scholarly journals pH-sensitivity of the ribosomal peptidyl transfer reaction dependent on the identity of the A-site aminoacyl-tRNA

2010 ◽  
Vol 108 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Magnus Johansson ◽  
Ka-Weng Ieong ◽  
Stefan Trobro ◽  
Peter Strazewski ◽  
Johan Åqvist ◽  
...  
Keyword(s):  
Ph Value ◽  
Ph Dependence ◽  
Peptide Bond ◽  
Bulk Solution ◽  
Peptide Bond Formation ◽  
Transfer Rates ◽  
Peptidyl Transfer ◽  
A Site ◽  
Rate Limiting ◽  
Site Binding

We studied the pH-dependence of ribosome catalyzed peptidyl transfer from fMet-tRNAfMet to the aa-tRNAs Phe-tRNAPhe, Ala-tRNAAla, Gly-tRNAGly, Pro-tRNAPro, Asn-tRNAAsn, and Ile-tRNAIle, selected to cover a large range of intrinsic pKa-values for the α-amino group of their amino acids. The peptidyl transfer rates were different at pH 7.5 and displayed different pH-dependence, quantified as the pH-value, , at which the rate was half maximal. The -values were downshifted relative to the intrinsic pKa-value of aa-tRNAs in bulk solution. Gly-tRNAGly had the smallest downshift, while Ile-tRNAIle and Ala-tRNAAla had the largest downshifts. These downshifts correlate strongly with molecular dynamics (MD) estimates of the downshifts in pKa-values of these aa-tRNAs upon A-site binding. Our data show the chemistry of peptide bond formation to be rate limiting for peptidyl transfer at pH 7.5 in the Gly and Pro cases and indicate rate limiting chemistry for all six aa-tRNAs.

scholarly journals Multifaceted Mechanism of Amicoumacin A Inhibition of Bacterial Translation

2021 ◽  
Vol 12 ◽  
Author(s):  
Elena M. Maksimova ◽  
Daria S. Vinogradova ◽  
Ilya A. Osterman ◽  
Pavel S. Kasatsky ◽  
Oleg S. Nikonov ◽  
...  
Keyword(s):  
Peptide Bond ◽  
Inhibitory Mechanism ◽  
Peptide Bond Formation ◽  
Thermodynamic Investigation ◽  
Translation Inhibition ◽  
Complete Restoration ◽  
Polypeptide Synthesis ◽  
Activity Loss ◽  
A Site ◽  
Site Binding

Amicoumacin A (Ami) halts bacterial growth by inhibiting the ribosome during translation. The Ami binding site locates in the vicinity of the E-site codon of mRNA. However, Ami does not clash with mRNA, rather stabilizes it, which is relatively unusual and implies a unique way of translation inhibition. In this work, we performed a kinetic and thermodynamic investigation of Ami influence on the main steps of polypeptide synthesis. We show that Ami reduces the rate of the functional canonical 70S initiation complex (IC) formation by 30-fold. Additionally, our results indicate that Ami promotes the formation of erroneous 30S ICs; however, IF3 prevents them from progressing towards translation initiation. During early elongation steps, Ami does not compromise EF-Tu-dependent A-site binding or peptide bond formation. On the other hand, Ami reduces the rate of peptidyl-tRNA movement from the A to the P site and significantly decreases the amount of the ribosomes capable of polypeptide synthesis. Our data indicate that Ami progressively decreases the activity of translating ribosomes that may appear to be the main inhibitory mechanism of Ami. Indeed, the use of EF-G mutants that confer resistance to Ami (G542V, G581A, or ins544V) leads to a complete restoration of the ribosome functionality. It is possible that the changes in translocation induced by EF-G mutants compensate for the activity loss caused by Ami.

scholarly journals Essential Mechanisms in the Catalysis of Peptide Bond Formation on the Ribosome

2005 ◽  
Vol 280 (43) ◽  
pp. 36065-36072 ◽  
Author(s):  
Malte Beringer ◽  
Christian Bruell ◽  
Liqun Xiong ◽  
Peter Pfister ◽  
Peter Bieling ◽  
...  
Keyword(s):  
Ph Dependence ◽  
Bond Formation ◽  
Peptide Bond ◽  
Activation Entropy ◽  
Peptide Bond Formation ◽  
Peptidyl Transferase ◽  
Peptidyl Transferase Center ◽  
Chemical Catalysis ◽  
Catalytic Function ◽  
Peptidyl Transfer

Peptide bond formation is the main catalytic function of the ribo-some. The mechanism of catalysis is presumed to be highly conserved in all organisms. We tested the conservation by comparing mechanistic features of the peptidyl transfer reaction on ribosomes from Escherichia coli and the Gram-positive bacterium Mycobacterium smegmatis. In both cases, the major contribution to catalysis was the lowering of the activation entropy. The rate of peptide bond formation was pH independent with the natural substrate, amino-acyl-tRNA, but was slowed down 200-fold with decreasing pH when puromycin was used as a substrate analog. Mutation of the conserved base A2451 of 23 S rRNA to U did not abolish the pH dependence of the reaction with puromycin in M. smegmatis, suggesting that A2451 did not confer the pH dependence. However, the A2451U mutation alters the structure of the peptidyl transferase center and changes the pattern of pH-dependent rearrangements, as probed by chemical modification of 23 S rRNA. A2451 seems to function as a pivot point in ordering the structure of the peptidyl transferase center rather than taking part in chemical catalysis.

scholarly journals Disome-seq reveals widespread ribosome collisions that promote cotranslational protein folding

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Taolan Zhao ◽  
Yan-Ming Chen ◽  
Yu Li ◽  
Jia Wang ◽  
Siyu Chen ◽  
...  
Keyword(s):  
Protein Quality ◽  
Peptide Bond ◽  
Peptide Bond Formation ◽  
Translation Elongation ◽  
Cryo Electron Microscopy ◽  
Cotranslational Folding ◽  
A Cell ◽  
Exit Tunnel ◽  
Hidden Layer ◽  
A Site

Abstract Background The folding of proteins is challenging in the highly crowded and sticky environment of a cell. Regulation of translation elongation may play a crucial role in ensuring the correct folding of proteins. Much of our knowledge regarding translation elongation comes from the sequencing of mRNA fragments protected by single ribosomes by ribo-seq. However, larger protected mRNA fragments have been observed, suggesting the existence of an alternative and previously hidden layer of regulation. Results In this study, we performed disome-seq to sequence mRNA fragments protected by two stacked ribosomes, a product of translational pauses during which the 5′-elongating ribosome collides with the 3′-paused one. We detected widespread ribosome collisions that are related to slow ribosome release when stop codons are at the A-site, slow peptide bond formation from proline, glycine, asparagine, and cysteine when they are at the P-site, and slow leaving of polylysine from the exit tunnel of ribosomes. The structure of disomes obtained by cryo-electron microscopy suggests a different conformation from the substrate of the ribosome-associated protein quality control pathway. Collisions occurred more frequently in the gap regions between α-helices, where a translational pause can prevent the folding interference from the downstream peptides. Paused or collided ribosomes are associated with specific chaperones, which can aid in the cotranslational folding of the nascent peptides. Conclusions Therefore, cells use regulated ribosome collisions to ensure protein homeostasis.

scholarly journals EF-P Is Essential for Rapid Synthesis of Proteins Containing Consecutive Proline Residues

Science ◽  
2012 ◽  
Vol 339 (6115) ◽  
pp. 85-88 ◽  
Author(s):  
Lili K. Doerfel ◽  
Ingo Wohlgemuth ◽  
Christina Kothe ◽  
Frank Peske ◽  
Henning Urlaub ◽  
...  
Keyword(s):  
Unknown Function ◽  
Bond Formation ◽  
Elongation Factor ◽  
Peptide Bond ◽  
Transfer Rna ◽  
Peptide Bond Formation ◽  
Rapid Synthesis ◽  
Catalytic Center ◽  
Cellular Processes ◽  
Peptidyl Transfer

Elongation factor P (EF-P) is a translation factor of unknown function that has been implicated in a great variety of cellular processes. Here, we show that EF-P prevents ribosome from stalling during synthesis of proteins containing consecutive prolines, such as PPG, PPP, or longer proline strings, in natural and engineered model proteins. EF-P promotes peptide-bond formation and stabilizes the peptidyl–transfer RNA in the catalytic center of the ribosome. EF-P is posttranslationally modified by a hydroxylated β-lysine attached to a lysine residue. The modification enhances the catalytic proficiency of the factor mainly by increasing its affinity to the ribosome. We propose that EF-P and its eukaryotic homolog, eIF5A, are essential for the synthesis of a subset of proteins containing proline stretches in all cells.

scholarly journals Orthoformimycin inhibits translation elongation by displacing the A-site tRNA and preventing peptide bond formation

2021 ◽  
Author(s):  
Andreas Schedlbauer ◽  
Tatsuya Kaminishi ◽  
Attilio Fabbretti ◽  
Pohl Milon ◽  
Xu Han ◽  
...  
Keyword(s):  
Ribosomal Subunit ◽  
Peptide Bond ◽  
Resistance Mechanisms ◽  
Peptide Bond Formation ◽  
Translation Elongation ◽  
X Ray Crystallography ◽  
Steady State Kinetics ◽  
A Site ◽  
Insight Into ◽  
Major Target

The ribosome is a major target for antibiotics owing to its essential cellular role in protein synthesis. Structural analysis of ribosome-antibiotic complexes provides insight into the molecular basis for their inhibitory action and highlights possible avenues to improve their potential or overcome existing resistance mechanisms. Here we use X-ray crystallography and pre-steady state kinetics to detail the inhibitory mechanism of the antimicrobial on the large ribosomal subunit.

scholarly journals Unwanted hydrolysis or α/β-peptide bond formation: how long should the rate-limiting coupling step take?

RSC Advances ◽  
2019 ◽  
Vol 9 (53) ◽  
pp. 30720-30728 ◽  
Author(s):  
Viktória Goldschmidt Gőz ◽  
Adrienn Nagy ◽  
Viktor Farkas ◽  
Ernő Keszei ◽  
András Perczel
Keyword(s):  
Amino Acids ◽  
Bond Formation ◽  
Side Reaction ◽  
Peptide Bond ◽  
Amide Bond ◽  
Peptide Bond Formation ◽  
Active Esters ◽  
Amide Bond Formation ◽  
Rate Limiting ◽  
Hydrolysis Of

Parallel to the amide bond formation, the hydrolysis of the active esters of α/β-amino acids, as an unwanted side reaction limiting coupling efficacy, is studied.

ONIOM and ab-initio calculations on the mechanism of uncatalyzed peptide bond formation

2012 ◽  
Vol 90 (6) ◽  
pp. 691-700 ◽  
Author(s):  
Hadieh Monajemi ◽  
Mohammad Noh Daud ◽  
Sharifuddin Mohd. Zain ◽  
Wan Ahmad Tajuddin Wan Abdullah
Keyword(s):  
Amino Acids ◽  
Bond Formation ◽  
Computational Cost ◽  
Peptide Bond ◽  
Peptide Bond Formation ◽  
Initiator Trna ◽  
Reduced Rate ◽  
Surface Scan ◽  
A Site

Finding a proper transition structure for the peptide bond formation process can lead one to a better understanding of the role of ribosome in catalyzing this reaction. Using computer simulations, we performed the potential energy surface scan on the ester bond dissociation of P-site aminoacyl-tRNA and the peptide bond formation of P-site and A-site amino acids. The full fragments of initiator tRNAimet and elongator tRNAphe are attached to both cognate and non-cognate amino acids as the P-site substrate. The A-site amino acid for all four calculations is methionine. We used ONIOM calculations to reduce the computational cost. Our study illustrates the reduced rate of peptide bond formation for misacylated tRNAimet in the absence of ribosomal bases. The misacylated elongator tRNAphe, however, did not show any difference in its PES compared with that for the phe-tRNAphe. This demonstrates the structural specification of initiator tRNAimet for the amino acids side chain.

scholarly journals Visualization of Trna Movements on the Escherichia coli 70s Ribosome during the Elongation Cycle

2000 ◽  
Vol 150 (3) ◽  
pp. 447-460 ◽  
Author(s):  
Rajendra K. Agrawal ◽  
Christian M.T. Spahn ◽  
Pawel Penczek ◽  
Robert A. Grassucci ◽  
Knud H. Nierhaus ◽  
...  
Keyword(s):  
Bond Formation ◽  
Three Dimensional ◽  
Peptide Bond ◽  
High Accuracy ◽  
Peptide Bond Formation ◽  
Elongation Cycle ◽  
Before And After ◽  
70S Ribosome ◽  
Similar Accuracy ◽  
A Site

Three-dimensional cryomaps have been reconstructed for tRNA–ribosome complexes in pre- and posttranslocational states at 17-Å resolution. The positions of tRNAs in the A and P sites in the pretranslocational complexes and in the P and E sites in the posttranslocational complexes have been determined. Of these, the P-site tRNA position is the same as seen earlier in the initiation-like fMet-tRNAfMet-ribosome complex, where it was visualized with high accuracy. Now, the positions of the A- and E-site tRNAs are determined with similar accuracy. The positions of the CCA end of the tRNAs at the A site are different before and after peptide bond formation. The relative positions of anticodons of P- and E-site tRNAs in the posttranslocational state are such that a codon–anticodon interaction at the E site appears feasible.

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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