SAR-dependent mobilization of histone H1 by HMG-I/Y in vitro: HMG-I/Y is enriched in H1-depleted chromatin

EMBO J. 1993 Aug;12(8):3237-47. doi: 10.1002/j.1460-2075.1993.tb05993.x.

Abstract

An experimental assay was developed to search for proteins capable of antagonizing histone H1-mediated general repression of transcription. T7 RNA polymerase templates containing an upstream scaffold-associated region (SAR) were highly selectively repressed by H1 relative to non-SAR control templates. This is due to the nucleation of H1 assembly into flanking DNA brought about by the numerous A-tracts (AT-rich sequences containing short homopolymeric runs of dA.dT base pairs) of the SAR. Partial, selective titration of these A-tracts by the high mobility group (HMG) protein HMG-I/Y led to the complete derepression of transcription from the SAR template by inducing the redistribution of H1 on to non-SAR templates. SARs are associated with many highly transcribed regulated genes where they may serve to facilitate the HMG-I/Y-mediated displacement of histone H1 in chromatin. Indeed, HMG-I/Y was found to be strongly enriched in the H1-depleted subfraction which can be isolated from chromatin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Chromatin / metabolism*
  • DNA / metabolism*
  • DNA-Directed RNA Polymerases / metabolism
  • High Mobility Group Proteins / metabolism*
  • Histones / antagonists & inhibitors
  • Histones / metabolism*
  • Molecular Sequence Data
  • Rats
  • Templates, Genetic
  • Transcription, Genetic
  • Viral Proteins

Substances

  • Chromatin
  • High Mobility Group Proteins
  • Histones
  • Viral Proteins
  • DNA
  • bacteriophage T7 RNA polymerase
  • DNA-Directed RNA Polymerases