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Team Publications
Non Coding RNA, Epigenetic and Genome Fluidity
Year of publication 2009
Marina Pinskaya, Anitha Nair, David Clynes, Antonin Morillon, Jane Mellor (2009 Mar 11)
Nucleosome remodeling and transcriptional repression are distinct functions of
Isw1 in Saccharomyces cerevisiae.
Molecular and cellular biology : 2419-30 : DOI : 10.1128/MCB.01050-08
Summary
The SANT domain is a nucleosome recognition module found in transcriptional regulatory
proteins, including chromatin-modifying enzymes. It shows high functional degeneracy
between species, varying in sequence and copy number. Here, we investigate functions in
vivo associated with two SANT motifs, SANT and SLIDE, in the Saccharomyces cerevisiae
Isw1 chromatin-remodeling ATPase. We show that differences in the primary structures of
the SANT and SLIDE domains in yeast and Drosophila melanogaster reflect their different
functions. In yeast, the SLIDE domain is required for histone interactions, while this is a
function of the SANT domain in flies. In yeast, both motifs are required for optimal
association with chromatin and for formation of the Isw1b complex (Isw1, Ioc2, and Ioc4).
Moreover, nucleosome remodeling at the MET16 locus is defective in strains lacking the
SANT or SLIDE domain. In contrast, the SANT domain is dispensable for the interaction
between Isw1 and Ioc3 in the Isw1a complex. We show that, although defective in
nucleosome remodeling, Isw1 lacking the SANT domain is able to repress transcription
initiation at the MET16 promoter. Thus, chromatin remodeling and transcriptional repression
are distinct activities of Isw1.
Year of publication 2008
Julia Berretta, Marina Pinskaya, Antonin Morillon (2008 Mar 5)
A cryptic unstable transcript mediates transcriptional trans-silencing of the Ty1
retrotransposon in S. cerevisiae.
Genes & development : 615-26 : DOI : 10.1101/gad.458008
Summary
Cryptic unstable transcripts (CUTs) are synthesized from intra- and intergenic regions in
Saccharomyces cerevisiae and are rapidly degraded by RNA surveillance pathways, but their
function(s) remain(s) elusive. Here, we show that an antisense TY1 CUT, starting within the
Ty1 retrotransposon and encompassing the promoter 5′ long terminal repeat (LTR), mediates
RNA-dependent gene silencing and represses Ty1 mobility. We show that the Ty1 regulatory
RNA is synthesized by RNA polymerase II, polyadenylated, and destabilized by the
cytoplasmic 5′ RNA degradation pathway. Moreover, the Ty1 regulatory RNA represses Ty1
transcription and transposition in trans by acting on the de novo transcribed TY1 RNA.
Consistent with a transcriptional regulation mechanism, we show that RNA polymerase II
occupancy is reduced on the Ty1 chromatin upon silencing, although TBP binding remains
unchanged. Furthermore, the Ty1 silencing is partially mediated by histone deacetylation
and requires Set1-dependent histone methylation, pointing out an analogy with
INSTITUT CURIE, 20 rue d’Ulm, 75248 Paris Cedex 05, France | 1
Team Publications
Non Coding RNA, Epigenetic and Genome Fluidity
heterochromatin gene silencing. Our results show the first example of an RNA-dependent
gene trans-silencing mediated by epigenetic marks in S. cerevisiae.
INSTITUT CURIE, 20 rue d’Ulm, 75248 Paris Cedex 05, France | 2