MAL and ternary complex factor use different mechanisms to contact a common surface on the serum response factor DNA-binding domain
MAL and ternary complex factor use different mechanisms to contact a common surface on the serum response factor DNA-binding domain
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DOI：
10.1128/mcb.01902-05
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发表时间：
2006-06-01
影响因子：
5.3
通讯作者：
Treisman, Richard
中科院分区：
文献类型：
--
作者：
Zaromytidou, Alexia-Ileana;Miralles, Francesc;Treisman, Richard
转录因子血清反应因子（SRF）通过其DNA结合结构域与其辅因子MAL/MKL 1相互作用，MAL/MKL 1是心肌蛋白相关转录因子（MRTF）家族的成员。我们定义了一个保守的MAL B1区域内的7个残基序列的复杂的形成所必需的和足够的。相邻的Q盒序列促进了这种相互作用。B1和Q-box区域也对MAL核输入具有拮抗作用，但所涉及的残基在很大程度上是不同的。MAL和SRF辅因子的三元复合因子（TCF）家族;与SRF DNA结合结构域上的疏水沟和口袋相互作用。然而，与TCF不同的是，MAL与SRF的相互作用受到SRF α I-hellix突变的损害，SRF α I-hellix突变减少了SRF-DNA复合物中的DNA弯曲。成簇的SRF α I-螺旋突变强烈损害MAL-SRF复合物的形成，但不影响MAL-SRF复合物中的DNA畸变。DNA结合促进MAL-SRF复合物的形成。DNA酶I足迹法表明，在SRF-MAL复合物中，MAL直接接触DNA。在凝胶迁移率变动分析中，这些接触是有效的MAL-SRF复合物形成所必需的，它们与被SRF保护而不受DNA酶I影响的DNA序列相连接。我们提出了一个MAL-SRF复合物形成的模型，其中MAL通过向SRF DNA结合结构域P-折叠区添加β链与SRF相互作用，而SRF诱导的DNA弯曲促进MAL-DNA接触。
The transcription factor serum response factor (SRF) interacts with its cofactor, MAL/MKL1, a member of the myocardin-related transcription factor (MRTF) family, through its DNA-binding domain. We define a seven-residue sequence within the conserved MAL B1 region essential and sufficient for complex formation. The neighboring Q-box sequence facilitates this interaction. The B1 and Q-box regions also have antagonistic effects on MAL nuclear import, but the residues involved are largely distinct. Both MAL and the ternary complex factor (TCF) family of SRF cofactors; interact with a hydrophobic groove and pocket on the SRF DNA-binding domain. Unlike the TCFs, however, interaction of MAL with SRF is impaired by SRF alpha I-hellix mutations that reduce DNA bending in the SRF-DNA complex. A clustered SRF alpha I-helix mutation strongly impairs MAL-SRF complex formation but does not affect DNA distortion in the MAL-SRF complex. MAL-SRF complex formation is facilitated by DNA binding. DNase I footprinting indicates that in the SRF-MAL complex MAL directly contacts DNA. These contacts, which Hank the DNA sequences protected from DNase I by SRF, are required for effective MAL-SRF complex formation in gel mobility shift assays. We propose a model of MAL-SRF complex formation in which MAL interacts with SRF by the addition of a beta-strand to the SRF DNA-binding domain P-sheet region, while SRF-induced DNA bending facilitates MAL-DNA contact.