Relaxed Chromatin Formation and Weak Suppression of Homologous Pairing by the Testis-Specific Linker Histone H1T

Biochemistry. 2016 Feb 2;55(4):637-46. doi: 10.1021/acs.biochem.5b01126. Epub 2016 Jan 22.

Abstract

Linker histones bind to nucleosomes and compact polynucleosomes into a higher-order chromatin configuration. Somatic and germ cell-specific linker histone subtypes have been identified and may have distinct functions. In this study, we reconstituted polynucleosomes containing human histones H1.2 and H1T, as representative somatic and germ cell-specific linker histones, respectively, and found that H1T forms less compacted chromatin, as compared to H1.2. An in vitro homologous pairing assay revealed that H1T weakly inhibited RAD51/RAD54-mediated homologous pairing in chromatin, although the somatic H1 subtypes, H1.0, H1.1, H1.2, H1.3, H1.4, and H1.5, substantially suppressed it. An in vivo recombination assay revealed that H1T overproduction minimally affected the recombination frequency, but significant suppression was observed when H1.2 was overproduced in human cells. These results suggested that the testis-specific linker histone, H1T, possesses a specific function to produce the chromatin architecture required for proper chromosome regulation, such as homologous recombination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • DNA Helicases / chemistry*
  • DNA Helicases / genetics
  • DNA Helicases / metabolism
  • DNA-Binding Proteins
  • Histones / chemistry*
  • Histones / genetics
  • Histones / immunology
  • Humans
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Nucleosomes / chemistry*
  • Nucleosomes / genetics
  • Nucleosomes / metabolism
  • Rad51 Recombinase / chemistry*
  • Rad51 Recombinase / genetics
  • Rad51 Recombinase / metabolism
  • Recombination, Genetic*

Substances

  • DNA-Binding Proteins
  • Histones
  • Nuclear Proteins
  • Nucleosomes
  • RAD51 protein, human
  • Rad51 Recombinase
  • DNA Helicases
  • RAD54L protein, human