title: [Molecular mechanisms of transcription through a nuclesome by RNA polymerase II].
abstract: The Pol II-type mechanism is conserved from yeast to human. After initiation of transcription, Pol II can be paused within the early transcribed region of a gene. Then Pol II overcomes the initial nucleosomal barrier, and efficiently proceeds through chromatin. At low- to moderate-level transcription progression of Pol II is characterized by displacement/exchange of only H2A/H2B dimer(s) and hexasome survival, likely mediated through formation of small intranucleosomal DNA loops. This mechanism helps to preserve the "histone" code during transcription. As the transcription rate is increased, the distance between transcribing Pol II complexes becomes shorter, and trailing Pol II complexes may encounter the hexasome formed after previous transcription round, before the H2A/H2B dimer re-binds to the hexasome. In this case an unstable intermediate with a smaller number of DNA-histone contacts is formed, resulting in eviction of the histone hexamer from DNA in vitro; therefore here all core histones are evicted/exchanged in vivo. Various protein factors and histone chaperones are involved in chromatin transcription by Pol II in vivo.
authors.forename: O I
authors.initials: OI
authors.lastname: Kulaeva
authors.forename: N V
authors.initials: NV
authors.lastname: Maliuchenko
authors.forename: D V
authors.initials: DV
authors.lastname: Nikitin
authors.forename: A V
authors.initials: AV
authors.lastname: Demidenko
authors.forename: O V
authors.initials: OV
authors.lastname: Chertkov
authors.forename: N S
authors.initials: NS
authors.lastname: Efimova
authors.forename: M P
authors.initials: MP
authors.lastname: Kirpichnikov
authors.forename: V M
authors.initials: VM
authors.lastname: Studitskiĭ
mesh_terms: D002467:Cell Nucleus / Q000235:genetics; D002843:Chromatin / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D006609:High Mobility Group Proteins / Q000235:genetics; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009707:Nucleosomes / Q000235:genetics; D012319:RNA Polymerase II / Q000235:genetics*; D061805:Transcription Elongation, Genetic; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors / Q000235:genetics
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D006657:Histones; D009707:Nucleosomes; C073537:SSRP1 protein, human; D035602:Transcriptional Elongation Factors; D012319:RNA Polymerase II