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

Frameshifting of mRNA during translation provides a strategy to expand the coding repertoire of cells and viruses. Where and how in the elongation cycle +1-frameshifting occurs remains poorly understood. We captured six ~3.5-Å-resolution cryo-EM structures of ribosomal elongation complexes formed with the GTPase elongation factor G (EF-G). Three 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, the tRNA shifts to the +1-frame codon near the P site, whereas the freed mRNA base bulges between the P and E sites and stacks 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 mRNA translocation.

Download Full-text

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

Nature Communications ◽

10.1038/s41467-021-24911-1 ◽

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.

Download Full-text

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

Science Advances ◽

10.1126/sciadv.aax8030 ◽

2019 ◽

Vol 5 (12) ◽

pp. eaax8030 ◽

Cited By ~ 6

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.

Download Full-text

Converting GTP hydrolysis into motion: versatile translational elongation factor G

Biological Chemistry ◽

10.1515/hsz-2019-0313 ◽

2019 ◽

Vol 401 (1) ◽

pp. 131-142 ◽

Cited By ~ 2

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.

Download Full-text