Probing and manipulating viral receptor-sugar interactions using novel DNA-based multivalent carbohydrate ligands. (360G-Wellcome-097354_Z_11_Z)

Our previous work suggests that tetrameric viral-binding receptors, dendritic cell receptor DC-SIGN and closely related endothelia cell receptor DC-SIGNR, employ a new strategy in interacting with viral (e.g. HIV, HCV and Ebolas viruses) surface glycoproteins via adjusting their flexible CRDs to achieve selective, high affinity binding. The key goals here are 1) to verify CRD reorganisation in DC-SIGN/R upon ligand-binding; 2) to unravel the molecular basis of different multi-sugar ligand bindin g and HIV transmission efficiencies in DC-SIGN and DC-SIGNR; and 3) to develop effective inhibitors for blocking DC-SIGN-HIV interaction and hence prevent primary infection. I will develop novel DNA-based multivalent sugar ligands where the sugars are attached to rigid DNA scaffold and therefore having well-defined and adjustable inter-sugar distances via changing the DNA scaffold length. The CRD flexibility will be studied by comparing binding affinities of receptors to different spaced sugar -ligands by calorimetry and SPR. Direct CRD movement will be investigated by measuring FRET-pair labelled CRD distances before and after ligand binding using single-molecule FRET. Molecular basis for structural difference between DC-SIGN and DC-SIGNR will be elucidated from mutagenesis studies. Inhibition efficiency of the DNA-based ligands to DC-SIGN-HIV interaction will be evaluated by competition assays in a cellular context.