Silent chromatin in yeast: an orchestrated medley featuring Sir3p [corrected].
Extensive regions of chromosomes can be transcriptionally repressed through silencing mechanisms mediated by complex chromatin structures. One of the most refined molecular portraits of silenced chromatin comes from studies of the silent mating-type loci and telomeres of S. cerevisiae. In this budding yeast, the Sir3p silent information regulator emerges as a critically important silencing component that interacts with nucleosomes and other silencing proteins. Not only is it essential for silencing, but Sir3p is also capable of spreading silenced chromatin when its dosage is increased. Sir3p is a target of mitogen-activated protein (MAP) kinase cascade regulation and has significant similarity to the Orc1p subunit of the DNA replication origin recognition complex. Thus, in concert with other silencing proteins, Sir3p appears poised to respond to cellular signals and reprogram silencing through replication-associated assembly of repressive chromatin structures.
Stone
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EM
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder 80309-0347, USA.
Pillus
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D002843:Chromatin / Q000235:genetics; D004261:DNA Replication; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D016615:Telomere / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism
D002843:Chromatin; D005656:Fungal Proteins; C084122:SIR3 protein, S cerevisiae; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D015534:Trans-Activators