1
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Correa KCS, Facchinatto WM, Habitzreuter FB, Ribeiro GH, Rodrigues LG, Micocci KC, Campana-Filho SP, Colnago LA, Souza DHF. Activity of a Recombinant Chitinase of the Atta sexdens Ant on Different Forms of Chitin and Its Fungicidal Effect against Lasiodiplodia theobromae. Polymers (Basel) 2024; 16:529. [PMID: 38399907 PMCID: PMC10892911 DOI: 10.3390/polym16040529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
This study evaluates the activity of a recombinant chitinase from the leaf-cutting ant Atta sexdens (AsChtII-C4B1) against colloidal and solid α- and β-chitin substrates. 1H NMR analyses of the reaction media showed the formation of N-acetylglucosamine (GlcNAc) as the hydrolysis product. Viscometry analyses revealed a reduction in the viscosity of chitin solutions, indicating that the enzyme decreases their molecular masses. Both solid state 13C NMR and XRD analyses showed minor differences in chitin crystallinity pre- and post-reaction, indicative of partial hydrolysis under the studied conditions, resulting in the formation of GlcNAc and a reduction in molecular mass. However, the enzyme was unable to completely degrade the chitin samples, as they retained most of their solid-state structure. It was also observed that the enzyme acts progressively and with a greater activity on α-chitin than on β-chitin. AsChtII-C4B1 significantly changed the hyphae of the phytopathogenic fungus Lasiodiplodia theobromae, hindering its growth in both solid and liquid media and reducing its dry biomass by approximately 61%. The results demonstrate that AsChtII-C4B1 could be applied as an agent for the bioproduction of chitin derivatives and as a potential antifungal agent.
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Affiliation(s)
- Katia Celina Santos Correa
- Department of Chemistry, Federal University of Sao Carlos, 13565-905 Sao Carlos, Brazil; (K.C.S.C.); (L.G.R.); (K.C.M.)
| | - William Marcondes Facchinatto
- Aveiro Institute of Materials, CICECO, Department of Chemistry, University of Aveiro, St. Santiago, 3810-193 Aveiro, Portugal;
| | - Filipe Biagioni Habitzreuter
- Sao Carlos Institute of Chemistry, University of Sao Paulo, Ave. Trabalhador Sao-carlense 400, 13560-590 Sao Carlos, Brazil; (F.B.H.); (S.P.C.-F.)
| | - Gabriel Henrique Ribeiro
- Brazilian Corporation for Agricultural Research, Embrapa Instrumentation, St. XV de Novembro 1452, 13560-970 Sao Carlos, Brazil; (G.H.R.); (L.A.C.)
| | - Lucas Gomes Rodrigues
- Department of Chemistry, Federal University of Sao Carlos, 13565-905 Sao Carlos, Brazil; (K.C.S.C.); (L.G.R.); (K.C.M.)
| | - Kelli Cristina Micocci
- Department of Chemistry, Federal University of Sao Carlos, 13565-905 Sao Carlos, Brazil; (K.C.S.C.); (L.G.R.); (K.C.M.)
| | - Sérgio Paulo Campana-Filho
- Sao Carlos Institute of Chemistry, University of Sao Paulo, Ave. Trabalhador Sao-carlense 400, 13560-590 Sao Carlos, Brazil; (F.B.H.); (S.P.C.-F.)
| | - Luiz Alberto Colnago
- Brazilian Corporation for Agricultural Research, Embrapa Instrumentation, St. XV de Novembro 1452, 13560-970 Sao Carlos, Brazil; (G.H.R.); (L.A.C.)
| | - Dulce Helena Ferreira Souza
- Department of Chemistry, Federal University of Sao Carlos, 13565-905 Sao Carlos, Brazil; (K.C.S.C.); (L.G.R.); (K.C.M.)
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2
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Lu H, Xue M, Nie X, Luo H, Tan Z, Yang X, Shi H, Li X, Wang T. Glycoside hydrolases in the biodegradation of lignocellulosic biomass. 3 Biotech 2023; 13:402. [PMID: 37982085 PMCID: PMC10654287 DOI: 10.1007/s13205-023-03819-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 10/15/2023] [Indexed: 11/21/2023] Open
Abstract
Lignocellulose is a plentiful and intricate biomass substance made up of cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are polysaccharides characterized by different compositions and degrees of polymerization. As renewable resources, their applications are eco-friendly and can help reduce reliance on petrochemical resources. This review aims to illustrate cellulose, hemicellulose, and their structures and hydrolytic enzymes. To obtain desirable enzyme sources for the high hydrolysis of lignocellulose, highly stable, efficient and thermophilic enzyme sources, and new technologies, such as rational design and machine learning, have been introduced in detail. Generally, the efficient biodegradation of abundant natural biomass into fermentable sugars or other intermediates has great potential in practical applications. Supplementary Information The online version contains supplementary material available at 10.1007/s13205-023-03819-1.
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Affiliation(s)
- Honglin Lu
- Faculty of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003 China
| | - Maoyuan Xue
- Faculty of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003 China
| | - Xinling Nie
- Faculty of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003 China
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass, College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037 China
| | - Hongzheng Luo
- Faculty of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003 China
| | - Zhongbiao Tan
- Faculty of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003 China
| | - Xiao Yang
- Department of Poultry Science, The University of Georgia, Athens, GA 30602 USA
| | - Hao Shi
- Faculty of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003 China
| | - Xun Li
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass, College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037 China
| | - Tao Wang
- Department of Microbiology, The University of Georgia, Athens, GA 30602 USA
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3
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Kuch NJ, Kutschke ME, Parker A, Bingman CA, Fox BG. Contribution of calcium ligands in substrate binding and product release in the Acetovibrio thermocellus glycoside hydrolase family 9 cellulase CelR. J Biol Chem 2023; 299:104655. [PMID: 36990218 PMCID: PMC10149213 DOI: 10.1016/j.jbc.2023.104655] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 03/16/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023] Open
Abstract
Enzymatic deconstruction of lignocellulosic biomass is crucial to establishment of the renewable biofuel and bioproduct economy. Better understanding of these enzymes, including their catalytic and binding domains, and other features offer potential avenues for improvement. Glycoside hydrolase family 9 (GH9) enzymes are attractive targets because they have members that exhibit exo- and endo-cellulolytic activity, processivity of reaction, and thermostability. This study examines a GH9 from Acetovibrio thermocellus ATCC 27405, AtCelR containing a catalytic domain and a carbohydrate binding module (CBM3c). Crystal structures of the enzyme without substrate, bound to cellohexaose (substrate) or cellobiose (product), show the positioning of ligands to calcium and adjacent residues in the catalytic domain that may contribute to substrate binding and facilitate product release. We also investigated the properties of the enzyme engineered to contain an additional carbohydrate binding module (CBM3a). Relative to the catalytic domain alone, CBM3a gave improved binding for Avicel (a crystalline form of cellulose), and catalytic efficiency (kcat/KM) was improved 40× with both CBM3c and CBM3a present. However, because of the molecular weight added by CBM3a, the specific activity of the engineered enzyme was not increased relative to the native construct consisting of only the catalytic and CBM3c domains. This work provides new insight into a potential role of the conserved calcium in the catalytic domain and identifies contributions and limitations of domain engineering for AtCelR and perhaps other GH9 enzymes.
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Affiliation(s)
- Nathaniel J Kuch
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA; DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Mark E Kutschke
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA; DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Alex Parker
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA; DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA; Dane County Youth Apprenticeship Program, Dane County School Consortium, Monona, Wisconsin, USA
| | - Craig A Bingman
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA; DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA; Collaborative Crystallography Core, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Brian G Fox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA; DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA.
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4
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Li P, Wang X, Zhang C, Xu D. Processive binding mechanism of Cel9G from Clostridium cellulovorans: molecular dynamics and free energy landscape investigations. Phys Chem Chem Phys 2023; 25:646-657. [DOI: 10.1039/d2cp04830b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The processive binding mechanism of cellulose by Cel9G from C. cellulovorans was investigated by MD and metadynamics simulations.
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Affiliation(s)
- Penghui Li
- College of Chemistry, MOE Key Laboratory of Green Chemistry and Technology, Sichuan University, Sichuan, Chengdu, 610064, P. R. China
| | - Xin Wang
- College of Chemistry, MOE Key Laboratory of Green Chemistry and Technology, Sichuan University, Sichuan, Chengdu, 610064, P. R. China
| | - Chunchun Zhang
- Analytical & Testing Center, Sichuan University, Sichuan, Chengdu, 610064, P. R. China
| | - Dingguo Xu
- College of Chemistry, MOE Key Laboratory of Green Chemistry and Technology, Sichuan University, Sichuan, Chengdu, 610064, P. R. China
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5
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Zajki-Zechmeister K, Eibinger M, Nidetzky B. Enzyme Synergy in Transient Clusters of Endo- and Exocellulase Enables a Multilayer Mode of Processive Depolymerization of Cellulose. ACS Catal 2022; 12:10984-10994. [PMID: 36082050 PMCID: PMC9442579 DOI: 10.1021/acscatal.2c02377] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 08/12/2022] [Indexed: 11/29/2022]
Abstract
Biological degradation of cellulosic materials relies on the molecular-mechanistic principle that internally chain-cleaving endocellulases work synergistically with chain end-cleaving exocellulases in polysaccharide chain depolymerization. How endo-exo synergy becomes effective in the deconstruction of a solid substrate that presents cellulose chains assembled into crystalline material is an open question of the mechanism, with immediate implications on the bioconversion efficiency of cellulases. Here, based on single-molecule evidence from real-time atomic force microscopy, we discover that endo- and exocellulases engage in the formation of transient clusters of typically three to four enzymes at the cellulose surface. The clusters form specifically at regular domains of crystalline cellulose microfibrils that feature molecular defects in the polysaccharide chain organization. The dynamics of cluster formation correlates with substrate degradation through a multilayer-processive mode of chain depolymerization, overall leading to the directed ablation of single microfibrils from the cellulose surface. Each multilayer-processive step involves the spatiotemporally coordinated and mechanistically concerted activity of the endo- and exocellulases in close proximity. Mechanistically, the cooperativity with the endocellulase enables the exocellulase to pass through its processive cycles ∼100-fold faster than when acting alone. Our results suggest an advanced paradigm of efficient multienzymatic degradation of structurally organized polymer materials by endo-exo synergetic chain depolymerization.
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Affiliation(s)
- Krisztina Zajki-Zechmeister
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
| | - Manuel Eibinger
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
| | - Bernd Nidetzky
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
- Austrian
Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria
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6
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Yappert R, Peters B. Processive Depolymerization Catalysts: A Population Balance Model for Chemistry’s “While” Loop. ACS Catal 2022. [DOI: 10.1021/acscatal.2c01195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Ryan Yappert
- Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Baron Peters
- Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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7
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Tsudome M, Tachioka M, Miyazaki M, Uchimura K, Tsuda M, Takaki Y, Deguchi S. An ultrasensitive nanofiber-based assay for enzymatic hydrolysis and deep-sea microbial degradation of cellulose. iScience 2022; 25:104732. [PMID: 36039358 PMCID: PMC9418596 DOI: 10.1016/j.isci.2022.104732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/10/2022] [Accepted: 07/02/2022] [Indexed: 11/18/2022] Open
Affiliation(s)
- Mikiko Tsudome
- Research Center for Bioscience and Nanoscience, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
| | - Mikako Tachioka
- Research Center for Bioscience and Nanoscience, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
| | - Masayuki Miyazaki
- SUGAR Program, JAMSTEC, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
| | - Kohsuke Uchimura
- Research Center for Bioscience and Nanoscience, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
| | - Miwako Tsuda
- SUGAR Program, JAMSTEC, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
| | - Yoshihiro Takaki
- SUGAR Program, JAMSTEC, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
| | - Shigeru Deguchi
- Research Center for Bioscience and Nanoscience, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
- Corresponding author
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8
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Zajki-Zechmeister K, Kaira GS, Eibinger M, Seelich K, Nidetzky B. Processive Enzymes Kept on a Leash: How Cellulase Activity in Multienzyme Complexes Directs Nanoscale Deconstruction of Cellulose. ACS Catal 2021; 11:13530-13542. [PMID: 34777910 PMCID: PMC8576811 DOI: 10.1021/acscatal.1c03465] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/11/2021] [Indexed: 12/15/2022]
Abstract
Biological deconstruction of polymer materials gains efficiency from the spatiotemporally coordinated action of enzymes with synergetic function in polymer chain depolymerization. To perpetuate enzyme synergy on a solid substrate undergoing deconstruction, the overall attack must alternate between focusing the individual enzymes locally and dissipating them again to other surface sites. Natural cellulases working as multienzyme complexes assembled on a scaffold protein (the cellulosome) maximize the effect of local concentration yet restrain the dispersion of individual enzymes. Here, with evidence from real-time atomic force microscopy to track nanoscale deconstruction of single cellulose fibers, we show that the cellulosome forces the fiber degradation into the transversal direction, to produce smaller fragments from multiple local attacks ("cuts"). Noncomplexed enzymes, as in fungal cellulases or obtained by dissociating the cellulosome, release the confining force so that fiber degradation proceeds laterally, observed as directed ablation of surface fibrils and leading to whole fiber "thinning". Processive cellulases that are enabled to freely disperse evoke the lateral degradation and determine its efficiency. Our results suggest that among natural cellulases, the dispersed enzymes are more generally and globally effective in depolymerization, while the cellulosome represents a specialized, fiber-fragmenting machinery.
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Affiliation(s)
- Krisztina Zajki-Zechmeister
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
| | - Gaurav Singh Kaira
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
- Austrian
Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria
| | - Manuel Eibinger
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
| | - Klara Seelich
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
| | - Bernd Nidetzky
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
- Austrian
Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria
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9
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Abstract
Glycoside hydrolase family 9 (GH9) endoglucanases are important enzymes for cellulose degradation. However, their activity on cellulose is diverse. Here, we cloned and expressed one GH9 enzyme (CalkGH9T) from Clostridium alkalicellulosi in Escherichia coli. CalkGH9T has a modular structure, containing one GH9 catalytic module, two family 3 carbohydrate binding modules, and one type I dockerin domain. CalkGH9T exhibited maximal activity at pH 7.0–8.0 and 55 °C and was resistant to urea and NaCl. It efficiently hydrolyzed carboxymethyl cellulose (CMC) but poorly degraded regenerated amorphous cellulose (RAC). Despite strongly binding to Avicel, CalkGH9T lacked the ability to hydrolyze this substrate. The hydrolysis of CMC by CalkGH9T produced a series of cello-oligomers, with cellotetraose being preferentially released. Similar proportions of soluble and insoluble reducing ends generated by hydrolysis of RAC indicated non-processive activity. Our study extends our knowledge of the molecular mechanism of cellulose hydrolysis by GH9 family endoglucanases with industrial relevance.
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10
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Gado JE, Harrison BE, Sandgren M, Ståhlberg J, Beckham GT, Payne CM. Machine learning reveals sequence-function relationships in family 7 glycoside hydrolases. J Biol Chem 2021; 297:100931. [PMID: 34216620 PMCID: PMC8329511 DOI: 10.1016/j.jbc.2021.100931] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 06/18/2021] [Accepted: 06/29/2021] [Indexed: 11/28/2022] Open
Abstract
Family 7 glycoside hydrolases (GH7) are among the principal enzymes for cellulose degradation in nature and industrially. These enzymes are often bimodular, including a catalytic domain and carbohydrate-binding module (CBM) attached via a flexible linker, and exhibit an active site that binds cello-oligomers of up to ten glucosyl moieties. GH7 cellulases consist of two major subtypes: cellobiohydrolases (CBH) and endoglucanases (EG). Despite the critical importance of GH7 enzymes, there remain gaps in our understanding of how GH7 sequence and structure relate to function. Here, we employed machine learning to gain data-driven insights into relationships between sequence, structure, and function across the GH7 family. Machine-learning models, trained only on the number of residues in the active-site loops as features, were able to discriminate GH7 CBHs and EGs with up to 99% accuracy, demonstrating that the lengths of loops A4, B2, B3, and B4 strongly correlate with functional subtype across the GH7 family. Classification rules were derived such that specific residues at 42 different sequence positions each predicted the functional subtype with accuracies surpassing 87%. A random forest model trained on residues at 19 positions in the catalytic domain predicted the presence of a CBM with 89.5% accuracy. Our machine learning results recapitulate, as top-performing features, a substantial number of the sequence positions determined by previous experimental studies to play vital roles in GH7 activity. We surmise that the yet-to-be-explored sequence positions among the top-performing features also contribute to GH7 functional variation and may be exploited to understand and manipulate function.
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Affiliation(s)
- Japheth E Gado
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, USA; Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | - Brent E Harrison
- Department of Computer Science, University of Kentucky, Lexington, Kentucky, USA
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jerry Ståhlberg
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Gregg T Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | - Christina M Payne
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, USA.
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11
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Nanoscale dynamics of cellulose digestion by the cellobiohydrolase TrCel7A. J Biol Chem 2021; 297:101029. [PMID: 34339742 PMCID: PMC8390518 DOI: 10.1016/j.jbc.2021.101029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 07/26/2021] [Accepted: 07/29/2021] [Indexed: 11/23/2022] Open
Abstract
Understanding the mechanism by which cellulases from bacteria, fungi, and protozoans catalyze the digestion of lignocellulose is important for developing cost-effective strategies for bioethanol production. Cel7A from the fungus Trichoderma reesei is a model exoglucanase that degrades cellulose strands from their reducing ends by processively cleaving individual cellobiose units. Despite being one of the most studied cellulases, the binding and hydrolysis mechanisms of Cel7A are still debated. Here, we used single-molecule tracking to analyze the dynamics of 11,116 quantum dot-labeled TrCel7A molecules binding to and moving processively along immobilized cellulose. Individual enzyme molecules were localized with a spatial precision of a few nanometers and followed for hundreds of seconds. Most enzyme molecules bound to cellulose in a static state and dissociated without detectable movement, whereas a minority of molecules moved processively for an average distance of 39 nm at an average speed of 3.2 nm/s. These data were integrated into a three-state model in which TrCel7A molecules can bind from solution into either static or processive states and can reversibly switch between states before dissociating. From these results, we conclude that the rate-limiting step for cellulose degradation by Cel7A is the transition out of the static state, either by dissociation from the cellulose surface or by initiation of a processive run. Thus, accelerating the transition of Cel7A out of its static state is a potential avenue for improving cellulase efficiency.
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12
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Araújo EA, Dias AHS, Kadowaki MAS, Piyadov V, Pellegrini VOA, Urio MB, Ramos LP, Skaf MS, Polikarpov I. Impact of cellulose properties on enzymatic degradation by bacterial GH48 enzymes: Structural and mechanistic insights from processive Bacillus licheniformis Cel48B cellulase. Carbohydr Polym 2021; 264:118059. [PMID: 33910709 DOI: 10.1016/j.carbpol.2021.118059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 11/29/2022]
Abstract
Processive cellulases are highly efficient molecular engines involved in the cellulose breakdown process. However, the mechanism that processive bacterial enzymes utilize to recruit and retain cellulose strands in the catalytic site remains poorly understood. Here, integrated enzymatic assays, protein crystallography and computational approaches were combined to study the enzymatic properties of the processive BlCel48B cellulase from Bacillus licheniformis. Hydrolytic efficiency, substrate binding affinity, cleavage patterns, and the apparent processivity of bacterial BlCel48B are significantly impacted by the cellulose size and its surface morphology. BlCel48B crystallographic structure was solved with ligands spanning -5 to -2 and +1 to +2 subsites. Statistical coupling analysis and molecular dynamics show that co-evolved residues on active site are critical for stabilizing ligands in the catalytic tunnel. Our results provide mechanistic insights into BlCel48B molecular-level determinants of activity, substrate binding, and processivity on insoluble cellulose, thus shedding light on structure-activity correlations of GH48 family members in general.
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Affiliation(s)
- Evandro A Araújo
- São Carlos Institute of Physics, University of São Paulo (USP), São Carlos 13560-970, São Paulo, Brazil; Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials, Campinas 13083-970, São Paulo, Brazil
| | - Artur Hermano Sampaio Dias
- Institute of Chemistry and Center for Computer in Engineering and Sciences, University of Campinas (UNICAMP), Campinas 13084-862, São Paulo, Brazil
| | - Marco A S Kadowaki
- São Carlos Institute of Physics, University of São Paulo (USP), São Carlos 13560-970, São Paulo, Brazil
| | - Vasily Piyadov
- São Carlos Institute of Physics, University of São Paulo (USP), São Carlos 13560-970, São Paulo, Brazil
| | - Vanessa O A Pellegrini
- São Carlos Institute of Physics, University of São Paulo (USP), São Carlos 13560-970, São Paulo, Brazil
| | - Mateus B Urio
- Graduate Programs in Bioenergy, Chemistry and Chemical Engineering, Federal University of Paraná (UFPR), Curitiba 81531-980, Paraná, Brazil
| | - Luiz P Ramos
- Graduate Programs in Bioenergy, Chemistry and Chemical Engineering, Federal University of Paraná (UFPR), Curitiba 81531-980, Paraná, Brazil
| | - Munir S Skaf
- Institute of Chemistry and Center for Computer in Engineering and Sciences, University of Campinas (UNICAMP), Campinas 13084-862, São Paulo, Brazil
| | - Igor Polikarpov
- São Carlos Institute of Physics, University of São Paulo (USP), São Carlos 13560-970, São Paulo, Brazil.
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13
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Nemmaru B, Ramirez N, Farino CJ, Yarbrough JM, Kravchenko N, Chundawat SPS. Reduced type-A carbohydrate-binding module interactions to cellulose I leads to improved endocellulase activity. Biotechnol Bioeng 2020; 118:1141-1151. [PMID: 33245142 DOI: 10.1002/bit.27637] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/12/2020] [Accepted: 11/15/2020] [Indexed: 12/24/2022]
Abstract
Dissociation of nonproductively bound cellulolytic enzymes from cellulose is hypothesized to be a key rate-limiting factor impeding cost-effective biomass conversion to fermentable sugars. However, the role of carbohydrate-binding modules (CBMs) in enabling nonproductive enzyme binding is not well understood. Here, we examine the subtle interplay of CBM binding and cellulose hydrolysis activity for three models type-A CBMs (Families 1, 3a, and 64) tethered to multifunctional endoglucanase (CelE) on two distinct cellulose allomorphs (i.e., cellulose I and III). We generated a small library of mutant CBMs with varying cellulose affinity, as determined by equilibrium binding assays, followed by monitoring cellulose hydrolysis activity of CelE-CBM fusion constructs. Finally, kinetic binding assays using quartz crystal microbalance with dissipation were employed to measure CBM adsorption and desorption rate constants k on and k off , respectively, towards nanocrystalline cellulose derived from both allomorphs. Overall, our results indicate that reduced CBM equilibrium binding affinity towards cellulose I alone, resulting from increased desorption rates ( k off ) and reduced effective adsorption rates ( nk on ), is correlated to overall improved endocellulase activity. Future studies could employ similar approaches to unravel the role of CBMs in nonproductive enzyme binding and develop improved cellulolytic enzymes for industrial applications.
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Affiliation(s)
| | - Nicholas Ramirez
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Cindy J Farino
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - John M Yarbrough
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | - Nicholas Kravchenko
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Shishir P S Chundawat
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
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14
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Kumar K, Singh S, Sharma K, Goyal A. Computational modeling and small-angle X-ray scattering based structure analysis and identifying ligand cleavage mechanism by processive endocellulase of family 9 glycoside hydrolase (HtGH9) from Hungateiclostridium thermocellum ATCC 27405. J Mol Graph Model 2020; 103:107808. [PMID: 33248343 DOI: 10.1016/j.jmgm.2020.107808] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 11/13/2020] [Accepted: 11/13/2020] [Indexed: 11/16/2022]
Abstract
The cellulases of family 9 glycoside hydrolase with subtle difference in amino acid sequence have shown different types of catalytic activities such as endo-, exo- or processive endocellulase. However, the reason behind the different types of catalytic activities still unclear. In this study, the processive endocellulase, HtGH9 of family 9 GH from Hungateiclostridium thermocellum was modeled by homology modeling. The catalytic module (HtGH9t) of HtGH9 modeled structure displayed the (α/α)6 barrel topology and associated family 3 carbohydrate binding module (HtCBM3c) displayed β-sandwich fold. Ramachandran plot of HtGH9 modeled structure displayed all the amino acid residues in allowed region except Asn225 and Asp317. Secondary structure analysis of modeled HtGH9 showed the presence of 41.3% α-helices and 11.0% β-strands which was validated through circular dichroism analysis that showed the presence of 42.6% α-helices and 14.5% β-strands. Molecular Dynamic (MD) simulation of HtGH9 structure for 50 ns showed Root Mean Square Deviation (RMSD), 0.84 nm and radius of gyration (Rg) 3.1 nm. The Small-angle X-ray scattering of HtGH9 confirmed the monodisperse state. The radius of gyration for globular shape (Rg) was 5.50 ± 0.15 nm and for rod shape (Rc) by Guinier plot was 2.0 nm. The loop formed by amino acid residues, 264-276 towards one end of the catalytic site of HtGH9 forms a barrier, that blocks the non-reducing end of the cellulose chain causing the processive cleavage resulting in the release of cellotetraose. The position of the corresponding loop in cellulases of family 9 GH is responsible for different types of cleavage patterns.
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Affiliation(s)
- Krishan Kumar
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Shubha Singh
- Division of Biological Sciences and Engineering, Netaji Subhas University of Technology, Delhi, 110078, India
| | - Kedar Sharma
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India; Laboratory of Small Molecules & Macro Molecular Crystallography, Department of Bioengineering, Indian Institute of Technology Gandhinagar, Gandhinagar, 382355, India
| | - Arun Goyal
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
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15
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Glycoside hydrolase family 18 chitinases: The known and the unknown. Biotechnol Adv 2020; 43:107553. [DOI: 10.1016/j.biotechadv.2020.107553] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/09/2020] [Accepted: 04/20/2020] [Indexed: 12/13/2022]
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16
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Gluck-Thaler E, Cerutti A, Perez-Quintero AL, Butchacas J, Roman-Reyna V, Madhavan VN, Shantharaj D, Merfa MV, Pesce C, Jauneau A, Vancheva T, Lang JM, Allen C, Verdier V, Gagnevin L, Szurek B, Beckham GT, De La Fuente L, Patel HK, Sonti RV, Bragard C, Leach JE, Noël LD, Slot JC, Koebnik R, Jacobs JM. Repeated gain and loss of a single gene modulates the evolution of vascular plant pathogen lifestyles. SCIENCE ADVANCES 2020; 6:6/46/eabc4516. [PMID: 33188025 PMCID: PMC7673761 DOI: 10.1126/sciadv.abc4516] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 09/30/2020] [Indexed: 05/21/2023]
Abstract
Vascular plant pathogens travel long distances through host veins, leading to life-threatening, systemic infections. In contrast, nonvascular pathogens remain restricted to infection sites, triggering localized symptom development. The contrasting features of vascular and nonvascular diseases suggest distinct etiologies, but the basis for each remains unclear. Here, we show that the hydrolase CbsA acts as a phenotypic switch between vascular and nonvascular plant pathogenesis. cbsA was enriched in genomes of vascular phytopathogenic bacteria in the family Xanthomonadaceae and absent in most nonvascular species. CbsA expression allowed nonvascular Xanthomonas to cause vascular blight, while cbsA mutagenesis resulted in reduction of vascular or enhanced nonvascular symptom development. Phylogenetic hypothesis testing further revealed that cbsA was lost in multiple nonvascular lineages and more recently gained by some vascular subgroups, suggesting that vascular pathogenesis is ancestral. Our results overall demonstrate how the gain and loss of single loci can facilitate the evolution of complex ecological traits.
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Affiliation(s)
- Emile Gluck-Thaler
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, USA
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Aude Cerutti
- LIPM, Université de Toulouse, INRAE, CNRS, Université Paul Sabatier, Castanet-Tolosan, France
| | | | - Jules Butchacas
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, USA
- Infectious Disease Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Verónica Roman-Reyna
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, USA
- Infectious Disease Institute, The Ohio State University, Columbus, OH 43210, USA
| | | | - Deepak Shantharaj
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | - Marcus V Merfa
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | - Céline Pesce
- IRD, CIRAD, Université Montpellier, IPME, Montpellier, France
- Earth & Life Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
- HM Clause (Limagrain group), Davis, CA, 95618, USA
| | - Alain Jauneau
- Institut Fédératif de Recherche 3450, Plateforme Imagerie, Pôle de Biotechnologie Végétale, Castanet-Tolosan, France
| | - Taca Vancheva
- IRD, CIRAD, Université Montpellier, IPME, Montpellier, France
- Earth & Life Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Jillian M Lang
- Agricultural Biology, Colorado State University, Fort Collins, CO, USA
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Valerie Verdier
- IRD, CIRAD, Université Montpellier, IPME, Montpellier, France
| | - Lionel Gagnevin
- IRD, CIRAD, Université Montpellier, IPME, Montpellier, France
| | - Boris Szurek
- IRD, CIRAD, Université Montpellier, IPME, Montpellier, France
| | - Gregg T Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Leonardo De La Fuente
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | | | - Ramesh V Sonti
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Claude Bragard
- Earth & Life Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Jan E Leach
- Agricultural Biology, Colorado State University, Fort Collins, CO, USA
| | - Laurent D Noël
- LIPM, Université de Toulouse, INRAE, CNRS, Université Paul Sabatier, Castanet-Tolosan, France
| | - Jason C Slot
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, USA
- Infectious Disease Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Ralf Koebnik
- IRD, CIRAD, Université Montpellier, IPME, Montpellier, France.
| | - Jonathan M Jacobs
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, USA.
- Infectious Disease Institute, The Ohio State University, Columbus, OH 43210, USA
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17
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Østby H, Hansen LD, Horn SJ, Eijsink VGH, Várnai A. Enzymatic processing of lignocellulosic biomass: principles, recent advances and perspectives. J Ind Microbiol Biotechnol 2020; 47:623-657. [PMID: 32840713 PMCID: PMC7658087 DOI: 10.1007/s10295-020-02301-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 07/30/2020] [Indexed: 02/06/2023]
Abstract
Efficient saccharification of lignocellulosic biomass requires concerted development of a pretreatment method, an enzyme cocktail and an enzymatic process, all of which are adapted to the feedstock. Recent years have shown great progress in most aspects of the overall process. In particular, increased insights into the contributions of a wide variety of cellulolytic and hemicellulolytic enzymes have improved the enzymatic processing step and brought down costs. Here, we review major pretreatment technologies and different enzyme process setups and present an in-depth discussion of the various enzyme types that are currently in use. We pay ample attention to the role of the recently discovered lytic polysaccharide monooxygenases (LPMOs), which have led to renewed interest in the role of redox enzyme systems in lignocellulose processing. Better understanding of the interplay between the various enzyme types, as they may occur in a commercial enzyme cocktail, is likely key to further process improvements.
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Affiliation(s)
- Heidi Østby
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Aas, Norway
| | - Line Degn Hansen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Aas, Norway
| | - Svein J Horn
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Aas, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Aas, Norway
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Aas, Norway.
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18
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Haske-Cornelius O, Hartmann A, Brunner F, Pellis A, Bauer W, Nyanhongo GS, Guebitz GM. Effects of enzymes on the refining of different pulps. J Biotechnol 2020; 320:1-10. [PMID: 32553829 DOI: 10.1016/j.jbiotec.2020.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 05/29/2020] [Accepted: 06/09/2020] [Indexed: 11/30/2022]
Abstract
Comparative studies of the effects of two commercial enzyme formulations on fiber refining were conducted. Extensive basic characterisation of the enzymes involved, assessment of their hydrolytic activities on different model substrates as well as on different pulps (softwood sulfate, softwood sulfite, hardwood sulfate) were evaluated. Both enzyme formulations showed endoglucanase as well as some xylanase and β-glucosidase activity. In addition, Enzyme A reached a CMC end viscosity of 19.5 mPa compared to 11.1 mPa for Enzyme B. Reducing sugar release almost doubled from 695 μmol mL-1 for hardwood sulfate pulp to 1300 μmol mL-1 for softwood sulfite pulp with Enzyme B under the same conditions. Enzyme A increased the degree of refining even under non-ideal conditions from 23 °SR to up to 50 °SR. Further characterization of hand sheets, made from enzyme pre-treated and refined cellulose fibers with Enzyme A and B, showed that Enzyme A had the best effects leading to hand sheets with increased tensile strength and low air permeability. In summary, the increase in the degree of refining seen for Enzyme A correlated to higher xylanase and β-glucosidase activity and lower endoglucanase activity.
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Affiliation(s)
- Oskar Haske-Cornelius
- Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 20, 3430, Tulln an der Donau, Austria
| | - Alexandra Hartmann
- Graz University of Technology, Institute of Paper, Pulp and Fiber Technology, Inffeldgasse 23, Graz, 8010, Austria
| | - Florian Brunner
- Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 20, 3430, Tulln an der Donau, Austria
| | - Alessandro Pellis
- Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 20, 3430, Tulln an der Donau, Austria
| | - Wolfgang Bauer
- Graz University of Technology, Institute of Paper, Pulp and Fiber Technology, Inffeldgasse 23, Graz, 8010, Austria
| | - Gibson S Nyanhongo
- Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 20, 3430, Tulln an der Donau, Austria.
| | - Georg M Guebitz
- Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 20, 3430, Tulln an der Donau, Austria; Austrian Centre of Industrial Biotechnology, Konrad-Lorenz-Strasse 20, 3430, Tulln an der Donau, Austria
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19
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Okazaki KI, Nakamura A, Iino R. Chemical-State-Dependent Free Energy Profile from Single-Molecule Trajectories of Biomolecular Motors: Application to Processive Chitinase. J Phys Chem B 2020; 124:6475-6487. [DOI: 10.1021/acs.jpcb.0c02698] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Kei-ichi Okazaki
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, 444-8585, Japan
| | - Akihiko Nakamura
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
- Department of Applied Life Sciences, Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Ryota Iino
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
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20
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Abstract
Extracellular polysaccharides and glycoproteins of pathogenic bacteria assist in adherence, autoaggregation, biofilm formation, and host immune system evasion. As a result, considerable research in the field of glycobiology is dedicated to study the composition and function of glycans associated with virulence, as well as the enzymes involved in their biosynthesis with the aim to identify novel antibiotic targets. Especially, insights into the enzyme mechanism, substrate binding, and transition-state structures are valuable as a starting point for rational inhibitor design. An intriguing aspect of enzymes that generate or process polysaccharides and glycoproteins is the level of processivity. The existence of enzymatic processivity reflects the need for regulation of the final glycan/glycoprotein length and structure, depending on the role they perform. In this Review, we describe the currently reported examples of various processive enzymes involved in polymerization and transfer of sugar moieties, predominantly in bacterial pathogens, with a focus on the biochemical methods, to showcase the importance of studying processivity for understanding the mechanism.
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Affiliation(s)
- Liubov Yakovlieva
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Marthe T. C. Walvoort
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
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21
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Hamre AG, Sørlie M. Kinetic relationships with processivity in Serratia marcescens family 18 glycoside hydrolases. Biochem Biophys Res Commun 2020; 521:120-124. [PMID: 31629467 DOI: 10.1016/j.bbrc.2019.10.089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 10/10/2019] [Indexed: 10/25/2022]
Abstract
In nature, recalcitrant polysaccharides such as chitin and cellulose are degraded by glycoside hydrolases (GH) that act synergistically through different modes of action including attack from reducing-end and nonreducing-end (exo-mode) and random (endo-mode) on single polysaccharide chains. Both modes can be combined with a processive mechanism where the GH remain bound to the polysaccharide to perform multiple catalytic steps before dissociation into the solution. In this work, we have determined association rate constants and their activation paramaters for three co-evolved GHs from Serratia marcescens (SmChiA, SmChiB, and SmChiC) with an oligomeric substrate. Interestingly, we observe a positive correlation between the association rate constants and processive ability for the GHs. Previously, a positive correlation has been observed between substrate binding affinity and processive ability. SmChiA with highest processive ability of the three GHs bind with a kon of 11.5 ± 0.2 μM-1s-1, which is five-fold and 130-fold faster than SmChiB (less processive) and SmChiC (nonprocessive), respectively.
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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
| | - Morten Sørlie
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, N-1432 Ås, Norway.
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22
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Abstract
Cellulase enzymes deconstruct recalcitrant cellulose into soluble sugars, making them a biocatalyst of biotechnological interest for use in the nascent lignocellulosic bioeconomy. Cellobiohydrolases (CBHs) are cellulases capable of liberating many sugar molecules in a processive manner without dissociating from the substrate. Within the complete processive cycle of CBHs, dissociation from the cellulose substrate is rate limiting, but the molecular mechanism of this step is unknown. Here, we present a direct comparison of potential molecular mechanisms for dissociation via Hamiltonian replica exchange molecular dynamics of the model fungal CBH, Trichoderma reesei Cel7A. Computational rate estimates indicate that stepwise cellulose dethreading from the binding tunnel is 4 orders of magnitude faster than a clamshell mechanism, in which the substrate-enclosing loops open and release the substrate without reversing. We also present the crystal structure of a disulfide variant that covalently links substrate-enclosing loops on either side of the substrate-binding tunnel, which constitutes a CBH that can only dissociate via stepwise dethreading. Biochemical measurements indicate that this variant has a dissociation rate constant essentially equivalent to the wild type, implying that dethreading is likely the predominant mechanism for dissociation.
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23
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Harmsen RAG, Tuveng TR, Antonsen SG, Eijsink VGH, Sørlie M. Can we make Chitosan by Enzymatic Deacetylation of Chitin? Molecules 2019; 24:E3862. [PMID: 31717737 PMCID: PMC6864559 DOI: 10.3390/molecules24213862] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/23/2019] [Accepted: 10/23/2019] [Indexed: 11/17/2022] Open
Abstract
Chitin, an insoluble linear polymer of β-1,4-N-acetyl-d-glucosamine (GlcNAc; A), can be converted to chitosan, a soluble heteropolymer of GlcNAc and d-glucosamine (GlcN; D) residues, by partial deacetylation. In nature, deacetylation of chitin is catalyzed by enzymes called chitin deacetylases (CDA) and it has been proposed that CDAs could be used to produce chitosan. In this work, we show that CDAs can remove up to approximately 10% of N-acetyl groups from two different (α and β) chitin nanofibers, but cannot produce chitosan.
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Affiliation(s)
| | | | | | | | - Morten Sørlie
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, N-1432 Ås, Norway (T.R.T.); (S.G.A.)
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24
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Kumar K, Singal S, Goyal A. Role of carbohydrate binding module (CBM3c) of GH9 β-1,4 endoglucanase (Cel9W) from Hungateiclostridium thermocellum ATCC 27405 in catalysis. Carbohydr Res 2019; 484:107782. [DOI: 10.1016/j.carres.2019.107782] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/06/2019] [Accepted: 08/20/2019] [Indexed: 11/30/2022]
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25
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Kari J, Christensen SJ, Andersen M, Baiget SS, Borch K, Westh P. A practical approach to steady-state kinetic analysis of cellulases acting on their natural insoluble substrate. Anal Biochem 2019; 586:113411. [PMID: 31520594 DOI: 10.1016/j.ab.2019.113411] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/26/2019] [Accepted: 08/28/2019] [Indexed: 10/26/2022]
Abstract
Measurement of steady-state rates (vSS) is straightforward in standard enzymology with soluble substrate, and it has been instrumental for comparative biochemical analyses within this area. For insoluble substrate, however, experimental values of vss remain controversial, and this has strongly limited the amount and quality of comparative analyses for cellulases and other enzymes that act on the surface of an insoluble substrate. In the current work, we have measured progress curves over a wide range of conditions for two cellulases, TrCel6A and TrCel7A from Trichoderma reesei, acting on their natural, insoluble substrate, cellulose. Based on this, we consider practical compromises for the determination of experimental vSS values, and propose a basic protocol that provides representative reaction rates and is experimentally simple so that larger groups of enzymes and conditions can be readily assayed with standard laboratory equipment. We surmise that the suggested experimental approach can be useful in comparative biochemical studies of cellulases; an area that remains poorly developed.
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Affiliation(s)
- Jeppe Kari
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800, Kgs. Lyngby, Denmark
| | - Stefan Jarl Christensen
- Department of Science and Environment, Roskilde University, Universitetsvej, Build. 28.C, DK-4000, Roskilde, Denmark
| | - Morten Andersen
- Department of Science and Environment, Roskilde University, Universitetsvej, Build. 28.C, DK-4000, Roskilde, Denmark
| | | | - Kim Borch
- Novozymes A/S, Krogshøjvej 36, DK-2880, Bagsværd, Denmark
| | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800, Kgs. Lyngby, Denmark.
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26
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Jana S, Hamre AG, Eijsink VGH, Sørlie M, Payne CM. Polar residues lining the binding cleft of a Serratia marcescens family 18 chitinase position the substrate for attack and stabilize associative interactions. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1657600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Suvamay Jana
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY, USA
| | - Anne Grethe Hamre
- Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Vincent G. H. Eijsink
- Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Morten Sørlie
- Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Christina M. Payne
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY, USA
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27
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A biochemical comparison of fungal GH6 cellobiohydrolases. Biochem J 2019; 476:2157-2172. [DOI: 10.1042/bcj20190185] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 07/14/2019] [Accepted: 07/16/2019] [Indexed: 02/02/2023]
Abstract
AbstractCellobiohydrolases (CBHs) from glycoside hydrolase family 6 (GH6) make up an important part of the secretome in many cellulolytic fungi. They are also of technical interest, particularly because they are part of the enzyme cocktails that are used for the industrial breakdown of lignocellulosic biomass. Nevertheless, functional studies of GH6 CBHs are scarce and focused on a few model enzymes. To elucidate functional breadth among GH6 CBHs, we conducted a comparative biochemical study of seven GH6 CBHs originating from fungi living in different habitats, in addition to one enzyme variant. The enzyme sequences were investigated by phylogenetic analyses to ensure that they were not closely related phylogenetically. The selected enzymes were all heterologously expressed in Aspergillus oryzae, purified and thoroughly characterized biochemically. This approach allowed direct comparisons of functional data, and the results revealed substantial variability. For example, the adsorption capacity on cellulose spanned two orders of magnitude and kinetic parameters, derived from two independent steady-state methods also varied significantly. While the different functional parameters covered wide ranges, they were not independent since they changed in parallel between two poles. One pole was characterized by strong substrate interactions, high adsorption capacity and low turnover number while the other showed weak substrate interactions, poor adsorption and high turnover. The investigated enzymes essentially defined a continuum between these two opposites, and this scaling of functional parameters raises interesting questions regarding functional plasticity and evolution of GH6 CBHs.
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Hefferon KL, Cantero‐Tubilla B, Brady J, Wilson D. Aromatic residues surrounding the active site tunnel of TfCel48A influence activity, processivity, and synergistic interactions with other cellulases. Biotechnol Bioeng 2019; 116:2463-2472. [DOI: 10.1002/bit.27086] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 05/29/2019] [Accepted: 06/02/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Kathleen L. Hefferon
- Department of Cellular and Molecular GeneticsCornell University Ithaca New York
- Department of Food Science and TechnologyCornell University Ithaca New York
| | - Borja Cantero‐Tubilla
- Robert Frederick Smith School of Chemical and Biomolecular EngineeringCornell University Ithaca New York
| | - John Brady
- Department of Food Science and TechnologyCornell University Ithaca New York
| | - David Wilson
- Department of Cellular and Molecular GeneticsCornell University Ithaca New York
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Sharma K, Fontes CMGA, Najmudin S, Goyal A. Molecular organization and protein stability of the Clostridium thermocellum glucuronoxylan endo-β-1,4-xylanase of family 30 glycoside hydrolase in solution. J Struct Biol 2019; 206:335-344. [PMID: 30959107 DOI: 10.1016/j.jsb.2019.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 04/02/2019] [Accepted: 04/04/2019] [Indexed: 11/19/2022]
Abstract
Glucuronoxylan-β-1,4-xylanohydrolase from Clostridium thermocellum (CtXynGH30) hydrolyzes β-1,4-xylosidic linkages in 4-O-Methyl-D-glucuronoxylan. CtXynGH30 comprises an N-terminal catalytic domain, CtXyn30A, joined by a typical linker sequence to a family 6 carbohydrate-binding module, termed CtCBM6. ITC, mass spectrometric and enzyme activity analyses of CtXyn30A:CtCBM6 (1:1 M ratio), CtXyn30A and CtXynGH30 showed that the linker peptide plays a key role in connecting and orienting CtXyn30A and CtCBM6 modules resulting in the enhanced activity of CtXynGH30. To visualize the disposition of the two protein domains of CtXynGH30, SAXS analysis revealed that CtXynGH30 is monomeric and has a boot-shaped molecular envelope in solution with a Dmax of 18 nm and Rg of 3.6 nm. Kratky plot displayed the protein in a fully folded and flexible state. The ab initio derived dummy atom model of CtXynGH30 superposed well with the modelled structure.
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Affiliation(s)
- Kedar Sharma
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Carlos M G A Fontes
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Shabir Najmudin
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Arun Goyal
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
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Amos RA, Mohnen D. Critical Review of Plant Cell Wall Matrix Polysaccharide Glycosyltransferase Activities Verified by Heterologous Protein Expression. FRONTIERS IN PLANT SCIENCE 2019; 10:915. [PMID: 31379900 PMCID: PMC6646851 DOI: 10.3389/fpls.2019.00915] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 06/27/2019] [Indexed: 05/02/2023]
Abstract
The life cycle and development of plants requires the biosynthesis, deposition, and degradation of cell wall matrix polysaccharides. The structures of the diverse cell wall matrix polysaccharides influence commercially important properties of plant cells, including growth, biomass recalcitrance, organ abscission, and the shelf life of fruits. This review is a comprehensive summary of the matrix polysaccharide glycosyltransferase (GT) activities that have been verified using in vitro assays following heterologous GT protein expression. Plant cell wall (PCW) biosynthetic GTs are primarily integral transmembrane proteins localized to the endoplasmic reticulum and Golgi of the plant secretory system. The low abundance of these enzymes in plant tissues makes them particularly difficult to purify from native plant membranes in quantities sufficient for enzymatic characterization, which is essential to study the functions of the different GTs. Numerous activities in the synthesis of the major cell wall matrix glycans, including pectins, xylans, xyloglucan, mannans, mixed-linkage glucans (MLGs), and arabinogalactan components of AGP proteoglycans have been mapped to specific genes and multi-gene families. Cell wall GTs include those that synthesize the polymer backbones, those that elongate side branches with extended glycosyl chains, and those that add single monosaccharide linkages onto polysaccharide backbones and/or side branches. Three main strategies have been used to identify genes encoding GTs that synthesize cell wall linkages: analysis of membrane fractions enriched for cell wall biosynthetic activities, mutational genetics approaches investigating cell wall compositional phenotypes, and omics-directed identification of putative GTs from sequenced plant genomes. Here we compare the heterologous expression systems used to produce, purify, and study the enzyme activities of PCW GTs, with an emphasis on the eukaryotic systems Nicotiana benthamiana, Pichia pastoris, and human embryonic kidney (HEK293) cells. We discuss the enzymatic properties of GTs including kinetic rates, the chain lengths of polysaccharide products, acceptor oligosaccharide preferences, elongation mechanisms for the synthesis of long-chain polymers, and the formation of GT complexes. Future directions in the study of matrix polysaccharide biosynthesis are proposed.
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Affiliation(s)
- Robert A. Amos
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, United States
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
| | - Debra Mohnen
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, United States
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
- *Correspondence: Debra Mohnen
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Han F, Liu Y, E J, Guan S, Han W, Shan Y, Wang S, Zhang H. Effects of Tyr555 and Trp678 on the processivity of cellobiohydrolase A from Ruminiclostridium thermocellum: A simulation study. Biopolymers 2018; 109:e23238. [PMID: 30484856 DOI: 10.1002/bip.23238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/21/2018] [Accepted: 10/01/2018] [Indexed: 12/12/2022]
Abstract
Cellobiohydrolase A from Ruminiclostridium thermocellum (Cbh9A) is a processive exoglucanase from family 9 and is an important cellobiohydrolase that hydrolyzes cello-oligosaccharide into cellobiose. Residues Tyr555 and Trp678 considerably affect catalytic activity, but their mechanisms are still unknown. To investigate how the Tyr555 and Trp678 affect the processivity of Cbh9A, conventional molecular dynamics, steered molecular dynamics, and free energy calculation were performed to simulate the processive process of wild type (WT)-Cbh9A, Y555S mutant, and W678G mutant. Analysis of simulation results suggests that the binding free energies between the substrate and WT-Cbh9A are lower than those of Y555S and W678G mutants. The pull forces and energy barrier in Y555S and W678G mutants also reduced significantly during the steered molecular dynamics (SMD) simulation compared with that of the WT-Cbh9A. And the potential mean force calculations showed that the pulling energy barrier of Y555S and W678G mutants is much lower than that of WT-Cbh9A.
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Affiliation(s)
- Fei Han
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Ye Liu
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, National Engineering Laboratory of AIDS Vaccine, College of Life Science, Jilin University, Changchun, China
| | - Jingwen E
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Shanshan Guan
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, National Engineering Laboratory of AIDS Vaccine, College of Life Science, Jilin University, Changchun, China
| | - Weiwei Han
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, National Engineering Laboratory of AIDS Vaccine, College of Life Science, Jilin University, Changchun, China
| | - Yaming Shan
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, National Engineering Laboratory of AIDS Vaccine, College of Life Science, Jilin University, Changchun, China
| | - Song Wang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Hao Zhang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
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Rabinovich ML, Melnik MS, Herner ML, Voznyi YV, Vasilchenko LG. Predominant Nonproductive Substrate Binding by Fungal Cellobiohydrolase I and Implications for Activity Improvement. Biotechnol J 2018; 14:e1700712. [PMID: 29781240 DOI: 10.1002/biot.201700712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 05/08/2018] [Indexed: 12/20/2022]
Abstract
Enzymatic conversion of the most abundant renewable source of organic compounds, cellulose to fermentable sugars is attractive for production of green fuels and chemicals. The major component of industrial enzyme systems, cellobiohydrolase I from Hypocrea jecorina (Trichoderma reesei) (HjCel7A) processively splits disaccharide units from the reducing ends of tightly packed cellulose chains. HjCel7A consists of a catalytic domain (CD) and a carbohydrate-binding module (CBM) separated by a linker peptide. A tunnel-shaped substrate-binding site in the CD includes nine subsites for β-d-glucose units, seven of which (-7 to -1) precede the catalytic center. Low catalytic activity of Cel7A is the bottleneck and the primary target for improvement. Here it is shown for the first time that, in spite of much lower apparent kcat of HjCel7A at the hydrolysis of β-1,4-glucosidic linkages in the fluorogenic cellotetra- and -pentaose compared to the structurally related endoglucanase I (HjCel7B), the specificity constants (catalytic efficiency) kcat /Km for both enzymes are almost equal in these reactions. The observed activity difference appears from strong nonproductive substrate binding by HjCel7A, particularly significant for MU-β-cellotetraose (MUG4 ). Interaction of substrates with the subsites -6 and -5 proximal to the nonconserved Gln101 residue in HjCel7A decreases Km,ap by >1500 times. HjCel7A can be nonproductively bound onto cellulose surface with Kd ≈2-9 nM via CBM and CD that captures six terminal glucose units of cellulose chain. Decomposition of this nonproductive complex can determine the rate of cellulose conversion. MUG4 is a promising substrate to select active cellobiohydrolase I variants with reduced nonproductive substrate binding.
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Affiliation(s)
- Mikhail L Rabinovich
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Maria S Melnik
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Mikhail L Herner
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Yakov V Voznyi
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia
| | - Lilia G Vasilchenko
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
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Zhai R, Hu J, Saddler JN. The inhibition of hemicellulosic sugars on cellulose hydrolysis are highly dependant on the cellulase productive binding, processivity, and substrate surface charges. BIORESOURCE TECHNOLOGY 2018; 258:79-87. [PMID: 29524690 DOI: 10.1016/j.biortech.2017.12.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 12/02/2017] [Accepted: 12/04/2017] [Indexed: 05/24/2023]
Abstract
In this study, the influence of major hemicellulosic sugars (mannose and xylose) on cellulose hydrolysis and major enzyme activities were evaluated by using both commercial enzyme cocktail and purified cellulase monocomponents over a "library" of cellulosic substrates. Surprisingly, the results showed that unlike glucose, mannose/xylose did not inhibit individual cellulase activities but significantly decreased their hydrolytic performance on cellulose substrates. When various enzyme-substrate interactions (e.g. adsorption/desorption, productive binding, and processive moving) were evaluated, it appeared that these hemicellulosic sugars significantly reduced the productive binding and processivity of Cel7A, which in turn limited cellulase hydrolytic efficacy. Among a range of major cellulose characteristics (e.g. crystallinity, degree of polymerization, accessibility, and surface charges), the acid group content of the cellulosic substrates seemed to be the main driver that determined the extent of hemicellulosic sugar inhibition. Our results provided new insights for better understanding the sugar inhibition mechanisms of cellulose hydrolysis.
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Affiliation(s)
- Rui Zhai
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing 210094, China; Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada
| | - Jinguang Hu
- Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada.
| | - Jack N Saddler
- Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada
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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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Silveira RL, Skaf MS. Concerted motions and large-scale structural fluctuations of Trichoderma reesei Cel7A cellobiohydrolase. Phys Chem Chem Phys 2018; 20:7498-7507. [PMID: 29488531 DOI: 10.1039/c8cp00101d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cellobiohydrolases (CBHs) are key enzymes for the saccharification of cellulose and play major roles in industrial settings for biofuel production. The catalytic core domain of these enzymes exhibits a long and narrow binding tunnel capable of binding glucan chains from crystalline cellulose and processively hydrolyze them. The binding cleft is topped by a set of loops, which are believed to play key roles in substrate binding and cleavage processivity. Here, we present an analysis of the loop motions of the Trichoderma reesei Cel7A catalytic core domain (TrCel7A) using conventional and accelerated molecular dynamics simulations. We observe that the loops exhibit highly coupled fluctuations and cannot move independently of each other. In the absence of a substrate, the characteristic large amplitude dynamics of TrCel7A consists of breathing motions, where the loops undergo open-and-close fluctuations. Upon substrate binding, the open-close fluctuations of the loops are quenched and one of the loops moves parallel to the binding site, possibly to allow processive motion along the glucan chain. Using microsecond accelerated molecular dynamics, we observe large-scale fluctuations of the loops (up to 37 Å) and the entire exposure of the TrCel7A binding site in the absence of the substrate, resembling an endoglucanase. These results suggest that the initial CBH-substrate contact and substrate recognition by the enzyme are similar to that of endoglucanases and, once bound to the substrate, the loops remain closed for proper enzymatic activity.
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Affiliation(s)
- Rodrigo L Silveira
- Institute of Chemistry, University of Campinas, Cx. P. 6154, Campinas, 13084-862, SP, Brazil.
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Abstract
Glycoside Hydrolase Family 7 cellobiohydrolases (GH7 CBHs) catalyze cellulose depolymerization in cellulolytic eukaryotes, making them key discovery and engineering targets. However, there remains a lack of robust structure–activity relationships for these industrially important cellulases. Here, we compare CBHs from Trichoderma reesei (TrCel7A) and Penicillium funiculosum (PfCel7A), which exhibit a multi-modular architecture consisting of catalytic domain (CD), carbohydrate-binding module, and linker. We show that PfCel7A exhibits 60% greater performance on biomass than TrCel7A. To understand the contribution of each domain to this improvement, we measure enzymatic activity for a library of CBH chimeras with swapped subdomains, demonstrating that the enhancement is mainly caused by PfCel7A CD. We solve the crystal structure of PfCel7A CD and use this information to create a second library of TrCel7A CD mutants, identifying a TrCel7A double mutant with near-equivalent activity to wild-type PfCel7A. Overall, these results reveal CBH regions that enable targeted activity improvements. Cellobiohydrolases (CBHs) are critical for natural and industrial biomass degradation but their structure–activity relationships are not fully understood. Here, the authors present the biochemical and structural characterization of two CBHs, identifying protein regions that confer enhanced CBH activity.
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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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Wu B, Zheng S, Pedroso MM, Guddat LW, Chang S, He B, Schenk G. Processivity and enzymatic mechanism of a multifunctional family 5 endoglucanase from Bacillus subtilis BS-5 with potential applications in the saccharification of cellulosic substrates. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:20. [PMID: 29422948 PMCID: PMC5787917 DOI: 10.1186/s13068-018-1022-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 01/11/2018] [Indexed: 05/28/2023]
Abstract
BACKGROUND Presently, enzymes still constitute a major part of the cost of biofuel production from lignocellulosic biomass. Processive endoglucanases, which possess both endoglucanase and exoglucanase activity, have the potential to reduce the costs of biomass saccharification when used together with commercial cellulases. Therefore, the exploration of new processive endoglucanases has attracted much attention with a view to accelerating the industrialization of biofuels and biochemicals. RESULTS The endoglucanase EG5C and its truncated form EG5C-1 from Bacillus subtilis BS-5 were expressed and characterized. EG5C was a typical endoglucanase, comprised of a family 5 catalytic domain and family 3 carbohydrate-binding domain, and which had high activity toward soluble cellulosic substrates, but low activity toward insoluble cellulosic substrates. Importantly, the truncated form EG5C-1 was a processive endoglucanase that hydrolyzed not only carboxymethyl cellulose (CMC), but also insoluble cellulosic substrates. The hydrolytic activities of EG5C-1 towards CMC, phosphoric acid-swollen cellulose (PASC), p-nitrophenyl-β-d-cellobioside, filter paper and Avicel are 4170, 700, 2550, 405 and 320 U/μmol, respectively. These data demonstrated that EG5C-1 had higher activity ratio of exoglucanase to endoglucanase than other known processive endoglucanases. When PASC was degraded by EG5C-1, the ratio of soluble to insoluble reducing sugars was about 3.7 after 3 h of incubation with cellobiose and cellotriose as the main products. Importantly, EG5C-1 alone was able to hydrolyze filter paper and PASC. At 5% substrate concentration and 10 FPU/g PASC enzyme loading, the saccharification yield was 76.5% after 60 h of incubation. Replacement of a phenylalanine residue (F238) by an alanine at the entrance/exit of the substrate binding cleft significantly reduces the ability of EG5C-1 to degrade filter paper and Avicel, but this mutation has little impact on CMCase activity. The processivity of this mutant was also greatly reduced while its cellulose binding ability was markedly enhanced. CONCLUSIONS The processive endoglucanase EG5C-1 from B. subtilis BS-5 exhibits excellent properties that render it a suitable candidate for use in biofuel and biochemical production from lignocellulosic biomass. In addition, our studies also provide useful information for research on enzyme processivity at the molecular level.
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Affiliation(s)
- Bin Wu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, 30 Puzhunan road, Nanjing, 211816 Jiangsu China
- China Jiangsu National Synergetic Innovation Center for Advanced Materials, 30 Puzhunan road, Nanjing, 211816 Jiangsu China
| | - Shan Zheng
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, QLD 4072 Australia
| | - Marcelo Monteiro Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, QLD 4072 Australia
| | - Luke W. Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, QLD 4072 Australia
| | - Siyuan Chang
- School of Pharmaceutical Sciences, Nanjing Tech University, 30 Puzhunan road, Nanjing, 211816 Jiangsu China
| | - Bingfang He
- China Jiangsu National Synergetic Innovation Center for Advanced Materials, 30 Puzhunan road, Nanjing, 211816 Jiangsu China
- School of Pharmaceutical Sciences, Nanjing Tech University, 30 Puzhunan road, Nanjing, 211816 Jiangsu China
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, QLD 4072 Australia
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Druzhinina IS, Kubicek CP. Genetic engineering of Trichoderma reesei cellulases and their production. Microb Biotechnol 2017; 10:1485-1499. [PMID: 28557371 PMCID: PMC5658622 DOI: 10.1111/1751-7915.12726] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/11/2017] [Accepted: 04/11/2017] [Indexed: 11/26/2022] Open
Abstract
Lignocellulosic biomass, which mainly consists of cellulose, hemicellulose and lignin, is the most abundant renewable source for production of biofuel and biorefinery products. The industrial use of plant biomass involves mechanical milling or chipping, followed by chemical or physicochemical pretreatment steps to make the material more susceptible to enzymatic hydrolysis. Thereby the cost of enzyme production still presents the major bottleneck, mostly because some of the produced enzymes have low catalytic activity under industrial conditions and/or because the rate of hydrolysis of some enzymes in the secreted enzyme mixture is limiting. Almost all of the lignocellulolytic enzyme cocktails needed for the hydrolysis step are produced by fermentation of the ascomycete Trichoderma reesei (Hypocreales). For this reason, the structure and mechanism of the enzymes involved, the regulation of their expression and the pathways of their formation and secretion have been investigated in T. reesei in considerable details. Several of the findings thereby obtained have been used to improve the formation of the T. reesei cellulases and their properties. In this article, we will review the achievements that have already been made and also show promising fields for further progress.
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Affiliation(s)
- Irina S. Druzhinina
- Microbiology GroupResearch Area Biochemical TechnologyInstitute of Chemical, Environmental and Biological EngineeringTU WienViennaAustria
| | - Christian P. Kubicek
- Microbiology GroupResearch Area Biochemical TechnologyInstitute of Chemical, Environmental and Biological EngineeringTU WienViennaAustria
- Present address:
Steinschötelgasse 7Wien1100Austria
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Physiological and Molecular Understanding of Bacterial Polysaccharide Monooxygenases. Microbiol Mol Biol Rev 2017; 81:81/3/e00015-17. [PMID: 28659491 DOI: 10.1128/mmbr.00015-17] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteria have long been known to secrete enzymes that degrade cellulose and chitin. The degradation of these two polymers predominantly involves two enzyme families that work synergistically with one another: glycoside hydrolases (GHs) and polysaccharide monooxygenases (PMOs). Although bacterial PMOs are a relatively recent addition to the known biopolymer degradation machinery, there is an extensive amount of literature implicating PMO in numerous physiological roles. This review focuses on these diverse and physiological aspects of bacterial PMOs, including facilitating endosymbiosis, conferring a nutritional advantage, and enhancing virulence in pathogenic organisms. We also discuss the correlation between the presence of PMOs and bacterial lifestyle and speculate on the advantages conferred by PMOs under these conditions. In addition, the molecular aspects of bacterial PMOs, as well as the mechanisms regulating PMO expression and the function of additional domains associated with PMOs, are described. We anticipate that increasing research efforts in this field will continue to expand our understanding of the molecular and physiological roles of bacterial PMOs.
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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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Leis B, Held C, Bergkemper F, Dennemarck K, Steinbauer R, Reiter A, Mechelke M, Moerch M, Graubner S, Liebl W, Schwarz WH, Zverlov VV. Comparative characterization of all cellulosomal cellulases from Clostridium thermocellum reveals high diversity in endoglucanase product formation essential for complex activity. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:240. [PMID: 29075324 PMCID: PMC5651568 DOI: 10.1186/s13068-017-0928-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/10/2017] [Indexed: 05/06/2023]
Abstract
BACKGROUND Clostridium thermocellum is a paradigm for efficient cellulose degradation and a promising organism for the production of second generation biofuels. It owes its high degradation rate on cellulosic substrates to the presence of supra-molecular cellulase complexes, cellulosomes, which comprise over 70 different single enzymes assembled on protein-backbone molecules of the scaffold protein CipA. RESULTS Although all 24 single-cellulosomal cellulases were described previously, we present the first comparative catalogue of all these enzymes together with a comprehensive analysis under identical experimental conditions, including enzyme activity, binding characteristics, substrate specificity, and product analysis. In the course of our study, we encountered four types of distinct enzymatic hydrolysis modes denoted by substrate specificity and hydrolysis product formation: (i) exo-mode cellobiohydrolases (CBH), (ii) endo-mode cellulases with no specific hydrolysis pattern, endoglucanases (EG), (iii) processive endoglucanases with cellotetraose as intermediate product (pEG4), and (iv) processive endoglucanases with cellobiose as the main product (pEG2). These modes are shown on amorphous cellulose and on model cello-oligosaccharides (with degree of polymerization DP 3 to 6). Artificial mini-cellulosomes carrying combinations of cellulases showed their highest activity when all four endoglucanase-groups were incorporated into a single complex. Such a modeled nonavalent complex (n = 9 enzymes bound to the recombinant scaffolding protein CipA) reached half of the activity of the native cellulosome. Comparative analysis of the protein architecture and structure revealed characteristics that play a role in product formation and enzyme processivity. CONCLUSIONS The identification of a new endoglucanase type expands the list of known cellulase functions present in the cellulosome. Our study shows that the variety of processivities in the enzyme complex is a key enabler of its high cellulolytic efficiency. The observed synergistic effect may pave the way for a better understanding of the enzymatic interactions and the design of more active lignocellulose-degrading cellulase cocktails in the future.
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Affiliation(s)
- Benedikt Leis
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Claudia Held
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Fabian Bergkemper
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Katharina Dennemarck
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Robert Steinbauer
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Alarich Reiter
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Matthias Mechelke
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Matthias Moerch
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Sigrid Graubner
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Wolfgang Liebl
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Wolfgang H. Schwarz
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Vladimir V. Zverlov
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, 85354 Freising, Germany
- Institute of Molecular Genetics, Russian Academy of Science, Kurchatov Sq. 2, Moscow, 123182 Russia
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Kari J, Kont R, Borch K, Buskov S, Olsen JP, Cruyz-Bagger N, Väljamäe P, Westh P. Anomeric Selectivity and Product Profile of a Processive Cellulase. Biochemistry 2016; 56:167-178. [PMID: 28026938 DOI: 10.1021/acs.biochem.6b00636] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cellobiohydrolases (CBHs) make up an important group of enzymes for both natural carbon cycling and industrial deconstruction of lignocellulosic biomass. The consecutive hydrolysis of one cellulose strand relies on an intricate pattern of enzyme-substrate interactions in the long, tunnel-shaped binding site of the CBH. In this work, we have investigated the initial complexation mode with cellulose of the most thoroughly studied CBH, Cel7A from Hypocrea jecorina (HjCel7A). We found that HjCel7A predominantly produces glucose when it initiates a processive run on insoluble microcrystalline cellulose, confirming the validity of an even and odd product ratio as an estimate of processivity. Moreover, the glucose released from cellulose was predominantly α-glucose. A link between the initial binding mode of the enzyme and the reducing end configuration was investigated by inhibition studies with the two anomers of cellobiose. A clear preference for β-cellobiose in product binding site +2 was observed for HjCel7A, but not the homologous endoglucanase, HjCe7B. Possible relationships between this anomeric preference in the product site and the prevalence of odd-numbered initial-cut products are discussed, and a correlation between processivity and anomer selectivity is proposed.
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Affiliation(s)
- Jeppe Kari
- Research Unit for Functional Biomaterials, Roskilde University , Roskilde, Denmark
| | - Riin Kont
- Institute of Molecular and Cell Biology, University of Tartu , Tartu, Estonia
| | - Kim Borch
- Novozymes A/S , Krogshøjvej 36, DK-2880 Bagsværd, Denmark
| | - Steen Buskov
- Novozymes A/S , Krogshøjvej 36, DK-2880 Bagsværd, Denmark
| | - Johan Pelck Olsen
- Research Unit for Functional Biomaterials, Roskilde University , Roskilde, Denmark
| | | | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu , Tartu, Estonia
| | - Peter Westh
- Research Unit for Functional Biomaterials, Roskilde University , Roskilde, Denmark
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Sobhanifar S, Worrall LJ, King DT, Wasney GA, Baumann L, Gale RT, Nosella M, Brown ED, Withers SG, Strynadka NCJ. Structure and Mechanism of Staphylococcus aureus TarS, the Wall Teichoic Acid β-glycosyltransferase Involved in Methicillin Resistance. PLoS Pathog 2016; 12:e1006067. [PMID: 27973583 PMCID: PMC5156392 DOI: 10.1371/journal.ppat.1006067] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/15/2016] [Indexed: 01/05/2023] Open
Abstract
In recent years, there has been a growing interest in teichoic acids as targets for antibiotic drug design against major clinical pathogens such as Staphylococcus aureus, reflecting the disquieting increase in antibiotic resistance and the historical success of bacterial cell wall components as drug targets. It is now becoming clear that β-O-GlcNAcylation of S. aureus wall teichoic acids plays a major role in both pathogenicity and antibiotic resistance. Here we present the first structure of S. aureus TarS, the enzyme responsible for polyribitol phosphate β-O-GlcNAcylation. Using a divide and conquer strategy, we obtained crystal structures of various TarS constructs, mapping high resolution overlapping N-terminal and C-terminal structures onto a lower resolution full-length structure that resulted in a high resolution view of the entire enzyme. Using the N-terminal structure that encapsulates the catalytic domain, we furthermore captured several snapshots of TarS, including the native structure, the UDP-GlcNAc donor complex, and the UDP product complex. These structures along with structure-guided mutants allowed us to elucidate various catalytic features and identify key active site residues and catalytic loop rearrangements that provide a valuable platform for anti-MRSA drug design. We furthermore observed for the first time the presence of a trimerization domain composed of stacked carbohydrate binding modules, commonly observed in starch active enzymes, but adapted here for a poly sugar-phosphate glycosyltransferase. Historically, β-lactam class antibiotics such as methicillin have been very successful in the treatment of bacterial infections, effectively destroying bacteria by rupturing their cell walls while posing little harm to the human organism. In recent years, however, the alarming emergence of Methicillin Resistant S. aureus or MRSA has resulted in a world-wide health crisis, calling on new strategies to combat pathogenesis and antibiotic resistance. As such, understanding the pathways and players that orchestrate resistance is important for overcoming these mechanisms and restoring our powerful β-lactam antibiotic arsenal. In this article we describe the crystal structure of TarS, an enzyme responsible for the glycosylation of wall teichoic acid polymers of the S. aureus cell wall, a process that has been shown to be specifically responsible for methicillin resistance in MRSA. TarS is therefore a promising drug target whose inhibition in combinational therapies would result in MRSA re-sensitization to β-lactam antibiotics. Here we present the first structure of TarS together with several snap-shots of its substrate/product complexes, and elucidate important catalytic features that are valuable for rational drug design efforts to combat resistance in MRSA.
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Affiliation(s)
- Solmaz Sobhanifar
- Department of Biochemistry and Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - Liam J. Worrall
- Department of Biochemistry and Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dustin T. King
- Department of Biochemistry and Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gregory A. Wasney
- Department of Biochemistry and Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - Lars Baumann
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert T. Gale
- Department of Chemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Michael Nosella
- Department of Biochemistry and Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eric D. Brown
- Department of Chemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Stephen G. Withers
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Natalie C. J. Strynadka
- Department of Biochemistry and Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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Kubicek CP, Kubicek EM. Enzymatic deconstruction of plant biomass by fungal enzymes. Curr Opin Chem Biol 2016; 35:51-57. [DOI: 10.1016/j.cbpa.2016.08.028] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 08/25/2016] [Accepted: 08/26/2016] [Indexed: 10/21/2022]
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47
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Hasunuma T, Kondo A. Production of Fuels and Chemicals from Biomass by Integrated Bioprocesses. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807833.ch5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Tomohisa Hasunuma
- Kobe University; Graduate School of Science, Technology and Innovation; 1-1 Rokkodai Nada Kobe 657-8501 Japan
| | - Akihiko Kondo
- RIKEN; Biomass Engineering Program; 1-7-22 Suehiro-cho, Tsurumi Yokohama 230-0045 Japan
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48
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Crystal structures of wild‐type
Trichoderma reesei
Cel7A catalytic domain in open and closed states. FEBS Lett 2016; 590:4429-4438. [DOI: 10.1002/1873-3468.12464] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/03/2016] [Accepted: 10/10/2016] [Indexed: 11/07/2022]
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Abstract
Complex carbohydrates are ubiquitous in all kingdoms of life. As major components of the plant cell wall they constitute both a rich renewable carbon source for biotechnological transformation into fuels, chemicals and materials, and also form an important energy source as part of a healthy human diet. In both contexts, there has been significant, sustained interest in understanding how microbes transform these substrates. Classical perspectives of microbial polysaccharide degradation are currently being augmented by recent advances in the discovery of lytic polysaccharide monooxygenases (LPMOs) and polysaccharide utilization loci (PULs). Fundamental discoveries in carbohydrate enzymology are both advancing biological understanding, as well as informing applications in industrial biomass conversion and modulation of the human gut microbiota to mediate health benefits.
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50
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Kont R, Kari J, Borch K, Westh P, Väljamäe P. Inter-domain Synergism Is Required for Efficient Feeding of Cellulose Chain into Active Site of Cellobiohydrolase Cel7A. J Biol Chem 2016; 291:26013-26023. [PMID: 27780868 DOI: 10.1074/jbc.m116.756007] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/21/2016] [Indexed: 01/27/2023] Open
Abstract
Structural polysaccharides like cellulose and chitin are abundant and their enzymatic degradation to soluble sugars is an important route in green chemistry. Processive glycoside hydrolases (GHs), like cellobiohydrolase Cel7A of Trichoderma reesei (TrCel7A) are key components of efficient enzyme systems. TrCel7A consists of a catalytic domain (CD) and a smaller carbohydrate-binding module (CBM) connected through the glycosylated linker peptide. A tunnel-shaped active site rests in the CD and contains 10 glucose unit binding sites. The active site of TrCel7A is lined with four Trp residues with two of them, Trp-40 and Trp-38, in the substrate binding sites near the tunnel entrance. Although addressed in numerous studies the elucidation of the role of CBM and active site aromatics has been obscured by a complex multistep mechanism of processive GHs. Here we studied the role of the CBM-linker and Trp-38 of TrCel7A with respect to binding affinity, on- and off-rates, processivity, and synergism with endoglucanase. The CBM-linker increased the on-rate and substrate affinity of the enzyme. The Trp-38 to Ala substitution resulted in increased off-rates and decreased processivity. The effect of the Trp-38 to Ala substitution on on-rates was strongly dependent on the presence of the CBM-linker. This compensation between CBM-linker and Trp-38 indicates synergism between CBM-linker and CD in feeding the cellulose chain into the active site. The inter-domain synergism was pre-requisite for the efficient degradation of cellulose in the presence of endoglucanase.
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Affiliation(s)
- Riin Kont
- From the Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia
| | - Jeppe Kari
- the Department of Science and Environment, Roskilde University, DK-4000 Roskilde, Denmark, and
| | - Kim Borch
- Novozymes A/S, Bagsværd DK-2880, Denmark
| | - Peter Westh
- the Department of Science and Environment, Roskilde University, DK-4000 Roskilde, Denmark, and
| | - Priit Väljamäe
- From the Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia,
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