The transcription factor p53 protects cells against tumorogenesis when exposed to various cellular stresses. Under these conditions, p53 interacts with the transcription factor FOXO4 to induce cellular senescence, a condition contributing significantly to the aging process, by upregulating the transcription of the senescence-associated protein p21 [1]. However, the structural details of FOXO4:p53 interaction still remain unclear. Inhibition of this interaction has been shown to help restore homeostasis of senescent tissues and counteract signs of aging, making it a target for the design of senolytic compounds [2].
In previous published work, we characterized the FOXO4:p53 binding interface and showed that the DNA-binding domain (DBD) of FOXO4 and the transactivation domain (TAD) of p53 are essential for the stability of this protein-protein complex [3]. In this work, we characterize the interaction between p53TAD and FOXO4-DBD. We first determined the affinity of the complex using fluorescence anisotropy measurements. Subsequently, we performed a set of paramagnetic relaxation rate enhancement experiments (PRE) combined with 15N relaxation experiments. The PRE results allowed us to derive a set of distance constraints that, together with R2/R1 values obtained from 15N relaxation experiments and significant CSP values from the 1H-15N HSQC titrations, were used to build a HADDOCK model of the FOXO4-DBD:p53-TAD complex.
Our structural insights may help to
understand the interrelated functions of FOXO4 and p53 in cellular homeostasis,
longevity, and stress response, as well as to further help the develepment of
senolytic compounds.
This work was supported by Czech Science Foundation Grant No. 21-02080S, the Grant agency of the Charles University (project number: 296621) and the Czech Academy of Sciences (Research Project RVO: 67985823 of the Institute of Physiology).