Cell, Molecular and Developmental Biology and Biophysics Program, Johns Hopkins University, Baltimore, MD 21218.
Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218.
Proc Natl Acad Sci U S A. 2019 May 28;116(22):10978-10987. doi: 10.1073/pnas.1814428116. Epub 2019 May 10.
We have solved the X-ray crystal structure of the RNA chaperone protein Hfq from the alpha-proteobacterium to 2.15-Å resolution, resolving the conserved core of the protein and the entire C-terminal domain (CTD). The structure reveals that the CTD of neighboring hexamers pack in crystal contacts, and that the acidic residues at the C-terminal tip of the protein interact with positive residues on the rim of Hfq, as has been recently proposed for a mechanism of modulating RNA binding. De novo computational models predict a similar docking of the acidic tip residues against the core of Hfq. We also show that Hfq has sRNA binding and RNA annealing activities and is capable of facilitating the annealing of certain sRNA:mRNA pairs in vivo. Finally, we describe how the Hfq CTD and its acidic tip residues provide a mechanism to modulate annealing activity and substrate specificity in various bacteria.
我们解析了α-变形菌的 RNA 伴侣蛋白 Hfq 的 X 射线晶体结构，分辨率达到 2.15Å，解析了该蛋白的保守核心和整个 C 端结构域（CTD）。结构显示，相邻六聚体的 CTD 在晶体接触中组装，并且蛋白质 C 端末端的酸性残基与 Hfq 边缘的阳性残基相互作用，最近提出了一种调节 RNA 结合的机制。从头计算模型预测了酸性末端残基与 Hfq 核心的类似对接。我们还表明，Hfq 具有 sRNA 结合和 RNA 退火活性，并能够促进某些 sRNA:mRNA 对在体内的退火。最后，我们描述了 Hfq CTD 及其酸性末端残基如何为各种细菌中调节退火活性和底物特异性提供机制。
