首页> 美国卫生研究院文献>Nucleic Acids Research >Structures of carbon catabolite protein A–(HPr-Ser46-P) bound to diverse catabolite response element sites reveal the basis for high-affinity binding to degenerate DNA operators
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Structures of carbon catabolite protein A–(HPr-Ser46-P) bound to diverse catabolite response element sites reveal the basis for high-affinity binding to degenerate DNA operators

机译:碳分解代谢蛋白A–(HPr-Ser46-P)的结构与多种分解代谢反应元件位点结合揭示了高亲和力结合可降解简并DNA操作员的基础

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摘要

In Gram-positive bacteria, carbon catabolite protein A (CcpA) is the master regulator of carbon catabolite control, which ensures optimal energy usage under diverse conditions. Unlike other LacI-GalR proteins, CcpA is activated for DNA binding by first forming a complex with the phosphoprotein HPr-Ser46-P. Bacillus subtilis CcpA functions as both a transcription repressor and activator and binds to more than 50 operators called catabolite response elements (cres). These sites are highly degenerate with the consensus, WTGNNARCGNWWWCAW. How CcpA–(HPr-Ser46-P) binds such diverse sequences is unclear. To gain insight into this question, we solved the structures of the CcpA–(HPr-Ser46-P) complex bound to three different operators, the synthetic (syn) cre, ackA2 cre and gntR-down cre. Strikingly, the structures show that the CcpA-bound operators display different bend angles, ranging from 31° to 56°. These differences are accommodated by a flexible linkage between the CcpA helix-turn-helix-loop-helix motif and hinge helices, which allows independent docking of these DNA-binding modules. This flexibility coupled with an abundance of non-polar residues capable of non-specific nucleobase interactions permits CcpA–(HPr-Ser46-P) to bind diverse operators. Indeed, biochemical data show that CcpA–(HPr-Ser46-P) binds the three cre sites with similar affinities. Thus, the data reveal properties that license this protein to function as a global transcription regulator.
机译:在革兰氏阳性细菌中,碳分解代谢物蛋白A(CcpA)是碳分解代谢物控制的主要调节剂,可确保在各种条件下实现最佳能源利用。与其他LacI-GalR蛋白不同,CcpA通过首先与磷蛋白HPr-Ser46-P形成复合物而被激活以结合DNA。枯草芽孢杆菌CcpA既是转录抑制子又是激活子,并与50多种称为分解代谢物响应元件(cres)的操纵子结合。根据共识,WTGNNARCGNWWWCAW使这些站点高度退化。 CcpA–(HPr-Ser46-P)如何结合这样多种序列尚不清楚。为了深入了解这个问题,我们解决了绑定到三个不同算子的CcpA-(HPr-Ser46-P)复合物的结构,即合成(syn)cre,ackA2 cre和gntR-down cre。令人惊讶的是,这些结构表明与CcpA结合的操纵子显示出不同的弯曲角度,范围从31°到56°。这些差异可通过CcpA螺旋-转-螺旋-环-螺旋基序和铰链螺旋之间的灵活连接来解决,这允许这些DNA结合模块独立对接。这种灵活性加上能够进行非特异性核碱基相互作用的大量非极性残基,使得CcpA–(HPr-Ser46-P)可以结合各种操纵子。实际上,生化数据表明,CcpA–(HPr-Ser46-P)以相似的亲和力结合了三个Cre位点。因此,数据揭示了许可该蛋白质充当全局转录调节剂的特性。

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