Bertrand Beckert / Martin Turk / Andreas Czech / Otto Berninghausen / Roland Beckmann / Zoya Ignatova / Jürgen M Plitzko / Daniel N Wilson /
PubMed 要旨
To survive under conditions of stress, such as nutrient deprivation, bacterial 70S ribosomes dimerize to form hibernating 100S particles. In γ-proteobacteria, such as Escherichia coli, 100S ...To survive under conditions of stress, such as nutrient deprivation, bacterial 70S ribosomes dimerize to form hibernating 100S particles. In γ-proteobacteria, such as Escherichia coli, 100S formation requires the ribosome modulation factor (RMF) and the hibernation promoting factor (HPF). Here we present single-particle cryo-electron microscopy structures of hibernating 70S and 100S particles isolated from stationary-phase E. coli cells at 3.0 Å and 7.9 Å resolution, respectively. The structures reveal the binding sites for HPF and RMF as well as the unexpected presence of deacylated E-site transfer RNA and ribosomal protein bS1. HPF interacts with the anticodon-stem-loop of the E-tRNA and occludes the binding site for the messenger RNA as well as A- and P-site tRNAs. RMF facilitates stabilization of a compact conformation of bS1, which together sequester the anti-Shine-Dalgarno sequence of the 16S ribosomal RNA (rRNA), thereby inhibiting translation initiation. At the dimerization interface, the C-terminus of uS2 probes the mRNA entrance channel of the symmetry-related particle, thus suggesting that dimerization inactivates ribosomes by blocking the binding of mRNA within the channel. The back-to-back E. coli 100S arrangement is distinct from 100S particles observed previously in Gram-positive bacteria, and reveals a unique role for bS1 in translation regulation.
EMDB-0137, PDB-6h4n: Structure of a hibernating 100S ribosome reveals an inactive conformation of the ribosomal protein S1 - 70S Hibernating E. coli Ribosome 手法: EM (単粒子) / 解像度: 3.0 Å
EMDB-0139, PDB-6h58: Structure of a hibernating 100S ribosome reveals an inactive conformation of the ribosomal protein S1 - Full 100S Hibernating E. coli Ribosome 手法: EM (単粒子) / 解像度: 7.9 Å