1
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Feng X, Yao Y, Xu N, Jia H, Li X, Zhao J, Chen S, Qu Y. Pretreatment Affects Profits From Xylanase During Enzymatic Saccharification of Corn Stover Through Changing the Interaction Between Lignin and Xylanase Protein. Front Microbiol 2022; 12:754593. [PMID: 35002999 PMCID: PMC8739958 DOI: 10.3389/fmicb.2021.754593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/20/2021] [Indexed: 11/27/2022] Open
Abstract
Effective pretreatment is vital to improve the biomass conversion efficiency, which often requires the addition of xylanase as an accessory enzyme to enhance enzymatic saccharification of corn stover. In this study, we investigated the effect of two sophisticated pretreatment methods including ammonium sulfite (AS) and steam explosion (SE) on the xylanase profits involved in enzymatic hydrolysis of corn stover. We further explored the interactions between lignin and xylanase Xyn10A protein. Our results showed that the conversion rates of glucan and xylan in corn stover by AS pretreatment were higher by Xyn10A supplementation than that by SE pretreatment. Compared with the lignin from SE pretreated corn stover, the lignin from AS pretreated corn stover had a lower Xyn10A initial adsorption velocity (13.56 vs. 10.89 mg g−1 min−1) and adsorption capacity (49.46 vs. 27.42 mg g−1 of lignin) and weakened binding strength (310.6 vs. 215.9 L g−1). Our study demonstrated the low absolute zeta potential and strong hydrophilicity of the lignin may partly account for relative weak interaction between xylanase protein and lignin from AS pretreated corn stover. In conclusion, our results suggested that AS pretreatment weakened the inhibition of lignin to enzyme, promoted the enzymatic hydrolysis of corn stover, and decreased the cost of enzyme in bioconversion.
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Affiliation(s)
- Xiaoting Feng
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yini Yao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Nuo Xu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Hexue Jia
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xuezhi Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Jian Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Shicheng Chen
- Department of Clinical and Diagnostic Sciences, School of Health Sciences, Oakland University, Rochester, MI, United States
| | - Yinbo Qu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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2
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Anuganti M, Fu H, Ekatan S, Kumar CV, Lin Y. Kinetic Study on Enzymatic Hydrolysis of Cellulose in an Open, Inhibition-Free System. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:5180-5192. [PMID: 33872034 DOI: 10.1021/acs.langmuir.1c00115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Due to the complexity of cellulases and the requirement of enzyme adsorption on cellulose prior to reactions, it is difficult to evaluate their reaction with a general mechanistic scheme. Nevertheless, it is of great interest to come up with an approximate analytic description of a valid model for the purpose of developing an intuitive understanding of these complex enzyme systems. Herein, we used the surface plasmonic resonance method to monitor the action of a cellobiohydrolase by itself, as well as its mixture with a synergetic endoglucanase, on the surface of a regenerated model cellulose film, under continuous flow conditions. We found a phenomenological approach by taking advantage of the long steady state of cellulose hydrolysis in the open, inhibition-free system. This provided a direct and reliable way to analyze the adsorption and reaction processes with a minimum number of fitting parameters. We investigated a generalized Langmuir-Michaelis-Menten model to describe a full set of kinetic results across a range of enzyme concentrations, compositions, and temperatures. The overall form of the equations describing the pseudo-steady-state kinetics of the flow-system shares some interesting similarities with the Michaelis-Menten equation. The use of familiar Michaelis-Menten parameters in the analysis provides a unifying framework to study cellulase kinetics. The strategy may provide a shortcut for approaching a quantitative while intuitive understanding of enzymatic degradation of cellulose from top to bottom. The open system approach and the kinetic analysis should be applicable to a variety of cellulases and reaction systems to accelerate the progress in the field.
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Affiliation(s)
- Murali Anuganti
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Hailin Fu
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Stephen Ekatan
- Polymer Program, Institute of Material Sciences, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Challa V Kumar
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Yao Lin
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
- Polymer Program, Institute of Material Sciences, University of Connecticut, Storrs, Connecticut 06269, United States
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3
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Ezaki T, Nishinari K, Samejima M, Igarashi K. Bridging the Micro-Macro Gap between Single-Molecular Behavior and Bulk Hydrolysis Properties of Cellulase. PHYSICAL REVIEW LETTERS 2019; 122:098102. [PMID: 30932525 DOI: 10.1103/physrevlett.122.098102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/07/2018] [Indexed: 06/09/2023]
Abstract
The microscopic kinetics of enzymes at the single-molecule level often deviate considerably from those expected from bulk biochemical experiments. Here, we propose a coarse-grained-model approach to bridge this gap, focusing on the unexpectedly slow bulk hydrolysis of crystalline cellulose by cellulase, which constitutes a major obstacle to mass production of biofuels and biochemicals. Building on our previous success in tracking the movements of single molecules of cellulase on crystalline cellulose, we develop a mathematical description of the collective motion and function of enzyme molecules hydrolyzing the surface of cellulose. Model simulations robustly explained the experimental findings at both the microscopic and macroscopic levels and revealed a hitherto-unknown mechanism causing a considerable slowdown of the reaction, which we call the crowding-out effect. The size of the cellulase molecule impacted significantly on the collective dynamics, whereas the rate of molecular motion on the surface did not.
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Affiliation(s)
- Takahiro Ezaki
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Katsuhiro Nishinari
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Masahiro Samejima
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kiyohiko Igarashi
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
- VTT Technical Research Centre of Finland, Tietotie 2, Espoo FI-02044, Finland
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4
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Lu X, Feng X, Li X, Zhao J. The adsorption properties of endoglucanase to lignin and their impact on hydrolysis. BIORESOURCE TECHNOLOGY 2018; 267:110-116. [PMID: 30014989 DOI: 10.1016/j.biortech.2018.06.031] [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: 04/28/2018] [Revised: 06/10/2018] [Accepted: 06/12/2018] [Indexed: 06/08/2023]
Abstract
Nonproductive adsorption of cellulase to lignin dramatically influenced the hydrolysis efficiency of lignocellulose. By comparing the adsorption behaviors of CBH and EG, we found that the adsorption of EG to lignin showed lower adsorption velocity and capacity versus CBH. During the adsorption of EG to lignin, carbohydrate binding domain (CBM) and catalytic domain (CD) both played an important role by a two-step adsorption process, in which CD slowly bond on lignin and developed stronger interaction with lignin. The optimal binding position of EG on lignin was consistent with that on polysaccharide located in the open catalytic tunnel. So, the adsorption of EG to lignin not only limited the movement of enzyme, but also restricted the catalytic ability of enzyme, which dramatically influenced enzymatic hydrolysis. Increasing the proportion of EG in cellulase cocktails or engineering "weak lignin adsorbed" EG was necessary to relieve the influence of lignin adsorption on hydrolysis.
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Affiliation(s)
- Xianqin Lu
- State Key Laboratory of Microbial Technology, Shandong University, No. 72, Binhai Road, Qingdao 266237, PR China
| | - Xiaoting Feng
- State Key Laboratory of Microbial Technology, Shandong University, No. 72, Binhai Road, Qingdao 266237, PR China
| | - Xuezhi Li
- State Key Laboratory of Microbial Technology, Shandong University, No. 72, Binhai Road, Qingdao 266237, PR China
| | - Jian Zhao
- State Key Laboratory of Microbial Technology, Shandong University, No. 72, Binhai Road, Qingdao 266237, PR China.
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5
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Lu X, Wang C, Li X, Zhao J. Temperature and pH influence adsorption of cellobiohydrolase onto lignin by changing the protein properties. BIORESOURCE TECHNOLOGY 2017; 245:819-825. [PMID: 28926914 DOI: 10.1016/j.biortech.2017.08.139] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/21/2017] [Accepted: 08/22/2017] [Indexed: 05/03/2023]
Abstract
Non-productive adsorption of cellulase onto lignin restricted the movement of cellulase and also hindered the cellulase recycling in bioconversion of lignocellulose. In this study, effect of temperature and pH on adsorption and desorption of cellobiohydrolase (CBH) on lignin and its possible mechanism were discussed. It found that pH value and temperature influenced the adsorption and desorption behaviors of CBH on lignin. Different thermodynamic models suggested that the action between lignin and CBH was physical action. More CBH was adsorbed onto lignin, but lower initial adsorption velocity was detected at 50°C comparing with 4°C. Elevating pH value could improve desorption of cellulase from lignin. The changes of hydrophobicity and electric potential on protein surface may partially explain the impact of environmental conditions on the adsorption and desorption behaviors of CBH on lignin, and comparing to electrical interaction, the hydrophobicity may be the dominating factor influencing the behaviors.
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Affiliation(s)
- Xianqin Lu
- State Key Laboratory of Microbial Technology, Shandong University, Jinan City, Shandong Province 250100, China
| | - Can Wang
- State Key Laboratory of Microbial Technology, Shandong University, Jinan City, Shandong Province 250100, China
| | - Xuezhi Li
- State Key Laboratory of Microbial Technology, Shandong University, Jinan City, Shandong Province 250100, China
| | - Jian Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Jinan City, Shandong Province 250100, China.
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6
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Kansou K, Rémond C, Paës G, Bonnin E, Tayeb J, Bredeweg B. Testing scientific models using Qualitative Reasoning: Application to cellulose hydrolysis. Sci Rep 2017; 7:14122. [PMID: 29074872 PMCID: PMC5658447 DOI: 10.1038/s41598-017-14281-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 10/06/2017] [Indexed: 12/17/2022] Open
Abstract
With the accumulation of scientific information in natural science, even experts can find difficult to keep integrating new piece of information. It is critical to explore modelling solutions able to capture information scattered in publications as a computable representation form. Traditional modelling techniques are important in that regard, but relying on numerical information comes with limitations for integrating results from distinct studies, high-level representations can be more suited. We present an approach to stepwise construct mechanistic explanation from selected scientific papers using the Qualitative Reasoning framework. As a proof of concept, we apply the approach to modelling papers about cellulose hydrolysis mechanism, focusing on the causal explanations for the decreasing of hydrolytic rate. Two explanatory QR models are built to capture classical explanations for the phenomenon. Our results show that none of them provides sufficient explanation for a set of basic experimental observations described in the literature. Combining the two explanations into a third one allowed to get a new and sufficient explanation for the experimental results. In domains where numerical data are scarce and strongly related to the experimental conditions, this approach can aid assessing the conceptual validity of an explanation and support integration of knowledge from different sources.
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Affiliation(s)
- Kamal Kansou
- INRA, Biopolymères Interactions Assemblages, BP 71267, 44316, Nantes, France.
| | - Caroline Rémond
- FARE laboratory, INRA, University of Reims Champagne-Ardenne, 51100, Reims, France
| | - Gabriel Paës
- FARE laboratory, INRA, University of Reims Champagne-Ardenne, 51100, Reims, France
| | - Estelle Bonnin
- INRA, Biopolymères Interactions Assemblages, BP 71267, 44316, Nantes, France
| | - Jean Tayeb
- FARE laboratory, INRA, University of Reims Champagne-Ardenne, 51100, Reims, France
| | - Bert Bredeweg
- Informatics Institute, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
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7
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Shi J, Wu D, Zhang L, Simmons BA, Singh S, Yang B, Wyman CE. Dynamic changes of substrate reactivity and enzyme adsorption on partially hydrolyzed cellulose. Biotechnol Bioeng 2016; 114:503-515. [PMID: 27617791 DOI: 10.1002/bit.26180] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/29/2016] [Accepted: 09/05/2016] [Indexed: 11/10/2022]
Abstract
The enzymatic hydrolysis of cellulose is a thermodynamically challenging catalytic process that is influenced by both substrate-related and enzyme-related factors. In this study, a proteolysis approach was applied to recover and clean the partially converted cellulose at the different stages of enzymatic hydrolysis to monitor the hydrolysis rate as a function of substrate reactivity/accessibility and investigate surface characteristics of the partially converted cellulose. Enzyme-substrate interactions between individual key cellulase components from wild-type Trichoderma reesei and partially converted cellulose were followed and correlated to the enzyme adsorption capacity and dynamic sugar release. Results suggest that cellobiohydrolase CBH1 (Cel7A) and endoglucanases EG2 (Cel5A) adsorption capacities decreased as cellulose was progressively hydrolyzed, likely due to the "depletion" of binding sites. Furthermore, the degree of synergism between CBH1 and EG2 varied depending on the enzyme loading and the substrates. The results provide a better understanding of the relationship between dynamic change of substrate features and the functionality of various cellulase components during enzymatic hydrolysis. Biotechnol. Bioeng. 2017;114: 503-515. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Jian Shi
- Center for Environmental Research and Technology, University of California, 1084 Columbia Avenue, Riverside, CA 92507.,Deconstruction Division, Joint BioEnergy Institute, Emeryville, California.,Department of Biosystems and Agricultural Engineering, University of Kentucky, Lexington, Kentucky
| | - Dong Wu
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, California.,Biological and Materials Science Center, Sandia National Laboratories, Livermore, California
| | - Libing Zhang
- Bioproducts, Sciences and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, Washington
| | - Blake A Simmons
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, California
| | - Seema Singh
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, California.,Biological and Materials Science Center, Sandia National Laboratories, Livermore, California
| | - Bin Yang
- Center for Environmental Research and Technology, University of California, 1084 Columbia Avenue, Riverside, CA 92507.,Bioproducts, Sciences and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, Washington
| | - Charles E Wyman
- Center for Environmental Research and Technology, University of California, 1084 Columbia Avenue, Riverside, CA 92507.,Department of Chemical and Environmental Engineering, Bourns College of Engineering, Riverside, California.,BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee
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8
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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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9
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Nakamura A, Tasaki T, Ishiwata D, Yamamoto M, Okuni Y, Visootsat A, Maximilien M, Noji H, Uchiyama T, Samejima M, Igarashi K, Iino R. Single-molecule Imaging Analysis of Binding, Processive Movement, and Dissociation of Cellobiohydrolase Trichoderma reesei Cel6A and Its Domains on Crystalline Cellulose. J Biol Chem 2016; 291:22404-22413. [PMID: 27609516 DOI: 10.1074/jbc.m116.752048] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 08/24/2016] [Indexed: 11/06/2022] Open
Abstract
Trichoderma reesei Cel6A (TrCel6A) is a cellobiohydrolase that hydrolyzes crystalline cellulose into cellobiose. Here we directly observed the reaction cycle (binding, surface movement, and dissociation) of single-molecule intact TrCel6A, isolated catalytic domain (CD), cellulose-binding module (CBM), and CBM and linker (CBM-linker) on crystalline cellulose Iα The CBM-linker showed a binding rate constant almost half that of intact TrCel6A, whereas those of the CD and CBM were only one-tenth of intact TrCel6A. These results indicate that the glycosylated linker region largely contributes to initial binding on crystalline cellulose. After binding, all samples showed slow and fast dissociations, likely caused by the two different bound states due to the heterogeneity of cellulose surface. The CBM showed much higher specificity to the high affinity site than to the low affinity site, whereas the CD did not, suggesting that the CBM leads the CD to the hydrophobic surface of crystalline cellulose. On the cellulose surface, intact molecules showed slow processive movements (8.8 ± 5.5 nm/s) and fast diffusional movements (30-40 nm/s), whereas the CBM-Linker, CD, and a catalytically inactive full-length mutant showed only fast diffusional movements. These results suggest that both direct binding and surface diffusion contribute to searching of the hydrolysable point of cellulose chains. The duration time constant for the processive movement was 7.7 s, and processivity was estimated as 68 ± 42. Our results reveal the role of each domain in the elementary steps of the reaction cycle and provide the first direct evidence of the processive movement of TrCel6A on crystalline cellulose.
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Affiliation(s)
- Akihiko Nakamura
- From the Okazaki Institute for Integrative Bioscience and.,the Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Kanagawa 240-0193, Japan
| | - Tomoyuki Tasaki
- the Department of Applied Chemistry, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Daiki Ishiwata
- From the Okazaki Institute for Integrative Bioscience and
| | | | - Yasuko Okuni
- From the Okazaki Institute for Integrative Bioscience and
| | - Akasit Visootsat
- the Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Morice Maximilien
- the National Chemical Engineering Institute in Paris, Paris 75005, France
| | - Hiroyuki Noji
- the Department of Applied Chemistry, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Taku Uchiyama
- the Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan, and
| | - Masahiro Samejima
- the Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan, and
| | - Kiyohiko Igarashi
- the Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan, and.,the VTT Technical Research Centre of Finland, Espoo FI-02044 VTT, Finland
| | - Ryota Iino
- From the Okazaki Institute for Integrative Bioscience and .,the Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Kanagawa 240-0193, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, Aichi 444-8787, Japan
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10
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Treebupachatsakul T, Shioya K, Nakazawa H, Kawaguchi T, Morikawa Y, Shida Y, Ogasawara W, Okada H. Utilization of recombinant Trichoderma reesei expressing Aspergillus aculeatus β-glucosidase I (JN11) for a more economical production of ethanol from lignocellulosic biomass. J Biosci Bioeng 2015; 120:657-65. [DOI: 10.1016/j.jbiosc.2015.04.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/07/2015] [Accepted: 04/22/2015] [Indexed: 10/23/2022]
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11
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Happs RM, Guan X, Resch MG, Davis MF, Beckham GT, Tan Z, Crowley MF. O-glycosylation effects on family 1 carbohydrate-binding module solution structures. FEBS J 2015; 282:4341-56. [PMID: 26307003 DOI: 10.1111/febs.13500] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/18/2015] [Accepted: 08/21/2015] [Indexed: 01/20/2023]
Abstract
UNLABELLED Family 1 carbohydrate-binding modules (CBMs) are ubiquitous components of multimodular fungal enzymes that degrade plant cell wall polysaccharides and bind specifically to cellulose. Native glycosylation of family 1 CBMs has been shown to substantially impact multiple physical properties, including thermal and proteolytic stability and cellulose binding affinity. To gain molecular insights into the changes in CBM properties upon glycosylation, solution structures of two glycoforms of a Trichoderma reesei family 1 CBM were studied by NMR spectroscopy: a glycosylated family 1 CBM with a mannose group attached to both Thr1 and Ser3 and a second family 1 CBM with single mannose groups attached to Thr1, Ser3 and Ser14. The structures clearly reveal that monosaccharides at both Ser3 and Ser14 on family 1 CBMs present additional cellulose binding platforms, similar to well-characterized aromatic residues at the binding interface, which align to the cellulose surface. These results are in agreement with previous experimental work demonstrating that glycans at Ser3 and Ser14 impart significant improvements in binding affinity. Additionally, detailed analysis of the NMR structures and molecular simulations indicates that the protein backbone of the CBM is not significantly altered by attachment of monosaccharides, and that the mannose attached to Ser14 may be more flexible than the mannose at Ser3. Overall, the present study reveals how family 1 CBM structures are affected by covalent attachment of monosaccharides, which are likely important post-translational modifications of these common subdomains of fungal plant cell wall degrading enzymes. DATABASE Structural data have been deposited in the RCSB Protein Data Bank (PDB codes: 2MWJ and 2MWK) and the BioMagRes Bank (BMRB codes: 25331 and 25332) for CBM_M2 and CBM_M3, respectively.
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Affiliation(s)
- Renee M Happs
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO, USA
| | - Xiaoyang Guan
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Michael G Resch
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO, USA
| | - Mark F Davis
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO, USA
| | - Gregg T Beckham
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO, USA
| | - Zhongping Tan
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Michael F Crowley
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO, USA
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12
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Payne CM, Knott BC, Mayes HB, Hansson H, Himmel ME, Sandgren M, Ståhlberg J, Beckham GT. Fungal Cellulases. Chem Rev 2015; 115:1308-448. [DOI: 10.1021/cr500351c] [Citation(s) in RCA: 533] [Impact Index Per Article: 59.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Christina M. Payne
- Department
of Chemical and Materials Engineering and Center for Computational
Sciences, University of Kentucky, 177 F. Paul Anderson Tower, Lexington, Kentucky 40506, United States
| | - Brandon C. Knott
- National
Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
| | - Heather B. Mayes
- Department
of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Henrik Hansson
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Michael E. Himmel
- Biosciences
Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Mats Sandgren
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Jerry Ståhlberg
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Gregg T. Beckham
- National
Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
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13
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Greene ER, Himmel ME, Beckham GT, Tan Z. Glycosylation of Cellulases: Engineering Better Enzymes for Biofuels. Adv Carbohydr Chem Biochem 2015; 72:63-112. [PMID: 26613815 DOI: 10.1016/bs.accb.2015.08.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Cellulose in plant cell walls is the largest reservoir of renewable carbon on Earth. The saccharification of cellulose from plant biomass into soluble sugars can be achieved using fungal and bacterial cellulolytic enzymes, cellulases, and further converted into fuels and chemicals. Most fungal cellulases are both N- and O-glycosylated in their native form, yet the consequences of glycosylation on activity and structure are not fully understood. Studying protein glycosylation is challenging as glycans are extremely heterogeneous, stereochemically complex, and glycosylation is not under direct genetic control. Despite these limitations, many studies have begun to unveil the role of cellulase glycosylation, especially in the industrially relevant cellobiohydrolase from Trichoderma reesei, Cel7A. Glycosylation confers many beneficial properties to cellulases including enhanced activity, thermal and proteolytic stability, and structural stabilization. However, glycosylation must be controlled carefully as such positive effects can be dampened or reversed. Encouragingly, methods for the manipulation of glycan structures have been recently reported that employ genetic tuning of glycan-active enzymes expressed from homogeneous and heterologous fungal hosts. Taken together, these studies have enabled new strategies for the exploitation of protein glycosylation for the production of enhanced cellulases for biofuel production.
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Jalak J, Väljamäe P. Multi-mode binding of Cellobiohydrolase Cel7A from Trichoderma reesei to cellulose. PLoS One 2014; 9:e108181. [PMID: 25265511 PMCID: PMC4180464 DOI: 10.1371/journal.pone.0108181] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 08/19/2014] [Indexed: 01/26/2023] Open
Abstract
Enzymatic hydrolysis of recalcitrant polysaccharides like cellulose takes place on the solid-liquid interface. Therefore the adsorption of enzymes to the solid surface is a pre-requisite for catalysis. Here we used enzymatic activity measurements with fluorescent model-substrate 4-methyl-umbelliferyl-β-D-lactoside for sensitive monitoring of the binding of cellobiohydrolase TrCel7A from Trichoderma reesei to bacterial cellulose (BC). The binding at low nanomolar free TrCel7A concentrations was exclusively active site mediated and was consistent with Langmuir's one binding site model with Kd and Amax values of 2.9 nM and 126 nmol/g BC, respectively. This is the strongest binding observed with non-complexed cellulases and apparently represents the productive binding of TrCel7A to cellulose chain ends on the hydrophobic face of BC microfibril. With increasing free TrCel7A concentrations the isotherm gradually deviated from the Langmuir's one binding site model. This was caused by the increasing contribution of lower affinity binding modes that included both active site mediated binding and non-productive binding with active site free from cellulose chain. The binding of TrCel7A to BC was found to be only partially reversible. Furthermore, the isotherm was dependent on the concentration of BC with more efficient binding observed at lower BC concentrations. The phenomenon can be ascribed to the BC concentration dependent aggregation of BC microfibrils with concomitant reduction of specific surface area.
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Affiliation(s)
- Jürgen Jalak
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- * E-mail:
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Cellulosomal carbohydrate-binding module fromClostridium josuibinds to crystalline and non-crystalline cellulose, and soluble polysaccharides. FEBS Lett 2014; 588:3886-90. [DOI: 10.1016/j.febslet.2014.08.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 08/22/2014] [Accepted: 08/28/2014] [Indexed: 11/30/2022]
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Specificity of O-glycosylation in enhancing the stability and cellulose binding affinity of Family 1 carbohydrate-binding modules. Proc Natl Acad Sci U S A 2014; 111:7612-7. [PMID: 24821760 DOI: 10.1073/pnas.1402518111] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The majority of biological turnover of lignocellulosic biomass in nature is conducted by fungi, which commonly use Family 1 carbohydrate-binding modules (CBMs) for targeting enzymes to cellulose. Family 1 CBMs are glycosylated, but the effects of glycosylation on CBM function remain unknown. Here, the effects of O-mannosylation are examined on the Family 1 CBM from the Trichoderma reesei Family 7 cellobiohydrolase at three glycosylation sites. To enable this work, a procedure to synthesize glycosylated Family 1 CBMs was developed. Subsequently, a library of 20 CBMs was synthesized with mono-, di-, or trisaccharides at each site for comparison of binding affinity, proteolytic stability, and thermostability. The results show that, although CBM mannosylation does not induce major conformational changes, it can increase the thermolysin cleavage resistance up to 50-fold depending on the number of mannose units on the CBM and the attachment site. O-Mannosylation also increases the thermostability of CBM glycoforms up to 16 °C, and a mannose disaccharide at Ser3 seems to have the largest themostabilizing effect. Interestingly, the glycoforms with small glycans at each site displayed higher binding affinities for crystalline cellulose, and the glycoform with a single mannose at each of three positions conferred the highest affinity enhancement of 7.4-fold. Overall, by combining chemical glycoprotein synthesis and functional studies, we show that specific glycosylation events confer multiple beneficial properties on Family 1 CBMs.
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Mello BL, Polikarpov I. Family 1 carbohydrate binding-modules enhance saccharification rates. AMB Express 2014; 4:36. [PMID: 24949270 PMCID: PMC4052752 DOI: 10.1186/s13568-014-0036-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/16/2014] [Indexed: 11/10/2022] Open
Abstract
Cellulose degrading enzymes usually have a two-domain structure consisting of a catalytic domain and a non-catalytic carbohydrate-binding module. Although it is well known the importance of those modules in cell wall degrading process, their function is not yet fully understood. Here, we analyze the cellulose-hydrolysis activity enhancement promoted by the cellobiohydrolase I carbohydrate-binding module from Trichoderma harzianum. It was cloned, expressed, purified and used in combination with either a commercial cellulase preparation, T. reesei cellobiohydrolase I or its separate catalytic domain to hydrolyze filter paper. In all cases the amount of glucose released was increased, reaching up to 30% gain when the carbohydrate-binding module was added to the reaction. We also show that this effect seems to be mediated by a decrease in the recalcitrance of the cellulosic substrate. This effect was observed both for crystalline cellulose samples which underwent incubation with the CBM prior to application of cellulases and for the ones incubated simultaneously. Our studies demonstrate that family 1 carbohydrate-binding modules are able to potentiate the enzymatic degradation of the polysaccharides and their application might contribute to diminishing the currently prohibitive costs of the lignocellulose saccharification process.
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Kamat RK, Ma W, Yang Y, Zhang Y, Wang C, Kumar CV, Lin Y. Adsorption and hydrolytic activity of the polycatalytic cellulase nanocomplex on cellulose. ACS APPLIED MATERIALS & INTERFACES 2013; 5:8486-8494. [PMID: 23968137 DOI: 10.1021/am401916k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The formation of polycatalytic enzyme complexes may enhance the effectiveness of enzymes due to improved substrate interaction and synergistic actions of multiple enzymes in proximity. Much effort has been made to develop highly efficient polycatalytic cellulase complexes by immobilizing cellulases on low-cost polymer or nanoparticle scaffolds, aiming at their potential applications in biomass conversion to fuels. However, some key cellulases carry out the hydrolytic reaction on crystalline cellulose in a directional, processive manner. A large, artificial polycatalytic complex is unlikely to undergo a highly coordinated motion to slide on the cellulose surface as a whole unit. The mechanism underlying the activity enhancements observed in some artificial cellulase complexes and the limit of this approach remain elusive. Herein, we report the synthesis of polycatalytic cellulase complexes bound to colloidal polymer nanoparticles with a magnetic core and describe their unique adsorption, hydrolytic activities, and motions on cellulose. The polycatalytic clusters of cellulases on colloidal polymers show an increased rate of hydrolytic reactions on cellulose, but this was observed mainly at relatively low cellulase-to-cellulose ratios. Enhanced efficiency is mainly attributed to increased local concentrations of cellulases on the scaffolds and their polyvalent interactions with cellulose. However, once bound, the polycatalytic complexes can only carry out reactions locally and are not capable of relocating to new sites rapidly due to their lack of long-range surface mobility and their extremely tight binding. The development of highly optimized polycatalytic complexes may arise by developing novel nanoscaffolds that induce concerted motion of the complex as a whole.
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Affiliation(s)
- Ranjan K Kamat
- Polymer Program, Institute of Material Science, §Department of Chemistry, and ∥Department of Molecular and Cellular Biology, University of Connecticut , Storrs, Connecticut 06269, United States
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Jung J, Sethi A, Gaiotto T, Han JJ, Jeoh T, Gnanakaran S, Goodwin PM. Binding and movement of individual Cel7A cellobiohydrolases on crystalline cellulose surfaces revealed by single-molecule fluorescence imaging. J Biol Chem 2013; 288:24164-72. [PMID: 23818525 DOI: 10.1074/jbc.m113.455758] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The efficient catalytic conversion of biomass to bioenergy would meet a large portion of energy requirements in the near future. A crucial step in this process is the enzyme-catalyzed hydrolysis of cellulose to glucose that is then converted into fuel such as ethanol by fermentation. Here we use single-molecule fluorescence imaging to directly monitor the movement of individual Cel7A cellobiohydrolases from Trichoderma reesei (TrCel7A) on the surface of insoluble cellulose fibrils to elucidate molecular level details of cellulase activity. The motion of multiple, individual TrCel7A cellobiohydrolases was simultaneously recorded with ∼15-nm spatial resolution. Time-resolved localization microscopy provides insights on the activity of TrCel7A on cellulose and informs on nonproductive binding and diffusion. We measured single-molecule residency time distributions of TrCel7A bound to cellulose both in the presence of and absence of cellobiose the major product and a potent inhibitor of Cel7A activity. Combining these results with a kinetic model of TrCel7A binding provides microscopic insight into interactions between TrCel7A and the cellulose substrate.
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Affiliation(s)
- Jaemyeong Jung
- Material Physics and Applications, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
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Jiang F, Kittle JD, Tan X, Esker AR, Roman M. Effects of sulfate groups on the adsorption and activity of cellulases on cellulose substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:3280-91. [PMID: 23452241 DOI: 10.1021/la3040193] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Pretreatment of lignocellulosic biomass with sulfuric acid may leave sulfate groups on its surface that may hinder its biochemical conversion. This study investigates the effects of sulfate groups on cellulase adsorption onto cellulose substrates and the enzymatic hydrolysis of these substrates. Substrates with different sulfate group densities were prepared from H2SO4- and HCl-hydrolyzed and partially and fully desulfated cellulose nanocrystals. Adsorption onto and hydrolysis of the substrates was analyzed by quartz crystal microbalance with dissipation monitoring (QCM-D). The surface roughness of the substrates, measured by atomic force microscopy, increased with decreasing sulfate group density, but their surface accessibilities, measured by QCM-D H2O/D2O exchange experiments, were similar. The adsorption of cellulose binding domains onto sulfated substrates decreased with increasing sulfate group density, but the adsorption of cellulases increased. The rate of hydrolysis of sulfated substrates decreased with increasing sulfate group density. The results indicated an inhibitory effect of sulfate groups on the enzymatic hydrolysis of cellulose, possibly due to nonproductive binding of the cellulases onto the substrates through electrostatic interactions instead of their cellulose binding domains.
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Affiliation(s)
- Feng Jiang
- Macromolecules and Interfaces Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
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