Roles of the RGG Domain and RNA Recognition Motif\nof Nucleolin in G‑Quadruplex Stabilization

Abstract

G-quadruplexes have\nimportant biologic functions that are regulated\nby G-quadruplex-binding proteins. In particular, G-quadruplex structures\nare folded or unfolded by their binding proteins and affect transcription\nand other biologic functions. Here, we investigated the effect of\nthe RNA recognition motif (RRM) and arginine–glycine–glycine\nrepeat (RGG) domain of nucleolin on G-quadruplex formation. Our findings\nindicate that Phe in the RGG domain of nucleolin is responsible for\nG-quadruplex binding and folding. Moreover, the RRM of nucleolin potentially\nbinds to a guanine-rich single strand and folds the G-quadruplex with\na 5′-terminal and 3′-terminal single strand containing\nguanine. Our findings contribute to our understanding of how the RRM\nand RGG domains contribute to G-quadruplex folding and unfolding.