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Capetti CCDM, Ontañon O, Navas LE, Campos E, Simister R, Dowle A, Liberato MV, Pellegrini VDOA, Gómez LD, Polikarpov I. Sugarcane bagasse derived xylooligosaccharides produced by an arabinofuranosidase/xylobiohydrolase from Bifidobacterium longum in synergism with xylanases. Carbohydr Polym 2024; 339:122248. [PMID: 38823916 DOI: 10.1016/j.carbpol.2024.122248] [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: 12/26/2023] [Revised: 05/03/2024] [Accepted: 05/07/2024] [Indexed: 06/03/2024]
Abstract
Arabinoxylan is a major hemicellulose in the sugarcane plant cell wall with arabinose decorations that impose steric restrictions on the activity of xylanases against this substrate. Enzymatic removal of the decorations by arabinofuranosidases can allow a more efficient arabinoxylan degradation by xylanases. Here we produced and characterized a recombinant Bifidobacterium longum arabinofuranosidase from glycoside hydrolase family 43 (BlAbf43) and applied it, together with GH10 and GH11 xylanases, to produce xylooligosaccharides (XOS) from wheat arabinoxylan and alkali pretreated sugarcane bagasse. The enzyme synergistically enhanced XOS production by GH10 and GH11 xylanases, being particularly efficient in combination with the latter family of enzymes, with a degree of synergism of 1.7. We also demonstrated that the enzyme is capable of not only removing arabinose decorations from the arabinoxylan and from the non-reducing end of the oligomeric substrates, but also hydrolyzing the xylan backbone yielding mostly xylobiose and xylose in particular cases. Structural studies of BlAbf43 shed light on the molecular basis of the substrate recognition and allowed hypothesizing on the structural reasons of its multifunctionality.
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Affiliation(s)
- Caio Cesar de Mello Capetti
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | - Ornella Ontañon
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), CICVyA, Instituto Nacional de Tecnología Agropecuaria (INTA), Los Reseros y N. Repetto, Hurlingham B1686, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Laura E Navas
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), CICVyA, Instituto Nacional de Tecnología Agropecuaria (INTA), Los Reseros y N. Repetto, Hurlingham B1686, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Eleonora Campos
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), CICVyA, Instituto Nacional de Tecnología Agropecuaria (INTA), Los Reseros y N. Repetto, Hurlingham B1686, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Rachael Simister
- Centre for Novel Agricultural Products, Department of Biology, CNAP, University of York, York YO10 5DD, United Kingdom
| | - Adam Dowle
- Technology Facility, Proteomics Laboratory, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Marcelo Vizoná Liberato
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | | | - Leonardo D Gómez
- Centre for Novel Agricultural Products, Department of Biology, CNAP, University of York, York YO10 5DD, United Kingdom.
| | - Igor Polikarpov
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil.
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Topalian J, Navas L, Ontañon O, Valacco MP, Noseda DG, Blasco M, Peña MJ, Urbanowicz BR, Campos E. Production of a bacterial secretome highly efficient for the deconstruction of xylans. World J Microbiol Biotechnol 2024; 40:266. [PMID: 38997527 DOI: 10.1007/s11274-024-04075-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Accepted: 07/06/2024] [Indexed: 07/14/2024]
Abstract
Bacteria within the Paenibacillus genus are known to secrete a diverse array of enzymes capable of breaking down plant cell wall polysaccharides. We studied the extracellular xylanolytic activity of Paenibacillus xylanivorans and examined the complete range of secreted proteins when grown on carbohydrate-based carbon sources of increasing complexity, including wheat bran, sugar cane straw, beechwood xylan and sucrose, as control. Our data showed that the relative abundances of secreted proteins varied depending on the carbon source used. Extracellular enzymatic extracts from wheat bran (WB) or sugar cane straw (SCR) cultures had the highest xylanolytic activity, coincidently with the largest representation of carbohydrate active enzymes (CAZymes). Scaling-up to a benchtop bioreactor using WB resulted in a significant enhancement in productivity and in the overall volumetric extracellular xylanase activity, that was further concentrated by freeze-drying. The enzymatic extract was efficient in the deconstruction of xylans from different sources as well as sugar cane straw pretreated by alkali extrusion (SCRe), resulting in xylobiose and xylose, as primary products. The overall yield of xylose released from SCRe was improved by supplementing the enzymatic extract with a recombinant GH43 β-xylosidase (EcXyl43) and a GH62 α-L-arabinofuranosidase (CsAbf62A), two activities that were under-represented. Overall, we showed that the extracellular enzymatic extract from P. xylanivorans, supplemented with specific enzymatic activities, is an effective approach for targeting xylan within lignocellulosic biomass.
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Affiliation(s)
- Juliana Topalian
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), De los Reseros y N. Repetto s/n, Hurlingham, Buenos Aires, B1686IGC, Argentina
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Laura Navas
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), De los Reseros y N. Repetto s/n, Hurlingham, Buenos Aires, B1686IGC, Argentina
| | - Ornella Ontañon
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), De los Reseros y N. Repetto s/n, Hurlingham, Buenos Aires, B1686IGC, Argentina
| | - Maria Pia Valacco
- Centro de Estudios Químicos y Biológicos por Espectrometría de Masa (CEQUIBIEM-FCEN), Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires (UBA-IQUIBICEN), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Diego Gabriel Noseda
- Instituto de Investigaciones Biotecnológicas (IIBio), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de San Martín, San Martín, Buenos Aires, Argentina
| | - Martín Blasco
- Departamento de Bioprocesos, Instituto Nacional de Tecnología Industrial (INTI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Maria Jesus Peña
- Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, 315 Riverbend Road, Athens, GA, USA
| | - Breeanna R Urbanowicz
- Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, 315 Riverbend Road, Athens, GA, USA
| | - Eleonora Campos
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), De los Reseros y N. Repetto s/n, Hurlingham, Buenos Aires, B1686IGC, Argentina.
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Rodríguez-Sanz A, Fuciños C, Soares C, Torrado AM, Lima N, Rúa ML. A comprehensive method for the sequential separation of extracellular xylanases and β-xylosidases/arabinofuranosidases from a new Fusarium species. Int J Biol Macromol 2024; 272:132722. [PMID: 38821304 DOI: 10.1016/j.ijbiomac.2024.132722] [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: 12/22/2023] [Revised: 05/23/2024] [Accepted: 05/27/2024] [Indexed: 06/02/2024]
Abstract
Several fungal species produce diverse carbohydrate-active enzymes useful for the xylooligosaccharide biorefinery. These enzymes can be isolated by different purification methods, but fungi usually produce other several compounds which interfere in the purification process. So, the present work has three interconnected aims: (i) compare β-xylosidase production by Fusarium pernambucanum MUM 18.62 with other crop pathogens; (ii) optimise F. pernambucanum xylanolytic enzymes expression focusing on the pre-inoculum media composition; and (iii) design a downstream strategy to eliminate interfering substances and sequentially isolate β-xylosidases, arabinofuranosidases and endo-xylanases from the extracellular media. F. pernambucanum showed the highest β-xylosidase activity among all the evaluated species. It also produced endo-xylanase and arabinofuranosidase. The growth and β-xylosidase expression were not influenced by the pre-inoculum source, contrary to endo-xylanase activity, which was higher with xylan-enriched agar. Using a sequential strategy involving ammonium sulfate precipitation of the extracellular interferences, and several chromatographic steps of the supernatant (hydrophobic chromatography, size exclusion chromatography, and anion exchange chromatography), we were able to isolate different enzyme pools: four partially purified β-xylosidase/arabinofuranoside; FpXylEAB trifunctional GH10 endo-xylanase/β-xylosidase/arabinofuranoside enzyme (39.8 kDa) and FpXynE GH11 endo-xylanase with molecular mass (18.0 kDa). FpXylEAB and FpXynE enzymes were highly active at pH 5-6 and 60-50 °C.
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Affiliation(s)
- Andrea Rodríguez-Sanz
- Biochemistry Laboratory, Department of Analytical and Food Chemistry, University of Vigo, Ourense, Spain
| | - Clara Fuciños
- Biochemistry Laboratory, Department of Analytical and Food Chemistry, University of Vigo, Ourense, Spain
| | - Célia Soares
- CEB-Biological Engineering Centre, University of Minho, Campus de Gualtar, Braga, Portugal; LABBELS-Associate Laboratory, Braga, Guimarães, Portugal
| | - Ana M Torrado
- Biochemistry Laboratory, Department of Analytical and Food Chemistry, University of Vigo, Ourense, Spain
| | - Nelson Lima
- CEB-Biological Engineering Centre, University of Minho, Campus de Gualtar, Braga, Portugal; LABBELS-Associate Laboratory, Braga, Guimarães, Portugal
| | - María L Rúa
- Biochemistry Laboratory, Department of Analytical and Food Chemistry, University of Vigo, Ourense, Spain.
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Li N, Zhang R, Zhou J, Huang Z. Structures, Biochemical Characteristics, and Functions of β-Xylosidases. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:7961-7976. [PMID: 37192316 DOI: 10.1021/acs.jafc.3c01425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The complete degradation of abundant xylan derived from plants requires the participation of β-xylosidases to produce the xylose which can be converted to xylitol, ethanol, and other valuable chemicals. Some phytochemicals can also be hydrolyzed by β-xylosidases into bioactive substances, such as ginsenosides, 10-deacetyltaxol, cycloastragenol, and anthocyanidins. On the contrary, some hydroxyl-containing substances such as alcohols, sugars, and phenols can be xylosylated by β-xylosidases into new chemicals such as alkyl xylosides, oligosaccharides, and xylosylated phenols. Thus, β-xylosidases shows great application prospects in food, brewing, and pharmaceutical industries. This review focuses on the molecular structures, biochemical properties, and bioactive substance transformation function of β-xylosidases derived from bacteria, fungi, actinomycetes, and metagenomes. The molecular mechanisms of β-xylosidases related to the properties and functions are also discussed. This review will serve as a reference for the engineering and application of β-xylosidases in food, brewing, and pharmaceutical industries.
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Affiliation(s)
- Na Li
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming 650500, People's Republic of China
- College of Life Sciences, Yunnan Normal University, Kunming 650500, People's Republic of China
- Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Kunming 650500, People's Republic of China
- Key Laboratory of Yunnan Provincial Education Department for Plateau Characteristic Food Enzymes, Kunming 650500, People's Republic of China
| | - Rui Zhang
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming 650500, People's Republic of China
- College of Life Sciences, Yunnan Normal University, Kunming 650500, People's Republic of China
- Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Kunming 650500, People's Republic of China
- Key Laboratory of Yunnan Provincial Education Department for Plateau Characteristic Food Enzymes, Kunming 650500, People's Republic of China
| | - Junpei Zhou
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming 650500, People's Republic of China
- College of Life Sciences, Yunnan Normal University, Kunming 650500, People's Republic of China
- Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Kunming 650500, People's Republic of China
- Key Laboratory of Yunnan Provincial Education Department for Plateau Characteristic Food Enzymes, Kunming 650500, People's Republic of China
| | - Zunxi Huang
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming 650500, People's Republic of China
- College of Life Sciences, Yunnan Normal University, Kunming 650500, People's Republic of China
- Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment, Kunming 650500, People's Republic of China
- Key Laboratory of Yunnan Provincial Education Department for Plateau Characteristic Food Enzymes, Kunming 650500, People's Republic of China
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Madubuike H, Ferry N. Characterisation of a Novel Acetyl Xylan Esterase (BaAXE) Screened from the Gut Microbiota of the Common Black Slug ( Arion ater). Molecules 2022; 27:2999. [PMID: 35566348 PMCID: PMC9104356 DOI: 10.3390/molecules27092999] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 05/03/2022] [Indexed: 11/24/2022] Open
Abstract
Acetyl xylan esterases (AXEs) are enzymes capable of hydrolysing the acetyl bonds in acetylated xylan, allowing for enhanced activity of backbone-depolymerizing enzymes. Bioprospecting novel AXE is essential in designing enzyme cocktails with desired characteristics targeting the complete breakdown of lignocellulose. In this article, we report the characterisation of a novel AXE identified as Gene_id_40363 in the metagenomic library analysed from the gut microbiota of the common black slug. The conserved domain description was identified with an NCBI BLASTp search using the translated nucleotide sequence as a query. The activity of the recombinant enzyme was tested on various synthetic substrates and acetylated substrates. The protein sequence matched the conserved domain described as putative hydrolase and aligned closely to an uncharacterized esterase from Buttiauxella agrestis, hence the designation as BaAXE. BaAXE showed low sequence similarity among characterized CE family proteins with an available 3D structure. BaAXE was active on 4-nitrophenyl acetate, reporting a specific activity of 78.12 U/mg and a Km value of 0.43 mM. The enzyme showed optimal activity at 40 °C and pH 8 and showed high thermal stability, retaining over 40% activity after 2 h of incubation from 40 °C to 100 °C. BaAXE hydrolysed acetyl bonds, releasing acetic acid from acetylated xylan and β-D-glucose pentaacetate. BaAXE has great potential for biotechnological applications harnessing its unique characteristics. In addition, this proves the possibility of bioprospecting novel enzymes from understudied environments.
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Affiliation(s)
- Henry Madubuike
- School of Science, Engineering and Environment, University of Salford, Manchester M5 4WT, UK
| | - Natalie Ferry
- School of Science, Engineering and Environment, University of Salford, Manchester M5 4WT, UK
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Optimisation of xylanases production by two Cellulomonas strains and their use for biomass deconstruction. Appl Microbiol Biotechnol 2021; 105:4577-4588. [PMID: 34019113 PMCID: PMC8195749 DOI: 10.1007/s00253-021-11305-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 03/19/2021] [Accepted: 04/18/2021] [Indexed: 11/12/2022]
Abstract
Abstract One of the main distinguishing features of bacteria belonging to the Cellulomonas genus is their ability to secrete multiple polysaccharide degrading enzymes. However, their application in biomass deconstruction still constitutes a challenge. We addressed the optimisation of the xylanolytic activities in extracellular enzymatic extracts of Cellulomonas sp. B6 and Cellulomonas fimi B-402 for their subsequent application in lignocellulosic biomass hydrolysis by culture in several substrates. As demonstrated by secretomic profiling, wheat bran and waste paper resulted to be suitable inducers for the secretion of xylanases of Cellulomonas sp. B6 and C. fimi B-402, respectively. Both strains showed high xylanolytic activity in culture supernatant although Cellulomonas sp. B6 was the most efficient xylanolytic strain. Upscaling from flasks to fermentation in a bench scale bioreactor resulted in equivalent production of extracellular xylanolytic enzymatic extracts and freeze drying was a successful method for concentration and conservation of the extracellular enzymes, retaining 80% activity. Moreover, enzymatic cocktails composed of combined extra and intracellular extracts effectively hydrolysed the hemicellulose fraction of extruded barley straw into xylose and xylooligosaccharides. Key points • Secreted xylanase activity of Cellulomonas sp. B6 and C. fimi was maximised. • Biomass-induced extracellular enzymes were identified by proteomic profiling. • Combinations of extra and intracellular extracts were used for barley straw hydrolysis. Supplementary Information The online version contains supplementary material available at 10.1007/s00253-021-11305-y.
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Briganti L, Capetti C, Pellegrini VO, Ghio S, Campos E, Nascimento AS, Polikarpov I. Structural and molecular dynamics investigations of ligand stabilization via secondary binding site interactions in Paenibacillus xylanivorans GH11 xylanase. Comput Struct Biotechnol J 2021; 19:1557-1566. [PMID: 33815691 PMCID: PMC7994722 DOI: 10.1016/j.csbj.2021.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 02/27/2021] [Accepted: 03/01/2021] [Indexed: 12/25/2022] Open
Abstract
Glycoside hydrolases (GHs) are essential for plant biomass deconstruction. GH11 family consist of endo-β-1,4-xylanases which hydrolyze xylan, the second most abundant cell wall biopolymer after cellulose, into small bioavailable oligomers. Structural requirements for enzymatic mechanism of xylan hydrolysis is well described for GH11 members. However, over the last years, it has been discovered that some enzymes from GH11 family have a secondary binding sites (SBS), which modulate the enzymes activities, but mechanistic details of the molecular communication between the active site and SBS of the enzymes remain a conundrum. In the present work we structurally characterized GH11 xylanase from Paenibacillus xylanivorans A57 (PxXyn11B), a microorganism of agricultural importance, using protein crystallography and molecular dynamics simulations. The PxXyn11B structure was solved to 2.5 Å resolution and different substrates (xylo-oligosaccharides from X3 to X6), were modelled in its active and SBS sites. Molecular Dynamics (MD) simulations revealed an important role of SBS in the activity and conformational mobility of PxXyn11B, demonstrating that binding of the reaction products to the SBS of the enzyme stabilizes the N-terminal region and, consequently, the active site. Furthermore, MD simulations showed that the longer the ligand, the better is the stabilization within active site, and the positive subsites contribute less to the stabilization of the substrates than the negative ones. These findings provide rationale for the observed enzyme kinetics, shedding light on the conformational modulation of the GH11 enzymes via their SBS mediated by the positive molecular feedback loop which involve the products of the enzymatic reaction.
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Affiliation(s)
- Lorenzo Briganti
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | - Caio Capetti
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | - Vanessa O.A. Pellegrini
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | - Silvina Ghio
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), CONICET-INTA, Los Reseros y Nicolas Repetto (s/n), Hurlingham (1686), Prov. Buenos Aires, Argentina
| | - Eleonora Campos
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), CONICET-INTA, Los Reseros y Nicolas Repetto (s/n), Hurlingham (1686), Prov. Buenos Aires, Argentina
| | - Alessandro S. Nascimento
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | - Igor Polikarpov
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
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β-Xylosidases: Structural Diversity, Catalytic Mechanism, and Inhibition by Monosaccharides. Int J Mol Sci 2019; 20:ijms20225524. [PMID: 31698702 PMCID: PMC6887791 DOI: 10.3390/ijms20225524] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/02/2019] [Accepted: 11/04/2019] [Indexed: 12/20/2022] Open
Abstract
Xylan, a prominent component of cellulosic biomass, has a high potential for degradation into reducing sugars, and subsequent conversion into bioethanol. This process requires a range of xylanolytic enzymes. Among them, β-xylosidases are crucial, because they hydrolyze more glycosidic bonds than any of the other xylanolytic enzymes. They also enhance the efficiency of the process by degrading xylooligosaccharides, which are potent inhibitors of other hemicellulose-/xylan-converting enzymes. On the other hand, the β-xylosidase itself is also inhibited by monosaccharides that may be generated in high concentrations during the saccharification process. Structurally, β-xylosidases are diverse enzymes with different substrate specificities and enzyme mechanisms. Here, we review the structural diversity and catalytic mechanisms of β-xylosidases, and discuss their inhibition by monosaccharides.
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