title: Nucleoplasmin binds histone H2A-H2B dimers through its distal face.
abstract: Nucleoplasmin (NP) is a pentameric chaperone that regulates the condensation state of chromatin extracting specific basic proteins from sperm chromatin and depositing H2A-H2B histone dimers. It has been proposed that histones could bind to either the lateral or distal face of the pentameric structure. Here, we combine different biochemical and biophysical techniques to show that natural, hyperphosphorylated NP can bind five H2A-H2B dimers and that the amount of bound ligand depends on the overall charge (phosphorylation level) of the chaperone. Three-dimensional reconstruction of NP/H2A-H2B complex carried out by electron microscopy reveals that histones interact with the chaperone distal face. Limited proteolysis and mass spectrometry indicate that the interaction results in protection of the histone fold and most of the H2A and H2B C-terminal tails. This structural information can help to understand the function of NP as a histone chaperone.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencia y Tecnología, Universidad del País Vasco, 48080 Bilbao, Spain.
authors.forename: Isbaal
authors.initials: I
authors.lastname: Ramos
authors.forename: Jaime
authors.initials: J
authors.lastname: Martín-Benito
authors.forename: Ron
authors.initials: R
authors.lastname: Finn
authors.forename: Laura
authors.initials: L
authors.lastname: Bretaña
authors.forename: Kerman
authors.initials: K
authors.lastname: Aloria
authors.forename: Jesús M
authors.initials: JM
authors.lastname: Arizmendi
authors.forename: Juan
authors.initials: J
authors.lastname: Ausió
authors.forename: Arturo
authors.initials: A
authors.lastname: Muga
authors.forename: José M
authors.initials: JM
authors.lastname: Valpuesta
authors.forename: Adelina
authors.initials: A
authors.lastname: Prado
mesh_terms: D000818:Animals; D019281:Dimerization; D006657:Histones / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D056489:Nucleoplasmins / Q000737:chemistry*; D010766:Phosphorylation; D017510:Protein Folding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D014982:Xenopus laevis / Q000378:metabolism
chemical_list: D006657:Histones; D056489:Nucleoplasmins