1
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Sun X, Zhao J, Zhou X, Bei Q, Xia W, Zhao B, Zhang J, Jia Z. Salt tolerance-based niche differentiation of soil ammonia oxidizers. THE ISME JOURNAL 2022; 16:412-422. [PMID: 34389794 PMCID: PMC8776802 DOI: 10.1038/s41396-021-01079-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 07/20/2021] [Accepted: 07/26/2021] [Indexed: 02/03/2023]
Abstract
Ammonia oxidizers are key players in the global nitrogen cycle, yet little is known about their ecological performances and adaptation strategies for growth in saline terrestrial ecosystems. This study combined 13C-DNA stable-isotope probing (SIP) microcosms with amplicon and shotgun sequencing to reveal the composition and genomic adaptations of active ammonia oxidizers in a saline-sodic (solonetz) soil with high salinity and pH (20.9 cmolc exchangeable Na+ kg-1 soil and pH 9.64). Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) exhibited strong nitrification activities, although AOB performed most of the ammonia oxidation observed in the solonetz soil and in the farmland soil converted from solonetz soil. Members of the Nitrosococcus, which are more often associated with aquatic habitats, were identified as the dominant ammonia oxidizers in the solonetz soil with the first direct labeling evidence, while members of the Nitrosospira were the dominant ammonia oxidizers in the farmland soil, which had much lower salinity and pH. Metagenomic analysis of "Candidatus Nitrosococcus sp. Sol14", a new species within the Nitrosococcus lineage, revealed multiple genomic adaptations predicted to facilitate osmotic and pH homeostasis in this extreme habitat, including direct Na+ extrusion/H+ import and the ability to increase intracellular osmotic pressure by accumulating compatible solutes. Comparative genomic analysis revealed that variation in salt-tolerance mechanisms was the primary driver for the niche differentiation of ammonia oxidizers in saline-sodic soils. These results demonstrate how ammonia oxidizers can adapt to saline-sodic soil with excessive Na+ content and provide new insights on the nitrogen cycle in extreme terrestrial ecosystems.
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Affiliation(s)
- Xiangxin Sun
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Jun Zhao
- grid.15276.370000 0004 1936 8091Institute for Food and Agricultural Sciences (IFAS), Department of Microbiology & Cell Science, Fort Lauderdale Research and Education Center, University of Florida, Davie, FL USA
| | - Xue Zhou
- grid.257065.30000 0004 1760 3465College of Agricultural Science and Engineering, Hohai University, Nanjing, Jiangsu Province China
| | - Qicheng Bei
- grid.419554.80000 0004 0491 8361Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Weiwei Xia
- grid.260478.f0000 0000 9249 2313College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, Jiangsu Province China
| | - Bingzi Zhao
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Jiabao Zhang
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Zhongjun Jia
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
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2
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Alarico S, Nunes-Costa D, Silva A, Costa M, Macedo-Ribeiro S, Empadinhas N. A genuine mycobacterial thermophile: Mycobacterium hassiacum growth, survival and GpgS stability at near-pasteurization temperatures. MICROBIOLOGY-SGM 2021; 166:474-483. [PMID: 32100712 DOI: 10.1099/mic.0.000898] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mycobacterium hassiacum is so far the most thermophilic among mycobacteria as it grows optimally at 50 °C and up to 65 °C in a glycerol-based medium, as verified in this study. Since this and other nontuberculous mycobacteria (NTM) thrive in diverse natural and artificial environments, from where they may access and infect humans, we deemed essential to probe M. hassiacum resistance to heat, a strategy routinely used to control microbial growth in water-supply systems, as well as in the food and drink industries. In addition to possibly being a threat in its own right in rare occasions, M. hassiacum is also a good surrogate for studying other NTM species more often associated with opportunistic infection, namely Mycobacterium avium and Mycobacterium abscessus as well as their strictly pathogenic counterparts Mycobacterium tuberculosis and Mycobacterium leprae. In this regard, this thermophilic species is likely to be useful as a source of stable proteins that may provide more detailed structures of potential drug targets. Here, we investigate M. hassiacum growth at near-pasteurization temperatures and at different pHs and also characterize its thermostable glucosyl-3-phosphoglycerate synthase (GpgS), an enzyme considered essential for M. tuberculosis growth and associated with both nitrogen starvation and thermal stress in different NTM species.
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Affiliation(s)
- Susana Alarico
- IIIUC - Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal.,CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Daniela Nunes-Costa
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,PDBEB - PhD Programme in Biomedicine and Experimental Biology, Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Alexandra Silva
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Mafalda Costa
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Sandra Macedo-Ribeiro
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Nuno Empadinhas
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,IIIUC - Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
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3
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Taujale R, Venkat A, Huang LC, Zhou Z, Yeung W, Rasheed KM, Li S, Edison AS, Moremen KW, Kannan N. Deep evolutionary analysis reveals the design principles of fold A glycosyltransferases. eLife 2020; 9:54532. [PMID: 32234211 PMCID: PMC7185993 DOI: 10.7554/elife.54532] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/31/2020] [Indexed: 12/26/2022] Open
Abstract
Glycosyltransferases (GTs) are prevalent across the tree of life and regulate nearly all aspects of cellular functions. The evolutionary basis for their complex and diverse modes of catalytic functions remain enigmatic. Here, based on deep mining of over half million GT-A fold sequences, we define a minimal core component shared among functionally diverse enzymes. We find that variations in the common core and emergence of hypervariable loops extending from the core contributed to GT-A diversity. We provide a phylogenetic framework relating diverse GT-A fold families for the first time and show that inverting and retaining mechanisms emerged multiple times independently during evolution. Using evolutionary information encoded in primary sequences, we trained a machine learning classifier to predict donor specificity with nearly 90% accuracy and deployed it for the annotation of understudied GTs. Our studies provide an evolutionary framework for investigating complex relationships connecting GT-A fold sequence, structure, function and regulation. Carbohydrates are one of the major groups of large biological molecules that regulate nearly all aspects of life. Yet, unlike DNA or proteins, carbohydrates are made without a template to follow. Instead, these molecules are built from a set of sugar-based building blocks by the intricate activities of a large and diverse family of enzymes known as glycosyltransferases. An incomplete understanding of how glycosyltransferases recognize and build diverse carbohydrates presents a major bottleneck in developing therapeutic strategies for diseases associated with abnormalities in these enzymes. It also limits efforts to engineer these enzymes for biotechnology applications and biofuel production. Taujale et al. have now used evolutionary approaches to map the evolution of a major subset of glycosyltransferases from species across the tree of life to understand how these enzymes evolved such precise mechanisms to build diverse carbohydrates. First, a minimal structural unit was defined based on being shared among a group of over half a million unique glycosyltransferase enzymes with different activities. Further analysis then showed that the diverse activities of these enzymes evolved through the accumulation of mutations within this structural unit, as well as in much more variable regions in the enzyme that extend from the minimal unit. Taujale et al. then built an extended family tree for this collection of glycosyltransferases and details of the evolutionary relationships between the enzymes helped them to create a machine learning framework that could predict which sugar-containing molecules were the raw materials for a given glycosyltransferase. This framework could make predictions with nearly 90% accuracy based only on information that can be deciphered from the gene for that enzyme. These findings will provide scientists with new hypotheses for investigating the complex relationships connecting the genetic information about glycosyltransferases with their structures and activities. Further refinement of the machine learning framework may eventually enable the design of enzymes with properties that are desirable for applications in biotechnology.
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Affiliation(s)
- Rahil Taujale
- Institute of Bioinformatics, University of Georgia, Athens, Georgia.,Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia
| | - Aarya Venkat
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia
| | - Liang-Chin Huang
- Institute of Bioinformatics, University of Georgia, Athens, Georgia
| | - Zhongliang Zhou
- Department of Computer Science, University of Georgia, Athens, Georgia
| | - Wayland Yeung
- Institute of Bioinformatics, University of Georgia, Athens, Georgia
| | - Khaled M Rasheed
- Department of Computer Science, University of Georgia, Athens, Georgia
| | - Sheng Li
- Department of Computer Science, University of Georgia, Athens, Georgia
| | - Arthur S Edison
- Institute of Bioinformatics, University of Georgia, Athens, Georgia.,Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia.,Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia
| | - Kelley W Moremen
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia.,Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia
| | - Natarajan Kannan
- Institute of Bioinformatics, University of Georgia, Athens, Georgia.,Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia
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4
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Nunes-Costa D, Maranha A, Costa M, Alarico S, Empadinhas N. Glucosylglycerate metabolism, bioversatility and mycobacterial survival. Glycobiology 2016; 27:213-227. [DOI: 10.1093/glycob/cww132] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/14/2016] [Indexed: 12/17/2022] Open
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5
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Maranha A, Moynihan PJ, Miranda V, Correia Lourenço E, Nunes-Costa D, Fraga JS, José Barbosa Pereira P, Macedo-Ribeiro S, Ventura MR, Clarke AJ, Empadinhas N. Octanoylation of early intermediates of mycobacterial methylglucose lipopolysaccharides. Sci Rep 2015; 5:13610. [PMID: 26324178 PMCID: PMC4555173 DOI: 10.1038/srep13610] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 07/30/2015] [Indexed: 11/10/2022] Open
Abstract
Mycobacteria synthesize unique intracellular methylglucose lipopolysaccharides (MGLP) proposed to modulate fatty acid metabolism. In addition to the partial esterification of glucose or methylglucose units with short-chain fatty acids, octanoate was invariably detected on the MGLP reducing end. We have identified a novel sugar octanoyltransferase (OctT) that efficiently transfers octanoate to glucosylglycerate (GG) and diglucosylglycerate (DGG), the earliest intermediates in MGLP biosynthesis. Enzymatic studies, synthetic chemistry, NMR spectroscopy and mass spectrometry approaches suggest that, in contrast to the prevailing consensus, octanoate is not esterified to the primary hydroxyl group of glycerate but instead to the C6 OH of the second glucose in DGG. These observations raise important new questions about the MGLP reducing end architecture and about subsequent biosynthetic steps. Functional characterization of this unique octanoyltransferase, whose gene has been proposed to be essential for M. tuberculosis growth, adds new insights into a vital mycobacterial pathway, which may inspire new drug discovery strategies.
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Affiliation(s)
- Ana Maranha
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Patrick J. Moynihan
- Department of Molecular and Cellular Biology, University of Guelph, Ontario, Canada
| | - Vanessa Miranda
- ITQB – Instituto de Tecnologia Química Biológica, Universidade Nova de Lisboa, Portugal
| | - Eva Correia Lourenço
- ITQB – Instituto de Tecnologia Química Biológica, Universidade Nova de Lisboa, Portugal
| | - Daniela Nunes-Costa
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Joana S. Fraga
- IBMC – Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Pedro José Barbosa Pereira
- IBMC – Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Sandra Macedo-Ribeiro
- IBMC – Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - M. Rita Ventura
- ITQB – Instituto de Tecnologia Química Biológica, Universidade Nova de Lisboa, Portugal
| | - Anthony J. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Ontario, Canada
| | - Nuno Empadinhas
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
- III/UC– Instituto de Investigação Interdisciplinar, University of Coimbra, Portugal
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6
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Possner DDD, Claesson M, Guy JE. Structure of the Glycosyltransferase Ktr4p from Saccharomyces cerevisiae. PLoS One 2015; 10:e0136239. [PMID: 26296208 PMCID: PMC4546622 DOI: 10.1371/journal.pone.0136239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/30/2015] [Indexed: 11/18/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, members of the Kre2/Mnt1 protein family have been shown to be α-1,2-mannosyltransferases or α-1,2-mannosylphosphate transferases, utilising an Mn2+-coordinated GDP-mannose as the sugar donor and a variety of mannose derivatives as acceptors. Enzymes in this family are localised to the Golgi apparatus, and have been shown to be involved in both N- and O-linked glycosylation of newly-synthesised proteins, including cell wall glycoproteins. Our knowledge of the nine proteins in this family is however very incomplete at present. Only one family member, Kre2p/Mnt1p, has been studied by structural methods, and three (Ktr4p, Ktr5p, Ktr7p) are completely uncharacterised and remain classified only as putative glycosyltransferases. Here we use in vitro enzyme activity assays to provide experimental confirmation of the predicted glycosyltransferase activity of Ktr4p. Using GDP-mannose as the donor, we observe activity towards the acceptor methyl-α-mannoside, but little or no activity towards mannose or α-1,2-mannobiose. We also present the structure of the lumenal catalytic domain of S. cerevisiae Ktr4p, determined by X-ray crystallography to a resolution of 2.2 Å, and the complex of the enzyme with GDP to 1.9 Å resolution.
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Affiliation(s)
- Dominik D. D. Possner
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Tomtebodavägen 6, S 171-77, Stockholm, Sweden
| | - Magnus Claesson
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, S 106-91, Stockholm, Sweden
| | - Jodie E. Guy
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Tomtebodavägen 6, S 171-77, Stockholm, Sweden
- * E-mail:
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7
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Structure of mycobacterial maltokinase, the missing link in the essential GlgE-pathway. Sci Rep 2015; 5:8026. [PMID: 25619172 PMCID: PMC4306142 DOI: 10.1038/srep08026] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 01/02/2015] [Indexed: 02/04/2023] Open
Abstract
A novel four-step pathway identified recently in mycobacteria channels trehalose to glycogen synthesis and is also likely involved in the biosynthesis of two other crucial polymers: intracellular methylglucose lipopolysaccharides and exposed capsular glucan. The structures of three of the intervening enzymes - GlgB, GlgE, and TreS - were recently reported, providing the first templates for rational drug design. Here we describe the structural characterization of the fourth enzyme of the pathway, mycobacterial maltokinase (Mak), uncovering a eukaryotic-like kinase (ELK) fold, similar to methylthioribose kinases and aminoglycoside phosphotransferases. The 1.15 Å structure of Mak in complex with a non-hydrolysable ATP analog reveals subtle structural rearrangements upon nucleotide binding in the cleft between the N- and the C-terminal lobes. Remarkably, this new family of ELKs has a novel N-terminal domain topologically resembling the cystatin family of protease inhibitors. By interfacing with and restraining the mobility of the phosphate-binding region of the N-terminal lobe, Mak's unusual N-terminal domain might regulate its phosphotransfer activity and represents the most likely anchoring point for TreS, the upstream enzyme in the pathway. By completing the gallery of atomic-detail models of an essential pathway, this structure opens new avenues for the rational design of alternative anti-tubercular compounds.
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8
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Takahashi S, Furukawara M, Omae K, Tadokoro N, Saito Y, Abe K, Kera Y. A Highly Stable D-Amino Acid Oxidase of the Thermophilic Bacterium Rubrobacter xylanophilus. Appl Environ Microbiol 2014; 80:7219-29. [PMID: 25217016 PMCID: PMC4249180 DOI: 10.1128/aem.02193-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/09/2014] [Indexed: 01/31/2023] Open
Abstract
d-Amino acid oxidase (DAO) is a biotechnologically attractive enzyme that can be used in a variety of applications, but its utility is limited by its relatively poor stability. A search of a bacterial genome database revealed a gene encoding a protein homologous to DAO in the thermophilic bacterium Rubrobacter xylanophilus (RxDAO). The recombinant protein expressed in Escherichia coli was a monomeric protein containing noncovalently bound flavin adenine dinucleotide as a cofactor. This protein exhibited oxidase activity against neutral and basic d-amino acids and was significantly inhibited by a DAO inhibitor, benzoate, but not by any of the tested d-aspartate oxidase (DDO) inhibitors, thus indicating that the protein is DAO. RxDAO exhibited higher activities and affinities toward branched-chain d-amino acids, with the highest specific activity toward d-valine and catalytic efficiency (kcat/Km) toward d-leucine. Substrate inhibition was observed in the case of d-tyrosine. The enzyme had an optimum pH range and temperature of pH 7.5 to 10 and 65°C, respectively, and was stable between pH 5.0 and pH 8.0, with a T50 (the temperature at which 50% of the initial enzymatic activity is lost) of 64°C. No loss of enzyme activity was observed after a 1-week incubation period at 30°C. This enzyme was markedly inactivated by phenylmethylsulfonyl fluoride but not by thiol-modifying reagents and diethyl pyrocarbonate, which are known to inhibit certain DAOs. These results demonstrated that RxDAO is a highly stable DAO and suggested that this enzyme may be valuable for practical applications, such as the determination and quantification of branched-chain d-amino acids, and as a scaffold to generate a novel DAO via protein engineering.
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Affiliation(s)
- Shouji Takahashi
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Makoto Furukawara
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Keishi Omae
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Namiho Tadokoro
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Yayoi Saito
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Katsumasa Abe
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
| | - Yoshio Kera
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan
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9
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Kumar G, Guan S, Frantom PA. Biochemical characterization of the retaining glycosyltransferase glucosyl-3-phosphoglycerate synthase from Mycobacterium tuberculosis. Arch Biochem Biophys 2014; 564:120-7. [PMID: 25317963 DOI: 10.1016/j.abb.2014.10.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/03/2014] [Accepted: 10/06/2014] [Indexed: 11/15/2022]
Abstract
Glucosyl-3-phosphoglycerate synthase (GpgS) catalyzes the first step in the biosynthesis of glucosyl glycerate, the putative precursor used in building methylated polysaccharides in mycobacteria. Enzymes from Mycobacterium tuberculosis (MtGpgS) and related species have been structurally characterized and subjected to basic kinetic analyses, but more in-depth kinetic analysis is currently lacking. Dead-end inhibition studies with MtGpgS suggest an ordered kinetic mechanism with 3-phosphoglycerate (3-PGA) binding first, followed by UDP-glucose, in contrast to previous reports. At higher concentrations, 3-PGA exhibits competitive substrate inhibition vs. UDP-glucose, suggesting 3-PGA can bind to either binding site on the enzyme. Parabolic noncompetitive inhibition plots by a 3-PGA analog also support this conclusion. The effect of varying pH on the catalytic parameters indicates single ionizable residue involved catalysis (pKa=6.3) that must be deprotonated for full activity. A solvent kinetic isotope effect of 2.0±0.3 on kcat is consistent with a proton in flight during the rate-determining step. Site-directed mutagenesis studies identify several residues critical for interactions with substrates. Although the residues are conserved among other glycosyltransferase families catalyzing similar reactions, the effect of substitutions varies between families suggesting that conserved areas play different catalytic roles in each family.
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Affiliation(s)
- Garima Kumar
- Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, AL 35487, USA
| | - Siqi Guan
- Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, AL 35487, USA
| | - Patrick A Frantom
- Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, AL 35487, USA.
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10
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Borges N, Jorge CD, Gonçalves LG, Gonçalves S, Matias PM, Santos H. Mannosylglycerate: structural analysis of biosynthesis and evolutionary history. Extremophiles 2014; 18:835-52. [PMID: 25108362 DOI: 10.1007/s00792-014-0661-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/18/2014] [Indexed: 11/26/2022]
Abstract
Halophilic and halotolerant microorganisms adapted to thrive in hot environments accumulate compatible solutes that usually have a negative charge either associated with a carboxylic group or a phosphodiester unit. Mannosylglycerate (MG) has been detected in several members of (hyper)thermophilic bacteria and archaea, in which it responds primarily to osmotic stress. The outstanding ability of MG to stabilize protein structure in vitro as well as in vivo has been convincingly demonstrated. These findings led to an increasingly supported link between MG and microbial adaptation to high temperature. However, the accumulation of MG in many red algae has been known for a long time, and the peculiar distribution of MG in such distant lineages was intriguing. Knowledge on the biosynthetic machinery together with the rapid expansion of genome databases allowed for structural and phylogenetic analyses and provided insight into the distribution of MG. The two pathways for MG synthesis have distinct evolutionary histories and physiological roles: in red algae MG is synthesised exclusively via the single-step pathway and most probably is unrelated with stress protection. In contrast, the two-step pathway is strongly associated with osmoadaptation in (hyper)thermophilic prokaryotes. The phylogenetic analysis of the two-step pathway also reveals a second cluster composed of fungi and mesophilic bacteria, but MG has not been demonstrated in members of this cluster; we propose that the synthase is part of a more complex pathway directed at the synthesis of yet unknown molecules containing the mannosyl-glyceryl unit.
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Affiliation(s)
- Nuno Borges
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República-EAN, 2780-157, Oeiras, Portugal
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11
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Cunha S, d'Avó AF, Mingote A, Lamosa P, da Costa MS, Costa J. Mannosylglucosylglycerate biosynthesis in the deep-branching phylum Planctomycetes: characterization of the uncommon enzymes from Rhodopirellula baltica. Sci Rep 2014; 3:2378. [PMID: 23921581 PMCID: PMC3736172 DOI: 10.1038/srep02378] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 07/23/2013] [Indexed: 11/24/2022] Open
Abstract
The biosynthetic pathway for the rare compatible solute mannosylglucosylglycerate (MGG) accumulated by Rhodopirellula baltica, a marine member of the phylum Planctomycetes, has been elucidated. Like one of the pathways used in the thermophilic bacterium Petrotoga mobilis, it has genes coding for glucosyl-3-phosphoglycerate synthase (GpgS) and mannosylglucosyl-3-phosphoglycerate (MGPG) synthase (MggA). However, unlike Ptg. mobilis, the mesophilic R. baltica uses a novel and very specific MGPG phosphatase (MggB). It also lacks a key enzyme of the alternative pathway in Ptg. mobilis – the mannosylglucosylglycerate synthase (MggS) that catalyses the condensation of glucosylglycerate with GDP-mannose to produce MGG. The R. baltica enzymes GpgS, MggA, and MggB were expressed in E. coli and characterized in terms of kinetic parameters, substrate specificity, temperature and pH dependence. This is the first characterization of genes and enzymes for the synthesis of compatible solutes in the phylum Planctomycetes and for the synthesis of MGG in a mesophile.
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Affiliation(s)
- Sofia Cunha
- Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
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12
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A new bacterial hydrolase specific for the compatible solutes α-d-mannopyranosyl-(1→2)-d-glycerate and α-d-glucopyranosyl-(1→2)-d-glycerate. Enzyme Microb Technol 2013; 52:77-83. [DOI: 10.1016/j.enzmictec.2012.10.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 10/19/2012] [Accepted: 10/23/2012] [Indexed: 11/21/2022]
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13
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Bell JA, Ho KL, Farid R. Significant reduction in errors associated with nonbonded contacts in protein crystal structures: automated all-atom refinement with PrimeX. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:935-52. [PMID: 22868759 PMCID: PMC3413210 DOI: 10.1107/s0907444912017453] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 04/19/2012] [Indexed: 11/12/2022]
Abstract
All-atom models are essential for many applications in molecular modeling and computational chemistry. Nonbonded atomic contacts much closer than the sum of the van der Waals radii of the two atoms (clashes) are commonly observed in such models derived from protein crystal structures. A set of 94 recently deposited protein structures in the resolution range 1.5-2.8 Å were analyzed for clashes by the addition of all H atoms to the models followed by optimization and energy minimization of the positions of just these H atoms. The results were compared with the same set of structures after automated all-atom refinement with PrimeX and with nonbonded contacts in protein crystal structures at a resolution equal to or better than 0.9 Å. The additional PrimeX refinement produced structures with reasonable summary geometric statistics and similar R(free) values to the original structures. The frequency of clashes at less than 0.8 times the sum of van der Waals radii was reduced over fourfold compared with that found in the original structures, to a level approaching that found in the ultrahigh-resolution structures. Moreover, severe clashes at less than or equal to 0.7 times the sum of atomic radii were reduced 15-fold. All-atom refinement with PrimeX produced improved crystal structure models with respect to nonbonded contacts and yielded changes in structural details that dramatically impacted on the interpretation of some protein-ligand interactions.
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Affiliation(s)
- Jeffrey A. Bell
- Schrödinger, 120 West 45th Street, 17th Floor, New York, NY 10036, USA
| | - Kenneth L. Ho
- Schrödinger, 120 West 45th Street, 17th Floor, New York, NY 10036, USA
| | - Ramy Farid
- Schrödinger, 120 West 45th Street, 17th Floor, New York, NY 10036, USA
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Urresti S, Albesa-Jové D, Schaeffer F, Pham HT, Kaur D, Gest P, van der Woerd MJ, Carreras-González A, López-Fernández S, Alzari PM, Brennan PJ, Jackson M, Guerin ME. Mechanistic insights into the retaining glucosyl-3-phosphoglycerate synthase from mycobacteria. J Biol Chem 2012; 287:24649-61. [PMID: 22637481 DOI: 10.1074/jbc.m112.368191] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Considerable progress has been made in recent years in our understanding of the structural basis of glycosyl transfer. Yet the nature and relevance of the conformational changes associated with substrate recognition and catalysis remain poorly understood. We have focused on the glucosyl-3-phosphoglycerate synthase (GpgS), a "retaining" enzyme, that initiates the biosynthetic pathway of methylglucose lipopolysaccharides in mycobacteria. Evidence is provided that GpgS displays an unusually broad metal ion specificity for a GT-A enzyme, with Mg(2+), Mn(2+), Ca(2+), Co(2+), and Fe(2+) assisting catalysis. In the crystal structure of the apo-form of GpgS, we have observed that a flexible loop adopts a double conformation L(A) and L(I) in the active site of both monomers of the protein dimer. Notably, the L(A) loop geometry corresponds to an active conformation and is conserved in two other relevant states of the enzyme, namely the GpgS·metal·nucleotide sugar donor and the GpgS·metal·nucleotide·acceptor-bound complexes, indicating that GpgS is intrinsically in a catalytically active conformation. The crystal structure of GpgS in the presence of Mn(2+)·UDP·phosphoglyceric acid revealed an alternate conformation for the nucleotide sugar β-phosphate, which likely occurs upon sugar transfer. Structural, biochemical, and biophysical data point to a crucial role of the β-phosphate in donor and acceptor substrate binding and catalysis. Altogether, our experimental data suggest a model wherein the catalytic site is essentially preformed, with a few conformational changes of lateral chain residues as the protein proceeds along the catalytic cycle. This model of action may be applicable to a broad range of GT-A glycosyltransferases.
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Affiliation(s)
- Saioa Urresti
- Unidad de Biofísica, Centro Mixto Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibertsitatea, Barrio Sarriena s/n, Leioa, Bizkaia, 48940, Spain
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Mendes V, Maranha A, Alarico S, da Costa MS, Empadinhas N. Mycobacterium tuberculosis Rv2419c, the missing glucosyl-3-phosphoglycerate phosphatase for the second step in methylglucose lipopolysaccharide biosynthesis. Sci Rep 2011; 1:177. [PMID: 22355692 PMCID: PMC3240985 DOI: 10.1038/srep00177] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 11/15/2011] [Indexed: 11/13/2022] Open
Abstract
Mycobacteria synthesize intracellular methylglucose lipopolysaccharides (MGLP) proposed to regulate fatty acid synthesis. Although their structures have been elucidated, the identity of most biosynthetic genes remains unknown. The first step in MGLP biosynthesis is catalyzed by a glucosyl-3-phosphoglycerate synthase (GpgS, Rv1208 in Mycobacterium tuberculosis H37Rv). However, a typical glucosyl-3-phosphoglycerate phosphatase (GpgP, EC3.1.3.70) for dephosphorylation of glucosyl-3-phosphoglycerate to glucosylglycerate, was absent from mycobacterial genomes. We purified the native GpgP from Mycobacterium vanbaalenii and identified the corresponding gene deduced from amino acid sequences by mass spectrometry. The M. tuberculosis ortholog (Rv2419c), annotated as a putative phosphoglycerate mutase (PGM, EC5.4.2.1), was expressed and functionally characterized as a new GpgP. Regardless of the high specificity for glucosyl-3-phosphoglycerate, the mycobacterial GpgP is not a sequence homolog of known isofunctional GpgPs. The assignment of a new function in M. tuberculosis genome expands our understanding of this organism's genetic repertoire and of the early events in MGLP biosynthesis.
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Affiliation(s)
- Vítor Mendes
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
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