Abstracts (poster) - Wissenschaft Online

Annette Scharf, Karin Meier, Volker Seitz, Alexander Brehm, Axel Imhof
Kinetics of histone modifications during in vitro chromatin
assembly
Histone modifications play a crucial role in the establishment and maintenance of gene
expression patterns. In order to faithfully maintain a particular set of modifications,
mechanisms must exist that allow the modification of the newly deposited histones
according to the pre-existing pattern. In order to analyse the changes of histone
modifications during chromatin assembly and maturation, we used an in vitro chromatin
assembly system from Drosophila embryo extracts. In accordance with what has been
observed in vivo, we find a deacetylation of the initially diacetylated isoform of histone
H4, which is dependent on chromatin assembly. Immediately after deposition of the
histones onto DNA H4 is monomethylated at K20, which is required for an efficient
deacetylation of the H4 molecule. K20 methylation dependent l(3)MBT association with
chromatin and the identification of a l(3)MBT-dRPD3 complex suggest that a deacetylase
is specifically recruited to the monomethylated substrate through interaction with
l(3)MBT. Moreover, the monomethylation of K20 also facilitates the release of members
of the chromatin assembly factor CAF1 from the newly assembled chromatin. Our data
suggest that an ordered appearance and disappearance of histone modification marks
occurs at newly assembled chromatin and regulates the maturation of chromatin.
contact:
Annette Scharf
Ludwig Maximilians Universität
Adolf Butenandt Institut
annette.scharf@med.uni-muenchen.de
Schillerstrasse 44
80336 München (Germany)