Basic linker of macroH2A stabilizes DNA at the entry/exit site of the nucleosome
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Date
2012-06-29Author
Chakravarthy, Srinivas
Patel, Ashok
Bowman, Gregory D.
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Show full item recordAbstract
MacroH2A is a histone H2A variant that is typically
found in heterochromatic regions of the genome.
A positively charged linker that connects the
histone-fold with the macro-domain was suggested
to have DNA-binding properties, and has been
shown to promote oligomerization of chromatin
fibers. Here we examine the influence of this basic
linker on DNA of mononucleosomes. We find that
the macro-linker reduces accessibility to extranucleosomal
DNA, and appears to increase compaction
of the nucleosome. These properties arise
from interactions between the H1-like basic linker
region and DNA around the entry/exit site, which
increases protection of nucleosomal DNA from exonuclease
III digestion by 10 bp. By stabilizing the
wrapping of DNA around the histone core, this basic
linker of macroH2A may alter the distribution of
nucleosome-associated factors, and potentially
contribute to the more compacted nature of
heterochromatin.