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Archives of Industrial Biotechnology | Volume 2
May 14-15, 2018 | Montreal, Canada
World Yeast Congress
T
he transmission of epigenetic marks on histones and DNA
is an integral part of eukaryotic DNA replication. This
transmission culminates in the reconstitution of pre-existing
chromatin structures or, alternatively, in an epigenetic
conversion of the replicated locus. The subtelomeric genes
of
S. cerevsiae
can be active or “silenced” and infrequently
alternated between these two states. This phenomenon
is referred to as Telomere Position Effect (TPE). The active
or silenced states are determined by chromatin structures,
which resemble euchromatin and heterochromatin in
metazoans. We have a good understanding of the processes
that establish and maintain these chromatin structures, but
have very superficial understanding of the processes that
lead to a conversion of the epigenetic state of these genes.
Recently, we have developed an assay for the quantitative
assessment of the frequency of epigenetic conversions at
the telomeres of S. cerevisiae. We have documented that
the destruction of Chromatin Assembly Factor-1 (CAF-1) or
the helicase
RRM3
substantially reduce the frequency of
conversions. CAF-I is a histone chaperone, which reassembles
nucleosomes after the passage of the replication forks.
RRM3 encodes a DNA helicase that helps the resumption of
replication of paused replication forks. Of note, subtelomeric
DNA contains multiple RRM3-dependent replication pausing
sites. Current models suggest that both Rrm3p and CAF-1
are recruited to replication forks via an interaction with the
Proliferating Cell Nuclear Antigen (PCNA, POL30) and that
this interaction is regulated by the DBF4-Dependent Kinase,
DDK. In this presentation, we propose to use TPE as model
for replication-coupled epigenetic conversions. We will
present our recent studies on the role of two kinases that
phosphorylate (CDK and DDK) on the stability and activity of
CAF-I.
Speaker Biography
Krassimir Yankulov has completed his PhD from the Imperial Cancer Research Fund,
London, England in 1994 and also completed his Post-doc at the Amgen Institute,
Toronto, Canada. Since 1998, he is a Professor at the Department of Molecular and
Cellular Biology at the University of Guelph in Canada, Ontario. His main focus of
research is on epigenetics in yeast. He has published over 40 publications that have
been cited over 2000 times. He is serving as an Editorial Board Member of
Frontiers
in
Genetics
and of
PLoS One.
e:
yankulov@uoguelph.caTelomere position effect epigenetic conversions and paused replication forks
Krassimir Yankulov, Hollie Rowlands, Ririththiv Dhavarasa
and
Ashley Chen
University of Guelph, Canada