ASSEMBLY OF THE ARC REPRESSOR OPERATOR COMPLEX - COOPERATIVE INTERACTIONS BETWEEN DNA-BOUND DIMERS
ASSEMBLY OF THE ARC REPRESSOR OPERATOR COMPLEX - COOPERATIVE INTERACTIONS BETWEEN DNA-BOUND DIMERS
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DOI：
10.1021/bi00056a022
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发表时间：
1993-02-09
期刊：
影响因子：
2.9
通讯作者：
SAUER, RT
中科院分区：
文献类型：
--
作者：
BROWN, BM;SAUER, RT
Arc阻遏蛋白是DNA结合蛋白β-ribbon家族的成员，以四聚体的形式与其21个碱基对的操纵子结合。在这里，弧二聚体被示出为特异性地结合到DNA片段包含运营商半位点，并确定这些反应的平衡和动力学常数。DNA结合的二聚体也被证明是短暂的中间体在协会的实验，表明装配的弧四聚体运营商复杂的二聚体发生操作员半网站的顺序添加。当左或右操纵基因半位点被Arc二聚体占据时，协同相互作用使第二个二聚体的亲和力增加约5900倍[Δ DELTAG = -5.1（+/-0.5）kcal/mol]。这种亲和力的增加主要是由复合物半衰期的增加引起的;“非协同”结合的二聚体以几秒的半衰期解离，而“协同”结合的二聚体的半衰期超过1小时。
Arc repressor, a member of the beta-ribbon family of DNA binding proteins, binds to its 21-base-pair operator as a tetramer. Here, the Arc dimer is shown to bind specifically to DNA fragments containing operator half-sites, and the equilibrium and kinetic constants for these reactions are determined. DNA-bound dimers are also shown to be transient intermediates in association experiments, indicating that assembly of the Arc tetramer-operator complex occurs by sequential addition of dimers to operator half-sites. When the left or right operator half-site is occupied by an Arc dimer, cooperative interactions increase the affinity of the second dimer by approximately 5900-fold [DELTADELTAG = -5.1 (+/-0.5) kcal/mol]. This increase in affinity is largely caused by an increase in the half-life of the complex; ''non-cooperatively'' bound dimers dissociate with a half-life of a few seconds while ''cooperatively'' bound dimers have half-lives of more than 1 h.