Structure Studies on DNA Processing Enzymes

The intricate interplay between protein and DNA governs many aspects of the cellular life. While DNA encodes genetic instructions that guide protein production and regulation, proteins confer and orchestrate biological functions, including maintaining DNA integrity and regulating gene expression. Specifically, DNA processing enzymes and DNA binding proteins play key roles in DNA metabolism and gene regulation. Understanding how they work at the molecular level is essential for elucidating fundamentals in biology and developing novel biotechnologies. This dissertation investigates the structures and dynamics of three distinct DNA processing proteins involved in DNA replication, DNA repair and transcription regulation, respectively. Specifically, we utilize crystallography and cryo-electron microscopy to elucidate the structural basis of fidelity in a family B DNA polymerase. We use dynamic crystallography to interrogate the light-induced responses in a DNA photolyase. Finally, we apply temperature-scan cryo-trapping crystallography to reveal early molecular events in a B12-based light-sensitive transcription regulator. Together, these studies highlight the importance of structural and dynamic analysis for mechanistic understanding of protein function beyond static structures.