title: A unique vertebrate histone H1-related protamine-like protein results in an unusual sperm chromatin organization.
abstract: Protamine-like proteins constitute a group of sperm nuclear basic proteins that have been shown to be related to somatic linker histones (histone H1 family). Like protamines, they usually replace the chromatin somatic histone complement during spermiogenesis; hence their name. Several of these proteins have been characterized to date in invertebrate organisms, but information about their occurrence and characterization in vertebrates is still lacking. In this sense, the genus Mullus is unique, as it is the only known vertebrate that has its sperm chromatin organized by virtually only protamine-like proteins. We show that the sperm chromatin of this organism is organized by two type I protamine-like proteins (PL-I), and we characterize the major protamine-like component of the fish Mullus surmuletus (striped red mullet). The native chromatin structure resulting from the association of these proteins with DNA was studied by micrococcal nuclease digestion as well as electron microscopy and X-ray diffraction. It is shown that the PL-I proteins organize chromatin in parallel DNA bundles of different thickness in a quite distinct arrangement that is reminiscent of the chromatin organization of those organisms that contain protamines (but not histones) in their sperm.
authors.affiliation: Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Saperas
authors.forename: Manel
authors.initials: M
authors.lastname: Chiva
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Casas
authors.forename: J Lourdes
authors.initials: JL
authors.lastname: Campos
authors.forename: José M
authors.initials: JM
authors.lastname: Eirín-López
authors.forename: Lindsay J
authors.initials: LJ
authors.lastname: Frehlick
authors.forename: Cèlia
authors.initials: C
authors.lastname: Prieto
authors.forename: Juan A
authors.initials: JA
authors.lastname: Subirana
authors.forename: Juan
authors.initials: J
authors.lastname: Ausió
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002843:Chromatin / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D006657:Histones / Q000737:chemistry*; D008297:Male; D008969:Molecular Sequence Data; D049880:Mytilus edulis; D009687:Nuclear Proteins / Q000737:chemistry*; D010473:Perciformes; D011479:Protamines / Q000737:chemistry*; D013094:Spermatozoa / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D002843:Chromatin; D006657:Histones; D009687:Nuclear Proteins; D011479:Protamines; D004247:DNA