Biology subjects

Mycroft-West, C.

Publications and source records attributed to Mycroft-West, C..

5 recordsLinked to original sources

bioRxiv2020

SARS-CoV-2 Spike S1 Receptor Binding Domain undergoes Conformational Change upon Interaction with Low Molecular Weight Heparins.

The dependence of the host on the interaction of hundreds of extracellular proteins with the cell surface glycosaminoglycan heparan sulphate (HS) for the regulation of homeostasis is exploited by many microbial pathogens as a means of adherence and invasion. The closely related polysaccharide heparin, the widely used anticoagulant drug, which is structurally similar to HS and is a common experimental proxy, can be expected to mimic the properties of HS. Heparin prevents infection by a range of viruses when added exogenously, including S-associated coronavirus strain HSR1 and inhibits cellular invasion by SARS-CoV-2. We have previously demonstrated that unfractionated heparin binds to the Spike (S1) protein receptor binding domain, induces a conformational change and have reported the structural features of heparin on which this interaction depends. Furthermore, we have demonstrated that enoxaparin, a low molecular weight clinical anticoagulant, also binds the S1 RBD protein and induces conformational change. Here we expand upon these studies, to a wide range of low molecular weight heparins and demonstrate that they induce a variety of conformational changes in the SARS-CoV-2 RBD. These findings may have further implications for the rapid development of a first-line therapeutic by repurposing low molecular weight heparins, as well as for next-generation, tailor-made, GAG-based antiviral agents, against SARS-CoV-2 and other members of the Coronaviridae.

biochemistry↗

bioRxiv2020

Glycosaminoglycans induce conformational change in the SARS-CoV-2 Spike S1 Receptor Binding Domain.

The glycosaminoglycan (GAG) class of polysaccharides are utilised by a plethora of microbial pathogens as receptors for adherence and invasion. The GAG heparin prevents infection by a range of viruses when added exogenously, including the S-associated coronavirus strain HSR1 and more recently we have demonstrated that heparin can block cellular invasion by SARS-CoV-2. Heparin has found widespread clinical use as anticoagulant drug and this molecule is routinely used as a proxy for the GAG, heparan sulphate (HS), a structural analogue located on the cell surface, which is a known receptor for viral invasion. Previous work has demonstrated that unfractionated heparin and low molecular weight heparins binds to the Spike (S1) protein receptor binding domain, inducing distinct conformational change and we have further explored the structural features of heparin with regard to these interactions. In this article, previous research is expanded to now include a broader range of GAG family members, including heparan sulphate. This research demonstrates that GAGs, other than those of heparin (or its derivatives), can also interact with the SARS-CoV-2 Spike S1 receptor binding domain and induce distinct conformational changes within this region. These findings pave the way for future research into next-generation, tailor-made, GAG-based antiviral agents, against SARS-CoV-2 and other members of the Coronaviridae.

biochemistry↗

bioRxiv2020

Heparin inhibits cellular invasion by SARS-CoV-2: structural dependence of the interaction of the surface protein (spike) S1 receptor binding domain with heparin.

The dependence of the host on the interaction of hundreds of extracellular proteins with the cell surface glycosaminoglycan heparan sulphate (HS) for the regulation of homeostasis is exploited by many microbial pathogens as a means of adherence and invasion. The closely related polysaccharide heparin, the widely used anticoagulant drug, which is structurally similar to HS and is a common experimental proxy, can be expected to mimic the properties of HS. Heparin prevents infection by a range of viruses if added exogenously, including S-associated coronavirus strain HSR1. Heparin prevents infection by a range of viruses if added exogenously, including S-associated coronavirus strain HSR1. Here, we show that the addition of heparin to Vero cells between 6.25 - 200 g.ml-1, which spans the concentration of heparin in therapeutic use, and inhibits invasion by SARS-CoV-2 at between 44 and 80%. We also demonstrate that heparin binds to the Spike (S1) protein receptor binding domain and induces a conformational change, illustrated by surface plasmon resonance and circular dichroism spectroscopy studies. The structural features of heparin on which this interaction depends were investigated using a library of heparin derivatives and size-defined fragments. Binding is more strongly dependent on the presence of 2-O or 6-O sulphation, and the consequent conformational consequences in the heparin structure, than on N-sulphation. A hexasaccharide is required for conformational changes to be induced in the secondary structure that are comparable to those that arise from heparin binding. Enoxaparin, a low molecular weight clinical anticoagulant, also binds the S1 RBD protein and induces conformational change. These findings have implications for the rapid development of a first-line therapeutic by repurposing heparin as well as for next-generation, tailor-made, GAG-based antiviral agents against SARS-CoV-2 and other members of the Coronaviridae.

biochemistry↗

bioRxiv2019

A glycosaminoglycan extract from Portunus pelagicus inhibits BACE1, the β secretase implicated in Alzheimer’s disease

Therapeutic options for Alzheimers disease, the most common form of dementia, are currently restricted to palliative treatments. The glycosaminoglycan heparin, widely used as a clinical anticoagulant, has previously been shown to inhibit the Alzheimers disease-relevant {beta}-secretase 1 (BACE1). Despite this, the deployment of pharmaceutical heparin for the treatment of Alzheimers disease is largely precluded by its potent anticoagulant activity. Furthermore, ongoing concerns regarding the use of mammalian sourced heparins, primarily due to prion diseases and religious beliefs, hinder the deployment of alternative heparin based therapeutics. A marine-derived, heparan sulphate-containing glycosaminoglycan extract isolated from the crab Portunus pelagicus, was identified to inhibit human BACE1 with comparable bioactivity to that of mammalian heparin (IC50 = 1.85 g.mL-1 (R2 = 0.94) and 2.43 g.mL-1 (R2 = 0.93), respectively) possessing highly attenuated anticoagulant activities. The results from several structural techniques suggest that the interactions between BACE1 and the extract from P. pelagicus are complex and distinct from those of heparin.

biochemistry↗

bioRxiv2019

Analysis of solid-state heparin samples by ATR-FTIR spectroscopy

The widely used anticoagulant pharmaceutical, heparin, is a polydisperse, heterogeneous polysaccharide. Heparin is one of the essential medicines defined by the World Health Organisation but, during 2007-2008, was the subject of adulteration. The intrinsic heterogeneity and variability of heparin makes it a challenge to monitor its purity by conventional means. This has led to the adoption of alternative approaches for its analysis and quality control, some of which are based on multivariate analysis of 1H NMR spectra, or exploit correlation techniques. Such NMR spectroscopy-based analyses, however, require costly and technically demanding NMR instrumentation. Here, an alternative approach based on the use of attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR) combined with multivariate analysis is proposed. FTIR-ATR employs more affordable and easy-to-use technology and, when combined with multivariate analysis of the resultant spectra, readily differentiates between glycosaminoglycans of different types, between heparin samples of distinct animal origins and enables the detection of both known heparin contaminants, such as over-sulphated chondroitin sulfate (OSCS), as well as other alien sulphated polysaccharides in heparin samples to a degree of sensitivity comparable to that achievable by NMR. The approach will permit the rapid and cost-effective monitoring of pharmaceutical heparin at any stage of the production process and indeed, in principle, the quality control of any heterogeneous or variable material.

biochemistry↗