title: Evidence that nucleosomes on the mouse mammary tumor virus promoter adopt specific translational positions.
abstract: We have previously demonstrated that an array of six nucleosomes are phased on the mouse mammary tumor virus (MMTV) long terminal repeat (1,2). In this study, we devised a new assay to measure the translational positions of specific nucleosomes on the MMTV promoter. Nucleosome core particles were purified and shown to contain A and B nucleosomal DNA by Taq polymerase primer extension with nucleosome-specific primers. The 5' and 3' boundaries of A and B nucleosomes were measured by extending to the end of the core DNA with internal primers. This approach yielded results consistent with major translational positions of -23 to +123 and -221 to -75 for A and B nucleosomes, respectively. The micrococcal nuclease cleavage patterns of A and B nucleosome regions in isolated nuclei are conserved at base-pair resolution in multiple murine cell lines containing either stable MMTV-reporter chimeras or endogenous proviruses. As the refined nucleosome positions place important transcription factor binding sites at the 3' edge of the B nucleosome and in the nucleosome A/B linker, we propose that linker histone depletion and chromatin unfolding may be required to expose these cis-elements during steroid hormone-induced transcription initiation.
authors.affiliation: Hormone Action & Oncogenesis Section, National Cancer Institute, Bethesda, MD 20892.
authors.forename: E H
authors.initials: EH
authors.lastname: Bresnick
authors.forename: C
authors.initials: C
authors.lastname: Rories
authors.forename: G L
authors.initials: GL
authors.lastname: Hager
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D022762:CCAAT-Enhancer-Binding Proteins; D002460:Cell Line; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D011905:Genes, ras / Q000235:genetics; D051863:Host Cell Factor C1; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics*; D008836:Micrococcal Nuclease / Q000378:metabolism; D008969:Molecular Sequence Data; D051839:NFI Transcription Factors; D009707:Nucleosomes / Q000378:metabolism*; D050811:Octamer Transcription Factor-1; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014176:Protein Biosynthesis; D019914:Taq Polymerase; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D051863:Host Cell Factor C1; D051839:NFI Transcription Factors; D009707:Nucleosomes; D050811:Octamer Transcription Factor-1; D009838:Oligodeoxyribonucleotides; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D019914:Taq Polymerase; D004259:DNA-Directed DNA Polymerase; D008836:Micrococcal Nuclease