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7ssw

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Late translocation intermediate with EF-G dissociated (Structure VI)

Structural highlights

7ssw is a 10 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 3.8Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

RL14_ECOLI This protein binds directly to 23S ribosomal RNA. In the E.coli 70S ribosome (PubMed:12809609) it has been modeled to make two contacts with the 16S rRNA of the 30S subunit, forming part of bridges B5 and B8, connecting the 2 subunits. Although the protein undergoes significant rotation during the transition from an initiation to and EF-G bound state, the bridges remain stable. In the 3.5 A resolved structures (PubMed:16272117) L14 and L19 interact and together make contact with the 16S rRNA in bridges B5 and B8.^[1] Can also interact with RsfA, in this case bridge B8 probably cannot form, and the 30S and 50S ribosomal subunits do not associate, which represses translation.^[2]

Publication Abstract from PubMed

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 ~20 A. An additional 4-A 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.

Time-resolved cryo-EM visualizes ribosomal translocation with EF-G and GTP.,Carbone CE, Loveland AB, Gamper HB Jr, Hou YM, Demo G, Korostelev AA Nat Commun. 2021 Dec 13;12(1):7236. doi: 10.1038/s41467-021-27415-0. PMID:34903725^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Hauser R, Pech M, Kijek J, Yamamoto H, Titz B, Naeve F, Tovchigrechko A, Yamamoto K, Szaflarski W, Takeuchi N, Stellberger T, Diefenbacher ME, Nierhaus KH, Uetz P. RsfA (YbeB) proteins are conserved ribosomal silencing factors. PLoS Genet. 2012;8(7):e1002815. doi: 10.1371/journal.pgen.1002815. Epub 2012 Jul , 19. PMID:22829778 doi:10.1371/journal.pgen.1002815
↑ Hauser R, Pech M, Kijek J, Yamamoto H, Titz B, Naeve F, Tovchigrechko A, Yamamoto K, Szaflarski W, Takeuchi N, Stellberger T, Diefenbacher ME, Nierhaus KH, Uetz P. RsfA (YbeB) proteins are conserved ribosomal silencing factors. PLoS Genet. 2012;8(7):e1002815. doi: 10.1371/journal.pgen.1002815. Epub 2012 Jul , 19. PMID:22829778 doi:10.1371/journal.pgen.1002815
↑ Carbone CE, Loveland AB, Gamper HB Jr, Hou YM, Demo G, Korostelev AA. Time-resolved cryo-EM visualizes ribosomal translocation with EF-G and GTP. Nat Commun. 2021 Dec 13;12(1):7236. PMID:34903725 doi:10.1038/s41467-021-27415-0