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Long L, Lin Q, Wang J, Ding S. Microbial α-L-arabinofuranosidases: diversity, properties, and biotechnological applications. World J Microbiol Biotechnol 2024; 40:84. [PMID: 38294733 DOI: 10.1007/s11274-023-03882-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Accepted: 12/28/2023] [Indexed: 02/01/2024]
Abstract
Arabinoxylans (AXs) are hemicellulosic polysaccharides consisting of a linear backbone of β-1,4-linked xylose residues branched by high content of α-L-arabinofuranosyl (Araf) residues along with other side-chain substituents, and are abundantly found in various agricultural crops especially cereals. The efficient bioconversion of AXs into monosaccharides, oligosaccharides and/or other chemicals depends on the synergism of main-chain enzymes and de-branching enzymes. Exo-α-L-arabinofuranosidases (ABFs) catalyze the hydrolysis of terminal non-reducing α-1,2-, α-1,3- or α-1,5- linked α-L-Araf residues from arabinose-substituted polysaccharides or oligosaccharides. ABFs are critically de-branching enzymes in bioconversion of agricultural biomass, and have received special attention due to their application potentials in biotechnological industries. In recent years, the researches on microbial ABFs have developed quickly in the aspects of the gene mining, properties of novel members, catalytic mechanisms, methodologies, and application technologies. In this review, we systematically summarize the latest advances in microbial ABFs, and discuss the future perspectives of the enzyme research.
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Affiliation(s)
- Liangkun Long
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.
- Jiangsu Province Key Laboratory of Green Biomass-Based Fuels and Chemicals, Nanjing, 210037, People's Republic of China.
| | - Qunying Lin
- Nanjing Institute for the Comprehensive Utilization of Wild Plants, China CO-OP, Nanjing, 211111, People's Republic of China
| | - Jing Wang
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China
| | - Shaojun Ding
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China
- Jiangsu Province Key Laboratory of Green Biomass-Based Fuels and Chemicals, Nanjing, 210037, People's Republic of China
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Wang R, Zhang Y, Liu L, Yang J, Yuan H. Discovery of a bifunctional xylanolytic enzyme with arabinoxylan arabinofuranohydrolase-d3 and endo-xylanase activities and its application in the hydrolysis of cereal arabinoxylans. Microb Biotechnol 2023. [PMID: 37096984 DOI: 10.1111/1751-7915.14267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 04/11/2023] [Accepted: 04/13/2023] [Indexed: 04/26/2023] Open
Abstract
Xylanolytic enzymes, with both endo-xylanase and arabinoxylan arabinofuranohydrolase (AXH) activities, are attractive for the economically feasible conversion of recalcitrant arabinoxylan. However, their characterization and utilization of these enzymes in biotechnological applications have been limited. Here, we characterize a novel bifunctional enzyme, rAbf43A, cloned from a bacterial consortium that exhibits AXH and endo-xylanase activities. Hydrolytic pattern analyses revealed that the AXH activity belongs to AXHd3 because it attacked only the C(O)-3-linked arabinofuranosyl residues of double-substituted xylopyranosyl units of arabinoxylan and arabinoxylan-derived oligosaccharides, which are usually resistant to hydrolysis. The enzyme rAbf43A also liberated a series of xylo-oligosaccharides (XOSs) from beechwood xylan, xylohexaose and xylopentaose, indicating that rAbf43A exhibited endo-xylanase activity. Homology modelling based on AlphaFold2 and site-directed mutagenesis identified three non-catalytic residues (H161, A270 and L505) located in the substrate-binding pocket essential for its dual-functionality, while the mutation of A117 located in the -1 subsite to the proline residue only affected its endo-xylanase activity. Additionally, rAbf43A showed significant synergistic action with the bifunctional xylanase/feruloyl esterase rXyn10A/Fae1A from the same bacterial consortium on insoluble wheat arabinoxylan and de-starched wheat bran degradation. When rXyn10A/Fae1A was added to the rAbf43A pre-hydrolyzed reactions, the amount of released reducing sugars, xylose and ferulic acid increased by 9.43% and 25.16%, 189.37% and 93.54%, 31.39% and 32.30%, respectively, in comparison with the sum of hydrolysis products released by each enzyme alone. The unique characteristics of rAbf43A position it as a promising candidate not only for designing high-performance enzyme cocktails but also for investigating the structure-function relationship of GH43 multifunctional enzymes.
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Affiliation(s)
- Ruonan Wang
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
- College of Life Science, Luoyang Normal University, Luoyang, China
| | - Yu Zhang
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Liang Liu
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jinshui Yang
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Hongli Yuan
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
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Distinct roles of carbohydrate-binding modules in multidomain β-1,3-1,4-glucanase on polysaccharide degradation. Appl Microbiol Biotechnol 2023; 107:1751-1764. [PMID: 36800030 DOI: 10.1007/s00253-023-12416-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 02/18/2023]
Abstract
Lam16A is a novel GH16 β-1,3-1,4-lichenase isolated from the genus Caldicellulosiruptor which can utilize untreated carbohydrate components of plant cell walls. Its catalytic module has been characterized that the six carbohydrate-binding modules (CBMs) were queued in the C-terminus, but their roles were still unclear. Here, full-length and CBM-truncated mutants of Lam16A were purified and characterized through heterologous expression in Escherichia coli. The profiles of these proteins, including the enzyme activity, degrading efficiency, substrate-binding affinity, and thermostability, were explored. Full-length Lam16A with six CBMs showed excellent thermostability and the highest activity against barley β-glucan and laminarin with optimum pH of 6.5. The CBMs stimulated degrading ability of the catalytic module, especially against β-1,3(4)-glucan-based polysaccharides. The released products from β-1,3-1,4-glucan by Lam16A or its truncated mutants revealed an endo-type glycoside hydrolase. Lam16As exhibited strong binding affinities to the insoluble polysaccharides, especially Lam16A-1CBM. The degradation of yeast cell walls by Lam16A enzyme solution relative to the control reduced the absorbance values at OD800 by ~ 85% ± 1.2, enabling the release of up to ~ 0.057 ± 0.0039 µg/mL of the cytoplasmic protein into the supernatant, lowering the viability of the cells by ~ 70.3% ± 6.9, thus causing significant damage in the cell wall structure. Taken together, CBMs could influence the substrate specificity, thermal stability, and binding affinity of β-1,3-1,4-glucanase. These results demonstrate the great potential of these enzymes to promote the bioavailability of β-1,3-glucan oligosaccharides for health benefits. KEY POINTS: • Carbohydrate-binding modules strongly influenced the enzyme activity and binding affinity, and further impacted glycoside hydrolase activity. • Lam16A enzymes have sufficient ability to hydrolyze β-1,3-1,4-glucan-based polysaccharides. • Lam16As provide a powerful tool to promote the bioavailability of β-1,3-glucan oligosaccharides.
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Crosby JR, Laemthong T, Bing RG, Zhang K, Tanwee TNN, Lipscomb GL, Rodionov DA, Zhang Y, Adams MWW, Kelly RM. Biochemical and Regulatory Analyses of Xylanolytic Regulons in Caldicellulosiruptor bescii Reveal Genus-Wide Features of Hemicellulose Utilization. Appl Environ Microbiol 2022; 88:e0130222. [PMID: 36218355 PMCID: PMC9642015 DOI: 10.1128/aem.01302-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 09/19/2022] [Indexed: 11/20/2022] Open
Abstract
Caldicellulosiruptor species scavenge carbohydrates from runoff containing plant biomass that enters hot springs and from grasses that grow in more moderate parts of thermal features. While only a few Caldicellulosiruptor species can degrade cellulose, all known species are hemicellulolytic. The most well-characterized species, Caldicellulosiruptor bescii, decentralizes its hemicellulase inventory across five different genomic loci and two isolated genes. Transcriptomic analyses, comparative genomics, and enzymatic characterization were utilized to assign functional roles and determine the relative importance of its six putative endoxylanases (five glycoside hydrolase family 10 [GH10] enzymes and one GH11 enzyme) and two putative exoxylanases (one GH39 and one GH3) in C. bescii. Two genus-wide conserved xylanases, C. bescii XynA (GH10) and C. bescii Xyl3A (GH3), had the highest levels of sugar release on oat spelt xylan, were in the top 10% of all genes transcribed by C. bescii, and were highly induced on xylan compared to cellulose. This indicates that a minimal set of enzymes are used to drive xylan degradation in the genus Caldicellulosiruptor, complemented by hemicellulolytic inventories that are tuned to specific forms of hemicellulose in available plant biomasses. To this point, synergism studies revealed that the pairing of specific GH family proteins (GH3, -11, and -39) with C. bescii GH10 proteins released more sugar in vitro than mixtures containing five different GH10 proteins. Overall, this work demonstrates the essential requirements for Caldicellulosiruptor to degrade various forms of xylan and the differences in species genomic inventories that are tuned for survival in unique biotopes with variable lignocellulosic substrates. IMPORTANCE Microbial deconstruction of lignocellulose for the production of biofuels and chemicals requires the hydrolysis of heterogeneous hemicelluloses to access the microcrystalline cellulose portion. This work extends previous in vivo and in vitro efforts to characterize hemicellulose utilization by integrating genomic reconstruction, transcriptomic data, operon structures, and biochemical characteristics of key enzymes to understand the deployment and functionality of hemicellulases by the extreme thermophile Caldicellulosiruptor bescii. Furthermore, comparative genomics of the genus revealed both conserved and divergent mechanisms for hemicellulose utilization across the 15 sequenced species, thereby paving the way to connecting functional enzyme characterization with metabolic engineering efforts to enhance lignocellulose conversion.
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Affiliation(s)
- James R. Crosby
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Tunyaboon Laemthong
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Ryan G. Bing
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Ke Zhang
- Department of Cell and Molecular Biology, College of the Environmental and Life Sciences, University of Rhode Island, Kinston, Rhode Island, USA
| | - Tania N. N. Tanwee
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Gina L. Lipscomb
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Dmitry A. Rodionov
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Ying Zhang
- Department of Cell and Molecular Biology, College of the Environmental and Life Sciences, University of Rhode Island, Kinston, Rhode Island, USA
| | - Michael W. W. Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Robert M. Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
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Geng A, Jin M, Li N, Tu Z, Zhu D, Xie R, Wang Q, Sun J. Arabinan hydrolysis by GH43 enzymes of Hungateiclostridium clariflavum and the potential synergistic mechanisms. Appl Microbiol Biotechnol 2022; 106:7793-7803. [PMID: 36251023 DOI: 10.1007/s00253-022-12238-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 09/30/2022] [Accepted: 10/03/2022] [Indexed: 11/26/2022]
Abstract
Glycoside hydrolase family 43 (GH43) represents a major source of arabinan- and arabinoxylan-active enzymes. Interestingly, some microbes remarkably enriched GH genes of this family, with the reason unknown. Hungateiclostridium clariflavum DSM 19,732 is an efficient lignocellulose degrader, which harbors up to 7 GH43 genes in its genome. We cloned three of the seven GH43 genes, and found that Abn43A is a unique endoarabinanase, which unprecedently showed approximately two times larger activity on sugar beet arabinan (116.8 U/mg) than that on linear arabinan, and it is efficient in arabinooligosaccharide production. Abn43B is an exoarabinanase which directly releases arabinose from linear arabinan. Abn43C is an α-L-arabinofuranosidase which is capable of splitting the arabinose side-chains from arabinooligosaccharides, arabinoxylooligosaccharides, and arabinoxylan. Most importantly, the three GH43 enzymes synergized in hydrolyzing arabinan. Compared to Abn43B alone, a supplement of Abn43A increased the arabinose production from linear arabinan by 150%, reaching 0.44 g/g arabinan. Moreover, an addition of Abn43C to Abn43A and Abn43B boosted the arabinose production from sugar beet arabinan by 15 times, reaching 0.262 g/g arabinan. Our work suggested the intensified functions of multiple GH43 enzymes toward arabinan degradation in H. clariflavum, and a potential synergetic mechanism among the three GH43 enzymes is suggested. KEY POINTS: • Endoarabinanase GH43A prefers branched substrate to linear one • Exoarabinanase GH43B can directly release arabinose from linear arabinan • The three GH43 enzymes synergized in arabinan hydrolysis.
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Affiliation(s)
- Alei Geng
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China.
| | - Meng Jin
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Nana Li
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Zhuowei Tu
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Daochen Zhu
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Rongrong Xie
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Qianqian Wang
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Jianzhong Sun
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China.
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Wu X, Zhang S, Zhao S, Dai L, Huang S, Liu X, Yu J, Wang L. Functional Specificity of Three α-Arabinofuranosidases from Different Glycoside Hydrolase Families in Aspergillus niger An76. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:5039-5048. [PMID: 35420820 DOI: 10.1021/acs.jafc.1c08388] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
α-l-Arabinofuranosidase (Abf), a debranching enzyme that can remove arabinose substituents from arabinoxylan, promotes the hydrolysis of hemicellulose in plant biomass. However, the functional specificity of Abfs from different glycoside hydrolase (GH) families on the digestion of arabinoxylan and their synergistic interaction with xylanase have not been systematically studied. In this work, we characterized three Abfs (AxhA, AbfB, and AbfC) from GH62, GH54, and GH51 families in Aspergillus niger An76. Quantitative transcriptional analysis showed that expression of the axhA gene was upregulated as a result of induction by xylose substrates, whereas expression of the abfB gene was mainly induced by arabinose. Recombinant AxhA, AbfB, and AbfC exhibited different hydrolytic performances. AxhA showed the highest catalytic activity toward wheat arabinoxylan (WAX) and tended to hydrolyze monosubstituted arabinofuranose units, whereas AbfB had higher catalytic activity on AN and debranched arabinan (DAN), having the ability to cope with mono- and disubstituted arabinofuranose units. Furthermore, AbfC had greater arabinofuranosidase activity on p-nitrophenyl-α-l-arabinofuranoside (pNP-AraF) than on other substrates. Moreover, three Abfs displayed obvious synergistic action with GH11 xylanase XynB against WAX and barley husk residues. The elucidation of the degradation mechanisms of Abfs will lay a theoretical foundation for the efficient industrialized transformation of arabinoxylans.
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Affiliation(s)
- Xiuyun Wu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, Shandong, China
- State Key Laboratory of Biological Fermentation Engineering of Beer, Qingdao 266000, Shandong, China
| | - 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
| | - Lin Dai
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, Shandong, China
| | - Shuxia Huang
- State Key Laboratory of Biological Fermentation Engineering of Beer, Qingdao 266000, 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
| | - Junhong Yu
- State Key Laboratory of Biological Fermentation Engineering of Beer, Qingdao 266000, Shandong, China
| | - Lushan Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, Shandong, China
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Saleh MA, Mahmud S, Albogami S, El-Shehawi AM, Paul GK, Islam S, Dutta AK, Uddin MS, Zaman S. Biochemical and Molecular Dynamics Study of a Novel GH 43 α-l-Arabinofuranosidase/β-Xylosidase From Caldicellulosiruptor saccharolyticus DSM8903. Front Bioeng Biotechnol 2022; 10:810542. [PMID: 35223784 PMCID: PMC8881100 DOI: 10.3389/fbioe.2022.810542] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 01/07/2022] [Indexed: 11/13/2022] Open
Abstract
The complete hydrolysis of xylan can be facilitated by the coordinated action of xylanase and other de-branching enzymes. Here, a GH43 α-l-arabinofuranosidase/β-xylosidase (CAX43) from Caldicellulosiruptor saccharolyticus was cloned, sequenced, and biochemically investigated. The interaction of the enzyme with various substrates was also studied. With a half-life of 120 h at 70°C, the produced protein performed maximum activity at pH 6.0 and 70°C. The enzyme demonstrated a higher activity (271.062 ± 4.83 U/mg) against para nitrophenol (pNP) α-L-arabinofuranosides. With xylanase (XynA), the enzyme had a higher degree of synergy (2.30) in a molar ratio of 10:10 (nM). The interaction of the enzyme with three substrates, pNP α-L-arabinofuranosides, pNP β-D-xylopyranosides, and sugar beet arabinan, was investigated using protein modeling, molecular docking, and molecular dynamics (MD) simulation. During the simulation time, the root mean square deviation (RMSD) of the enzyme was below 2.5 Å, demonstrating structural stability. Six, five, and seven binding-interacting residues were confirmed against pNP α-L-arabinofuranosides, pNP β-D-xylopyranosides, and arabinan, respectively, in molecular docking experiments. This biochemical and in silico study gives a new window for understanding the GH43 family’s structural stability and substrate recognition, potentially leading to biological insights and rational enzyme engineering for a new generation of enzymes that perform better and have greater biorefinery utilization.
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Affiliation(s)
- Md. Abu Saleh
- Microbiology Laboratory, Department of Genetic Engineering and Biotechnology, University of Rajshahi, Rajshahi, Bangladesh
- *Correspondence: Md. Abu Saleh,
| | - Shafi Mahmud
- Microbiology Laboratory, Department of Genetic Engineering and Biotechnology, University of Rajshahi, Rajshahi, Bangladesh
| | - Sarah Albogami
- Department of Biotechnology, College of Science, Taif University, Taif, Saudi Arabia
| | - Ahmed M El-Shehawi
- Department of Biotechnology, College of Science, Taif University, Taif, Saudi Arabia
| | - Gobindo Kumar Paul
- Microbiology Laboratory, Department of Genetic Engineering and Biotechnology, University of Rajshahi, Rajshahi, Bangladesh
| | - Shirmin Islam
- Microbiology Laboratory, Department of Genetic Engineering and Biotechnology, University of Rajshahi, Rajshahi, Bangladesh
| | - Amit Kumar Dutta
- Department of Microbiology, University of Rajshahi, Rajshahi, Bangladesh
| | - Md. Salah Uddin
- Microbiology Laboratory, Department of Genetic Engineering and Biotechnology, University of Rajshahi, Rajshahi, Bangladesh
| | - Shahriar Zaman
- Microbiology Laboratory, Department of Genetic Engineering and Biotechnology, University of Rajshahi, Rajshahi, Bangladesh
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Exploration of Two Pectate Lyases from Caldicellulosiruptor bescii Reveals that the CBM66 Module Has a Crucial Role in Pectic Biomass Degradation. Appl Environ Microbiol 2020; 86:AEM.00787-20. [PMID: 32532871 DOI: 10.1128/aem.00787-20] [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: 04/01/2020] [Accepted: 06/07/2020] [Indexed: 02/06/2023] Open
Abstract
Pectin deconstruction is the initial step in breaking the recalcitrance of plant biomass by using selected microorganisms that encode pectinolytic enzymes. Pectate lyases that cleave the α-1,4-galacturonosidic linkage of pectin are widely used in industries such as papermaking and fruit softening. However, there are few reports on pectate lyases with good thermostability. Here, two pectate lyases (CbPL3 and CbPL9) from a hyperthermophilic bacterium, Caldicellulosiruptor bescii, belonging to family 3 and family 9 polysaccharide lyases, respectively, were investigated. The biochemical properties of the two CbPLs were shown to be similar under optimized conditions of 80°C to 85°C and pH 8 to 9. However, the degradation products from pectin and polygalacturonic acids (pGAs) were different. A family 66 carbohydrate-binding module (CbCBM66) located in the N terminus of the two CbPLs shares 100% amino acid identity. A CbCBM66-truncated mutant of CbPL9 showed lower activities than the wild type, whereas CbPL3 with a CbCBM66 knockout portion was reported to have enhanced activities, thereby revealing the different effect of CbCBM66. Prediction by the I-TASSER server revealed that CbCBM66 is structurally close to BsCBM66 from Bacillus subtilis; however, the COFACTOR and COACH programs indicated that the substrate-binding sites between CbCBM66 and BsCBM66 are different. Furthermore, a substrate-binding assay indicated that the catalytic domains in the two CbPLs had strong affinities for pectate-related substrates, but CbCBM66 showed a weak interaction with a number of lignocellulosic carbohydrates. Finally, scanning electron microscopy (SEM) analysis and a total reducing sugar assay showed that the two enzymes could improve the saccharification of switchgrass. The two CbPLs are impressive sources for the degradation of plant biomass.IMPORTANCE Thermophilic proteins could be implemented in diverse industrial applications. We sought to characterize two pectate lyases, CbPL3 and CbPL9, from a thermophilic bacterium, Caldicellulosiruptor bescii The two enzymes share a high optimum temperature, a low optimum pH, and good thermostability at the evaluated temperature. A family 66 carbohydrate-binding module (CbCBM66) was identified in the two CbPLs, sharing 100% amino acid identity. The deletion of CbCBM66 dramatically decreased the activity of CbPL9 but increased the activity and thermostability of CbPL3, suggesting different roles of CbCBM66 in the two enzymes. Moreover, the degradation products of the two CbPLs were different. These results revealed that these enzymes could represent potential pectate lyases for applications in the paper and textile industries.
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9
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Sharma K, Fontes CMGA, Najmudin S, Goyal A. Small angle X-ray scattering based structure, modeling and molecular dynamics analyses of family 43 glycoside hydrolase α-L-arabinofuranosidase from Clostridium thermocellum. J Biomol Struct Dyn 2019; 39:209-218. [PMID: 31856699 DOI: 10.1080/07391102.2019.1707119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Enzymes that participate in the hydrolysis of complex carbohydrates display a modular architecture, although the significance of enzyme modularity to flexibility and catalytic efficacy is not fully understood. α-L-arabinofuranosidase from Clostridium thermocellum (CtAraf43) catalyzes the release of α-1,2-, α-1,3-, or α-1,5- linked L-arabinose from arabinose decorated polysaccharides. CtAraf43 comprises an N-terminal catalytic domain (CtAbf43A) connected with two family 6 carbohydrate-binding modules (CBMs), termed as CtCBM6A and CtCBM6B, through flexible linker peptides. Here, we modeled the structure of CtAraf43 revealing that the module, CtAbf43A displays a 5-fold β-propeller fold and the CBMs the typical jellyroll type β-sandwich folds. Ramachandran plot showed 98.5% residues in the favored region and 1.5% residues in the disallowed region. Molecular dynamics simulation analysis of CtAraf43 revealed significant flexibility that is more expressive in the C-terminal CtCBM6B module in terms of structure and orientation. Small angle X-ray scattering analysis of CtAraf43 revealed its elongated structure. CtAraf43 at 1.2 mg/mL demonstrated the monomeric nature and a multi-modular shaped molecular envelope in solution with a Dmax of 12 nm. However, at 4.7 mg/mL, CtAraf43 displayed a dimeric structure and elongated molecular envelope. Kratky plot analysis revealed the folded state of CtAraf43 with limited flexibility at both concentrations. The data revealed higher flexibility at the C-terminal of CtAraf43 suggesting a coordinated action of the N-terminal catalytic module CtAbf43A and the internal CtCBM6A.AbbreviationCBMsCarbohydrate Binding ModulesCtAraf43α-L-arabinofuranosidaseGHsGlycoside HydrolasesMDMolecular DynamicsRMSDRoot Mean Square DeviationRMSFRoot Mean Square FluctuationSAXSSmall angle X-ray scatteringCommunicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Kedar Sharma
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Carlos M G A Fontes
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portugal
| | - Shabir Najmudin
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portugal
| | - Arun Goyal
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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Tu T, Li X, Meng K, Bai Y, Wang Y, Wang Z, Yao B, Luo H. A GH51 α-L-arabinofuranosidase from Talaromyces leycettanus strain JCM12802 that selectively drives synergistic lignocellulose hydrolysis. Microb Cell Fact 2019; 18:138. [PMID: 31426823 PMCID: PMC6699109 DOI: 10.1186/s12934-019-1192-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 08/10/2019] [Indexed: 12/29/2022] Open
Abstract
Background The development of sustainable technologies for plant cell wall degradation greatly depends on enzymes with hydrolytic activities against carbohydrates. The waste by-products of agricultural cereals are important biomass sources because they contain large amounts of saccharides. Achieving efficient debranching and depolymerization are two important objectives for increasing the utilization of such renewable bioresources. GH51 α-l-arabinofuranosidases are important in biomass pretreatment because they act synergistically with other enzymes during hemicellulose hydrolysis. Results A GH51 α-l-arabinofuranosidase from Talaromyces leycettanus JCM12802 was heterologously expressed in Pichia pastoris GS115 and characterized. The recombinant α-l-arabinofuranosidase, TlAbf51, showed an optimum temperature and pH of 55–60 °C and 3.5–4.0, respectively, and remained stable at 50 °C and pH 3.0–9.0. TlAbf51 showed a higher catalytic efficiency (5712 mM−1 s−1) than most fungal α-l-arabinofuranosidases towards the substrate 4-nitrophenyl-α-l-arabinofuranoside. Moreover, TlAbf51 preferentially removed 1,2- or 1,3-linked arabinofuranose residues from arabinoxylan and acted synergistically with the bifunctional xylanase/cellulase TcXyn10A at an activity ratio of 5:1. The highest yields of arabinose and xylooligosaccharides were obtained when TlAbf51 was added after TcXyn10A or when both enzymes were added simultaneously. High-performance anion-exchange chromatography analyses showed that (i) arabinose and xylooligosaccharides with low degrees of polymerization (DP1–DP5) and (ii) arabinose and xylooligosaccharides (DP1–DP3) were the major hydrolysates obtained during the hydrolysis of sodium hydroxide-pretreated cornstalk and corn bran, respectively. Conclusions In contrast to other fungal GH51 α-l-arabinofuranosidases, recombinant TlAbf51 showed excellent stability over a broad pH range and high catalytic efficiency. Moreover, TlAbf51 acted synergistically with another hemicellulase to digest arabino-polysaccharides. These favorable enzymatic properties make TlAbf51 attractive for biomass pretreatment and biofuel production. Electronic supplementary material The online version of this article (10.1186/s12934-019-1192-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tao Tu
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China.
| | - Xiaoli Li
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China
| | - Kun Meng
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China
| | - Yingguo Bai
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China
| | - Yuan Wang
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China
| | - Zhenxing Wang
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China
| | - Bin Yao
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China
| | - Huiying Luo
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China.
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Lee LL, Crosby JR, Rubinstein GM, Laemthong T, Bing RG, Straub CT, Adams MW, Kelly RM. The biology and biotechnology of the genus Caldicellulosiruptor: recent developments in ‘Caldi World’. Extremophiles 2019; 24:1-15. [DOI: 10.1007/s00792-019-01116-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 07/09/2019] [Indexed: 12/01/2022]
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12
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Pandit RJ, Hinsu AT, Patel SH, Jakhesara SJ, Koringa PG, Bruno F, Psifidi A, Shah SV, Joshi CG. Microbiota composition, gene pool and its expression in Gir cattle (Bos indicus) rumen under different forage diets using metagenomic and metatranscriptomic approaches. Syst Appl Microbiol 2018; 41:374-385. [PMID: 29555111 DOI: 10.1016/j.syapm.2018.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 02/01/2018] [Accepted: 02/01/2018] [Indexed: 01/17/2023]
Abstract
Zebu (Bos indicus) is a domestic cattle species originating from the Indian subcontinent and now widely domesticated on several continents. In this study, we were particularly interested in understanding the functionally active rumen microbiota of an important Zebu breed, the Gir, under different dietary regimes. Metagenomic and metatranscriptomic data were compared at various taxonomic levels to elucidate the differential microbial population and its functional dynamics in Gir cattle rumen under different roughage dietary regimes. Different proportions of roughage rather than the type of roughage (dry or green) modulated microbiome composition and the expression of its gene pool. Fibre degrading bacteria (i.e. Clostridium, Ruminococcus, Eubacterium, Butyrivibrio, Bacillus and Roseburia) were higher in the solid fraction of rumen (P<0.01) compared to the liquid fraction, whereas bacteria considered to be utilizers of the degraded product (i.e. Prevotella, Bacteroides, Parabacteroides, Paludibacter and Victivallis) were dominant in the liquid fraction (P<0.05). Likewise, expression of fibre degrading enzymes and related carbohydrate binding modules (CBMs) occurred in the solid fraction. When metagenomic and metatranscriptomic data were compared, it was found that some genera and species were transcriptionally more active, although they were in low abundance, making an important contribution to fibre degradation and its further metabolism in the rumen. This study also identified some of the transcriptionally active genera, such as Caldicellulosiruptor and Paludibacter, whose potential has been less-explored in rumen. Overall, the comparison of metagenomic shotgun and metatranscriptomic sequencing appeared to be a much richer source of information compared to conventional metagenomic analysis.
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Affiliation(s)
- Ramesh J Pandit
- Department of Animal Biotechnology, College of Veterinary Science and Animal Husbandry, Anand Agricultural University, Anand 388 001, Gujarat, India
| | - Ankit T Hinsu
- Department of Animal Biotechnology, College of Veterinary Science and Animal Husbandry, Anand Agricultural University, Anand 388 001, Gujarat, India
| | - Shriram H Patel
- Department of Animal Biotechnology, College of Veterinary Science and Animal Husbandry, Anand Agricultural University, Anand 388 001, Gujarat, India
| | - Subhash J Jakhesara
- Department of Animal Biotechnology, College of Veterinary Science and Animal Husbandry, Anand Agricultural University, Anand 388 001, Gujarat, India
| | - Prakash G Koringa
- Department of Animal Biotechnology, College of Veterinary Science and Animal Husbandry, Anand Agricultural University, Anand 388 001, Gujarat, India
| | - Fosso Bruno
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council, Via Amendola 165/A, 70126 Bari, Italy
| | - Androniki Psifidi
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, UK; Department of Clinical Science and Services, Royal Veterinary College, North Mymms, Hertfordshire, UK
| | - S V Shah
- Livestock Research Station, College of Veterinary Science & Animal Husbandry, Anand Agricultural University, Anand 388 001, Gujarat, India
| | - Chaitanya G Joshi
- Department of Animal Biotechnology, College of Veterinary Science and Animal Husbandry, Anand Agricultural University, Anand 388 001, Gujarat, India.
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Structural insights into the substrate specificity of a glycoside hydrolase family 5 lichenase from Caldicellulosiruptor sp. F32. Biochem J 2017; 474:3373-3389. [DOI: 10.1042/bcj20170328] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 08/15/2017] [Accepted: 08/23/2017] [Indexed: 01/12/2023]
Abstract
Glycoside hydrolase (GH) family 5 is one of the largest GH families with various GH activities including lichenase, but the structural basis of the GH5 lichenase activity is still unknown. A novel thermostable lichenase F32EG5 belonging to GH5 was identified from an extremely thermophilic bacterium Caldicellulosiruptor sp. F32. F32EG5 is a bi-functional cellulose and a lichenan-degrading enzyme, and exhibited a high activity on β-1,3-1,4-glucan but side activity on cellulose. Thin-layer chromatography and NMR analyses indicated that F32EG5 cleaved the β-1,4 linkage or the β-1,3 linkage while a 4-O-substitued glucose residue linked to a glucose residue through a β-1,3 linkage, which is completely different from extensively studied GH16 lichenase that catalyses strict endo-hydrolysis of the β-1,4-glycosidic linkage adjacent to a 3-O-substitued glucose residue in the mixed-linked β-glucans. The crystal structure of F32EG5 was determined to 2.8 Å resolution, and the crystal structure of the complex of F32EG5 E193Q mutant and cellotetraose was determined to 1.7 Å resolution, which revealed that the exit subsites of substrate-binding sites contribute to both thermostability and substrate specificity of F32EG5. The sugar chain showed a sharp bend in the complex structure, suggesting that a substrate cleft fitting to the bent sugar chains in lichenan is a common feature of GH5 lichenases. The mechanism of thermostability and substrate selectivity of F32EG5 was further demonstrated by molecular dynamics simulation and site-directed mutagenesis. These results provide biochemical and structural insights into thermostability and substrate selectivity of GH5 lichenases, which have potential in industrial processes.
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Enzymatic Mechanism for Arabinan Degradation and Transport in the Thermophilic Bacterium Caldanaerobius polysaccharolyticus. Appl Environ Microbiol 2017; 83:AEM.00794-17. [PMID: 28710263 DOI: 10.1128/aem.00794-17] [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: 04/04/2017] [Accepted: 07/05/2017] [Indexed: 12/21/2022] Open
Abstract
The plant cell wall polysaccharide arabinan provides an important supply of arabinose, and unraveling arabinan-degrading strategies by microbes is important for understanding its use as a source of energy. Here, we explored the arabinan-degrading enzymes in the thermophilic bacterium Caldanaerobius polysaccharolyticus and identified a gene cluster encoding two glycoside hydrolase (GH) family 51 α-l-arabinofuranosidases (CpAbf51A, CpAbf51B), a GH43 endoarabinanase (CpAbn43A), a GH27 β-l-arabinopyranosidase (CpAbp27A), and two GH127 β-l-arabinofuranosidases (CpAbf127A, CpAbf127B). The genes were expressed as recombinant proteins, and the functions of the purified proteins were determined with para-nitrophenyl (pNP)-linked sugars and naturally occurring pectin structural elements as the substrates. The results demonstrated that CpAbn43A is an endoarabinanase while CpAbf51A and CpAbf51B are α-l-arabinofuranosidases that exhibit diverse substrate specificities, cleaving α-1,2, α-1,3, and α-1,5 linkages of purified arabinan-oligosaccharides. Furthermore, both CpAbf127A and CpAbf127B cleaved β-arabinofuranose residues in complex arabinan side chains, thus providing evidence of the function of this family of enzymes on such polysaccharides. The optimal temperatures of the enzymes ranged between 60°C and 75°C, and CpAbf43A and CpAbf51A worked synergistically to release arabinose from branched and debranched arabinan. Furthermore, the hydrolytic activity on branched arabinan oligosaccharides and degradation of pectic substrates by the endoarabinanase and l-arabinofuranosidases suggested a microbe equipped with diverse activities to degrade complex arabinan in the environment. Based on our functional analyses of the genes in the arabinan degradation cluster and the substrate-binding studies on a component of the cognate transporter system, we propose a model for arabinan degradation and transport by C. polysaccharolyticusIMPORTANCE Genomic DNA sequencing and bioinformatic analysis allowed the identification of a gene cluster encoding several proteins predicted to function in arabinan degradation and transport in C. polysaccharolyticus The analysis of the recombinant proteins yielded detailed insights into the putative arabinan metabolism of this thermophilic bacterium. The use of various branched arabinan oligosaccharides provided a detailed understanding of the substrate specificities of the enzymes and allowed assignment of two new GH127 polypeptides as β-l-arabinofuranosidases able to degrade pectic substrates, thus expanding our knowledge of this rare group of glycoside hydrolases. In addition, the enzymes showed synergistic effects for the degradation of arabinans at elevated temperatures. The enzymes characterized from the gene cluster are, therefore, of utility for arabinose production in both the biofuel and food industries.
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