Protein-induced fit: The CRP activator protein changes sequence-specific DNA recognition by the CytR repressor, a highly flexible Lacl member
Protein-induced fit: The CRP activator protein changes sequence-specific DNA recognition by the CytR repressor, a highly flexible Lacl member
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DOI：
10.1093/emboj/16.8.2108
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发表时间：
1997-04-15
期刊：
影响因子：
11.4
通讯作者：
ValentinHansen, P
中科院分区：
文献类型：
--
作者：
Pedersen, H;ValentinHansen, P
CyTR抑制剂和CAMP受体蛋白（CRP）与大肠杆菌中的几个启动子结合以抑制转录起始，协同结合是由两个调节剂之间的蛋白质 - 蛋白质相互作用介导的，此处，这里使用了体外选择实验。 Cytr的DNA结合特性本身以及与CAMP-CRP共同结合时。我们表明，最佳的Cytr结合位点由直接或倒置方向的两个八聚体重复组成，并以2 bp的形式组成。但是，当与CAMP-CRP共同结合时，Cytr识别出以10-13 bp分离的倒重复序列，或者直接重复分离为1 bp。后一组运算符的配置与自然cytr靶标的配置很好地相关，因此，CAMP-CRP诱导Cytr的构象变化，因此阻遏物适合自然目标，最引人注目的是，CYTR可以采用广泛不同的构型，这些构型同样受到青睐。充满活力，用于与CAMP-CRP的复杂形成。我们建议，这种结构适应性对于CYTR抑制具有不同体系结构的启动子至关重要，我们在CRP/CYTR调节系统的背景下讨论了这些新颖的概念，以及对多蛋白-DNA复合形成的结构和功能含义。
The CytR repressor and the cAMP receptor protein (CRP) bind cooperatively to several promoters in Escherichia coli to repress transcription initiation, The synergistic binding is mediated by protein-protein interactions between the two regulators, Here, in vitro selection experiments have been used to examine the DNA-binding characteristics of CytR, by itself and when co-binding with cAMP-CRP. We show that the optimal CytR-binding site consists of two octamer repeats, in direct or inverted orientation, and separated by 2 bp. However, when co-binding with cAMP-CRP, CytR instead recognizes inverted repeats separated by 10-13 bp, or direct repeats separated by 1 bp. The configurations of the latter set of operators correlate well with the configurations of natural CytR targets, Thus, cAMP-CRP induces conformational changes in CytR so that the repressor fits the natural targets, Most strikingly, CytR can adopt widely different conformations that are equally favored energetically for complex formation with cAMP-CRP. We propose that this structural adaptability is essential for CytR repression of promoters with diverse architectures, We discuss these novel concepts in the context of the CRP/CytR regulatory system, as well as the structural and functional implications for multiprotein-DNA complex formation in general.