Related Experiment Video
Updated: Oct 8, 2025

Single-molecule Manipulation of G-quadruplexes by Magnetic Tweezers
Published on: September 19, 2017
Thermal Stability Changes in Telomeric G-Quadruplex Structures Due to N6-Methyladenine Modification
Ryohei Wada1, Wataru Yoshida1,2
1School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan.
Abstract:
N6-methyladenine modification (m6dA) has recently been identified in eukaryote genomic DNA. The methylation destabilizes the duplex structure when the adenine forms a Watson-Crick base pair, whereas the methylation on a terminal unpaired adenine stabilizes the duplex structure by increasing the stacking interaction. In this study, the effects of m6dA modification on the thermal stability of four distinct telomeric G-quadruplex (G4) structures were investigated. The m6dA-modified telomeric oligonucleotide d[AGGG(TTAGGG)3] that forms a basket-type G4 in Na+, d[(TTAGGG)4TT] that forms a hybrid-type G4 in K+ (Form-2), d[AAAGGG(TTAGGG)3AA] that forms a hybrid-type G4 in K+ (Form-1), and d[GGG(TTAGGG)3T] that forms a basket-type G4 with two G-tetrads in K+ (Form-3) were analyzed. Circular dichroism melting analysis demonstrated that (1) A7- and A19-methylation destabilized the basket-type G4 structure that formed in Na+, whereas A13-methylation stabilized the structure; (2) A15-methylation stabilized the Form-2 G4 structure; (3) A15- and A21-methylations stabilized the Form-1 G4 structure; and (4) A12-methylation stabilized the Form-3 G4 structure. These results suggest that m6dA modifications may affect the thermal stability of human telomeric G4 structures in regulating the biological functions.
Related Concept Videos
RNA Stability
Telomeres and Telomerase
mRNA Stability and Gene Expression
Cis-acting Elements involved in mRNA stability
Transfer RNA Synthesis
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Spontaneous and Induced Mutations
Proofreading

