Cholesterol Recognition Motifs (CRAC) in the S Protein of Coronavirus: A Possible Target for Antiviral Therapy?

Some interactions of enveloped viruses with the host cell membrane have a cholesterol-dependent component, which may account for clinical manifestations of the infectious disease and can be used for the development of antiviral drugs. These cholesterol-dependent interactions can be mediated by cholesterol-recognition amino-acid consensus (CRAC) motifs present in viral proteins. The S protein of the SARS-CoV and SARS-CoV2 coronaviruses contains CRAC motifs that can be involved in the process of virus entry into the cell. Besides, during viral envelope formation, CRAC motifs can be responsible for binding of cell membrane cholesterol, leading to depletion of cell membrane cholesterol and subsequent malfunctioning of cellular cholesterol-dependent proteins, destabilization and permeabilization of cell membranes and, ultimately, to the death of infected cells. Understanding the mechanisms of cholesterol-dependent virus–cell interactions and the role of CRAC-containing viral proteins in the pathogenesis of the disease can serve as the basis for the development of new drugs that prevent both coronavirus entry into the cell and the damage of the infected cell during the viral morphogenesis. The target for such drugs can be the S-protein/cholesterol interface. CRAC-containing peptides derived from viral proteins may be among these agents. These peptides can also be used as experimental tools to study cholesterol-dependent virus–cell interactions.