Evidence for ORC-dependent repression of budding yeast genes induced by starvation and other stresses

Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
FEMS Yeast Research (Impact Factor: 2.82). 09/2006; 6(5):763-76. DOI: 10.1111/j.1567-1364.2006.00077.x
Source: PubMed


The highly conserved origin recognition complex (ORC) is required for repressing genes in the silent mating type loci of budding yeast. Here we report that at a non-permissive temperature, the temperature-sensitive orc2-1 mutation induces the expression of more than 500 genes, the majority of which are also induced during starvation of wild-type cells. Many genes induced by starvation or by the orc2-1 mutation are also induced by inactivation of proteins required for chromatin-mediated repression of transcription. Genes induced by the orc2-1 mutation, starvation, or inactivation of repressor proteins, map near ORC-binding loci significantly more frequently compared to all genes. Genes repressed by starvation map near ORC-binding sites less frequently compared to all genes, which suggests they have been evolutionarily excluded from regions of repressive chromatin near ORC-binding sites. Deletion of sequences containing ORC-binding sites near the DAL2 and DAL4 genes in the DAL gene cluster, which are induced by either the orc2-1 mutation or by starvation, constitutively activates these genes and abolishes their activation by the orc2-1 mutation. Our findings suggest a role for ORC in the repression of a large number of budding yeast genes induced by starvation or other aspects of a deleterious environment.

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Available from: Ping Liang, Oct 14, 2014
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    • "On the other hand, Orc2p is a subunit of the origin recognition complex (ORC) that functions in pre-replication complex formation [29] and in chromatin silencing at telomere [16]. Interestingly, Orc2p also functions in the transcriptional regulation of stress-responsive genes, acting as a repressor [30,31] or an activator able to induce expression of highly transcribed genes positioned nearby ORCs [15]. Nevertheless, more work is needed to establish the functional connections between overexpression of CAF16 and ORC2 and ion and freeze tolerance in high-sucrose dough. "
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