Single Molecule Imaging of Proteins That Recognize and Repair DNA Damages

Double-stranded DNA breaks are common cytotoxic lesions that can be repaired by several well-known repair pathways. One of the most prominent repair strategies is homologous recombination (HR). Over the years, HR has been studied primarily through biochemical analysis. However, recent advances in single molecule techniques have enabled researchers to investigate the repair mechanisms at the single protein level, with nanometer resolution and millisecond time scale. The ability to fluorescently label different regions of the protein or protein complex allows real-time monitoring of conformational changes, as well as detailed mechanisms with which the proteins target DNA damage and conduct repair. Here, we review some recent single molecule studies that provide new insights into the molecular mechanisms involved in mismatch and homologous repair of DNA.