C-Rich Sequence in a Non-Template DNA Strand Regulates Structure Change of G-Quadruplex in a Template Strand during Transcription

Abstract

Abstract To understand the mechanism for formation of non-canonical nucleic acid structures, especially G-quadruplexes, is important for gene expression because the G-quadruplexes inhibit efficiently biological reactions. In this study, we utilized a fluorescent G-quadruplex ligand to quantitatively monitor G-quadruplex formation and dissociation in six different G-rich templates during transcription. Interestingly, increased and decreased G-quadruplex formation were observed depending on the sequence contexts. The formation of G-quadruplex was related to stabilization of the G-quadruplex after unwinding of the templates by the surrounding environment, while dissociation of the G-quadruplex was related to the potential triplet structures formed between C-rich sequences in the non-template strand and G-rich sequences in the template strand. The interaction between the template and non-template strand plays an important role in regulating G-quadruplex formation and dissociation in the template strand, which affects gene expression.