title: Transcription complex disruption caused by a transition in chromatin structure.
abstract: Chromatin structure is known to influence class III gene expression in vitro. We describe the active transcription of Xenopus class III genes following replication and assembly into chromatin by using Xenopus egg extracts. Changes in the structure of this active chromatin dependent on the presence of exogeneous Mg2+ ATP or on the addition of a mixture of histones H2A and H2B are shown to lead to the selective repression of Xenopus 5S RNA genes. Preexisting transcription complexes on 5S DNA are disrupted following the reorganization of a "disordered" histone-DNA complex into a structure consisting of physiologically spaced nucleosomes. Thus, we demonstrate that chromatin structural transitions can have dominant and specific effects on transcription.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.
authors.forename: G
authors.initials: G
authors.lastname: Almouzni
authors.forename: M
authors.initials: M
authors.lastname: Méchali
authors.forename: A P
authors.initials: AP
authors.lastname: Wolffe
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000502:physiology; D002843:Chromatin / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure*; D004275:DNA, Ribosomal / Q000235:genetics*; D005260:Female; D006657:Histones / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology* / Q000502:physiology; D012341:RNA, Ribosomal, 5S / Q000235:genetics; D035582:Transcription Factor TFIIIA; D035361:Transcription Factor TFIIIB; D014157:Transcription Factors / Q000378:metabolism; D019474:Transcription Factors, TFIII; D014158:Transcription, Genetic / Q000187:drug effects; D014982:Xenopus laevis; D000098832:Transcription Factor TFIIIC
chemical_list: D002843:Chromatin; D004275:DNA, Ribosomal; D006657:Histones; D012341:RNA, Ribosomal, 5S; D035582:Transcription Factor TFIIIA; D035361:Transcription Factor TFIIIB; D014157:Transcription Factors; D019474:Transcription Factors, TFIII; D000098832:Transcription Factor TFIIIC; D000255:Adenosine Triphosphate; D008274:Magnesium