Nocentini S, Coin F, Saijo M, Tanaka K, Egly J M
CNRS UMR 218 et LRC no. 1 du CEA, Institut Curie, Section de Recherche, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
J Biol Chem. 1997 Sep 12;272(37):22991-4. doi: 10.1074/jbc.272.37.22991.
The human basal transcription factor IIH (TFIIH) is an essential component of the nucleotide excision repair machinery. TFIIH is required for reaction steps concomitant with or prior to the formation of dual incisions in the damaged DNA strand. To understand the mechanism underlying the recruitment of TFIIH to DNA damage sites we have analyzed i) the direct affinity of TFIIH for damaged or undamaged DNA and ii) the interaction of TFIIH with XPA.DNA complexes, formed using unirradiated or UV-irradiated DNA. Filter binding assays showed that TFIIH has some affinity for the DNA, but in contrast to XPA, does not show any preference for UV-irradiated DNA. Pull-down experiments demonstrated that TFIIH binds to XPA.DNA complexes in an UV damage-dependent manner by a direct protein-protein interaction with XPA. We propose that an enhancement of the affinity of XPA protein for TFIIH could arise from conformational changes of XPA when it binds to UV lesions on the DNA.
人类基础转录因子IIH（TFIIH）是核苷酸切除修复机制的重要组成部分。TFIIH是在受损DNA链上形成双切口的同时或之前的反应步骤所必需的。为了了解TFIIH募集到DNA损伤位点的潜在机制，我们分析了：i）TFIIH对受损或未受损DNA的直接亲和力；ii）TFIIH与使用未辐照或紫外线辐照DNA形成的XPA-DNA复合物的相互作用。滤膜结合试验表明，TFIIH对DNA有一定亲和力，但与XPA不同，它对紫外线辐照的DNA没有任何偏好。下拉实验表明，TFIIH通过与XPA的直接蛋白质-蛋白质相互作用，以紫外线损伤依赖的方式与XPA-DNA复合物结合。我们提出，当XPA与DNA上的紫外线损伤结合时，其构象变化可能会增强XPA蛋白对TFIIH的亲和力。
