title: Impact of Ser17 Phosphorylation on the Conformational Dynamics of the Oncoprotein MDM2.
abstract: MDM2 is an important oncoprotein that downregulates the activity of the tumor suppressor protein p53 via binding of its N-terminal domain to the p53 transactivation domain. The first 24 residues of the MDM2 N-terminal domain form an intrinsically disordered "lid" region that interconverts on a millisecond time scale between "open" and "closed" states in unliganded MDM2. While the former conformational state is expected to facilitate p53 binding, the latter competes in a pseudo-substrate manner with p53 for its binding site. Phosphorylation of serine 17 in the MDM2 lid region is thought to modulate the equilibrium between "open" and "closed" lid states, but contradictory findings on the favored lid conformational state upon phosphorylation have been reported. Here, the nature of the conformational states of MDM2 pSer17 and Ser17Asp variants was addressed by means of enhanced sampling molecular dynamics simulations. Detailed analyses of the computed lid conformational ensembles indicate that both lid variants stabilize a "closed" state, with respect to wild type. Nevertheless, the nature of the closed-state conformational ensembles differs significantly between the pSer17 and Ser17Asp variants. Thus, care should be applied in the interpretation of biochemical experiments that use phosphomimetic variants to model the effects of phosphorylation on the structure and dynamics of this disordered protein region.
authors.affiliation: EaStCHEM School of Chemistry, The University of Edinburgh , Edinburgh, EH9 3FJ, United Kingdom.|Computational Biology, School of Life Sciences, School of Science and Engineering, University of Dundee , Dow Street, Dundee, DD1 5EH, United Kingdom.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Bueren-Calabuig
authors.affiliation: EaStCHEM School of Chemistry, The University of Edinburgh , Edinburgh, EH9 3FJ, United Kingdom.
authors.forename: Julien
authors.initials: J
authors.lastname: Michel
mesh_terms: D001665:Binding Sites; D006801:Humans; D056004:Molecular Dynamics Simulation; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D051736:Proto-Oncogene Proteins c-mdm2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D012694:Serine; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2