The transcription factor p53 plays a key role in cell cycle arrest, DNA repair, apoptosis, tumor suppression, and maintaining cellular homeostasis. Under cellular stress, p53 directly interacts with the Forkhead box O (FOXO) 4 transcription factor, thereby upregulating the expression of the p21 gene, resulting in the induction of cellular senescence. However, the detailed molecular mechanism behind FOXO4-p53 interaction remains unclear due to the unavailability of structural data. Therefore, main goal of this doctoral thesis was the characterization of the interaction between FOXO4 and p53 using several biophysical techniques including sedimentation velocity analytical ultracentrifugation (SV AUC), nuclear magnetic resonance (NMR) spectroscopy and chemical cross-linking coupled to mass spectrometry. Furthermore, we also investigated the DNA binding properties of both proteins with their respective consensus DNA sequences in the presence or absence of their binding partners by fluorescence anisotropy measurements along with the comparison of p53-binding surfaces of the Forkhead domain of three different FOXO proteins by NMR spectroscopy. In addition, we also optimized small molecule compounds for the inhibition of FOXO3-DNA interaction. Our results revealed that the p53 interacts with FOXO4 through...
