1
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Tayi L, Nathawat R, Kumar S, Maku RV, Patel HK, Sankaranarayanan R, Sonti RV. Mutational analysis of predicted active site residues of an exoglucanase secreted by Xanthomonas oryzae pv. oryzae to determine their role in catalysis and in virulence on rice. Enzyme Microb Technol 2024; 174:110372. [PMID: 38104475 DOI: 10.1016/j.enzmictec.2023.110372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/04/2023] [Accepted: 12/04/2023] [Indexed: 12/19/2023]
Abstract
Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight disease in rice. As a part of its virulence repertoire, Xoo secretes a cell wall degrading enzyme Cellobiosidase (CbsA), which is a critical virulence factor and also a determinant of tissue specificity. CbsA protein is made up of an N-terminal catalytic domain and a C-terminal fibronectin type III domain. According to the CAZy classification, the catalytic domain of CbsA protein belongs to the glycosyl hydrolase-6 (GH6) family that performs acid-base catalysis. However, the identity of the catalytic acid and the catalytic base of CbsA is not known. Based on the available structural and biochemical data, we identified putative catalytic residues and probed them by site-directed mutagenesis. Intriguingly, the biochemical analysis showed that none of the mutations abolishes the catalytic activity of CbsA, an observation that is contrary to other GH6 family members. All the mutants exhibited altered enzymatic activity and caused significant virulence deficiency in Xoo emphasising the requirement of specific exoglucanase activity of wild-type CbsA for virulence on rice. Our study highlights the need for further studies and the detailed characterisation of bacterial exoglucanases.
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Affiliation(s)
- Lavanya Tayi
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, Telangana 500007, India
| | - Rajkanwar Nathawat
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, Telangana 500007, India
| | - Sushil Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, Telangana 500007, India
| | - Roshan V Maku
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, Telangana 500007, India
| | - Hitendra Kumar Patel
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, Telangana 500007, India
| | - Rajan Sankaranarayanan
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, Telangana 500007, India.
| | - Ramesh V Sonti
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, Telangana 500007, India.
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2
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Nathawat R, Maku RV, Patel HK, Sankaranarayanan R, Sonti RV. Role of the FnIII domain associated with a cell wall-degrading enzyme cellobiosidase of Xanthomonas oryzae pv. oryzae. MOLECULAR PLANT PATHOLOGY 2022; 23:1011-1021. [PMID: 35278018 PMCID: PMC9190976 DOI: 10.1111/mpp.13205] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 02/15/2022] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Cellobiosidase (CbsA) is an important secreted virulence factor of Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial blight of rice. CbsA is one of several cell wall-degrading enzymes secreted by Xoo via the type II secretion system (T2SS). CbsA is considered a fundamental virulence factor for vascular pathogenesis. CbsA has an N-terminal glycosyl hydrolase domain and a C-terminal fibronectin type III (FnIII) domain. Interestingly, the secreted form of CbsA lacks the FnIII domain during in planta growth. Here we show that the presence of the FnIII domain inhibits the enzyme activity of CbsA on polysaccharide substrates like carboxymethylcellulose. The FnIII domain is required for the interaction of CbsA with SecB chaperone, and this interaction is crucial for the stability and efficient transport of CbsA across the inner membrane. Deletion of the FnIII domain reduced virulence similar to ΔcbsA Xoo, which corroborates the importance of the FnIII domain in CbsA. Our work elucidates a hitherto unknown function of the FnIII domain in enabling the virulence-promoting activity of CbsA.
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Affiliation(s)
| | - Roshan V. Maku
- CSIR – Centre for Cellular and Molecular BiologyHyderabadIndia
- Present address:
DBT – National Institute of Animal BiotechnologyHyderabadIndia
| | | | | | - Ramesh V. Sonti
- CSIR – Centre for Cellular and Molecular BiologyHyderabadIndia
- Present address:
Indian Institute of Science Education and Research TirupatiTirupatiIndia
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3
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Alonso‐Gil S, Parkan K, Kaminský J, Pohl R, Miyazaki T. Unlocking the Hydrolytic Mechanism of GH92 α‐1,2‐Mannosidases: Computation Inspires the use of C‐Glycosides as Michaelis Complex Mimics. Chemistry 2022; 28:e202200148. [PMID: 35049087 PMCID: PMC9305736 DOI: 10.1002/chem.202200148] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Indexed: 11/28/2022]
Abstract
The conformational changes in a sugar moiety along the hydrolytic pathway are key to understand the mechanism of glycoside hydrolases (GHs) and to design new inhibitors. The two predominant itineraries for mannosidases go via OS2→B2,5→1S5 and 3S1→3H4→1C4. For the CAZy family 92, the conformational itinerary was unknown. Published complexes of Bacteroides thetaiotaomicron GH92 catalyst with a S‐glycoside and mannoimidazole indicate a 4C1→4H5/1S5→1S5 mechanism. However, as observed with the GH125 family, S‐glycosides may not act always as good mimics of GH's natural substrate. Here we present a cooperative study between computations and experiments where our results predict the E5→B2,5/1S5→1S5 pathway for GH92 enzymes. Furthermore, we demonstrate the Michaelis complex mimicry of a new kind of C‐disaccharides, whose biochemical applicability was still a chimera.
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Affiliation(s)
- Santiago Alonso‐Gil
- Department of Structural and Computational Biology Max F. Perutz Laboratories University of Vienna Dr.-Bohr-Gasse 9 1030 Vienna Austria
| | - Kamil Parkan
- Department of Chemistry of Natural Compounds University of Chemistry and Technology Technická 5 166 28 Prague Czech Republic
| | - Jakub Kaminský
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Gilead Sciences & IOCB Research Centre Czech Academy of Sciences Flemingovo nám. 2 166 10 Prague Czech Republic
| | - Radek Pohl
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Gilead Sciences & IOCB Research Centre Czech Academy of Sciences Flemingovo nám. 2 166 10 Prague Czech Republic
| | - Takatsugu Miyazaki
- Research Institute of Green Science and Technology Shizuoka University 836 Ohya, Suruga-ku Shizuoka 422-8529 Japan
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4
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Fungal cellulases: protein engineering and post-translational modifications. Appl Microbiol Biotechnol 2021; 106:1-24. [PMID: 34889986 DOI: 10.1007/s00253-021-11723-y] [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: 08/28/2021] [Revised: 11/28/2021] [Accepted: 11/30/2021] [Indexed: 12/18/2022]
Abstract
Enzymatic degradation of lignocelluloses into fermentable sugars to produce biofuels and other biomaterials is critical for environmentally sustainable development and energy resource supply. However, there are problems in enzymatic cellulose hydrolysis, such as the complex cellulase composition, low degradation efficiency, high production cost, and post-translational modifications (PTMs), all of which are closely related to specific characteristics of cellulases that remain unclear. These problems hinder the practical application of cellulases. Due to the rapid development of computer technology in recent years, computer-aided protein engineering is being widely used, which also brings new opportunities for the development of cellulases. Especially in recent years, a large number of studies have reported on the application of computer-aided protein engineering in the development of cellulases; however, these articles have not been systematically reviewed. This article focused on the aspect of protein engineering and PTMs of fungal cellulases. In this manuscript, the latest literatures and the distribution of potential sites of cellulases for engineering have been systematically summarized, which provide reference for further improvement of cellulase properties. KEY POINTS: •Rational design based on virtual mutagenesis can improve cellulase properties. •Modifying protein side chains and glycans helps obtain superior cellulases. •N-terminal glutamine-pyroglutamate conversion stabilizes fungal cellulases.
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5
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Alonso‐Gil S. MonteCarbo: A software to generate and dock multifunctionalized ring molecules. J Comput Chem 2021; 42:1526-1534. [PMID: 33982793 PMCID: PMC8359999 DOI: 10.1002/jcc.26559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 04/25/2021] [Accepted: 04/28/2021] [Indexed: 02/01/2023]
Abstract
MonteCarbo is an open-source software to construct simple 5-, 6-, and 7-membered ring multifunctionalized monosaccharides and nucleobases and dock them into the active site of carbohydrate-active enzymes. The core bash script executes simple orders to generate the Z-matrix of the neutral molecule of interest. After that, a Fortran90 code based on a pseudo-random number generator (Monte Carlo method) is executed to assign dihedral angles to the different rotamers present in the structure (ring and rotating functional groups). The program also has a generalized internal coordinates (GIC) implementation of the Cremer and Pople puckering coordinates ring. Once the structures are generated and optimized, a second code is ready to execute in serial the docking of multiple conformers in the active site of a wide family of enzymes.
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Affiliation(s)
- Santiago Alonso‐Gil
- Department of Structural and Computational Biology, Max F. Perutz LaboratoriesUniversity of ViennaViennaAustria
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6
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Kari J, Molina GA, Schaller KS, Schiano-di-Cola C, Christensen SJ, Badino SF, Sørensen TH, Røjel NS, Keller MB, Sørensen NR, Kolaczkowski B, Olsen JP, Krogh KBRM, Jensen K, Cavaleiro AM, Peters GHJ, Spodsberg N, Borch K, Westh P. Physical constraints and functional plasticity of cellulases. Nat Commun 2021; 12:3847. [PMID: 34158485 PMCID: PMC8219668 DOI: 10.1038/s41467-021-24075-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 05/17/2021] [Indexed: 11/16/2022] Open
Abstract
Enzyme reactions, both in Nature and technical applications, commonly occur at the interface of immiscible phases. Nevertheless, stringent descriptions of interfacial enzyme catalysis remain sparse, and this is partly due to a shortage of coherent experimental data to guide and assess such work. In this work, we produced and kinetically characterized 83 cellulases, which revealed a conspicuous linear free energy relationship (LFER) between the substrate binding strength and the activation barrier. The scaling occurred despite the investigated enzymes being structurally and mechanistically diverse. We suggest that the scaling reflects basic physical restrictions of the hydrolytic process and that evolutionary selection has condensed cellulase phenotypes near the line. One consequence of the LFER is that the activity of a cellulase can be estimated from its substrate binding strength, irrespectively of structural and mechanistic details, and this appears promising for in silico selection and design within this industrially important group of enzymes.
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Affiliation(s)
- Jeppe Kari
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Gustavo A Molina
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Kay S Schaller
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Corinna Schiano-di-Cola
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Stefan J Christensen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Silke F Badino
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | | | - Nanna S Røjel
- Department of Science and Environment, Roskilde University, Universitetsvej 1, Roskilde, Denmark
| | - Malene B Keller
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg C, Denmark
| | - Nanna Rolsted Sørensen
- Department of Science and Environment, Roskilde University, Universitetsvej 1, Roskilde, Denmark
| | - Bartlomiej Kolaczkowski
- Department of Science and Environment, Roskilde University, Universitetsvej 1, Roskilde, Denmark
| | | | | | | | | | - Günther H J Peters
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
| | | | | | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark.
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7
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Pereira CS, Silveira RL, Skaf MS. QM/MM Simulations of Enzymatic Hydrolysis of Cellulose: Probing the Viability of an Endocyclic Mechanism for an Inverting Cellulase. J Chem Inf Model 2021; 61:1902-1912. [PMID: 33760586 PMCID: PMC8154253 DOI: 10.1021/acs.jcim.0c01380] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Glycoside hydrolases
(GH) cleave carbohydrate glycosidic bonds
and play pivotal roles in living organisms and in many industrial
processes. Unlike acid-catalyzed hydrolysis of carbohydrates in solution,
which can occur either via cyclic or acyclic oxocarbenium-like transition
states, it is widely accepted that GH-catalyzed hydrolysis proceeds
via a general acid mechanism involving a cyclic oxocarbenium-like
transition state with protonation of the glycosidic oxygen. The GH45
subfamily C inverting endoglucanase from Phanerochaete chrysosporium (PcCel45A) defies the classical inverting mechanism as its crystal
structure conspicuously lacks a general Asp or Glu base residue. Instead,
PcCel45A has an Asn residue, a notoriously weak base in solution,
as one of its catalytic residues at position 92. Moreover, unlike
other inverting GHs, the relative position of the catalytic residues
in PcCel45A impairs the proton abstraction from the nucleophilic water
that attacks the anomeric carbon, a key step in the classical mechanism.
Here, we investigate the viability of an endocyclic mechanism for
PcCel45A using hybrid quantum mechanics/molecular mechanics (QM/MM)
simulations, with the QM region treated with the self-consistent-charge
density-functional tight-binding level of theory. In this mechanism,
an acyclic oxocarbenium-like transition state is stabilized leading
to the opening of the glucopyranose ring and formation of an unstable
acyclic hemiacetal that can be readily decomposed into hydrolysis
product. In silico characterization of the Michaelis
complex shows that PcCel45A significantly restrains the sugar ring
to the 4C1 chair conformation at the −1
subsite of the substrate binding cleft, in contrast to the classical
exocyclic mechanism in which ring puckering is critical. We also show
that PcCel45A provides an environment where the catalytic Asn92 residue
in its standard amide form participates in a cooperative hydrogen
bond network resulting in its increased nucleophilicity due to an
increased negative charge on the oxygen atom. Our results for PcCel45A
suggest that carbohydrate hydrolysis catalyzed by GHs may take an
alternative route from the classical mechanism.
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Affiliation(s)
- Caroline S Pereira
- Institute of Chemistry and Center for Computing in Engineering and Sciences, University of Campinas-Unicamp, Campinas 13084-862, Sao Paulo, Brazil
| | - Rodrigo L Silveira
- Institute of Chemistry and Center for Computing in Engineering and Sciences, University of Campinas-Unicamp, Campinas 13084-862, Sao Paulo, Brazil.,Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-909, Rio de Janeiro, Brazil
| | - Munir S Skaf
- Institute of Chemistry and Center for Computing in Engineering and Sciences, University of Campinas-Unicamp, Campinas 13084-862, Sao Paulo, Brazil
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8
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Abstract
Some cellulases exhibit “processivity”: the ability to degrade crystalline cellulose through successive hydrolytic catalytic reactions without the release of the enzyme from the substrate surface. We previously observed the movement of fungal processive cellulases by high-speed atomic force microscopy, and here, we use the same technique to directly observe the processive movement of bacterial cellobiohydrolases settling a long-standing controversy. Although fungal and bacterial processive cellulases have completely different protein folds, they have evolved to acquire processivity through the same strategy of adding subsites to extend the substrate-binding site and forming a tunnel-like active site by increasing the number of loops covering the active site. This represents an example of protein-level convergent evolution to acquire the same functions from different ancestors. Cellulose is the most abundant biomass on Earth, and many microorganisms depend on it as a source of energy. It consists mainly of crystalline and amorphous regions, and natural degradation of the crystalline part is highly dependent on the degree of processivity of the degrading enzymes (i.e., the extent of continuous hydrolysis without detachment from the substrate cellulose). Here, we report high-speed atomic force microscopic (HS-AFM) observations of the movement of four types of cellulases derived from the cellulolytic bacteria Cellulomonas fimi on various insoluble cellulose substrates. The HS-AFM images clearly demonstrated that two of them (CfCel6B and CfCel48A) slide on crystalline cellulose. The direction of processive movement of CfCel6B is from the nonreducing to the reducing end of the substrate, which is opposite that of processive cellulase Cel7A of the fungus Trichoderma reesei (TrCel7A), whose movement was first observed by this technique, while CfCel48A moves in the same direction as TrCel7A. When CfCel6B and TrCel7A were mixed on the same substrate, “traffic accidents” were observed, in which the two cellulases blocked each other’s progress. The processivity of CfCel6B was similar to those of fungal family 7 cellulases but considerably higher than those of fungal family 6 cellulases. The results indicate that bacteria utilize family 6 cellulases as high-processivity enzymes for efficient degradation of crystalline cellulose, whereas family 7 enzymes have the same function in fungi. This is consistent with the idea of convergent evolution of processive cellulases in fungi and bacteria to achieve similar functionality using different protein foldings.
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9
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Stanisci A, Tøndervik A, Gaardløs M, Lervik A, Skjåk-Bræk G, Sletta H, Aachmann FL. Identification of a Pivotal Residue for Determining the Block Structure-Forming Properties of Alginate C-5 Epimerases. ACS OMEGA 2020; 5:4352-4361. [PMID: 32149266 PMCID: PMC7057702 DOI: 10.1021/acsomega.9b04490] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 02/11/2020] [Indexed: 05/13/2023]
Abstract
Alginate is a linear copolymer composed of 1→4 linked β-d-mannuronic acid (M) and its epimer α-l-guluronic acid (G). The polysaccharide is first produced as homopolymeric mannuronan and subsequently, at the polymer level, C-5 epimerases convert M residues to G residues. The bacterium Azotobacter vinelandii encodes a family of seven secreted and calcium ion-dependent mannuronan C-5 epimerases (AlgE1-AlgE7). These epimerases consist of two types of structural modules: the A-modules, which contain the catalytic site, and the R-modules, which influence activity through substrate and calcium binding. In this study, we rationally designed new hybrid mannuronan C-5 epimerases constituting the A-module from AlgE6 and the R-module from AlgE4. This led to a better understanding of the molecular mechanism determining differences in MG- and GG-block-forming properties of the enzymes. A long loop with either tyrosine or phenylalanine extruding from the β-helix of the enzyme proved essential in defining the final alginate block structure, probably by affecting substrate binding. Normal mode analysis of the A-module from AlgE6 supports the results.
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Affiliation(s)
- Annalucia Stanisci
- Department
of Biotechnology and Food Science, NTNU
Norwegian University of Science and Technology, Norwegian Biopolymer
Laboratory (NOBIPOL), Sem Sælands vei 6/8, NO 7491 Trondheim, Norway
| | - Anne Tøndervik
- Department
of Biotechnology and Nanomedicine, SINTEF
Industry, Richard Birkelands
veg 3 B, NO 7491 Trondheim, Norway
| | - Margrethe Gaardløs
- Department
of Biotechnology and Food Science, NTNU
Norwegian University of Science and Technology, Norwegian Biopolymer
Laboratory (NOBIPOL), Sem Sælands vei 6/8, NO 7491 Trondheim, Norway
| | - Anders Lervik
- Department
of Chemistry, NTNU Norwegian University
of Science and Technology, Høgskoleringen 5, NO 7491 Trondheim, Norway
| | - Gudmund Skjåk-Bræk
- Department
of Biotechnology and Food Science, NTNU
Norwegian University of Science and Technology, Norwegian Biopolymer
Laboratory (NOBIPOL), Sem Sælands vei 6/8, NO 7491 Trondheim, Norway
| | - Håvard Sletta
- Department
of Biotechnology and Nanomedicine, SINTEF
Industry, Richard Birkelands
veg 3 B, NO 7491 Trondheim, Norway
| | - Finn L. Aachmann
- Department
of Biotechnology and Food Science, NTNU
Norwegian University of Science and Technology, Norwegian Biopolymer
Laboratory (NOBIPOL), Sem Sælands vei 6/8, NO 7491 Trondheim, Norway
- E-mail: . Phone: +4773593317. Fax: +4773591283
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10
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Sørlie M, Horn SJ, Vaaje-Kolstad G, Eijsink VG. Using chitosan to understand chitinases and the role of processivity in the degradation of recalcitrant polysaccharides. REACT FUNCT POLYM 2020. [DOI: 10.1016/j.reactfunctpolym.2020.104488] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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11
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Røjel N, Kari J, Sørensen TH, Borch K, Westh P. pH profiles of cellulases depend on the substrate and architecture of the binding region. Biotechnol Bioeng 2019; 117:382-391. [PMID: 31631319 DOI: 10.1002/bit.27206] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 09/09/2019] [Accepted: 10/13/2019] [Indexed: 01/06/2023]
Abstract
Understanding the pH effect of cellulolytic enzymes is of great technological importance. In this study, we have examined the influence of pH on activity and stability for central cellulases (Cel7A, Cel7B, Cel6A from Trichoderma reesei, and Cel7A from Rasamsonia emersonii). We systematically changed pH from 2 to 7, temperature from 20°C to 70°C, and used both soluble (4-nitrophenyl β- d-lactopyranoside [pNPL]) and insoluble (Avicel) substrates at different concentrations. Collective interpretation of these data provided new insights. An unusual tolerance to acidic conditions was observed for both investigated Cel7As, but only on real insoluble cellulose. In contrast, pH profiles on pNPL were bell-shaped with a strong loss of activity both above and below the optimal pH for all four enzymes. On a practical level, these observations call for the caution of the common practice of using soluble substrates for the general characterization of pH effects on cellulase activity. Kinetic modeling of the experimental data suggested that the nucleophile of Cel7A experiences a strong downward shift in pKa upon complexation with an insoluble substrate. This shift was less pronounced for Cel7B, Cel6A, and for Cel7A acting on the soluble substrate, and we hypothesize that these differences are related to the accessibility of water to the binding region of the Michaelis complex.
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Affiliation(s)
- Nanna Røjel
- Department of Science and Environment (INM), Roskilde University, Roskilde, Denmark.,Present address: Department of Biotechnology and Biomedicine, Technical University of Denmark, Building 224, DK-2800, Kgs. Lyngby, Denmark
| | - Jeppe Kari
- Department of Science and Environment (INM), Roskilde University, Roskilde, Denmark.,Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | | | | | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
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12
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Huang HC, Qi LH, Chen YC, Tsai LC. Crystal structures of the GH6 Orpinomyces sp. Y102 CelC7 enzyme with exo and endo activity and its complex with cellobiose. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2019; 75:1138-1147. [PMID: 31793907 DOI: 10.1107/s2059798319013597] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 10/04/2019] [Indexed: 11/10/2022]
Abstract
The catalytic domain (residues 128-449) of the Orpinomyces sp. Y102 CelC7 enzyme (Orp CelC7) exhibits cellobiohydrolase and cellotriohydrolase activities. Crystal structures of Orp CelC7 and its cellobiose-bound complex have been solved at resolutions of 1.80 and 2.78 Å, respectively. Cellobiose occupies subsites +1 and +2 within the active site of Orp CelC7 and forms hydrogen bonds to two key residues: Asp248 and Asp409. Furthermore, its substrate-binding sites have both tunnel-like and open-cleft conformations, suggesting that the glycoside hydrolase family 6 (GH6) Orp CelC7 enzyme may perform enzymatic hydrolysis in the same way as endoglucanases and cellobiohydrolases. LC-MS/MS analysis revealed cellobiose (major) and cellotriose (minor) to be the respective products of endo and exo activity of the GH6 Orp CelC7.
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Affiliation(s)
- Hsiao Chuan Huang
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei, Taiwan
| | - Liu Hong Qi
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei, Taiwan
| | - Yo Chia Chen
- Department of Biological Science and Technology, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Li Chu Tsai
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei, Taiwan
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13
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Lin L, Qin N, Guan L. A Novel Cold-adapted Endoglucanase (M6A) from Microbacterium kitamiense S12 Isolated from Qinghai-Tibetan Plateau. BIOTECHNOL BIOPROC E 2019. [DOI: 10.1007/s12257-019-0009-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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14
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Christensen SJ, Kari J, Badino SF, Borch K, Westh P. Rate‐limiting step and substrate accessibility of cellobiohydrolase Cel6A from
Trichoderma reesei. FEBS J 2018; 285:4482-4493. [DOI: 10.1111/febs.14668] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 09/11/2018] [Accepted: 09/28/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Stefan J. Christensen
- Research Unit for Functional Biomaterials Department of Science and Environment Roskilde University Denmark
| | - Jeppe Kari
- Research Unit for Functional Biomaterials Department of Science and Environment Roskilde University Denmark
| | - Silke F. Badino
- Research Unit for Functional Biomaterials Department of Science and Environment Roskilde University Denmark
| | | | - Peter Westh
- Research Unit for Functional Biomaterials Department of Science and Environment Roskilde University Denmark
- Department of Biotechnology and Biomedicine Technical University of Denmark Lyngby Denmark
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15
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Oyeleye A, Normi YM. Chitinase: diversity, limitations, and trends in engineering for suitable applications. Biosci Rep 2018; 38:BSR2018032300. [PMID: 30042170 PMCID: PMC6131217 DOI: 10.1042/bsr20180323] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 06/07/2018] [Accepted: 12/07/2018] [Indexed: 01/09/2023] Open
Abstract
Chitinases catalyze the degradation of chitin, a ubiquitous polymer generated from the cell walls of fungi, shells of crustaceans, and cuticles of insects. They are gaining increasing attention in medicine, agriculture, food and drug industries, and environmental management. Their roles in the degradation of chitin for the production of industrially useful products and in the control of fungal pathogens and insect pests render them attractive for such purposes. However, chitinases have diverse sources, characteristics, and mechanisms of action that seem to restrain optimization procedures and render standardization techniques for enhanced practical applications complex. Hence, results of laboratory trials are not usually consistent with real-life applications. With the growing field of protein engineering, these complexities can be overcome by modifying or redesigning chitinases to enhance specific features required for specific applications. In this review, the variations in features and mechanisms of chitinases that limit their exploitation in biotechnological applications are compiled. Recent attempts to engineer chitinases for improved efficiency are also highlighted.
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Affiliation(s)
- Ayokunmi Oyeleye
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia
| | - Yahaya M Normi
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Malaysia
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16
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Tayi L, Kumar S, Nathawat R, Haque AS, Maku RV, Patel HK, Sankaranarayanan R, Sonti RV. A mutation in an exoglucanase of Xanthomonas oryzae pv. oryzae, which confers an endo mode of activity, affects bacterial virulence, but not the induction of immune responses, in rice. MOLECULAR PLANT PATHOLOGY 2018; 19:1364-1376. [PMID: 28976110 PMCID: PMC6638110 DOI: 10.1111/mpp.12620] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/16/2017] [Accepted: 09/29/2017] [Indexed: 05/08/2023]
Abstract
Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight, a serious disease of rice. Xoo secretes a repertoire of cell wall-degrading enzymes, including cellulases, xylanases and pectinases, to degrade various polysaccharide components of the rice cell wall. A secreted Xoo cellulase, CbsA, is not only a key virulence factor of Xoo, but is also a potent inducer of innate immune responses of rice. In this study, we solved the crystal structure of the catalytic domain of the CbsA protein to a resolution of 1.86 Å. The core structure of CbsA shows a central distorted TIM barrel made up of eight β strands with N- and C-terminal loops enclosing the active site, which is a characteristic structural feature of an exoglucanase. The aspartic acid at the 131st position of CbsA was predicted to be important for catalysis and was therefore mutated to alanine to study its role in the catalysis and biological functions of CbsA. Intriguingly, the D131A CbsA mutant protein displayed the enzymatic activity of a typical endoglucanase. D131A CbsA was as proficient as wild-type (Wt) CbsA in inducing rice immune responses, but was deficient in virulence-promoting activity. This indicates that the specific exoglucanase activity of the Wt CbsA protein is required for this protein to promote the growth of Xoo in rice.
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Affiliation(s)
- Lavanya Tayi
- CSIR‐Centre for Cellular and Molecular BiologyHyderabad 500007India
- Present address:
Centre for Plant Molecular BiologyOsmania UniversityHyderabad 500007India
| | - Sushil Kumar
- CSIR‐Centre for Cellular and Molecular BiologyHyderabad 500007India
- Present address:
Institute of Life SciencesNalco SquareBhuvaneshwar 751023India
| | | | - Asfarul S. Haque
- CSIR‐Centre for Cellular and Molecular BiologyHyderabad 500007India
- Present address:
Department of BiochemistryMcGill UniversityMontréalQC H3G 0B1Canada
| | - Roshan V. Maku
- CSIR‐Centre for Cellular and Molecular BiologyHyderabad 500007India
| | | | | | - Ramesh V. Sonti
- CSIR‐Centre for Cellular and Molecular BiologyHyderabad 500007India
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17
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Rani A, Dhillon A, Sharma K, Goyal A. Insights into the structural characteristics and substrate binding analysis of chondroitin AC lyase (PsPL8A) from Pedobacter saltans. Int J Biol Macromol 2018; 109:980-991. [PMID: 29155196 DOI: 10.1016/j.ijbiomac.2017.11.087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 11/12/2017] [Accepted: 11/13/2017] [Indexed: 10/18/2022]
Abstract
The structure of chondroitin AC lyase (PsPL8A) of family 8 polysaccharide lyase was characterized. Modeled PsPL8A structure showed, it contains N-terminal (α/α)6 incomplete toroidal fold and a layered β sandwich structure at C-terminal. Ramchandran plot displayed 98.5% residues in favoured and 1.2% in generously allowed region. Secondary structure of PsPL8A by CD revealed 27.31% α helices 22.7% β sheets and 49.9% random coils. Protein melting study showed, PsPL8A completely unfolds at 60°C. SAXS analysis showed, PsPL8A is fully folded in solution form. The ab initio derived dummy model of PsPL8A superposed well with its modeled structure excluding some α-helices and loop region. Structural superposition and docking analysis showed, N153, W105, H203, Y208, Y212, R266 and E349 were involved in catalysis. Mutants N153A, H203A, Y212F, R266A and E349A created by SDM revealed no residual activity. Isothermal titration calorimetry analysis of Y212F and H203A with C4S polysaccharide, showed moderate binding by Y212F (Ka=9.56±3.81×105) and no binding with H203A, showing active contribution of Y212 in substrate binding. Residues Y212 and H203 or R266 might act as general base and general acid respectively. Residues N153 and E349 are likely contributing in charge neutralization and stabilizing enolate anion intermediate during β-elimination.
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Affiliation(s)
- Aruna Rani
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Arun Dhillon
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Kedar Sharma
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Arun Goyal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
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18
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Burgin T, Ståhlberg J, Mayes HB. Advantages of a distant cellulase catalytic base. J Biol Chem 2018; 293:4680-4687. [PMID: 29321205 PMCID: PMC5880141 DOI: 10.1074/jbc.ra117.001186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/02/2018] [Indexed: 11/06/2022] Open
Abstract
The inverting glycoside hydrolase Trichoderma reesei (Hypocrea jecorina) Cel6A is a promising candidate for protein engineering for more economical production of biofuels. Until recently, its catalytic mechanism had been uncertain: The best candidate residue to serve as a catalytic base, Asp-175, is farther from the glycosidic cleavage site than in other glycoside hydrolase enzymes. Recent unbiased transition path sampling simulations revealed the hydrolytic mechanism for this more distant base, employing a water wire; however, it is not clear why the enzyme employs a more distant catalytic base, a highly conserved feature among homologs across different kingdoms. In this work, we describe molecular dynamics simulations designed to uncover how a base with a longer side chain, as in a D175E mutant, affects procession and active site alignment in the Michaelis complex. We show that the hydrogen bond network is tuned to the shorter aspartate side chain, and that a longer glutamate side chain inhibits procession as well as being less likely to adopt a catalytically productive conformation. Furthermore, we draw comparisons between the active site in Trichoderma reesei Cel6A and another inverting, processive cellulase to deduce the contribution of the water wire to the overall enzyme function, revealing that the more distant catalytic base enhances product release. Our results can inform efforts in the study and design of enzymes by demonstrating how counterintuitive sacrifices in chemical reactivity can have worthwhile benefits for other steps in the catalytic cycle.
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Affiliation(s)
- Tucker Burgin
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, 48109
| | - Jerry Ståhlberg
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - Heather B Mayes
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, 48109.
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Huang H, Han F, Guan S, Qian M, Wan Y, Shan Y, Zhang H, Wang S. Insight into the process of product expulsion in cellobiohydrolase Cel6A from Trichoderma reesei by computational modeling. J Biomol Struct Dyn 2018. [PMID: 29519213 DOI: 10.1080/07391102.2018.1450164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Glycoside hydrolase cellulase family 6 from Trichoderma reesei (TrCel6A) is an important cellobiohydrolase to hydrolyze cellooligosaccharide into cellobiose. The knowledge of enzymatic mechanisms is critical for improving the conversion efficiency of cellulose into ethanol or other chemicals. However, the process of product expulsion, a key component of enzymatic depolymerization, from TrCel6A has not yet been described in detail. Here, conventional molecular dynamics and steered molecular dynamics (SMD) were applied to study product expulsion from TrCel6A. Tyr103 may be a crucial residue in product expulsion given that it exhibits two different posthydrolytic conformations. In one conformation, Tyr103 rotates to open the -3 subsite. However, Tyr103 does not rotate in the other conformation. Three different routes for product expulsion were proposed on the basis of the two different conformations. The total energy barriers of the three routes were calculated through SMD simulations. The total energy barrier of product expulsion through Route 1, in which Tyr103 does not rotate, was 22.2 kcal·mol-1. The total energy barriers of product expulsion through Routes 2 and 3, in which Tyr103 rotates to open the -3 subsite, were 10.3 and 14.4 kcal·mol-1, respectively. Therefore, Routes 2 and 3 have lower energy barriers than Route 1, and Route 2 is the thermodynamically optimal route for product expulsion. Consequently, the rotation of Tyr103 may be crucial for product release from TrCel6A. Results of this work have potential applications in cellulase engineering.
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Affiliation(s)
- Houhou Huang
- a Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry , Jilin University , Changchun 130023 , People's Republic of China
| | - Fei Han
- a Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry , Jilin University , Changchun 130023 , People's Republic of China
| | - Shanshan Guan
- a Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry , Jilin University , Changchun 130023 , People's Republic of China.,b National Engineering Laboratory for AIDS Vaccine, School of Life Sciences , Jilin University , Changchun 130012 , People's Republic of China
| | - Mengdan Qian
- c State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering , Jilin University , Changchun , Jilin 130012 , People's Republic of China
| | - Yongfeng Wan
- a Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry , Jilin University , Changchun 130023 , People's Republic of China
| | - Yaming Shan
- b National Engineering Laboratory for AIDS Vaccine, School of Life Sciences , Jilin University , Changchun 130012 , People's Republic of China
| | - Hao Zhang
- a Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry , Jilin University , Changchun 130023 , People's Republic of China
| | - Song Wang
- a Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry , Jilin University , Changchun 130023 , People's Republic of China
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20
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Zheng F, Tu T, Wang X, Wang Y, Ma R, Su X, Xie X, Yao B, Luo H. Enhancing the catalytic activity of a novel GH5 cellulase GtCel5 from Gloeophyllum trabeum CBS 900.73 by site-directed mutagenesis on loop 6. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:76. [PMID: 29588661 PMCID: PMC5863444 DOI: 10.1186/s13068-018-1080-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 03/14/2018] [Indexed: 05/17/2023]
Abstract
BACKGROUND Cellulases of glycosyl hydrolase (GH) family 5 share a (β/α)8 TIM-barrel fold structure with eight βα loops surrounding the catalytic pocket. These loops exposed on the surface play a vital role in protein functions, primarily due to the interactions of some key amino acids with solvent and ligand molecules. It has been reported that motions of these loops facilitate substrate access and product release, and loops 6 and 7 located at the substrate entrance of the binding pocket promote proton transfer reaction at the catalytic site motions. However, the role of these flexible loops in catalysis of GH5 cellulase remains to be explored. RESULTS In the present study, an acidic, mesophilic GH5 cellulase (with optimal activity at pH 4.0 and 70 °C), GtCel5, was identified in Gloeophyllum trabeum CBS 900.73. The specific activities of GtCel5 toward CMC-Na, barley β-glucan, and lichenan were 1117 ± 43, 6257 ± 26 and 5318 ± 54 U/mg, respectively. Multiple sequence alignment indicates that one amino acid residue at position 233 on the loop 6 shows semi-conservativeness and might contribute to the great catalytic performance. Saturation mutagenesis at position 233 was then conducted to reveal the vital roles of this position in enzyme properties. In comparison to the wild type, variants N233A and N233G showed decreased optimal temperature (- 10 °C) but increased activities (27 and 70%) and catalytic efficiencies (kcat/Km; 45 and 52%), respectively. The similar roles of position 233 in catalytic performance were also verified in the other two GH5 homologs, TeEgl5A and PoCel5, by reverse mutation. Further molecular dynamics simulations suggested that the substitution of asparagine with alanine or glycine may introduce more hydrogen bonds, increase the flexibility of loop 6, enhance the interactions between enzyme and substrate, and thus improve the substrate affinity and catalytic efficiency. CONCLUSION This study proposed a novel cellulase with potentials for industrial application. A specific position was identified to play key roles in cellulase-substrate interactions and enzyme catalysis. It is of great importance for understanding the binding mechanism of GH5 cellulases, and provides an effective strategy to improve the catalytic performance of cellulases.
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Affiliation(s)
- Fei Zheng
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083 People’s Republic of China
| | - Tao Tu
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Xiaoyu Wang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083 People’s Republic of China
| | - Yuan Wang
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Rui Ma
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Xiaoyun Su
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Xiangming Xie
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083 People’s Republic of China
| | - Bin Yao
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Huiying Luo
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
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21
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Badino SF, Kari J, Christensen SJ, Borch K, Westh P. Direct kinetic comparison of the two cellobiohydrolases Cel6A and Cel7A from Hypocrea jecorina. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1739-1745. [DOI: 10.1016/j.bbapap.2017.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/25/2017] [Accepted: 08/14/2017] [Indexed: 01/17/2023]
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22
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Hamre AG, Frøberg EE, Eijsink VGH, Sørlie M. Thermodynamics of tunnel formation upon substrate binding in a processive glycoside hydrolase. Arch Biochem Biophys 2017; 620:35-42. [PMID: 28359644 DOI: 10.1016/j.abb.2017.03.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/20/2017] [Accepted: 03/23/2017] [Indexed: 11/18/2022]
Abstract
Glycoside hydrolases (GHs) catalyze the hydrolysis of glycosidic bonds and are key enzymes in carbohydrate metabolism. Efficient degradation of recalcitrant polysaccharides such as chitin and cellulose is accomplished due to synergistic enzyme cocktails consisting of accessory enzymes and mixtures of GHs with different modes of action and active site topologies. The substrate binding sites of chitinases and cellulases often have surface exposed aromatic amino acids and a tunnel or cleft topology. The active site of the exo-processive chitinase B (ChiB) from Serratia marcescens is partially closed, creating a tunnel-like catalytic cleft. To gain insight in the fundamental principles of substrate binding in this enzyme, we have studied the contribution of five key residues involved in substrate binding and tunnel formation to the thermodynamics of substrate binding. Mutation of Trp97, Phe190, Trp220 and Glu221, which are all part of the tunnel walls, resulted in significant less favorable conformational entropy change (ΔS°conf) upon binding (-TΔΔS°conf = ∼5 kcal/mol). This suggest that these residues are important for the structural rigidity and pre-shaping of the tunnel prior to binding. Mutation of Asp316, which, by forming a hydrogen bond to Trp97 is crucial in the active-site tunnel roof, resulted in a more favorable ΔS°conf relative to the wild type (-TΔΔS°conf = -2.2 kcal/mol). This shows that closing the tunnel-roof comes with an entropy cost, as previously suggested based on the crystal structures of GHs with tunnel topologies in complex with their substrates.
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Affiliation(s)
- Anne Grethe Hamre
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, N-1432 Ås, Norway
| | - Emil Ebbestad Frøberg
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, N-1432 Ås, Norway
| | - Vincent G H Eijsink
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, N-1432 Ås, Norway
| | - Morten Sørlie
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, N-1432 Ås, Norway.
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23
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Badino SF, Christensen SJ, Kari J, Windahl MS, Hvidt S, Borch K, Westh P. Exo-exo synergy between Cel6A and Cel7A fromHypocrea jecorina: Role of carbohydrate binding module and the endo-lytic character of the enzymes. Biotechnol Bioeng 2017; 114:1639-1647. [DOI: 10.1002/bit.26276] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/17/2017] [Accepted: 02/21/2017] [Indexed: 01/08/2023]
Affiliation(s)
- Silke F. Badino
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
| | - Stefan J. Christensen
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
| | - Jeppe Kari
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
| | - Michael S. Windahl
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
- Novozymes A/S; Bagsvaerd Denmark
| | - Søren Hvidt
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
| | | | - Peter Westh
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
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24
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Mayes HB, Knott BC, Crowley MF, Broadbelt LJ, Ståhlberg J, Beckham GT. Who's on base? Revealing the catalytic mechanism of inverting family 6 glycoside hydrolases. Chem Sci 2016; 7:5955-5968. [PMID: 30155195 PMCID: PMC6091422 DOI: 10.1039/c6sc00571c] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 05/29/2016] [Indexed: 12/16/2022] Open
Abstract
In several important classes of inverting carbohydrate-active enzymes, the identity of the catalytic base remains elusive, including in family 6 Glycoside Hydrolase (GH6) enzymes, which are key components of cellulase cocktails for cellulose depolymerization. Despite many structural and kinetic studies with both wild-type and mutant enzymes, especially on the Trichoderma reesei (Hypocrea jecorina) GH6 cellulase (TrCel6A), the catalytic base in the single displacement inverting mechanism has not been definitively identified in the GH6 family. Here, we employ transition path sampling to gain insight into the catalytic mechanism, which provides unbiased atomic-level understanding of key order parameters involved in cleaving the strong glycosidic bond. Our hybrid quantum mechanics and molecular mechanics (QM/MM) simulations reveal a network of hydrogen bonding that aligns two active site water molecules that play key roles in hydrolysis: one water molecule drives the reaction by nucleophilic attack on the substrate and a second shuttles a proton to the putative base (D175) via a short water wire. We also investigated the case where the putative base is mutated to an alanine, an enzyme that is experimentally still partially active. The simulations predict that proton hopping along a water wire via a Grotthuss mechanism provides a mechanism of catalytic rescue. Further simulations reveal that substrate processive motion is 'driven' by strong electrostatic interactions with the protein at the product sites and that the -1 sugar adopts a 2SO ring configuration as it reaches its binding site. This work thus elucidates previously elusive steps in the processive catalytic mechanism of this important class of enzymes.
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Affiliation(s)
- Heather B Mayes
- Department of Chemical and Biological Engineering , Northwestern University , Evanston , IL 60208 , USA
- National Bioenergy Center , National Renewable Energy Laboratory , Golden , CO 80401 , USA .
| | - Brandon C Knott
- National Bioenergy Center , National Renewable Energy Laboratory , Golden , CO 80401 , USA .
| | - Michael F Crowley
- Biosciences Center , National Renewable Energy Laboratory , Golden , CO 80401 , USA
| | - Linda J Broadbelt
- Department of Chemical and Biological Engineering , Northwestern University , Evanston , IL 60208 , USA
| | - Jerry Ståhlberg
- Department of Chemistry and Biotechnology , Swedish University of Agricultural Sciences , SE-75007 , Uppsala , Sweden .
| | - Gregg T Beckham
- National Bioenergy Center , National Renewable Energy Laboratory , Golden , CO 80401 , USA .
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25
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Qian M, Guan S, Shan Y, Zhang H, Wang S. Structural and molecular basis of cellulase Cel48F by computational modeling: Insight into catalytic and product release mechanism. J Struct Biol 2016; 194:347-56. [DOI: 10.1016/j.jsb.2016.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/04/2016] [Accepted: 03/14/2016] [Indexed: 11/26/2022]
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26
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Yenenler A, Sezerman OU. Design and characterizations of two novel cellulases through single-gene shuffling of Cel12A (EG3) gene fromTrichoderma reseei. Protein Eng Des Sel 2016; 29:219-229. [DOI: 10.1093/protein/gzw011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 03/24/2016] [Indexed: 11/14/2022] Open
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27
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Jana S, Hamre AG, Wildberger P, Holen MM, Eijsink VGH, Beckham GT, Sørlie M, Payne CM. Aromatic-Mediated Carbohydrate Recognition in Processive Serratia marcescens Chitinases. J Phys Chem B 2016; 120:1236-49. [PMID: 26824449 DOI: 10.1021/acs.jpcb.5b12610] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microorganisms use a host of enzymes, including processive glycoside hydrolases, to deconstruct recalcitrant polysaccharides to sugars. Processive glycoside hydrolases closely associate with polymer chains and repeatedly cleave glycosidic linkages without dissociating from the crystalline surface after each hydrolytic step; they are typically the most abundant enzymes in both natural secretomes and industrial cocktails by virtue of their significant hydrolytic potential. The ubiquity of aromatic residues lining the enzyme catalytic tunnels and clefts is a notable feature of processive glycoside hydrolases. We hypothesized that these aromatic residues have uniquely defined roles, such as substrate chain acquisition and binding in the catalytic tunnel, that are defined by their local environment and position relative to the substrate and the catalytic center. Here, we investigated this hypothesis with variants of Serratia marcescens family 18 processive chitinases ChiA and ChiB. We applied molecular simulation and free energy calculations to assess active site dynamics and ligand binding free energies. Isothermal titration calorimetry provided further insight into enthalpic and entropic contributions to ligand binding free energy. Thus, the roles of six aromatic residues, Trp-167, Trp-275, and Phe-396 in ChiA, and Trp-97, Trp-220, and Phe-190 in ChiB, have been examined. We observed that point mutation of the tryptophan residues to alanine results in unfavorable changes in the free energy of binding relative to wild-type. The most drastic effects were observed for residues positioned at the "entrances" of the deep substrate-binding clefts and known to be important for processivity. Interestingly, phenylalanine mutations in ChiA and ChiB had little to no effect on chito-oligomer binding, in accordance with the limited effects of their removal on chitinase functionality.
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Affiliation(s)
- Suvamay Jana
- Department of Chemical and Materials Engineering, University of Kentucky , Lexington, Kentucky 40506-0046, United States
| | - Anne Grethe Hamre
- Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences , Ås 1430, Norway
| | - Patricia Wildberger
- Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences , Ås 1430, Norway
| | - Matilde Mengkrog Holen
- Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences , Ås 1430, Norway
| | - Vincent G H Eijsink
- Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences , Ås 1430, Norway
| | - Gregg T Beckham
- National Bioenergy Center, National Renewable Energy Laboratory , Golden, Colorado 80401, United States
| | - Morten Sørlie
- Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences , Ås 1430, Norway
| | - Christina M Payne
- Department of Chemical and Materials Engineering, University of Kentucky , Lexington, Kentucky 40506-0046, United States
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Simulation studies of substrate recognition by the exocellulase CelF from
Clostridium cellulolyticum. Biotechnol Bioeng 2016; 113:1433-40. [DOI: 10.1002/bit.25909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 12/07/2015] [Accepted: 12/18/2015] [Indexed: 11/07/2022]
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Hamid SBA, Islam MM, Das R. Cellulase biocatalysis: key influencing factors and mode of action. CELLULOSE 2015; 22:2157-2182. [DOI: 10.1007/s10570-015-0672-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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30
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Abstract
SUMMARY Biomass is constructed of dense recalcitrant polymeric materials: proteins, lignin, and holocellulose, a fraction constituting fibrous cellulose wrapped in hemicellulose-pectin. Bacteria and fungi are abundant in soil and forest floors, actively recycling biomass mainly by extracting sugars from holocellulose degradation. Here we review the genome-wide contents of seven Aspergillus species and unravel hundreds of gene models encoding holocellulose-degrading enzymes. Numerous apparent gene duplications followed functional evolution, grouping similar genes into smaller coherent functional families according to specialized structural features, domain organization, biochemical activity, and genus genome distribution. Aspergilli contain about 37 cellulase gene models, clustered in two mechanistic categories: 27 hydrolyze and 10 oxidize glycosidic bonds. Within the oxidative enzymes, we found two cellobiose dehydrogenases that produce oxygen radicals utilized by eight lytic polysaccharide monooxygenases that oxidize glycosidic linkages, breaking crystalline cellulose chains and making them accessible to hydrolytic enzymes. Among the hydrolases, six cellobiohydrolases with a tunnel-like structural fold embrace single crystalline cellulose chains and cooperate at nonreducing or reducing end termini, splitting off cellobiose. Five endoglucanases group into four structural families and interact randomly and internally with cellulose through an open cleft catalytic domain, and finally, seven extracellular β-glucosidases cleave cellobiose and related oligomers into glucose. Aspergilli contain, on average, 30 hemicellulase and 7 accessory gene models, distributed among 9 distinct functional categories: the backbone-attacking enzymes xylanase, mannosidase, arabinase, and xyloglucanase, the short-side-chain-removing enzymes xylan α-1,2-glucuronidase, arabinofuranosidase, and xylosidase, and the accessory enzymes acetyl xylan and feruloyl esterases.
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31
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Ardèvol A, Rovira C. Reaction Mechanisms in Carbohydrate-Active Enzymes: Glycoside Hydrolases and Glycosyltransferases. Insights from ab Initio Quantum Mechanics/Molecular Mechanics Dynamic Simulations. J Am Chem Soc 2015; 137:7528-47. [DOI: 10.1021/jacs.5b01156] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Albert Ardèvol
- Departament
de Química Orgànica and Institut de Química Teòrica
i Computacional (IQTCUB), Universitat de Barcelona, Martí
i Franquès 1, 08028 Barcelona, Spain
| | - Carme Rovira
- Departament
de Química 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, 08018 Barcelona, Spain
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Quantifying bond distortions in transient enzyme species by a combination of density functional theory calculations and time-resolved infrared difference spectroscopy. Implications for the mechanism of dephosphorylation of the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA1a). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1036-43. [PMID: 25986318 DOI: 10.1016/j.bbabio.2015.05.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/22/2015] [Accepted: 05/09/2015] [Indexed: 12/26/2022]
Abstract
The sarcoplasmic Ca(2+)-ATPase (SERCA1a) forms two phosphoenzyme intermediates during Ca(2+) pumping. The second intermediate E2P hydrolyzes rapidly, which is essential for the rapid removal of Ca(2+) from the cytosol of muscle cells. The present work studies whether a weakening of the scissile PO bond in the E2P ground state facilitates dephosphorylation. To this end, the experimentally known vibrational spectrum of the E2P phosphate group was calculated with density functional theory (DFT) using structural models at two levels of structural complexity: (i) Models of acetyl phosphate in simple environments and (ii) ~150 atom models of the catalytic site. It was found that the enzyme environment distorts the structure of the phosphate group: one of the terminal PO bonds is shorter in the catalytic site indicating weaker interactions than in water. However, the bond that bridges phosphate and Asp351 is unaffected. This indicates that the scissile PO bond is not weakened by the enzyme environment of E2P. A second finding was that the catalytic site of the E2P state in aqueous solution appears to adopt a structure as in the crystals with BeF3(-), where the ATPase is in a non-reactive conformation. The reactant state of the dephosphorylation reaction differs from the E2P ground state: Glu183 faces Asp351 and positions the attacking water molecule. This state has a 0.04Å longer, and thus weaker, bridging PO bond. The reactant state is not detected in our experiments, indicating that its energy is at least 1kcal/mol higher than that of the E2P ground state.
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Vermaas JV, Crowley MF, Beckham GT, Payne CM. Effects of lytic polysaccharide monooxygenase oxidation on cellulose structure and binding of oxidized cellulose oligomers to cellulases. J Phys Chem B 2015; 119:6129-43. [PMID: 25785779 DOI: 10.1021/acs.jpcb.5b00778] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In nature, polysaccharide glycosidic bonds are cleaved by hydrolytic enzymes for a vast array of biological functions. Recently, a new class of enzymes that utilize an oxidative mechanism to cleave glycosidic linkages was discovered; these enzymes are called lytic polysaccharide monooxygenases (LPMO). These oxidative enzymes are synergistic with cocktails of hydrolytic enzymes and are thought to act primarily on crystalline regions, in turn providing new sites of productive attachment and detachment for processive hydrolytic enzymes. In the case of cellulose, the homopolymer of β-1,4-d-glucose, enzymatic oxidation occurs at either the reducing end or the nonreducing end of glucose, depending on enzymatic specificity, and results in the generation of oxidized chemical substituents at polymer chain ends. LPMO oxidation of cellulose is thought to produce either a lactone at the reducing end of glucose that can spontaneously or enzymatically convert to aldonic acid or 4-keto-aldose at the nonreducing end that may further oxidize to a geminal diol. Here, we use molecular simulation to examine the effect of oxidation on the structure of crystalline cellulose. The simulations highlight variations in behaviors depending on the chemical identity of the oxidized species and its location within the cellulose fibril, as different oxidized species introduce steric effects that disrupt local crystallinity and in some cases reduce the work needed for polymer decrystallization. Reducing-end oxidations are easiest to decrystallize when located at the end of the fibril, whereas nonreducing end oxidations readily decrystallize from internal cleavage sites despite their lower solvent accessibility. The differential in decrystallization free energy suggests a molecular mechanism consistent with experimentally observed LPMO/cellobiohydrolase synergy. Additionally, the soluble oxidized cellobiose products released by hydrolytic cellulases may bind to the active sites of cellulases with different affinities relative to cellobiose itself, which potentially affects hydrolytic turnover through product inhibition. To examine the effect of oxidation on cello-oligomer binding, we use thermodynamic integration to compute the relative change in binding free energy between the hydrolyzed and oxidized products in the active site of Family 7 and Family 6 processive glycoside hydrolases, Trichoderma reesei Cel7A and Cel6A, which are key industrial cellulases and commonly used model systems for fungal cellulases. Our results suggest that the equilibrium between the two reducing end oxidized products, favoring the linear aldonic acid, may increase product inhibition, which would in turn reduce processive substrate turnover. In the case of LMPO action at the nonreducing end, oxidation appears to lower affinity with the nonreducing end specific cellulase, reducing product inhibition and potentially promoting processive cellulose turnover. Overall, this suggests that oxidation of recalcitrant polysaccharides by LPMOs accelerates degradation not only by increasing the concentration of chain termini but also by reducing decrystallization work, and that product inhibition may be somewhat reduced as a result.
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Affiliation(s)
- Josh V Vermaas
- †Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,‡National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Michael F Crowley
- §Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Gregg T Beckham
- ‡National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Christina M Payne
- ∥Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky 40506, United States.,⊥Center for Computational Science, University of Kentucky, Lexington, Kentucky 40506, United States
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34
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Payne CM, Knott BC, Mayes HB, Hansson H, Himmel ME, Sandgren M, Ståhlberg J, Beckham GT. Fungal Cellulases. Chem Rev 2015; 115:1308-448. [DOI: 10.1021/cr500351c] [Citation(s) in RCA: 533] [Impact Index Per Article: 59.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Christina M. Payne
- Department
of Chemical and Materials Engineering and Center for Computational
Sciences, University of Kentucky, 177 F. Paul Anderson Tower, Lexington, Kentucky 40506, United States
| | - Brandon C. Knott
- National
Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
| | - Heather B. Mayes
- Department
of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Henrik Hansson
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Michael E. Himmel
- Biosciences
Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Mats Sandgren
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Jerry Ståhlberg
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Gregg T. Beckham
- National
Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
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35
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Schutt TC, Bharadwaj VS, Granum DM, Maupin CM. The impact of active site protonation on substrate ring conformation in Melanocarpus albomyces cellobiohydrolase Cel7B. Phys Chem Chem Phys 2015; 17:16947-58. [DOI: 10.1039/c5cp01801c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding how the protonation state of active site residues impacts the enzyme's structure and substrate conformation is important for improving the efficiency and economic viability of the degradation of cellulosic materials as feedstock for liquid fuel and value-added chemicals.
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Affiliation(s)
- Timothy C. Schutt
- Chemical and Biological Engineering Department
- Colorado School of Mines
- Golden
- USA
| | - Vivek S. Bharadwaj
- Chemical and Biological Engineering Department
- Colorado School of Mines
- Golden
- USA
| | - David M. Granum
- Chemical and Biological Engineering Department
- Colorado School of Mines
- Golden
- USA
| | - C. Mark Maupin
- Chemical and Biological Engineering Department
- Colorado School of Mines
- Golden
- USA
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36
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Yang D, Parlange JY, Walker LP. Cellulases Significantly Alter the Nano-Scale Reaction Space for Pretreated Lignocellulosic Biomass. Ind Biotechnol (New Rochelle N Y) 2014. [DOI: 10.1089/ind.2014.0028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Dong Yang
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY
| | - Jean-Yves Parlange
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY
| | - Larry P. Walker
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY
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37
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Shang BZ, Chu JW. Kinetic Modeling at Single-Molecule Resolution Elucidates the Mechanisms of Cellulase Synergy. ACS Catal 2014. [DOI: 10.1021/cs500126q] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Barry Z. Shang
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
| | - Jhih-Wei Chu
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
- Department
of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, ROC
- Institute
of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu, Taiwan, ROC
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38
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Igarashi K, Uchihashi T, Uchiyama T, Sugimoto H, Wada M, Suzuki K, Sakuda S, Ando T, Watanabe T, Samejima M. Two-way traffic of glycoside hydrolase family 18 processive chitinases on crystalline chitin. Nat Commun 2014; 5:3975. [DOI: 10.1038/ncomms4975] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 04/25/2014] [Indexed: 11/09/2022] Open
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39
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Towards a molecular-level theory of carbohydrate processivity in glycoside hydrolases. Curr Opin Biotechnol 2014; 27:96-106. [DOI: 10.1016/j.copbio.2013.12.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 12/04/2013] [Indexed: 10/25/2022]
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40
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Granum DM, Schutt TC, Maupin CM. Computational Evaluation of the Dynamic Fluctuations of Peripheral Loops Enclosing the Catalytic Tunnel of a Family 7 Cellobiohydrolase. J Phys Chem B 2014; 118:5340-9. [DOI: 10.1021/jp5011555] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David M. Granum
- Chemical
and Biological Engineering
Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - Timothy C. Schutt
- Chemical
and Biological Engineering
Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - C. Mark Maupin
- Chemical
and Biological Engineering
Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
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41
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Mercadante D, Melton LD, Jameson GB, Williams MAK. Processive pectin methylesterases: the role of electrostatic potential, breathing motions and bond cleavage in the rectification of Brownian motions. PLoS One 2014; 9:e87581. [PMID: 24503943 PMCID: PMC3913658 DOI: 10.1371/journal.pone.0087581] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 12/23/2013] [Indexed: 12/26/2022] Open
Abstract
Pectin methylesterases (PMEs) hydrolyze the methylester groups that are found on the homogalacturonan (HG) chains of pectic polysaccharides in the plant cell wall. Plant and bacterial PMEs are especially interesting as the resulting de-methylesterified (carboxylated) sugar residues are found to be arranged contiguously, indicating a so-called processive nature of these enzymes. Here we report the results of continuum electrostatics calculations performed along the molecular dynamics trajectory of a PME-HG-decasaccharide complex. In particular it was observed that, when the methylester groups of the decasaccharide were arranged in order to mimic the just-formed carboxylate product of de-methylesterification, a net unidirectional sliding of the model decasaccharide was subsequently observed along the enzyme’s binding groove. The changes that occurred in the electrostatic binding energy and protein dynamics during this translocation provide insights into the mechanism by which the enzyme rectifies Brownian motions to achieve processivity. The free energy that drives these molecular motors is thus demonstrated to be incorporated endogenously in the methylesterified groups of the HG chains and is not supplied exogenously.
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Affiliation(s)
- Davide Mercadante
- The Riddet Institute, Palmerston North, New Zealand
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | - Laurence D. Melton
- The Riddet Institute, Palmerston North, New Zealand
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | - Geoffrey B. Jameson
- The Riddet Institute, Palmerston North, New Zealand
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University, Wellington, New Zealand
| | - Martin A. K. Williams
- The Riddet Institute, Palmerston North, New Zealand
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University, Wellington, New Zealand
- * E-mail:
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42
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Itoh T. Design of Ionic Liquids for Cellulose Dissolution. PRODUCTION OF BIOFUELS AND CHEMICALS WITH IONIC LIQUIDS 2014. [DOI: 10.1007/978-94-007-7711-8_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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43
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V. Sambasivarao S, M. Granum D, Wang H, Mark Maupin C. Identifying the Enzymatic Mode of Action for Cellulase Enzymes by Means of Docking Calculations and a Machine Learning Algorithm. AIMS MOLECULAR SCIENCE 2014. [DOI: 10.3934/molsci.2014.1.59] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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44
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Lu T, Zhang Z, Zhang C. Glycosyl rotation and distortion by key residues in Endocellulase Cel6A from Theromobifida fusca. Glycobiology 2013; 24:247-51. [PMID: 24287179 DOI: 10.1093/glycob/cwt105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Endocellulases are one kind of the important biodegrading cellulose enzymes. Experimental results show that a rotated and distorted preactivated structure exists before the substrate entering the transition state. The molecular dynamic simulation of endocellulase Cel6A models revealed a correlation between the rotation and distortion of pyranoside ring in -1 glycosyl unit of the substrate. The two key residues, Tyr73 and Ser189, in Cal6A cooperate to rotate and distort the pyranoside ring in the cellulose hydrolysis.
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Affiliation(s)
- Tao Lu
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
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45
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Wu M, Bu L, Vuong TV, Wilson DB, Crowley MF, Sandgren M, Ståhlberg J, Beckham GT, Hansson H. Loop motions important to product expulsion in the Thermobifida fusca glycoside hydrolase family 6 cellobiohydrolase from structural and computational studies. J Biol Chem 2013; 288:33107-17. [PMID: 24085303 DOI: 10.1074/jbc.m113.502765] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cellobiohydrolases (CBHs) are typically major components of natural enzyme cocktails for biomass degradation. Their active sites are enclosed in a tunnel, enabling processive hydrolysis of cellulose chains. Glycoside hydrolase Family 6 (GH6) CBHs act from nonreducing ends by an inverting mechanism and are present in many cellulolytic fungi and bacteria. The bacterial Thermobifida fusca Cel6B (TfuCel6B) exhibits a longer and more enclosed active site tunnel than its fungal counterparts. Here, we determine the structures of two TfuCel6B mutants co-crystallized with cellobiose, D274A (catalytic acid), and the double mutant D226A/S232A, which targets the putative catalytic base and a conserved serine that binds the nucleophilic water. The ligand binding and the structure of the active site are retained when compared with the wild type structure, supporting the hypothesis that these residues are directly involved in catalysis. One structure exhibits crystallographic waters that enable construction of a model of the α-anomer product after hydrolysis. Interestingly, the product sites of TfuCel6B are completely enclosed by an "exit loop" not present in fungal GH6 CBHs and by an extended "bottom loop". From the structures, we hypothesize that either of the loops enclosing the product subsites in the TfuCel6B active site tunnel must open substantially for product release. With simulation, we demonstrate that both loops can readily open to allow product release with equal probability in solution or when the enzyme is engaged on cellulose. Overall, this study reveals new structural details of GH6 CBHs likely important for functional differences among enzymes from this important family.
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Affiliation(s)
- Miao Wu
- From the Department of Molecular Biology, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
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46
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Payne CM, Resch MG, Chen L, Crowley MF, Himmel ME, Taylor LE, Sandgren M, Ståhlberg J, Stals I, Tan Z, Beckham GT. Glycosylated linkers in multimodular lignocellulose-degrading enzymes dynamically bind to cellulose. Proc Natl Acad Sci U S A 2013; 110:14646-51. [PMID: 23959893 PMCID: PMC3767562 DOI: 10.1073/pnas.1309106110] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Plant cell-wall polysaccharides represent a vast source of food in nature. To depolymerize polysaccharides to soluble sugars, many organisms use multifunctional enzyme mixtures consisting of glycoside hydrolases, lytic polysaccharide mono-oxygenases, polysaccharide lyases, and carbohydrate esterases, as well as accessory, redox-active enzymes for lignin depolymerization. Many of these enzymes that degrade lignocellulose are multimodular with carbohydrate-binding modules (CBMs) and catalytic domains connected by flexible, glycosylated linkers. These linkers have long been thought to simply serve as a tether between structured domains or to act in an inchworm-like fashion during catalytic action. To examine linker function, we performed molecular dynamics (MD) simulations of the Trichoderma reesei Family 6 and Family 7 cellobiohydrolases (TrCel6A and TrCel7A, respectively) bound to cellulose. During these simulations, the glycosylated linkers bind directly to cellulose, suggesting a previously unknown role in enzyme action. The prediction from the MD simulations was examined experimentally by measuring the binding affinity of the Cel7A CBM and the natively glycosylated Cel7A CBM-linker. On crystalline cellulose, the glycosylated linker enhances the binding affinity over the CBM alone by an order of magnitude. The MD simulations before and after binding of the linker also suggest that the bound linker may affect enzyme action due to significant damping in the enzyme fluctuations. Together, these results suggest that glycosylated linkers in carbohydrate-active enzymes, which are intrinsically disordered proteins in solution, aid in dynamic binding during the enzymatic deconstruction of plant cell walls.
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Affiliation(s)
- Christina M. Payne
- Biosciences Center and
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506
| | | | - Liqun Chen
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, CO 80303
| | | | | | | | - Mats Sandgren
- Department of Molecular Biology, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - Jerry Ståhlberg
- Department of Molecular Biology, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - Ingeborg Stals
- Faculty of Applied Bioscience Engineering, University College Ghent, 9000 Ghent, Belgium
- Department of Biochemistry and Molecular Biology, Ghent University, 9000 Ghent, Belgium; and
| | - Zhongping Tan
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, CO 80303
| | - Gregg T. Beckham
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401
- Department of Chemical Engineering, Colorado School of Mines, Golden, CO 80401
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47
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Insights into exo- and endoglucanase activities of family 6 glycoside hydrolases from Podospora anserina. Appl Environ Microbiol 2013; 79:4220-9. [PMID: 23645193 DOI: 10.1128/aem.00327-13] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The ascomycete Podospora anserina is a coprophilous fungus that grows at late stages on droppings of herbivores. Its genome encodes a large diversity of carbohydrate-active enzymes. Among them, four genes encode glycoside hydrolases from family 6 (GH6), the members of which comprise putative endoglucanases and exoglucanases, some of them exerting important functions for biomass degradation in fungi. Therefore, this family was selected for functional analysis. Three of the enzymes, P. anserina Cel6A (PaCel6A), PaCel6B, and PaCel6C, were functionally expressed in the yeast Pichia pastoris. All three GH6 enzymes hydrolyzed crystalline and amorphous cellulose but were inactive on hydroxyethyl cellulose, mannan, galactomannan, xyloglucan, arabinoxylan, arabinan, xylan, and pectin. PaCel6A had a catalytic efficiency on cellotetraose comparable to that of Trichoderma reesei Cel6A (TrCel6A), but PaCel6B and PaCel6C were clearly less efficient. PaCel6A was the enzyme with the highest stability at 45°C, while PaCel6C was the least stable enzyme, losing more than 50% of its activity after incubation at temperatures above 30°C for 24 h. In contrast to TrCel6A, all three studied P. anserina GH6 cellulases were stable over a wide range of pHs and conserved high activity at pH values of up to 9. Each enzyme displayed a distinct substrate and product profile, highlighting different modes of action, with PaCel6A being the enzyme most similar to TrCel6A. PaCel6B was the only enzyme with higher specific activity on carboxymethylcellulose (CMC) than on Avicel and showed lower processivity than the others. Structural modeling predicts an open catalytic cleft, suggesting that PaCel6B is an endoglucanase.
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48
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Bu L, Crowley MF, Himmel ME, Beckham GT. Computational investigation of the pH dependence of loop flexibility and catalytic function in glycoside hydrolases. J Biol Chem 2013; 288:12175-86. [PMID: 23504310 DOI: 10.1074/jbc.m113.462465] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cellulase enzymes cleave glycosidic bonds in cellulose to produce cellobiose via either retaining or inverting hydrolysis mechanisms, which are significantly pH-dependent. Many fungal cellulases function optimally at pH ~5, and their activities decrease dramatically at higher or lower pH. To understand the molecular-level implications of pH in cellulase structure, we use a hybrid, solvent-based, constant pH molecular dynamics method combined with pH-based replica exchange to determine the pK(a) values of titratable residues of a glycoside hydrolase (GH) family 6 cellobiohydrolase (Cel6A) and a GH family 7 cellobiohydrolase (Cel7A) from the fungus Hypocrea jecorina. For both enzymes, we demonstrate that a bound substrate significantly affects the pKa values of the acid residues at the catalytic center. The calculated pK(a) values of catalytic residues confirm their proposed roles from structural studies and are consistent with the experimentally measured apparent pKa values. Additionally, GHs are known to impart a strained pucker conformation in carbohydrate substrates in active sites for catalysis, and results from free energy calculations combined with constant pH molecular dynamics suggest that the correct ring pucker is stable near the optimal pH for both Cel6A and Cel7A. Much longer molecular dynamics simulations of Cel6A and Cel7A with fixed protonation states based on the calculated pK(a) values suggest that pH affects the flexibility of tunnel loops, which likely affects processivity and substrate complexation. Taken together, this work demonstrates several molecular-level effects of pH on GH enzymes important for cellulose turnover in the biosphere and relevant to biomass conversion processes.
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Affiliation(s)
- Lintao Bu
- National Bioenergy Center, Colorado School of Mines, Golden, Colorado 80401, USA.
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Sandgren M, Wu M, Karkehabadi S, Mitchinson C, Kelemen BR, Larenas EA, Ståhlberg J, Hansson H. The Structure of a Bacterial Cellobiohydrolase: The Catalytic Core of the Thermobifida fusca Family GH6 Cellobiohydrolase Cel6B. J Mol Biol 2013; 425:622-35. [DOI: 10.1016/j.jmb.2012.11.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 11/26/2012] [Accepted: 11/28/2012] [Indexed: 10/27/2022]
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den Haan R, Kroukamp H, van Zyl JHD, van Zyl WH. Cellobiohydrolase secretion by yeast: Current state and prospects for improvement. Process Biochem 2013. [DOI: 10.1016/j.procbio.2012.11.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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