molecules in nano-ESI and MALDI. Tandem MS of protonated molecules yielded predominantly Y fragments from which the distribution of the substituents in the oligomers could be measured. Fragments obtained in tandem MS of sodiated molecules provided information regarding the positions of the substituents within the anhydroglucose units (AGUs). It was found that Ba Cel5A could cleave glucosidic bonds also if the AGU on the reducing side of the bond was fully methylated. The combination of DMA derivatization and tandem MS was demonstrated as a tool for the characterization of endoglucanase selectivity.
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Affiliation(s)
- Dane Momcilovic
- Department of Technical Analytical Chemistry, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
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44
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Nerinckx W, Desmet T, Piens K, Claeyssens M. An elaboration on thesyn-antiproton donor concept of glycoside hydrolases: electrostatic stabilisation of the transition state as a general strategy. FEBS Lett 2004; 579:302-12. [PMID: 15642336 DOI: 10.1016/j.febslet.2004.12.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Revised: 12/10/2004] [Accepted: 12/10/2004] [Indexed: 11/16/2022]
Abstract
An in silico survey of all known 3D-structures of glycoside hydrolases that contain a ligand in the -1 subsite is presented. A recurrent crucial positioning of active site residues indicates a common general strategy for electrostatic stabilisation directed to the carbohydrate's ring-oxygen at the transition state. This is substantially different depending on whether the enzyme's proton donor is syn or anti positioned versus the substrate. A comprehensive list of enzymes belonging to 42 different families is given and selected examples are described. An implication for an early evolution scenario of glycoside hydrolases is discussed.
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Affiliation(s)
- W Nerinckx
- Laboratory for Glycobiology, Department of Biochemistry, Physiology and Microbiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium.
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45
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Allouch J, Helbert W, Henrissat B, Czjzek M. Parallel substrate binding sites in a beta-agarase suggest a novel mode of action on double-helical agarose. Structure 2004; 12:623-32. [PMID: 15062085 DOI: 10.1016/j.str.2004.02.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Revised: 01/06/2004] [Accepted: 01/06/2004] [Indexed: 11/16/2022]
Abstract
Agarose is a gel-forming polysaccharide with an alpha-L(1,4)-3,6-anhydro-galactose, beta-D(1,3)-galactose repeat unit, from the cell walls of marine red algae. beta-agarase A, from the Gram-negative bacterium Zobellia galactanivorans, is secreted to the external medium and degrades agarose with an endo-mechanism. The structure of the inactive mutant beta-agarase A-E147S in complex with agaro-octaose has been solved at 1.7 A resolution. Two oligosaccharide chains are bound to the protein. The first one resides in the active site channel, spanning subsites -4 to -1. A second oligosaccharide binding site, on the opposite side of the protein, was filled with eight sugar units, parallel to the active site. The crystal structure of the beta-agarase A with agaro-octaose provides detailed information on agarose recognition in the catalytic site. The presence of the second, parallel, binding site suggests that the enzyme might be able to unwind the double-helical structure of agarose prior to the catalytic cleavage.
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Affiliation(s)
- Julie Allouch
- Architecture et Fonction de la Macromolécules Biologiques, UMR 6098, Centre National de la Recherche Scientifique and Universités Aix-Marseille I and II, 31 chemin Joseph Aiguier, F-13402 Marseille Cedex 20, France [corrected]
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46
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Kim YW, Lee SS, Warren RAJ, Withers SG. Directed Evolution of a Glycosynthase from Agrobacterium sp. Increases Its Catalytic Activity Dramatically and Expands Its Substrate Repertoire. J Biol Chem 2004; 279:42787-93. [PMID: 15252054 DOI: 10.1074/jbc.m406890200] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Agrobacterium sp. beta-glucosidase (Abg) is a retaining beta-glycosidase and its nucleophile mutants, termed Abg glycosynthases, catalyze the formation of glycosidic bonds using alpha-glycosyl fluorides as donor sugars and various aryl glycosides as acceptor sugars. Two rounds of random mutagenesis were performed on the best glycosynthase to date (AbgE358G), and transformants were screened using an on-plate endocellulase coupled assay. Two highly active mutants were obtained, 1D12 (A19T, E358G) and 2F6 (A19T, E358G, Q248R, M407V) in the first and second rounds, respectively. Relative catalytic efficiencies (kcat/Km) of 1:7:27 were determined for AbgE358G, 1D12, and 2F6, respectively, using alpha-D-galactopyranosyl fluoride and 4-nitrophenyl beta-D-glucopyranoside as substrates. The 2F6 mutant is not only more efficient but also has an expanded repertoire of acceptable substrates. Analysis of a homology model structure of 2F6 indicated that the A19T and M407V mutations do not interact directly with substrates but exert their effects by changing the conformation of the active site. Much of the improvement associated with the A19T mutation seems to be caused by favorable interactions with the equatorial C2-hydroxyl group of the substrate. The alteration of torsional angles of Glu-411, Trp-412, and Trp-404, which are components of the aglycone (+1) subsite, is an expected consequence of the A19T and M407V mutations based on the homology model structure of 2F6.
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Affiliation(s)
- Young-Wan Kim
- Protein Engineering Network of Centres of Excellence of Canada, British Columbia, Canada
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47
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Verdoucq L, Morinière J, Bevan DR, Esen A, Vasella A, Henrissat B, Czjze M. Structural Determinants of Substrate Specificity in Family 1 β-Glucosidases. J Biol Chem 2004; 279:31796-803. [PMID: 15148317 DOI: 10.1074/jbc.m402918200] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plant beta-glucosidases play a crucial role in defense against pests. They cleave, with variable specificity, beta-glucosides to release toxic aglycone moieties. The Sorghum bicolor beta-glucosidase isoenzyme Dhr1 has a strict specificity for its natural substrate dhurrin (p-hydroxy-(S)-mandelonitrile-beta-D-glucoside), whereas its close homolog, the maize beta-glucosidase isoenzyme Glu1, which shares 72% sequence identity, hydrolyzes a broad spectrum of substrates in addition to its natural substrate 2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxaxin-3-one. Structural data from enzyme.substrate complexes of Dhr1 show that the mode of aglycone binding differs from that previously observed in the homologous maize enzyme. Specifically, the data suggest that Asn(259), Phe(261), and Ser(462), located in the aglycone-binding site of S. bicolor Dhr1, are crucial for aglycone recognition and binding. The tight binding of the aglycone moiety of dhurrin promotes the stabilization of the reaction intermediate in which the glycone moiety is in a deformed (1)S(3) conformation within the glycone-binding site, ready for nucleophilic attack to occur. Compared with the broad specificity maize beta-glucosidase, this different binding mode explains the narrow specificity of sorghum dhurrinase-1.
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Affiliation(s)
- Lionel Verdoucq
- Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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48
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Kaneko S, Ichinose H, Fujimoto Z, Kuno A, Yura K, Go M, Mizuno H, Kusakabe I, Kobayashi H. Structure and function of a family 10 beta-xylanase chimera of Streptomyces olivaceoviridis E-86 FXYN and Cellulomonas fimi Cex. J Biol Chem 2004; 279:26619-26. [PMID: 15078885 DOI: 10.1074/jbc.m308899200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The catalytic domain of xylanases belonging to glycoside hydrolase family 10 (GH10) can be divided into 22 modules (M1 to M22; Sato, Y., Niimura, Y., Yura, K., and Go, M. (1999) Gene (Amst.) 238, 93-101). Inspection of the crystal structure of a GH10 xylanase from Streptomyces olivaceoviridis E-86 (SoXyn10A) revealed that the catalytic domain of GH10 xylanases can be dissected into two parts, an N-terminal larger region and C-terminal smaller region, by the substrate binding cleft, corresponding to the module border between M14 and M15. It has been suggested that the topology of the substrate binding clefts of GH10 xylanases are not conserved (Charnock, S. J., Spurway, T. D., Xie, H., Beylot, M. H., Virden, R., Warren, R. A. J., Hazlewood, G. P., and Gilbert, H. J. (1998) J. Biol. Chem. 273, 32187-32199). To facilitate a greater understanding of the structure-function relationship of the substrate binding cleft of GH10 xylanases, a chimeric xylanase between SoXyn10A and Xyn10A from Cellulomonas fimi (CfXyn10A) was constructed, and the topology of the hybrid substrate binding cleft established. At the three-dimensional level, SoXyn10A and CfXyn10A appear to possess 5 subsites, with the amino acid residues comprising subsites -3 to +1 being well conserved, although the +2 subsites are quite different. Biochemical analyses of the chimeric enzyme along with SoXyn10A and CfXyn10A indicated that differences in the structure of subsite +2 influence bond cleavage frequencies and the catalytic efficiency of xylooligosaccharide hydrolysis. The hybrid enzyme constructed in this study displays fascinating biochemistry, with an interesting combination of properties from the parent enzymes, resulting in a low production of xylose.
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Affiliation(s)
- Satoshi Kaneko
- National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
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Yang JK, Yoon HJ, Ahn HJ, Lee BI, Pedelacq JD, Liong EC, Berendzen J, Laivenieks M, Vieille C, Zeikus GJ, Vocadlo DJ, Withers SG, Suh SW. Crystal structure of beta-D-xylosidase from Thermoanaerobacterium saccharolyticum, a family 39 glycoside hydrolase. J Mol Biol 2004; 335:155-65. [PMID: 14659747 DOI: 10.1016/j.jmb.2003.10.026] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1,4-beta-D-Xylan is the major component of plant cell-wall hemicelluloses. beta-D-Xylosidases are involved in the breakdown of xylans into xylose and belong to families 3, 39, 43, 52, and 54 of glycoside hydrolases. Here, we report the first crystal structure of a member of family 39 glycoside hydrolase, i.e. beta-D-xylosidase from Thermoanaerobacterium saccharolyticum strain B6A-RI. This study also represents the first structure of any beta-xylosidase of the above five glycoside hydrolase families. Each monomer of T. saccharolyticum beta-xylosidase comprises three distinct domains; a catalytic domain of the canonical (beta/alpha)(8)-barrel fold, a beta-sandwich domain, and a small alpha-helical domain. We have determined the structure in two forms: D-xylose-bound enzyme and a covalent 2-deoxy-2-fluoro-alpha-D-xylosyl-enzyme intermediate complex, thus providing two snapshots in the reaction pathway. This study provides structural evidence for the proposed double displacement mechanism that involves a covalent intermediate. Furthermore, it reveals possible functional roles for His228 as the auxiliary acid/base and Glu323 as a key residue in substrate recognition.
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Affiliation(s)
- Jin Kuk Yang
- Structural Proteomics Laboratory, Department of Chemistry, College of Natural Sciences, Seoul National University, 151-742, Seoul, South Korea
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50
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Ogawa M, Nishio T, Hakamata W, Matsuishi Y, Hoshino S, Kondo A, Kitagawa M, Kawachi R, Oku T. Substrate Hydroxyl Groups Are Involved in the Ionization of Catalytic Carboxyl Groups of Aspergillus niger .ALPHA.-Glucosidase. J Appl Glycosci (1999) 2004. [DOI: 10.5458/jag.51.9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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