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Abstract
Many enzymes that show a large specificity in binding the enzymatic transition state with a higher affinity than the substrate utilize substrate binding energy to drive protein conformational changes to form caged substrate complexes. These protein cages provide strong stabilization of enzymatic transition states. Using part of the substrate binding energy to drive the protein conformational change avoids a similar strong stabilization of the Michaelis complex and irreversible ligand binding. A seminal step in the development of modern enzyme catalysts was the evolution of enzymes that couple substrate binding to a conformational change. These include enzymes that function in glycolysis (triosephosphate isomerase), the biosynthesis of lipids (glycerol phosphate dehydrogenase), the hexose monophosphate shunt (6-phosphogluconate dehydrogenase), and the mevalonate pathway (isopentenyl diphosphate isomerase), catalyze the final step in the biosynthesis of pyrimidine nucleotides (orotidine monophosphate decarboxylase), and regulate the cellular levels of adenine nucleotides (adenylate kinase). The evolution of enzymes that undergo ligand-driven conformational changes to form active protein-substrate cages is proposed to proceed by selection of variants, in which the selected side chain substitutions destabilize a second protein conformer that shows compensating enhanced binding interactions with the substrate. The advantages inherent to enzymes that incorporate a conformational change into the catalytic cycle provide a strong driving force for the evolution of flexible protein folds such as the TIM barrel. The appearance of these folds represented a watershed event in enzyme evolution that enabled the rapid propagation of enzyme activities within enzyme superfamilies.
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Affiliation(s)
- John P Richard
- Department of Chemistry, University at Buffalo, the State University of New York, Buffalo, New York 14260-3000, United States
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2
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Su WB, Li FL, Li XY, Fan XM, Liu RJ, Zhang YW. Using galactitol dehydrogenase coupled with water-forming NADH oxidase for efficient enzymatic synthesis of L-tagatose. N Biotechnol 2021; 62:18-25. [PMID: 33460816 DOI: 10.1016/j.nbt.2021.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 01/05/2021] [Accepted: 01/11/2021] [Indexed: 10/22/2022]
Abstract
L-Tagatose, a promising building block in the production of many value-added chemicals, is generally produced by chemical routes with a low yield, which may not meet the increasing demands. Synthesis of l-tagatose by enzymatic oxidation of d-galactitol has not been applied on an industrial scale because of the high cofactor costs and the lack of efficient cofactor regeneration methods. In this work, an efficient and environmentally friendly enzymatic method containing a galactitol dehydrogenase for d-galactitol oxidation and a water-forming NADH oxidase for regeneration of NAD+ was first designed and used for l-tagatose production. Supplied with only 3 mM NAD+, subsequent reaction optimization facilitated the efficient transformation of 100 mM of d-galactitol into l-tagatose with a yield of 90.2 % after 12 h (obtained productivity: 7.61 mM.h-1). Compared with the current chemical and biocatalytic methods, the strategy developed avoids by-product formation and achieves the highest yield of l-tagatose with low costs. It is expected to become a cleaner and more promising route for industrial biosynthesis of l-tagatose.
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Affiliation(s)
- Wen-Bin Su
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Fei-Long Li
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Xue-Yong Li
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Xiao-Man Fan
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Rui-Jiang Liu
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Ye-Wang Zhang
- School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China; College of Petroleum and Chemical Engineering, Beibu Gulf University, Qinzhou, 535011, People's Republic of China.
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3
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Tang R, Ye P, Alper HS, Liu Z, Zhao X, Bai F. Identification and characterization of novel xylose isomerases from a Bos taurus fecal metagenome. Appl Microbiol Biotechnol 2019; 103:9465-9477. [PMID: 31701197 DOI: 10.1007/s00253-019-10161-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/08/2019] [Accepted: 09/28/2019] [Indexed: 12/31/2022]
Abstract
Discovering sugar metabolism genes is of great interest for lignocellulosic biorefinery. Xylose isomerases (XIs) were commonly screened from metagenomes derived from bovine rumen, soil, and other sources. However, so far, XIs and other sugar-utilizing enzymes have not been discovered from fecal metagenomes. In this study, environmental DNA from the fecal samples collected from yellow cattle (Bos taurus) was sequenced and analyzed. In the whole 14.26 Gbp clean data, 92 putative XIs were annotated. After sequence analysis, seven putative XIs were heterologously expressed in Escherichia coli and characterized in vitro. The XIs 58444 and 58960 purified from E. coli exhibited 22% higher enzyme activity when compared with that of the native E. coli XI. The XI 58444, similar to the XI from Lachnospira multipara, exhibited a relatively stable activity profile across different pH conditions. Four XIs were further investigated in budding yeast Saccharomyces cerevisiae after codon optimization. Overexpression of the codon-optimized 58444 enabled S. cerevisiae to utilize 6.4 g/L xylose after 96 h without any other genetic manipulations, which is 56% higher than the control yeast strain overexpressing an optimized XI gene xylA*3 selected by three rounds of mutation. Our results provide evidence that a bovine fecal metagenome is a novel and valuable source of XIs and other industrial enzymes for biotechnology applications.
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Affiliation(s)
- Ruiqi Tang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Peiliang Ye
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Hal S Alper
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Zhanying Liu
- School of Chemical Engineering, Inner Mongolia University of Technology, Hohhot, 010051, China.,Center for Conservation and Emission Reductioin in Fermentation Industry, Inner Mongolia, Hohhot, 010051, China
| | - Xinqing Zhao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Fengwu Bai
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
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4
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Understanding xylose isomerase from Burkholderia cenocepacia: insights into structure and functionality for ethanol production. AMB Express 2019; 9:73. [PMID: 31127459 PMCID: PMC6534634 DOI: 10.1186/s13568-019-0795-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 05/13/2019] [Indexed: 12/21/2022] Open
Abstract
The inability of the yeast Saccharomyces cerevisiae to produce ethanol from xylose has hampered the biofuel production from lignocellulosic biomass. However, prior studies reveal that functional expression of xylose isomerase (XI) from Burkholderia cenocepacia (XylABc) in S. cerevisiae has remarkably improved xylose consumption and ethanol productivity. Yet, little is known about kinetic and structural properties of this enzyme. Hereby, a purified recombinant XylA was assayed in vitro, showing optimal enzyme activity at 37 °C and pH 7.2. The Km of XylA for d-xylose was at least threefold lower than the Km results for any XI published to date (e.g. XylA from Piromyces sp.). In addition, oligomerization behavior as a tetramer was observed for XylA in solution. Functional and structural comparative analyses amongst three microbial XIs were further performed as theoretical models, showing that xylose orientation at the active site was highly conserved among the XIs. Mg2+ ions anchor the sugar and guide its pyranoside oxygen towards a histidine residue present at the active site, allowing an acid–base reaction, linearizing xylose. Electrostatic surface analyses showed that small variations in the net charge distribution and dipole moment could directly affect the way the substrate interacts with the protein, thus altering its kinetic properties. Accordingly, in silico modeling suggested the tetramer may be the major functional form. These analyses and the resulting model promote a better understanding of this protein family and pave the way to further protein engineering and application of XylA in the ethanol industry.
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Recombinant Diploid Saccharomyces cerevisiae Strain Development for Rapid Glucose and Xylose Co-Fermentation. FERMENTATION-BASEL 2018. [DOI: 10.3390/fermentation4030059] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cost-effective production of cellulosic ethanol requires robust microorganisms for rapid co-fermentation of glucose and xylose. This study aims to develop a recombinant diploid xylose-fermenting Saccharomyces cerevisiae strain for efficient conversion of lignocellulosic biomass sugars to ethanol. Episomal plasmids harboring codon-optimized Piromyces sp. E2 xylose isomerase (PirXylA) and Orpinomyces sp. ukk1 xylose (OrpXylA) genes were constructed and transformed into S. cerevisiae. The strain harboring plasmids with tandem PirXylA was favorable for xylose utilization when xylose was used as the sole carbon source, while the strain harboring plasmids with tandem OrpXylA was beneficial for glucose and xylose cofermentation. PirXylA and OrpXylA genes were also individually integrated into the genome of yeast strains in multiple copies. Such integration was beneficial for xylose alcoholic fermentation. The respiration-deficient strain carrying episomal or integrated OrpXylA genes exhibited the best performance for glucose and xylose co-fermentation. This was partly attributed to the high expression levels and activities of xylose isomerase. Mating a respiration-efficient strain carrying the integrated PirXylA gene with a respiration-deficient strain harboring integrated OrpXylA generated a diploid recombinant xylose-fermenting yeast strain STXQ with enhanced cell growth and xylose fermentation. Co-fermentation of 162 g L−1 glucose and 95 g L−1 xylose generated 120.6 g L−1 ethanol in 23 h, with sugar conversion higher than 99%, ethanol yield of 0.47 g g−1, and ethanol productivity of 5.26 g L−1·h−1.
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xylA and xylB overexpression as a successful strategy for improving xylose utilization and poly-3-hydroxybutyrate production in Burkholderia sacchari. ACTA ACUST UNITED AC 2018; 45:165-173. [DOI: 10.1007/s10295-018-2007-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/08/2018] [Indexed: 12/31/2022]
Abstract
Abstract
Despite the versatility and many advantages of polyhydroxyalkanoates as petroleum-based plastic substitutes, their higher production cost compared to petroleum-based polymers has historically limited their large-scale production. One appealing approach to reducing production costs is to employ less expensive, renewable feedstocks. Xylose, for example is an abundant and inexpensive carbon source derived from hemicellulosic residues abundant in agro-industrial waste (sugarcane bagasse hemicellulosic hydrolysates). In this work, the production of poly-3-hydroxybutyrate P(3HB) from xylose was studied to develop technologies for conversion of agro-industrial waste into high-value chemicals and biopolymers. Specifically, this work elucidates the organization of the xylose assimilation operon of Burkholderia sacchari, a non-model bacterium with high capacity for P(3HB) accumulation. Overexpression of endogenous xylose isomerase and xylulokinase genes was successfully assessed, improving both specific growth rate and P(3HB) production. Compared to control strain (harboring pBBR1MCS-2), xylose utilization in the engineered strain was substantially improved with 25% increase in specific growth rate, 34% increase in P(3HB) production, and the highest P(3HB) yield from xylose reported to date for B. sacchari (Y P3HB/Xil = 0.35 g/g). This study highlights that xylA and xylB overexpression is an effective strategy to improve xylose utilization and P(3HB) production in B. sacchari.
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Verhoeven MD, Lee M, Kamoen L, van den Broek M, Janssen DB, Daran JMG, van Maris AJA, Pronk JT. Mutations in PMR1 stimulate xylose isomerase activity and anaerobic growth on xylose of engineered Saccharomyces cerevisiae by influencing manganese homeostasis. Sci Rep 2017; 7:46155. [PMID: 28401919 PMCID: PMC5388867 DOI: 10.1038/srep46155] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 03/09/2017] [Indexed: 01/04/2023] Open
Abstract
Combined overexpression of xylulokinase, pentose-phosphate-pathway enzymes and a heterologous xylose isomerase (XI) is required but insufficient for anaerobic growth of Saccharomyces cerevisiae on d-xylose. Single-step Cas9-assisted implementation of these modifications yielded a yeast strain expressing Piromyces XI that showed fast aerobic growth on d-xylose. However, anaerobic growth required a 12-day adaptation period. Xylose-adapted cultures carried mutations in PMR1, encoding a Golgi Ca2+/Mn2+ ATPase. Deleting PMR1 in the parental XI-expressing strain enabled instantaneous anaerobic growth on d-xylose. In pmr1 strains, intracellular Mn2+ concentrations were much higher than in the parental strain. XI activity assays in cell extracts and reconstitution experiments with purified XI apoenzyme showed superior enzyme kinetics with Mn2+ relative to other divalent metal ions. This study indicates engineering of metal homeostasis as a relevant approach for optimization of metabolic pathways involving metal-dependent enzymes. Specifically, it identifies metal interactions of heterologous XIs as an underexplored aspect of engineering xylose metabolism in yeast.
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Affiliation(s)
- Maarten D Verhoeven
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Misun Lee
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Lycka Kamoen
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Marcel van den Broek
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Dick B Janssen
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Jean-Marc G Daran
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Antonius J A van Maris
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Jack T Pronk
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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Ko JK, Um Y, Lee SM. Effect of manganese ions on ethanol fermentation by xylose isomerase expressing Saccharomyces cerevisiae under acetic acid stress. BIORESOURCE TECHNOLOGY 2016; 222:422-430. [PMID: 27744166 DOI: 10.1016/j.biortech.2016.09.130] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 09/29/2016] [Accepted: 09/30/2016] [Indexed: 06/06/2023]
Abstract
The efficient fermentation of lignocellulosic hydrolysates in the presence of inhibitors is highly desirable for bioethanol production. Among the inhibitors, acetic acid released during the pretreatment of lignocellulose negatively affects the fermentation performance of biofuel producing organisms. In this study, we evaluated the inhibitory effects of acetic acid on glucose and xylose fermentation by a high performance engineered strain of xylose utilizing Saccharomyces cerevisiae, SXA-R2P-E, harboring a xylose isomerase based pathway. The presence of acetic acid severely decreased the xylose fermentation performance of this strain. However, the acetic acid stress was alleviated by metal ion supplementation resulting in a 52% increased ethanol production rate under 2g/L of acetic acid stress. This study shows the inhibitory effect of acetic acid on an engineered isomerase-based xylose utilizing strain and suggests a simple but effective method to improve the co-fermentation performance under acetic acid stress for efficient bioethanol production.
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Affiliation(s)
- Ja Kyong Ko
- Clean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Youngsoon Um
- Clean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea; Clean Energy and Chemical Engineering, Korea University of Science and Technology, Daejeon 34113, Republic of Korea
| | - Sun-Mi Lee
- Clean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea; Clean Energy and Chemical Engineering, Korea University of Science and Technology, Daejeon 34113, Republic of Korea.
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9
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Crook N, Abatemarco J, Sun J, Wagner JM, Schmitz A, Alper HS. In vivo continuous evolution of genes and pathways in yeast. Nat Commun 2016; 7:13051. [PMID: 27748457 PMCID: PMC5071640 DOI: 10.1038/ncomms13051] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 08/30/2016] [Indexed: 11/17/2022] Open
Abstract
Directed evolution remains a powerful, highly generalizable approach for improving the performance of biological systems. However, implementations in eukaryotes rely either on in vitro diversity generation or limited mutational capacities. Here we synthetically optimize the retrotransposon Ty1 to enable in vivo generation of mutant libraries up to 1.6 × 107 l−1 per round, which is the highest of any in vivo mutational generation approach in yeast. We demonstrate this approach by using in vivo-generated libraries to evolve single enzymes, global transcriptional regulators and multi-gene pathways. When coupled to growth selection, this approach enables in vivo continuous evolution (ICE) of genes and pathways. Through a head-to-head comparison, we find that ICE libraries yield higher-performing variants faster than error-prone PCR-derived libraries. Finally, we demonstrate transferability of ICE to divergent yeasts, including Kluyveromyces lactis and alternative S. cerevisiae strains. Collectively, this work establishes a generic platform for rapid eukaryotic-directed evolution across an array of target cargo. Directed evolution is a powerful technique for generating improved biological systems through repeated rounds of mutagenesis and selection. Here the authors engineer the yeast retrotransposon Ty1 to enable the creation of large mutant libraries in vivo and use this system to generate improved variants of single enzymes and multigene pathways.
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Affiliation(s)
- Nathan Crook
- Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Stop C0400, Austin, Texas 78712, USA
| | - Joseph Abatemarco
- Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Stop C0400, Austin, Texas 78712, USA
| | - Jie Sun
- Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Stop C0400, Austin, Texas 78712, USA
| | - James M Wagner
- Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Stop C0400, Austin, Texas 78712, USA
| | - Alexander Schmitz
- Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Stop C0400, Austin, Texas 78712, USA
| | - Hal S Alper
- Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Stop C0400, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, 2500 Speedway Avenue, Austin, Texas 78712, USA
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10
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Lajoie CA, Kitner JB, Potochnik SJ, Townsend JM, Beatty CC, Kelly CJ. Cloning, expression and characterization of xylose isomerase from the marine bacteriumFulvimarina pelagiinEscherichia coli. Biotechnol Prog 2016; 32:1230-1237. [DOI: 10.1002/btpr.2309] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/27/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Curtis A. Lajoie
- School of Chemical, Biological, and Environmental Engineering; Oregon State University; 101 Covell Hall Corvallis OR 97331-2701
| | - Joshua B. Kitner
- Trillium FiberFuels, Inc.; 720 NE Granger Ave. Corvallis OR 97330-9660
| | | | - Jakob M. Townsend
- School of Chemical, Biological, and Environmental Engineering; Oregon State University; 101 Covell Hall Corvallis OR 97331-2701
| | | | - Christine J. Kelly
- School of Chemical, Biological, and Environmental Engineering; Oregon State University; 101 Covell Hall Corvallis OR 97331-2701
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Zheng Z, Lin X, Jiang T, Ye W, Ouyang J. Genomic analysis of a xylose operon and characterization of novel xylose isomerase and xylulokinase from Bacillus coagulans NL01. Biotechnol Lett 2016; 38:1331-9. [PMID: 27206341 DOI: 10.1007/s10529-016-2109-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/28/2016] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To investigate the xylose operon and properties of xylose isomerase and xylulokinase in Bacillus coagulans that can effectively ferment xylose to lactic acid. RESULTS The xylose operon is widely present in B. coagulans. It is composed of four putative ORFs. Novel xylA and xylB from B. coagulans NL01 were cloned and expressed in Escherichia coli. Sequence of xylose isomerase was more conserved than that of xylulokinase. Both the enzymes exhibited maximum activities at pH 7-8 but with a high temperature maximum of 80-85 °C, divalent metal ion was prerequisite for their activation. Xylose isomerase and xylulokinase were most effectively activated by Ni(2+) and Co(2+), respectively. CONCLUSIONS Genomic analysis of xylose operon has contributed to understanding xylose metabolism in B. coagulans and the novel xylose isomerase and xylulokinase might provide new alternatives for metabolic engineering of other strains to improve their fermentation performance on xylose.
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Affiliation(s)
- Zhaojuan Zheng
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.,Jiangsu Key Lab of Biomass-Based Green Fuels and Chemicals, Nanjing, 210037, People's Republic of China
| | - Xi Lin
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China
| | - Ting Jiang
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China
| | - Weihua Ye
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China
| | - Jia Ouyang
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China. .,Key Laboratory of Forest Genetics and Biotechnology of the Ministry of Education, Nanjing, 210037, People's Republic of China.
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12
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Waltman MJ, Yang ZK, Langan P, Graham DE, Kovalevsky A. Engineering acidic Streptomyces rubiginosus D-xylose isomerase by rational enzyme design. Protein Eng Des Sel 2014; 27:59-64. [PMID: 24402330 DOI: 10.1093/protein/gzt062] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To maximize bioethanol production from lignocellulosic biomass, all sugars must be utilized. Yeast fermentation can be improved by introducing the d-xylose isomerase enzyme to convert the pentose sugar d-xylose, which cannot be fermented by Saccharomyces cerevisiae, into the fermentable ketose d-xylulose. The low activity of d-xylose isomerase, especially at the low pH required for optimal fermentation, limits its use. A rational enzyme engineering approach was undertaken, and seven amino acid positions were replaced to improve the activity of Streptomyces rubiginosus d-xylose isomerase towards its physiological substrate at pH values below 6. The active-site design was guided by mechanistic insights and the knowledge of amino acid protonation states at low pH obtained from previous joint X-ray/neutron crystallographic experiments. Tagging the enzyme with 6 or 12 histidine residues at the N-terminus resulted in a significant increase in the active-site affinity towards substrate at pH 5.8. Substituting an asparagine at position 215, which hydrogen bonded to the metal-bound Glu181 and Asp245, with an aspartate gave a variant with almost an order of magnitude lower KM than measured for the native enzyme, with a 4-fold increase in activity. Other studied variants showed similar (Asp57Asn, Glu186Gln/Asn215Asp), lower (Asp57His, Asn247Asp, Lys289His, Lys289Glu) or no (Gln256Asp, Asp287Asn, ΔAsp287) activity in acidic conditions relative to the native enzyme.
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Affiliation(s)
- Mary Jo Waltman
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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Expression of Arabidopsis thaliana xylose isomerase gene and its effect on ethanol production in Flammulina velutipes. Fungal Biol 2013; 117:776-82. [PMID: 24295916 DOI: 10.1016/j.funbio.2013.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 09/04/2013] [Accepted: 09/30/2013] [Indexed: 11/21/2022]
Abstract
To improve the pentose fermentation rate in Flammulina velutipes, the putative xylose isomerase (XI) gene from Arabidopsis thaliana was cloned and introduced into F. velutipes and the gene expression was evaluated in transformants. mRNA expression of the putative XI gene and XI activity were observed in two transformants, indicating that the putative gene from A. thaliana was successfully expressed in F. velutipes as a xylose isomerase. In addition, ethanol production from xylose was increased in the recombinant strains. This is the first report demonstrating the possibility of using plant genes as candidates for improving the characteristics of F. velutipes.
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Demeke MM, Dietz H, Li Y, Foulquié-Moreno MR, Mutturi S, Deprez S, Den Abt T, Bonini BM, Liden G, Dumortier F, Verplaetse A, Boles E, Thevelein JM. Development of a D-xylose fermenting and inhibitor tolerant industrial Saccharomyces cerevisiae strain with high performance in lignocellulose hydrolysates using metabolic and evolutionary engineering. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:89. [PMID: 23800147 PMCID: PMC3698012 DOI: 10.1186/1754-6834-6-89] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 06/12/2013] [Indexed: 05/04/2023]
Abstract
BACKGROUND The production of bioethanol from lignocellulose hydrolysates requires a robust, D-xylose-fermenting and inhibitor-tolerant microorganism as catalyst. The purpose of the present work was to develop such a strain from a prime industrial yeast strain, Ethanol Red, used for bioethanol production. RESULTS An expression cassette containing 13 genes including Clostridium phytofermentans XylA, encoding D-xylose isomerase (XI), and enzymes of the pentose phosphate pathway was inserted in two copies in the genome of Ethanol Red. Subsequent EMS mutagenesis, genome shuffling and selection in D-xylose-enriched lignocellulose hydrolysate, followed by multiple rounds of evolutionary engineering in complex medium with D-xylose, gradually established efficient D-xylose fermentation. The best-performing strain, GS1.11-26, showed a maximum specific D-xylose consumption rate of 1.1 g/g DW/h in synthetic medium, with complete attenuation of 35 g/L D-xylose in about 17 h. In separate hydrolysis and fermentation of lignocellulose hydrolysates of Arundo donax (giant reed), spruce and a wheat straw/hay mixture, the maximum specific D-xylose consumption rate was 0.36, 0.23 and 1.1 g/g DW inoculum/h, and the final ethanol titer was 4.2, 3.9 and 5.8% (v/v), respectively. In simultaneous saccharification and fermentation of Arundo hydrolysate, GS1.11-26 produced 32% more ethanol than the parent strain Ethanol Red, due to efficient D-xylose utilization. The high D-xylose fermentation capacity was stable after extended growth in glucose. Cell extracts of strain GS1.11-26 displayed 17-fold higher XI activity compared to the parent strain, but overexpression of XI alone was not enough to establish D-xylose fermentation. The high D-xylose consumption rate was due to synergistic interaction between the high XI activity and one or more mutations in the genome. The GS1.11-26 had a partial respiratory defect causing a reduced aerobic growth rate. CONCLUSIONS An industrial yeast strain for bioethanol production with lignocellulose hydrolysates has been developed in the genetic background of a strain widely used for commercial bioethanol production. The strain uses glucose and D-xylose with high consumption rates and partial cofermentation in various lignocellulose hydrolysates with very high ethanol yield. The GS1.11-26 strain shows highly promising potential for further development of an all-round robust yeast strain for efficient fermentation of various lignocellulose hydrolysates.
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Affiliation(s)
- Mekonnen M Demeke
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven, Heverlee, Flanders, Belgium
| | - Heiko Dietz
- Institute of Molecular Biosciences, Goethe-University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany
| | - Yingying Li
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven, Heverlee, Flanders, Belgium
| | - María R Foulquié-Moreno
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven, Heverlee, Flanders, Belgium
| | - Sarma Mutturi
- Department of Chemical Engineering, Lund University, P.O. Box 124, 22100 Lund, Sweden
| | - Sylvie Deprez
- Laboratory of Enzyme, Fermentation and Brewing Technology, KAHO Sint-Lieven University College, KU Leuven Association, Gebroeders De Smetstraat 1, 9000, Ghent, Flanders, Belgium
| | - Tom Den Abt
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven, Heverlee, Flanders, Belgium
| | - Beatriz M Bonini
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven, Heverlee, Flanders, Belgium
| | - Gunnar Liden
- Department of Chemical Engineering, Lund University, P.O. Box 124, 22100 Lund, Sweden
| | - Françoise Dumortier
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven, Heverlee, Flanders, Belgium
| | - Alex Verplaetse
- Laboratory of Enzyme, Fermentation and Brewing Technology, KAHO Sint-Lieven University College, KU Leuven Association, Gebroeders De Smetstraat 1, 9000, Ghent, Flanders, Belgium
| | - Eckhard Boles
- Institute of Molecular Biosciences, Goethe-University Frankfurt, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany
| | - Johan M Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Belgium
- Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven, Heverlee, Flanders, Belgium
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An efficient xylose-fermenting recombinant Saccharomyces cerevisiae strain obtained through adaptive evolution and its global transcription profile. Appl Microbiol Biotechnol 2012; 96:1079-91. [PMID: 23053078 DOI: 10.1007/s00253-012-4418-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 08/25/2012] [Accepted: 08/29/2012] [Indexed: 10/27/2022]
Abstract
Factors related to ethanol production from xylose in engineered Saccharomyces cerevisiae that contain an exogenous initial metabolic pathway are still to be elucidated. In the present study, a strain that expresses the xylose isomerase gene of Piromyces sp. Pi-xylA and overexpresses XKS1, RPE1, RKI1, TAL1, and TKL1, with deleted GRE3 and COX4 genes was constructed. The xylose utilization capacity of the respiratory deficiency strain was poor but improved via adaptive evolution in xylose. The μ (max) of the evolved strain in 20 g l(-1) xylose is 0.11 ± 0.00 h(-1), and the evolved strain consumed 17.83 g l(-1) xylose within 72 h, with an ethanol yield of 0.43 g g(-1) total consumed sugars during glucose-xylose cofermentation. Global transcriptional changes and effect of several specific genes were studied. The result revealed that the increased xylose isomerase acivity, the upregulation of enzymes involved in glycolysis and glutamate synthesis, and the downregulation of trehalose and glycogen synthesis, may have contributed to the improved xylose utilization of the strain. Furthermore, the deletion of PHO13 decreased the xylose growth in the respiration deficiency strain although deleting PHO13 can improve the xylose metabolism in other strains.
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16
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Zhou H, Cheng JS, Wang BL, Fink GR, Stephanopoulos G. Xylose isomerase overexpression along with engineering of the pentose phosphate pathway and evolutionary engineering enable rapid xylose utilization and ethanol production by Saccharomyces cerevisiae. Metab Eng 2012; 14:611-22. [PMID: 22921355 DOI: 10.1016/j.ymben.2012.07.011] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 07/10/2012] [Accepted: 07/21/2012] [Indexed: 11/28/2022]
Abstract
Xylose is the main pentose and second most abundant sugar in lignocellulosic feedstocks. To improve xylose utilization, necessary for the cost-effective bioconversion of lignocellulose, several metabolic engineering approaches have been employed in the yeast Saccharomyces cerevisiae. In this study, we describe the rational metabolic engineering of a S. cerevisiae strain, including overexpression of the Piromyces xylose isomerase gene (XYLA), Pichia stipitis xylulose kinase (XYL3) and genes of the non-oxidative pentose phosphate pathway (PPP). This engineered strain (H131-A3) was used to initialize a three-stage process of evolutionary engineering, through first aerobic and anaerobic sequential batch cultivation followed by growth in a xylose-limited chemostat. The evolved strain H131-A3-AL(CS) displayed significantly increased anaerobic growth rate (0.203±0.006 h⁻¹) and xylose consumption rate (1.866 g g⁻¹ h⁻¹) along with high ethanol conversion yield (0.41 g/g). These figures exceed by a significant margin any other performance metrics on xylose utilization and ethanol production by S. cerevisiae reported to-date. Further inverse metabolic engineering based on functional complementation suggested that efficient xylose assimilation is attributed, in part, to the elevated expression level of xylose isomerase, which was accomplished through the multiple-copy integration of XYLA in the chromosome of the evolved strain.
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Affiliation(s)
- Hang Zhou
- Department of Chemical Engineering, Massachusetts Institute of Technology, Room 56-469, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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17
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Directed evolution of xylose isomerase for improved xylose catabolism and fermentation in the yeast Saccharomyces cerevisiae. Appl Environ Microbiol 2012; 78:5708-16. [PMID: 22685138 DOI: 10.1128/aem.01419-12] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The heterologous expression of a highly functional xylose isomerase pathway in Saccharomyces cerevisiae would have significant advantages for ethanol yield, since the pathway bypasses cofactor requirements found in the traditionally used oxidoreductase pathways. However, nearly all reported xylose isomerase-based pathways in S. cerevisiae suffer from poor ethanol productivity, low xylose consumption rates, and poor cell growth compared with an oxidoreductase pathway and, additionally, often require adaptive strain evolution. Here, we report on the directed evolution of the Piromyces sp. xylose isomerase (encoded by xylA) for use in yeast. After three rounds of mutagenesis and growth-based screening, we isolated a variant containing six mutations (E15D, E114G, E129D, T142S, A177T, and V433I) that exhibited a 77% increase in enzymatic activity. When expressed in a minimally engineered yeast host containing a gre3 knockout and tal1 and XKS1 overexpression, the strain expressing this mutant enzyme improved its aerobic growth rate by 61-fold and both ethanol production and xylose consumption rates by nearly 8-fold. Moreover, the mutant enzyme enabled ethanol production by these yeasts under oxygen-limited fermentation conditions, unlike the wild-type enzyme. Under microaerobic conditions, the ethanol production rates of the strain expressing the mutant xylose isomerase were considerably higher than previously reported values for yeast harboring a xylose isomerase pathway and were also comparable to those of the strains harboring an oxidoreductase pathway. Consequently, this study shows the potential to evolve a xylose isomerase pathway for more efficient xylose utilization.
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18
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Toteva MM, Silvaggi NR, Allen KN, Richard JP. Binding energy and catalysis by D-xylose isomerase: kinetic, product, and X-ray crystallographic analysis of enzyme-catalyzed isomerization of (R)-glyceraldehyde. Biochemistry 2011; 50:10170-81. [PMID: 21995300 DOI: 10.1021/bi201378c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
D-Xylose isomerase (XI) and triosephosphate isomerase (TIM) catalyze the aldose-ketose isomerization reactions of D-xylose and d-glyceraldehyde 3-phosphate (DGAP), respectively. D-Glyceraldehyde (DGA) is the triose fragment common to the substrates for XI and TIM. The XI-catalyzed isomerization of DGA to give dihydroxyacetone (DHA) in D(2)O was monitored by (1)H nuclear magnetic resonance spectroscopy, and a k(cat)/K(m) of 0.034 M(-1) s(-1) was determined for this isomerization at pD 7.0. This is similar to the k(cat)/K(m) of 0.017 M(-1) s(-1) for the TIM-catalyzed carbon deprotonation reaction of DGA in D(2)O at pD 7.0 [Amyes, T. L., O'Donoghue, A. C., and Richard, J. P. (2001) J. Am. Chem. Soc. 123, 11325-11326]. The much larger activation barrier for XI-catalyzed isomerization of D-xylose (k(cat)/K(m) = 490 M(-1) s(-1)) versus that for the TIM-catalyzed isomerization of DGAP (k(cat)/K(m) = 9.6 × 10(6) M(-1) s(-1)) is due to (i) the barrier to conversion of cyclic d-xylose to the reactive linear sugar (5.4 kcal/mol) being larger than that for conversion of DGAP hydrate to the free aldehyde (1.7 kcal/mol) and (ii) the intrinsic binding energy [Jencks, W. P. (1975) Adv. Enzymol. Relat. Areas Mol. Biol. 43, 219-410] of the terminal ethylene glycol fragment of D-xylose (9.3 kcal/mol) being smaller than that of the phosphodianion group of DGAP (~12 kcal/mol). The XI-catalyzed isomerization of DGA in D(2)O at pD 7.0 gives a 90% yield of [1-(1)H]DHA and a 10% yield of [1-(2)H]DHA, the product of isomerization with incorporation of deuterium from solvent D(2)O. By comparison, the transfer of (3)H from the labeled hexose substrate to solvent is observed only once in every 10(9) turnovers for the XI-catalyzed isomerization of [2-(3)H]glucose in H(2)O [Allen, K. N., Lavie, A., Farber, G. K., Glasfeld, A., Petsko, G. A., and Ringe, D. (1994) Biochemistry 33, 1481-1487]. We propose that truncation of the terminal ethylene glycol fragment of d-xylose to give DGA results in a large decrease in the rate of XI-catalyzed isomerization with hydride transfer compared with that for proton transfer. An ultra-high-resolution (0.97 Å) X-ray crystal structure was determined for the complex obtained by soaking crystals of XI with 50 mM DGA. The triose binds to XI as the unreactive hydrate, but ligand binding induces metal cofactor movement and conformational changes in active site residues similar to those observed for XI·sugar complexes.
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Affiliation(s)
- Maria M Toteva
- Department of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, USA
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19
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Xylitol does not inhibit xylose fermentation by engineered Saccharomyces cerevisiae expressing xylA as severely as it inhibits xylose isomerase reaction in vitro. Appl Microbiol Biotechnol 2011; 92:77-84. [PMID: 21655987 DOI: 10.1007/s00253-011-3345-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/13/2011] [Accepted: 04/18/2011] [Indexed: 10/18/2022]
Abstract
Efficient fermentation of xylose, which is abundant in hydrolysates of lignocellulosic biomass, is essential for producing cellulosic biofuels economically. While heterologous expression of xylose isomerase in Saccharomyces cerevisiae has been proposed as a strategy to engineer this yeast for xylose fermentation, only a few xylose isomerase genes from fungi and bacteria have been functionally expressed in S. cerevisiae. We cloned two bacterial xylose isomerase genes from anaerobic bacteria (Bacteroides stercoris HJ-15 and Bifidobacterium longum MG1) and introduced them into S. cerevisiae. While the transformant with xylA from B. longum could not assimilate xylose, the transformant with xylA from B. stercoris was able to grow on xylose. This result suggests that the xylose isomerase (BsXI) from B. stercoris is functionally expressed in S. cerevisiae. The engineered S. cerevisiae strain with BsXI consumed xylose and produced ethanol with a good yield (0.31 g/g) under anaerobic conditions. Interestingly, significant amounts of xylitol (0.23 g xylitol/g xylose) were still accumulated during xylose fermentation even though the introduced BsXI might not cause redox imbalance. We investigated the potential inhibitory effects of the accumulated xylitol on xylose fermentation. Although xylitol inhibited in vitro BsXI activity significantly (K(I) = 5.1 ± 1.15 mM), only small decreases (less than 10%) in xylose consumption and ethanol production rates were observed when xylitol was added into the fermentation medium. These results suggest that xylitol accumulation does not inhibit xylose fermentation by engineered S. cerevisiae expressing xylA as severely as it inhibits the xylose isomerase reaction in vitro.
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20
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Xu W, Yan M, Xu L, Ding L, Ouyang P. Engineering the activity of thermophilic xylose isomerase by site-directed mutation at subunit interfaces. Enzyme Microb Technol 2009. [DOI: 10.1016/j.enzmictec.2008.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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21
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Kuyper M, Harhangi HR, Stave AK, Winkler AA, Jetten MSM, de Laat WTAM, den Ridder JJJ, Op den Camp HJM, van Dijken JP, Pronk JT. High-level functional expression of a fungal xylose isomerase: the key to efficient ethanolic fermentation of xylose by Saccharomyces cerevisiae? FEMS Yeast Res 2004; 4:69-78. [PMID: 14554198 DOI: 10.1016/s1567-1356(03)00141-7] [Citation(s) in RCA: 233] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Evidence is presented that xylose metabolism in the anaerobic cellulolytic fungus Piromyces sp. E2 proceeds via a xylose isomerase rather than via the xylose reductase/xylitol-dehydrogenase pathway found in xylose-metabolising yeasts. The XylA gene encoding the Piromyces xylose isomerase was functionally expressed in Saccharomyces cerevisiae. Heterologous isomerase activities in cell extracts, assayed at 30 degrees C, were 0.3-1.1 micromol min(-1) (mg protein)(-1), with a Km for xylose of 20 mM. The engineered S. cerevisiae strain grew very slowly on xylose. It co-consumed xylose in aerobic and anaerobic glucose-limited chemostat cultures at rates of 0.33 and 0.73 mmol (g biomass)(-1) h(-1), respectively.
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Affiliation(s)
- Marko Kuyper
- Kluyver Laboratory of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
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23
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Whitaker RD, Cho Y, Cha J, Carrell HL, Glusker JP, Karplus PA, Batt CA. Probing the roles of active site residues in D-xylose isomerase. J Biol Chem 1995; 270:22895-906. [PMID: 7559425 DOI: 10.1074/jbc.270.39.22895] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The roles of active site residues His54, Phe94, Lys183, and His220 in the Streptomyces rubiginosus D-xylose isomerase were probed by site-directed mutagenesis. The kinetic properties and crystal structures of the mutant enzymes were characterized. The pH dependence of diethylpyrocarbonate modification of His54 suggests that His54 does not catalyze ring-opening as a general acid. His54 appears to be involved in anomeric selection and stabilization of the acyclic transition state by hydrogen bonding. Phe94 stabilizes the acyclic-extended transition state directly by hydrophobic interactions and/or indirectly by interactions with Trp137 and Phe26. Lys183 and His220 mutants have little or no activity and the structures of these mutants with D-xylose reveal cyclic alpha-D-xylopyranose. Lys183 functions structurally by maintaining the position of Pro187 and Glu186 and catalytically by interacting with acyclic-extended sugars. His220 provides structure for the M2-metal binding site with properties which are necessary for extension and isomerization of the substrate. A second M2 metal binding site (M2') is observed at a relatively lower occupancy when substrate is added consistent with the hypothesis that the metal moves as the hydride is shifted on the extended substrate.
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Affiliation(s)
- R D Whitaker
- Department of Food Science, Cornell University, Ithaca, New York 14853, USA
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Jenkins J, Janin J, Rey F, Chiadmi M, van Tilbeurgh H, Lasters I, De Maeyer M, Van Belle D, Wodak SJ, Lauwereys M. Protein engineering of xylose (glucose) isomerase from Actinoplanes missouriensis. 1. Crystallography and site-directed mutagenesis of metal binding sites. Biochemistry 1992; 31:5449-58. [PMID: 1610791 DOI: 10.1021/bi00139a005] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The structure and function of the xylose (glucose) isomerase from Actinoplanes missouriensis have been analyzed by X-ray crystallography and site-directed mutagenesis after cloning and overexpression in Escherichia coli. The crystal structure of wild-type enzyme has been refined to an R factor of 15.2% against diffraction data to 2.2-A resolution. The structures of a number of binary and ternary complexes involving wild-type and mutant enzymes, the divalent cations Mg2+, Co2+, or Mn2+, and either the substrate xylose or substrate analogs have also been determined and refined to comparable R factors. Two metal sites are identified. Metal site 1 is four-coordinated and tetrahedral in the absence of substrate and is six-coordinated and octahedral in its presence; the O2 and O4 atoms of linear inhibitors and substrate bind to metal 1. Metal site 2 is octahedral in all cases; its position changes by 0.7 A when it binds O1 of the substrate and by more than 1 A when it also binds O2; these bonds replace bonds to carboxylate ligands from the protein. Side chains involved in metal binding have been substituted by site-directed mutagenesis. The biochemical properties of the mutant enzymes are presented. Together with structural data, they demonstrate that the two metal ions play an essential part in binding substrates, in stabilizing their open form, and in catalyzing hydride transfer between the C1 and C2 positions.
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Affiliation(s)
- J Jenkins
- Laboratoire de Biologie Physicochimique, CNRS UA1131, Université Paris-Sud, Orsay, France
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van Tilbeurgh H, Jenkins J, Chiadmi M, Janin J, Wodak SJ, Mrabet NT, Lambeir AM. Protein engineering of xylose (glucose) isomerase from Actinoplanes missouriensis. 3. Changing metal specificity and the pH profile by site-directed mutagenesis. Biochemistry 1992; 31:5467-71. [PMID: 1610793 DOI: 10.1021/bi00139a007] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Aldose-ketose isomerization by xylose isomerase requires bivalent cations such as Mg2+, Mn2+, or Co2+. The active site of the enzyme from Actinoplanes missouriensis contains two metal ions that are involved in substrate binding and in catalyzing a hydride shift between the C1 and C2 substrate atoms. Glu 186 is a conserved residue located near the active site but not in contact with the substrate and not with a metal ligand. The E186D and E186Q mutant enzymes were prepared. Both are active, and their metal specificity is different from that of the wild type. The E186Q enzyme is most active with Mn2+ and has a drastically shifted pH optimum. The X-ray analysis of E186Q was performed in the presence of xylose and either Mn2+ or Mg2+. The Mn2+ structure is essentially identical to that of the wild type. In the presence of Mg2+, the carboxylate group of residue Asp 255, which is part of metal site 2 and a metal ligand, turns toward Gln 186 and hydrogen bonds to its side-chain amide. Mg2+ is not bound at metal site 2, explaining the low activity of the mutant with this cation. Movements of Asp 255 also occur in the wild-type enzyme. We propose that they play a role in the O1 to O2 proton relay accompanying the hydride shift.
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Callens M, Kersters-Hilderson H, Vangrysperre W, De Bruyne CK. d-Xylose isomerase from Streptomyces violaceoruber: Structural and catalytic roles of bivalent metal ions. Enzyme Microb Technol 1988. [DOI: 10.1016/0141-0229(88)90064-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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A flow-injection system for the amperometric determination of xylose and xylulose with co-immobilized enzymes and a modified electrode. Anal Chim Acta 1988. [DOI: 10.1016/s0003-2670(00)81348-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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