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Garg P, Manoj N. Structure of an iminosugar complex of a glycoside hydrolase family 5 lichenase provides insights into the active site. Biochimie 2023; 204:69-77. [PMID: 36084911 DOI: 10.1016/j.biochi.2022.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 05/23/2022] [Accepted: 09/01/2022] [Indexed: 01/12/2023]
Abstract
TmCel5B is a lichenase belonging to glycoside hydrolase family 5 subfamily 36 (GH5_36). To gain insights into the active site of this subfamily which contains multifunctional endoglycanases, we determined the crystal structure of TmCel5B in complex with an iminosugar, 1-deoxynojiromycin (DNJ). DNJ is bound to the -1 subsite, making a network of non-covalent interactions with the acid/base residue Glu139, the nucleophile Glu259, and with other residues that are conserved across the GH5 family. The catalytic site displayed a Glu-Arg-Glu triad of the catalytic glutamates that is unique to the GH5_36 subfamily. Structural comparison of active sites of GH5_36 homologs revealed divergent residues and loop regions that are likely molecular determinants of homolog-specific properties. Furthermore, a comparative analysis of the binding modes of iminocyclitol complexes of GH5 homologs revealed the structural basis of their binding to GH5 glycosidases, in which the subsite binding location, the interactions of the ligand with specific conserved residues, and the electrostatic interactions of the catalytic glutamates with the ring nitrogen, are crucial.
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Affiliation(s)
- Puneet Garg
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Narayanan Manoj
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, India.
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Martins MP, Morais MAB, Persinoti GF, Galinari RH, Yu L, Yoshimi Y, Passos Nunes FB, Lima TB, Barbieri SF, Silveira JLM, Lombard V, Terrapon N, Dupree P, Henrissat B, Murakami MT. Glycoside hydrolase subfamily GH5_57 features a highly redesigned catalytic interface to process complex hetero-β-mannans. ACTA CRYSTALLOGRAPHICA SECTION D STRUCTURAL BIOLOGY 2022; 78:1358-1372. [DOI: 10.1107/s2059798322009561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 09/28/2022] [Indexed: 11/05/2022]
Abstract
Glycoside hydrolase family 5 (GH5) harbors diverse substrate specificities and modes of action, exhibiting notable molecular adaptations to cope with the stereochemical complexity imposed by glycosides and carbohydrates such as cellulose, xyloglucan, mixed-linkage β-glucan, laminarin, (hetero)xylan, (hetero)mannan, galactan, chitosan, N-glycan, rutin and hesperidin. GH5 has been divided into subfamilies, many with higher functional specificity, several of which have not been characterized to date and some that have yet to be discovered with the exploration of sequence/taxonomic diversity. In this work, the current GH5 subfamily inventory is expanded with the discovery of the GH5_57 subfamily by describing an endo-β-mannanase (CapGH5_57) from an uncultured Bacteroidales bacterium recovered from the capybara gut microbiota. Biochemical characterization showed that CapGH5_57 is active on glucomannan, releasing oligosaccharides with a degree of polymerization from 2 to 6, indicating it to be an endo-β-mannanase. The crystal structure, which was solved using single-wavelength anomalous diffraction, revealed a massively redesigned catalytic interface compared with GH5 mannanases. The typical aromatic platforms and the characteristic α-helix-containing β6–α6 loop in the positive-subsite region of GH5_7 mannanases are absent in CapGH5_57, generating a large and open catalytic interface that might favor the binding of branched substrates. Supporting this, CapGH5_57 contains a tryptophan residue adjacent and perpendicular to the cleavage site, indicative of an anchoring site for a substrate with a substitution at the −1 glycosyl moiety. Taken together, these results suggest that despite presenting endo activity on glucomannan, CapGH5_57 may have a new type of substituted heteromannan as its natural substrate. This work demonstrates the still great potential for discoveries regarding the mechanistic and functional diversity of this large and polyspecific GH family by unveiling a novel catalytic interface sculpted to recognize complex heteromannans, which led to the establishment of the GH5_57 subfamily.
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Cann I, Pereira GV, Abdel-Hamid AM, Kim H, Wefers D, Kayang BB, Kanai T, Sato T, Bernardi RC, Atomi H, Mackie RI. Thermophilic Degradation of Hemicellulose, a Critical Feedstock in the Production of Bioenergy and Other Value-Added Products. Appl Environ Microbiol 2020; 86:e02296-19. [PMID: 31980431 PMCID: PMC7082577 DOI: 10.1128/aem.02296-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Renewable fuels have gained importance as the world moves toward diversifying its energy portfolio. A critical step in the biomass-to-bioenergy initiative is deconstruction of plant cell wall polysaccharides to their unit sugars for subsequent fermentation to fuels. To acquire carbon and energy for their metabolic processes, diverse microorganisms have evolved genes encoding enzymes that depolymerize polysaccharides to their carbon/energy-rich building blocks. The microbial enzymes mostly target the energy present in cellulose, hemicellulose, and pectin, three major forms of energy storage in plants. In the effort to develop bioenergy as an alternative to fossil fuel, a common strategy is to harness microbial enzymes to hydrolyze cellulose to glucose for fermentation to fuels. However, the conversion of plant biomass to renewable fuels will require both cellulose and hemicellulose, the two largest components of the plant cell wall, as feedstock to improve economic feasibility. Here, we explore the enzymes and strategies evolved by two well-studied bacteria to depolymerize the hemicelluloses xylan/arabinoxylan and mannan. The sets of enzymes, in addition to their applications in biofuels and value-added chemical production, have utility in animal feed enzymes, a rapidly developing industry with potential to minimize adverse impacts of animal agriculture on the environment.
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Affiliation(s)
- Isaac Cann
- Department of Animal Science, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto, Japan
| | - Gabriel V Pereira
- Department of Animal Science, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Ahmed M Abdel-Hamid
- Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Heejin Kim
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Daniel Wefers
- Karlsruhe Institute of Technology, Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Karlsruhe, Germany
| | - Boniface B Kayang
- Department of Animal Science, School of Agriculture, University of Ghana, Legon, Ghana
| | - Tamotsu Kanai
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto, Japan
| | - Takaaki Sato
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto, Japan
- JST, CREST, Tokyo, Japan
| | - Rafael C Bernardi
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Haruyuki Atomi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto, Japan
- JST, CREST, Tokyo, Japan
| | - Roderick I Mackie
- Department of Animal Science, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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Identification of the nucleophile catalytic residue of GH51 α-L-arabinofuranosidase from Pleurotus ostreatus. AMB Express 2015; 5:79. [PMID: 26690659 PMCID: PMC4686458 DOI: 10.1186/s13568-015-0164-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 11/12/2015] [Indexed: 11/21/2022] Open
Abstract
In this study, the recombinant α-l-arabinofuranosidase from the fungus Pleurotus ostreatus (rPoAbf) was subjected to site-directed mutagenesis in order to identify the catalytic nucleophile residue. Based on bioinformatics and homology modelling analyses, E449 was revealed to be the potential nucleophilic residue. Thus, the mutant E449G of PoAbf was recombinantly expressed in Pichia pastoris and its recombinant expression level and reactivity were investigated in comparison to the wild-type. The design of a suitable set of hydrolysis experiments in the presence or absence of alcoholic arabinosyl acceptors and/or formate salts allowed to unambiguously identify the residue E449 as the nucleophile residue involved in the retaining mechanism of this GH51 arabinofuranosidase. 1H NMR analysis was applied for the identification of the products and the assignement of their anomeric configuration.
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Structural Insight of a Trimodular Halophilic Cellulase with a Family 46 Carbohydrate-Binding Module. PLoS One 2015; 10:e0142107. [PMID: 26562160 PMCID: PMC4643050 DOI: 10.1371/journal.pone.0142107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 10/16/2015] [Indexed: 01/08/2023] Open
Abstract
Cellulases are the key enzymes used in the biofuel industry. A typical cellulase contains a catalytic domain connected to a carbohydrate-binding module (CBM) through a flexible linker. Here we report the structure of an atypical trimodular cellulase which harbors a catalytic domain, a CBM46 domain and a rigid CBM_X domain between them. The catalytic domain shows the features of GH5 family, while the CBM46 domain has a sandwich-like structure. The catalytic domain and the CBM46 domain form an extended substrate binding cleft, within which several tryptophan residues are well exposed. Mutagenesis assays indicate that these residues are essential for the enzymatic activities. Gel affinity electrophoresis shows that these tryptophan residues are involved in the polysaccharide substrate binding. Also, electrostatic potential analysis indicates that almost the entire solvent accessible surface of CelB is negatively charged, which is consistent with the halophilic nature of this enzyme.
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Poma AB, Chwastyk M, Cieplak M. Polysaccharide-Protein Complexes in a Coarse-Grained Model. J Phys Chem B 2015; 119:12028-41. [PMID: 26291477 DOI: 10.1021/acs.jpcb.5b06141] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We construct two variants of coarse-grained models of three hexaoses: one based on the centers of mass of the monomers and the other associated with the C4 atoms. The latter is found to be better defined and more suitable for studying interactions with proteins described within α-C based models. We determine the corresponding effective stiffness constants through all-atom simulations and two statistical methods. One method is the Boltzmann inversion (BI) and the other, named energy-based (EB), involves direct monitoring of energies as a function of the variables that define the stiffness potentials. The two methods are generally consistent in their account of the stiffness. We find that the elastic constants differ between the hexaoses and are noticeably different from those determined for the crystalline cellulose Iβ. The nonbonded couplings through hydrogen bonds between different sugar molecules are modeled by the Lennard-Jones potentials and are found to be stronger than the hydrogen bonds in proteins. We observe that the EB method agrees with other theoretical and experimental determinations of the nonbonded parameters much better than BI. We then consider the hexaose-Man5B catalytic complexes and determine the contact energies between their the C4-α-C atoms. These interactions are found to be stronger than the proteinic hydrogen bonds: about four times as strong for cellohexaose and two times for mannohexaose. The fluctuational dynamics of the coarse-grained complexes are found to be compatible with previous all-atom studies by Bernardi et al.
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Affiliation(s)
- Adolfo B Poma
- Institute of Physics, Polish Academy of Sciences , Aleja Lotników 32/46, 02-668 Warsaw, Poland
| | - Mateusz Chwastyk
- Institute of Physics, Polish Academy of Sciences , Aleja Lotników 32/46, 02-668 Warsaw, Poland
| | - Marek Cieplak
- Institute of Physics, Polish Academy of Sciences , Aleja Lotników 32/46, 02-668 Warsaw, Poland
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Zhang Y, Zhao Z, Liu H. Deriving Chemically Essential Interactions Based on Active Site Alignments and Quantum Chemical Calculations: A Case Study on Glycoside Hydrolases. ACS Catal 2015. [DOI: 10.1021/cs501709d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yinliang Zhang
- School
of Life Sciences, University of Science and Technology of China, 443 Huangshan Road, Hefei, Anhui 230027, China
| | - Zheng Zhao
- Hefei
Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Haiyan Liu
- School
of Life Sciences, University of Science and Technology of China, 443 Huangshan Road, Hefei, Anhui 230027, China
- Hefei National Laboratory for Physical Sciences at the Microscales, Hefei, Anhui 230027, China
- Hefei
Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
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Chekan JR, Kwon IH, Agarwal V, Dodd D, Revindran V, Mackie RI, Cann I, Nair SK. Structural and biochemical basis for mannan utilization by Caldanaerobius polysaccharolyticus strain ATCC BAA-17. J Biol Chem 2014; 289:34965-77. [PMID: 25342756 DOI: 10.1074/jbc.m114.579904] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Hemicelluloses, the polysaccharide component of plant cell walls, represent one of the most abundant biopolymers in nature. The most common hemicellulosic constituents of softwoods, such as conifers and cycads, are mannans consisting of a 1,4-linked β-mannopyranosyl main chain with branch decorations. Efforts toward the utilization of hemicellulose for bioconversion into cellulosic biofuels have resulted in the identification of several families of glycoside hydrolases that can degrade mannan. However, effective biofermentation of manno-oligosaccharides is limited by a lack of appropriate uptake route in ethanologenic organisms. Here, we used transcriptome sequencing to gain insights into mannan degradation by the thermophilic anaerobic bacterium Caldanaerobius polysaccharolyticus. The most highly up-regulated genes during mannan fermentation occur in a cluster containing several genes encoding enzymes for efficient mannan hydrolysis as well as a solute-binding protein (CpMnBP1) that exhibits specificity for short mannose polymers but exhibited the flexibility to accommodate branched polysaccharide decorations. Co-crystal structures of CpMnBP1 in complex with mannobiose (1.4-Å resolution) and mannotriose (2.2-Å resolution) revealed the molecular rationale for chain length and oligosaccharide specificity. Calorimetric analysis of several active site variants confirmed the roles of residues critical to the function of CpMnBP1. This work represents the first biochemical characterization of a mannose-specific solute-binding protein and provides a framework for engineering mannan utilization capabilities for microbial fermentation.
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Affiliation(s)
| | | | | | - Dylan Dodd
- Institute for Genomic Biology, Energy Biosciences Institute, University of Illinois, Urbana, Illinois 61801 Microbiology
| | - Vanessa Revindran
- Institute for Genomic Biology, Energy Biosciences Institute, University of Illinois, Urbana, Illinois 61801
| | - Roderick I Mackie
- Institute for Genomic Biology, Animal Sciences, and Energy Biosciences Institute, University of Illinois, Urbana, Illinois 61801
| | - Isaac Cann
- Institute for Genomic Biology, Animal Sciences, and Energy Biosciences Institute, University of Illinois, Urbana, Illinois 61801 Microbiology,
| | - Satish K Nair
- From the Departments of Biochemistry, Institute for Genomic Biology, Center for Biophysics and Computational Biology, and
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Bernardi RC, Cann I, Schulten K. Molecular dynamics study of enhanced Man5B enzymatic activity. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:83. [PMID: 24976862 PMCID: PMC4074406 DOI: 10.1186/1754-6834-7-83] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 05/21/2014] [Indexed: 05/25/2023]
Abstract
BACKGROUND Biofuels are a well-known alternative to the largely used fossil-derived fuels, however the competition with food production is an ethical dilemma. Fortunately a solution is offered by second-generation biofuels which can be produced from agricultural waste or, more specifically, from plant cell wall polysaccharides. The conversion process involves typically enzymatic hydrolysis of lignocellulosic biomass and then separation of its constituent sugars that are further fermented to produce ethanol. Over the years several technologies have been developed that allow this conversion process to occur and the objective is now to make this process cost-competitive in today's markets. RESULTS We observe that reduction of enzymatic efficiency in the presence of gluco-oligosaccharides is associated with a loss of the enzyme's flexibility, the latter being required to bind new substrate, while the presence of manno-oligosaccharides does not pose this problem. Molecular dynamics simulations identify key contacts between substrates and the enzyme catalytic pocket that might be modified through site-directed mutagenesis to prevent loss of enzymatic efficiency. CONCLUSIONS Based on previous experimental studies and the new molecular dynamics data, we suggest that cellohexaose in the active site pocket slows down or even inhibits Man5B enzymatic activity. The assumption of such a mechanism is reasonable since when the gluco-oligosaccharide substrate is attached to the catalytic pocket it takes much longer to leave the pocket and thus prevents other substrates from reaching the active site. The insight is of crucial importance since the inhibition of enzymes by the enzymatic product or by an unsuitable substrate is a major technological problem in reducing the competitiveness of second-generation biofuel production.
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Affiliation(s)
- Rafael C Bernardi
- Beckman Institute, University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801, USA
| | - Isaac Cann
- Energy Biosciences Institute, University of Illinois, 1206 W. Gregory Dr, Urbana, IL 61801, USA
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL 61801, USA
- Department of Animal Science, University of Illinois, 1207 W. Gregory Dr, Urbana, IL 61801, USA
- Institute for Genomic Biology, University of Illinois, 1206 W. Gregory Dr, Urbana, IL 61801, USA
| | - Klaus Schulten
- Beckman Institute, University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801, USA
- Department of Physics, University of Illinois, 1110 W. Green St, Urbana, IL 61801, USA
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