Room-temperature apo structure of human SIRT2 solved by X-ray crystallography and its application in targeted cancer drug development

Sirtuins are a family of NAD⁺-dependent deacetylases that regulate gene expression through histone modification and play crucial roles in cellular processes such as stress response, metabolism, aging, and cancer. Among the seven mammalian isoforms (SIRT1–SIRT7), SIRT2 is unique in its ability to function in both the nucleus and cytoplasm, modulating the acetylation status of key regulatory proteins involved in cell cycle control. This regulation implicates SIRT2 in tumorigenesis and the development of drug resistance. In this study, we report the ambient-temperature apo structure of human SIRT2 determined by X-ray crystallography, providing a physiologically relevant model that captures the enzyme's intrinsic conformational flexibility under near-native conditions. Compared to traditional cryogenic structures, the room-temperature data reveal a narrower, likely inactive conformation of the inhibitor binding pocket and active site which undergoes expansion upon ligand binding. Comparative structural analyses identify key residues critical for ligand interactions and highlight the dynamic interplay between protein flexibility, temperature, and ligand presence. These insights significantly deepen our understanding of SIRT2's functional mechanism and are vital for the rational design of selective inhibitors. By integrating ambient-temperature structural data, this work establishes a foundation for structure-based drug discovery targeting SIRT2, advancing efforts in the development of targeted cancer therapeutics. Moreover, these findings emphasize the importance of considering physiological flexibility in proteins to improve the effectiveness and specificity of novel drugs.