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Ian A Wilson

Publications and source records attributed to Ian A Wilson.

At least 55 records · Page 3Linked to original sources
PubMed2005

Glycan microarray analysis of the hemagglutinins from modern and pandemic influenza viruses reveals different receptor specificities.

Influenza A virus specificity for the host is mediated by the viral surface glycoprotein hemagglutinin (HA), which binds to receptors containing glycans with terminal sialic acids. Avian viruses preferentially bind to alpha2-3-linked sialic acids on receptors of intestinal epithelial cells, whereas human viruses are specific for the alpha2-6 linkage on epithelial cells of the lungs and upper respiratory tract. To define the receptor preferences of a number of human and avian H1 and H3 viruses, including the 1918 H1N1 pandemic strains, their hemagglutinins were analyzed using a recently described glycan array. The array, which contains 200 carbohydrates and glycoproteins, not only revealed clear differentiation of receptor preferences for alpha2-3 and/or alpha2-6 sialic acid linkage, but could also detect fine differences in HA specificity, such as preferences for fucosylation, sulfation and sialylation at positions 2 (Gal) and 3 (GlcNAc, GalNAc) of the terminal trisaccharide. For the two 1918 HA variants, the South Carolina (SC) HA (with Asp190, Asp225) bound exclusively alpha2-6 receptors, while the New York (NY) variant, which differed only by one residue (Gly225), had mixed alpha2-6/alpha2-3 specificity, especially for sulfated oligosaccharides. Only one mutation of the NY variant (Asp190Glu) was sufficient to revert the HA receptor preference to that of classical avian strains. Thus, the species barrier, as defined by the receptor specificity preferences of 1918 human viruses compared to likely avian virus progenitors, can be circumvented by changes at only two positions in the HA receptor binding site. The glycan array thus provides highly detailed profiles of influenza receptor specificity that can be used to map the evolution of new human pathogenic strains, such as the H5N1 avian influenza.

Amino Acid Sequence↗
PubMed2005

Structure of a V3-containing HIV-1 gp120 core.

The third variable region (V3) of the HIV-1 gp120 envelope glycoprotein is immunodominant and contains features essential for coreceptor binding. We determined the structure of V3 in the context of an HIV-1 gp120 core complexed to the CD4 receptor and to the X5 antibody at 3.5 angstrom resolution. Binding of gp120 to cell-surface CD4 would position V3 so that its coreceptor-binding tip protrudes 30 angstroms from the core toward the target cell membrane. The extended nature and antibody accessibility of V3 explain its immunodominance. Together, the results provide a structural rationale for the role of V3 in HIV entry and neutralization.

Amino Acid Sequence↗
PubMed2005

Towards miniaturization of a structural genomics pipeline using micro-expression and microcoil NMR.

In structural genomics centers, nuclear magnetic resonance (NMR) screening is in increasing use as a tool to identify folded proteins that are promising targets for three-dimensional structure determination by X-ray crystallography or NMR spectroscopy. The use of 1D 1H NMR spectra or 2D [1H,15N]-correlation spectroscopy (COSY) typically requires milligram quantities of unlabeled or isotope-labeled protein, respectively. Here, we outline ways towards miniaturization of a structural genomics pipeline with NMR screening for folded globular proteins, using a high-density micro-fermentation device and a microcoil NMR probe. The proteins are micro-expressed in unlabeled or isotope-labeled media, purified, and then subjected to 1D 1H NMR and/or 2D [1H,15N]-COSY screening. To demonstrate that the miniaturization is functioning effectively, we processed nine mouse homologue protein targets and compared the results with those from the "macro-scale" Joint Center of Structural Genomics (JCSG) high-throughput pipeline. The results from the two pipelines were comparable, illustrating that the data were not compromised in the miniaturized approach.

Gene Expression Regulation↗
PubMed2005

Antibody vs. HIV in a clash of evolutionary titans.

HIV has evolved many strategies to avoid neutralizing antibody responses, particularly to conserved regions on the external glycoprotein spikes of the virus. Nevertheless, a small number of antibodies have been evolved by the human immune system to recognize conserved parts of the glycoproteins, and therefore, have broadly neutralizing cross-strain activities. These antibodies constitute important tools in the quest to design immunogens that can elicit broadly neutralizing antibodies in humans and hence contribute to an effective HIV vaccine. Crystallographic analyses of the antibodies, in many cases in an antigen-complexed form, have revealed novel and, in some instances, remarkable structural adaptations to attain virus recognition. Antibodies, like HIV, can evolve relatively rapidly through mutation and selection. It seems that the structures of these broadly neutralizing antibodies bear witness to a heroic struggle between two titans of rapid evolution.

AIDS Vaccines↗
PubMed2005

Crystal structure of viral macrophage inflammatory protein I encoded by Kaposi's sarcoma-associated herpesvirus at 1.7A.

Viral macrophage inflammatory protein I (vMIP-I) is a chemokine encoded by the Kaposi's sarcoma-associated herpesvirus (KSHV) that selectively activates the CC chemokine receptor 8 (CCR8), for which the endogenous ligand is CCL1. The crystal structure of vMIP-I was determined at 1.7A for comparison with other chemokines, especially those that bind CCR8, such as vMIP-II from KSHV, a CCR8 antagonist and the closest homolog (40% identical). vMIP-I has a typical chemokine fold consisting of an extended N-terminal loop, followed by a three-stranded antiparallel beta-sheet and a C-terminal alpha-helix. The four molecules in the asymmetric unit comprise two MIP-1beta-like dimers. Electrostatic surface representations of CCR8-binding chemokines reveal only minor areas of correlating surface potential, which must be reconciled with promiscuity in receptor and glycosaminoglycan (GAG) binding. In addition, the biological relevance of chemokine oligomerization is examined by comparing the oligomeric states of all chemokine structures deposited to date in the RCSB PDB.

Amino Acid Sequence↗
PubMed2005

NMR structure of the conserved hypothetical protein TM0487 from Thermotoga maritima: implications for 216 homologous DUF59 proteins.

The NMR structure of the conserved hypothetical protein TM0487 from Thermotoga maritima represents an alpha/beta-topology formed by the regular secondary structures alpha1-beta1-beta2-alpha2-beta3-beta4-alpha3- beta5-3(10)-alpha4, with a small anti-parallel beta-sheet of beta-strands 1 and 2, and a mixed parallel/anti-parallel beta-sheet of beta-strands 3-5. Similar folds have previously been observed in other proteins, with amino acid sequence identity as low as 3% and a variety of different functions. There are also 216 sequence homologs of TM0487, which all have the signature sequence of domains of unknown function 59 (DUF59), for which no three-dimensional structures have as yet been reported. The TM0487 structure thus presents a platform for homology modeling of this large group of DUF59 proteins. Conserved among most of the DUF59s are 13 hydrophobic residues, which are clustered in the core of TM0487. A putative active site of TM0487 consisting of residues D20, E22, L23, T51, T52, and C55 is conserved in 98 of the 216 DUF59 sequences. Asp20 is buried within the proposed active site without any compensating positive charge, which suggests that its pK(a) value may be perturbed. Furthermore, the DUF59 family includes ORFs that are part of a conserved chromosomal group of proteins predicted to be involved in Fe-S cluster metabolism.

Amino Acid Sequence↗
PubMed2005

Dissection of the carbohydrate specificity of the broadly neutralizing anti-HIV-1 antibody 2G12.

Human antibody 2G12 neutralizes a broad range of HIV-1 isolates. Hence, molecular characterization of its epitope, which corresponds to a conserved cluster of oligomannoses on the viral envelope glycoprotein gp120, is a high priority in HIV vaccine design. A prior crystal structure of 2G12 in complex with Man(9)GlcNAc(2) highlighted the central importance of the D1 arm in antibody binding. To characterize the specificity of 2G12 more precisely, we performed solution-phase ELISA, carbohydrate microarray analysis, and cocrystallized Fab 2G12 with four different oligomannose derivatives (Man(4), Man(5), Man(7), and Man(8)) that compete with gp120 for binding to 2G12. Our combined studies reveal that 2G12 is capable of binding both the D1 and D3 arms of the Man(9)GlcNAc(2) moiety, which would provide more flexibility to make the required multivalent interactions between the antibody and the gp120 oligomannose cluster than thought previously. These results have important consequences for the design of immunogens to elicit 2G12-like neutralizing antibodies as a component of an HIV vaccine.

AIDS Vaccines↗
PubMed2005

Crystal structure of mouse CD1d bound to the self ligand phosphatidylcholine: a molecular basis for NKT cell activation.

NKT cells are immunoregulatory lymphocytes whose activation is triggered by the recognition of lipid Ags in the context of the CD1d molecules by the TCR. In this study we present the crystal structure to 2.8 A of mouse CD1d bound to phosphatidylcholine. The interactions between the ligand acyl chains and the CD1d molecule define the structural and chemical requirements for the binding of lipid Ags to CD1d. The orientation of the polar headgroup toward the C terminus of the alpha1 helix provides a rationale for the structural basis for the observed Valpha chain bias in invariant NKT cells. The contribution of the ligand to the protein surface suggests a likely mode of recognition of lipid Ags by the NKT cell TCR.

Animals↗
PubMed2005

Structure and function of a potent agonist for the semi-invariant natural killer T cell receptor.

Natural killer T cells express a conserved, semi-invariant alphabeta T cell receptor that has specificity for self glycosphingolipids and microbial cell wall alpha-glycuronosylceramide antigens presented by CD1d molecules. Here we report the crystal structure of CD1d in complex with a short-chain synthetic variant of alpha-galactosylceramide at a resolution of 2.2 A. This structure elucidates the basis for the high specificity of these microbial ligands and explains the restriction of the alpha-linkage as a unique pathogen-specific pattern-recognition motif. Comparison of the binding of altered lipid ligands to CD1d and T cell receptors suggested that the differential T helper type 1-like and T helper type 2-like properties of natural killer T cells may originate largely from differences in their 'loading' in different cell types and hence in their tissue distribution in vivo.

Amino Acid Motifs↗
PubMed2005

Crystal structure of human toll-like receptor 3 (TLR3) ectodomain.

Toll-like receptors (TLRs) play key roles in activating immune responses during infection. The human TLR3 ectodomain structure at 2.1 angstroms reveals a large horseshoe-shaped solenoid assembled from 23 leucine-rich repeats (LRRs). Asparagines conserved in the 24-residue LRR motif contribute extensive hydrogen-bonding networks for solenoid stabilization. TLR3 is largely masked by carbohydrate, but one face is glycosylation-free, which suggests its potential role in ligand binding and oligomerization. Highly conserved surface residues and a TLR3-specific LRR insertion form a homodimer interface in the crystal, whereas two patches of positively charged residues and a second insertion would provide an appropriate binding site for double-stranded RNA.

Amino Acid Motifs↗
PubMed2005

Synthesis and biological evaluation of N-[4-[5-(2,4-diamino-6-oxo-1,6-dihydropyrimidin-5-yl)-2-(2,2,2-trifluoroacetyl)pentyl]benzoyl]-L-glutamic acid as a potential inhibitor of GAR Tfase and the de novo purine biosynthetic pathway.

The synthesis and evaluation of N-[4-[5-(2,4-diamino-6-oxo-1,6-dihydropyrimidin-5-yl)-2-(2,2,2-trifluoroacetyl)pentyl]benzoyl]-L-glutamic acid (2) as an inhibitor of glycinamide ribonucleotide transformylase (GAR Tfase) and aminoimidazole carboxamide ribonucleotide transformylase (AICAR Tfase) are reported. The inhibitor 2 was prepared in a convergent synthesis involving C-alkylation of methyl 4-(4,4,4-trifluoro-3-dimethylhydrazonobutyl)benzoate with 1-chloro-3-iodopropane followed by construction of the pyrimidinone ring. Compound 2 was found to be an effective inhibitor of recombinant human GAR Tfase (K(i) = 0.50 microM), whereas it was inactive (K(i) > 100 microM) against E. coli GAR Tfase as well as recombinant human AICAR Tfase. Compound 2 exhibited modest, purine-sensitive growth inhibitory activity against the CCRF-CEM cell line (IC50 = 6.0 microM).

Antineoplastic Agents↗
PubMed2005

Synthesis and biological evaluation of alpha- and gamma-carboxamide derivatives of 10-CF3CO-DDACTHF.

Structurally-related, but non-polyglutamylatable, derivatives of 10-CF3CO-DDACTHF (1), which incorporate L-glutamine (2) and L-isoglutamine (3) in place of L-glutamate, were prepared and evaluated as inhibitors of recombinant human (rh) GAR Tfase. While the L-glutamate alpha-carboxamide derivative 3 was much less effective as a rhGAR Tfase inhibitor (K(i) = 4.8 microM) and inactive in cellular functional assays, the gamma-carboxamide derivative 2 was found to be a potent and selective rhGAR Tfase inhibitor (K(i) = 0.056 microM) being only 4-fold less potent than 1 (K(i) = 0.015 microM). Moreover, 2 was effective in cellular functional assays exhibiting purine sensitive cytotoxic activity (IC50 = 300 nM, CCRF-CEM) only 20-fold less potent than 1 (IC50 = 16 nM), consistent with inhibition of de novo purine biosynthesis via selective inhibition of GAR Tfase. Like 1, 2 is transported into the cell by the reduced folate carrier. Unlike 1, the functional activity of 2 is not dependent upon FPGS polyglutamylation.

Amides↗