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Bitter J, Pfeiffer M, Borg AJE, Kuhlmann K, Pavkov-Keller T, Sánchez-Murcia PA, Nidetzky B. Enzymatic β-elimination in natural product O- and C-glycoside deglycosylation. Nat Commun 2023; 14:7123. [PMID: 37932298 PMCID: PMC10628242 DOI: 10.1038/s41467-023-42750-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 10/20/2023] [Indexed: 11/08/2023] Open
Abstract
Biological degradation of natural product glycosides involves, alongside hydrolysis, β-elimination for glycosidic bond cleavage. Here, we discover an O-glycoside β-eliminase (OGE) from Agrobacterium tumefaciens that converts the C3-oxidized O-β-D-glucoside of phloretin (a plant-derived flavonoid) into the aglycone and the 2-hydroxy-3-keto-glycal elimination product. While unrelated in sequence, OGE is structurally homologous to, and shows effectively the same Mn2+ active site as, the C-glycoside deglycosylating enzyme (CGE) from a human intestinal bacterium implicated in β-elimination of 3-keto C-β-D-glucosides. We show that CGE catalyzes β-elimination of 3-keto O- and C-β-D-glucosides while OGE is specific for the O-glycoside substrate. Substrate comparisons and mutagenesis for CGE uncover positioning of aglycone for protonic assistance by the enzyme as critically important for C-glycoside cleavage. Collectively, our study suggests convergent evolution of active site for β-elimination of 3-keto O-β-D-glucosides. C-Glycoside cleavage is a specialized feature of this active site which is elicited by substrate through finely tuned enzyme-aglycone interactions.
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Affiliation(s)
- Johannes Bitter
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, A-8010, Graz, Austria
| | - Martin Pfeiffer
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, A-8010, Graz, Austria
| | - Annika J E Borg
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, A-8010, Graz, Austria
- Austrian Centre of Industrial Biotechnology, Krenngasse 37, A-8010, Graz, Austria
| | - Kirill Kuhlmann
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, Humboldtstraße 50/III, A-8010, Graz, Austria
| | - Tea Pavkov-Keller
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, Humboldtstraße 50/III, A-8010, Graz, Austria
- BioTechMed-Graz, Mozartgasse 12/II, A-8010, Graz, Austria
- BioHealth Field of Excellence, University of Graz, Humboldtstraße 50, A-8010, Graz, Austria
| | - Pedro A Sánchez-Murcia
- Laboratory of Computer-Aided Molecular Design, Division of Medicinal Chemistry, Otto-Loewi Research Center, Medical University of Graz, Neue Stiftingstalstraße 6/III, A-8010, Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, A-8010, Graz, Austria.
- Austrian Centre of Industrial Biotechnology, Krenngasse 37, A-8010, Graz, Austria.
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Goldmanns J, Röhling GA, Lipa MK, Scholand T, Deitert A, May T, Haas EP, Boy M, Herold A, Büchs J. Development of a chemically defined medium for Paenibacillus polymyxa by parallel online monitoring of the respiration activity in microtiter plates. BMC Biotechnol 2023; 23:25. [PMID: 37507713 PMCID: PMC10385886 DOI: 10.1186/s12896-023-00793-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND One critical parameter in microbial cultivations is the composition of the cultivation medium. Nowadays, the application of chemically defined media increases, due to a more defined and reproducible fermentation performance than in complex media. In order, to improve cost-effectiveness of fermentation processes using chemically defined media, the media should not contain nutrients in large excess. Additionally, to obtain high product yields, the nutrient concentrations should not be limiting. Therefore, efficient medium optimization techniques are required which adapt medium compositions to the specific nutrient requirements of microorganisms. RESULTS Since most Paenibacillus cultivation protocols so far described in literature are based on complex ingredients, in this study, a chemically defined medium for an industrially relevant Paenibacillus polymyxa strain was developed. A recently reported method, which combines a systematic experimental procedure in combination with online monitoring of the respiration activity, was applied and extended to identify growth limitations for Paenibacillus polymyxa. All cultivations were performed in microtiter plates. By systematically increasing the concentrations of different nutrient groups, nicotinic acid was identified as a growth-limiting component. Additionally, an insufficient buffer capacity was observed. After optimizing the growth in the chemically defined medium, the medium components were systematically reduced to contain only nutrients relevant for growth. Vitamins were reduced to nicotinic acid and biotin, and amino acids to methionine, histidine, proline, arginine, and glutamate. Nucleobases/-sides could be completely left out of the medium. Finally, the cultivation in the reduced medium was reproduced in a laboratory fermenter. CONCLUSION In this study, a reliable and time-efficient high-throughput methodology was extended to investigate limitations in chemically defined media. The interpretation of online measured respiration activities agreed well with the growth performance of samples measured in parallel via offline analyses. Furthermore, the cultivation in microtiter plates was validated in a laboratory fermenter. The results underline the benefits of online monitoring of the respiration activity already in the early stages of process development, to avoid limitations of medium components, oxygen limitation and pH inhibition during the scale-up.
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Affiliation(s)
- Jennifer Goldmanns
- RWTH Aachen University, AVT - Biochemical Engineering, Forckenbeckstraße 51, 52074, Aachen, Germany
| | - Georg Andreas Röhling
- RWTH Aachen University, AVT - Biochemical Engineering, Forckenbeckstraße 51, 52074, Aachen, Germany
| | - Marie Kristine Lipa
- RWTH Aachen University, AVT - Biochemical Engineering, Forckenbeckstraße 51, 52074, Aachen, Germany
| | - Theresa Scholand
- RWTH Aachen University, AVT - Biochemical Engineering, Forckenbeckstraße 51, 52074, Aachen, Germany
| | - Alexander Deitert
- RWTH Aachen University, AVT - Biochemical Engineering, Forckenbeckstraße 51, 52074, Aachen, Germany
| | - Tobias May
- BASF SE, Carl-Bosch-Straße 38, Ludwigshafen am Rhein, 67056, Germany
| | | | - Matthias Boy
- BASF SE, Carl-Bosch-Straße 38, Ludwigshafen am Rhein, 67056, Germany
| | - Andrea Herold
- BASF SE, Carl-Bosch-Straße 38, Ludwigshafen am Rhein, 67056, Germany
| | - Jochen Büchs
- RWTH Aachen University, AVT - Biochemical Engineering, Forckenbeckstraße 51, 52074, Aachen, Germany.
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Synbiotic Matchmaking in Lactobacillus plantarum: Substrate Screening and Gene-Trait Matching To Characterize Strain-Specific Carbohydrate Utilization. Appl Environ Microbiol 2020; 86:AEM.01081-20. [PMID: 32680865 DOI: 10.1128/aem.01081-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 07/13/2020] [Indexed: 12/20/2022] Open
Abstract
Synbiotics are food supplements that combine probiotics and prebiotics to synergistically elicit a health effect in humans. Lactobacillus plantarum exhibits remarkable genetic and phenotypic diversity, in particular in strain-specific carbohydrate utilization capacities, and several strains are marketed as probiotics. We have screened 77 L. plantarum strains for their abilities to utilize specific prebiotic fibers, revealing variable and strain-specific growth efficiencies on isomalto- and galactooligosaccharides. We identified a single strain within the screening panel that was able to effectively utilize inulin and fructooligosaccharides (FOS), which did not support efficient growth of the rest of the strains. In the panel we tested, we did not find strains that could utilize arabinoxylooligosaccharides or sulfated fucoidan. The strain-specific growth phenotype on isomaltooligosaccharides was further analyzed using high-performance anion-exchange chromatography, which revealed distinct substrate utilization phenotypes within the strain panel. The strain-specific phenotypes could be linked to the strains' genotypes by identifying gene clusters coding for carbohydrate membrane transport systems that are predicted to be involved in the utilization of isomaltose and other (unidentified) oligosaccharides in the isomaltooligosaccharide substrate.IMPORTANCE Synbiotics combine prebiotics and probiotics to synergistically enhance the health benefits associated with these ingredients. Lactobacillus plantarum is encountered as a natural inhabitant of the gastrointestinal tract, and specific strains are marketed as probiotics based on their strain-specific health-promoting activities. Strain-specific stimulation of growth through prebiotic substrates could enhance the persistence and/or activity of L. plantarum in situ Our study establishes a high-throughput screening model for prebiotic substrate utilization by individual strains of bacteria, which can be readily employed for synbiotic matchmaking approaches that aim to enhance the intestinal delivery of probiotics through strain-specific, selective growth stimulation.
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Liu H, Liu H, Yang S, Wang R, Wang T. Improved Expression and Optimization of Trehalose Synthase by Regulation of P glv in Bacillus subtilis. Sci Rep 2019; 9:6585. [PMID: 31036837 PMCID: PMC6488592 DOI: 10.1038/s41598-019-43172-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 04/08/2019] [Indexed: 01/08/2023] Open
Abstract
Trehalose synthase (TreS) converts maltose to trehalose, which has several important functions; therefore, enhancing TreS expression is desirable. Here, a recombinant Bacillus subtilis W800N (ΔamyE)-Pglv strain was constructed to achieve enhanced expression of TreS. Process optimization strategies were developed to improve the expression level of TreS in B. subtilis W800N (ΔamyE)-Pglv. Intracellular activity of TreS was induced using 60 g/L of maltose in shake flask culture. The protein activity reached 5211 ± 134 U/g at 33 °C and pH 7.0 in Luria-Bertani medium. A fed-batch fermentation strategy was applied in a 30 L fermenter containing 18 L terrific broth to achieve high cell density by replacing glycerol with high maltose syrup as a carbon source and an inducer. After 32 h of fermentation, recombinant B. subtilis W800N (ΔamyE)-Pglv activity reached 6850 ± 287 U/g dry cell weight. Our results demonstrate the efficiency of the Pglv promoter in increasing the expression of TreS in B. subtilis W800N (ΔamyE)-Pglv.
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Affiliation(s)
- Hongling Liu
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology(Shandong Academy of Sciences), Jinan, Shandong, 250353, China.,Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, QiLu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, 250353, China.,Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science &Technology), Ministry of Education, Tianjin, 300457, China
| | - Hao Liu
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science &Technology), Ministry of Education, Tianjin, 300457, China
| | - Shaojie Yang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology(Shandong Academy of Sciences), Jinan, Shandong, 250353, China.,Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, QiLu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, 250353, China
| | - Ruiming Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology(Shandong Academy of Sciences), Jinan, Shandong, 250353, China.,Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, QiLu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, 250353, China
| | - Tengfei Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology(Shandong Academy of Sciences), Jinan, Shandong, 250353, China. .,Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, QiLu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, 250353, China.
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Ramaniuk O, Převorovský M, Pospíšil J, Vítovská D, Kofroňová O, Benada O, Schwarz M, Šanderová H, Hnilicová J, Krásný L. σ I from Bacillus subtilis: Impact on Gene Expression and Characterization of σ I-Dependent Transcription That Requires New Types of Promoters with Extended -35 and -10 Elements. J Bacteriol 2018; 200:e00251-18. [PMID: 29914988 PMCID: PMC6088155 DOI: 10.1128/jb.00251-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/09/2018] [Indexed: 11/20/2022] Open
Abstract
The σI sigma factor from Bacillus subtilis is a σ factor associated with RNA polymerase (RNAP) that was previously implicated in adaptation of the cell to elevated temperature. Here, we provide a comprehensive characterization of this transcriptional regulator. By transcriptome sequencing (RNA-seq) of wild-type (wt) and σI-null strains at 37°C and 52°C, we identified ∼130 genes affected by the absence of σI Further analysis revealed that the majority of these genes were affected indirectly by σI The σI regulon, i.e., the genes directly regulated by σI, consists of 16 genes, of which eight (the dhb and yku operons) are involved in iron metabolism. The involvement of σI in iron metabolism was confirmed phenotypically. Next, we set up an in vitro transcription system and defined and experimentally validated the promoter sequence logo that, in addition to -35 and -10 regions, also contains extended -35 and -10 motifs. Thus, σI-dependent promoters are relatively information rich in comparison with most other promoters. In summary, this study supplies information about the least-explored σ factor from the industrially important model organism B. subtilisIMPORTANCE In bacteria, σ factors are essential for transcription initiation. Knowledge about their regulons (i.e., genes transcribed from promoters dependent on these σ factors) is the key for understanding how bacteria cope with the changing environment and could be instrumental for biotechnologically motivated rewiring of gene expression. Here, we characterize the σI regulon from the industrially important model Gram-positive bacterium Bacillus subtilis We reveal that σI affects expression of ∼130 genes, of which 16 are directly regulated by σI, including genes encoding proteins involved in iron homeostasis. Detailed analysis of promoter elements then identifies unique sequences important for σI-dependent transcription. This study thus provides a comprehensive view on this underexplored component of the B. subtilis transcription machinery.
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Affiliation(s)
- Olga Ramaniuk
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
- Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Martin Převorovský
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jiří Pospíšil
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Dragana Vítovská
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Olga Kofroňová
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Oldřich Benada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Marek Schwarz
- Laboratory of Bioinformatics, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Hana Šanderová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jarmila Hnilicová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Libor Krásný
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
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Enzymes Required for Maltodextrin Catabolism in Enterococcus faecalis Exhibit Novel Activities. Appl Environ Microbiol 2017; 83:AEM.00038-17. [PMID: 28455338 DOI: 10.1128/aem.00038-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 04/19/2017] [Indexed: 01/16/2023] Open
Abstract
Maltose and maltodextrins are formed during the degradation of starch or glycogen. Maltodextrins are composed of a mixture of maltooligosaccharides formed by α-1,4- but also some α-1,6-linked glucosyl residues. The α-1,6-linked glucosyl residues are derived from branching points in the polysaccharides. In Enterococcus faecalis, maltotriose is mainly transported and phosphorylated by a phosphoenolpyruvate:carbohydrate phosphotransferase system. The formed maltotriose-6″-phosphate is intracellularly dephosphorylated by a specific phosphatase, MapP. In contrast, maltotetraose and longer maltooligosaccharides up to maltoheptaose are taken up without phosphorylation via the ATP binding cassette transporter MdxEFG-MsmX. We show that the maltose-producing maltodextrin hydrolase MmdH (GenBank accession no. EFT41964) in strain JH2-2 catalyzes the first catabolic step of α-1,4-linked maltooligosaccharides. The purified enzyme converts even-numbered α-1,4-linked maltooligosaccharides (maltotetraose, etc.) into maltose and odd-numbered (maltotriose, etc.) into maltose and glucose. Inactivation of mmdH therefore prevents the growth of E. faecalis on maltooligosaccharides ranging from maltotriose to maltoheptaose. Surprisingly, MmdH also functions as a maltogenic α-1,6-glucosidase, because it converts the maltotriose isomer isopanose into maltose and glucose. In addition, E. faecalis contains a glucose-producing α-1,6-specific maltodextrin hydrolase (GenBank accession no. EFT41963, renamed GmdH). This enzyme converts panose, another maltotriose isomer, into glucose and maltose. A gmdH mutant had therefore lost the capacity to grow on panose. The genes mmdH and gmdH are organized in an operon together with GenBank accession no. EFT41962 (renamed mmgT). Purified MmgT transfers glucosyl residues from one α-1,4-linked maltooligosaccharide molecule to another. For example, it catalyzes the disproportionation of maltotriose by transferring a glucosyl residue to another maltotriose molecule, thereby forming maltotetraose and maltose together with a small amount of maltopentaose.IMPORTANCE The utilization of maltodextrins by Enterococcus faecalis has been shown to increase the virulence of this nosocomial pathogen. However, little is known about how this organism catabolizes maltodextrins. We identified two enzymes involved in the metabolism of various α-1,4- and α-1,6-linked maltooligosaccharides. We found that one of them functions as a maltose-producing α-glucosidase with relaxed linkage specificity (α-1,4 and α-1,6) and exo- and endoglucosidase activities. A third enzyme, which resembles amylomaltase, exclusively transfers glucosyl residues from one maltooligosaccharide molecule to another. Similar enzymes are present in numerous other Firmicutes, such as streptococci and lactobacilli, suggesting that these organisms follow the same maltose degradation pathway as E. faecalis.
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Engineering of Escherichia coli to facilitate efficient utilization of isomaltose and panose in industrial glucose feedstock. Appl Microbiol Biotechnol 2016; 101:2057-2066. [PMID: 27933453 PMCID: PMC5309279 DOI: 10.1007/s00253-016-8037-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/27/2016] [Accepted: 11/26/2016] [Indexed: 10/25/2022]
Abstract
Industrial glucose feedstock prepared by enzymatic digestion of starch typically contains significant amounts of disaccharides such as maltose and isomaltose and trisaccharides such as maltotriose and panose. Maltose and maltosaccharides can be utilized in Escherichia coli fermentation using industrial glucose feedstock because there is an intrinsic assimilation pathway for these sugars. However, saccharides that contain α-1,6 bonds, such as isomaltose and panose, are still present after fermentation because there is no metabolic pathway for these sugars. To facilitate more efficient utilization of glucose feedstock, we introduced glvA, which encodes phospho-α-glucosidase, and glvC, which encodes a subunit of the phosphoenolpyruvate-dependent maltose phosphotransferase system (PTS) of Bacillus subtilis, into E. coli. The heterologous expression of glvA and glvC conferred upon the recombinant the ability to assimilate isomaltose and panose. The recombinant E. coli assimilated not only other disaccharides but also trisaccharides, including alcohol forms of these saccharides, such as isomaltitol. To the best of our knowledge, this is the first report to show the involvement of the microbial PTS in the assimilation of trisaccharides. Furthermore, we demonstrated that an L-lysine-producing E. coli harboring glvA and glvC converted isomaltose and panose to L-lysine efficiently. These findings are expected to be beneficial for industrial fermentation.
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Viens P, Dubeau MP, Kimura A, Desaki Y, Shinya T, Shibuya N, Saito A, Brzezinski R. Uptake of chitosan-derived D-glucosamine oligosaccharides in Streptomyces coelicolor A3(2). FEMS Microbiol Lett 2015; 362:fnv048. [DOI: 10.1093/femsle/fnv048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/24/2015] [Indexed: 12/23/2022] Open
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Xu H, Qin Y, Huang Z, Liu Z. Characterization and site-directed mutagenesis of an α-galactosidase from the deep-sea bacterium Bacillus megaterium. Enzyme Microb Technol 2014; 56:46-52. [PMID: 24564902 DOI: 10.1016/j.enzmictec.2014.01.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 01/04/2014] [Accepted: 01/07/2014] [Indexed: 11/25/2022]
Abstract
A novel gene (BmelA) (1323bp) encoding an α-galactosidase of 440 amino acids was cloned from the deep-sea bacterium Bacillus megaterium and the protein was expressed in Escherichia coli BL21 (DE3) with an estimated molecular mass of about 45 kDa by SDS-PAGE. The enzyme belongs to glycoside hydrolase family 4, with the highest identity (74%) to α-galactosidase Mel4A from Bacillus halodurans among the characterized α-galactosidases. The recombinant BmelA displayed its maximum activity at 35 °C and pH 8.5-9.0 in 50 mM Tris-HCl buffer, and could hydrolyze different substrates with the Km values against p-nitrophenyl-α-D-galactopyranoside (pNP-α-Gal), raffinose and stachyose being 1.02±0.02, 2.24±0.11 and 3.42±0.17 mM, respectively. Besides, 4 mutants (I38 V, I38A, I38F and Q84A) were obtained by site-directed mutagenesis based on molecular modeling and sequence alignment. The kinetic analysis indicated that mutants I38 V and I38A exhibited a 1.7- and 1.4-fold increase over the wild type enzyme in catalytic efficiency (k(cat)/K(m)) against pNP-α-Gal, respectively, while mutant I38F showed a 3.5-fold decrease against pNP-α-Gal and mutant Q84A almost completely lost its activity. All the results suggest that I38 and Q84 sites play a vital role in enzyme activity probably due to their steric and polar effects on the predicted "tunnel" structure and NAD+ binding to the enzyme.
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Affiliation(s)
- Haibo Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yongjun Qin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Zongqing Huang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Ziduo Liu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
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Raatschen N, Wenzel M, Ole Leichert LI, Düchting P, Krämer U, Bandow JE. Extracting iron and manganese from bacteria with ionophores - a mechanism against competitors characterized by increased potency in environments low in micronutrients. Proteomics 2013; 13:1358-70. [PMID: 23412951 DOI: 10.1002/pmic.201200556] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 01/24/2013] [Accepted: 01/31/2013] [Indexed: 11/10/2022]
Abstract
To maintain their metal ion homeostasis, bacteria critically depend on membrane integrity and controlled ion translocation. Terrestrial Streptomyces species undermine the function of the cytoplasmic membrane as diffusion barrier for metal cations in competitors using ionophores. Although the properties of the divalent cation ionophores calcimycin and ionomycin have been characterized to some extent in vitro, their effects on bacterial ion homeostasis, the factors leading to bacterial cell death, and their ecological role are poorly understood. To gain insight into their antibacterial mechanism, we determined the metal ion composition of the soil bacterium Bacillus subtilis after treatment with calcimycin and ionomycin. Within 15 min the cells lost approximately half of their cellular iron and manganese content whereas calcium levels increased. The proteomic response of B. subtilis provided evidence that disturbance of metal cation homeostasis is accompanied by intracellular oxidative stress, which was confirmed with a ROS-specific fluorescent probe. B. subtilis showed enhanced sensitivity to the ionophores in medium lacking iron or manganese. Furthermore, in the presence of ionophores bacteria were sensitive to high calcium levels. These findings suggest that divalent cation ionophores are particularly effective against competing microorganisms in soils rich in available calcium and low in available iron and manganese.
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Affiliation(s)
- Nadja Raatschen
- Biology of Microorganisms, Ruhr University Bochum, Bochum, Germany
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Yu WL, Jiang YL, Pikis A, Cheng W, Bai XH, Ren YM, Thompson J, Zhou CZ, Chen Y. Structural insights into the substrate specificity of a 6-phospho-β-glucosidase BglA-2 from Streptococcus pneumoniae TIGR4. J Biol Chem 2013; 288:14949-58. [PMID: 23580646 DOI: 10.1074/jbc.m113.454751] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 6-phospho-β-glucosidase BglA-2 (EC 3.2.1.86) from glycoside hydrolase family 1 (GH-1) catalyzes the hydrolysis of β-1,4-linked cellobiose 6-phosphate (cellobiose-6'P) to yield glucose and glucose 6-phosphate. Both reaction products are further metabolized by the energy-generating glycolytic pathway. Here, we present the first crystal structures of the apo and complex forms of BglA-2 with thiocellobiose-6'P (a non-metabolizable analog of cellobiose-6'P) at 2.0 and 2.4 Å resolution, respectively. Similar to other GH-1 enzymes, the overall structure of BglA-2 from Streptococcus pneumoniae adopts a typical (β/α)8 TIM-barrel, with the active site located at the center of the convex surface of the β-barrel. Structural analyses, in combination with enzymatic data obtained from site-directed mutant proteins, suggest that three aromatic residues, Tyr(126), Tyr(303), and Trp(338), at subsite +1 of BglA-2 determine substrate specificity with respect to 1,4-linked 6-phospho-β-glucosides. Moreover, three additional residues, Ser(424), Lys(430), and Tyr(432) of BglA-2, were found to play important roles in the hydrolytic selectivity toward phosphorylated rather than non-phosphorylated compounds. Comparative structural analysis suggests that a tryptophan versus a methionine/alanine residue at subsite -1 may contribute to the catalytic and substrate selectivity with respect to structurally similar 6-phospho-β-galactosidases and 6-phospho-β-glucosidases assigned to the GH-1 family.
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Affiliation(s)
- Wei-Li Yu
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China
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Mokhtari A, Blancato VS, Repizo GD, Henry C, Pikis A, Bourand A, de Fátima Álvarez M, Immel S, Mechakra-Maza A, Hartke A, Thompson J, Magni C, Deutscher J. Enterococcus faecalis utilizes maltose by connecting two incompatible metabolic routes via a novel maltose 6'-phosphate phosphatase (MapP). Mol Microbiol 2013; 88:234-53. [PMID: 23490043 DOI: 10.1111/mmi.12183] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2013] [Indexed: 11/30/2022]
Abstract
Similar to Bacillus subtilis, Enterococcus faecalis transports and phosphorylates maltose via a phosphoenolpyruvate (PEP):maltose phosphotransferase system (PTS). The maltose-specific PTS permease is encoded by the malT gene. However, E. faecalis lacks a malA gene encoding a 6-phospho-α-glucosidase, which in B. subtilis hydrolyses maltose 6'-P into glucose and glucose 6-P. Instead, an operon encoding a maltose phosphorylase (MalP), a phosphoglucomutase and a mutarotase starts upstream from malT. MalP was suggested to split maltose 6-P into glucose 1-P and glucose 6-P. However, purified MalP phosphorolyses maltose but not maltose 6'-P. We discovered that the gene downstream from malT encodes a novel enzyme (MapP) that dephosphorylates maltose 6'-P formed by the PTS. The resulting intracellular maltose is cleaved by MalP into glucose and glucose 1-P. Slow uptake of maltose probably via a maltodextrin ABC transporter allows poor growth for the mapP but not the malP mutant. Synthesis of MapP in a B. subtilis mutant accumulating maltose 6'-P restored growth on maltose. MapP catalyses the dephosphorylation of intracellular maltose 6'-P, and the resulting maltose is converted by the B. subtilis maltose phosphorylase into glucose and glucose 1-P. MapP therefore connects PTS-mediated maltose uptake to maltose phosphorylase-catalysed metabolism. Dephosphorylation assays with a wide variety of phospho-substrates revealed that MapP preferably dephosphorylates disaccharides containing an O-α-glycosyl linkage.
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Affiliation(s)
- Abdelhamid Mokhtari
- INRA, Microbiologie de l'alimentation au service de la santé humaine (MICALIS), UMR1319, F-78350, Jouy en Josas, France
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13
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α-Galacturonidase(s): a new class of Family 4 glycoside hydrolases with strict specificity and a unique CHEV active site motif. FEBS Lett 2013; 587:799-803. [PMID: 23416295 DOI: 10.1016/j.febslet.2013.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 01/18/2013] [Accepted: 02/01/2013] [Indexed: 11/20/2022]
Abstract
The catalytic activity of the Family 4 glycosidase LplD protein, whose active site motif is CHEV, is unknown despite its crystal structure having been determined in 2008. Here we identify that activity as being an α-galacturonidase whose natural substrate is probably α-1,4-di-galacturonate (GalUA2). Phylogenetic analysis shows that LplD belongs to a monophyletic clade of CHEV Family 4 enzymes, of which four other members are also shown to be galacturonidases. Family GH 4 enzymes catalyze the cleavage of the glycosidic bond, via a non-canonical redox-assisted mechanism that contrasts with Koshland's double-displacement mechanism.
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14
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Abstract
From a generated PES, one can determine the relative energies of species involved, the sequence in which they occur, and the activation barrier(s) associated with individual steps or the overall mechanism. Furthermore, they can provide more insights than a simple indication of a path of sequential mechanistic structures and their energetic relationships. The investigation into the activation of O2 by alpha-ketoglutarate-dependent dioxygenase (AlkB) clearly shows the opportunity for spin inversion, where one can see that the lowest energy product may be formed via several possible routes. In the investigation of uroporphyrinogen decarboxylase III (UROD), the use of QM/MM methods allowed for the inclusion of the anisotropic protein environment providing greater insight into the rate-limiting barrier. Lastly, the mechanism of 6-phospho-α-glucosidase (GlvA) was discussed using different active site models. In particular, a continuum model PES was compared to the gas-phase PES.
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Gänzle MG, Follador R. Metabolism of oligosaccharides and starch in lactobacilli: a review. Front Microbiol 2012; 3:340. [PMID: 23055996 PMCID: PMC3458588 DOI: 10.3389/fmicb.2012.00340] [Citation(s) in RCA: 238] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 09/04/2012] [Indexed: 01/02/2023] Open
Abstract
Oligosaccharides, compounds that are composed of 2-10 monosaccharide residues, are major carbohydrate sources in habitats populated by lactobacilli. Moreover, oligosaccharide metabolism is essential for ecological fitness of lactobacilli. Disaccharide metabolism by lactobacilli is well understood; however, few data on the metabolism of higher oligosaccharides are available. Research on the ecology of intestinal microbiota as well as the commercial application of prebiotics has shifted the interest from (digestible) disaccharides to (indigestible) higher oligosaccharides. This review provides an overview on oligosaccharide metabolism in lactobacilli. Emphasis is placed on maltodextrins, isomalto-oligosaccharides, fructo-oligosaccharides, galacto-oligosaccharides, and raffinose-family oligosaccharides. Starch is also considered. Metabolism is discussed on the basis of metabolic studies related to oligosaccharide metabolism, information on the cellular location and substrate specificity of carbohydrate transport systems, glycosyl hydrolases and phosphorylases, and the presence of metabolic genes in genomes of 38 strains of lactobacilli. Metabolic pathways for disaccharide metabolism often also enable the metabolism of tri- and tetrasaccharides. However, with the exception of amylase and levansucrase, metabolic enzymes for oligosaccharide conversion are intracellular and oligosaccharide metabolism is limited by transport. This general restriction to intracellular glycosyl hydrolases differentiates lactobacilli from other bacteria that adapted to intestinal habitats, particularly Bifidobacterium spp.
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Affiliation(s)
- Michael G. Gänzle
- Department of Agricultural, Food and Nutritional Science, University of AlbertaEdmonton, AB, Canada
| | - Rainer Follador
- Department of Agricultural, Food and Nutritional Science, University of AlbertaEdmonton, AB, Canada
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Bidossi A, Mulas L, Decorosi F, Colomba L, Ricci S, Pozzi G, Deutscher J, Viti C, Oggioni MR. A functional genomics approach to establish the complement of carbohydrate transporters in Streptococcus pneumoniae. PLoS One 2012; 7:e33320. [PMID: 22428019 PMCID: PMC3302838 DOI: 10.1371/journal.pone.0033320] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 02/10/2012] [Indexed: 01/02/2023] Open
Abstract
The aerotolerant anaerobe Streptococcus pneumoniae is part of the normal nasopharyngeal microbiota of humans and one of the most important invasive pathogens. A genomic survey allowed establishing the occurrence of twenty-one phosphotransferase systems, seven carbohydrate uptake ABC transporters, one sodium:solute symporter and a permease, underlining an exceptionally high capacity for uptake of carbohydrate substrates. Despite high genomic variability, combined phenotypic and genomic analysis of twenty sequenced strains did assign the substrate specificity only to two uptake systems. Systematic analysis of mutants for most carbohydrate transporters enabled us to assign a phenotype and substrate specificity to twenty-three transport systems. For five putative transporters for galactose, pentoses, ribonucleosides and sulphated glycans activity was inferred, but not experimentally confirmed and only one transport system remains with an unknown substrate and lack of any functional annotation. Using a metabolic approach, 80% of the thirty-two fermentable carbon substrates were assigned to the corresponding transporter. The complexity and robustness of sugar uptake is underlined by the finding that many transporters have multiple substrates, and many sugars are transported by more than one system. The present work permits to draw a functional map of the complete arsenal of carbohydrate utilisation proteins of pneumococci, allows re-annotation of genomic data and might serve as a reference for related species. These data provide tools for specific investigation of the roles of the different carbon substrates on pneumococcal physiology in the host during carriage and invasive infection.
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Affiliation(s)
- Alessandro Bidossi
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Laura Mulas
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Francesca Decorosi
- Sezione Microbiologia, Dip. Biotecnologie Agrarie, Università degli Studi di Firenze, Firenze, Italy
| | - Leonarda Colomba
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Susanna Ricci
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Gianni Pozzi
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
- UOC Batteriologia, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | - Carlo Viti
- Sezione Microbiologia, Dip. Biotecnologie Agrarie, Università degli Studi di Firenze, Firenze, Italy
| | - Marco Rinaldo Oggioni
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
- UOC Batteriologia, Azienda Ospedaliera Universitaria Senese, Siena, Italy
- * E-mail:
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Cobucci-Ponzano B, Moracci M. Glycosynthases as tools for the production of glycan analogs of natural products. Nat Prod Rep 2012; 29:697-709. [DOI: 10.1039/c2np20032e] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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18
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Thompson J, Pikis A. Metabolism of sugars by genetically diverse species of oral Leptotrichia. Mol Oral Microbiol 2011; 27:34-44. [PMID: 22230464 DOI: 10.1111/j.2041-1014.2011.00627.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Leptotrichia buccalis ATCC 14201 is a gram-negative, anaerobic rod-shaped bacterium resident in oral biofilm at the tooth surface. The sequenced genome of this organism reveals three contiguous genes at loci: Lebu_1525, Lebu_1526 and Lebu_1527. The translation products of these genes exhibit significant homology with phospho-α-glucosidase (Pagl), a regulatory protein (GntR) and a phosphoenol pyruvate-dependent sugar transport protein (EIICB), respectively. In non-oral bacterial species, these genes comprise the sim operon that facilitates sucrose isomer metabolism. Growth studies showed that L. buccalis fermented a wide variety of carbohydrates, including four of the five isomers of sucrose. Growth on the isomeric disaccharides elicited expression of a 50-kDa polypeptide comparable in size to that encoded by Lebu_1525. The latter gene was cloned, and the expressed protein was purified to homogeneity from Escherichia coli TOP10 cells. In the presence of two cofactors, NAD(+) and Mn(2+) ions, the enzyme readily hydrolyzed p-nitrophenyl-α-glucopyranoside 6-phosphate (pNPαG6P), a chromogenic analogue of the phosphorylated isomers of sucrose. By comparative sequence alignment, immunoreactivity and signature motifs, the enzyme can be assigned to the phospho-α-glucosidase (Pagl) clade of Family 4 of the glycosyl hydrolase super family. We suggest that the products of Lebu_1527 and Lebu_1525, catalyze the phosphorylative translocation and hydrolysis of sucrose isomers in L. buccalis, respectively. Four genetically diverse, but 16S rDNA-related, species of Leptotrichia have recently been described: L. goodfellowii, L. hofstadii, L. shahii and L. wadei. The phenotypic traits of these new species, with respect to carbohydrate utilization, have also been determined.
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Affiliation(s)
- J Thompson
- Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, NIDCR, National Institutes of Health, Bethesda, MD 20892, USA.
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19
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20
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Chakladar S, Cheng L, Choi M, Liu J, Bennet AJ. Mechanistic Evaluation of MelA α-Galactosidase from Citrobacter freundii: A Family 4 Glycosyl Hydrolase in Which Oxidation Is Rate-Limiting. Biochemistry 2011; 50:4298-308. [DOI: 10.1021/bi101808h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Saswati Chakladar
- Department of Chemistry and ‡Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Lydia Cheng
- Department of Chemistry and ‡Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Mary Choi
- Department of Chemistry and ‡Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - James Liu
- Department of Chemistry and ‡Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Andrew J. Bennet
- Department of Chemistry and ‡Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
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21
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Huang W, Llano J, Gauld JW. Redox mechanism of glycosidic bond hydrolysis catalyzed by 6-phospho-alpha-glucosidase: a DFT study. J Phys Chem B 2010; 114:11196-206. [PMID: 20698522 DOI: 10.1021/jp102399h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glycosidic bonds are remarkably resistant to cleavage by chemical hydrolysis. Glycoside hydrolases catalyze their selective hydrolysis in oligosaccharides, polysaccharides, and glycoconjugates by following nonredox catalytic pathways or a net redox-neutral catalytic pathway using NAD(+) and divalent metal ions as cofactors. GlvA (6-phospho-alpha-glucosidase) is a glycosidase belonging to family GH4 and follows a regioselective redox-neutral mechanism of glycosidic-bond hydrolysis that favors alpha- over beta-glycosides. Its proposed catalytic mechanism can be divided into two half-reactions: the first one activates the glucopyranose ring by successively forming intermediates that are oxidized at the 3-, 2-, and 1-positions of the ring, which ultimately facilitate the heterolytic deglycosylation. The second half-reaction is essentially the reverse of the first half-reaction, beginning with the pyranose ring hydroxylation at the anomeric carbon, and it is followed by 3-reduction and regeneration of the active forms of the catalytic site and its cofactors. We investigated the NAD(+)-dependent redox mechanism of glycosidic bond hydrolysis as catalyzed by GlvA through the combined application of density functional theory and a self-consistent reaction field to a large active-site model obtained from the crystallographic structure of the enzyme, then we applied natural bond orbital and second-order perturbation analyses to monitor the electron flow and change in oxidation state on each atomic center along the reaction coordinate to rationalize the energetics and regioselectivity of this catalytic mechanism. We find that in GlvA, the redox catalytic mechanism of hydrolysis is driven by the gradual strengthening of the axial endo-anomeric component within the hexose ring along the reaction coordinate to facilitate the heterolytic dissociation of the axial C1-O bond. In addition, the combined influence of specific components of the generalized anomeric effect fully explains the regioselectivity observed in the catalytic activity of GlvA.
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Affiliation(s)
- Wenjuan Huang
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
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22
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Ming YM, Wei ZW, Lin CY, Sheng GY. Development of a Bacillus subtilis expression system using the improved Pglv promoter. Microb Cell Fact 2010; 9:55. [PMID: 20618987 PMCID: PMC2908567 DOI: 10.1186/1475-2859-9-55] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 07/10/2010] [Indexed: 11/12/2022] Open
Abstract
Background B. subtilis is an important organism in the biotechnological application. The efficient expression system is desirable in production of recombinant gene products in B. subtilis. Recently, we developed a new inducible expression system in B. subtilis, which directed by B. subtilis maltose utilization operon promoter Pglv. The system demonstrated high-level expression for target proteins in B. subtilis when induced by maltose. However, the system was markedly repressed by glucose. This limited the application of the system as a high-expression tool in biotechnology field. The aim of this study was to further improve the Pglv promoter system and enhance its expression strength. Results Here, site-directed mutagenesis was facilitated to enhance the expression strength of Pglv. The transcription level from four mutants was increased. Production of β-Gal from the mutants reached the maximum 1.8 times as high as that of wildtype promoter. When induced by 5% maltose, the production of β-Gal from two mutants reached 14.3 U/ml and 13.8 U/ml, 63.5% and 57.5% higher than wildtype promoter (8.8 U/ml) respectively. Thus, site-directed mutagenesis alleviated the repression of glucose and improved the expression activity. To further improve the promoter system, the B. subtilis expression host was reconstructed, in which B. subtilis well-characterized constitutive promoter P43 replaced the promoter of the glv operon in B. subtilis chromosome through a double crossover event. The β-galactosidase production from the improved system (21.1 U/mL) increased compared to that from origin system. Meanwhile, the repression caused by glucose was further alleviated. Conclusions In this study, we obtained a mutated promoter Pglv-M1 through site-directed mutagenesis, which demonstrated high expression strength and alleviated the repression caused by glucose. Moreover, we alleviated the repression and enhanced the expression activity of the Pglv-M1 promoter system via reconstruction of the B. subtilis host. Thus, we provided a valuable expression system in B. subtilis.
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Affiliation(s)
- Yang M Ming
- College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China.
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23
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Nakai H, Baumann MJ, Petersen BO, Westphal Y, Schols H, Dilokpimol A, Hachem MA, Lahtinen SJ, Duus JØ, Svensson B. The maltodextrin transport system and metabolism in Lactobacillus acidophilus NCFM and production of novel α-glucosides through reverse phosphorolysis by maltose phosphorylase. FEBS J 2009; 276:7353-65. [DOI: 10.1111/j.1742-4658.2009.07445.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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24
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Hall BG, Pikis A, Thompson J. Evolution and biochemistry of family 4 glycosidases: implications for assigning enzyme function in sequence annotations. Mol Biol Evol 2009; 26:2487-97. [PMID: 19625389 DOI: 10.1093/molbev/msp162] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Glycosyl hydrolase Family 4 (GH4) is exceptional among the 114 families in this enzyme superfamily. Members of GH4 exhibit unusual cofactor requirements for activity, and an essential cysteine residue is present at the active site. Of greatest significance is the fact that members of GH4 employ a unique catalytic mechanism for cleavage of the glycosidic bond. By phylogenetic analysis, and from available substrate specificities, we have assigned a majority of the enzymes of GH4 to five subgroups. Our classification revealed an unexpected relationship between substrate specificity and the presence, in each subgroup, of a motif of four amino acids that includes the active-site Cys residue: alpha-glucosidase, CHE(I/V); alpha-galactosidase, CHSV; alpha-glucuronidase, CHGx; 6-phospho-alpha-glucosidase, CDMP; and 6-phospho-beta-glucosidase, CN(V/I)P. The question arises: Does the presence of a particular motif sufficiently predict the catalytic function of an unassigned GH4 protein? To test this hypothesis, we have purified and characterized the alpha-glucoside-specific GH4 enzyme (PalH) from the phytopathogen, Erwinia rhapontici. The CHEI motif in this protein has been changed by site-directed mutagenesis, and the effects upon substrate specificity have been determined. The change to CHSV caused the loss of all alpha-glucosidase activity, but the mutant protein exhibited none of the anticipated alpha-galactosidase activity. The Cys-containing motif may be suggestive of enzyme specificity, but phylogenetic placement is required for confidence in that specificity. The Acholeplasma laidlawii GH4 protein is phylogenetically a phospho-beta-glucosidase but has a unique SSSP motif. Lacking the initial Cys in that motif it cannot hydrolyze glycosides by the normal GH4 mechanism because the Cys is required to position the metal ion for hydrolysis, nor can it use the more common single or double-displacement mechanism of Koshland. Several considerations suggest that the protein has acquired a new function as the consequence of positive selection. This study emphasizes the importance of automatic annotation systems that by integrating phylogenetic analysis, functional motifs, and bioinformatics data, may lead to innovative experiments that further our understanding of biological systems.
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Affiliation(s)
- Barry G Hall
- Bellingham Research Institute, Bellingham, WA, USA.
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25
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Yip VLY, Withers SG. Family 4 glycoside hydrolases are special: The first β-elimination mechanism amongst glycoside hydrolases. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420500515926] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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26
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Seibold GM, Wurst M, Eikmanns BJ. Roles of maltodextrin and glycogen phosphorylases in maltose utilization and glycogen metabolism in Corynebacterium glutamicum. MICROBIOLOGY-SGM 2009; 155:347-358. [PMID: 19202084 DOI: 10.1099/mic.0.023614-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Corynebacterium glutamicum transiently accumulates large amounts of glycogen, when cultivated on glucose and other sugars as a source of carbon and energy. Apart from the debranching enzyme GlgX, which is required for the formation of maltodextrins from glycogen, alpha-glucan phosphorylases were assumed to be involved in glycogen degradation, forming alpha-glucose 1-phosphate from glycogen and from maltodextrins. We show here that C. glutamicum in fact possesses two alpha-glucan phosphorylases, which act as a glycogen phosphorylase (GlgP) and as a maltodextrin phosphorylase (MalP). By chromosomal inactivation and subsequent analysis of the mutant, cg1479 was identified as the malP gene. The deletion mutant C. glutamicum DeltamalP completely lacked MalP activity and showed reduced intracellular glycogen degradation, confirming the proposed pathway for glycogen degradation in C. glutamicum via GlgP, GlgX and MalP. Surprisingly, the DeltamalP mutant showed impaired growth, reduced viability and altered cell morphology on maltose and accumulated much higher concentrations of glycogen and maltodextrins than the wild-type during growth on this substrate, suggesting an additional role of MalP in maltose metabolism of C. glutamicum. Further assessment of enzyme activities revealed the presence of 4-alpha-glucanotransferase (MalQ), glucokinase (Glk) and alpha-phosphoglucomutase (alpha-Pgm), and the absence of maltose hydrolase, maltose phosphorylase and beta-Pgm, all three known to be involved in maltose utilization by Gram-positive bacteria. Based on these findings, we conclude that C. glutamicum metabolizes maltose via a pathway involving maltodextrin and glucose formation by MalQ, glucose phosphorylation by Glk and maltodextrin degradation via the reactions of MalP and alpha-Pgm, a pathway hitherto known to be present in Gram-negative rather than in Gram-positive bacteria.
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Affiliation(s)
- Gerd M Seibold
- Institute of Biochemistry, University of Cologne, D-50674 Cologne, Germany.,Institute of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany
| | - Martin Wurst
- Institute of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany
| | - Bernhard J Eikmanns
- Institute of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany
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Vocadlo DJ, Davies GJ. Mechanistic insights into glycosidase chemistry. Curr Opin Chem Biol 2009; 12:539-55. [PMID: 18558099 DOI: 10.1016/j.cbpa.2008.05.010] [Citation(s) in RCA: 300] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 05/19/2008] [Indexed: 11/16/2022]
Abstract
The enzymatic hydrolysis of the glycosidic bond continues to gain importance, reflecting the critically important roles complex glycans play in health and disease as well as the rekindled interest in enzymatic biomass conversion. Recent advances include the broadening of our understanding of enzyme reaction coordinates, through both computational and structural studies, improved understanding of enzyme inhibition through transition state mimicry and fascinating insights into mechanism yielded by physical organic chemistry approaches.
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Affiliation(s)
- David J Vocadlo
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Canada.
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28
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Transient oxidation as a mechanistic strategy in enzymatic catalysis. Curr Opin Chem Biol 2008; 12:532-8. [DOI: 10.1016/j.cbpa.2008.06.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Accepted: 06/17/2008] [Indexed: 11/18/2022]
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The sim operon facilitates the transport and metabolism of sucrose isomers in Lactobacillus casei ATCC 334. J Bacteriol 2008; 190:3362-73. [PMID: 18310337 DOI: 10.1128/jb.02008-07] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Inspection of the genome sequence of Lactobacillus casei ATCC 334 revealed two operons that might dissimilate the five isomers of sucrose. To test this hypothesis, cells of L. casei ATCC 334 were grown in a defined medium supplemented with various sugars, including each of the five isomeric disaccharides. Extracts prepared from cells grown on the sucrose isomers contained high levels of two polypeptides with M(r)s of approximately 50,000 and approximately 17,500. Neither protein was present in cells grown on glucose, maltose or sucrose. Proteomic, enzymatic, and Western blot analyses identified the approximately 50-kDa protein as an NAD(+)- and metal ion-dependent phospho-alpha-glucosidase. The oligomeric enzyme was purified, and a catalytic mechanism is proposed. The smaller polypeptide represented an EIIA component of the phosphoenolpyruvate-dependent sugar phosphotransferase system. Phospho-alpha-glucosidase and EIIA are encoded by genes at the LSEI_0369 (simA) and LSEI_0374 (simF) loci, respectively, in a block of seven genes comprising the sucrose isomer metabolism (sim) operon. Northern blot analyses provided evidence that three mRNA transcripts were up-regulated during logarithmic growth of L. casei ATCC 334 on sucrose isomers. Internal simA and simF gene probes hybridized to approximately 1.5- and approximately 1.3-kb transcripts, respectively. A 6.8-kb mRNA transcript was detected by both probes, which was indicative of cotranscription of the entire sim operon.
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Ming-Ming Y, Wei-Wei Z, Xi-Feng Z, Pei-Lin C. Construction and characterization of a novel maltose inducible expression vector in Bacillus subtilis. Biotechnol Lett 2006; 28:1713-8. [PMID: 17001500 DOI: 10.1007/s10529-006-9146-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Accepted: 06/23/2006] [Indexed: 10/24/2022]
Abstract
A maltose-inducible expression vector in Bacillus subtilis has been developed and characterized. The vector permitted beta-galactosidase expression at a high level (maximum activity, 8.16 U/ml) when induced and its expression was markedly repressed by glucose. Using this vector, we successfully expressed the other two genes, bioA and vgb. This thus provided a potential expression system for cloned genes in B. subtilis.
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Affiliation(s)
- Yang Ming-Ming
- Institute of Biochemical Engineering, College of Material Science and Chemical Engineering, Zhejiang University, Hangzhou 310027, P.R. China
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Schönert S, Seitz S, Krafft H, Feuerbaum EA, Andernach I, Witz G, Dahl MK. Maltose and maltodextrin utilization by Bacillus subtilis. J Bacteriol 2006; 188:3911-22. [PMID: 16707683 PMCID: PMC1482931 DOI: 10.1128/jb.00213-06] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus subtilis can utilize maltose and maltodextrins that are derived from polysaccharides, like starch or glycogen. In this work, we show that maltose is taken up by a member of the phosphoenolpyruvate-dependent phosphotransferase system and maltodextrins are taken up by a maltodextrin-specific ABC transporter. Uptake of maltose by the phosphoenolpyruvate-dependent phosphotransferase system is mediated by maltose-specific enzyme IICB (MalP; synonym, GlvC), with an apparent K(m) of 5 microM and a V(max) of 91 nmol . min(-1) . (10(10) CFU)(-1). The maltodextrin-specific ABC transporter is composed of the maltodextrin binding protein MdxE (formerly YvdG), with affinities in the low micromolar range for maltodextrins, and the membrane-spanning components MdxF and MdxG (formerly YvdH and YvdI, respectively), as well as the energizing ATPase MsmX. Maltotriose transport occurs with an apparent K(m) of 1.4 microM and a V(max) of 4.7 nmol . min(-1) . (10(10) CFU)(-1).
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Affiliation(s)
- Stefan Schönert
- Lehrstuhl für Mikrobiologie, Fachbereich Biologie der Universität Konstanz, Universitätsstrasse 10, M605, D-78457 Konstanz, Germany.
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Pikis A, Hess S, Arnold I, Erni B, Thompson J. Genetic requirements for growth of Escherichia coli K12 on methyl-alpha-D-glucopyranoside and the five alpha-D-glucosyl-D-fructose isomers of sucrose. J Biol Chem 2006; 281:17900-8. [PMID: 16636060 DOI: 10.1074/jbc.m601183200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Strains of Escherichia coli K12, including MG-1655, accumulate methyl-alpha-D-glucopyranoside via the phosphoenolpyruvate-dependent glucose:phosphotransferase system (IICB(Glc)/IIA(Glc)). High concentrations of intracellular methyl-alpha-D-glucopyranoside 6-phosphate are toxic, and cell growth is prevented. However, transformation of E. coli MG-1655 with a plasmid (pAP1) encoding the gene aglB from Klebsiella pneumoniae resulted in excellent growth of the transformant MG-1655 (pAP1) on the glucose analog. AglB is an unusual NAD+/Mn2+-dependent phospho-alpha-glucosidase that promotes growth of MG-1655 (pAP1) by catalyzing the in vivo hydrolysis of methyl-alpha-D-glucopyranoside 6-phosphate to yield glucose 6-phosphate and methanol. When transformed with plasmid pAP2 encoding the K. pneumoniae genes aglB and aglA (an alpha-glucoside-specific transporter AglA (IICB(Agl))), strain MG-1655 (pAP2) metabolized a variety of other alpha-linked glucosides, including maltitol, isomaltose, and the following five isomers of sucrose: trehalulose alpha(1-->1), turanose alpha(1-->3), maltulose alpha(1-->4), leucrose alpha(1-->5), and palatinose alpha(1-->6). Remarkably, MG-1655 (pAP2) failed to metabolize sucrose alpha(1-->2). The E. coli K12 strain ZSC112L (ptsG::cat manXYZ nagE glk lac) can neither grow on glucose nor transport methyl-alpha-D-glucopyranoside. However, when transformed with pTSGH11 (encoding ptsG) or pAP2, this organism provided membranes that contained either the PtsG or AglA transporters, respectively. In vitro complementation of transporter-specific membranes with purified general phosphotransferase components showed that although PtsG and AglA recognized glucose and methyl-alpha-D-glucopyranoside, only AglA accepted other alpha-D-glucosides as substrates. Complementation experiments also revealed that IIA(Glc) was required for functional activity of both PtsG and AglA transporters. We conclude that AglA, AglB, and IIA(Glc) are necessary and sufficient for growth of E. coli K12 on methyl-alpha-D-glucoside and related alpha-D-glucopyranosides.
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Affiliation(s)
- Andreas Pikis
- Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research/NIH, Bldg. 30, Convent Drive, Bethesda, MD 20892, USA
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Yip VLY, Withers SG. Breakdown of oligosaccharides by the process of elimination. Curr Opin Chem Biol 2006; 10:147-55. [PMID: 16495121 DOI: 10.1016/j.cbpa.2006.02.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Accepted: 02/09/2006] [Indexed: 12/22/2022]
Abstract
Several new mechanisms for enzyme-catalyzed breakdown of oligosaccharides have been uncovered in recent years. A common feature is the recruitment of elimination steps rather than direct displacements. Bond cleavage can proceed via E1 mechanisms with cationic transition states or E1(cb) mechanisms with anionic transition states, and can even involve NAD(+)-mediated redox steps. A common feature emerging from studies on disparate syn-eliminating enzymes is the use of a single catalytic residue, often tyrosine, as both general acid and base.
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Affiliation(s)
- Vivian L Y Yip
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
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Abstract
Escherichia coli and Salmonella enterica serovar Typhimurium exhibit a remarkable versatility in the usage of different sugars as the sole source of carbon and energy, reflecting their ability to make use of the digested meals of mammalia and of the ample offerings in the wild. Degradation of sugars starts with their energy-dependent uptake through the cytoplasmic membrane and is carried on further by specific enzymes in the cytoplasm, destined finally for degradation in central metabolic pathways. As variant as the different sugars are, the biochemical strategies to act on them are few. They include phosphorylation, keto-enol isomerization, oxido/reductions, and aldol cleavage. The catabolic repertoire for using carbohydrate sources is largely the same in E. coli and in serovar Typhimurium. Nonetheless, significant differences are found, even among the strains and substrains of each species. We have grouped the sugars to be discussed according to their first step in metabolism, which is their active transport, and follow their path to glycolysis, catalyzed by the sugar-specific enzymes. We will first discuss the phosphotransferase system (PTS) sugars, then the sugars transported by ATP-binding cassette (ABC) transporters, followed by those that are taken up via proton motive force (PMF)-dependent transporters. We have focused on the catabolism and pathway regulation of hexose and pentose monosaccharides as well as the corresponding sugar alcohols but have also included disaccharides and simple glycosides while excluding polysaccharide catabolism, except for maltodextrins.
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Affiliation(s)
- Christoph Mayer
- Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany
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Hekmat O, Kim YW, Williams SJ, He S, Withers SG. Active-site peptide "fingerprinting" of glycosidases in complex mixtures by mass spectrometry. Discovery of a novel retaining beta-1,4-glycanase in Cellulomonas fimi. J Biol Chem 2005; 280:35126-35. [PMID: 16085650 DOI: 10.1074/jbc.m508434200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
New proteomics methods are required for targeting and identification of subsets of a proteome in an activity-based fashion. Here, we report the first gel-free, mass spectrometry-based strategy for mechanism-based profiling of retaining beta-endoglycosidases in complex proteomes. Using a biotinylated, cleavable 2-deoxy-2-fluoroxylobioside inactivator, we have isolated and identified the active-site peptides of target retaining beta-1,4-glycanases in systems of increasing complexity: pure enzymes, artificial proteomes, and the secreted proteome of the aerobic mesophilic soil bacterium Cellulomonas fimi. The active-site peptide of a new C. fimi beta-1,4-glycanase was identified in this manner, and the peptide sequence, which includes the catalytic nucleophile, is highly conserved among glycosidase family 10 members. The glycanase gene (GenBank accession number DQ146941) was cloned using inverse PCR techniques, and the protein was found to comprise a catalytic domain that shares approximately 70% sequence identity with those of xylanases from Streptomyces sp. and a family 2b carbohydrate-binding module. The new glycanase hydrolyzes natural and artificial xylo-configured substrates more efficiently than their cello-configured counterparts. It has a pH dependence very similar to that of known C. fimi retaining glycanases.
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Affiliation(s)
- Omid Hekmat
- Protein Engineering Network of Centres of Excellence of Canada, Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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Maltose phosphorylase from a deep-sea Paenibacillus sp.: Enzymatic properties and nucleotide and amino-acid sequences. Enzyme Microb Technol 2005. [DOI: 10.1016/j.enzmictec.2005.02.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Rajan SS, Yang X, Collart F, Yip VLY, Withers SG, Varrot A, Thompson J, Davies GJ, Anderson WF. Novel catalytic mechanism of glycoside hydrolysis based on the structure of an NAD+/Mn2+ -dependent phospho-alpha-glucosidase from Bacillus subtilis. Structure 2005; 12:1619-29. [PMID: 15341727 DOI: 10.1016/j.str.2004.06.020] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Revised: 06/11/2004] [Accepted: 06/27/2004] [Indexed: 11/30/2022]
Abstract
GlvA, a 6-phospho-alpha-glucosidase from Bacillus subtilis, catalyzes the hydrolysis of maltose-6'-phosphate and belongs to glycoside hydrolase family GH4. GH4 enzymes are unique in their requirement for NAD(H) and a divalent metal for activity. We have determined the crystal structure of GlvA in complex with its ligands to 2.05 A resolution. Analyses of the active site architecture, in conjunction with mechanistic studies and precedent from the nucleotide diphosphate hexose dehydratases and other systems, suggest a novel mechanism of glycoside hydrolysis by GlvA that involves both the NAD(H) and the metal.
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Affiliation(s)
- Shyamala S Rajan
- Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Varrot A, Yip VLY, Li Y, Rajan SS, Yang X, Anderson WF, Thompson J, Withers SG, Davies GJ. NAD+ and metal-ion dependent hydrolysis by family 4 glycosidases: structural insight into specificity for phospho-beta-D-glucosides. J Mol Biol 2005; 346:423-35. [PMID: 15670594 DOI: 10.1016/j.jmb.2004.11.058] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Revised: 11/14/2004] [Accepted: 11/23/2004] [Indexed: 11/17/2022]
Abstract
The import of disaccharides by many bacteria is achieved through their simultaneous translocation and phosphorylation by the phosphoenolpyruvate-dependent phosphotransferase system (PEP-PTS). The imported phospho-disaccharides are, in some cases, subsequently hydrolyzed by members of the unusual glycoside hydrolase family GH4. The GH4 enzymes, occasionally found also in bacteria such as Thermotoga maritima that do not utilise a PEP-PTS system, require both NAD(+) and Mn(2+) for catalysis. A further curiosity of this family is that closely related enzymes may show specificity for either alpha-d- or beta-d-glycosides. Here, we present, for the first time, the three-dimensional structure (using single-wavelength anomalous dispersion methods, harnessing extensive non-crystallographic symmetry) of the 6-phospho-beta-glycosidase, BglT, from T.maritima in native and complexed (NAD(+) and Glc6P) forms. Comparison of the active-center structure with that of the 6-phospho-alpha-glucosidase GlvA from Bacillus subtilis reveals a striking degree of structural similarity that, in light of previous kinetic isotope effect data, allows the postulation of a common reaction mechanism for both alpha and beta-glycosidases. Given that the "chemistry" occurs primarily on the glycone sugar and features no nucleophilic attack on the intact disaccharide substrate, modulation of anomeric specificity for alpha and beta-linkages is accommodated through comparatively minor structural changes.
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Affiliation(s)
- Annabelle Varrot
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5YW, UK
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Thompson J, Hess S, Pikis A. Genes malh and pagl of Clostridium acetobutylicum ATCC 824 encode NAD+- and Mn2+-dependent phospho-alpha-glucosidase(s). J Biol Chem 2003; 279:1553-61. [PMID: 14570887 DOI: 10.1074/jbc.m310733200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The genome of Clostridium acetobutylicum 824 contains two genes encoding NAD+, Mn2+, and dithiothreitol-dependent phospho-alpha-glucosidases that can be assigned to family 4 of the glycosylhydrolase superfamily. The two genes, designated malh (maltose 6-phosphate hydrolase) and pagl (phospho-alpha-glucosidase), respectively, reside in separate operons that also encode proteins of the phosphoenolpyruvate-dependent:sugar phosphotransferase system. C. acetobutylicum grows on a variety of alpha-linked glucosides, including maltose, methyl-alpha-d-glucoside, and the five isomers of sucrose. In the presence of the requisite cofactors, extracts of these cells readily hydrolyzed the chromogenic substrate p-nitrophenyl-alpha-d-glucopyranoside 6-phosphate, but whether hydrolysis reflected expression of enzymes encoded by the malh or pagl genes was not discernible by spectrophotometric analysis or polyacrylamide gel electrophoresis. Resolution of this question required the cloning of the malh and pagl genes, and subsequent high expression, purification, and characterization of maltose-6'-phosphate hydrolase (MalH) and phospho-alpha-glucosidase (PagL), respectively. MalH and PagL exhibit 50% residue identity, and in solution are tetramers comprising similar sized ( approximately 50 kDa) subunits. The two proteins cross-react with polyclonal rabbit antibody against phospho-alpha-glucosidase from Fusobacterium mortiferum. Purified MalH and PagL cleaved p-nitrophenyl-alpha-d-glucopyranoside 6-phosphate with comparable efficiency, but only MalH catalyzed the hydrolysis of disaccharide 6'-phosphates formed via the phosphoenolpyruvate-dependent:sugar phosphotransferase system. Importantly, analysis of the proteome of C. acetobutylicum 824 by electrospray ionization-mass spectrometry confirmed expression of MalH during growth on many alpha-glucosides tested. Site-directed changes C169S and D170N yielded full-length, but catalytically inactive MalH. Of the two putative operons, our findings suggest that only proteins encoded by the mal operon participate in the dissimilation of maltose and related O-alpha-linked glucosides by C. acetobutylicum 824.
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Affiliation(s)
- John Thompson
- Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, NIDCR, NIH, Bethesda, MD 20892, USA.
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40
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Lodge JA, Maier T, Liebl W, Hoffmann V, Sträter N. Crystal structure of Thermotoga maritima alpha-glucosidase AglA defines a new clan of NAD+-dependent glycosidases. J Biol Chem 2003; 278:19151-8. [PMID: 12588867 DOI: 10.1074/jbc.m211626200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycoside hydrolase family 4 represents an unusual group of glucosidases with a requirement for NAD+, divalent metal cations, and reducing conditions. The family is also unique in its inclusion of both alpha- and beta-specific enzymes. The alpha-glucosidase A, AglA, from Thermotoga maritima is a typical glycoside hydrolase family 4 enzyme, requiring NAD+ and Mn2+ as well as strongly reducing conditions for activity. Here we present the crystal structure of the protein complexed with NAD+ and maltose, refined at a resolution of 1.9 A. The NAD+ is bound to a typical Rossman fold NAD+-binding site, and the nicotinamide moiety is localized close to the maltose substrate. Within the active site the conserved Cys-174 and surrounding histidines are positioned to play a role in the hydrolysis reaction. The electron density maps indicate that Cys-174 is oxidized to a sulfinic acid. Most likely, the strongly reducing conditions are necessary to reduce the oxidized cysteine side chain. Notably, the canonical set of catalytic acidic residues common to other glucosidases is not present in the active site. This, combined with a high structural homology to NAD-dependent dehydrogenases, suggests an unusual and possibly unique mechanism of action for a glycoside-hydrolyzing enzyme.
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Affiliation(s)
- Jacinta A Lodge
- Institut für Chemie, Takustrasse 6, Freie Universität Berlin, D-14195 Berlin
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Thompson J, Lichtenthaler FW, Peters S, Pikis A. Beta-glucoside kinase (BglK) from Klebsiella pneumoniae. Purification, properties, and preparative synthesis of 6-phospho-beta-D-glucosides. J Biol Chem 2002; 277:34310-21. [PMID: 12110692 DOI: 10.1074/jbc.m206397200] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ATP-dependent beta-glucoside kinase (BglK) has been purified from cellobiose-grown cells of Klebsiella pneumoniae. In solution, the enzyme (EC ) exists as a homotetramer composed of non-covalently linked subunits of M(r) approximately 33,000. Determination of the first 28 residues from the N terminus of the protein allowed the identification and cloning of bglK from genomic DNA of K. pneumoniae. The open reading frame (ORF) of bglK encodes a 297-residue polypeptide of calculated M(r) 32,697. A motif of 7 amino acids (AFD(7)IG(9)GT) near the N terminus may comprise the ATP-binding site, and residue changes D7G and G9A yielded catalytically inactive proteins. BglK was progressively inactivated (t(12) approximately 19 min) by N-ethylmaleimide, but ATP afforded considerable protection against the inhibitor. By the presence of a centrally located signature sequence, BglK can be assigned to the ROK (Repressor, ORF, Kinase) family of proteins. Preparation of (His6)BglK by nickel-nitrilotriacetic acid-agarose chromatography provided high purity enzyme in quantity sufficient for the preparative synthesis (200-500 mg) of ten 6-phospho-beta-d-glucosides, including cellobiose-6'-P, gentiobiose-6'-P, cellobiitol-6-P, salicin-6-P, and arbutin-6-P. These (and other) derivatives are substrates for phospho-beta-glucosidase(s) belonging to Families 1 and 4 of the glycosylhydrolase superfamily. The structures, physicochemical properties, and phosphorylation site(s) of the 6-phospho-beta-d-glucosides have been determined by fast atom bombardment-negative ion spectrometry, thin-layer chromatography, and (1)H and (13)C NMR spectroscopy. The recently sequenced genomes of two Listeria species, L. monocytogenes EGD-e and L. innocua CLIP 11262, contain homologous genes (lmo2764 and lin2907, respectively) that encode a 294-residue polypeptide (M(r) approximately 32,200) that exhibits approximately 58% amino acid identity with BglK. The protein encoded by the two genes exhibits beta-glucoside kinase activity and cross-reacts with polyclonal antibody to (His6)BglK from K. pneumoniae. The location of lmo2764 and lin2907 within a beta-glucoside (cellobiose):phosphotransferase system operon, may presage both enzymatic (kinase) and regulatory functions for the BglK homolog in Listeria species.
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Affiliation(s)
- John Thompson
- Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, NIDCR/National Institutes of Health, 30 Convent Drive, MSC-4350, Bethesda, MD 20892, USA.
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Thompson J. Purification and some properties of phospho-beta-galactosidase from the Gram-negative oral bacterium Leptotrichia buccalis ATCC 14201. FEMS Microbiol Lett 2002; 214:183-8. [PMID: 12351228 DOI: 10.1111/j.1574-6968.2002.tb11344.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Phospho-beta-galactosidase (P-beta-gal; EC 3.2.1.85) is induced during growth of Leptotrichia buccalis ATCC 14201 on lactose and lactulose. The enzyme has been purified to electrophoretic homogeneity (M(r) approximately 53 kDa, pI approximately 4.8), and kinetic parameters have been determined using the chromogenic analog o-nitrophenyl-beta-D-galactopyranoside-6-phosphate as substrate. Both ATP and galactose-6-phosphate are inhibitors of P-beta-gal activity. Microsequence analysis has identified the first 32 residues from the N-terminus of the protein, and by comparative sequence alignment the enzyme can be assigned to Family 1 of the glycosylhydrolase superfamily. Polyclonal antibody against the enzyme permits the highly specific immuno-detection of P-beta-gal in cell-free extracts of L. buccalis. Although described previously in several Gram-positive species, this is the first reported purification of P-beta-gal from a Gram-negative organism.
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Affiliation(s)
- John Thompson
- Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, NIDCR, National Institutes of Health, Bethesda, MD 20892, USA.
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Raasch C, Armbrecht M, Streit W, Höcker B, Sträter N, Liebl W. Identification of residues important for NAD+ binding by the Thermotoga maritima alpha-glucosidase AglA, a member of glycoside hydrolase family 4. FEBS Lett 2002; 517:267-71. [PMID: 12062450 DOI: 10.1016/s0014-5793(02)02641-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The NAD+-requiring enzymes of glycoside hydrolase family 4 (GHF4) contain a region with a conserved Gly-XXX-Gly-Ser (GXGS) motif near their N-termini that is reminiscent of the fingerprint region of the Rossmann fold, a conserved structural motif of classical nicotinamide nucleotide-binding proteins. The function of this putative NAD+-binding motif in the alpha-glucosidase AglA of Thermotoga maritima was probed by directed mutagenesis. The K(d) for NAD+ of the AglA mutants G10A, G12A and S13A was increased by about 300-, 5-, and 9-fold, respectively, while their K(m) for p-nitrophenyl-alpha-glucopyranoside was not seriously affected. The results indicate that the GXGS motif is indeed important for NAD+ binding by the glycosidases of GHF4.
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Affiliation(s)
- Carsten Raasch
- Institut für Mikrobiologie und Genetik, Georg-August-Universität, Göttingen, Germany
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Pikis A, Immel S, Robrish SA, Thompson J. Metabolism of sucrose and its five isomers by Fusobacterium mortiferum. MICROBIOLOGY (READING, ENGLAND) 2002; 148:843-852. [PMID: 11882720 DOI: 10.1099/00221287-148-3-843] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fusobacterium mortiferum utilizes sucrose [glucose-fructose in alpha(1-->2) linkage] and its five isomeric alpha-D-glucosyl-D-fructoses as energy sources for growth. Sucrose-grown cells are induced for both sucrose-6-phosphate hydrolase (S6PH) and fructokinase (FK), but the two enzymes are not expressed above constitutive levels during growth on the isomeric compounds. Extracts of cells grown previously on the sucrose isomers trehalulose alpha(1-->1), turanose alpha(1-->3), maltulose alpha(1-->4), leucrose alpha(1-->5) and palatinose alpha(1-->6) contained high levels of an NAD+ plus metal-dependent phospho-alpha-glucosidase (MalH). The latter enzyme was not induced during growth on sucrose. MalH catalysed the hydrolysis of the 6'-phosphorylated derivatives of the five isomers to yield glucose 6-phosphate and fructose, but sucrose 6-phosphate itself was not a substrate. Unexpectedly, MalH hydrolysed both alpha- and beta-linked stereomers of the chromogenic analogue p-nitrophenyl glucoside 6-phosphate. The gene malH is adjacent to malB and malR, which encode an EII(CB) component of the phosphoenolpyruvate-dependent sugar:phosphotransferase system and a putative regulatory protein, respectively. The authors suggest that for F. mortiferum, the products of malB and malH catalyse the phosphorylative translocation and intracellular hydrolysis of the five isomers of sucrose and of related alpha-linked glucosides. Genes homologous to malB and malH are present in both Klebsiella pneumoniae and the enterohaemorrhagic strain Escherichia coli O157:H7. Both these organisms grew well on sucrose, but only K. pneumoniae exhibited growth on the isomeric compounds.
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Affiliation(s)
- Andreas Pikis
- Department of Infectious Diseases, Children's National Medical Center, Washington DC 20010-2970, USA2
- Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4350, USA1
| | - Stefan Immel
- Institut für Organische Chemie, Technische Universität Darmstadt,D-64287 Darmstadt, Germany3
| | - Stanley A Robrish
- Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4350, USA1
| | - John Thompson
- Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4350, USA1
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Levander F, Andersson U, Rådström P. Physiological role of beta-phosphoglucomutase in Lactococcus lactis. Appl Environ Microbiol 2001; 67:4546-53. [PMID: 11571154 PMCID: PMC93201 DOI: 10.1128/aem.67.10.4546-4553.2001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A beta-phosphoglucomutase (beta-PGM) mutant of Lactococcus lactis subsp. lactis ATCC 19435 was constructed using a minimal integration vector and double-crossover recombination. The mutant and the wild-type strain were grown under controlled conditions with different sugars to elucidate the role of beta-PGM in carbohydrate catabolism and anabolism. The mutation did not significantly affect growth, product formation, or cell composition when glucose or lactose was used as the carbon source. With maltose or trehalose as the carbon source the wild-type strain had a maximum specific growth rate of 0.5 h(-1), while the deletion of beta-PGM resulted in a maximum specific growth rate of 0.05 h(-1) on maltose and no growth at all on trehalose. Growth of the mutant strain on maltose resulted in smaller amounts of lactate but more formate, acetate, and ethanol, and approximately 1/10 of the maltose was found as beta-glucose 1-phosphate in the medium. Furthermore, the beta-PGM mutant cells grown on maltose were considerably larger and accumulated polysaccharides which consisted of alpha-1,4-bound glucose units. When the cells were grown at a low dilution rate in a glucose and maltose mixture, the wild-type strain exhibited a higher carbohydrate content than when grown at higher growth rates, but still this content was lower than that in the beta-PGM mutant. In addition, significant differences in the initial metabolism of maltose and trehalose were found, and cell extracts did not digest free trehalose but only trehalose 6-phosphate, which yielded beta-glucose 1-phosphate and glucose 6-phosphate. This demonstrates the presence of a novel enzymatic pathway for trehalose different from that of maltose metabolism in L. lactis.
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Affiliation(s)
- F Levander
- Applied Microbiology, Center for Chemistry and Chemical Engineering, Lund Institute of Technology, Lund University, SE-221 00 Lund, Sweden
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Yamamoto H, Serizawa M, Thompson J, Sekiguchi J. Regulation of the glv operon in Bacillus subtilis: YfiA (GlvR) is a positive regulator of the operon that is repressed through CcpA and cre. J Bacteriol 2001; 183:5110-21. [PMID: 11489864 PMCID: PMC95387 DOI: 10.1128/jb.183.17.5110-5121.2001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Maltose metabolism and the regulation of the glv operon of Bacillus subtilis, comprising three genes, glvA (6-phospho-alpha-glucosidase), yfiA (now designated glvR), and glvC (EIICB transport protein), were investigated. Maltose dissimilation was dependent primarily upon the glv operon, and insertional inactivation of either glvA, glvR, or glvC markedly inhibited growth on the disaccharide. A second system (MalL) contributed to a minor extent to maltose metabolism. Northern blotting revealed two transcripts corresponding to a monocistronic mRNA of glvA and a polycistronic mRNA of glvA-glvR-glvC. Primer extension analysis showed that both transcripts started at the same base (G) located 26 bp upstream of the 5' end of glvA. When glvR was placed under control of the spac promoter, expression of the glv operon was dependent upon the presence of isopropyl-beta-D-thiogalactopyranoside (IPTG). In regulatory studies, the promoter sequence of the glv operon was fused to lacZ and inserted into the amyE locus, and the resultant strain (AMGLV) was then transformed with a citrate-controlled glvR plasmid, pHYCM2VR. When cultured in Difco sporulation medium containing citrate, this transformant [AMGLV(pHYCM2VR)] expressed LacZ activity, but synthesis of LacZ was repressed by glucose. In an isogenic strain, [AMGLVCR(pHYCM2VR)], except for a mutation in the sequence of a catabolite-responsive element (cre), LacZ activity was expressed in the presence of citrate and glucose. Insertion of a citrate-controlled glvR plasmid at the amyE locus of ccpA(+) and ccpA mutant organisms yielded strains AMCMVR and AMCMVRCC, respectively. In the presence of both glucose and citrate, AMCMVR failed to express the glv operon, whereas under the same conditions high-level expression of both mRNA transcripts was found in strain AMCMVRCC. Collectively, our findings suggest that GlvR (the product of the glvR gene) is a positive regulator of the glv operon and that glucose exerts its effect via catabolite repression requiring both CcpA and cre.
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Affiliation(s)
- H Yamamoto
- Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, Nagano 386-8567, Japan
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Thompson J, Robrish SA, Pikis A, Brust A, Lichtenthaler FW. Phosphorylation and metabolism of sucrose and its five linkage-isomeric alpha-D-glucosyl-D-fructoses by Klebsiella pneumoniae. Carbohydr Res 2001; 331:149-61. [PMID: 11322729 DOI: 10.1016/s0008-6215(01)00028-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Not only sucrose but the five isomeric alpha-D-glucosyl-D-fructoses trehalulose, turanose, maltulose, leucrose, and palatinose are utilized by Klebsiella pneumoniae as energy sources for growth, thereby undergoing phosphorylation by a phosphoenolpyruvate-dependent phosphotransferase system uniformly at 0-6 of the glucosyl moiety. Similarly, maltose, isomaltose, and maltitol, when exposed to these conditions, are phosphorylated regiospecifically at O-6 of their non-reducing glucose portion. The structures of these novel compounds have been established unequivocally by enzymatic analysis, acid hydrolysis, FAB negative-ion spectrometry, and 1H and 13C NMR spectroscopy. In cells of K. pneumoniae, hydrolysis of sucrose 6-phosphate is catalyzed by sucrose 6-phosphate hydrolase from Family 32 of the glycosylhydrolase superfamily. The five 6'-O-phosphorylated alpha-D-glucosyl-fructoses are hydrolyzed by an inducible (approximately 49-50 Kda) phospho-alpha-glucosidase from Family 4 of the glycosylhydrolase superfamily.
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Affiliation(s)
- J Thompson
- Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4350, USA.
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Abstract
The gram-positive bacterium Bacillus subtilisis capable of using numerous carbohydrates as single sources of carbon and energy. In this review, we discuss the mechanisms of carbon catabolism and its regulation. Like many other bacteria, B. subtilis uses glucose as the most preferred source of carbon and energy. Expression of genes involved in catabolism of many other substrates depends on their presence (induction) and the absence of carbon sources that can be well metabolized (catabolite repression). Induction is achieved by different mechanisms, with antitermination apparently more common in B. subtilis than in other bacteria. Catabolite repression is regulated in a completely different way than in enteric bacteria. The components mediating carbon catabolite repression in B. subtilis are also found in many other gram-positive bacteria of low GC content.
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Affiliation(s)
- J Stülke
- Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie, Biochemie und Genetik der Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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49
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Abstract
Insights into glycosidase mechanisms have come from X-ray crystallographic studies on complexes with substrate analogs and inhibitors, representing all the intermediate species along the reaction coordinate. Site-directed mutagenesis continues to play a significant role in understanding mechanisms, but is also proving important in generating glycosidases of modified mechanism or specificity.
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Affiliation(s)
- C S Rye
- University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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Marino M, Hoffmann T, Schmid R, Möbitz H, Jahn D. Changes in protein synthesis during the adaptation of Bacillus subtilis to anaerobic growth conditions. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 1):97-105. [PMID: 10658656 DOI: 10.1099/00221287-146-1-97] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
After a shift of Bacillus subtilis from aerobic to anaerobic growth conditions, nitrate ammonification and various fermentative processes replace oxygen-dependent respiration. Cell-free extracts prepared from wild-type B. subtilis and from mutants of the regulatory loci fnr and resDE grown under aerobic and various anaerobic conditions were compared by two-dimensional gel electrophoresis. Proteins involved in the adaptation process were identified by their N-terminal sequence. Induction of cytoplasmic lactate dehydrogenase (LctE) synthesis under anaerobic fermentative conditions was dependent on fnr and resDE. Anaerobic nitrate repression of LctE formation required fnr-mediated expression of narGHJI, encoding respiratory nitrate reductase. Anaerobic induction of the flavohaemoglobin Hmp required resDE and nitrite. The general anaerobic induction of ywfl, encoding a protein of unknown function, was modulated by resDE and fnr. The ywfl gene shares its upstream region with the pta gene, encoding the fermentative enzyme acetyl-CoA:orthophosphate acetyltransferase. Anaerobic repression of the synthesis of a potential membrane-associated NADH dehydrogenase (YjlD, Ndh), and anaerobic induction of fructose-1,6-bisphosphate aldolase (FbaA) and dehydrolipoamide dehydrogenase (PhdD, Lpd) formation, did not require fnr or resDE participation. Synthesis of glycerol kinase (GlpK) was decreased under anaerobic conditions. Finally, the effect of anaerobic stress induced by the immediate shift from aerobic to strictly anaerobic conditions was analysed. The induction of various systems for the utilization of alternative carbon sources such as inositol (IoIA, IoIG, IoIH, IoII), melibiose (MeIA) and 6-phospho-alpha-glucosides (GIvA) indicated a catabolite-response-like stress reaction.
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Affiliation(s)
- Marco Marino
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany1
| | - Tamara Hoffmann
- Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität Marburg, and Max-Planck-Institut für Terrestrische Mikrobiologie, Karl-von-Frisch-Str., 35043 Marburg, Germany2
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany1
| | - Roland Schmid
- Institut für Mikrobiologie, Universität Osnabrück, Barbarastr. 11, 49060 Osnabrück, Germany3
| | - Henrik Möbitz
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany1
| | - Dieter Jahn
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany1
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