Open AccessExpanded Roles of the Origin Recognition Complex in the Architecture and Function of Silenced Chromatin in Saccharomyces cerevisiae
Author(s) -
Bilge Özaydın,
Jasper Rine
Publication year - 2010
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.00614-09
Subject(s) - biology , chromatin , saccharomyces cerevisiae , genetics , gene silencing , chromatin immunoprecipitation , origin recognition complex , dna replication , microbiology and biotechnology , dna , gene , eukaryotic dna replication , gene expression , promoter
The silenced chromatin at the cryptic mating-type loci (HML andHMR ) ofSaccharomyces cerevisiae requires a cell cycle event between early S phase and G2 /M phase to achieve repression. Although DNA replicationper se is not essential for silencing, mutations in many of the proteins involved in DNA replication affect silencing. Each of the four silencers, which flank the silenced loci, includes an origin recognition complex (ORC) binding site (ACS ). ORC directly interacted with Sir1 and recruits Sir1 to the silencers. This study describes additional roles for ORC in the architecture of silenced chromatin. Using chromatin immunoprecipitation (ChIP) analysis, we found that ORC physically interacts throughout the internal regions ofHMR as well as with silencers. This interaction depended on the presence of Sir proteins and, in part, on theHMR-I silencer. ORC remained associated with the internal regions ofHMR even when these regions were recombinationally separated from the silencers. Moreover, ORC could be recruited to the silencers lacking anACS through its Sir1 interaction.