Conformational Dynamics and the Binding of Specific and Nonspecific DNA by the Autoinhibited Transcription Factor Ets-1
Conformational Dynamics and the Binding of Specific and Nonspecific DNA by the Autoinhibited Transcription Factor Ets-1
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DOI：
10.1021/acs.biochem.6b00460
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发表时间：
2016-07-26
期刊：
影响因子：
2.9
通讯作者：
McIntosh, Lawrence P.
中科院分区：
文献类型：
--
作者：
Desjardins, Genevieve;Okon, Mark;McIntosh, Lawrence P.
Ets-1转录因子对DNA的亲和力被一个内在无序的富含丝氨酸的区域（SRR）和一个附加在其翼螺旋转角螺旋ETS结构域上的螺旋抑制模块（IM）所自动抑制。使用NMR光谱，我们研究了Ets-1如何识别特异性与非特异性DNA，重点是蛋白质动力学和自抑制在这些过程中的作用。在结合任一DNA时，IM的两个边缘稳定的N-末端螺旋主要展开，但仍具有部分有序的构象。此外，在酰胺化学位移扰动映射的基础上，Ets-1通过相同的典型ETS结构域界面与特异性和非特异性DNA相关联。这些相互作用在结构上独立于SRR，因此自抑制不赋予DNA结合特异性。然而，相对于明显的NMR光谱变化Ets-1所造成的特异性DNA结合，光谱的非特异性DNA复合物显示构象交换增宽，缺乏几个诊断酰胺和吲哚信号归因于氢键相互作用，在报道的X-射线晶体结构的转录因子与其同源的DNA序列。这种差异突出了几个界面赖氨酸和精氨酸侧链的化学位移和弛豫特性。总的来说，这些数据支持一个通用模型，其中Ets-1通过动态静电相互作用与非特异性DNA相互作用，而氢键驱动与特定DNA形成有序的复合物。
The affinity of the Ets-1 transcription factor for DNA is autoinhibited by an intrinsically disordered serine-rich region (SRR) and a helical inhibitory module (IM) appended to its winged helix turn helix ETS domain. Using NMR spectroscopy, we investigated how Ets-1 recognizes specific versus nonspecific DNA, with a focus on the roles of protein dynamics and autoinhibition in these processes. Upon binding either DNA, the two marginally stable N-terminal helices of the IM predominantly unfold, but still sample partially ordered conformations. Also, on the basis of amide chemical shift perturbation mapping, Ets-1 associates with both specific and nonspecific DNA through the same canonical ETS domain interface. These interactions are structurally independent of the SRR, and thus autoinhibition does not impart DNA-binding specificity. However, relative to the pronounced NMR spectroscopic changes in Ets-1 resulting from specific DNA binding, the spectra of the nonspecific DNA complexes showed conformational exchange broadening and lacked several diagnostic amide and indole signals attributable to hydrogen bonding interactions seen in reported X-ray crystallographic structures of this transcription factor with its cognate DNA sequences. Such differences are highlighted by the chemical shift and relaxation properties of several interfacial lysine and arginine side chains. Collectively, these data support a general model in which Ets-1 interacts with nonspecific DNA via dynamic electrostatic interactions, whereas hydrogen bonding drives the formation of well-ordered complexes with specific DNA.