Browsing by Author "Moir, M"

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    Advancements in the provision of deuterated lipids for neutron applications from the National Deuteration Facility
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Yepuri, NR; Moir, M; Krause-Heuer, AM; Klenner, MA; Darwish, TA
    Molecular deuteration significantly increases the options for structure-function investigations using neutron scattering and diffraction techniques. Chemical deuteration activities, where catalysed 1H/2H exchange is followed by custom chemical synthesis, have led to diverse neutron scattering and reflectometry studies previously hampered by the lack of appropriate scattering contrast in multi-component samples. Deuteration of phospholipids is a common practice to elucidate membrane structure, dynamics and function, by providing selective visualisation in neutron scattering. Although analogous deuterium? (2H) and hydrogen? containing (1H) molecules have similar physicochemical properties, these isotopes of hydrogen result in vastly different for neutron scattering signals. Over the past few years the National Deuteration Facility (ANSTO) has increased its synthetic capability to produce complex deuterated molecules including lipids and phospholipids. Such synthetically challenging molecules are perdeuterated phytantriol1, tail deuterated POPC, and perdeuterated POPC.2 Phytantriol is an interfacially-active lipid that is chemically robust, non-digestible and forms particles with internal bicontinuous cubic phase structures (cubosomes) when dispersed with non-ionic surfactants at physiological temperatures. The tail-deuterated POPC, perdeuterated POPC and tail-deuterated GMO isotopologues would also provide suitable contrast for many neutron experiments and so these have been also our synthetic targets. Recently neutron reflection was employed to investigate the impact of phospholipid saturation (POPC-d64) and presence of cholesterol in cell model membranes on LDL and HDL lipid exchange and removal processes.3 Neutron reflection data that distinguish the effect of phospholipid acyl chain saturation and the presence of cholesterol on the ability of lipoproteins to exchange lipids to/from model membrane will be presented.
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    ANSTO’s National Deuteration Facility: recent advancements and an overview on molecular deuteration capabilities for neutron applications
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Wilde, KL; Cagnes, MP; Duff, AP; Klenner, MA; Krause-Heuer, AM; Moir, M; Rekas, A; Russell, RA; Yepuri, NR; Darwish, TA
    The National Deuteration Facility (NDF) at the Australian Nuclear Science and Technology Organisation (ANSTO) provides deuteration through both biological and chemical techniques for a diversity of molecules and applications and is the only facility of its type in the Southern Hemisphere with the specialised expertise and infrastructure for both biological and chemical molecular deuteration. Molecular deuteration of organic compounds and biomolecules significantly increases the options in complex structure function investigations using neutron scattering and reflectometry, nuclear magnetic resonance (NMR), mass spectrometry (MS) and other techniques. Deuteration (substitution of the naturally occurring hydrogen stable isotope deuterium (2H or D) for 1H (or H)) can provide contrast and improved resolution to assist investigations into the relationship between molecular structure and function of molecules of both biological and synthetic origin. By developing a suite of capabilities in both in vivo deuteration of biomolecules and chemical deuteration of small organic molecules, the NDF provides access to a broad range of deuterated molecules for research and industry. Variably deuterated proteins can be produced via recombinant expression in Escherichia coli and other microbial systems utilised to produce deuterated cellulose and cholesterol. By tailoring deuteration approaches with the ongoing development of chemical deuteration protocols for a broader range of molecular classes than available commercially, the NDF has increased the range of systems that can be investigated using deuterated molecules. Lipids, phospholipids (including head or tail or head/tail deuterated mono-unsaturated lipids such as POPC and DOPC), heterocyclics, aromatics, surfactants, ionic liquids, saturated and unsaturated fatty acids, sugars and match-out detergents have been deuterated. Common neutron applications include partially deuterated proteins for SANS experiments investigating multiprotein systems, neutron crystallography of perdeuterated proteins, neutron reflectometry of lipid bilayers systems and SANS using saturated lipid vesicles, or detergents amongst others. An overview and update on the NDF will be provided which will include details on the NDF User Program (e.g. information on the available modes of access), recent advancements in custom deuterated molecules available and brief highlights of deuterated molecule utilisation for neutron experiments at ANSTO’s Australian Centre for Neutron Scattering (ACNS). © 2020 The Authors.
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    Deuterated phospholipids to study the structure, function and dynamics of membrane proteins using neutron scattering
    (Australian Nuclear Science and Technology Organisation, 2021-11-26) Yepuri, NR; Moir, M; Krause-Heuer, AM; Darwish, TA
    Contrast matching and contrast variation in neutron scattering provide unparalleled power for understanding the structure, function, and dynamics of a selected component in a multicomponent system. A sophisticated contrast study often requires the availability of deuterated molecules in which deuterium atoms are introduced in a predictable and controlled fashion to replace protons. This can be achieved by direct deuteration of precursors followed by custom chemical synthesis, for which expertise and capabilities have been developed at facility (NDF), ANSTO. It this paper we will discuss recent high impact research output using deuterated phospholipids produced by NDF/ANSTO. We will describe the synthesis and applications of selectively or perdeuterated unsaturated phospholipids to contrast match out the whole lipid bilayer or nano disks within a multicomponent system. Further, we also describe their role in investigations related to membrane lipoproteins (ApoE) exchange in relation to lipid unsaturation,[1] effect of membrane composition,[2] and conformational analysis Mg+2 channel by neutron scattering techniques.[2, 3]
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    Deuteration for biological SANS: case studies, success and challenges in chemistry and biology
    (Elsevier, 2022-11) Duff, AP; Cagnes, MP; Darwish, TA; Krause-Heuer, AM; Moir, M; Recsei, C; Rekas, A; Russell, RA; Wilde, KL; Yepuri, NR
    Small angle neutron scattering is a powerful complementary technique in structural biology. It generally requires, or benefits from, deuteration to achieve its unique potentials. Molecular deuteration has become a mature expertise, with deuteration facilities located worldwide to support access to the technique for a wide breadth of structural biology and life sciences. The sorts of problems well answered by small angle scattering and deuteration involve large (> 10 Å) scale flexible movements, and this approach is best used where high-resolution methods (crystallography, NMR, cryo-EM) leave questions unanswered. This chapter introduces deuteration, reviewing biological deuteration of proteins, lipids and sterols, and then steps through the ever-expanding range of deuterated molecules being produced by chemical synthesis and enabling sophisticated experiments using physiologically relevant lipids. Case studies of recent successful use of deuteration may provide illustrative examples for strategies for future experiments. We discuss issues of nomenclature for synthesised molecules of novel labeling and make recommendations for their naming. We reflect on our experiences, with cost associated with achieving an arbitrary deuteration level, and on the benefits of experimental co-design by user scientist, deuteration scientist, and neutron scattering scientist working together. Although methods for biological and chemical deuteration are published in the public domain, we recommend that the best method to deuterate is to engage with a deuteration facility. © 2022 Elsevier
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    High-density lipoprotein function is modulated by the SARS-CoV-2 spike protein in a lipid-type dependent manner
    (Elsevier B. V., 2023-09) Correa, YB; Del Giuduce, R; Waldie, S; Thépaut, M; Gerelli, Y; Moulin, M; Delauney, C; Fieschi, F; Haertlein, M; Le Brun, AP; Forsyth, VT; Moir, M; Russell, RA; Darwish, TA; Brinck, J; Wodaje, T; Jansen, M; Martín, C; Roosen-Runge, F; Cárdenas, M; Micciulla, S; Pichler, H
    There is a close relationship between the SARS-CoV-2 virus and lipoproteins, in particular high-density lipoprotein (HDL). The severity of the coronavirus disease 2019 (COVID-19) is inversely correlated with HDL plasma levels. It is known that the SARS-CoV-2 spike (S) protein binds the HDL particle, probably depleting it of lipids and altering HDL function. Based on neutron reflectometry (NR) and the ability of HDL to efflux cholesterol from macrophages, we confirm these observations and further identify the preference of the S protein for specific lipids and the consequent effects on HDL function on lipid exchange ability. Moreover, the effect of the S protein on HDL function differs depending on the individuals lipid serum profile. Contrasting trends were observed for individuals presenting low triglycerides/high cholesterol serum levels (LTHC) compared to high triglycerides/high cholesterol (HTHC) or low triglycerides/low cholesterol serum levels (LTLC). Collectively, these results suggest that the S protein interacts with the HDL particle and, depending on the lipid profile of the infected individual, it impairs its function during COVID-19 infection, causing an imbalance in lipid metabolism. © Crown Copyright 2023. Published by Elsevier Inc. Open Access - CC BY licence 4.0.
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    pH-dependent interactions of coacervate-forming histidine-rich peptide with model lipid membranes
    (Frontiers Media, 2024-01-19) Gudler, S; Ferreira, FV; Ting, JSM; Domene, C; Maricar, S; Le Brun, AP; Yepuri, NR; Moir, M; Russell, RA; Darwish, TA; Miserez, A; Cárdenas, M
    Peptide-based liquid droplets (coacervates) produced by spontaneous liquid-liquid phase separation (LLPS), have emerged as a promising class of drug delivery systems due to their high entrapping efficiency and the simplicity of their formulation. However, the detailed mechanisms governing their interaction with cell membranes and cellular uptake remain poorly understood. In this study, we investigated the interactions of peptide coacervates composed of HBpep—peptide derived from the histidine-rich beak proteins (HBPs) of the Humboldt squid—with model cellular membranes in the form of supported lipid bilayers (SLBs). We employed quartz crystal microbalance with dissipation monitoring (QCM-D), neutron reflectometry (NR) and atomistic molecular dynamics (MD) simulations to reveal the nature of these interactions in the absence of fluorescent labels or tags. HBpep forms small oligomers at pH 6 whereas it forms µm-sized coacervates at physiological pH. Our findings reveal that both HBpep oligomers and HBpep-coacervates adsorb onto SLBs at pH 6 and 7.4, respectively. At pH 6, when the peptide carries a net positive charge, HBpep oligomers insert into the SLB, facilitated by the peptide’s interactions with the charged lipids and cholesterol. Importantly, however, HBpep coacervate adsorption at physiological pH, when it is largely uncharged, is fully reversible, suggesting no significant lipid bilayer rearrangement. HBpep coacervates, previously identified as efficient drug delivery vehicles, do not interact with the lipid membrane in the same manner as traditional cationic drug delivery systems or cell-penetrating peptides. Based on our findings, HBpep coacervates at physiological pH cannot cross the cell membrane by a simple passive mechanism and are thus likely to adopt a non-canonical cell entry pathway. ©2024 Gudlur, Ferreira, Ting, Domene, Maricar, Le Brun, Yepuri, Moir, Russell, Darwish, Miserez and Cárdenas. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).
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    Synthesis of perdeuterated linoleic acid-d31 and chain deuterated 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine-d62
    (John Wiley & Sons, 2022-08-08) Moir, M; Yepuri, NR; Marshall, DL; Blanksby, SJ; Darwish, TA
    Herein, we report a gram-scale synthesis of perdeuterated linoleic acid-d31. The starting materials for the synthesis are two saturated fatty acids, azelaic acid-d14 and pentanoic acid-d9, which can be obtained by metal catalysed hydrothermal hydrogen-deuterium exchange. The synthesis utilises the fatty acids directly via decarboxylative coupling. Copper catalysed coupling of a terminal alkyne intermediate with a propargyl bromide derivative affords a skipped diyne, which can be reduced using P-2 nickel to obtain the desired cis,cis-diene geometry. The subsequent synthesis of the tail-deuterated phospholipid, 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine-d62 (PLPC-d62) is also described. Optimised reaction conditions were developed to access this phospholipid and its regioisomeric purity was characterised by two complementary mass spectrometry techniques. © 2022 The Authors - CC- BY Licence