1 research outputs found
The Effects of Histone H2B Ubiquitylations on the Nucleosome Structure and Internucleosomal Interactions
Eukaryotic gene compaction takes place at multiple levels
to package
DNA to chromatin and chromosomes. Two of the most fundamental levels
of DNA packaging are at the nucleosome and dinucleosome stacks. The
nucleosome is the basic gene-packing unit and is composed of DNA wrapped
around a histone core. Nucleosomes stack with one another for further
compaction of DNA. The first stacking step leads to dinucleosome formation,
which is driven by internucleosomal interactions between various parts
of two nucleosomes. Histone proteins are rich targets for post-translational
modifications, some of which affect the structure of the nucleosome
and the interactions between nucleosomes. These effects are often
implicated in the regulation of various genomic transactions. In particular,
histone H2B ubiquitylation has been associated with facilitated transcription
and hexasome formation. Here, we employed semi-synthetically ubiquitylated
histone H2B and single-molecule FRET to investigate the effects of
H2B ubiquitylations at lysine 34 (H2BK34) and lysine 120 (H2BK120)
on the structure of the nucleosome and the interactions between two
nucleosomes. Our results suggest that H2BK34 ubiquitylation widens
the DNA gyre gap in the nucleosome and stabilizes long- and short-range
internucleosomal interactions while H2BK120 ubiquitylation does not
affect the nucleosome structure or internucleosomal interactions.
These results suggest potential roles for H2B ubiquitylations in facilitated
transcription and hexasome formation while maintaining the structural
integrity of chromatin