title: Nucleosome formation activity of human somatic nuclear autoantigenic sperm protein (sNASP).
abstract: NASP (nuclear autoantigenic sperm protein) is a member of the N1/N2 family, which is widely conserved among eukaryotes. Human NASP reportedly prefers to bind to histones H3.H4 and the linker histone H1, as compared with H2A.H2B, and is anticipated to function as an H3.H4 chaperone for nucleosome assembly. However, the direct nucleosome assembly activity of human NASP has not been reported so far. In humans, two spliced isoforms, somatic and testicular NASPs (sNASP and tNASP, respectively) were identified. In the present study we purified human sNASP and found that sNASP efficiently promoted the assembly of nucleosomes containing the conventional H3.1, H3.2, H3.3, or centromere-specific CENP-A. On the other hand, sNASP inefficiently promoted nucleosome assembly with H3T, a testis-specific H3 variant. Mutational analyses revealed that the Met-71 residue of H3T is responsible for this inefficient nucleosome formation by sNASP. Tetrasomes, composed of the H3.H4 tetramer and DNA without H2A.H2B, were efficiently formed by the sNASP-mediated nucleosome-assembly reaction. A deletion analysis of sNASP revealed that the central region, amino acid residues 26-325, of sNASP is responsible for nucleosome assembly in vitro. These experiments are the first demonstration that human NASP directly promotes nucleosome assembly and provide compelling evidence that sNASP is a bona fide histone chaperone for H3.H4.
authors.affiliation: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan.
authors.forename: Akihisa
authors.initials: A
authors.lastname: Osakabe
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tachiwana
authors.forename: Takaaki
authors.initials: T
authors.lastname: Matsunaga
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Shiga
authors.forename: Ryu-Suke
authors.initials: RS
authors.lastname: Nozawa
authors.forename: Chikashi
authors.initials: C
authors.lastname: Obuse
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kurumizaka
mesh_terms: D017398:Alternative Splicing; D019943:Amino Acid Substitution; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D013094:Spermatozoa / Q000276:immunology / Q000378:metabolism; D013737:Testis / Q000276:immunology / Q000378:metabolism; D012359:tRNA Methyltransferases
chemical_list: D001324:Autoantigens; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D017931:DNA Primers; D006657:Histones; C489390:NASP protein, human; D009687:Nuclear Proteins; D009707:Nucleosomes; D011506:Proteins; D011994:Recombinant Proteins; C498548:TRMO protein, human; D012359:tRNA Methyltransferases