scholarly journals Active role of elongation factor G in maintaining the mRNA reading frame during translation

2019 ◽  
Vol 5 (12) ◽  
pp. eaax8030 ◽  
Author(s):  
Bee-Zen Peng ◽  
Lars V. Bock ◽  
Riccardo Belardinelli ◽  
Frank Peske ◽  
Helmut Grubmüller ◽  
...  
Keyword(s):  
Elongation Factor ◽  
Active Role ◽  
Transfer Rna ◽  
Specific Interactions ◽  
Elongation Factor G ◽  
Reading Frame ◽  
A Site ◽  
Factor G ◽  
Domain 4

During translation, the ribosome moves along the mRNA one codon at a time with the help of elongation factor G (EF-G). Spontaneous changes in the translational reading frame are extremely rare, yet how the precise triplet-wise step is maintained is not clear. Here, we show that the ribosome is prone to spontaneous frameshifting on mRNA slippery sequences, whereas EF-G restricts frameshifting. EF-G helps to maintain the mRNA reading frame by guiding the A-site transfer RNA during translocation due to specific interactions with the tip of EF-G domain 4. Furthermore, EF-G accelerates ribosome rearrangements that restore the ribosome’s control over the codon-anticodon interaction at the end of the movement. Our data explain how the mRNA reading frame is maintained during translation.

Converting GTP hydrolysis into motion: versatile translational elongation factor G

2019 ◽  
Vol 401 (1) ◽  
pp. 131-142 ◽  
Author(s):  
Marina V. Rodnina ◽  
Frank Peske ◽  
Bee-Zen Peng ◽  
Riccardo Belardinelli ◽  
Wolfgang Wintermeyer
Keyword(s):  
Elongation Factor ◽  
Ribosome Recycling Factor ◽  
Canonical Function ◽  
Elongation Factor G ◽  
Translation Elongation ◽  
Gtp Hydrolysis ◽  
Reading Frame ◽  
Gtpase Cycle ◽  
A Site ◽  
Factor G

Abstract Elongation factor G (EF-G) is a translational GTPase that acts at several stages of protein synthesis. Its canonical function is to catalyze tRNA movement during translation elongation, but it also acts at the last step of translation to promote ribosome recycling. Moreover, EF-G has additional functions, such as helping the ribosome to maintain the mRNA reading frame or to slide over non-coding stretches of the mRNA. EF-G has an unconventional GTPase cycle that couples the energy of GTP hydrolysis to movement. EF-G facilitates movement in the GDP-Pi form. To convert the energy of hydrolysis to movement, it requires various ligands in the A site, such as a tRNA in translocation, an mRNA secondary structure element in ribosome sliding, or ribosome recycling factor in post-termination complex disassembly. The ligand defines the direction and timing of EF-G-facilitated motion. In this review, we summarize recent advances in understanding the mechanism of EF-G action as a remarkable force-generating GTPase.

scholarly journals Spontaneous ribosomal translocation of mRNA and tRNAs into a chimeric hybrid state

2019 ◽  
Vol 116 (16) ◽  
pp. 7813-7818 ◽  
Author(s):  
Jie Zhou ◽  
Laura Lancaster ◽  
John Paul Donohue ◽  
Harry F. Noller
Keyword(s):  
Crystal Structure ◽  
Elongation Factor ◽  
Intermediate Complex ◽  
Reading Frame ◽  
Hybrid State ◽  
Head Domain ◽  
30S Subunit ◽  
A Site ◽  
Insight Into ◽  
Factor G

The elongation factor G (EF-G)–catalyzed translocation of mRNA and tRNA through the ribosome is essential for vacating the ribosomal A site for the next incoming aminoacyl-tRNA, while precisely maintaining the translational reading frame. Here, the 3.2-Å crystal structure of a ribosome translocation intermediate complex containing mRNA and two tRNAs, formed in the absence of EF-G or GTP, provides insight into the respective roles of EF-G and the ribosome in translocation. Unexpectedly, the head domain of the 30S subunit is rotated by 21°, creating a ribosomal conformation closely resembling the two-tRNA chimeric hybrid state that was previously observed only in the presence of bound EF-G. The two tRNAs have moved spontaneously from their A/A and P/P binding states into ap/P and pe/E states, in which their anticodon loops are bound between the 30S body domain and its rotated head domain, while their acceptor ends have moved fully into the 50S P and E sites, respectively. Remarkably, the A-site tRNA translocates fully into the classical P-site position. Although the mRNA also undergoes movement, codon–anticodon interaction is disrupted in the absence of EF-G, resulting in slippage of the translational reading frame. We conclude that, although movement of both tRNAs and mRNA (along with rotation of the 30S head domain) can occur in the absence of EF-G and GTP, EF-G is essential for enforcing coupled movement of the tRNAs and their mRNA codons to maintain the reading frame.

scholarly journals EF-G–induced ribosome sliding along the noncoding mRNA

2019 ◽  
Vol 5 (6) ◽  
pp. eaaw9049 ◽  
Author(s):  
M. Klimova ◽  
T. Senyushkina ◽  
E. Samatova ◽  
B. Z. Peng ◽  
M. Pearson ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Elongation Factor ◽  
Transfer Rna ◽  
Noncoding Region ◽  
Forward Movement ◽  
Stem Loop ◽  
A Site ◽  
Hydrolysis Of ◽  
Reading Frames ◽  
Factor G

Translational bypassing is a recoding event during which ribosomes slide over a noncoding region of the messenger RNA (mRNA) to synthesize one protein from two discontinuous reading frames. Structures in the mRNA orchestrate forward movement of the ribosome, but what causes ribosomes to start sliding remains unclear. Here, we show that elongation factor G (EF-G) triggers ribosome take-off by a pseudotranslocation event using a small mRNA stem-loop as an A-site transfer RNA mimic and requires hydrolysis of about two molecules of guanosine 5′-triphosphate per nucleotide of the noncoding gap. Bypassing ribosomes adopt a hyper-rotated conformation, also observed with ribosomes stalled by the SecM sequence, suggesting common ribosome dynamics during translation stalling. Our results demonstrate a new function of EF-G in promoting ribosome sliding along the mRNA, in contrast to codon-wise ribosome movement during canonical translation, and suggest a mechanism by which ribosomes could traverse untranslated parts of mRNAs.

scholarly journals Activation of GTP hydrolysis in mRNA-tRNA translocation by elongation factor G

2015 ◽  
Vol 1 (4) ◽  
pp. e1500169 ◽  
Author(s):  
Wen Li ◽  
Zheng Liu ◽  
Ravi Kiran Koripella ◽  
Robert Langlois ◽  
Suparna Sanyal ◽  
...  
Keyword(s):  
Elongation Factor ◽  
Elongation Factor G ◽  
Direct Role ◽  
Gtp Hydrolysis ◽  
Ribosomal Subunits ◽  
Trna Translocation ◽  
Gtpase Activation ◽  
Guanosine Triphosphatase ◽  
Factor G

During protein synthesis, elongation of the polypeptide chain by each amino acid is followed by a translocation step in which mRNA and transfer RNA (tRNA) are advanced by one codon. This crucial step is catalyzed by elongation factor G (EF-G), a guanosine triphosphatase (GTPase), and accompanied by a rotation between the two ribosomal subunits. A mutant of EF-G, H91A, renders the factor impaired in guanosine triphosphate (GTP) hydrolysis and thereby stabilizes it on the ribosome. We use cryogenic electron microscopy (cryo-EM) at near-atomic resolution to investigate two complexes formed by EF-G H91A in its GTP state with the ribosome, distinguished by the presence or absence of the intersubunit rotation. Comparison of these two structures argues in favor of a direct role of the conserved histidine in the switch II loop of EF-G in GTPase activation, and explains why GTP hydrolysis cannot proceed with EF-G bound to the unrotated form of the ribosome.

scholarly journals The Role of Guanosine Triphosphate in Translocation Reaction Catalyzed by Elongation Factor G

1974 ◽  
Vol 249 (13) ◽  
pp. 4321-4323
Author(s):  
Noriko Inoue-Yokosawa ◽  
Chikako Ishikawa ◽  
Yoshito Kaziro
Keyword(s):  
Elongation Factor ◽  
Guanosine Triphosphate ◽  
Elongation Factor G ◽  
Factor G

scholarly journals Structural basis for +1 ribosomal frameshifting during EF-G-catalyzed translocation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gabriel Demo ◽  
Howard B. Gamper ◽  
Anna B. Loveland ◽  
Isao Masuda ◽  
Christine E. Carbone ◽  
...  
Keyword(s):  
16S Rrna ◽  
Elongation Factor ◽  
Structural Basis ◽  
Elongation Factor G ◽  
Ribosomal Frameshifting ◽  
Elongation Cycle ◽  
70S Ribosome ◽  
Complex Features ◽  
A Site ◽  
Factor G

AbstractFrameshifting of mRNA during translation provides a strategy to expand the coding repertoire of cells and viruses. How and where in the elongation cycle +1-frameshifting occurs remains poorly understood. We describe seven ~3.5-Å-resolution cryo-EM structures of 70S ribosome complexes, allowing visualization of elongation and translocation by the GTPase elongation factor G (EF-G). Four structures with a + 1-frameshifting-prone mRNA reveal that frameshifting takes place during translocation of tRNA and mRNA. Prior to EF-G binding, the pre-translocation complex features an in-frame tRNA-mRNA pairing in the A site. In the partially translocated structure with EF-G•GDPCP, the tRNA shifts to the +1-frame near the P site, rendering the freed mRNA base to bulge between the P and E sites and to stack on the 16S rRNA nucleotide G926. The ribosome remains frameshifted in the nearly post-translocation state. Our findings demonstrate that the ribosome and EF-G cooperate to induce +1 frameshifting during tRNA-mRNA translocation.

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