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Wu X, Zhao S, Tian Z, Han C, Jiang X, Wang L. Dynamics of loops surrounding the active site architecture in GH5_2 subfamily TfCel5A for cellulose degradation. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:154. [PMID: 37853500 PMCID: PMC10583438 DOI: 10.1186/s13068-023-02411-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/12/2023] [Indexed: 10/20/2023]
Abstract
BACKGROUND Lignocellulose is the most abundant natural biomass resource for the production of biofuels and other chemicals. The efficient degradation of cellulose by cellulases is a critical step for the lignocellulose bioconversion. Understanding the structure-catalysis relationship is vital for rational design of more stable and highly active enzymes. Glycoside hydrolase (GH) family 5 is the largest and most functionally diverse group of cellulases, with a conserved TIM barrel structure. The important roles of the various loop regions of GH5 enzymes in catalysis, however, remain poorly understood. RESULTS In the present study, we investigated the relationship between the loops surrounding active site architecture and its catalytic efficiency, taking TfCel5A, an enzyme from GH5_2 subfamily of Thermobifida fusca, as an example. Large-scale computational simulations and site-directed mutagenesis experiments revealed that three loops (loop 8, 3, and 7) around active cleft played diverse roles in substrate binding, intermediate formation, and product release, respectively. The highly flexible and charged residue triad of loop 8 was responsible for capturing the ligand into the active cleft. Severe fluctuation of loop 3 led to the distortion of sugar conformation at the - 1 subsite. The wobble of loop 7 might facilitate product release, and the enzyme activity of the mutant Y361W in loop 7 was increased by approximately 40%. CONCLUSION This study unraveled the vital roles of loops in active site architecture and provided new insights into the catalytic mechanism of the GH5_2 cellulases.
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Affiliation(s)
- Xiuyun Wu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Sha Zhao
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Zhennan Tian
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Chao Han
- Shandong Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018, China
| | - Xukai Jiang
- National Glycoengineering Research Center, Shandong University, Qingdao, 266237, China
| | - Lushan Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237, China.
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Wang Z, Fan C, Zheng X, Jin Z, Bei K, Zhao M, Kong H. Roles of Surfactants in Oriented Immobilization of Cellulase on Nanocarriers and Multiphase Hydrolysis System. Front Chem 2022; 10:884398. [PMID: 35402378 PMCID: PMC8983819 DOI: 10.3389/fchem.2022.884398] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 03/09/2022] [Indexed: 11/16/2022] Open
Abstract
Surfactants, especially non-ionic surfactants, play an important role in the preparation of nanocarriers and can also promote the enzymatic hydrolysis of lignocellulose. A broad overview of the current status of surfactants on the immobilization of cellulase is provided in this review. In addition, the restricting factors in cellulase immobilization in the complex multiphase hydrolysis system are discussed, including the carrier structure characteristics, solid-solid contact obstacles, external diffusion resistance, limited recycling frequency, and nonproductive combination of enzyme active centers. Furthermore, promising prospects of cellulase-oriented immobilization are proposed, including the hydrophilic-hydrophobic interaction of surfactants and cellulase in the oil-water reaction system, the reversed micelle system of surfactants, and the possible oriented immobilization mechanism.
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Affiliation(s)
- Zhiquan Wang
- School of Life and Environmental Science, Wenzhou University, Wenzhou, China
- State and Local Joint Engineering Research Center for Ecological Treatment Technology of Urban Water Pollution, Wenzhou, China
- Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Wenzhou, China
| | - Chunzhen Fan
- School of Life and Environmental Science, Wenzhou University, Wenzhou, China
- State and Local Joint Engineering Research Center for Ecological Treatment Technology of Urban Water Pollution, Wenzhou, China
- Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Wenzhou, China
| | - Xiangyong Zheng
- School of Life and Environmental Science, Wenzhou University, Wenzhou, China
- State and Local Joint Engineering Research Center for Ecological Treatment Technology of Urban Water Pollution, Wenzhou, China
- Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Wenzhou, China
| | - Zhan Jin
- School of Life and Environmental Science, Wenzhou University, Wenzhou, China
- State and Local Joint Engineering Research Center for Ecological Treatment Technology of Urban Water Pollution, Wenzhou, China
- Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Wenzhou, China
| | - Ke Bei
- School of Life and Environmental Science, Wenzhou University, Wenzhou, China
- State and Local Joint Engineering Research Center for Ecological Treatment Technology of Urban Water Pollution, Wenzhou, China
- Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Wenzhou, China
| | - Min Zhao
- School of Life and Environmental Science, Wenzhou University, Wenzhou, China
- State and Local Joint Engineering Research Center for Ecological Treatment Technology of Urban Water Pollution, Wenzhou, China
- Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Wenzhou, China
| | - Hainan Kong
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
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Systematic Functional and Computational Analysis of Glucose-Binding Residues in Glycoside Hydrolase Family GH116. Catalysts 2022. [DOI: 10.3390/catal12030343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022] Open
Abstract
Glycoside hydrolases (GH) bind tightly to the sugar moiety at the glycosidic bond being hydrolyzed to stabilize its transition state conformation. We endeavored to assess the importance of glucose-binding residues in GH family 116 (GH116) β-glucosidases, which include human β-glucosylceramidase 2 (GBA2), by mutagenesis followed by kinetic characterization, X-ray crystallography, and ONIOM calculations on Thermoanaerobacterium xylanolyticum TxGH116, the structural model for GH116 enzymes. Mutations of residues that bind at the glucose C3OH and C4OH caused 27–196-fold increases in KM for p-nitrophenyl-β-D-glucoside, and significant decreases in the kcat, up to 5000-fold. At the C6OH binding residues, mutations of E777 decreased the kcat/KM by over 60,000-fold, while R786 mutants increased both the KM (40-fold) and kcat (2–4-fold). The crystal structures of R786A and R786K suggested a larger entrance to the active site could facilitate their faster rates. ONIOM binding energy calculations identified D452, H507, E777, and R786, along with the catalytic residues E441 and D593, as strong electrostatic contributors to glucose binding with predicted interaction energies > 15 kcal mol−1, consistent with the effects of the D452, H507, E777 and R786 mutations on enzyme kinetics. The relative importance of GH116 active site residues in substrate binding and catalysis identified in this work improves the prospects for the design of inhibitors for GBA2 and the engineering of GH116 enzymes for hydrolytic and synthetic applications.
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Zhang S, Zhao S, Shang W, Yan Z, Wu X, Li Y, Chen G, Liu X, Wang L. Synergistic mechanism of GH11 xylanases with different action modes from Aspergillus niger An76. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:118. [PMID: 33971954 PMCID: PMC8112042 DOI: 10.1186/s13068-021-01967-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 05/03/2021] [Indexed: 05/28/2023]
Abstract
BACKGROUND Xylan is the most abundant hemicellulose polysaccharide in nature, which can be converted into high value-added products. However, its recalcitrance to breakdown requires the synergistic action of multiple enzymes. Aspergillus niger, possessing numerous xylan degrading isozyme-encoding genes, are highly effective xylan degraders in xylan-rich habitats. Therefore, it is necessary to explore gene transcription, the mode of action and cooperation mechanism of different xylanase isozymes to further understand the efficient xylan-degradation by A. niger. RESULTS Aspergillus niger An76 encoded a comprehensive set of xylan-degrading enzymes, including five endo-xylanases (one GH10 and four GH11). Quantitative transcriptional analysis showed that three xylanase genes (xynA, xynB and xynC) were up-regulated by xylan substrates, and the order and amount of enzyme secretion differed. Specifically, GH11 xylanases XynA and XynB were initially secreted successively, followed by GH10 xylanase XynC. Biochemical analyses displayed that three GH11 xylanases (XynA, XynB and XynD) showed differences in catalytic performance and product profiles, possibly because of intricate hydrogen bonding between substrates and functional residues in the active site architectures impacted their binding capacity. Among these, XynB had the best performance in the degradation of xylan and XynE had no catalytic activity. Furthermore, XynA and XynB showed synergistic effects during xylan degradation. CONCLUSIONS The sequential secretion and different action modes of GH11 xylanases were essential for the efficient xylan degradation by A. niger An76. The elucidation of the degradation mechanisms of these xylanase isozymes further improved our understanding of GH-encoding genes amplification in filamentous fungi and may guide the design of the optimal enzyme cocktails in industrial applications.
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Affiliation(s)
- Shu Zhang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237 Shandong China
| | - Sha Zhao
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237 Shandong China
- School of Life Sciences, Shandong University, Qingdao, 266237 Shandong China
| | - Weihao Shang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237 Shandong China
| | - Zijuan Yan
- School of Life Sciences, Shandong University, Qingdao, 266237 Shandong China
| | - Xiuyun Wu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237 Shandong China
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan, 250353 Shandong China
| | - Yingjie Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237 Shandong China
| | - Guanjun Chen
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237 Shandong China
| | - Xinli Liu
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan, 250353 Shandong China
| | - Lushan Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, 266237 Shandong China
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Yu Y, Ding X, Ding Z, Wang Y, Song Y. Fluorescence spectroscopy and molecular docking analysis of the binding of Lactobacillus acidophilus GIM1.208 β-glucosidase with quercetin glycosides. Enzyme Microb Technol 2021; 146:109761. [PMID: 33812560 DOI: 10.1016/j.enzmictec.2021.109761] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 02/02/2021] [Accepted: 02/02/2021] [Indexed: 10/22/2022]
Abstract
Lactobacillus acidophilus is an important probiotic. The β-glucosidase produced by L. acidophilus GIM1.208 can transform quercetin glycosides of Rosa roxburghii Tratt to release quercetin and improve the functional activity of raw materials. Understanding the interaction and the characteristics of the two will lay a theoretical foundation for the site-directed transformation and functional application of the catalytic active site of enzymes. In our study, using the heterologously expressed and highly stable, purified L. acidophilus GIM1.208 BGL as the strain, the representative quercetin in β-glucosidase and Rosa roxburghii Tratt was preliminarily predicted and explored using ultraviolet-visible absorption spectroscopy. Fluorescence spectroscopy combined with molecular docking was used to determine the interaction characteristics of the glycoside substrates, rutin (Rut) and isoquercitrin (Iso). Results from molecular docking showed that Asp159, Arg56, Iso294, Phe292, and Gly25 were the main residues of β-glucosidase and Rut. Arg56 was found to be the most crucial residue of β-glucosidase and isoquercitrin; the interaction between Rut and Iso and β-glucosidase was mainly driven by hydrogen bonding. The combined free energy of β-glucosidase and Iso was found to be -182.10 kcal/mol, while that of β-glucosidase and Rut was -32.37 kcal/mol. The results of fluorescence spectroscopy showed that the fluorescence intensity of β-glucosidase decreased with an increase in Rut and Iso concentrations. This interaction made β-glucosidase quench endogenous fluorescence, which was static quenching. The binding constants of Rut and Iso with β-glucosidase were determined to be 0.50×107 and 0.31×107 L/mol, respectively, indicating that rutin had a stronger affinity when interacting with β-glucosidase. These findings were consistent with our prediction results determined using molecular docking studies.
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Affiliation(s)
- Yihong Yu
- School of Liquor & Food Engineering, Guizhou University, National Forestry and Grassland Bureau Prickly Pear Engineering Technology Research Center, Key Laboratory of Agricultural and Animal Products Store and Processing of Guizhou Province, Guiyang, 550025, China
| | - Xiaojuan Ding
- School of Liquor & Food Engineering, Guizhou University, National Forestry and Grassland Bureau Prickly Pear Engineering Technology Research Center, Key Laboratory of Agricultural and Animal Products Store and Processing of Guizhou Province, Guiyang, 550025, China
| | - Zhuhong Ding
- School of Liquor & Food Engineering, Guizhou University, National Forestry and Grassland Bureau Prickly Pear Engineering Technology Research Center, Key Laboratory of Agricultural and Animal Products Store and Processing of Guizhou Province, Guiyang, 550025, China.
| | - Yi Wang
- School of Liquor & Food Engineering, Guizhou University, National Forestry and Grassland Bureau Prickly Pear Engineering Technology Research Center, Key Laboratory of Agricultural and Animal Products Store and Processing of Guizhou Province, Guiyang, 550025, China
| | - Yuting Song
- School of Liquor & Food Engineering, Guizhou University, National Forestry and Grassland Bureau Prickly Pear Engineering Technology Research Center, Key Laboratory of Agricultural and Animal Products Store and Processing of Guizhou Province, Guiyang, 550025, China
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Revisiting the Phenomenon of Cellulase Action: Not All Endo- and Exo-Cellulase Interactions Are Synergistic. Catalysts 2021. [DOI: 10.3390/catal11020170] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The conventional endo–exo synergism model has extensively been supported in literature, which is based on the perception that endoglucanases (EGs) expose or create accessible sites on the cellulose chain to facilitate the action of processive cellobiohydrolases (CBHs). However, there is a lack of information on why some bacterial and fungal CBHs and EGs do not exhibit synergism. Therefore, the present study evaluated and compared the synergistic relationships between cellulases from different microbial sources and provided insights into how different GH families govern synergism. The results showed that CmixA2 (a mixture of TlCel7A and CtCel5A) displayed the highest effect with BaCel5A (degree of synergy for reducing sugars and glucose of 1.47 and 1.41, respectively) in a protein mass ratio of 75–25%. No synergism was detected between CmixB1/B2 (as well as CmixC1/C2) and any of the EGs, and the combinations did not improve the overall cellulose hydrolysis. These findings further support the hypothesis that “not all endo-to exo-cellulase interactions are synergistic”, and that the extent of synergism is dependent on the composition of cellulase systems from various sources and their compatibility in the cellulase cocktail. This method of screening for maximal compatibility between exo- and endo-cellulases constitutes a critical step towards the design of improved synergistic cellulose-degrading cocktails for industrial-scale biomass degradation.
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The contribution of specific subsites to catalytic activities in active site architecture of a GH11 xylanase. Appl Microbiol Biotechnol 2020; 104:8735-8745. [DOI: 10.1007/s00253-020-10865-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/11/2020] [Accepted: 08/26/2020] [Indexed: 12/14/2022]
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Malik A, Kim YR, Jang IH, Hwang S, Oh DC, Kim SB. Genome-based analysis for the bioactive potential of Streptomyces yeochonensis CN732, an acidophilic filamentous soil actinobacterium. BMC Genomics 2020; 21:118. [PMID: 32013859 PMCID: PMC6998099 DOI: 10.1186/s12864-020-6468-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 01/08/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Acidophilic members of the genus Streptomyces can be a good source for novel secondary metabolites and degradative enzymes of biopolymers. In this study, a genome-based approach on Streptomyces yeochonensis CN732, a representative neutrotolerant acidophilic streptomycete, was employed to examine the biosynthetic as well as enzymatic potential, and also presence of any genetic tools for adaptation in acidic environment. RESULTS A high quality draft genome (7.8 Mb) of S. yeochonensis CN732 was obtained with a G + C content of 73.53% and 6549 protein coding genes. The in silico analysis predicted presence of multiple biosynthetic gene clusters (BGCs), which showed similarity with those for antimicrobial, anticancer or antiparasitic compounds. However, the low levels of similarity with known BGCs for most cases suggested novelty of the metabolites from those predicted gene clusters. The production of various novel metabolites was also confirmed from the combined high performance liquid chromatography-mass spectrometry analysis. Through comparative genome analysis with related Streptomyces species, genes specific to strain CN732 and also those specific to neutrotolerant acidophilic species could be identified, which showed that genes for metabolism in diverse environment were enriched among acidophilic species. In addition, the presence of strain specific genes for carbohydrate active enzymes (CAZyme) along with many other singletons indicated uniqueness of the genetic makeup of strain CN732. The presence of cysteine transpeptidases (sortases) among the BGCs was also observed from this study, which implies their putative roles in the biosynthesis of secondary metabolites. CONCLUSIONS This study highlights the bioactive potential of strain CN732, an acidophilic streptomycete with regard to secondary metabolite production and biodegradation potential using genomics based approach. The comparative genome analysis revealed genes specific to CN732 and also those among acidophilic species, which could give some insights into the adaptation of microbial life in acidic environment.
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Affiliation(s)
- Adeel Malik
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Yu Ri Kim
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - In Hee Jang
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Sunghoon Hwang
- Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Dong-Chan Oh
- Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Seung Bum Kim
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, 34134, Republic of Korea.
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Sarkar I, Tisa LS, Gtari M, Sen A. Biosynthetic energy cost of potentially highly expressed proteins vary with niche in selected actinobacteria. J Basic Microbiol 2017; 58:154-161. [PMID: 29144540 DOI: 10.1002/jobm.201700350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 10/27/2017] [Accepted: 11/05/2017] [Indexed: 11/08/2022]
Abstract
Amino acid and protein biosynthesis requires a number of high energy phosphate bonds and includes a dual energy cost for the synthesis of chemical intermediates during the fueling reactions and the conversion of precursor molecules to final products. One popular hypothesis is that the proteins encoded by putative highly expressed genes (hence called PHXPs) generally utilize low energy consuming amino acids to reduce the biosynthetic cost of the essential proteins. In our study, we found that this idea was not supported in the case of actinobacteria. With the actinobacteria, the energy costs of PHXPs varied in relation to their niche. Free-living, including aquatic, soil and extremophilic, and plant-associated actinobacteria were found to use energetically expensive amino acids in their PHXPs. An exception occurred with some animal-host-associated actinobacteria that used energy efficient amino acids. One explanation for these results may be due to the diverse metabolic patterns exhibited by actinobacteria under varied niches influenced by nutritional availability and physical environment.
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Affiliation(s)
- Indrani Sarkar
- NBU Bioinformatics Facility, Department of Botany, University of North Bengal, Siliguri, India
| | - Louis S Tisa
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire
| | - Maher Gtari
- Laboratoire Microorganismes et Biomolécules Actives, Université de Tunis Elmanar (FST), Université de Carthage (INSAT), Tunis, Tunisia
| | - Arnab Sen
- NBU Bioinformatics Facility, Department of Botany, University of North Bengal, Siliguri, India
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Carbohydrate active enzyme domains from extreme thermophiles: components of a modular toolbox for lignocellulose degradation. Extremophiles 2017; 22:1-12. [PMID: 29110088 DOI: 10.1007/s00792-017-0974-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/24/2017] [Indexed: 02/06/2023]
Abstract
Lignocellulosic biomass is a promising feedstock for the manufacture of biodegradable and renewable bioproducts. However, the complex lignocellulosic polymeric structure of woody tissue is difficult to access without extensive industrial pre-treatment. Enzyme processing of partly depolymerised biomass is an established technology, and there is evidence that high temperature (extremely thermophilic) lignocellulose degrading enzymes [carbohydrate active enzymes (CAZymes)] may enhance processing efficiency. However, wild-type thermophilic CAZymes will not necessarily be functionally optimal under industrial pre-treatment conditions. With recent advances in synthetic biology, it is now potentially possible to build CAZyme constructs from individual protein domains, tailored to the conditions of specific industrial processes. In this review, we identify a 'toolbox' of thermostable CAZyme domains from extremely thermophilic organisms and highlight recent advances in CAZyme engineering which will allow for the rational design of CAZymes tailored to specific aspects of lignocellulose digestion.
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Wu X, Tian Z, Jiang X, Zhang Q, Wang L. Enhancement in catalytic activity of Aspergillus niger XynB by selective site-directed mutagenesis of active site amino acids. Appl Microbiol Biotechnol 2017; 102:249-260. [DOI: 10.1007/s00253-017-8607-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 10/10/2017] [Accepted: 10/12/2017] [Indexed: 01/25/2023]
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Loop 3 of Fungal Endoglucanases of Glycoside Hydrolase Family 12 Modulates Catalytic Efficiency. Appl Environ Microbiol 2017; 83:AEM.03123-16. [PMID: 28039140 DOI: 10.1128/aem.03123-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 12/28/2016] [Indexed: 01/25/2023] Open
Abstract
Glycoside hydrolase (GH) family 12 comprises enzymes with a wide range of activities critical for the degradation of lignocellulose. However, the important roles of the loop regions of GH12 enzymes in substrate specificity and catalytic efficiency remain poorly understood. This study examined how the loop 3 region affects the enzymatic properties of GH12 glucanases using NfEG12A from Neosartorya fischeri P1 and EG (PDB 1KS4) from Aspergillus niger Acidophilic and thermophilic NfEG12A had the highest catalytic efficiency (kcat/Km , 3,001 and 263 ml/mg/s toward lichenin and carboxymethyl cellulose sodium [CMC-Na], respectively) known so far. Based on the multiple-sequence alignment and homology modeling, two specific sequences (FN and STTQA) were identified in the loop 3 region of GH12 endoglucanases from fungi. To determine their functions, these sequences were introduced into NfEG12A, or the counterpart sequence STTQA was removed from EG. These modifications had no effects on the optimal pH and temperature or substrate specificity but changed the catalytic efficiency (kcat/Km ) of these enzymes (in descending order, NfEG12A [100%], NfEG12A-FN [140%], and NfEG12A-STTQA [190%]; EG [100%] and EGΔSTTQA [41%]). Molecular docking and dynamic simulation analyses revealed that the longer loop 3 in GH12 may strengthen the hydrogen-bond interactions between the substrate and protein, thereby increasing the turnover rate (kcat). This study provides a new insight to understand the vital roles of loop 3 for GH12 endoglucanases in catalysis.IMPORTANCE Loop structures play critical roles in the substrate specificity and catalytic hydrolysis of GH12 enzymes. Three typical loops exist in these enzymes. Loops 1 and 2 are recognized as the catalytic loops and are closely related to the substrate specificity and catalytic efficiency. Loop 3 locates in the -1 or +1 subsite and varies a lot in amino acid composition, which may play a role in catalysis. In this study, two GH12 glucanases, NfEG12A and EG, which were mutated by introducing or deleting partial loop 3 sequences FN and/or STTQA, were selected to identify the function of loop 3. It revealed that the longer loop 3 of GH12 glucanases may strengthen the hydrogen network interactions between the substrate and protein, consequently increasing the turnover rate (kcat). This study proposes a strategy to increase the catalytic efficiency of GH12 glucanases by improving the hydrogen network between substrates and catalytic loops.
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Jiang X, Li W, Chen G, Wang L. Dynamic Perturbation of the Active Site Determines Reversible Thermal Inactivation in Glycoside Hydrolase Family 12. J Chem Inf Model 2017; 57:288-297. [DOI: 10.1021/acs.jcim.6b00692] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xukai Jiang
- State Key Laboratory
of Microbial
Technology, Shandong University, Jinan 250100, China
| | - Wen Li
- State Key Laboratory
of Microbial
Technology, Shandong University, Jinan 250100, China
| | - Guanjun Chen
- State Key Laboratory
of Microbial
Technology, Shandong University, Jinan 250100, China
| | - Lushan Wang
- State Key Laboratory
of Microbial
Technology, Shandong University, Jinan 250100, China
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Garg R, Srivastava R, Brahma V, Verma L, Karthikeyan S, Sahni G. Biochemical and structural characterization of a novel halotolerant cellulase from soil metagenome. Sci Rep 2016; 6:39634. [PMID: 28008971 PMCID: PMC5180356 DOI: 10.1038/srep39634] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 11/25/2016] [Indexed: 12/20/2022] Open
Abstract
Cellulase catalyzes the hydrolysis of β-1,4-linkages of cellulose to produce industrially relevant monomeric subunits. Cellulases find their applications in pulp and paper, laundry, food and feed, textile, brewing industry and in biofuel production. These industries always have great demand for cellulases that can work efficiently even in harsh conditions such as high salt, heat, and acidic environments. While, cellulases with high thermal and acidic stability are already in use, existence of a high halotolerant cellulase is still elusive. Here, we report a novel cellulase Cel5R, obtained from soil metagenome that shows high halotolerance and thermal stability. The biochemical and functional characterization of Cel5R revealed its endoglucanase activity and high halostability. In addition, the crystal structure of Cel5R determined at 2.2 Å resolution reveals a large number of acidic residues on the surface of the protein that contribute to the halophilic nature of this enzyme. Moreover, we demonstrate that the four free and non-conserved cysteine residues (C65, C90, C231 and C273) contributes to the thermal stability of Cel5R by alanine scanning experiments. Thus, the newly identified endoglucanase Cel5R is a promising candidate for various industrial applications.
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Affiliation(s)
- Roma Garg
- CSIR-Institute Of Microbial Technology, Council Of Scientific and Industrial Research (CSIR), Sector 39 A, Chandigarh 160036, India
| | - Ritika Srivastava
- CSIR-Institute Of Microbial Technology, Council Of Scientific and Industrial Research (CSIR), Sector 39 A, Chandigarh 160036, India
| | - Vijaya Brahma
- CSIR-Institute Of Microbial Technology, Council Of Scientific and Industrial Research (CSIR), Sector 39 A, Chandigarh 160036, India
| | - Lata Verma
- CSIR-Institute Of Microbial Technology, Council Of Scientific and Industrial Research (CSIR), Sector 39 A, Chandigarh 160036, India
| | - Subramanian Karthikeyan
- CSIR-Institute Of Microbial Technology, Council Of Scientific and Industrial Research (CSIR), Sector 39 A, Chandigarh 160036, India
| | - Girish Sahni
- CSIR-Institute Of Microbial Technology, Council Of Scientific and Industrial Research (CSIR), Sector 39 A, Chandigarh 160036, India
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15
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Gong W, Zhang H, Tian L, Liu S, Wu X, Li F, Wang L. Determination of the modes of action and synergies of xylanases by analysis of xylooligosaccharide profiles over time using fluorescence-assisted carbohydrate electrophoresis. Electrophoresis 2016; 37:1640-50. [PMID: 27060349 DOI: 10.1002/elps.201600041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/21/2016] [Accepted: 03/23/2016] [Indexed: 01/06/2023]
Abstract
The structure of xylan, which has a 1,4-linked β-xylose backbone with various substituents, is much more heterogeneous and complex than that of cellulose. Because of this, complete degradation of xylan needs a large number of enzymes that includes GH10, GH11, and GH3 family xylanases together with auxiliary enzymes. Fluorescence-assisted carbohydrate electrophoresis (FACE) is able to accurately differentiate unsubstituted and substituted xylooligosaccharides (XOS) in the heterogeneous products generated by different xylanases and allows changes in concentrations of specific XOS to be analyzed quantitatively. Based on a quantitative analysis of XOS profiles over time using FACE, we have demonstrated that GH10 and GH11 family xylanases immediately degrade xylan into sizeable XOS, which are converted into smaller XOS in a much lower speed. The shortest substituted XOS produced by hydrolysis of the substituted xylan backbone by GH10 and GH11 family xylanases were MeGlcA(2) Xyl3 and MeGlcA(2) Xyl4 , respectively. The unsubstituted xylan backbone was degraded into xylose, xylobiose, and xylotriose by both GH10 and GH11 family xylanases; the product profiles are not family-specific but, instead, depend on different subsite binding affinities in the active sites of individual enzymes. Synergystic action between xylanases and β-xylosidase degraded MeGlcA(2) Xyl4 into xylose and MeGlcA(2) Xyl3 but further degradation of MeGlcA(2) Xyl3 required additional enzymes. Synergy between xylanases and β-xylosidase was also found to significantly accelerate the conversion of XOS into xylose.
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Affiliation(s)
- Weili Gong
- The State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong, P. R. China
| | - Huaiqiang Zhang
- The State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong, P. R. China
| | - Li Tian
- The State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong, P. R. China
| | - Shijia Liu
- Taishan College, Shandong University, Jinan, Shandong, P. R. China
| | - Xiuyun Wu
- The State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong, P. R. China
| | - Fuli Li
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, P. R. China
| | - Lushan Wang
- The State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong, P. R. China
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16
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Ligand-binding specificity and promiscuity of the main lignocellulolytic enzyme families as revealed by active-site architecture analysis. Sci Rep 2016; 6:23605. [PMID: 27009476 PMCID: PMC4806347 DOI: 10.1038/srep23605] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 03/09/2016] [Indexed: 02/02/2023] Open
Abstract
Biomass can be converted into sugars by a series of lignocellulolytic enzymes, which belong to the glycoside hydrolase (GH) families summarized in CAZy databases. Here, using a structural bioinformatics method, we analyzed the active site architecture of the main lignocellulolytic enzyme families. The aromatic amino acids Trp/Tyr and polar amino acids Glu/Asp/Asn/Gln/Arg occurred at higher frequencies in the active site architecture than in the whole enzyme structure. And the number of potential subsites was significantly different among different families. In the cellulase and xylanase families, the conserved amino acids in the active site architecture were mostly found at the −2 to +1 subsites, while in β-glucosidase they were mainly concentrated at the −1 subsite. Families with more conserved binding amino acid residues displayed strong selectivity for their ligands, while those with fewer conserved binding amino acid residues often exhibited promiscuity when recognizing ligands. Enzymes with different activities also tended to bind different hydroxyl oxygen atoms on the ligand. These results may help us to better understand the common and unique structural bases of enzyme-ligand recognition from different families and provide a theoretical basis for the functional evolution and rational design of major lignocellulolytic enzymes.
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17
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Jiang X, Chen G, Wang L. Structural and dynamic evolution of the amphipathic N-terminus diversifies enzyme thermostability in the glycoside hydrolase family 12. Phys Chem Chem Phys 2016; 18:21340-50. [DOI: 10.1039/c6cp02998a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The N-terminus diversifies enzyme thermostability in the GH12 family, which was investigated by MD simulations, and provides potential applications in protein engineering.
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Affiliation(s)
- Xukai Jiang
- State Key Laboratory of Microbial Technology
- Shandong University
- Jinan 250100
- China
| | - Guanjun Chen
- State Key Laboratory of Microbial Technology
- Shandong University
- Jinan 250100
- China
| | - Lushan Wang
- State Key Laboratory of Microbial Technology
- Shandong University
- Jinan 250100
- China
- State Key Laboratory of Biochemical Engineering
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