scholarly journals Ataluren and aminoglycosides stimulate read-through of nonsense codons by orthogonal mechanisms

2021 ◽  
Vol 118 (2) ◽  
pp. e2020599118
Author(s):  
Martin Y. Ng ◽  
Hong Li ◽  
Mikel D. Ghelfi ◽  
Yale E. Goldman ◽  
Barry S. Cooperman
Keyword(s):  
Protein Synthesis ◽  
Stop Codon ◽  
European Medicines Agency ◽  
Translation System ◽  
Release Factor ◽  
Factor Activity ◽  
Eukaryotic Translation ◽  
Nonsense Codons ◽  
Cognate Trna

During protein synthesis, nonsense mutations, resulting in premature stop codons (PSCs), produce truncated, inactive protein products. Such defective gene products give rise to many diseases, including cystic fibrosis, Duchenne muscular dystrophy (DMD), and some cancers. Small molecule nonsense suppressors, known as TRIDs (translational read-through–inducing drugs), stimulate stop codon read-through. The best characterized TRIDs are ataluren, which has been approved by the European Medicines Agency for the treatment of DMD, and G418, a structurally dissimilar aminoglycoside. Previously [1], we applied a highly purified in vitro eukaryotic translation system to demonstrate that both aminoglycosides like G418 and more hydrophobic molecules like ataluren stimulate read-through by direct interaction with the cell’s protein synthesis machinery. Our results suggested that they might do so by different mechanisms. Here, we pursue this suggestion through a more-detailed investigation of ataluren and G418 effects on read-through. We find that ataluren stimulation of read-through derives exclusively from its ability to inhibit release factor activity. In contrast, G418 increases functional near-cognate tRNA mispairing with a PSC, resulting from binding to its tight site on the ribosome, with little if any effect on release factor activity. The low toxicity of ataluren suggests that development of new TRIDs exclusively directed toward inhibiting termination should be a priority in combatting PSC diseases. Our results also provide rate measurements of some of the elementary steps during the eukaryotic translation elongation cycle, allowing us to determine how these rates are modified when cognate tRNA is replaced by near-cognate tRNA ± TRIDs.

scholarly journals Nsp1 of SARS-CoV-2 Stimulates Host Translation Termination

2020 ◽  
Author(s):  
Alexey Shuvalov ◽  
Ekaterina Shuvalova ◽  
Nikita Biziaev ◽  
Elizaveta Sokolova ◽  
Konstantin Evmenov ◽  
...  
Keyword(s):  
Stop Codon ◽  
Translation Termination ◽  
Translation System ◽  
Release Factor ◽  
Viral Mrnas ◽  
Codon Recognition ◽  
Free Translation ◽  
Stop Codon Recognition ◽  
A Cell

ABSTRACTThe Nsp1 protein of SARS-CoV-2 regulates the translation of host and viral mRNAs in cells. Nsp1 inhibits host translation initiation by occluding the entry channel of the 40S ribosome subunit. The structural study of SARS-CoV-2 Nsp1-ribosomal complexes reported post-termination 80S complex containing Nsp1 and the eRF1 and ABCE1 proteins. Considering the presence of Nsp1 in the post-termination 80S ribosomal complex simultaneously with eRF1, we hypothesized that Nsp1 may be involved in translation termination. Using a cell-free translation system and reconstituted in vitro translation system, we show that Nsp1 stimulates translation termination in the stop codon recognition stage at all three stop codons. This stimulation targets the release factor 1 (eRF1) and does not affect the release factor 3 (eRF3). The activity of Nsp1 in translation termination is provided by its N-terminal domain and the minimal required part of eRF1 is NM domain. We assume that biological meaning of Nsp1 activity in translation termination is binding with the 80S ribosomes translating host mRNAs and removal them from the pool of the active ribosomes.

scholarly journals Eukaryotic Release Factor 1 Phosphorylation by CK2 Protein Kinase Is Dynamic but Has Little Effect on the Efficiency of Translation Termination in Saccharomyces cerevisiae

2006 ◽  
Vol 5 (8) ◽  
pp. 1378-1387 ◽  
Author(s):  
Adam K. Kallmeyer ◽  
Kim M. Keeling ◽  
David M. Bedwell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Synthesis ◽  
Protein Kinase ◽  
Stop Codon ◽  
Translation Termination ◽  
Release Factor ◽  
Codon Recognition ◽  
Number Of Factors ◽  
Stop Codon Recognition

ABSTRACT Protein synthesis requires a large commitment of cellular resources and is highly regulated. Previous studies have shown that a number of factors that mediate the initiation and elongation steps of translation are regulated by phosphorylation. In this report, we show that a factor involved in the termination step of protein synthesis is also subject to phosphorylation. Our results indicate that eukaryotic release factor 1 (eRF1) is phosphorylated in vivo at serine 421 and serine 432 by the CK2 protein kinase (previously casein kinase II) in the budding yeast Saccharomyces cerevisiae. Phosphorylation of eRF1 has little effect on the efficiency of stop codon recognition or nonsense-mediated mRNA decay. Also, phosphorylation is not required for eRF1 binding to the other translation termination factor, eRF3. In addition, we provide evidence that the putative phosphatase Sal6p does not dephosphorylate eRF1 and that the state of eRF1 phosphorylation does not influence the allosuppressor phenotype associated with a sal6Δ mutation. Finally, we show that phosphorylation of eRF1 is a dynamic process that is dependent upon carbon source availability. Since many other proteins involved in protein synthesis have a CK2 protein kinase motif near their extreme C termini, we propose that this represents a common regulatory mechanism that is shared by factors involved in all three stages of protein synthesis.

scholarly journals CTELS: A Cell-Free System for the Analysis of Translation Termination Rate

Biomolecules ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 911 ◽  
Author(s):  
Kseniya A. Lashkevich ◽  
Valeriya I. Shlyk ◽  
Artem S. Kushchenko ◽  
Vadim N. Gladyshev ◽  
Elena Z. Alkalaeva ◽  
...  
Keyword(s):  
Stop Codon ◽  
Translation Termination ◽  
Protein Biosynthesis ◽  
Inhibitory Effect ◽  
In Vitro Translation ◽  
Nonsense Suppression ◽  
Translation System ◽  
Free System ◽  
Termination Rate

Translation termination is the final step in protein biosynthesis when the synthesized polypeptide is released from the ribosome. Understanding this complex process is important for treatment of many human disorders caused by nonsense mutations in important genes. Here, we present a new method for the analysis of translation termination rate in cell-free systems, CTELS (for C-terminally extended luciferase-based system). This approach was based on a continuously measured luciferase activity during in vitro translation reaction of two reporter mRNA, one of which encodes a C-terminally extended luciferase. This extension occupies a ribosomal polypeptide tunnel and lets the completely synthesized enzyme be active before translation termination occurs, i.e., when it is still on the ribosome. In contrast, luciferase molecule without the extension emits light only after its release. Comparing the translation dynamics of these two reporters allows visualization of a delay corresponding to the translation termination event. We demonstrated applicability of this approach for investigating the effects of cis- and trans-acting components, including small molecule inhibitors and read-through inducing sequences, on the translation termination rate. With CTELS, we systematically assessed negative effects of decreased 3′ UTR length, specifically on termination. We also showed that blasticidin S implements its inhibitory effect on eukaryotic translation system, mostly by affecting elongation, and that an excess of eRF1 termination factor (both the wild-type and a non-catalytic AGQ mutant) can interfere with elongation. Analysis of read-through mechanics with CTELS revealed a transient stalling event at a “leaky” stop codon context, which likely defines the basis of nonsense suppression.

scholarly journals Identification of Mimotope Peptides Which Bind to the Mycotoxin Deoxynivalenol-Specific Monoclonal Antibody

1999 ◽  
Vol 65 (8) ◽  
pp. 3279-3286 ◽  
Author(s):  
Qiaoping Yuan ◽  
James J. Pestka ◽  
Brandon M. Hespenheide ◽  
Leslie A. Kuhn ◽  
John E. Linz ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Alkaline Phosphatase ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Synthetic Peptide ◽  
Amino Acid Sequences ◽  
In Vitro Translation ◽  
Enzyme Linked Immunosorbent Assay ◽  
Translation System

ABSTRACT Monoclonal antibody 6F5 (mAb 6F5), which recognizes the mycotoxin deoxynivalenol (DON) (vomitoxin), was used to select for peptides that mimic the mycotoxin by employing a library of filamentous phages that have random 7-mer peptides on their surfaces. Two phage clones selected from the random peptide phage-displayed library coded for the amino acid sequences SWGPFPF and SWGPLPF. These clones were designated DONPEP.2 and DONPEP.12, respectively. The results of a competitive enzyme-linked immunosorbent assay (ELISA) suggested that the two phage displayed peptides bound to mAb 6F5 specifically at the DON binding site. The amino acid sequence of DONPEP.2 plus a structurally flexible linker at the C terminus (SWGPFPFGGGSC) was synthesized and tested to determine its ability to bind to mAb 6F5. This synthetic peptide (designated peptide C430) and DON competed with each other for mAb 6F5 binding. When translationally fused with bacterial alkaline phosphatase, DONPEP.2 bound specifically to mAb 6F5, while the fusion protein retained alkaline phosphatase activity. The potential of using DONPEP.2 as an immunochemical reagent in a DON immunoassay was evaluated with a DON-spiked wheat extract. When peptide C430 was conjugated to bovine serum albumin, it elicited antibody specific to peptide C430 but not to DON in both mice and rabbits. In an in vitro translation system containing rabbit reticulocyte lysate, synthetic peptide C430 did not inhibit protein synthesis but did show antagonism toward DON-induced protein synthesis inhibition. These data suggest that the peptides selected in this study bind to mAb 6F5 and that peptide C430 binds to ribosomes at the same sites as DON.

Dosage effect of minor arginyl- and isoleucyl-tRNAs on protein synthesis in an Escherichia coli in vitro coupled transcription/translation system

2001 ◽  
Vol 91 (1) ◽  
pp. 53-57 ◽  
Author(s):  
Xiuping Jiang ◽  
Hideo Nakano ◽  
Takanori Kigawa ◽  
Takashi Yabuki ◽  
Shigeyuki Yokoyama ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Dosage Effect ◽  
Translation System

Identification of amino acids responsible for stop codon recognition for polypeptide chain release factor

2013 ◽  
Vol 91 (3) ◽  
pp. 155-164 ◽  
Author(s):  
Lijun Xu ◽  
Yanrong Hao ◽  
Cui Li ◽  
Quan Shen ◽  
Baofeng Chai ◽  
...  
Keyword(s):  
Stop Codon ◽  
Translation Termination ◽  
Release Factor ◽  
Codon Reassignment ◽  
Eukaryotic Translation ◽  
Codon Recognition ◽  
Terminal Domain ◽  
Class 1 ◽  
Stop Codon Recognition ◽  
Stop Codon Reassignment

One factor involved in eukaryotic translation termination is class 1 release factor in eukaryotes (eRF1), which functions to decode stop codons. Variant code species, such as ciliates, frequently exhibit altered stop codon recognition. Studies revealed that some class-specific residues in the eRF1 N-terminal domain are responsible for stop codon reassignment in ciliates. Here, we investigated the effects on stop codon recognition of chimeric eRF1s containing the N-terminal domain of Euplotes octocarinatus and Blepharisma japonicum eRF1 fused to Saccharomyces cerevisiae M and C domains using dual luciferase read-through assays. Mutation of class-specific residues in different eRF1 classes was also studied to identify key residues and motifs involved in stop codon decoding. As expected, our results demonstrate that 3 pockets within the eRF1 N-terminal domain were involved in decoding stop codon nucleotides. However, allocation of residues to each pocket was revalued. Our data suggest that hydrophobic and class-specific surface residues participate in different functions: modulation of pocket conformation and interaction with stop codon nucleotides, respectively. Residues conserved across all eRF1s determine the relative orientation of the 3 pockets according to stop codon nucleotides. However, quantitative analysis of variant ciliate and yeast eRF1 point mutants did not reveal any correlation between evolutionary conservation of class-specific residues and termination-related functional specificity and was limited in elucidating a detailed mechanism for ciliate stop codon reassignment. Thus, based on isolation of suppressor tRNAs from Euplotes and Tetrahymena, we propose that stop codon reassignment in ciliates may be controlled by cooperation between eRF1 and suppressor tRNAs.

Isoproterenol induces a ribosomal modification in the heart and the skeletal muscle of hamsters

1985 ◽  
Vol 5 (1) ◽  
pp. 13-19
Author(s):  
Josette Noël ◽  
Léa Brakier-Gingras
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Magnesium Concentration ◽  
Translation System ◽  
Synthesis Activity ◽  
And Control

The protein synthesis activity of heart, skeletal muscle and liver polysomes from isoprotenerol-treated and control hamsters has been compared in an in vitro non-inititating translation system. Heart and skeletal muscle polysomes from treated hamsters were less active than controls and required a higher magnesium concentration for optimal protein synthesis. These results suggest that there is a conformational modification in heart and skeletal muscle ribosomes from isoprotenerol-treated hamsters. No such change was observed with ribosomes from the liver of isoproterenol-treated hamsters.

scholarly journals Studies on the translation mechanism of subgenomic RNA of potato leafroll virus.

1997 ◽  
Vol 44 (1) ◽  
pp. 69-77 ◽  
Author(s):  
M Juszczuk ◽  
W Zagórski-Ostoja ◽  
D M Hulanicka
Keyword(s):  
Stop Codon ◽  
In Vitro Transcription ◽  
Open Reading Frames ◽  
Translation System ◽  
Translation Efficiency ◽  
Subgenomic Rna ◽  
Expression Of Genes ◽  
Initiation Of Translation ◽  
Leafroll Virus

The expression of open reading frames located on the subgenomic RNA (sgRNA) has been studied in an in vitro transcription and translation system. The obtained results indicate: a) translation of sgRNA occurs according to the scanning model since the insertion of palindrome (delta G0 = -61 kcal/mol) prevents the initiation of translation; b) ORF6 is translated by suppression of the stop codon separating ORF4 from ORF6 and the presence of suppressor tRNA is necessary for the readthrough; c) the presence of leader sequence of sgRNA (212 nucleotides) decreases the translation efficiency of ORFs located downstream and it affects the ratio of products of ORF4 and ORF5; d) 3'UTR does not influence on an expression of genes located on the sgRNA.

Protein 4.1R binding to eIF3-p44 suggests an interaction between the cytoskeletal network and the translation apparatus

Blood ◽  
2000 ◽  
Vol 96 (2) ◽  
pp. 747-753 ◽  
Author(s):  
Chia-Lung Hou ◽  
Chieh-ju C. Tang ◽  
Steve R. Roffler ◽  
Tang K. Tang
Keyword(s):  
Translation Initiation ◽  
Protein Translation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Translation System ◽  
Cdna Clones ◽  
Eukaryotic Translation ◽  
Translation Apparatus ◽  
Direct Association

Erythroid protein 4.1 (4.1R) is an 80-kd cytoskeletal protein that stabilizes the membrane-skeletal network structure underlying the lipid bilayer. Using the carboxyl terminal domain (22/24 kd) of 4.1R as bait in a yeast 2-hybrid screen, we isolated cDNA clones encoding a polypeptide of eIF3-p44, which represents a subunit of a eukaryotic translation initiation factor 3 (eIF3) complex. The eIF3 complex consists of at least 10 subunits that play an essential role in the pathway of protein translation initiation. Northern blot analysis revealed that eIF3-p44 (approximately 1.35 kb) is constitutively expressed in many tissues. The essential sequence for this interaction was mapped to the carboxyl-terminus of 4.1R (residues 525-622) and a region (residues 54-321) of eIF3-p44. The direct association between 4.1R and eIF3-p44 was further confirmed by in vitro binding assays and coimmunoprecipitation studies. To characterize the functions of eIF3-p44, we depleted eIF3-p44 from rabbit reticulocyte lysates either by anti-eIF3-p44 antibody or by GST/4.1R-80 fusion protein. Our results show that the eIF3-p44 depleted cell-free translation system was unable to synthesize proteins efficiently. The direct association between 4.1R and elF3-p44 suggests that 4.1R may act as an anchor protein that links the cytoskeleton network to the translation apparatus.

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