Nucleosomes can form a polar barrier to transcript elongation by RNA polymerase II.
Nucleosomes uniquely positioned on high-affinity DNA sequences present a polar barrier to transcription by human and yeast RNA polymerase II (Pol II). In one transcriptional orientation, these nucleosomes provide a strong, factor- and salt-insensitive barrier at the entry into the H3/H4 tetramer that can be recapitulated without H2A/H2B dimers. The same nucleosomes transcribed in the opposite orientation form a weaker, more diffuse barrier that is largely relieved by higher salt, TFIIS, or FACT. Barrier properties are therefore dictated by both the local nucleosome structure (influenced by the strength of the histone-DNA interactions) and the location of the high-affinity DNA region within the nucleosome. Pol II transcribes DNA sequences at the entry into the tetramer much less efficiently than the same sequences located distal to the nucleosome dyad. Thus, entry into the tetramer by Pol II facilitates further transcription, perhaps due to partial unfolding of the tetramer from DNA.
Bondarenko
Vladimir A
VA
Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, 675 Hoes Lane, Room 405, Piscataway, New Jersey 08854, USA.
Steele
Louise M
LM
Ujvári
Andrea
A
Gaykalova
Daria A
DA
Kulaeva
Olga I
OI
Polikanov
Yury S
YS
Luse
Donal S
DS
Studitsky
Vasily M
VM
D001483:Base Sequence; D004247:DNA / Q000235:genetics; D019281:Dimerization; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009707:Nucleosomes / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013379:Substrate Specificity; D014158:Transcription, Genetic
D006657:Histones; D009707:Nucleosomes; D012333:RNA, Messenger; D004247:DNA; D012319:RNA Polymerase II