DNA conformations in mismatch repair probed in solution by X-ray scattering from gold nanocrystals

Significance We developed and applied nanogold labels for DNA complexes with proteins examined by small angle X-ray scattering (SAXS) to follow DNA conformations acting in error detection by the mismatch repair (MMR) system in solution. This technique can examine short or long pieces of DNA and in most solution conditions, including those closest to cellular environments. Thus, we expect the technique to be useful for many biologically important systems involving DNA complexes and conformations. Specifically, we reveal DNA bending followed by straightening by the repair protein MutS at the site of a mismatch as a suitable mechanism for error detection and signaling needed to avoid mutations and cancers and to control microbial stability and evolution in response to environmental stress.