Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, USA.
Biophys J. 2010 Jul 7;99(1):248-56. doi: 10.1016/j.bpj.2010.04.010.
Over the past decade, microRNAs (miRNAs) have been shown to affect gene regulation by basepairing with messenger RNA, and their misregulation has been directly linked with cancer. DGCR8, a protein that contains two dsRNA-binding domains (dsRBDs) in tandem, is vital for nuclear maturation of primary miRNAs (pri-miRNAs) in connection with the RNase III enzyme Drosha. The crystal structure of the DGCR8 Core (493-720) shows a unique, well-ordered structure of the linker region between the two dsRBDs that differs from the flexible linker connecting the two dsRBDs in the antiviral response protein, PKR. To better understand the interfacial interactions between the two dsRBDs, we ran extensive MD simulations of isolated dsRBDs (505-583 and 614-691) and the Core. The simulations reveal correlated reorientations of the two domains relative to one another, with the well-ordered linker and C-terminus serving as a pivot. The results demonstrate that motions at the domain interface dynamically impact the conformation of the RNA-binding surface and may provide an adaptive separation distance that is necessary to allow interactions with a variety of different pri-miRNAs with heterogeneous structures. These results thus provide an entry point for further in vitro studies of the potentially unique RNA-binding mode of DGCR8.
在过去的十年中，研究表明 microRNAs（miRNAs）通过与信使 RNA 碱基配对来影响基因调控，其失调与癌症直接相关。DGCR8 是一种含有两个串联 dsRNA 结合域（dsRBD）的蛋白质，对于与 RNase III 酶 Drosha 相关的初级 miRNA（pri-miRNA）的核成熟至关重要。DGCR8 Core（493-720）的晶体结构显示了两个 dsRBD 之间连接区的独特、有序结构，与抗病毒反应蛋白 PKR 中连接两个 dsRBD 的柔性连接不同。为了更好地理解两个 dsRBD 之间的界面相互作用，我们对分离的 dsRBD（505-583 和 614-691）和 Core 进行了广泛的 MD 模拟。模拟结果表明，两个结构域之间存在相对的相关性重新定向，有序的连接区和 C 末端充当枢轴。结果表明，结构域界面的运动动态地影响 RNA 结合表面的构象，并可能提供必要的自适应分离距离，以允许与具有不同结构的各种不同 pri-miRNA 相互作用。因此，这些结果为进一步研究 DGCR8 潜在独特的 RNA 结合模式提供了一个切入点。
