The origin recognition complex and Sir4 protein recruit Sir1p to yeast silent chromatin through independent interactions requiring a common Sir1p domain
The origin recognition complex and Sir4 protein recruit Sir1p to yeast silent chromatin through independent interactions requiring a common Sir1p domain
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DOI：
10.1128/mcb.24.2.774-786.2004
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发表时间：
2004-01-01
影响因子：
5.3
通讯作者：
Fox, CA
中科院分区：
文献类型：
--
作者：
Bose, ME;McConnell, KH;Fox, CA
Sir 1 p是使芽殖酵母酿酒酵母（Saccharomycescerevisiae）中隐蔽交配型位点HMRa沉默所需的四种SIR（沉默信息调节子）蛋白之一。Sir 1 p与orc 1 p（origin recognition complex，ORC）的最大亚基）的相互作用对于Sir 1 p结合HMRa的能力和沉默染色质形成的功能至关重要。在这里，我们表明，在Sir 1 p，ORC相互作用区域（OIR），一个离散的结构域，是必要的和足够的Sir 1 p-ORC相互作用。OIR包含最初定义的沉默子缺失缺陷区以及额外的氨基酸。此外，Sir 1 p-Sir 4p相互作用需要更大的Sir 1 p区域，其中包括OIR。氨基酸取代导致Sir 1 p-Orc 1 p或Sir 1 p-Sir 4p相互作用的缺陷减少了HMRa沉默和Sir 1 p与染色质中HMRa的结合。这些数据支持一种模型，其中Sir 1 p与HMRa的关联是由需要共同Sir 1 p结构域的可分离的Sir 1 p-ORC和Sir 1 p-Sir 4p相互作用介导的，并且它们表明Sir 1 p-ORC相互作用至少部分地通过与Sir 4p的相互作用而限于沉默剂。
Sir1p is one of four SIR (silent information regulator) proteins required for silencing the cryptic mating-type locus HMRa in the budding yeast Saccharomyces cerevisiae. A Sir1p interaction with Orc1p, the largest subunit of the origin recognition complex (ORC), is critical for Sir1p's ability to bind HMRa and function in the formation of silent chromatin. Here we show that a discrete domain within Sir1p, the ORC interaction region (OIR), was necessary and sufficient for a Sir1p-ORC interaction. The OIR contains the originally defined silencer recognition-defective region as well as additional amino acids. In addition, a Sir1p-Sir4p interaction required a larger region of Sir1p that included the OIR. Amino acid substitutions causing defects in either a Sir1p-Orc1p or a Sir1p-Sir4p interaction reduced HMRa silencing and Sir1p binding to HMRa in chromatin. These data support a model in which Sir1p's association with HMRa is mediated by separable Sir1p-ORC and Sir1p-Sir4p interactions requiring a common Sir1p domain, and they indicate that a Sir1p-ORC interaction is restricted to silencers, at least in part, through interactions with Sir4p.