High-resolution AFM structure of DNA G-wires in aqueous solution.

ABSTRACT: We investigate the self-assembly of short pieces of the Tetrahymena telomeric DNA sequence d[G4T2G4] in physiologically relevant aqueous solution using atomic force microscopy (AFM). Wire-like structures (G-wires) of 3.0?nm height with well-defined surface periodic features were observed. Analysis of high-resolution AFM images allowed their classification based on the periodicity of these features. A major species is identified with periodic features of 4.3?nm displaying left-handed ridges or zigzag features on the molecular surface. A minor species shows primarily left-handed periodic features of 2.2?nm. In addition to 4.3 and 2.2?nm ridges, background features with periodicity of 0.9?nm are also observed. Using molecular modeling and simulation, we identify a molecular structure that can explain both the periodicity and handedness of the major G-wire species. Our results demonstrate the potential structural diversity of G-wire formation and provide valuable insight into the structure of higher-order intermolecular G-quadruplexes. Our results also demonstrate how AFM can be combined with simulation to gain insight into biomolecular structure.

SUBMITTER: Bose K 

PROVIDER: S-EPMC5958085 | biostudies-other | 2018 May

REPOSITORIES: biostudies-other