Remodeling of Nucleosome-Dimer
Particles with yIsw2 Promotes Their Association with ALL-1 SET Domain
in Vitro
- Publication date
- Publisher
Abstract
Functioning of histone lysine methyltransferases (HKMTs)
involves interactions of their catalytic domain “SET”
with the N-termini of histone H3. However, these interactions are
restricted in canonical nucleosomes due to the limited accessibility
of H3 termini. Here we investigated whether nucleosome remodeling
with the yeast Isw2 affects nucleosome affinity to the SET domain
of ALL-1 HKMT. Reconstitution of mononucleosomes by salt dilutions
also produces some nucleosome-dimer particles (self-associated mononucleosomes,
described by: Tatchell and van Holde (1977) <i>Biochemistry</i>, <i>16</i>, 5295–5303). The GST-tagged SET-domain
polypeptide of ALL-1 was assayed for binding to assembled mononucleosomes
and nucleosome-dimer particles, either intact or remodeled with purified
yeast Isw2. Remodeling of mononucleosomes does not noticeably affect
their affinity to SET domain; however, yIsw2 remodeling of nucleosome-dimer
particles facilitated their association with GST-SET polypeptide.
Therefore, it is conceivable that nucleosome interactions in trans
could be implicated in the maintenance of chromatin methylation patterns
in vivo