Biochemistry and Pharmacology - Research Publications

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Start date: 2013 × Author: Parker, Michael × Author: Doughty, Larissa × End date: 2019 ×

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    Bapineuzumab captures the N-terminus of the Alzheimer's disease amyloid-beta peptide in a helical conformation
    Miles, LA ; Crespi, GAN ; Doughty, L ; Parker, MW (NATURE PORTFOLIO, 2013-02-18)
    Bapineuzumab is a humanized antibody developed by Pfizer and Johnson & Johnson targeting the amyloid (Aβ) plaques that underlie Alzheimer's disease neuropathology. Here we report the crystal structure of a Fab-Aβ peptide complex that reveals Bapineuzumab surprisingly captures Aβ in a monomeric helical conformation at the N-terminus. Microscale thermophoresis suggests that the Fab binds soluble Aβ(1-40) with a K(D) of 89 (±9) nM. The structure explains the antibody's exquisite selectivity for particular Aβ species and why it cannot recognize N-terminally modified or truncated Aβ peptides.
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    Small Molecule Binding to Alzheimer Risk Factor CD33 Promotes Aβ Phagocytosis
    Miles, LA ; Hermans, SJ ; Crespi, GAN ; Gooi, JH ; Doughty, L ; Nero, TL ; Markulic, J ; Ebneth, A ; Wroblowski, B ; Oehlrich, D ; Trabanco, AA ; Rives, M-L ; Royaux, I ; Hancock, NC ; Parker, MW (CELL PRESS, 2019-09-27)
    Polymorphism in the microglial receptor CD33 gene has been linked to late-onset Alzheimer disease (AD), and reduced expression of the CD33 sialic acid-binding domain confers protection. Thus, CD33 inhibition might be an effective therapy against disease progression. Progress toward discovery of selective CD33 inhibitors has been hampered by the absence of an atomic resolution structure. We report here the crystal structures of CD33 alone and bound to a subtype-selective sialic acid mimetic called P22 and use them to identify key binding residues by site-directed mutagenesis and binding assays to reveal the molecular basis for its selectivity toward sialylated glycoproteins and glycolipids. We show that P22, when presented on microparticles, increases uptake of the toxic AD peptide, amyloid-β (Aβ), into microglial cells. Thus, the sialic acid-binding site on CD33 is a promising pharmacophore for developing therapeutics that promote clearance of the Aβ peptide that is thought to cause AD.
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    Potent hepatitis C inhibitors bind directly to NS5A and reduce its affinity for RNA
    Ascher, DB ; Wielens, J ; Nero, TL ; Doughty, L ; Morton, CJ ; Parker, MW (NATURE PORTFOLIO, 2014-04-23)
    Hepatitis C virus (HCV) infection affects more than 170 million people. The high genetic variability of HCV and the rapid development of drug-resistant strains are driving the urgent search for new direct-acting antiviral agents. A new class of agents has recently been developed that are believed to target the HCV protein NS5A although precisely where they interact and how they affect function is unknown. Here we describe an in vitro assay based on microscale thermophoresis and demonstrate that two clinically relevant inhibitors bind tightly to NS5A domain 1 and inhibit RNA binding. Conversely, RNA binding inhibits compound binding. The compounds bind more weakly to known resistance mutants L31V and Y93H. The compounds do not affect NS5A dimerisation. We propose that current NS5A inhibitors act by favouring a dimeric structure of NS5A that does not bind RNA.