Such a dual receptor model, consistent with the topology of the SARS-CoV-2 S protein, is proposed in Fig. 8 . With this model in mind, the potential effects of CLQ and CLQ-OH were studied, both of which, according to the molecular modelling data, have a high affinity for sialic acids and gangliosides.
Fig. 8 Dual recognition of gangliosides and angiotensin-converting enzyme-2 (ACE-2) by SARS-CoV-2 spike (S) protein. The viral protein displays two distinct domains, the tips of which are available for distinct types of interactions. The receptor-binding domain binds to the ACE-2 receptor, and the N-terminal domain (NTD) binds to the ganglioside-rich domain of the plasma membrane. Lipid rafts, which are membrane domains enriched in gangliosides (in yellow) and cholesterol (in blue), provide a perfect attractive interface for adequately positioning the viral S protein at the first step of the infection process. These structural and molecular modelling studies suggest that amino acid residues 111–162 of the NTD form a functional ganglioside-binding domain, the interaction of which with lipid rafts can be efficiently prevented by chloroquine and hydroxychloroquine.