The Retinoblastoma Family of Proteins Directly Represses
Transcription in Saccharomyces cerevisiae*
Milica
Arneri
,
Ana
Traven,
Lidija
Stare
in
i, and
Mary
Sopta§
From the Department of Molecular Genetics, Rudjer
Bokovi Institute, Bijenicka 54, Zagreb, Croatia
The retinoblastoma family of proteins are key
cell cycle regulatory molecules important for the differentiation of
various mammalian cell types. The retinoblastoma protein regulates
transcription of a variety of genes either by blocking the activation
domain of various activators or by active repression via recruitment to
appropriate promoters. We show here that the retinoblastoma family of
proteins functions as direct transcriptional repressors in a
heterologous yeast system when fused to the DNA binding domain of Gal4.
Mapping experiments indicate that either the A or the B domain of the
pocket region is sufficient for repression in vivo. As is
the case in mammalian cells, a phosphorylation site mutant of the
retinoblastoma protein is a stronger transcriptional repressor than the
wild type protein. We show that transcriptional repression by pRb is
dependent on CLN3 in vivo. Furthermore, the yeast histone
deacetylase components, RPD3 and SIN3, are
required for transcriptional repression.
*
This research was supported by a grant (to M. S.) from the
Croatian Ministry of Science and Technology.The costs of publication of this
article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement" in accordance with 18 U.S.C. Section
1734 solely to indicate this fact.
Recipient of a graduate scholarship from the Croatian Ministry of
Science and Technology.
§
To whom correspondence should be addressed. Tel.: 385-1-456-0948l;
Fax: 385-1-456-1177; E-mail: msopta@rudjer.irb.hr.
Copyright © 2002 by The American Society for Biochemistry and Molecular Biology, Inc.
