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Agrawal A, Bandi CK, Burgin T, Woo Y, Mayes HB, Chundawat SPS. Click-Chemistry-Based Free Azide versus Azido Sugar Detection Enables Rapid In Vivo Screening of Glycosynthase Activity. ACS Chem Biol 2021; 16:2490-2501. [PMID: 34499469 DOI: 10.1021/acschembio.1c00585] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Engineering of carbohydrate-active enzymes such as glycosynthases to enable chemoenzymatic synthesis of bespoke oligosaccharides has been limited by the lack of suitable ultrahigh-throughput screening methods capable of robustly detecting either starting substrates or end-products of the glycosidic bond formation reaction. Currently, there are limited screening methods available for rapid and highly sensitive single-cell-based screening of glycosynthase enzymes employing azido sugars as activated donor glycosyl substrates. Here, we report a fluorescence-based approach employing click-chemistry for the selective detection of glycosyl azides as substrates versus free inorganic azides as reaction products that facilitated an ultrahigh-throughput in vivo single-cell-based assay of glycosynthase activity. This assay was developed based on the distinct differences observed in relative fluorescence intensity of the triazole-containing fluorophore product formed during the click-chemistry reaction of organic glycosyl azides versus inorganic azides. This discovery formed the basis for proof of concept validation of a directed evolution methodology for screening and sorting glycosynthase mutants capable of synthesis of targeted fucosylated oligosaccharides. Our screening approach facilitated fluorescence-activated cell sorting of an error-prone polymerase chain reaction-based mutant library of fucosynthases expressed in Escherichia coli to identify several novel mutants that showed increased activity for β-fucosyl azide-activated donor sugars toward desired acceptor sugars (e.g., pNP-xylose and lactose). Finally, we discuss avenues for improving this proof of concept in vivo assay method to identify better glycosynthase mutants and further demonstrate the broader applicability of this screening methodology for synthesis of bespoke glycans.
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Affiliation(s)
- Ayushi Agrawal
- Department of Chemical & Biochemical Engineering, Rutgers The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, United States
| | - Chandra Kanth Bandi
- Department of Chemical & Biochemical Engineering, Rutgers The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, United States
| | - Tucker Burgin
- Department of Chemical Engineering, University of Michigan Ann Arbor, 2800 Plymouth Avenue, Ann Arbor, Michigan 48105, United States
| | - Youngwoo Woo
- Department of Chemical Engineering, University of Michigan Ann Arbor, 2800 Plymouth Avenue, Ann Arbor, Michigan 48105, United States
| | - Heather B. Mayes
- Department of Chemical Engineering, University of Michigan Ann Arbor, 2800 Plymouth Avenue, Ann Arbor, Michigan 48105, United States
- National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Shishir P. S. Chundawat
- Department of Chemical & Biochemical Engineering, Rutgers The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, United States
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Kurgan G, Onyeabor M, Holland SC, Taylor E, Schneider A, Kurgan L, Billings T, Wang X. Directed evolution of Zymomonas mobilis sugar facilitator Glf to overcome glucose inhibition. J Ind Microbiol Biotechnol 2021; 49:6371102. [PMID: 34529081 PMCID: PMC9118996 DOI: 10.1093/jimb/kuab066] [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: 06/22/2021] [Accepted: 09/04/2021] [Indexed: 12/01/2022]
Abstract
Cellular import of D-xylose, the second most abundant sugar in typical lignocellulosic biomass, has been evidenced to be an energy-depriving process in bacterial biocatalysts. The sugar facilitator of Zymomonas mobilis, Glf, is capable of importing xylose at high rates without extra energy input, but is inhibited by D-glucose (the primary biomass sugar), potentially limiting the utility of this transporter for fermentation of sugar mixtures derived from lignocellulose. In this work we developed an Escherichia coli platform strain deficient in glucose and xylose transport to facilitate directed evolution of Glf to overcome glucose inhibition. Using this platform, we isolated nine Glf variants created by both random and site-saturation mutagenesis with increased xylose utilization rates ranging from 4.8-fold to 13-fold relative to wild-type Glf when fermenting 100 g l–1 glucose–xylose mixtures. Diverse point mutations such as A165M and L445I were discovered leading to released glucose inhibition. Most of these mutations likely alter sugar coordinating pocket for the 6-hydroxymethyl group of D-glucose. These discovered glucose-resistant Glf variants can be potentially used as energy-conservative alternatives to the native sugar transport systems of bacterial biocatalysts for fermentation of lignocellulose-derived sugars.
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Affiliation(s)
- Gavin Kurgan
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Moses Onyeabor
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Steven C Holland
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Eric Taylor
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Aidan Schneider
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Logan Kurgan
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Tommy Billings
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Xuan Wang
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
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Wang L, York SW, Ingram LO, Shanmugam KT. Simultaneous fermentation of biomass-derived sugars to ethanol by a co-culture of an engineered Escherichia coli and Saccharomyces cerevisiae. BIORESOURCE TECHNOLOGY 2019; 273:269-276. [PMID: 30448678 DOI: 10.1016/j.biortech.2018.11.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/04/2018] [Accepted: 11/05/2018] [Indexed: 06/09/2023]
Abstract
Microorganisms ferment xylose at high rate only when glucose concentration in the medium falls below a critical level. Since the specific productivity of product is highest during exponential to early stationary phase of growth, a glucose utilization negative ethanologenic E. coli (strain LW419a) was constructed for high rate of xylose fermentation in combination with Turbo yeast. This co-culture fermented all the released sugars in an acid/enzyme-treated sugar cane bagasse slurry (10% solids) to an ethanol titer of 24.9 ± 0.8 g.L-1 (70% of the theoretical yield) in <30 h. Ethanol titer increased to 48.6 ± 1.04 g.L-1 (yield, 0.45 g.g-1 sugars) at a solids content of 20% and the highest rate of xylose consumption was 1.58 ± 0.21 g.L-1.h-1. This study demonstrates the potential of a co-culture of strain LW419a and yeast to rapidly ferment all the sugars in pretreated biomass slurries to ethanol at their respective highest rates.
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Affiliation(s)
- Liang Wang
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, United States.
| | - Sean W York
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, United States.
| | - Lonnie O Ingram
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, United States.
| | - K T Shanmugam
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, United States.
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Behera S, Sharma NK, Arora R, Kumar S. Effect of Evolutionary Adaption on Xylosidase Activity in Thermotolerant Yeast Isolates Kluyveromyces marxianus NIRE-K1 and NIRE-K3. Appl Biochem Biotechnol 2016; 179:1143-54. [DOI: 10.1007/s12010-016-2055-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 03/15/2016] [Indexed: 02/02/2023]
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Ranade S, Zhang Y, Kaplan M, Majeed W, He Q. Metabolic Engineering and Comparative Performance Studies of Synechocystis sp. PCC 6803 Strains for Effective Utilization of Xylose. Front Microbiol 2015; 6:1484. [PMID: 26732758 PMCID: PMC4689873 DOI: 10.3389/fmicb.2015.01484] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/09/2015] [Indexed: 01/16/2023] Open
Abstract
Wood sugars such as xylose can be used as an inexpensive carbon source for biotechnological applications. The model cyanobacterium Synechocystis sp. PCC 6803 lacks the ability to catabolize wood sugars as an energy source. Here, we generated four Synechocystis strains that heterologously expressed XylAB enzymes, which mediate xylose catabolism, either in combination with or without one of three xylose transporters, namely XylE, GalP, or Glf. Except for glf, which is derived from the bacterium Zymomonas mobilis ZM4, the heterologous genes were sourced from Escherichia coli K-12. All of the recombinant strains were able to utilize xylose in the absence of catabolite repression. When xylose was the lone source of organic carbon, strains possessing the XylE and Glf transporters were most efficient in terms of dry biomass production and xylose consumption and the strain lacking a heterologous transporter was the least efficient. However, in the presence of a xylose-glucose mixed sugar source, the strains exhibited similar levels of growth and xylose consumption. This study demonstrates that various bacterial xylose transporters can boost xylose catabolism in transgenic Synechocystis strains, and paves the way for the sustainable production of bio-compounds and green fuels from lignocellulosic biomass.
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Affiliation(s)
- Saurabh Ranade
- Department of Biology, University of Arkansas at Little Rock Little Rock, AR, USA
| | - Yan Zhang
- Biotechnology Research Center, Shandong Academy of Agricultural Sciences Jinan, China
| | - Mecit Kaplan
- Department of Biology, University of Arkansas at Little Rock Little Rock, AR, USA
| | - Waqar Majeed
- Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock Little Rock, AR, USA
| | - Qingfang He
- Department of Biology, University of Arkansas at Little Rock Little Rock, AR, USA
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An assay for functional xylose transporters in Saccharomyces cerevisiae. Anal Biochem 2013; 442:241-8. [DOI: 10.1016/j.ab.2013.07.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 07/27/2013] [Accepted: 07/29/2013] [Indexed: 11/18/2022]
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Zhou B, Xing L, Wu W, Zhang XE, Lin Z. Small surfactant-like peptides can drive soluble proteins into active aggregates. Microb Cell Fact 2012; 11:10. [PMID: 22251949 PMCID: PMC3398302 DOI: 10.1186/1475-2859-11-10] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 01/18/2012] [Indexed: 11/20/2022] Open
Abstract
Background Inactive protein inclusion bodies occur commonly in Escherichia coli (E. coli) cells expressing heterologous proteins. Previously several independent groups have found that active protein aggregates or pseudo inclusion bodies can be induced by a fusion partner such as a cellulose binding domain from Clostridium cellulovorans (CBDclos) when expressed in E. coli. More recently we further showed that a short amphipathic helical octadecapeptide 18A (EWLKAFYEKVLEKLKELF) and a short beta structure peptide ELK16 (LELELKLKLELELKLK) have a similar property. Results In this work, we explored a third type of peptides, surfactant-like peptides, for performing such a "pulling-down" function. One or more of three such peptides (L6KD, L6K2, DKL6) were fused to the carboxyl termini of model proteins including Aspergillus fumigatus amadoriase II (AMA, all three peptides were used), Bacillus subtilis lipase A (LipA, only L6KD was used, hereinafter the same), Bacillus pumilus xylosidase (XynB), and green fluorescent protein (GFP), and expressed in E. coli. All fusions were found to predominantly accumulate in the insoluble fractions, with specific activities ranging from 25% to 92% of the native counterparts. Transmission electron microscopic (TEM) and confocal fluorescence microscopic analyses confirmed the formation of protein aggregates in the cell. Furthermore, binding assays with amyloid-specific dyes (thioflavin T and Cong red) to the AMA-L6KD aggregate and the TEM analysis of the aggregate following digestion with protease K suggested that the AMA-L6KD aggregate may contain structures reminiscent of amyloids, including a fibril-like structure core. Conclusions This study shows that the surfactant-like peptides L6KD and it derivatives can act as a pull-down handler for converting soluble proteins into active aggregates, much like 18A and ELK16. These peptide-mediated protein aggregations might have important implications for protein aggregation in vivo, and can be explored for production of functional biopolymers with detergent or other interfacial activities.
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Affiliation(s)
- Bihong Zhou
- Department of Chemical Engineering, Tsinghua University, One Tsinghua Garden Road, Beijing 100084, China
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Wu W, Xing L, Zhou B, Lin Z. Active protein aggregates induced by terminally attached self-assembling peptide ELK16 in Escherichia coli. Microb Cell Fact 2011; 10:9. [PMID: 21320350 PMCID: PMC3045283 DOI: 10.1186/1475-2859-10-9] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 02/15/2011] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND In recent years, it has been gradually realized that bacterial inclusion bodies (IBs) could be biologically active. In particular, several proteins including green fluorescent protein, β-galactosidase, β-lactamase, alkaline phosphatase, D-amino acid oxidase, polyphosphate kinase 3, maltodextrin phosphorylase, and sialic acid aldolase have been successfully produced as active IBs when fused to an appropriate partner such as the foot-and-mouth disease virus capsid protein VP1, or the human β-amyloid peptide Aβ42(F19D). As active IBs may have many attractive advantages in enzyme production and industrial applications, it is of considerable interest to explore them further. RESULTS In this paper, we report that an ionic self-assembling peptide ELK16 (LELELKLK)2 was able to effectively induce the formation of cytoplasmic inclusion bodies in Escherichia coli (E. coli) when attached to the carboxyl termini of four model proteins including lipase A, amadoriase II, β-xylosidase, and green fluorescent protein. These aggregates had a general appearance similar to the usually reported cytoplasmic inclusion bodies (IBs) under transmission electron microscopy or fluorescence confocal microscopy. Except for lipase A-ELK16 fusion, the three other fusion protein aggregates retained comparable specific activities with the native counterparts. Conformational analyses by Fourier transform infrared spectroscopy revealed the existence of newly formed antiparallel beta-sheet structures in these ELK16 peptide-induced inclusion bodies, which is consistent with the reported assembly of the ELK16 peptide. CONCLUSIONS This has been the first report where a terminally attached self-assembling β peptide ELK16 can promote the formation of active inclusion bodies or active protein aggregates in E. coli. It has the potential to render E. coli and other recombinant hosts more efficient as microbial cell factories for protein production. Our observation might also provide hints for protein aggregation-related diseases.
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Affiliation(s)
- Wei Wu
- Department of Chemical Engineering, Tsinghua University, One Tsinghua Garden Road, Beijing 100084, PR China
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Fu J, Wang S. Insights into auxin signaling in plant-pathogen interactions. FRONTIERS IN PLANT SCIENCE 2011; 2:74. [PMID: 22639609 PMCID: PMC3355572 DOI: 10.3389/fpls.2011.00074] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 10/17/2011] [Indexed: 05/17/2023]
Abstract
The phytohormone auxin has been known to be a regulator of plant growth and development ever since its discovery. Recent studies on plant-pathogen interactions identify auxin as a key character in pathogenesis and plant defense. Like plants, diverse pathogens possess the capacity to synthesize indole-3-acetic acid (IAA), the major form of auxin in plants. The emerging knowledge on auxin-signaling components, auxin metabolic processes, and indole-derived phytoalexins in plant responses to pathogen invasion has provided putative mechanisms of IAA in plant susceptibility and resistance to non-gall- or tumor-inducing pathogens.
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Affiliation(s)
- Jing Fu
- College of Life Sciences, Northwest A&F UniversityYangling, China
| | - Shiping Wang
- National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural UniversityWuhan, China
- *Correspondence: Shiping Wang, National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China. e-mail:
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Sugar transporters in efficient utilization of mixed sugar substrates: current knowledge and outlook. Appl Microbiol Biotechnol 2010; 85:471-80. [PMID: 19838697 DOI: 10.1007/s00253-009-2292-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 10/02/2009] [Accepted: 10/03/2009] [Indexed: 01/04/2023]
Abstract
There is increasing interest in production of transportation fuels and commodity chemicals from lignocellulosic biomass, most desirably through biological fermentation. Considerable effort has been expended to develop efficient biocatalysts that convert sugars derived from lignocellulose directly to value-added products. Glucose, the building block of cellulose, is the most suitable fermentation substrate for industrial microorganisms such as Escherichia coli, Corynebacterium glutamicum, and Saccharomyces cerevisiae. Other sugars including xylose, arabinose, mannose, and galactose that comprise hemicellulose are generally less efficient substrates in terms of productivity and yield. Although metabolic engineering including introduction of functional pentose-metabolizing pathways into pentose-incompetent microorganisms has provided steady progress in pentose utilization, further improvements in sugar mixture utilization by microorganisms is necessary. Among a variety of issues on utilization of sugar mixtures by the microorganisms, recent studies have started to reveal the importance of sugar transporters in microbial fermentation performance. In this article, we review current knowledge on diversity and functions of sugar transporters, especially those associated with pentose uptake in microorganisms. Subsequently, we review and discuss recent studies on engineering of sugar transport as a driving force for efficient bioconversion of sugar mixtures derived from lignocellulose.
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An evolved xylose transporter from Zymomonas mobilis enhances sugar transport in Escherichia coli. Microb Cell Fact 2009; 8:66. [PMID: 20003468 PMCID: PMC2801659 DOI: 10.1186/1475-2859-8-66] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2009] [Accepted: 12/15/2009] [Indexed: 11/24/2022] Open
Abstract
Background Xylose is a second most abundant sugar component of lignocellulose besides glucose. Efficient fermentation of xylose is important for the economics of biomass-based biorefineries. However, sugar mixtures are sequentially consumed in xylose co-fermentation with glucose due to carbon catabolite repression (CCR) in microorganisms. As xylose transmembrance transport is one of the steps repressed by CCR, it is therefore of interest to develop a transporter that is less sensitive to the glucose inhibition or CCR. Results The glucose facilitator protein Glf transporter from Zymomonas mobilis, also an efficient transporter for xylose, was chosen as the target transporter for engineering to eliminate glucose inhibition on xylose uptake. The evolution of Glf transporter was carried out with a mixture of glucose and xylose in E. coli. Error-prone PCR and random deletion were employed respectively in two rounds of evolution. Aided by a high-throughput screening assay using xylose analog p-nitrophenyl-β-D-xylopyranoside (pNPX) in 96-well plates, a best mutant 2-RD5 was obtained that contains several mutations, and a deletion of 134 residues (about 28% of total residues), or three fewer transmembrane sections (TMSs). It showed a 10.8-fold improvement in terms of pNPX transport activity in the presence of glucose. The fermentation performance results showed that this mutant improved xylose consumption by 42% with M9 minimal medium containing 20 g L-1 xylose only, while with the mixture sugar of xylose and glucose, 28% more glucose was consumed, but no obvious co-utilization of xylose was observed. Further glucose fed-batch experiments suggested that the intracellular metabolism of xylose was repressed by glucose. Conclusions Through random mutagenesis and partial deletion coupled with high-throughput screening, a mutant of the Glf transporter (2-RD5) was obtained that relieved the inhibition of xylose transport by glucose. The fermentation tests revealed that 2-RD5 was advantageous in xylose and glucose uptakes, while no obvious advantage was seen for xylose co-consumption when co-fermented with glucose. Further efforts could focus on reducing CCR-mediated repression of intracellular metabolism of xylose. Glf should also serve as a useful model to further exploit the molecular mechanism of xylose transport and the CCR-mediated inhibition.
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