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Hartke J, Ceron-Noriega A, Stoldt M, Sistermans T, Kever M, Fuchs J, Butter F, Foitzik S. Long live the host! Proteomic analysis reveals possible strategies for parasitic manipulation of its social host. Mol Ecol 2023; 32:5877-5889. [PMID: 37795937 DOI: 10.1111/mec.17155] [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: 05/03/2023] [Revised: 09/15/2023] [Accepted: 09/19/2023] [Indexed: 10/06/2023]
Abstract
Parasites with complex life cycles often manipulate the phenotype of their intermediate hosts to increase the probability of transmission to their definitive hosts. Infection with Anomotaenia brevis, a cestode that uses Temnothorax nylanderi ants as intermediate hosts, leads to a multiple-fold extension of host lifespan and to changes in behaviour, morphology and colouration. The mechanisms behind these changes are unknown, as is whether the increased longevity is achieved through parasite manipulation. Here, we demonstrate that the parasite releases proteins into its host with functions that might explain the observed changes. These parasitic proteins make up a substantial portion of the proteome of the hosts' haemolymph, and thioredoxin peroxidase and superoxide dismutase, two antioxidants, exhibited the highest abundances among them. The largest part of the secreted proteins could not be annotated, indicating they are either novel or severely altered during recent coevolution to function in host manipulation. We also detected shifts in the hosts' proteome with infection, in particular an overabundance of vitellogenin-like A in infected ants, a protein that regulates division of labour in Temnothorax ants, which could explain the observed behavioural changes. Our results thus suggest two different strategies that might be employed by this parasite to manipulate its host: secreting proteins with immediate influence on the host's phenotype and altering the host's translational activity. Our findings highlight the intricate molecular interplay required to influence the phenotype of a host and point to potential signalling pathways and genes involved in parasite-host communication.
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Affiliation(s)
- Juliane Hartke
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | | | - Marah Stoldt
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Tom Sistermans
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Marion Kever
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Jenny Fuchs
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Falk Butter
- Institute of Molecular Biology, Mainz, Germany
| | - Susanne Foitzik
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
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2
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The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms. Appl Environ Microbiol 2022; 88:e0022222. [PMID: 35862683 PMCID: PMC9317898 DOI: 10.1128/aem.00222-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Photobacterium damselae comprises two subspecies, P. damselae subsp. damselae and P. damselae subsp. piscicida, that contrast remarkably despite their taxonomic relationship. The former is opportunistic and free-living but can cause disease in compromised individuals from a broad diversity of taxa, while the latter is a highly specialized, primary fish pathogen. Here, we employ new closed curated genome assemblies from Australia to estimate the global phylogenetic structure of the species P. damselae. We identify genes responsible for the shift from an opportunist to a host-adapted fish pathogen, potentially via an arthropod vector as fish-to-fish transmission was not achieved in repeated cohabitation challenges despite high virulence for Seriola lalandi. Acquisition of ShdA adhesin and of thiol peroxidase may have allowed the environmental, generalist ancestor to colonize zooplankton and to occasionally enter in fish host sentinel cells. As dependence on the host has increased, P. damselae has lost nonessential genes, such as those related to nitrite and sulfite reduction, urea degradation, a type 6 secretion system (T6SS) and several toxin-antitoxin (TA) systems. Similar to the evolution of Yersinia pestis, the loss of urease may be the crucial event that allowed the pathogen to stably colonize zooplankton vectors. Acquisition of host-specific genes, such as those required to form a sialic acid capsule, was likely necessary for the emergent P. damselae subsp. piscicida to become a highly specialized, facultative intracellular fish pathogen. Processes that have shaped P. damselae subsp. piscicida from subsp. damselae are similar to those underlying evolution of Yersinia pestis from Y. pseudotuberculosis. IMPORTANCEPhotobacterium damselae subsp. damselae is a ubiquitous marine bacterium and opportunistic pathogen of compromised hosts of diverse taxa. In contrast, its sister subspecies P. damselae subsp. piscicida (Pdp) is highly virulent in fish. Pdp has evolved from a single subclade of Pdd through gene loss and acquisition. We show that fish-to-fish transmission does not occur in repeated infection models in the primary host, Seriola lalandi, and present genomic evidence for vector-borne transmission, potentially via zooplankton. The broad genomic changes from generalist Pdd to specialist Pdp parallel those of the environmental opportunist Yersinia pseudotuberculosis to vector-borne plague bacterium Y. pestis and demonstrate that evolutionary processes in bacterial pathogens are universal between the terrestrial and marine biosphere.
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Matthews MM, McArthur JB, Li Y, Yu H, Chen X, Fisher AJ. Catalytic Cycle of Neisseria meningitidis CMP-Sialic Acid Synthetase Illustrated by High-Resolution Protein Crystallography. Biochemistry 2019; 59:3157-3168. [PMID: 31583886 DOI: 10.1021/acs.biochem.9b00517] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytidine 5'-monophosphate (CMP)-sialic acid synthetase (CSS) is an essential enzyme involved in the biosynthesis of carbohydrates and glycoconjugates containing sialic acids, a class of α-keto acids that are generally terminal key recognition residues by many proteins that play important biological and pathological roles. The CSS from Neisseria meningitidis (NmCSS) has been commonly used with other enzymes such as sialic acid aldolase and/or sialyltransferase in synthesizing a diverse array of compounds containing sialic acid or its naturally occurring and non-natural derivatives. To better understand its catalytic mechanism and substrate promiscuity, four NmCSS crystal structures trapped at various stages of the catalytic cycle with bound substrates, substrate analogues, and products have been obtained and are presented here. These structures suggest a mechanism for an "open" and "closed" conformational transition that occurs as sialic acid binds to the NmCSS/cytidine-5'-triphosphate (CTP) complex. The closed conformation positions critical residues to help facilitate the nucleophilic attack of sialic acid C2-OH to the α-phosphate of CTP, which is also aided by two observed divalent cations. Product formation drives the active site opening, promoting the release of products.
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Affiliation(s)
- Melissa M Matthews
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - John B McArthur
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Yanhong Li
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Hai Yu
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Xi Chen
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Andrew J Fisher
- Department of Chemistry, University of California, Davis, California 95616, United States.,Department of Molecular and Cellular Biology, University of California, Davis, California 95616, United States
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4
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Bose S, Purkait D, Joseph D, Nayak V, Subramanian R. Structural and functional characterization of CMP-N-acetylneuraminate synthetase from Vibrio cholerae. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2019; 75:564-577. [PMID: 31205019 PMCID: PMC6580227 DOI: 10.1107/s2059798319006831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 05/13/2019] [Indexed: 11/10/2022]
Abstract
CMP-N-acetylneuraminate synthetase (CMAS) is a key enzyme in the sialic acid incorporation pathway and plays a crucial role in the virulence and survival of several pathogenic bacteria. Here, the structural and functional properties of CMAS from the pathogenic bacterium Vibrio cholerae are reported. Upon CDP binding, a partial domain closure is observed that was previously unreported in homologous structures. Kinetic studies reveal that the enzyme shows substrate promiscuity and can activate both Neu5Ac and Neu5Gc. Several pathogenic bacteria utilize sialic acid, including host-derived N-acetylneuraminic acid (Neu5Ac), in at least two ways: they use it as a nutrient source and as a host-evasion strategy by coating themselves with Neu5Ac. Given the significant role of sialic acid in pathogenesis and host-gut colonization by various pathogenic bacteria, including Neisseria meningitidis, Haemophilus influenzae, Pasteurella multocida and Vibrio cholerae, several enzymes of the sialic acid catabolic, biosynthetic and incorporation pathways are considered to be potential drug targets. In this work, findings on the structural and functional characterization of CMP-N-acetylneuraminate synthetase (CMAS), a key enzyme in the incorporation pathway, from Vibrio cholerae are reported. CMAS catalyzes the synthesis of CMP-sialic acid by utilizing CTP and sialic acid. Crystal structures of the apo and the CDP-bound forms of the enzyme were determined, which allowed the identification of the metal cofactor Mg2+ in the active site interacting with CDP and the invariant Asp215 residue. While open and closed structural forms of the enzyme from eukaryotic and other bacterial species have already been characterized, a partially closed structure of V. cholerae CMAS (VcCMAS) observed upon CDP binding, representing an intermediate state, is reported here. The kinetic data suggest that VcCMAS is capable of activating the two most common sialic acid derivatives, Neu5Ac and Neu5Gc. Amino-acid sequence and structural comparison of the active site of VcCMAS with those of eukaryotic and other bacterial counterparts reveal a diverse hydrophobic pocket that interacts with the C5 substituents of sialic acid. Analyses of the thermodynamic signatures obtained from the binding of the nucleotide (CTP) and the product (CMP-sialic acid) to VcCMAS provide fundamental information on the energetics of the binding process.
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Affiliation(s)
- Sucharita Bose
- Institute for Stem Cell Science and Regenerative Medicine, GKVK Post, Bellary Road, Bangalore 560 065, India
| | - Debayan Purkait
- Institute for Stem Cell Science and Regenerative Medicine, GKVK Post, Bellary Road, Bangalore 560 065, India
| | - Deepthi Joseph
- Institute for Stem Cell Science and Regenerative Medicine, GKVK Post, Bellary Road, Bangalore 560 065, India
| | - Vinod Nayak
- Institute for Stem Cell Science and Regenerative Medicine, GKVK Post, Bellary Road, Bangalore 560 065, India
| | - Ramaswamy Subramanian
- Institute for Stem Cell Science and Regenerative Medicine, GKVK Post, Bellary Road, Bangalore 560 065, India
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Nontypeable Haemophilus influenzae Has Evolved Preferential Use of N-Acetylneuraminic Acid as a Host Adaptation. mBio 2019; 10:mBio.00422-19. [PMID: 31064827 PMCID: PMC6509186 DOI: 10.1128/mbio.00422-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Host-adapted bacterial pathogens such as NTHi cannot survive out of their host environment and have evolved host-specific mechanisms to obtain nutrients and evade the immune response. Relatively few of these host adaptations have been characterized at the molecular level. NTHi utilizes sialic acid as a nutrient and also incorporates this sugar into LOS, which is important in biofilm formation and immune evasion. In the present study, we showed that NTHi has evolved to preferentially utilize the Neu5Ac form of sialic acid. This adaptation is due to the substrate preference of the enzyme CMP-Neu5Ac synthetase, which synthesizes the activated form of Neu5Ac for macromolecule biosynthesis. This adaptation allows NTHi to evade killing by a human antibody response against the nonhuman sialic acid Neu5Gc. Nontypeable Haemophilus influenzae (NTHi) is a Gram-negative bacterial pathogen that is adapted exclusively to human hosts. NTHi utilizes sialic acid from the host as a carbon source and as a terminal sugar on the outer membrane glycolipid lipooligosaccharide (LOS). Sialic acid expressed on LOS is critical in NTHi biofilm formation and immune evasion. There are two major forms of sialic acids in most mammals, N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), the latter of which is derived from Neu5Ac. Humans lack the enzyme to convert Neu5Ac to Neu5Gc and do not express Neu5Gc in normal tissues; instead, Neu5Gc is recognized as a foreign antigen. A recent study showed that dietary Neu5Gc can be acquired by NTHi colonizing humans and then presented on LOS, which acts as an antigen for the initial induction of anti-Neu5Gc antibodies. Here we examined Neu5Gc uptake and presentation on NTHi LOS. We show that, although Neu5Gc and Neu5Ac are utilized equally well as sole carbon sources, Neu5Gc is not incorporated efficiently into LOS. When equal amounts of Neu5Gc and Neu5Ac are provided in culture media, there is ∼4-fold more Neu5Ac incorporated into LOS, suggesting a bias in a step of the LOS biosynthetic pathway. CMP-Neu5Ac synthetase (SiaB) was shown to have ∼4,000-fold-higher catalytic efficiency for Neu5Ac than for Neu5Gc. These data suggest that NTHi has adapted preferential utilization of Neu5Ac, thus avoiding presentation of the nonhuman Neu5Gc in the bacterial cell surface. The selective pressure for this adaptation may represent the human antibody response to the Neu5Gc xenoantigen.
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6
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Sellmeier M, Weinhold B, Münster-Kühnel A. CMP-Sialic Acid Synthetase: The Point of Constriction in the Sialylation Pathway. Top Curr Chem (Cham) 2015; 366:139-67. [PMID: 24141690 DOI: 10.1007/128_2013_477] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Sialoglycoconjugates form the outermost layer of animal cells and play a crucial role in cellular communication processes. An essential step in the biosynthesis of sialylated glycoconjugates is the activation of sialic acid to the monophosphate diester CMP-sialic acid. Only the activated sugar is transported into the Golgi apparatus and serves as a substrate for the linkage-specific sialyltransferases. Interference with sugar activation abolishes sialylation and is embryonic lethal in mammals. In this chapter we focus on the enzyme catalyzing the activation of sialic acid, the CMP-sialic acid synthetase (CMAS), and compare the enzymatic properties of CMASs isolated from different species. Information concerning the reaction mechanism and active site architecture is included. Moreover, the unusual nuclear localization of vertebrate CMASs as well as the biotechnological application of bacterial CMAS enzymes is addressed.
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Affiliation(s)
- Melanie Sellmeier
- Institute for Cellular Chemistry, Hannover Medical School (MHH), Hannover, 30625, Germany
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A CMP-N-acetylneuraminic Acid Synthetase Purified from a Marine Bacterium,Photobacterium leiognathiJT-SHIZ-145. Biosci Biotechnol Biochem 2014; 75:47-53. [DOI: 10.1271/bbb.100506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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8
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Han NS, Kim TJ, Park YC, Kim J, Seo JH. Biotechnological production of human milk oligosaccharides. Biotechnol Adv 2012; 30:1268-78. [DOI: 10.1016/j.biotechadv.2011.11.003] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/24/2011] [Accepted: 11/08/2011] [Indexed: 01/13/2023]
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9
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Sialic acid metabolism and sialyltransferases: natural functions and applications. Appl Microbiol Biotechnol 2012; 94:887-905. [PMID: 22526796 DOI: 10.1007/s00253-012-4040-1] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 03/16/2012] [Accepted: 03/16/2012] [Indexed: 12/17/2022]
Abstract
Sialic acids are a family of negatively charged monosaccharides which are commonly presented as the terminal residues in glycans of the glycoconjugates on eukaryotic cell surface or as components of capsular polysaccharides or lipooligosaccharides of some pathogenic bacteria. Due to their important biological and pathological functions, the biosynthesis, activation, transfer, breaking down, and recycle of sialic acids are attracting increasing attention. The understanding of the sialic acid metabolism in eukaryotes and bacteria leads to the development of metabolic engineering approaches for elucidating the important functions of sialic acid in mammalian systems and for large-scale production of sialosides using engineered bacterial cells. As the key enzymes in biosynthesis of sialylated structures, sialyltransferases have been continuously identified from various sources and characterized. Protein crystal structures of seven sialyltransferases have been reported. Wild-type sialyltransferases and their mutants have been applied with or without other sialoside biosynthetic enzymes for producing complex sialic acid-containing oligosaccharides and glycoconjugates. This mini-review focuses on current understanding and applications of sialic acid metabolism and sialyltransferases.
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10
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Wong JH, Sahni U, Li Y, Chen X, Gervay-Hague J. Synthesis of sulfone-based nucleotide isosteres: identification of CMP-sialic acid synthetase inhibitors. Org Biomol Chem 2008; 7:27-9. [PMID: 19081938 DOI: 10.1039/b819155g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A modular replacement approach to the synthesis of sulfo-nucleotide analogs prepared from condensation of nucleoside aldehydes with bis phosphonate Horner-Wadsworth-Emmons reagents is disclosed. These analogs were shown to be inhibitors of Neisseria meningitidis CSS (NmCSS), which is a key enzyme in the biosynthesis of the capsular polysaccharides required for bacterial infection.
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Affiliation(s)
- Jessica H Wong
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA, USA
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11
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Mizanur RM, Pohl NL. Bacterial CMP-sialic acid synthetases: production, properties, and applications. Appl Microbiol Biotechnol 2008; 80:757-65. [PMID: 18716769 DOI: 10.1007/s00253-008-1643-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 07/25/2008] [Accepted: 07/30/2008] [Indexed: 12/01/2022]
Abstract
Sialic acids are abundant nine-carbon sugars expressed terminally on glycoconjugates of eukaryotic cells and are crucial for a variety of cell biological functions such as cell-cell adhesion, intracellular signaling, and in regulation of glycoproteins stability. In bacteria, N-acetylneuraminic acid (Neu5Ac) polymers are important virulence factors. Cytidine 5'-monophosphate (CMP)-N-acetylneuraminic acid synthetase (CSS; EC 2.7.7.43), the key enzyme that synthesizes CMP-N-acetylneuraminic acid, the donor molecule for numerous sialyltransferase reactions, is present in both prokaryotes and eukaryotic systems. Herein, we emphasize the source, function, and biotechnological applications of CSS enzymes from bacterial sources. To date, only a few CSS from pathogenic bacterial species such as Neisseria meningitidis, Escherichia coli, group B streptococci, Haemophilus ducreyi, and Pasteurella hemolytica and an enzyme from nonpathogenic bacterium, Clostridium thermocellum, have been described. Overall, the enzymes from both Gram-positive and Gram-negative bacteria share common catalytic properties such as their dependency on divalent cation, temperature and pH profiles, and catalytic mechanisms. The enzymes, however, can be categorized as smaller and larger enzymes depending on their molecular weight. The larger enzymes in some cases are bifunctional; they have exhibited acetylhydrolase activity in addition to their sugar nucleotidyltransferase activity. The CSSs are important enzymes for the chemoenzymatic synthesis of various sialooligosaccharides of significance in biotechnology.
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Affiliation(s)
- Rahman M Mizanur
- Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
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Mizanur RM, Pohl NL. Cloning and characterization of a heat-stable CMP-N-acylneuraminic acid synthetase from Clostridium thermocellum. Appl Microbiol Biotechnol 2007; 76:827-34. [PMID: 17602221 DOI: 10.1007/s00253-007-1053-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2007] [Revised: 05/15/2007] [Accepted: 05/23/2007] [Indexed: 10/23/2022]
Abstract
In this study, we report the cloning, recombinant expression, and biochemical characterization of a heat-stable CMP-N-acylneuraminic acid (NeuAc) synthetase from Clostridium thermocellum ATCC 27405. A high throughput electrospray ionization mass spectrometry (ESI-MS)-based assay demonstrates that the enzyme has an absolute requirement for a divalent cation for activity and reaches maximum activity in the presence of 10 mM Mn(2+). The enzyme is active at pH 8-13 in Tris-HCl buffer and at 37-60 degrees C, and maximum activity is observed at pH 9.5 and 50 degrees C in the presence of 0.2 mM dithiothreitol. In addition to NeuAc, the enzyme also accepts the analog N-glycolylneuraminic acid (NeuGc) as a substrate. The apparent Michaelis constants for cytidine triphosphate and NeuAc or NeuGc are 240 +/- 20, 130 +/- 10, and 160 +/- 10 microM, respectively, with corresponding turnover numbers of 3.33, 2.25, and 1.66 s(-1), respectively. An initial velocity study of the enzymatic reaction indicates an ordered bi-bi catalytic mechanism. In addition to demonstration of a thermostable and substrate-tolerant enzyme, confirmation of the biochemical function of a gene for CMP-NeuAc synthetase in C. thermocellum also opens the question of the biological function of CMP-NeuAc in such nonpathogenic microorganisms.
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Affiliation(s)
- Rahman M Mizanur
- Department of Chemistry and The Plant Sciences Institute, Iowa State University, Ames, IA, 50011, USA.
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13
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Bravo IG, Reglero A. Application of a normalised plot to the study of ter ter enzyme systems. Biochimie 2004; 86:463-9. [PMID: 15308335 DOI: 10.1016/j.biochi.2004.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2003] [Accepted: 06/17/2004] [Indexed: 11/30/2022]
Abstract
The kinetic characterisation of multisubstrate systems is not a trivial task. Common approaches simplify the experimental procedures by sequentially fixing saturating concentrations of different substrates/products, thereby attempting to isolate the influence of the varying molecule. Even after such tedious work, only apparent Km values can be determined, preventing serious comparison among differential substrate behaviours. Moreover, the choice among rival kinetic models is not statistically guaranteed; instead, classical tools such as re-plots continue to be used. Here, we report the application of a normalisation of kinetic data, formerly applied to simpler systems, to the description of ter ter systems. This data treatment is able to provide true Km values and a reliable description of the system, at the same time reducing the experimental work and statistically supporting the choice of kinetic schemes.
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Affiliation(s)
- Ignacio G Bravo
- Deustches Krebsforschungszentrum, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany.
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14
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Liu G, Jin C, Jin C. CMP-N-acetylneuraminic acid synthetase from Escherichia coli K1 is a bifunctional enzyme: identification of minimal catalytic domain for synthetase activity and novel functional domain for platelet-activating factor acetylhydrolase activity. J Biol Chem 2004; 279:17738-49. [PMID: 14960566 DOI: 10.1074/jbc.m400143200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli CMP-NeuAc synthetase (EC 2.7.7.43) catalyzes the synthesis of CMP-NeuAc from CTP and NeuAc, which is essential for the formation of capsule polysialylate for strain K1. Alignment of the amino acid sequence of E. coli CMP-NeuAc synthetase with those from other bacterial species revealed that the conserved motifs were located in its N termini, whereas the C terminus appeared to be redundant. Based on this information, a series of deletions from the 3'-end of the CMPNeuAc synthetase coding region was constructed and expressed in E. coli. As a result, the catalytic domain required for CMP-NeuAc synthetase was found to be in the N-terminal half consisting of amino acids 1-229. Using the strategy of tertiary structure prediction based on the homologous search of the secondary structure, the C-terminal half was recognized as an alpha1-subunit of bovine brain platelet-activating factor acetylhydrolase isoform I. The biochemical analyses showed that the C-terminal half consisting of amino acids 228-418 exhibited platelet-activating factor acetylhydrolase activity. The enzyme properties and substrate specificity were similar to that of bovine brain alpha1-subunit. Although its physiological function is still unclear, it has been proposed that the alpha1-subunit-like domain of E. coli may be involved in the traversal of the blood-brain barrier.
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Affiliation(s)
- Guangchao Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, People's Republic of China
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15
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Bravo IG, Busto F, De Arriaga D, Ferrero MA, Rodríguez-Aparicio LB, Martínez-Blanco H, Reglero A. Application of a normalised plot to the study of uni-uni enzyme-inhibitor systems. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1571:183-9. [PMID: 12090932 DOI: 10.1016/s0304-4165(02)00214-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Normalisation of kinetic data is a useful tool in the study of complex enzyme systems. In the present paper, we have applied the premises of the normalised plot to the description of uni-uni enzyme inhibition. Guidelines to the design of the experiments and to data managing using the freeware program SIMFIT (http:\\www.simfit.man.ac.uk) are offered. The treatment has a lessened demand in experimental data while ensuring biological consistence of the results. Moreover, the results are obtained without resorting to secondary plots, and the election between rival mechanisms is statistically granted. Hyperbolic mixed-type inhibition is studied as a general model for enzyme-inhibitor/activator interaction, and equations describing classical cases of linear inhibition are also considered.
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Affiliation(s)
- Ignacio G Bravo
- Dipartmento Bioquímica y Biología Molecular, Universidad de León, Campus Vegazana, 24071, León, Spain
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Solana S, Reglero A A, Martínez-Blanco H, Revilla-Nuin B, Bravo IG, Rodríguez-Aparicio LB, Ferrero MA. N-Acetylneuraminic acid uptake in Pasteurella (Mannheimia) haemolytica A2 occurs by an inducible and specific transport system. FEBS Lett 2001; 509:41-6. [PMID: 11734203 DOI: 10.1016/s0014-5793(01)03130-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The N-acetylneuraminic acid (NeuAc) transport system of Pasteurella (Mannheimia) haemolytica A2 was studied when this bacterium was grown in both complex and chemically defined media. Kinetic measurements were carried out at 37 degrees C in 50 mM Tris-HCl buffer, pH 8.0, containing 50 microg/ml bovine serum albumin. Under these conditions, the uptake rate was linear for at least 3 min and the calculated K(m) for NeuAc was 0.1 microM. The transport rate was increased by the addition of several cations and was inhibited by sodium arsenite (95%), N,N'-dicyclohexyl-carbodiimide (50%), and 2,4-dinitrophenol (40%) at final concentration of 1 mM (each). These results support the notion that NeuAc uptake is an active sugar cation symporter. Study of specificities showed that glucosamine, mannose and mannosamine inhibited the transport of NeuAc in this bacterium. Analysis of expression revealed that the NeuAc transport system was induced by NeuAc and by the simultaneous presence of glucose and galactose in the growth medium.
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Affiliation(s)
- S Solana
- Departamento de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana, 24007, León, Spain
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Bravo IG, Busto F, De Arriaga D, Ferrero MA, Rodríguez-Aparicio LB, Martínez-Blanco H, Reglero A. A normalized plot as a novel and time-saving tool in complex enzyme kinetic analysis. Biochem J 2001; 358:573-83. [PMID: 11577687 PMCID: PMC1222113 DOI: 10.1042/bj3580573] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A new data treatment is described for designing kinetic experiments and analysing kinetic results for multi-substrate enzymes. Normalized velocities are plotted against normalized substrate concentrations. Data are grouped into n + 1 families across the range of substrate or product tested, n being the number of substrates plus products assayed. It has the following advantages over traditional methods: (1) it reduces to less than a half the amount of data necessary for a proper description of the system; (2) it introduces a self-consistency checking parameter that ensures the 'scientific reliability' of the mathematical output; (3) it eliminates the need for a prior knowledge of Vmax; (4) the normalization of data allows the use of robust and fuzzy methods suitable for managing really 'noisy' data; (5) it is appropriate for analysing complex systems, as the complete general equation is used, and the actual influence of effectors can be typified; (6) it is amenable to being implemented as a software that incorporates testing and electing among rival kinetic models.
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Affiliation(s)
- I G Bravo
- Departamento de Bioquímica y Biología Molecular, Universidad de León, Campus Vegazana, Spain
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