期刊
NATURE COMMUNICATIONS
卷 12, 期 1, 页码 -出版社
NATURE PORTFOLIO
DOI: 10.1038/s41467-021-27415-0
关键词
-
资金
- MEYS CR as part of the ERC CZ program [LL2008]
- Czech Science Foundation [GJ20-16013Y]
- NIH
- [F31 HL152650]
- [R35 GM134931]
- [R35 GM127094]
This study visualized the structures of ribosome-EF-G intermediates at near-atomic resolution using time-resolved cryo-EM, revealing how EF-G rectifies ribosomal dynamics into tRNA-mRNA translocation. The mechanism of EF-G in translocating tRNA and mRNA through the ribosome involves a combination of motor- and pawl-like mechanisms, with GTP hydrolysis and Pi release driving EF-G dissociation.
During translation, a conserved GTPase elongation factor-EF-G in bacteria or eEF2 in eukaryotes-translocates tRNA and mRNA through the ribosome. EF-G has been proposed to act as a flexible motor that propels tRNA and mRNA movement, as a rigid pawl that biases unidirectional translocation resulting from ribosome rearrangements, or by various combinations of motor- and pawl-like mechanisms. Using time-resolved cryo-EM, we visualized GTP-catalyzed translocation without inhibitors, capturing elusive structures of ribosome.EF-G intermediates at near-atomic resolution. Prior to translocation, EF-G binds near peptidyl-tRNA, while the rotated 30S subunit stabilizes the EF-G GTPase center. Reverse 30S rotation releases Pi and translocates peptidyl-tRNA and EF-G by similar to 20 angstrom. An additional 4-angstrom translocation initiates EF-G dissociation from a transient ribosome state with highly swiveled 30S head. The structures visualize how nearly rigid EF-G rectifies inherent and spontaneous ribosomal dynamics into tRNA-mRNA translocation, whereas GTP hydrolysis and Pi release drive EF-G dissociation.
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