Figure 6.

Possible role of G-quadruplexes in the antiviral mechanism and pathogenicity. Left part, G-quadruplexes can function as inhibition elements in the SARS-CoV-2 life cycle. Both the replication and translation could be affected by the G-quadruplex structures. The stable G-quadruplex structures in the 3′ end of the negative-sense strand may interfere with the activity of RdRp; hence, the replication of the negative-sense strands to the positive-sense strands is repressed, so that the SARS-CoV-2 genomes cannot be produced in large quantities. The G-quadruplex structures can suppress the translation process by impairing the elongating of ribosomes, which can hinder the production of proteins required for the virus. The G-quadruplex structures could be stabilized by the specific ligands to enhance the inhibitory effects, which is a promising antiviral strategy. Right part, a possible mechanism for SARS-CoV-2 to impede the expression of human genes. G-quadruplex structures, particularly with longer G-stretches, are the potential binding targets for the G-quadruplex binding domain in SARS-CoV-2, and the interaction of the G-quadruplex binding domain of SARS-CoV-2 with G-quadruplex structures possibly leads to the transcript instability or obstructing of the translation efficiency.