Khusainov Iskander, Vicens Quentin, Ayupov Rustam, Usachev Konstantin, Myasnikov Alexander, Simonetti Angelita, Validov Shamil, Kieffer Bruno, Yusupova Gulnara, Yusupov Marat, Hashem Yaser
Département de Biologie et de Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR7104, INSERM U964, Université de Strasbourg, Illkirch, France.
Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia.
EMBO J. 2017 Jul 14;36(14):2073-2087. doi: 10.15252/embj.201696105. Epub 2017 Jun 23.
In bacteria, ribosomal hibernation shuts down translation as a response to stress, through reversible binding of stress-induced proteins to ribosomes. This process typically involves the formation of 100S ribosome dimers. Here, we present the structures of hibernating ribosomes from human pathogen containing a long variant of the hibernation-promoting factor (SaHPF) that we solved using cryo-electron microscopy. Our reconstructions reveal that the N-terminal domain (NTD) of SaHPF binds to the 30S subunit as observed for shorter variants of HPF in other species. The C-terminal domain (CTD) of SaHPF protrudes out of each ribosome in order to mediate dimerization. Using NMR, we characterized the interactions at the CTD-dimer interface. Secondary interactions are provided by helix 26 of the 16S ribosomal RNA We also show that ribosomes in the 100S particle adopt both rotated and unrotated conformations. Overall, our work illustrates a specific mode of ribosome dimerization by long HPF, a finding that may help improve the selectivity of antimicrobials.
在细菌中，核糖体休眠通过应激诱导蛋白与核糖体的可逆结合来关闭翻译过程，作为对压力的一种反应。这个过程通常涉及100S核糖体二聚体的形成。在这里，我们展示了来自人类病原体的休眠核糖体的结构，其中含有一种促进休眠因子（SaHPF）的长变体，我们使用冷冻电子显微镜解析了其结构。我们的重建结果显示，正如在其他物种中观察到的较短HPF变体一样，SaHPF的N端结构域（NTD）与30S亚基结合。SaHPF的C端结构域（CTD）从每个核糖体中伸出，以介导二聚化。我们使用核磁共振（NMR）对CTD-二聚体界面处的相互作用进行了表征。16S核糖体RNA的螺旋26提供了二级相互作用。我们还表明，100S颗粒中的核糖体采用旋转和未旋转两种构象。总体而言，我们的工作阐明了长HPF介导核糖体二聚化的一种特定模式，这一发现可能有助于提高抗菌药物的选择性。
