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Probing Multivalent Lectin-Carbohydrate Binding via Multifunctional Glycan-Gold Nanoparticles: Implications for Blocking Virus Infection

preprint
submitted on 26.06.2020 and posted on 29.06.2020 by Darshita Budhadev, Emma Poole, Inga Nehlmeier, Yuanyuan Liu, James Hooper, Elizabeth Kalverda, Uchangi Satyaprasad Akshath, Nicole Hondow, W. Bruce Turnbull, Stefan Pöhlmann, Yuan Guo, Dejian Zhou
Multivalent lectin-glycan interactions are widespread in biology and are often exploited by pathogens to bind and infect host cells. Glycoconjugates can block such interactions and thereby prevent infection. The inhibition potency strongly depends on matching the spatial arrangement between the multivalent binding partners. However, the structural details of some key lectins remain unknown and different lectins may exhibit overlapping glycan specificity. This makes it difficult to design a glycoconjugate that can potently and specifically target a particular multimeric lectin for therapeutic interventions, especially under the challenging in vivo conditions. Conventional techniques such as surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) can provide quantitative binding thermodynamics and kinetics. However, they cannot reveal key structural information, e.g. lectin’s binding site orientation, binding mode, and inter-binding site spacing, which are critical to design specific multivalent inhibitors. Herein we report that gold nanoparticles (GNPs) displaying a dense layer of simple glycans are powerful mechanistic probes for multivalent lectin-glycan interactions. They can not only quantify the GNP-glycan-lectin binding affinities via a new fluorescence quenching method, but also reveal drastically different affinity enhancing mechanisms between two closely-related tetrameric lectins, DC-SIGN (simultaneous binding to one GNP) and DC-SIGNR (inter-crosslinking with multiple GNPs), via a combined hydrodynamic size and electron microscopy analysis. Moreover, a new term, potential of assembly formation (PAF) has been proposed to successfully predict the assembly outcomes based on the binding mode between GNP-glycans and lectins. Finally, the GNP-glycans can potently and completely inhibit DC-SIGN-mediated augmentation of Ebola virus glycoprotein-driven cell entry (with IC50 values down to 95 pM), but only partially block DC-SIGNR-mediated virus infection. Our results suggest that the ability of a glycoconjugate to simultaneously block all binding sites of a target lectin is key to robust inhibition of viral infection.

Funding

UK Biotechnology and Biological Sciences Research Council (grant no: BB/R007829/1)

EU Horizon 2020 via a Marie Sklodowska-Curie Fellowship (grant no: 797597)

UK Engineering and Physical Sciences Research Council doctoral training programme (grant no: EP/M50807X/1)

History

Email Address of Submitting Author

d.zhou@leeds.ac.uk

Institution

University of Leeds

Country

United Kingdom

ORCID For Submitting Author

0000-0003-3314-9242

Declaration of Conflict of Interest

The authors declare no competing financial interests.

Version Notes

The first version of this manuscript

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