Loss of N1-Methylation of G37 in tRNA Induces Ribosome Stalling and Reprograms Gene Expression
Ontology highlight
ABSTRACT:
ORGANISM(S): Escherichia coli str. K-12 substr. MG1655
PROVIDER: GSE165592 | GEO | 2021/08/19
REPOSITORIES: GEO
Similar Datasets
Project description:Diphthamide (DPH) is a conserved amino acid modification on eukaryotic translation elongation factor eEF2. We show that loss of DPH increases -1 ribosomal frameshifting at both programmed, including in SARS-CoV-2, and non-programmed sites. Ribosome profiling of yeast and mammalian cells lacking DPH reveals increased ribosomal drop-off during elongation. The drop-off defect on the long yeast MDN1 gene was suppressed by eliminating out-of-frame stop codons. Our data reveal that loss of DPH impairs the fidelity of translocation during translation elongation resulting in increased rates of ribosomal frameshifting and premature termination at out-of-frame stop codons.
2023-01-10 | GSE176169 | GEO
Project description:Mitochondria contain a specific translation machinery for the synthesis of respiratory chain components encoded on the mitochondrial genome. Mitochondrial tRNAs (mt-tRNAs) are also generated from the mitochondrial genome and, similar to their cytoplasmic counterparts, are modified at various positions. Here, we find that the RNA methyltransferase METTL8, is a mitochondrial protein that facilitates m3C methylation at position C32 of mt-tRNASer(UCN) and mt-tRNAThr. METTL8 knock out cells show reduced and over expressing cells enhanced respiratory chain activity. In pancreatic cancer, METTL8 levels are high, which correlates with patient survival. Indeed, METTL8 up regulation stimulates respiratory chain activity in these cells. Ribosome occupancy analysis using ribosome profiling revealed ribosome stalling on mt-tRNASer(UCN) and mt-tRNAThr codons and mass spectrometry analysis of native ribosomal subcomplexes unraveled reduced respiratory chain incorporation of the mitochondria encoded proteins ND6 and ND1. A well-balanced translation of mt-tRNASer(UCN) and mt-tRNAThr codons through METTL8-mediated C32 methylation might therefore provide optimal respiratory chain compositions and function.
2023-01-02 | GSE180400 | GEO
Project description:Upon initiation at an AUG start codon, the ribosome must maintain the correct reading frame for hundreds of codons in order to produce functional proteins. Although some sequence elements are able to trigger programmed ribosomal frameshifting (PRF), very little is known how the ribosome normally prevents spontaneous frameshift errors. Using high resolution ribosome profiling data sets, we discovered that the translating ribosome uses the 3’ end of 18S rRNA to scan the AUG-like codons after the decoding process. The internal mRNA:rRNA interaction not only contributes to predominant translational pausing, but also provides a post-decoding mechanism to safeguard the ribosome in the correct reading frame. Partially eliminating the AUG-like “sticky” codons in the reporter message leads to increased +1 frameshift errors. Remarkably, mutating the highly conserved CAU triplet of 18S rRNA globally changes codon “stickiness”. Further supporting the role of “sticky” sequences in reading frame maintenance, the codon composition of open reading frames is highly optimized across eukaryotic genomes by minimizing the appearance of AUG-like codons in the frame 2. These results suggest an important layer of information embedded within the protein coding sequences that instructs the ribosome to ensure reading frame fidelity during translation.
2016-04-12 | GSE80156 | GEO
Project description:Stalling of the ribosomes on the mRNA has been linked to myriad of molecular and biological functions. While a multitude of algorithms predict codon-usage in ribosome profiling data, no tool exists to predict the context-specific stalling of ribosomes on transcripts. Combining these two features can reveal unprecedented insights in the ribosomal function and their usage across cells and conditions. To overcome this lack of tools to comprehensively analyze these features, we created Bumpfinder, a web-server, that provides comprehensive analytical details on differences in total ribosome occupancy on transcripts, ribosomal occupancy across codons, ribosome-stalling and the underlying causal amino-acids/codons, as well as collisions. Employing Bumpfinder on generated and publicly available ribosome-profiling datasets, we studied the response of various cell types to amino-acid starvation conditions. We observed interesting patterns in response to the biological effects, suggesting the impact of quality control mechanisms of protein synthesis. Complimentary analysis of collided ribosomes demonstrated phased ribosome stalling on the identified sites. Thus, by deciphering context-specific ribosome distribution, Bumpfinder provides unprecedented molecular insights in the ribosome function and mRNA translation during stress response conditions.
2023-12-31 | GSE156443 | GEO
Project description:Post-transcriptional modifications are important for transfer RNAs (tRNAs) to be efficient and accurate in translation on the ribosome. The m1G37 modification on a subset of tRNAs in bacteria are generated by a conserved methyltransferase TrmD and is essential for bacterial growth. Previous studies showed that m1G37 has an important role in preventing translational frameshifting and also that this modification is coupled with aminoacylation of tRNAs for proline. Here we performed suppressor screening to isolate a mutant E. coli cell that lacks TrmD but is viable, and the whole-genome sequencing revealed several mutations on prolyl-tRNA synthetase (ProRS) gene conferring cell viability in the absence of TrmD. Biochemical assays confirmed uncoupling of m1G37 modification and aminoacylation, and cell-based assays uncovered the critical role of m1G37 in supporting Wobble decoding.
2022-09-24 | E-MTAB-12178 | biostudies-arrayexpress
Project description:Many tumors escape by activating multiple cellular pathways that induce immunosuppression. One pivotal immune-suppressive mechanism is the production of tryptophan metabolites along the kynurenine pathway by IFNγ-induced IDO1 enzyme production 4-8. Phase III clinical trials using chemical inhibition of IDO1 in combination with PD1 pathway blockade, however, failed to improve melanoma treatment 9-12. This points at an incomplete understanding of the role of IDO1 and the consequent tryptophan degradation on mRNA translation and cancer progression. Here, we investigated the effects of prolonged IFNγ treatment on mRNA translation in melanoma cells by ribosome profiling. Surprisingly, we observed a massive accumulation of ribosomes ~20 amino acids downstream of tryptophan codons (termed here as W-Bumps) along with their expected stalling at the tryptophan codon itself. This indicated ribosomal bypass of the tryptophan codons in the absence of tryptophan. Detailed examination of W-Bumps position and its corresponding peptide sequences pinpointed towards ribosomal frameshifting events and their effects in the ribosome exit tunnel. In particular, W-Bumps strength was associated with the disorderedness level of potential out-of-frame peptides predicted downstream of tryptophan codons. Indeed, reporter assays demonstrated the induction of ribosomal frameshifting, and the generation of trans-frame proteins and their presentation at the cell surface after IFNγ treatment. Proteomics and immunopeptidomics analyses verified the production of IFNγ-induced trans-frame and out-of-frame aberrant peptides and their presentation on HLA class I molecules. Priming of naïve T cells from healthy donors with aberrant peptides resulted in identification of reactive, peptide-specific T cells. Altogether, our results suggest that IFNγ-induced IDO1-mediated tryptophan depletion plays a role in the immune recognition of melanoma cells by contributing to the diversity of the peptidome landscape, and by inducing the presentation of aberrant peptides.
2020-12-04 | PXD020224 | Pride
Project description:Translation elongation rates are regulated to ensure proper conformation and biological function of proteins. Translation of either non-stop mRNA or transcripts coding for poly-basic sequences induces ribosome stalling, and the arrest product is degraded by the ribosome-mediated quality control system (RQC). During this process, the stalled ribosome is dissociated into subunits, and the polypeptide is ubiquitinated by the E3 ubiquitin ligase Listerin on the 60S large ribosomal subunit (LSU) leading to subsequent proteasomal degradation. However, it is largely unknown how stalled ribosomes are recognized and dissociated into subunits. Here we report that ubiquitination of the ribosomal protein uS10 by the E3 ubiquitin ligase Hel2 is required for the production of the RQC substrate. RQC-trigger (RQT) factors, a RNA helicase-family protein Slh1/Rqt2, ubiquitin binding protein Cue3/Rqt3 and yKR023W/Rqt4, were also required for the primary steps of RQC, and associated with Hel2-ribosome complexes. Rqt2-4 factors were dispensable for the ubiquitination of uS10 by Hel2/Rqt1 and associated with ribosomes independent of the ubiquitination of uS10. However, the ubiquitin-binding activity of Rqt3 were crucial to trigger RQC. Cryo-electron microscopy (cryo-EM) analysis revealed that Hel2 bound ribosomes are in an rotated state containing hybrid state AP- and PE-tRNAs. Furthermore, ribosome profiling revealed that short footprints, hallmarks of hybrid state ribosomes18, were accumulated at tandem CGA rare codons at the beginning of the poly arginine stalling sequence and long footprints at subsequent codons, respectively. Short footprints at CGA codons were decreased in rqt1 mutant but drastically increased in uS10 mutants defective in the ubiquitination or rqt2 mutant. Collectively, our results demonstrate that Hel2 stabilizes ratcheted ribosomes leading to ubiquitination of uS10. Subsequently, Rqt2-4 factors target these hybrid state ribosomes specifically, allowing subsequent RQC reactions.
2017-07-31 | GSE79622 | GEO
Project description:Protein synthesis by ribosomes takes place on a linear substrate but at variable speeds. Transient pausing of ribosomes can impact a variety of co-translational processes, including protein targeting and folding. These pauses are influenced by the sequence of the mRNA. Thus redundancy in the genetic code allows the same protein to be translated at different rates. However, our knowledge of both the position and the mechanism of translational pausing in vivo is highly limited. Here we present a genome-wide analysis of translational pausing in bacteria using ribosome profiling-deep sequencing of ribosome-protected mRNA fragments. This approach enables high-resolution measurement of ribosome density profiles along most transcripts at unperturbed, endogenous expression levels. Unexpectedly, we found that codons decoded by rare tRNAs do not lead to slow translation under nutrient-rich conditions. Instead, Shine-Dalgarno-(SD) like features within coding sequences cause pervasive translational pausing. Using an orthogonal ribosome possessing an altered anti-SD sequence, we demonstrated that pausing is due to hybridization between mRNA and the 16S rRNA of the translating ribosome. In protein coding sequences, internal SD sequences are disfavoured, which leads to biased usage, avoiding codons and codon pairs that resemble canonical SD sites. Our results indicate that internal SD-like sequences are a major determinant of translation rates and a global driving force for the coding of bacterial genomes. Identification of translation pause sites in vivo using ribosome profiling
2012-04-01 | E-GEOD-35641 | biostudies-arrayexpress
Project description:Programmed ribosomal frameshifting is the key event during translation of the SARS-CoV-2 RNA genome allowing synthesis of the viral RNA-dependent RNA polymerase and downstream viral proteins. Here we present the cryo-EM structure of the mammalian ribosome in the process of translating viral RNA paused in a conformation primed for frameshifting. We observe that the viral RNA adopts a pseudoknot structure lodged at the mRNA entry channel of the ribosome to generate tension in the mRNA that leads to frameshifting. The nascent viral polyprotein that is being synthesized by the ribosome paused at the frameshifting site forms distinct interactions with the ribosomal polypeptide exit tunnel. We use biochemical experiments to validate our structural observations and to reveal mechanistic and regulatory features that influence the frameshifting efficiency. Finally, a compound previously shown to reduce frameshifting is able to inhibit SARS-CoV-2 replication in infected cells, establishing coronavirus frameshifting as target for antiviral intervention.
2021-05-17 | GSE167421 | GEO
Project description:The tRNA pool determines the efficiency, throughput, and accuracy of translation. Previous studies have identified dynamic changes in the tRNA supply and mRNA demand during cancerous proliferation. Yet, dynamic changes may occur also during physiologically normal proliferation, and these are less characterized. We examined the tRNA and mRNA pools of T-cells during their vigorous proliferation and differentiation upon triggering of the T cell antigen receptor. We observe a global signature of switch in demand for codon at the early proliferation phase of the response, accompanied by corresponding changes in tRNA expression levels. In the later phase, upon differentiation of the T cells, the response of the tRNA pool is relaxed back to basal level, potentially restraining excessive proliferation. Sequencing of tRNAs allowed us to also evaluate their diverse base-modifications. We found that two types of tRNA modifications, Wybutosine and ms2t6A, are reduced dramatically during T-cell activation. These modifications occur in the anti-codon loops of two tRNAs that decode “slippery codons”, that are prone to ribosomal frameshifting. Attenuation of these frameshift-protective modifications is expected to increase proteome-wide frameshifting during T-cell proliferation. Indeed, human cell lines deleted of a Wybutosine writer showed increased ribosomal frameshifting, as detected with a reporter that consists of a critical frameshifting site taken from the HIV gag-pol slippery codon motif. These results may explain HIV’s specificity to proliferating T-Cells since it requires ribosomal frameshift exactly on this codon for infection. The changes in tRNA expression and modifications uncover a new layer of translation regulation during T-cell proliferation and exposes a potential trade-off between cellular growth and translation fidelity.
2021-10-13 | GSE165537 | GEO