Ratchet-like Movements between the Two Ribosomal Subunits: Their Implications in Elongation Factor Recognition and tRNA Translocation

2001 ◽  
Vol 66 (0) ◽  
pp. 67-76 ◽  
Author(s):  
J. FRANK ◽  
R.K. AGRAWAL
Keyword(s):  
Elongation Factor ◽  
Ribosomal Subunits ◽  
Trna Translocation

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 Yeast translation elongation factor eEF3 promotes late stages of tRNA translocation

2021 ◽  
Author(s):  
Namit Ranjan ◽  
Agnieszka A Pochopien ◽  
Colin Chih‐Chien Wu ◽  
Bertrand Beckert ◽  
Sandra Blanchet ◽  
...  
Keyword(s):  
Elongation Factor ◽  
Translation Elongation Factor ◽  
Translation Elongation ◽  
Trna Translocation ◽  
Late Stages

scholarly journals Decreased activity of peptide-elongation factors after treatment with cholesterol esterase

1978 ◽  
Vol 172 (1) ◽  
pp. 9-13 ◽  
Author(s):  
J Hradec ◽  
Z Tuháčková ◽  
Z Dušek
Keyword(s):  
Phospholipase A2 ◽  
Elongation Factor ◽  
Normal Activity ◽  
Normal Function ◽  
Cholesterol Esterase ◽  
Elongation Factors ◽  
Ribosomal Subunits ◽  
Binding Factor ◽  
Peptide Elongation ◽  
Sepharose 4B

1. Peptide-elongation factors were purified from rat liver and treated with cholesterol esterase and phospholipase A2 immobilized on Sepharose 4B. 2. Binding of L-[3H]-phenylalanyl-tRNA to 40S ribosomal subunits was decreased by approx. 70% and to polyribosomes by 30% in the presence of the binding factor incubated with cholesterol esterase. Treatment of this factor with immobilized phospholipase A2 decreased the binding to smaller ribosomal subunits by only about 15%. 3. Poly(U)-dependent phenylalanine polymerization by ribosomal subunits was decreased to approx. 30% of its original value by treatment of both elongation factors with cholesterol esterase. 4. The normal activity of esterase-treated elongation factor in both the binding reaction and peptide-elongation assay was fully recovered by the addition of cholesteryl 14-methyl-hexadecanoate. 5. Different classes of lipids present in peptide-elongation factor 1 have apparently different functions. Whereas phospholipids are required to maintain the strcture of heavy aggregates of this factor, the presence of cholesteryl 14-methylhexadecanoate is obviously necessary for the normal function of peptide-elongation factors.

scholarly journals eEF3 promotes late stages of tRNA translocation on the ribosome

2020 ◽  
Author(s):  
Namit Ranjan ◽  
Agnieszka A. Pochopien ◽  
Colin Chih-Chien Wu ◽  
Bertrand Beckert ◽  
Sandra Blanchet ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Elongation Factor ◽  
Translation Elongation ◽  
Elongation Cycle ◽  
Trna Translocation ◽  
A Site ◽  
Late Stages ◽  
Structural Insights ◽  
Trna Binding

SummaryIn addition to the conserved translation elongation factors eEF1A and eEF2, fungi require a third essential elongation factor, eEF3. While eEF3 has been implicated in tRNA binding and release at the A and E sites, its exact mechanism of action is unclear. Here we show that eEF3 acts at the mRNA–tRNA translocation step by promoting the dissociation of the tRNA from the E site, but independent of aminoacyl-tRNA recruitment to the A site. Depletion of eEF3 in vivo leads to a general slow-down in translation elongation due to accumulation of ribosomes with an occupied A site. Cryo-EM analysis of ex vivo eEF3-ribosome complexes shows that eEF3 facilitates late steps of translocation by favoring non-rotated ribosomal states as well as by opening the L1 stalk to release the E-site tRNA. Additionally, our analysis provides structural insights into novel translation elongation states, enabling presentation of a revised yeast translation elongation cycle.

scholarly journals Crystal Structure of Mycobacterium tuberculosis Elongation Factor G1

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiaopan Gao ◽  
Xia Yu ◽  
Kaixiang Zhu ◽  
Bo Qin ◽  
Wei Wang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mycobacterium Tuberculosis ◽  
Drug Target ◽  
Drug Targets ◽  
Elongation Factor ◽  
Protein Translation ◽  
Crystal Form ◽  
Multidrug Resistant ◽  
Major Focus ◽  
Trna Translocation

Mycobacterium tuberculosis (Mtb) caused an estimated 10 million cases of tuberculosis and 1.2 million deaths in 2019 globally. The increasing emergence of multidrug-resistant and extensively drug-resistant Mtb is becoming a public health threat worldwide and makes the identification of anti-Mtb drug targets urgent. Elongation factor G (EF-G) is involved in tRNA translocation on ribosomes during protein translation. Therefore, EF-G is a major focus of structural analysis and a valuable drug target of antibiotics. However, the crystal structure of Mtb EF-G1 is not yet available, and this has limited the design of inhibitors. Here, we report the crystal structure of Mtb EF-G1 in complex with GDP. The unique crystal form of the Mtb EF-G1-GDP complex provides an excellent platform for fragment-based screening using a crystallographic approach. Our findings provide a structure-based explanation for GDP recognition, and facilitate the identification of EF-G1 inhibitors with potential interest in the context of drug discovery.

scholarly journals Allosteric collaboration between elongation factor G and the ribosomal L1 stalk directs tRNA movements during translation

2009 ◽  
Vol 106 (37) ◽  
pp. 15702-15707 ◽  
Author(s):  
Jingyi Fei ◽  
Jonathan E. Bronson ◽  
Jake M. Hofman ◽  
Rathi L. Srinivas ◽  
Chris H. Wiggins ◽  
...  
Keyword(s):  
Dynamic Equilibrium ◽  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Large Ribosomal Subunit ◽  
Elongation Factor G ◽  
Structural Element ◽  
Time Dynamics ◽  
Kinetic Mechanisms ◽  
Trna Translocation ◽  
Factor G

Determining the mechanism by which tRNAs rapidly and precisely transit through the ribosomal A, P, and E sites during translation remains a major goal in the study of protein synthesis. Here, we report the real-time dynamics of the L1 stalk, a structural element of the large ribosomal subunit that is implicated in directing tRNA movements during translation. Within pretranslocation ribosomal complexes, the L1 stalk exists in a dynamic equilibrium between open and closed conformations. Binding of elongation factor G (EF-G) shifts this equilibrium toward the closed conformation through one of at least two distinct kinetic mechanisms, where the identity of the P-site tRNA dictates the kinetic route that is taken. Within posttranslocation complexes, L1 stalk dynamics are dependent on the presence and identity of the E-site tRNA. Collectively, our data demonstrate that EF-G and the L1 stalk allosterically collaborate to direct tRNA translocation from the P to the E sites, and suggest a model for the release of E-site tRNA.

scholarly journals Low Energy Barriers and a Dynamic Contact Network between Ribosomal Subunits Enable Rapid tRNA Translocation

2016 ◽  
Vol 110 (3) ◽  
pp. 3a
Author(s):  
Lars V. Bock ◽  
Christian Blau ◽  
Andrea C. Vaiana ◽  
Helmut Grubmuller
Keyword(s):  
Dynamic Contact ◽  
Low Energy ◽  
Contact Network ◽  
Energy Barriers ◽  
Ribosomal Subunits ◽  
Trna Translocation

scholarly journals Molecular Functions of Conserved Developmentally-Regulated GTP-Binding Protein Drg1 in Translation

2020 ◽  
Author(s):  
Fuxing Zeng ◽  
Melissa Pires-Alves ◽  
Christopher W. Hawk ◽  
Xin Chen ◽  
Hong Jin
Keyword(s):  
Elongation Factor ◽  
Peptide Bond ◽  
Peptide Bond Formation ◽  
Developmentally Regulated ◽  
Single Particle Reconstruction ◽  
Peptidyl Transfer ◽  
Gtp Binding ◽  
Processing Pathways ◽  
Trna Translocation ◽  
Ribosome Pausing

SUMMARYDevelopmentally-regulated GTP-binding (Drg) proteins are important for embryonic development, cell growth, proliferation, and differentiation. Despite their highly conserved nature, the functions of Drg proteins in translation are unknown. Here, we demonstrate the yeast Drg ortholog, Rbg1, alleviates ribosome pausing at Arginine/Lysine-rich regions in mRNAs, and mainly targets genes related to ribonucleoprotein complex biogenesis and non-coding RNA processing pathways. Furthermore, we reveal the global architecture of the ribosome and the molecular interactions involved when Rbg1 and its binding partner, Tma46, associate with the ribosome using biochemistry and single particle reconstruction using cryoEM. Our data show that Rbg1/Tma46 associate with the larger subunit of ribosome via the N-terminal zinc finger domain in Tma46, and that the protein complex helps to enrich translating ribosomes in the post-peptidyl transfer state, after peptide-bond formation, but before elongation factor binding and tRNA translocation. Based on our results and the conserved nature of Drg proteins, broader functions of the Drg proteins in the protein synthesis and quality control pathways of eukaryotic cells are proposed.

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