Role of the C-terminal binding protein PXDLS motif binding cleft in protein interactions and transcriptional repression
Role of the C-terminal binding protein PXDLS motif binding cleft in protein interactions and transcriptional repression
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DOI：
10.1128/mcb.00445-06
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发表时间：
2006-11-01
影响因子：
5.3
通讯作者：
Crossley, Merlin
中科院分区：
文献类型：
--
作者：
Quinlan, Kate G. R.;Verger, Alexis;Crossley, Merlin
C端结合蛋白(CtBP)是一种多功能蛋白，可以介导基因抑制。CtBPs含有一个裂隙，可以结合Pro-X-Asp-Leu-Ser(PXDLS)基序。PXDLS基序存在于许多转录因子和基因抑制的效应器中，如某些组蛋白脱乙酰酶。CtBPs被描述为桥梁蛋白，它自结合并连接含PXDLS的转录因子和含PXDLS的染色质修饰酶。CtBP还招募不包含可识别的PXDLS图案的效应器。我们研究了PXDLS结合裂解对CtBP与各种伙伴蛋白相互作用及其抑制转录能力的重要性。我们使用CtBP裂解突变体和裂隙填充的融合衍生物来区分结合在裂隙中和CtBP表面其他地方的伙伴蛋白。功能分析表明，携带有缺陷裂隙的CtBP突变体在与DNA结合结构域融合时仍保持抑制活性。这一结果表明，裂隙并不是招募效应器所必需的。相反，当在没有融合的DNA结合域的情况下进行测试时，裂解的破坏会取消抑制活性。这些结果表明PXDLS结合裂解在功能上是重要的，但表明它是CtBP复合体定位到启动子结合的转录因子所必需的。
C-terminal binding proteins (CtBPs) are multifunctional proteins that can mediate gene repression. CtBPs contain a cleft that binds Pro-X-Asp-Leu-Ser (PXDLS) motifs. PXDLS motifs occur in numerous transcription factors and in effectors of gene repression, such as certain histone deacetylases. CtBPs have been depicted as bridging proteins that self-associate and link PXDLS-containing transcription factors to PXDLS-containing chromatin-modifying enzymes. CtBPs also recruit effectors that do not contain recognizable PXDLS motifs. We have investigated the importance of the PXDLS binding cleft to CtBP's interactions with various partner proteins and to its ability to repress transcription. We used CtBP cleft mutant and cleft-filled fusion derivatives to distinguish between partner proteins that bind in the cleft and elsewhere on the CtBP surface. Functional assays demonstrate that CtBP mutants that carry defective clefts retain repression activity when fused to beterollogous DNA-binding domains. This result suggests that the cleft is not essential for recruiting effectors. In contrast, when tested in the absence of a fused DNA-binding domain, disruption of the cleft abrogates repression activity. These results demonstrate that the PXDLS binding cleft is functionally important but suggest that it is primarily required for localization of the CtBP complex to promoter-bound transcription factors.