title: Histones and DNA compete for binding polyphosphoinositides in bilayers.
abstract: Recent discoveries on the presence and location of phosphoinositides in the eukaryotic cell nucleoplasm and nuclear membrane prompted us to study the putative interaction of chromatin components with these lipids in model membranes (liposomes). Turbidimetric studies revealed that a variety of histones and histone combinations (H1, H2AH2B, H3H4, octamers) caused a dose-dependent aggregation of phosphatidylcholine vesicles (large unilamellar vesicle or small unilamellar vesicle) containing negatively charged phospholipids. 5 mol % phosphatidylinositol-4-phosphate (PIP) was enough to cause extensive aggregation under our conditions, whereas with phosphatidylinositol (PI) at least 20 mol % was necessary to obtain a similar effect. Histone binding to giant unilamellar vesicle and vesicle aggregation was visualized by confocal microscopy. Histone did not cause vesicle aggregation in the presence of DNA, and the latter was able to disassemble the histone-vesicle aggregates. At DNA/H1 weight ratios 0.1-0.5 DNA- and PIP-bound H1 appear to coexist. Isothermal calorimetry studies revealed that the PIP-H1 association constant was one order of magnitude higher than that of PI-H1, and the corresponding lipid/histone stoichiometries were ~0.5 and ~1, respectively. The results suggest that, in the nucleoplasm, a complex interplay of histones, DNA, and phosphoinositides may be taking place, particularly at the nucleoplasmic reticula that reach deep within the nucleoplasm, or during somatic and nonsomatic nuclear envelope assembly. The data described here provide a minimal model for analyzing and understanding the mechanism of these interactions.
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain.
authors.forename: Marta G
authors.initials: MG
authors.lastname: Lete
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Sot
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain; Institut de Formation aux Carrieres de Sante de Rabat (IFCSR), Rabat, Morocco.
authors.forename: Hasna
authors.initials: H
authors.lastname: Ahyayauch
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain.
authors.forename: Noelia
authors.initials: N
authors.lastname: Fernández-Rivero
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain.
authors.forename: Adelina
authors.initials: A
authors.lastname: Prado
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain.
authors.forename: Félix M
authors.initials: FM
authors.lastname: Goñi
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain. Electronic address: alicia.alonso@ehu.es.
authors.forename: Alicia
authors.initials: A
authors.lastname: Alonso
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D004247:DNA / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D010716:Phosphatidylinositols / Q000378:metabolism*; D011485:Protein Binding; D053835:Unilamellar Liposomes / Q000737:chemistry / Q000378:metabolism
chemical_list: D006657:Histones; D008051:Lipid Bilayers; D010716:Phosphatidylinositols; D053835:Unilamellar Liposomes; D004247:DNA