Caractérisation structurale et biophysique de l’impact de l’acétylation de SUMO1 sur son interaction dépendante de la phosphorylation avec PML
PML-Nuclear Bodies (PML-NBs) formation and dynamics is regulated by an extensive network of post-translational modifications (PTMs), which includes SUMOylation of PMLNB- resident proteins, phosphorylation of SIMs (SUMO-Interacting Motifs) and acetylation of SUMO proteins. Recent studies suggest that acetylation of SUMO proteins regulates PML-NB function, but the precise role of acetylation is still not clear. Using Isothermal Titration Calorimetry (ITC) and X-ray crystallography studies, we have investigated the impact of SUMO1 acetylation on its interaction with the phospho SIMs of PML and Daxx. Interestingly, neutralizing the positive charges of K37, K39, K45 or K46 by either acetylation or glutamine substitution significantly decreases the binding affinity towards phospho-mimetic PML-SIMs as measured by ITC, but the decreases are more dramatic with the K39 and K46 variants than with the K37 and K45 variants. In the crystal structures of the phospho-SIMs of PML and Daxx in complex with K46Ac, there are dramatic disruptions of interactions at the binding interfaces, but the changes that occur at the interface appear to be distinct for the SIM involved. The other acetylated variants in complex with the phospho-SIM of PML displayed a more global effect of charge re-organization at the binding interface. Together, our results provide an atomic level description of how SUMO1 acetylation can modulate its interaction with different phospho-SIMs, indicating that there is considerable plasticity in SUMO/SIM interactions and this plasticity could be altered by different types of PTMs in order to regulate distinct cellular functions.
SUMO PML SUMOylation X-ray crystallography ITC PML-NBs SIM tumor suppressor phospho-sérines phosphoserines X-ray crystallography Isothermal Titration Calorimetry (ITC) PML-Nuclear Bodies (PML-NBs) SUMO-Interacting Motif (SIM) Tumour suppressor Phosphoserines