title: Role of mutual interactions in the chemical and thermal stability of nucleophosmin NPM1 domains.
abstract: Nucleophosmin (NPM1) is a key factor involved in fundamental biological processes. Mutations involving the NPM1 gene are the most frequent molecular alterations in acute myeloid leukemia. Here we report a biophysical characterization of NPM1 and of its domains in order to gain insights into the role that inter-domain interactions plays in the protein stabilization. Thermal denaturation analyses show that the N-terminal domain is endowed with an exceptional thermal stability, as it does not unfold in the investigated temperature range (20-105°C). This finding is corroborated by chemical denaturation experiments showing that this domain is not significantly affected by the addition of 8M urea. These results are consistent with the chaperone function of NPM1. In line with literature data, the other folded domain of the NPM1, a 3-helix bundle domain located at the C-terminus, shows a lower stability. Interestingly, the chemical and thermal stability of this latter domain, which embeds natural mutations related to acute myeloid leukemia, is influenced by the presence of other regions of the protein. Small but significant stabilizations of the C-terminal 3-helix bundle are provided by the adjacent unfolded fragment as well as by the rest of the protein.
authors.affiliation: Institute of Biostructures and Bioimaging, CNR via Mezzocannone 16, I-80134 Napoli, Italy. daniela.marasco@unina.it
authors.forename: Daniela
authors.initials: D
authors.lastname: Marasco
authors.forename: Alessia
authors.initials: A
authors.lastname: Ruggiero
authors.forename: Carlo
authors.initials: C
authors.lastname: Vascotto
authors.forename: Mattia
authors.initials: M
authors.lastname: Poletto
authors.forename: Pasqualina Liana
authors.initials: PL
authors.lastname: Scognamiglio
authors.forename: Gianluca
authors.initials: G
authors.lastname: Tell
authors.forename: Luigi
authors.initials: L
authors.lastname: Vitagliano
mesh_terms: D000595:Amino Acid Sequence; D006361:Heating; D006801:Humans; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics; D000090243:Nucleophosmin; D011489:Protein Denaturation; D055503:Protein Multimerization; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D018832:Molecular Chaperones; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D000090243:Nucleophosmin