Genome-wide uniformity of human 'open' pre-initiation complexes

Genome Res. 2017 Jan;27(1):15-26. doi: 10.1101/gr.210955.116. Epub 2016 Nov 10.


Transcription of protein-coding and noncoding DNA occurs pervasively throughout the mammalian genome. Their sites of initiation are generally inferred from transcript 5' ends and are thought to be either locally dispersed or focused. How these two modes of initiation relate is unclear. Here, we apply permanganate treatment and chromatin immunoprecipitation (PIP-seq) of initiation factors to identify the precise location of melted DNA separately associated with the preinitiation complex (PIC) and the adjacent paused complex (PC). This approach revealed the two known modes of transcription initiation. However, in contrast to prevailing views, they co-occurred within the same promoter region: initiation originating from a focused PIC, and broad nucleosome-linked initiation. PIP-seq allowed transcriptional orientation of Pol II to be determined, which may be useful near promoters where sufficient sense/anti-sense transcript mapping information is lacking. PIP-seq detected divergently oriented Pol II at both coding and noncoding promoters, as well as at enhancers. Their occupancy levels were not necessarily coupled in the two orientations. DNA sequence and shape analysis of initiation complex sites suggest that both sequence and shape contribute to specificity, but in a context-restricted manner. That is, initiation sites have the locally "best" initiator (INR) sequence and/or shape. These findings reveal a common core to pervasive Pol II initiation throughout the human genome.

Publication types

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

MeSH terms

  • Animals
  • Binding Sites
  • Chromatin / genetics*
  • Chromatin Immunoprecipitation / methods
  • Genome, Human
  • Humans
  • Manganese Compounds / chemistry
  • Oxides / chemistry
  • Promoter Regions, Genetic
  • RNA Polymerase II / genetics
  • Sequence Analysis, DNA
  • Transcription Factors / genetics*
  • Transcription Initiation Site*
  • Transcription, Genetic*


  • Chromatin
  • Manganese Compounds
  • Oxides
  • Transcription Factors
  • permanganic acid
  • RNA Polymerase II