Structural insight into mammalian sialyltransferases

Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.
Nature Structural & Molecular Biology (Impact Factor: 13.31). 10/2009; 16(11):1186-8. DOI: 10.1038/nsmb.1685
Source: PubMed


Mammalian cell surfaces are modified by complex arrays of glycoproteins, glycolipids and polysaccharides, many of which terminate in sialic acid and have central roles in essential processes including cell recognition, adhesion and immunogenicity. Sialylation of glycoconjugates is performed by a set of sequence-related enzymes known as sialyltransferases (STs). Here we present the crystal structure of a mammalian ST, porcine ST3Gal-I, providing a structural basis for understanding the mechanism and specificity of these enzymes and for the design of selective inhibitors.

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Available from: Francesco V Rao
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    • "Residue N-173 shared the highest MI value with Y-303, both were located in the enzyme active site. N-173 was near donor substrate and participated in phosphate group stabilization, as described previously (Rao et al. 2009). The amino acid residue D-216 belonged to the b family motif and it has been reported to "
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    ABSTRACT: Sialyltransferases are responsible for the synthesis of a diverse range of sialoglycoconjugates predicted to be pivotal to deuterostomes' evolution. In the present work, we reconstructed the evolutionary history of the metazoan α2,3-sialyltransferases family (ST3Gal), a subset of sialyltransferases encompassing six subfamilies (ST3Gal I to ST3Gal VI) functionally characterized in mammals. Exploration of genomic and EST databases and search of conserved sialylmotifs led to the identification of a large data set of st3gal-related gene sequences. Molecular phylogeny and large scale sequence similarity network analysis identified four new vertebrate subfamilies called ST3Gal III-r, ST3Gal VII, ST3Gal VIII and ST3Gal IX. To address the issue of the origin and evolutionary relationships of the st3gal-related genes, we performed comparative syntenic mapping of st3gal gene loci combined to ancestral genome reconstruction. The ten vertebrate ST3Gal subfamilies originated from genome duplication events at the base of vertebrates and are organized in three distinct and ancient groups of genes predating the early deuterostomes. Inferring st3gal gene family history identified also several lineage-specific gene losses, the significance of which was explored in a functional context. Towards this aim, spatio-temporal distribution of st3gal genes was analyzed in zebrafish and bovine tissues. In addition, molecular evolutionary analyses using specificity determining position and co-evolved amino acid predictions led to the identification of amino acid residues with potential implication in functional divergence of vertebrate ST3Gal. We propose a detailed scenario of the evolutionary relationships of st3gal genes coupled to a conceptual framework of the evolution of ST3Gal functions. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
    Full-text · Article · Dec 2014 · Molecular Biology and Evolution
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    • "Based on their protein sequence similarity, all mammalian sialyltransferases are grouped into CAZy GT29 family. The crystal structures of two members of this mammalian sialyltransferase family, including porcine ST3Gal I [11] and rat ST6Gal I [12], have been reported. Among bacterial sialyltransferases, the structures of a multifunctional C. jejuni a2–3/8-sialyltransferase Cst-II [13] and C. jejuni a2–3-sialyltransferase Cst-I [14] belonging to CAZy GT42 family and Neisseria meningitidis lipopolysaccharide "
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    ABSTRACT: Sialyltransferase structures fall into either GT-A or GT-B glycosyltransferase fold. Some sialyltransferases from the Photobacterium genus have been shown to contain an additional N-terminal immunoglobulin (Ig)-like domain. Photobacterium damselae α2-6-sialyltransferase has been used efficiently in enzymatic and chemoenzymatic synthesis of α2-6-linked sialosides. Here we report three crystal structures of this enzyme. Two structures with and without a donor substrate analog CMP-3F(a)Neu5Ac contain an immunoglobulin (Ig)-like domain and adopt the GT-B sialyltransferase fold. The binary structure reveals a non-productive pre-Michaelis complex, which are caused by crystal lattice contacts that prevent the large conformational changes. The third structure lacks the Ig-domain. Comparison of the three structures reveals small inherent flexibility between the two Rossmann-like domains of the GT-B fold. Copyright © 2014. Published by Elsevier B.V.
    Full-text · Article · Nov 2014 · FEBS Letters
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    • "The inverting reaction of glycosyltransferases follows a S N 2-like mechanism (Lairson et al. 2008) and involves the formation of an oxocarbenium-like transition state with the concomitant departure of the nucleotide leaving group. In Cst-I and Cst-II, two conserved tyrosine residues [Y171 and Y177 in Cst-I (Chiu et al. 2007), Y156 and Y162 in Cst-II (Chiu et al. 2004)] are involved in the departure of the CMP group of CMP-Neu5Ac, while in GT29, GT52, and GT80 STs, a conserved histidine residue [H302 in pST3GalI (Rao et al. 2009), H280 in NST (Lin et al. 2011), and H311 in Δ24PmST1 (Ni et al. 2007)] is involved in stabilizing the phosphate of the departing CMP. "
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    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.
    Full-text · Article · Apr 2012 · Applied Microbiology and Biotechnology
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