251
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Jalak J, Kurašin M, Teugjas H, Väljamäe P. Endo-exo synergism in cellulose hydrolysis revisited. J Biol Chem 2012; 287:28802-15. [PMID: 22733813 DOI: 10.1074/jbc.m112.381624] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Synergistic cooperation of different enzymes is a prerequisite for efficient degradation of cellulose. The conventional mechanistic interpretation of the synergism between randomly acting endoglucanases (EGs) and chain end-specific processive cellobiohydrolases (CBHs) is that EG-generated new chain ends on cellulose surface serve as starting points for CBHs. Here we studied the hydrolysis of bacterial cellulose (BC) by CBH TrCel7A and EG TrCel5A from Trichoderma reesei under both single-turnover and "steady state" conditions. Unaccountable by conventional interpretation, the presence of EG increased the rate constant of TrCel7A-catalyzed hydrolysis of BC in steady state. At optimal enzyme/substrate ratios, the "steady state" rate of synergistic hydrolysis became limited by the velocity of processive movement of TrCel7A on BC. A processivity value of 66 ± 7 cellobiose units measured for TrCel7A on (14)C-labeled BC was close to the leveling off degree of polymerization of BC, suggesting that TrCel7A cannot pass through the amorphous regions on BC and stalls. We propose a mechanism of endo-exo synergism whereby the degradation of amorphous regions by EG avoids the stalling of TrCel7A and leads to its accelerated recruitment. Hydrolysis of pretreated wheat straw suggested that this mechanism of synergism is operative also in the degradation of lignocellulose. Although both mechanisms of synergism are used in parallel, the contribution of conventional mechanism is significant only at high enzyme/substrate ratios.
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Affiliation(s)
- Jürgen Jalak
- Institute of Molecular and Cell Biology, University of Tartu, Vanemuise 46-138, 51014 Tartu, Estonia
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252
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Gómez C, Horna DH, Olano C, Méndez C, Salas JA. Participation of putative glycoside hydrolases SlgC1 and SlgC2 in the biosynthesis of streptolydigin in Streptomyces lydicus. Microb Biotechnol 2012; 5:663-7. [PMID: 22726958 PMCID: PMC3815878 DOI: 10.1111/j.1751-7915.2012.00352.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 04/27/2012] [Accepted: 05/03/2012] [Indexed: 11/28/2022] Open
Abstract
Two genes of the streptolydigin gene cluster in Streptomyces lydicus cluster encode putative family 16 glycoside hydrolases. Both genes are expressed when streptolydigin is produced. Inactivation of these genes affects streptolydigin production when the microorganism is grown in minimal medium containing either glycerol or d-glucans as carbon source. Streptolydigin yields in S. lydicus were increased by overexpression of either slgC1 or slgC2.
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Affiliation(s)
- Cristina Gómez
- Departamento de Biología Funcional, Universidad de Oviedo, 33006, Oviedo, Spain
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253
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Rodríguez-Gacio MDC, Iglesias-Fernández R, Carbonero P, Matilla AJ. Softening-up mannan-rich cell walls. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:3976-88. [PMID: 22553284 DOI: 10.1093/jxb/ers096] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The softening and degradation of the cell wall (CW), often mannan enriched, is involved in several processes during development of higher plants, such as meristematic growth, fruit ripening, programmed cell death, and endosperm rupture upon germination. Mannans are also the predominant hemicellulosic CW polymers in many genera of green algae. The endosperm CWs of dry seeds often contain mannan polymers, sometimes in the form of galactomannans (Gal-mannans). The endo-β-mannanases (MANs) that catalyse the random hydrolysis of the β-linkage in the mannan backbone are one of the main hydrolytic enzymes involved in the loosening and remodelling of CWs. In germinating seeds, the softening of the endosperm seed CWs facilitates the emergence of the elongating radicle. Hydrolysis and mobilization of endosperm Gal-mannans by MANs also provides a source of nutrients for early seedling growth, since Gal-mannan, besides its structural role, serves as a storage polysaccharide. Therefore, the role of mannans and of their hydrolytic enzymes is decisive in the life cycle of seeds. This review updates and discusses the significance of mannans and MANs in seeds and explores the increasing biotechnological potential of MAN enzymes.
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254
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Ahmad A, Anjum FM, Zahoor T, Nawaz H, Dilshad SMR. Beta glucan: a valuable functional ingredient in foods. Crit Rev Food Sci Nutr 2012; 52:201-12. [PMID: 22214441 DOI: 10.1080/10408398.2010.499806] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
β-Glucan is a valuable functional ingredient and various extraction techniques are available for its extraction. Choice of an appropriate extraction technique is important as it may affect the quality, structure, rheological properties, molecular weight, and other functional properties of the extracted β-glucan. These properties lead to the use of β-glucan into various food systems and have important implications in human health. This review focuses on the extraction, synthesis, structure, molecular weight, and rheology of β-glucan. Furthermore, health implications and utilization of β-glucan in food products is also discussed.
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Affiliation(s)
- Asif Ahmad
- Department of Food Technology, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan.
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255
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Biomass Converting Enzymes as Industrial Biocatalysts for Fuels and Chemicals: Recent Developments. Catalysts 2012. [DOI: 10.3390/catal2020244] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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256
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Genetic engineering in biomimetic composites. Trends Biotechnol 2012; 30:191-7. [DOI: 10.1016/j.tibtech.2012.01.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 01/02/2012] [Accepted: 01/03/2012] [Indexed: 11/22/2022]
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257
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Jana M, Bandyopadhyay S. Conformational flexibility of a protein-carbohydrate complex and the structure and ordering of surrounding water. Phys Chem Chem Phys 2012; 14:6628-38. [PMID: 22460826 DOI: 10.1039/c2cp24104h] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Protein-carbohydrate non-covalent interactions are important to understand various biological processes in living organisms. One of the important issues in protein-carbohydrate binding is how the protein identifies the target carbohydrate and recognizes its conformational features. Surrounding water molecules are expected to play a critical role not only in mediating the recognition process but also in maintaining the structure of the complex. We carried out atomistic molecular dynamics (MD) simulations of an aqueous solution of the protein-carbohydrate complex formed between the hyaluronan binding domain (HABD) of the murine Cd44 protein and the octasaccharide hyaluronan (HA(8)). The conformational flexibilities of the protein and the carbohydrate, and the microscopic structure and ordering of water molecules around them in the complexed form have been explored. It is revealed that the formation of the complex is associated with significant immobilization of the monosaccharide units of the carbohydrate moiety that are involved in binding. Further, reduction in water densities around the binding residues of the two molecules in the complex with respect to their free forms clearly demonstrated that the recognition between the protein and the carbohydrate is facilitated by removal of a fraction of water molecules from regions around the binding domains.
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Affiliation(s)
- Madhurima Jana
- Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur - 721302, India
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258
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Nakjang S, Ndeh DA, Wipat A, Bolam DN, Hirt RP. A novel extracellular metallopeptidase domain shared by animal host-associated mutualistic and pathogenic microbes. PLoS One 2012; 7:e30287. [PMID: 22299034 PMCID: PMC3267712 DOI: 10.1371/journal.pone.0030287] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 12/16/2011] [Indexed: 12/20/2022] Open
Abstract
The mucosal microbiota is recognised as an important factor for our health, with many disease states linked to imbalances in the normal community structure. Hence, there is considerable interest in identifying the molecular basis of human-microbe interactions. In this work we investigated the capacity of microbes to thrive on mucosal surfaces, either as mutualists, commensals or pathogens, using comparative genomics to identify co-occurring molecular traits. We identified a novel domain we named M60-like/PF13402 (new Pfam entry PF13402), which was detected mainly among proteins from animal host mucosa-associated prokaryotic and eukaryotic microbes ranging from mutualists to pathogens. Lateral gene transfers between distantly related microbes explained their shared M60-like/PF13402 domain. The novel domain is characterised by a zinc-metallopeptidase-like motif and is distantly related to known viral enhancin zinc-metallopeptidases. Signal peptides and/or cell surface anchoring features were detected in most microbial M60-like/PF13402 domain-containing proteins, indicating that these proteins target an extracellular substrate. A significant subset of these putative peptidases was further characterised by the presence of associated domains belonging to carbohydrate-binding module family 5/12, 32 and 51 and other glycan-binding domains, suggesting that these novel proteases are targeted to complex glycoproteins such as mucins. An in vitro mucinase assay demonstrated degradation of mammalian mucins by a recombinant form of an M60-like/PF13402-containing protein from the gut mutualist Bacteroides thetaiotaomicron. This study reveals that M60-like domains are peptidases targeting host glycoproteins. These peptidases likely play an important role in successful colonisation of both vertebrate mucosal surfaces and the invertebrate digestive tract by both mutualistic and pathogenic microbes. Moreover, 141 entries across various peptidase families described in the MEROPS database were also identified with carbohydrate-binding modules defining a new functional context for these glycan-binding domains and providing opportunities to engineer proteases targeting specific glycoproteins for both biomedical and industrial applications.
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Affiliation(s)
- Sirintra Nakjang
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Didier A. Ndeh
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Anil Wipat
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
- School of Computing Science, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David N. Bolam
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert P. Hirt
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
- * E-mail:
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259
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Agrawal P, Verma D, Daniell H. Expression of Trichoderma reesei β-mannanase in tobacco chloroplasts and its utilization in lignocellulosic woody biomass hydrolysis. PLoS One 2011; 6:e29302. [PMID: 22216240 PMCID: PMC3247253 DOI: 10.1371/journal.pone.0029302] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Accepted: 11/23/2011] [Indexed: 11/26/2022] Open
Abstract
Lignocellulosic ethanol offers a promising alternative to conventional fossil fuels. One among the major limitations in the lignocellulosic biomass hydrolysis is unavailability of efficient and environmentally biomass degrading technologies. Plant-based production of these enzymes on large scale offers a cost-effective solution. Cellulases, hemicellulases including mannanases and other accessory enzymes are required for conversion of lignocellulosic biomass into fermentable sugars. β-mannanase catalyzes endo-hydrolysis of the mannan backbone, a major constituent of woody biomass. In this study, the man1 gene encoding β-mannanase was isolated from Trichoderma reesei and expressed via the chloroplast genome. PCR and Southern hybridization analysis confirmed site-specific transgene integration into the tobacco chloroplast genomes and homoplasmy. Transplastomic plants were fertile and set viable seeds. Germination of seeds in the selection medium showed inheritance of transgenes into the progeny without any Mendelian segregation. Expression of endo-β-mannanase for the first time in plants facilitated its characterization for use in enhanced lignocellulosic biomass hydrolysis. Gel diffusion assay for endo-β-mannanase showed the zone of clearance confirming functionality of chloroplast-derived mannanase. Endo-β-mannanase expression levels reached up to 25 units per gram of leaf (fresh weight). Chloroplast-derived mannanase had higher temperature stability (40 °C to 70 °C) and wider pH optima (pH 3.0 to 7.0) than E.coli enzyme extracts. Plant crude extracts showed 6-7 fold higher enzyme activity than E.coli extracts due to the formation of disulfide bonds in chloroplasts, thereby facilitating their direct utilization in enzyme cocktails without any purification. Chloroplast-derived mannanase when added to the enzyme cocktail containing a combination of different plant-derived enzymes yielded 20% more glucose equivalents from pinewood than the cocktail without mannanase. Our results demonstrate that chloroplast-derived mannanase is an important component of enzymatic cocktail for woody biomass hydrolysis and should provide a cost-effective solution for its diverse applications in the biofuel, paper, oil, pharmaceutical, coffee and detergent industries.
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Affiliation(s)
- Pankaj Agrawal
- Department of Molecular Biology and Microbiology, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, United States of America
| | - Dheeraj Verma
- Department of Molecular Biology and Microbiology, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, United States of America
| | - Henry Daniell
- Department of Molecular Biology and Microbiology, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, United States of America
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260
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Zhao J, Shi P, Huang H, Li Z, Yuan T, Yang P, Luo H, Bai Y, Yao B. A novel thermoacidophilic and thermostable endo-β-1,4-glucanase from Phialophora sp. G5: its thermostability influenced by a distinct β-sheet and the carbohydrate-binding module. Appl Microbiol Biotechnol 2011; 95:947-55. [DOI: 10.1007/s00253-011-3807-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2011] [Revised: 10/29/2011] [Accepted: 12/01/2011] [Indexed: 10/14/2022]
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261
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A thermostable GH45 endoglucanase from yeast: impact of its atypical multimodularity on activity. Microb Cell Fact 2011; 10:103. [PMID: 22145993 PMCID: PMC3247070 DOI: 10.1186/1475-2859-10-103] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 12/06/2011] [Indexed: 11/21/2022] Open
Abstract
Background The gene encoding an atypical multi-modular glycoside hydrolase family 45 endoglucanase bearing five different family 1 carbohydrate binding modules (CBM1), designated PpCel45A, was identified in the Pichia pastoris GS115 genome. Results PpCel45A (full-length open reading frame), and three derived constructs comprising (i) the catalytic module with its proximal CBM1, (ii) the catalytic module only, and (iii) the five CBM1 modules without catalytic module, were successfully expressed to high yields (up to 2 grams per litre of culture) in P. pastoris X33. Although the constructs containing the catalytic module displayed similar activities towards a range of glucans, comparison of their biochemical characteristics revealed striking differences. We observed a high thermostability of PpCel45A (Half life time of 6 h at 80°C), which decreased with the removal of CBMs and glycosylated linkers. However, both binding to crystalline cellulose and hydrolysis of crystalline cellulose and cellohexaose were substantially boosted by the presence of one CBM rather than five. Conclusions The present study has revealed the specific features of the first characterized endo β-1,4 glucanase from yeast, whose thermostability is promising for biotechnological applications related to the saccharification of lignocellulosic biomass such as consolidated bioprocessing.
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262
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Xylan as by-product of biorefineries: Characteristics and potential use for food applications. Food Hydrocoll 2011. [DOI: 10.1016/j.foodhyd.2011.04.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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263
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Janeček Š, Svensson B, MacGregor EA. Structural and evolutionary aspects of two families of non-catalytic domains present in starch and glycogen binding proteins from microbes, plants and animals. Enzyme Microb Technol 2011; 49:429-40. [DOI: 10.1016/j.enzmictec.2011.07.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 07/04/2011] [Accepted: 07/06/2011] [Indexed: 10/18/2022]
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264
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Hydrophilic aromatic residue and in silico structure for carbohydrate binding module. PLoS One 2011; 6:e24814. [PMID: 21966371 PMCID: PMC3178555 DOI: 10.1371/journal.pone.0024814] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 08/18/2011] [Indexed: 01/13/2023] Open
Abstract
Carbohydrate binding modules (CBMs) are found in polysaccharide-targeting enzymes and increase catalytic efficiency. Because only a relatively small number of CBM structures have been solved, computational modeling represents an alternative approach in conjunction with experimental assessment of CBM functionality and ligand-binding properties. An accurate target-template sequence alignment is the crucial step during homology modeling. However, low sequence identities between target/template sequences can be a major bottleneck. We therefore incorporated the predicted hydrophilic aromatic residues (HARs) and secondary structure elements into our feature-incorporated alignment (FIA) algorithm to increase CBM alignment accuracy. An alignment performance comparison for FIA and six others was made, and the greatest average sequence identities and similarities were achieved by FIA. In addition, structure models were built for 817 representative CBMs. Our models possessed the smallest average surface-potential z scores. Besides, a large true positive value for liagnd-binding aromatic residue prediction was obtained by HAR identification. Finally, the pre-simulated CBM structures have been deposited in the Database of Simulated CBM structures (DS-CBMs). The web service is publicly available at http://dscbm.life.nthu.edu.tw/ and http://dscbm.cs.ntou.edu.tw/.
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265
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Mellegård H, Kovács ÁT, Lindbäck T, Christensen BE, Kuipers OP, Granum PE. Transcriptional responses of Bacillus cereus towards challenges with the polysaccharide chitosan. PLoS One 2011; 6:e24304. [PMID: 21931677 PMCID: PMC3169574 DOI: 10.1371/journal.pone.0024304] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 08/04/2011] [Indexed: 01/18/2023] Open
Abstract
The antibacterial activity of the polysaccharide chitosan towards different bacterial species has been extensively documented. The response mechanisms of bacteria exposed to this biopolymer and the exact molecular mechanism of action, however, have hardly been investigated. This paper reports the transcriptome profiling using DNA microarrays of the type-strain of Bacillus cereus (ATCC 14579) exposed to subinhibitory concentrations of two water-soluble chitosan preparations with defined chemical characteristics (molecular weight and degree of acetylation (F(A))). The expression of 104 genes was significantly altered upon chitosan A (weight average molecular weight (M(w)) 36.0 kDa, F(A) = 0.01) exposure and 55 genes when treated with chitosan B (M(w) 28.4 kDa, F(A) = 0.16). Several of these genes are involved in ion transport, especially potassium influx (BC0753-BC0756). Upregulation of a potassium transporting system coincides with previous studies showing a permeabilizing effect on bacterial cells of this polymer with subsequent loss of potassium. Quantitative PCR confirmed the upregulation of the BC0753 gene encoding the K(+)-transporting ATPase subunit A. A markerless gene replacement method was used to construct a mutant strain deficient of genes encoding an ATP-driven K(+) transport system (Kdp) and the KdpD sensor protein. Growth of this mutant strain in potassium limiting conditions and under salt stress did not affect the growth pattern or growth yield compared to the wild-type strain. The necessity of the Kdp system for potassium acquisition in B. cereus is therefore questionable. Genes involved in the metabolism of arginine, proline and other cellular constituents, in addition to genes involved in the gluconeogenesis, were also significantly affected. BC2798 encoding a chitin binding protein was significantly downregulated due to chitosan exposure. This study provides insight into the response mechanisms of B. cereus to chitosan treatment and the significance of the Kdp system in potassium influx under challenging conditions.
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Affiliation(s)
- Hilde Mellegård
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
| | - Ákos T. Kovács
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Toril Lindbäck
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
| | - Bjørn E. Christensen
- NOBIPOL, Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Oscar P. Kuipers
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Per E. Granum
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
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266
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CBM3d, a novel subfamily of family 3 carbohydrate-binding modules identified in Cel48A exoglucanase of Cellulosilyticum ruminicola. J Bacteriol 2011; 193:5199-206. [PMID: 21803997 DOI: 10.1128/jb.05227-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previously, we found that exoglucanase Cel48A from Cellulosilyticum ruminicola H1 bound intensively to Avicel; however, no known carbohydrate-binding module (CBM) was observed in the protein. Bioinformatics suggested that a C-terminal fragment of 127 amino acids, named the Cellulosilyticum-specific paralogous module (CPM), could function in binding. CPM-appended proteins are all putative (hemi)cellulases from Cellulosilyticum spp. In the present work, we demonstrated that Cel48A without the CPM retained only exoglucanase activity and lost the Avicel-binding ability, while the isolated CPM exhibited a high affinity for Avicel. In addition, the CPM bound to chitin, but not to soluble polysaccharides, making it a type A CBM, which binds only insoluble polysaccharides. Phylogenetic analysis clustered the CPM and its homologs as a separate branch that was distantly related to CBM subfamilies 3a (28% identity), 3b (24% identity), and 3c (21% identity). Sequence alignment revealed distinct secondary structures of the new CBM 3 group, in particular, a conserved Pro66-Trp67 insert preceding strand β4', a deletion preceding strand β6, and incomplete strands β8 and β9. An alanine scan for six aromatic and three nonaromatic amino acid residues (D66, P66, and R111) by site-directed mutagenesis determined that Phe62, Pro66, Trp67, Tyr68, Arg111, and Trp117 were the functional residues for binding. Among them, Phe62, Pro66, and Trp67 were the newly determined key sites in the CPM for binding. Three-dimensional homolog modeling revealed two types of substrate-binding sites, planar and groove, in the CPM. Thus, a new subfamily, CBM family 3d, is proposed.
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267
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Fungal enzyme sets for plant polysaccharide degradation. Appl Microbiol Biotechnol 2011; 91:1477-92. [PMID: 21785931 PMCID: PMC3160556 DOI: 10.1007/s00253-011-3473-2] [Citation(s) in RCA: 355] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 06/27/2011] [Accepted: 07/10/2011] [Indexed: 02/01/2023]
Abstract
Enzymatic degradation of plant polysaccharides has many industrial applications, such as within the paper, food, and feed industry and for sustainable production of fuels and chemicals. Cellulose, hemicelluloses, and pectins are the main components of plant cell wall polysaccharides. These polysaccharides are often tightly packed, contain many different sugar residues, and are branched with a diversity of structures. To enable efficient degradation of these polysaccharides, fungi produce an extensive set of carbohydrate-active enzymes. The variety of the enzyme set differs between fungi and often corresponds to the requirements of its habitat. Carbohydrate-active enzymes can be organized in different families based on the amino acid sequence of the structurally related catalytic modules. Fungal enzymes involved in plant polysaccharide degradation are assigned to at least 35 glycoside hydrolase families, three carbohydrate esterase families and six polysaccharide lyase families. This mini-review will discuss the enzymes needed for complete degradation of plant polysaccharides and will give an overview of the latest developments concerning fungal carbohydrate-active enzymes and their corresponding families.
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268
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Quantitative investigation of non-hydrolytic disruptive activity on crystalline cellulose and application to recombinant swollenin. Appl Microbiol Biotechnol 2011; 91:1353-63. [DOI: 10.1007/s00253-011-3421-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 05/16/2011] [Accepted: 05/17/2011] [Indexed: 11/26/2022]
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269
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Sarian FD, van der Kaaij RM, Kralj S, Wijbenga DJ, Binnema DJ, van der Maarel MJEC, Dijkhuizen L. Enzymatic degradation of granular potato starch by Microbacterium aurum strain B8.A. Appl Microbiol Biotechnol 2011; 93:645-54. [PMID: 21732245 PMCID: PMC3257434 DOI: 10.1007/s00253-011-3436-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 06/07/2011] [Accepted: 06/07/2011] [Indexed: 12/05/2022]
Abstract
Microbacterium aurum strain B8.A was isolated from the sludge of a potato starch-processing factory on the basis of its ability to use granular starch as carbon- and energy source. Extracellular enzymes hydrolyzing granular starch were detected in the growth medium of M. aurum B8.A, while the type strain M. aurum DSMZ 8600 produced very little amylase activity, and hence was unable to degrade granular starch. The strain B8.A extracellular enzyme fraction degraded wheat, tapioca and potato starch at 37 °C, well below the gelatinization temperature of these starches. Starch granules of potato were hydrolyzed more slowly than of wheat and tapioca, probably due to structural differences and/or surface area effects. Partial hydrolysis of starch granules by extracellular enzymes of strain B8.A resulted in large holes of irregular sizes in case of wheat and tapioca and many smaller pores of relatively homogeneous size in case of potato. The strain B8.A extracellular amylolytic system produced mainly maltotriose and maltose from both granular and soluble starch substrates; also, larger maltooligosaccharides were formed after growth of strain B8.A in rich medium. Zymogram analysis confirmed that a different set of amylolytic enzymes was present depending on the growth conditions of M. aurum B8.A. Some of these enzymes could be partly purified by binding to starch granules.
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Affiliation(s)
- Fean D Sarian
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
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270
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Cuyvers S, Dornez E, Delcour JA, Courtin CM. Occurrence and functional significance of secondary carbohydrate binding sites in glycoside hydrolases. Crit Rev Biotechnol 2011; 32:93-107. [DOI: 10.3109/07388551.2011.561537] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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271
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Yang JI, Chen LC, Shih YY, Hsieh C, Chen CY, Chen WM, Chen CC. Cloning and characterization of β-agarase AgaYT from Flammeovirga yaeyamensis strain YT. J Biosci Bioeng 2011; 112:225-32. [PMID: 21715227 DOI: 10.1016/j.jbiosc.2011.05.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 05/29/2011] [Accepted: 05/31/2011] [Indexed: 11/29/2022]
Abstract
A bacterium with potent agar-degrading capability was isolated from the surface of a red algae, Gracilaria tenuistipitata. Based on phenotypic characteristics, 16S rDNA gene sequence and a phylogenetic analysis, this bacterium was identified and named as Flammeovirga yaeyamensis strain YT. PCR using homology-based degenerate primers was employed to clone any agarase gene belonging to GH16 family encoded in F. yaeyamensis strain YT. The resolved 1512 nucleotides revealed that the cloned gene, namely AgaYT, encodes a protein of 503 amino acids comprising a signal peptide, a glycosyl hydrolase catalytic module and a C-terminal domain with an unknown function. The recombinant protein r-AgaYT is an endo-type β-agarase hydrolyzing agarose to yield neoagarobiose and neoagarotetraose as the main hydrolytic products. The specific activity of r-AgaYT was determined about 178.6 U mg(-1) at 40°C and pH 8.0.
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Affiliation(s)
- Jing-Iong Yang
- Department of Seafood Science, National Kaohsiung Marine University, No. 142 Hai-chuan Rd., Nan-tzu, Kaohsiung, Taiwan
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272
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Díaz A, Martínez-Pons C, Fita I, Ferrer JC, Guinovart JJ. Processivity and subcellular localization of glycogen synthase depend on a non-catalytic high affinity glycogen-binding site. J Biol Chem 2011; 286:18505-14. [PMID: 21464127 DOI: 10.1074/jbc.m111.236109] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Glycogen synthase, a central enzyme in glucose metabolism, catalyzes the successive addition of α-1,4-linked glucose residues to the non-reducing end of a growing glycogen molecule. A non-catalytic glycogen-binding site, identified by x-ray crystallography on the surface of the glycogen synthase from the archaeon Pyrococcus abyssi, has been found to be functionally conserved in the eukaryotic enzymes. The disruption of this binding site in both the archaeal and the human muscle glycogen synthases has a large impact when glycogen is the acceptor substrate. Instead, the catalytic efficiency remains essentially unchanged when small oligosaccharides are used as substrates. Mutants of the human muscle enzyme with reduced affinity for glycogen also show an altered intracellular distribution and a marked decrease in their capacity to drive glycogen accumulation in vivo. The presence of a high affinity glycogen-binding site away from the active center explains not only the long-recognized strong binding of glycogen synthase to glycogen but also the processivity and the intracellular localization of the enzyme. These observations demonstrate that the glycogen-binding site is a critical regulatory element responsible for the in vivo catalytic efficiency of GS.
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Affiliation(s)
- Adelaida Díaz
- Institute for Research in Biomedicine, Universitat de Barcelona, Barcelona, Spain
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273
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Glaring MA, Baumann MJ, Abou Hachem M, Nakai H, Nakai N, Santelia D, Sigurskjold BW, Zeeman SC, Blennow A, Svensson B. Starch-binding domains in the CBM45 family--low-affinity domains from glucan, water dikinase and α-amylase involved in plastidial starch metabolism. FEBS J 2011; 278:1175-85. [PMID: 21294843 DOI: 10.1111/j.1742-4658.2011.08043.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Starch-binding domains are noncatalytic carbohydrate-binding modules that mediate binding to granular starch. The starch-binding domains from the carbohydrate-binding module family 45 (CBM45, http://www.cazy.org) are found as N-terminal tandem repeats in a small number of enzymes, primarily from photosynthesizing organisms. Isolated domains from representatives of each of the two classes of enzyme carrying CBM45-type domains, the Solanum tuberosumα-glucan, water dikinase and the Arabidopsis thaliana plastidial α-amylase 3, were expressed as recombinant proteins and characterized. Differential scanning calorimetry was used to verify the conformational integrity of an isolated CBM45 domain, revealing a surprisingly high thermal stability (T(m) of 84.8 °C). The functionality of CBM45 was demonstrated in planta by yellow/green fluorescent protein fusions and transient expression in tobacco leaves. Affinities for starch and soluble cyclodextrin starch mimics were measured by adsorption assays, surface plasmon resonance and isothermal titration calorimetry analyses. The data indicate that CBM45 binds with an affinity of about two orders of magnitude lower than the classical starch-binding domains from extracellular microbial amylolytic enzymes. This suggests that low-affinity starch-binding domains are a recurring feature in plastidial starch metabolism, and supports the hypothesis that reversible binding, effectuated through low-affinity interaction with starch granules, facilitates dynamic regulation of enzyme activities and, hence, of starch metabolism.
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Affiliation(s)
- Mikkel A Glaring
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Kongens Lyngby, Denmark
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274
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Valdez HA, Peralta DA, Wayllace NZ, Grisolía MJ, Gomez-Casati DF, Busi MV. Preferential binding of SBD from Arabidopsis thaliana SSIII to polysaccharides: Study of amino acid residues involved. STARCH-STARKE 2011. [DOI: 10.1002/star.201000111] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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275
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Abstract
Carbohydrate-active enzymes face huge substrate diversity in a highly selective manner using only a limited number of available folds. They are therefore subjected to multiple divergent and convergent evolutionary events. This and their frequent modularity render their functional annotation in genomes difficult in a number of cases. In the present paper, a classification of polysaccharide lyases (the enzymes that cleave polysaccharides using an elimination instead of a hydrolytic mechanism) is shown thoroughly for the first time. Based on the analysis of a large panel of experimentally characterized polysaccharide lyases, we examined the correlation of various enzyme properties with the three levels of the classification: fold, family and subfamily. The resulting hierarchical classification, which should help annotate relevant genes in genomic efforts, is available and constantly updated at the Carbohydrate-Active Enzymes Database (http://www.cazy.org).
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276
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Marcus SE, Blake AW, Benians TAS, Lee KJD, Poyser C, Donaldson L, Leroux O, Rogowski A, Petersen HL, Boraston A, Gilbert HJ, Willats WGT, Knox JP. Restricted access of proteins to mannan polysaccharides in intact plant cell walls. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:191-203. [PMID: 20659281 DOI: 10.1111/j.1365-313x.2010.04319.x] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
How the diverse polysaccharides present in plant cell walls are assembled and interlinked into functional composites is not known in detail. Here, using two novel monoclonal antibodies and a carbohydrate-binding module directed against the mannan group of hemicellulose cell wall polysaccharides, we show that molecular recognition of mannan polysaccharides present in intact cell walls is severely restricted. In secondary cell walls, mannan esterification can prevent probe recognition of epitopes/ligands, and detection of mannans in primary cell walls can be effectively blocked by the presence of pectic homogalacturonan. Masking by pectic homogalacturonan is shown to be a widespread phenomenon in parenchyma systems, and masked mannan was found to be a feature of cell wall regions at pit fields. Direct fluorescence imaging using a mannan-specific carbohydrate-binding module and sequential enzyme treatments with an endo-β-mannanase confirmed the presence of cryptic epitopes and that the masking of primary cell wall mannan by pectin is a potential mechanism for controlling cell wall micro-environments.
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Affiliation(s)
- Susan E Marcus
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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277
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Bahari L, Gilad Y, Borovok I, Kahel-Raifer H, Dassa B, Nataf Y, Shoham Y, Lamed R, Bayer EA. Glycoside hydrolases as components of putative carbohydrate biosensor proteins in Clostridium thermocellum. J Ind Microbiol Biotechnol 2010; 38:825-32. [DOI: 10.1007/s10295-010-0848-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 08/16/2010] [Indexed: 11/28/2022]
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278
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Hervé C, Rogowski A, Blake AW, Marcus SE, Gilbert HJ, Knox JP. Carbohydrate-binding modules promote the enzymatic deconstruction of intact plant cell walls by targeting and proximity effects. Proc Natl Acad Sci U S A 2010; 107:15293-8. [PMID: 20696902 PMCID: PMC2930570 DOI: 10.1073/pnas.1005732107] [Citation(s) in RCA: 196] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cell wall degrading enzymes have a complex molecular architecture consisting of catalytic modules and noncatalytic carbohydrate-binding modules (CBMs). The function of CBMs in cell wall degrading processes is poorly understood. Here, we have evaluated the potential enzyme-targeting function of CBMs in the context of intact primary and secondary cell wall deconstruction. The capacity of a pectate lyase to degrade pectic homogalacturonan in primary cell walls was potentiated by cellulose-directed CBMs but not by xylan-directed CBMs. Conversely, the arabinofuranosidase-mediated removal of side chains from arabinoxylan in xylan-rich and cellulose-poor wheat grain endosperm cell walls was enhanced by a xylan-binding CBM but less so by a crystalline cellulose-specific module. The capacity of xylanases to degrade xylan in secondary cell walls was potentiated by both xylan- and cellulose-directed CBMs. These studies demonstrate that CBMs can potentiate the action of a cognate catalytic module toward polysaccharides in intact cell walls through the recognition of nonsubstrate polysaccharides. The targeting actions of CBMs therefore have strong proximity effects within cell wall structures, explaining why cellulose-directed CBMs are appended to many noncellulase cell wall hydrolases.
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Affiliation(s)
- Cécile Hervé
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Artur Rogowski
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HN, United Kingdom; and
| | - Anthony W. Blake
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Susan E. Marcus
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Harry J. Gilbert
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HN, United Kingdom; and
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602-4712
| | - J. Paul Knox
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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279
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Vincent F, Molin DD, Weiner RM, Bourne Y, Henrissat B. Structure of a polyisoprenoid binding domain from Saccharophagus degradans implicated in plant cell wall breakdown. FEBS Lett 2010; 584:1577-84. [PMID: 20227408 DOI: 10.1016/j.febslet.2010.03.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 03/09/2010] [Accepted: 03/09/2010] [Indexed: 12/01/2022]
Abstract
Saccharophagus degradans belongs to a recently discovered group of marine bacteria equipped with an arsenal of sugar cleaving enzymes coupled to carbohydrate-binding domains to degrade various insoluble complex polysaccharides. The modular Sde-1182 protein consists of a family 2 carbohydrate binding module linked to a X158 domain of unknown function. The 1.9 A and 1.55 A resolution crystal structures of the isolated X158 domain bound to the two related polyisoprenoid molecules, ubiquinone and octaprenyl pyrophosphate, unveil a beta-barrel architecture reminiscent of the YceI-like superfamily that resembles the architecture of the lipocalin fold. This unprecedented association coupling oxidoreduction and carbohydrate recognition events may have implications for effective nutrient uptake in the marine environment.
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Affiliation(s)
- Florence Vincent
- Architecture et Fonction des Macromolécules Biologiques, UMR6098, CNRS and Aix-Marseille Universities, Marseille, France.
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280
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Vincent F, Round A, Reynaud A, Bordi C, Filloux A, Bourne Y. Distinct oligomeric forms of the Pseudomonas aeruginosa RetS sensor domain modulate accessibility to the ligand binding site. Environ Microbiol 2009; 12:1775-86. [DOI: 10.1111/j.1462-2920.2010.02264.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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