High-Resolution Atomic Force Microscopy Imaging of RNA Molecules in Solution.

Atomic force microscopy (AFM) is an important and versatile technique to investigate the structures and dynamics of biomolecules under physiologically relevant conditions at the single-molecule level. Recent progresses in high-resolution AFM imaging of nucleic acids have expanded this technique from simple characterization of double-stranded DNA or RNA to detailed analyses of the structure and dynamics of large functional RNAs with complex folds. Several technical developments, such as sharper probes and more stable instruments with novel imaging modes, AFM is capable of directly visualizing RNA conformational heterogeneity in solution in real time. Here, we introduce a comprehensive method for recording high-resolution images of RNA molecules, including sample preparation, instrument setup, data acquisition, and image processing.