Carbon-13 NMR investigation of the anomeric specificity of CMP-N-acetylneuraminic acid synthetase from Escherichia coli

Ambrose, Michael G.; Freese, Stephen; Reinhold, Mary S.; Warner, Thomas G.; Vann, Willie F.

doi:10.1021/bi00118a019

Cited by 25 publications

(25 citation statements)

References 26 publications

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“…6 and 8). The axial, O2 atom of NeuAc is directed at the ␣ phosphate of the biologically significant CDP conformer (conformation I) in accordance with the known specificity of CMPNeuAc synthetase (41). The NeuAc C2 carboxylate (a strong acid) is directed away from the cleft and forms a salt bridge with the Arg-165 guanidinium in the model.…”

Section: Fig 4 Cmp-neuac Synthetase Active Site In the Presence Andmentioning

confidence: 61%

Structure of a Sialic Acid-activating Synthetase, CMP-acylneuraminate Synthetase in the Presence and Absence of CDP

Mosimann

Gilbert²,

Dombroswki

et al. 2001

Journal of Biological Chemistry

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The x-ray crystallographic structure of selenomethionyl cytosine-5-monophosphate-acylneuraminate synthetase (CMP-NeuAc synthetase) from Neisseria meningitidis has been determined at 2.0-Å resolution using multiple-wavelength anomalous dispersion phasing, and a second structure, in the presence of the substrate analogue CDP, has been determined at 2.2-Å resolution by molecular replacement. This work identifies the active site residues for this class of enzyme for the first time. The detailed interactions between the enzyme and CDP within the mononucleotide-binding pocket are directly observed, and the acylneuraminate-binding pocket has also been identified. A model of acylneuraminate bound to CMP-NeuAc synthetase has been constructed and provides a structural basis for understanding the mechanism of production of "activated" sialic acids. Sialic acids are key saccharide components on the surface of mammalian cells and can be virulence factors in a variety of bacterial species (e.g. Neisseria, Haemophilus, group B streptococci, etc.). As such, the identification of the bacterial CMP-NeuAc synthetase active site can serve as a starting point for rational drug design strategies.Cytosine-5Ј-monophosphate-acylneuraminate synthetase (cytosine-5Ј-monophosphate-N-acetyl neuraminic acid synthetase, CMP-NeuAc synthetase) 1 catalyzes the penultimate step in the addition of sialic acids to the oligosaccharide component of glycoconjugates and is a required component of sialylation pathways. CMP-NeuAc synthetase-deficient mutants do not express sialylated glycoconjugates and can be complemented with functional CMP-NeuAc synthetase in both mammalian (1) and bacterial systems (2). Sialic acids participate in a myriad of signaling, recognition, and cell-cell adhesion phenomena in mammalian cells (3) and are overexpressed in some highly malignant tumors (4). Genetic disorders that lead to altered physiological levels of sialic acids have many consequences in humans and can be fatal (5). In bacterial systems, sialic acids are less common and frequently have roles as virulence factors (6). In Neisseria gonorrhoeae, sialylated glycoconjugates protect the organism from phagocytosis and increase serum resistance (7). In Haemophilus ducreyi the presence of 2-keto-3-deoxy-manno-octulosonate-containing glycoconjugates correlate with the organism's pathogenicity (8). Likewise, the sialylated capsule of Neisseria meningitidis, Escherichia coli K1, and group B streptococci are virulence factors (9-11). It has been suggested that bacterial species produce sialylated glycoconjugates to mimic the host and escape detection by the immune system (12). Clearly, the mechanism of production of sialic acid-containing glycoconjugates is of clinical interest. Although bacterial and eucaryotic CMPNeuAc synthetase enzymes share many catalytic properties, several important differences have been reported, including substrate specificity, tertiary structure, inhibitor sensitivity, and cellular localization (13). As a result, bacterial CMP-NeuAc synthetase en...

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Section: Fig 4 Cmp-neuac Synthetase Active Site In the Presence Andmentioning

confidence: 61%

Structure of a Sialic Acid-activating Synthetase, CMP-acylneuraminate Synthetase in the Presence and Absence of CDP

Mosimann

Gilbert²,

Dombroswki

et al. 2001

Journal of Biological Chemistry

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“…Both forms are interconverted by mutarotation as the ring opens to the straight-chain conformation followed by ring closure. The ␤ configuration of the sialic acid substrate is maintained when coupled (activated) with CTP by CMP-sialic acid synthetase, which transfers the anomeric oxygen of ␤-sialic acid to the ␣-phosphate of CTP (3). Chemical reactivity of the acceptor hydroxyl is relatively low; therefore, all carbohydrate donors must be activated by first being coupled to a trinucleotide phosphate with removal of one or two phosphates.…”

Section: Sialic Acid Structuresmentioning

confidence: 99%

Diversity of Microbial Sialic Acid Metabolism

Vimr

Kalivoda

Deszo

et al. 2004

Microbiol Mol Biol Rev

505

663

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Sialic acids are structurally unique nine-carbon keto sugars occupying the interface between the host and commensal or pathogenic microorganisms. An important function of host sialic acid is to regulate innate immunity, and microbes have evolved various strategies for subverting this process by decorating their surfaces with sialylated oligosaccharides that mimic those of the host. These subversive strategies include a de novo synthetic pathway and at least two truncated pathways that depend on scavenging host-derived intermediates. A fourth strategy involves modification of sialidases so that instead of transferring sialic acid to water (hydrolysis), a second active site is created for binding alternative acceptors. Sialic acids also are excellent sources of carbon, nitrogen, energy, and precursors of cell wall biosynthesis. The catabolic strategies for exploiting host sialic acids as nutritional sources are as diverse as the biosynthetic mechanisms, including examples of horizontal gene transfer and multiple transport systems. Finally, as compounds coating the surfaces of virtually every vertebrate cell, sialic acids provide information about the host environment that, at least in Escherichia coli, is interpreted by the global regulator encoded by nanR. In addition to regulating the catabolism of sialic acids through the nan operon, NanR controls at least two other operons of unknown function and appears to participate in the regulation of type 1 fimbrial phase variation. Sialic acid is, therefore, a host molecule to be copied (molecular mimicry), eaten (nutrition), and interpreted (cell signaling) by diverse metabolic machinery in all major groups of mammalian pathogens and commensals

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“…Biosynthesis of sialylated structures requires activation of the Sia monomer by transfer of the ␣-phosphate of CTP to the anomeric oxygen of Neu5Ac (35). Synthesis of CMP-Neu5Ac is catalyzed by a cytidyltransferase (CMP-Sia synthetase).…”

Section: N-acetylneuraminic Acid (Neu5ac)mentioning

confidence: 99%

NeuA Sialic Acid O-Acetylesterase Activity Modulates O-Acetylation of Capsular Polysaccharide in Group B Streptococcus

Lewis

Cao

Patel

et al. 2007

Journal of Biological Chemistry

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Carbon-13 NMR investigation of the anomeric specificity of CMP-N-acetylneuraminic acid synthetase from Escherichia coli

Cited by 25 publications

References 26 publications

Structure of a Sialic Acid-activating Synthetase, CMP-acylneuraminate Synthetase in the Presence and Absence of CDP

Structure of a Sialic Acid-activating Synthetase, CMP-acylneuraminate Synthetase in the Presence and Absence of CDP

Diversity of Microbial Sialic Acid Metabolism

NeuA Sialic Acid O-Acetylesterase Activity Modulates O-Acetylation of Capsular Polysaccharide in Group B Streptococcus

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