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Molecular Dynamics Analysis Of Apolipoprotein-D - Lipid Hydroperoxide Interactions: Mechanism For Selective Oxidation Of Met-93, Aaron J. Oakley, Surabhi Bhatia, Heath Ecroyd, Brett Garner

Heath Ecroyd

Background: Recent studies suggest reduction of radical-propagating fatty acid hydroperoxides to inert hydroxides by interaction with apolipoprotein-D (apoD) Met93 may represent an antioxidant function for apoD. The nature and structural consequences of this selective interaction are unknown. Methodology/Principal Findings: Herein we used molecular dynamics (MD) analysis to address these issues. Longtimescale simulations of apoD suggest lipid molecules are bound flexibly, with the molecules free to explore multiple conformations in a binding site at the entrance to the classical lipocalin ligand-binding pocket. Models of 5s- 12s- and 15s hydroperoxyeicosatetraenoic acids were created and the lipids found to wrap around Met93 thus …

Binding Of The Molecular Chaperone Alphab-Crystallin To Abeta Amyloid Fibrils Inhibits Fibril Elongation, Sarah L. Shammas, Christopher A. Waudby, Shuyu Wang, Alexander K. Buell, Tuomas P. Knowles, Heath W. Ecroyd, Mark E. Welland, John A. Carver, Christopher M. Dobson, Sarah Meehan

Heath Ecroyd

The molecular chaperone αB-crystallin is a small heat-shock protein that is upregulated in response to a multitude of stress stimuli, and is found colocalized with Aβ amyloid fibrils in the extracellular plaques that are characteristic of Alzheimer's disease. We investigated whether this archetypical small heat-shock protein has the ability to interact with Aβ fibrils in vitro. We find that αB-crystallin binds to wild-type Aβ42 fibrils with micromolar affinity, and also binds to fibrils formed from the E22G Arctic mutation of Aβ42. Immunoelectron microscopy confirms that binding occurs along the entire length and ends of the fibrils. Investigations into the effect …

Enhanced Molecular Chaperone Activity Of The Small Heat-Shock Protein Alphab-Cystallin Following Covalent Immobilization Onto A Solid-Phase Support, V Bellotti, Heath Ecroyd, J Carver, H J Griesser, B Thierry, J G Shapter, S S Griesser, S Giorgetti, M R Nussio, J A Gerrard, J Garvey

Heath Ecroyd

The well-characterized small heat-shock protein, alphaB-crystallin, acts as a molecular chaperone by interacting with unfolding proteins to prevent their aggregation and precipitation. Structural perturbation (e.g., partial unfolding) enhances the in vitro chaperone activity of alphaB-crystallin. Proteins often undergo structural perturbations at the surface of a synthetic material, which may alter their biological activity. This study investigated the activity of alphaB-crystallin when covalently bound to a support surface; alphaB-crystallin was immobilized onto a range of solid material surfaces, and its characteristics and chaperone activity were assessed. Immobilization was achieved via a plasma-deposited thin polymeric interlayer containing aldehyde surface groups and reductive …

Activity And Molecular Dynamics Relationship Within The Family Of Human Cholinesterase, Judith Peters, Marie Trovaslet, Marcus Trapp, Florian Nachon, Flynn Hill, Etienne Royer, Frank Gabel, Lambert Van Eijck, Patrick Masson, Moeava Tehei

Faculty of Science - Papers (Archive)

The temperature dependence of the dynamics of recombinant human acetylcholinesterase (hAChE) and plasma human butyrylcholinesterase (hBChE) is examined using elastic incoherent neutron scattering. These two enzymes belong to the same family and present 50% amino acid sequence identity. However, significantly higher flexibility and catalytic activity of hAChE when compared to the ones of hBChE are measured. At the same time, the average height of the potential barrier to the motions is increased in the hBChE, e.g. more thermal energy is needed to cross it in the latter case, which might be the origin of the increase in activation energy and …

Emulsion-Coaxial Electrospinning: Designing Novel Architectures For Sustained Release Of Highly Soluble Low Molecular Weight Drugs, Lucie Viry, Simon E. Moulton, Tony Romeo, Courtney Suhr, Damia Mawad, Mark Cook, Gordon G. Wallace

Faculty of Science - Papers (Archive)

In drug therapy, most therapeutic drugs are of low molecular weight and could freely diffuse in the biological milieu depending on the administration route applied. The main reason for the development of polymeric drug carriers is to obtain desired effects such as sustained therapy, local and controlled release, prolonged activity and reduction of side effects. Alternatively, polymeric carriers can be made bioerodible in order to be eliminated by natural ways after a certain time of therapy. Core-shell fibres from coaxial spinneret or emulsion electrospinning are good candidates for the development of such devices; however difficulties remain especially in controlling the …

Molecular Characterization Of A 21.4 Kilobase Antibiotic Resistance Plasmid From An Hemolytic Escherichia Coli O108:H-Human Clinical Isolate, Fay E. Dawes, Dieter M. Bulach, Alexander Kuzevski, Karl A. Bettelheim, Carola Venturini, Steven P. Djordjevic, Mark J. Walker

Faculty of Science - Papers (Archive)

This study characterizes the 21.4 kilobase plasmid pECTm80 isolated from Escherichia coli strain 80, an α hemolytic human clinical diarrhoeal isolate (serotype O108:H-). DNA sequence analysis of pECTm80 revealed it belonged to incompatibility group X1, and contained plasmid partition and toxin-antitoxin systems, an R6K-like triple origin (ori) replication system, genes required for replication regulation, insertion sequences IS1R, ISEc37 and a truncated transposase gene (Tn3-like ΔtnpA) of the Tn3 family, and carried a class 2 integron. The class 2 integron of pECTm80 contains an intact cassette array dfrA1-sat2, encoding resistance to trimethoprim and streptothricin, …

Activation Of The Damage-Associated Molecular Pattern Receptor P2x7 Induces Interleukin-1b Release From Canine Monocytes, Iman Jalilian, Michelle Peranec, Belinda L. Curtis, Aine Seavers, Mari Spildrejorde, Vanessa Sluyter, Ronald Sluyter

Faculty of Science - Papers (Archive)

P2X7, a damage-associated molecular pattern receptor and adenosine 5'-triphosphate (ATP)-gated cation channel, plays an important role in the activation of the NALP3 inflammasome and subsequent release of interleukin (IL)-1β from human monocytes; however its role in monocytes from other species including the dog remains poorly defined. This study investigated the role of P2X7 in canine monocytes, including its role in IL-1β release. A fixed-time flow cytometric assay demonstrated that activation of P2X7 by extracellular ATP induces the uptake of the organic cation, YO-PRO-1²⁺, into peripheral blood monocytes from various dog breeds, a process impaired by the specific P2X7 …

Molecular Characterization Of Escherichia Coli Strains That Cause Symptomatic And Asymptomatic Urinary Tract Infections, Sam Abraham, Toni A. Chapman, Ren Zhang, James Chin, Amanda N. Mabbett, Makrina Totsika, Mark A. Schembri

Faculty of Science - Papers (Archive)

The differences between Escherichia coli strains associated with symptomatic and asymptomatic urinary tract infections (UTIs) remain to be properly determined. Here we examined the prevalence of plasmid types and bacteriocins, as well as genetic relatedness, in a defined collection of E. coli strains that cause UTIs. Comparative analysis identified a subgroup of strains with a high number of virulence genes (VGs) and microcins M/H47. We also identified associations between microcin genes, VGs, and specific plasmid types.

Molecular Dynamics Analysis Of Apolipoprotein-D - Lipid Hydroperoxide Interactions: Mechanism For Selective Oxidation Of Met-93, Aaron J. Oakley, Surabhi Bhatia, Heath Ecroyd, Brett Garner

Faculty of Science - Papers (Archive)

Background: Recent studies suggest reduction of radical-propagating fatty acid hydroperoxides to inert hydroxides by interaction with apolipoprotein-D (apoD) Met93 may represent an antioxidant function for apoD. The nature and structural consequences of this selective interaction are unknown.

Methodology/Principal Findings: Herein we used molecular dynamics (MD) analysis to address these issues. Longtimescale simulations of apoD suggest lipid molecules are bound flexibly, with the molecules free to explore multiple conformations in a binding site at the entrance to the classical lipocalin ligand-binding pocket. Models of 5s- 12s- and 15s hydroperoxyeicosatetraenoic acids were created and the lipids found to wrap around Met93 thus …

Molecular Mechanisms Of K+ Selectivity In Na/K Pump, Haibo Yu, Ian Ratheal, Pablo Artigas, Benoit Roux

Faculty of Science - Papers (Archive)

The sodium–potassium (Na/K) pump plays an essential role in maintaining cell volume and secondary active transport of other solutes by establishing the Na⁺ and K⁺ concentration gradients across the plasma membrane of animal cells. The recently determined crystal structures of the Na/K pump to atomic resolution provide a new impetus to investigate molecular determinants governing the binding of Na⁺ and K⁺ ions and conformational transitions during the functional cycle. The pump cycle is generally described by the alternating access mechanism, in which the pump toggles between different conformational states, where ions can bind from either the …

Molecular Characterization Of Commensal Escherichia Coli Adapted To Different Compartments Of The Porcine Gastrointestinal Tract, Sam Abraham, David M. Gordon, James Chin, Huub J. M Brouwers, Peter Njuguna, Mitchell D. Groves, Ren Zhang, Toni A. Chapman

Faculty of Science - Papers (Archive)

The role of Escherichia coli as a pathogen has been the focus of considerable study, while much less is known about it as a commensal and how it adapts to and colonizes different environmental niches within the mammalian gut. In this study, we characterize Escherichia coli organisms (n=146) isolated from different regions of the intestinal tracts of eight pigs (dueodenum, ileum, colon, and feces). The isolates were typed using the method of random amplified polymorphic DNA (RAPD) and screened for the presence of bacteriocin genes and plasmid replicon types. Molecular analysis of variance using the RAPD data showed that E. …

Beyond Barcoding: A Mitochondrial Genomics Approach To Molecular Phylogenetics And Diagnostics Of Blowflies (Diptera: Calliphoridae), Leigh Nelson, Christine L. Lambkin, Philip Batterham, James F. Wallman, Mark P. Dowton, Michael F. Whiting, David K. Yeates, Stephen L. Cameron

Faculty of Science - Papers (Archive)

Members of the Calliphoridae (blowflies) are significant for medical and veterinary management, due to the ability of some species to consume living flesh as larvae, and for forensic investigations due to the ability of others to develop in corpses. Due to the difficulty of accurately identifying larval blowflies to species there is a need for DNA-based diagnostics for this family, however the widely used DNA-barcoding marker, cox1, has been shown to fail for several groups within this family. Additionally, many phylogenetic relationships within the Calliphoridae are still unresolved, particularly deeper level relationships. Sequencing whole mt genomes has been demonstrated both …