Characterization of DNA bound cyclic GMP-AMP synthase using atomic force microscopy imaging.

The protocol described herein allows for acquiring topography images of DNA-protein complexes using Atomic Force Microscopy imaging. Since the very beginning of this method, AFM has been an indispensable tool for characterization of biomolecular complexes with exceptional capability of observing single complexes. This method can visualize structural characteristics of DNA-protein assemblies and evaluate differences between individual complexes. Although this protocol is generally applicable to a large number of various proteins complexed with DNA, we use cyclic G/AMP synthase (cGAS) enzyme as a case study for the protocol description.