Histone occupancy in vivo at the 601 nucleosome binding element is determined by transcriptional history

Mol Cell Biol. 2011 Aug;31(16):3485-96. doi: 10.1128/MCB.05599-11. Epub 2011 Jun 20.

Abstract

We report in vivo analysis of histone and RNA polymerase II (pol II) occupancy at the 601 element, which functions as a strong in vitro nucleosome-positioning element and transcriptional pause site. Surprisingly, nucleosomes were not strongly positioned over the 601 element inserted either within a yeast chromosomal open reading frame (ORF) (GAL1-YLR454W) or in an intergenic region. In fact 601 within GAL1-YLR454W was actually depleted of histones relative to flanking sequences and did not cause pol II pausing. Upstream of an inserted 601 element within GAL1-YLR454W, a positioned nucleosome was formed whose location depended on transcriptional history; it shifted after a round of activation and repression. Transcriptional activation caused histone eviction throughout the GAL1-YLR454W ORF, except at 601, where there was no loss and some net histone deposition. In contrast, a second round of activation after glucose shutoff caused histone eviction both at 601 and elsewhere in the ORF. We conclude that the intrinsic high-affinity histone-DNA interactions at 601 do not necessarily play a dominant role in establishing nucleosomes or pol II pause sites within a coding region in vivo and that transcriptional history can have an important influence on histone occupancy flanking this sequence.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Chromatin Assembly and Disassembly
  • Fungal Proteins
  • Histones / metabolism*
  • Nucleosomes / metabolism*
  • RNA Polymerase II / metabolism*
  • Transcription, Genetic*
  • Yeasts / genetics*

Substances

  • Fungal Proteins
  • Histones
  • Nucleosomes
  • RNA Polymerase II