title: Vertebrate Spt2 is a novel nucleolar histone chaperone that assists in ribosomal DNA transcription.
abstract: In eukaryotes, transcription occurs in the chromatin context with the assistance of histone-binding proteins, such as chromatin/nucleosome remodeling factors and histone chaperones. However, it is unclear how each remodeling factor or histone chaperone functions in transcription. Here, we identify a novel histone-binding protein, Spt2, in higher eukaryotes. Recombinant human Spt2 binds to histones and DNA, and promotes nucleosome assembly in vitro. Spt2 accumulates in nucleoli and interacts with RNA polymerase I in chicken DT40 cells, suggesting its involvement in ribosomal RNA transcription. Consistently, Spt2-deficient chicken DT40 cells are sensitive to RNA polymerase I inhibitors and exhibit decreased transcription activity, as shown by a transcription run-on assay. Domain analyses of Spt2 revealed that the C-terminal region, containing the region homologous to yeast Spt2, is responsible for histone binding, while the central region is essential for nucleolar localization and DNA binding. Based on these results, we conclude that vertebrate Spt2 is a novel histone chaperone with a separate DNA-binding domain that facilitates ribosomal DNA transcription through chromatin remodeling during transcription.
authors: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.
authors: Akihisa
authors: A
authors: Osakabe
authors: Hiroaki
authors: H
authors: Tachiwana
authors: Motoki
authors: M
authors: Takaku
authors: Tetsuya
authors: T
authors: Hori
authors: Chikashi
authors: C
authors: Obuse
authors: Hiroshi
authors: H
authors: Kimura
authors: Tatsuo
authors: T
authors: Fukagawa
authors: Hitoshi
authors: H
authors: Kurumizaka
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002645:Chickens; D042002:Chromatin Assembly and Disassembly / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D056488:Histone Chaperones / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport / Q000235:genetics; D012318:RNA Polymerase I / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics; D014158:Transcription, Genetic; D015003:Yeasts / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D056488:Histone Chaperones; D006657:Histones; C585049:SPTY2D1 protein, human; D012318:RNA Polymerase I
keywords: Chromatin; Histone chaperone; Nucleoli; Nucleosome; RNA polymerase I; Transcription