title: Interaction of nucleoplasmin with core histones.
abstract: Nucleoplasmin is one of the most abundant proteins in Xenopus laevis oocytes, and it has been involved in the chromatin remodeling that takes place immediately after fertilization. This molecule has been shown to be responsible for the removal of the sperm-specific proteins and deposition of somatic histones onto the male pronuclear chromatin. To better understand the latter process, we have used sedimentation velocity, sedimentation equilibrium, and sucrose gradient fractionation analysis to show that the pentameric form of nucleoplasmin binds to a histone octamer equivalent consisting of equal amounts of the four core histones, H2A, H2B, H3, and H4, without any noticeable preference for any of these proteins. Removal of the histone N-terminal "tail" domains or the major C-terminal polyglutamic tracts of nucleoplasmin did not alter these binding properties. These results indicate that interactions other than those electrostatic in nature (likely hydrophobic) also play a critical role in the formation of the complex between the negatively charged nucleoplasmin and positively charged histones. Although the association of histones with nucleoplasmin may involve some ionic interactions, the interaction process is not electrostatically driven.
authors.affiliation: Departament d'Enginyeria Química, Escola Tècnica Superior d'Enginyers Industrials de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain.
authors.forename: Carme
authors.initials: C
authors.lastname: Arnan
authors.forename: Núria
authors.initials: N
authors.lastname: Saperas
authors.forename: Cèlia
authors.initials: C
authors.lastname: Prieto
authors.forename: Manel
authors.initials: M
authors.lastname: Chiva
authors.forename: Juan
authors.initials: J
authors.lastname: Ausió
mesh_terms: D000818:Animals; D002843:Chromatin / Q000378:metabolism; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D056489:Nucleoplasmins; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014982:Xenopus laevis
chemical_list: D002843:Chromatin; D006657:Histones; D009687:Nuclear Proteins; D056489:Nucleoplasmins; D010750:Phosphoproteins