A systematically-revised ribosome profiling protocol for bacteria reveals translational pauses at single-codon resolution
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ABSTRACT:
PROVIDER: PRJNA488109 | ENA |
REPOSITORIES: ENA
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Project description:In eukaryotes, ribosome profiling provides insight into the mechanism of protein synthesis at the codon level. In bacteria, however, the method has been more problematic and no consensus has emerged for how to best prepare profiling samples. Here, we identify the sources of these problems and describe new solutions for arresting translation and harvesting cells in order to overcome them. These improvements remove confounding artifacts and improve the resolution to allow analyses of ribosome behavior at the codon level. With a clearer view of the translational landscape in vivo, we observe that filtering cultures leads to translational pauses at serine and glycine codons through the reduction of tRNA aminoacylation levels. This observation illustrates how bacterial ribosome profiling studies can yield insight into the mechanism of protein synthesis at the codon level and how these mechanisms are regulated in response to changes in the physiology of the cell.
2019-02-08 | GSE119104 | GEO
Project description: Not available
| S-EPMC6377232 | biostudies-literature
Project description:In order to systematically assess the frequency and origin of stop codon recoding events, we designed a library of reporters. We introduced premature stop codons into mScarlet that enabled high-throughput quantification of protein synthesis termination errors in E. coli using fluorescent microscopy. We found that under stress conditions, stop codon recoding may occur with a rate as high as 80%, depending on the nucleotide context, suggesting that evolution frequently samples stop codon recoding events. The analysis of selected reporters by mass spectrometry and RNA-seq showed that not only translation but also transcription errors contribute to stop codon recoding. The RNA polymerase is more likely to misincorporate a nucleotide at premature stop codons. Proteome-wide detection of stop codon recoding by mass spectrometry revealed that temperature regulates the expression of cryptic sequences generated by stop codon recoding in E. coli. Overall, our findings suggest that the environment influences the accuracy of protein production which increases protein heterogeneity when the organisms need to adapt to new conditions.
2024-03-28 | GSE226936 | GEO
Project description:Stop codon recoding events give rise to longer proteins, which may alter the proteins function and thereby generate short-lasting phenotypic variability from a single gene.
In order to systematically assess the frequency and origin of recoding events, we designed a library of reporters. We introduced premature stop codons into mScarlet that enabled high-throughput quantification of protein synthesis termination errors in E.coli using fluorescent microscopy. We found that under stress conditions, stop codon recoding may occur as high as 80 percent of the time, depending on the genetic context, suggesting that evolution frequently samples stop codon recoding events. Targeted mass spectrometry and RNA-seq analyses showed that not only translational but also transcriptional errors contribute to stop codon recoding. The RNA polymerase is more likely to misincorporate a nucleotide at premature stop codons. Proteome-wide mass -spectrometry revealed that temperature regulates the expression of cryptic peptides generated by stop codon recoding in E.coli.
Overall, our findings suggest that the environment influences the accuracy of protein production which increases protein heterogeneity when the organisms need to adapt to new conditions.
2023-01-14 | MSV000091065 | MassIVE
Project description:Protein translation depends on mRNA-specific initiation, elongation, and termination rates. While the regulation of ribosome elongation is well studied in bacteria and yeast, less is known in higher eukaryotes. Here, we combined ribosome and tRNA profiling to investigate the relations between ribosome elongation rates, (aminoacyl-) tRNA levels and codon usage in mammals. We modeled codon-specific ribosome dwell times and translation fluxes from ribosome profiling, considering pair-interactions between ribosome sites. In mouse liver, the model revealed site and codon specific dwell times, as well as codon pair-interactions clustering by amino acids. While translation fluxes varied significantly across diurnal time and feeding regimen, codon dwell times were highly stable, and conserved in human. Fasting had no effect on codon dwell times in mouse liver. Profiling of total and aminoacylated tRNAs revealed highly heterogeneous levels with specific isoacceptor patterns and a correlation with codon usage. tRNAs for isoleucine, asparagine, aspartate and arginine were lowly loaded and conserved in fasted mice. Finally, codons with low levels of charged tRNAs and high codon usage relative to tRNA abundance exhibited long dwell times. Together, these analyses pave the way towards understanding the complex relation between tRNA loading, codon usage and ribosome dwell times in mammals.
2020-03-26 | GSE126383 | GEO
Project description:Codon usage bias is a universal feature of eukaryotic and prokaryotic genomes and has been proposed to regulate translation efficiency, accuracy and protein folding based on the assumption that codon usage affects translation dynamics. The role of codon usage in regulating translation, however, is not clear and has been challenged by recent ribosome profiling studies. Here we used a Neurospora cell-free translation system to directly monitor the velocity of mRNA translation. We demonstrated that the use of preferred codons enhances the rate of translation elongation, whereas non-optimal codons slow translation. In addition, codon usage regulates ribosome traffic on the mRNA. These conclusions were supported by ribosome profiling results in vitro and in vivo with substrate mRNAs manipulated to increase signal over background noise. We further show that codon usage plays an important role in regulating protein function by affecting co-translational protein folding. Together, these results resolve a long-standing fundamental question and demonstrate the importance of codon usage on protein folding.
2015-07-18 | GSE71032 | GEO
Project description:Protein translation depends on mRNA-specific initiation, elongation, and termination rates. While the regulation of ribosome elongation is well studied in bacteria and yeast, less is known in higher eukaryotes. Here, we combined ribosome and tRNA profiling to investigate the relations between ribosome elongation rates, (aminoacyl-) tRNA levels and codon usage in mammals. We modeled codon-specific ribosome dwell times and translation fluxes from ribosome profiling, considering pair-interactions between ribosome sites. In mouse liver, the model revealed site and codon specific dwell times, as well as codon pair-interactions clustering by amino acids. While translation fluxes varied significantly across diurnal time and feeding regimen, codon dwell times were highly stable, and conserved in human. Fasting had no effect on codon dwell times in mouse liver. Profiling of total and aminoacylated tRNAs revealed highly heterogeneous levels with specific isoacceptor patterns and a correlation with codon usage. tRNAs for isoleucine, asparagine, aspartate and arginine were lowly loaded and conserved in fasted mice. Finally, codons with low levels of charged tRNAs and high codon usage relative to tRNA abundance exhibited long dwell times. Together, these analyses pave the way towards understanding the complex relation between tRNA loading, codon usage and ribosome dwell times in mammals.
2020-03-26 | GSE126382 | GEO
Project description:Interest in exploiting algae as a biofuel source and the role of nutrient deficiency in inducing triacylglyceride (TAG) accumulation in cells necessitates a strategy to efficiently formulate species-specific culture media that can be easily manipulated. Using the reference organism Chlamydomonas reinhardtii, we tested the hypothesis that modeling trace element supplements on the ionomes of cells would result in optimized cell growth. We characterized the ionomes of multiple wild-type Chlamydomonas strains in various culture conditions and developed a revised trace element solution to parallel our measurements. Comparison of cells growing in the revised supplement versus a traditional trace element solution revealed faster growth rates and higher maximum cell densities with the revised recipe. RNA-seq analysis of cultures growing in the traditional versus revised medium suggest that the variation in transcriptomes was smaller than that found between laboratories using the same supplement. Visual observation did not reveal defects in cell motility or mating efficiency. Ni2+-inducible expression from the CYC6 promoter remained a useful tool, albeit with an increased amount of Ni2+ supplementation due to the introduction of an EDTA buffer system in the revised medium. Equilibrium modeling of the revised supplement predicts less metal precipitation in the revised medium. Other advantages include more facile preparation of trace element stock solutions that can readily be adapted for deficiency studies, a reduction in total chemical use, a more consistent batch-to-batch formulation, and long-term stability (up to 5 years). Under the new growth regime, we analyzed cells growing under different macro- and micronutrient-deficiencies. In N and S deficiency, cells accumulate TAG as well in the new medium as previously demonstrated. Fe and Zn deficiency also induced TAG accumulation as suggested by Nile Red and Bodipy staining. This ionomic approach can be used to efficiently optimize culturing conditions for other algal species to improve growth and assay cell physiology. Sampling of Chlamydomonas CC-1021 (2137) cultivated in TAP medium supplemented with a revised trace element recipe based on ionomic data.
2011-10-23 | E-GEOD-25622 | biostudies-arrayexpress
Project description:The aim of this study is to evaluate how cellular energy levels shape codon-specific decoding and affect codon-mediated mRNA degradation. To this end we made use of HT5P-seq (Zhang & Pelechano, 2021, PMID:35474692) in S. cerevisiae to footprint the ribosome of co-translationally degraded mRNAs in vivo upon swift changes in the concentration of intracellular ATP and other energy metabolites.
2024-03-08 | GSE216524 | GEO
Project description:Members of the third domain of life, the Archaea, are ubiquitous in all environments on Earth but remain understudied in many aspects including regulatory processes of the central dogma. Archaea present unique biology because they utilize a mosaic of molecular features from both Bacteria and Eukarya, along with unique features. The advent of a high-throughput view of the translation landscape via ribosome profiling in the Bacteria and the Eukarya has illuminated the complexity and previously underappreciated regulation of translation (i.e. translation efficiency, ribosome surveillance, etc.) that potentially has large scale effects on cellular functionality. Here, we developed ribosome profiling in a model archaeon, Haloferax volcanii and elucidated the translational landscape for the first time in the third domain of life. We coupled ribosome profiling with translation inhibitors to: (a) determine the size of the archaeal ribosome footprint, (b) systematically assign translation states of the ribosome to footprint lengths in a mostly leaderless transcriptome, (c) experimentally induce ribosome pauses and clarify the pausing landscape comprehensively, (d) identify putative novel proteins, including small open reading frames (smORFs), and (e) provide evidence that many genes initiate on putative alternative translation start sites (paTSS) around and within open reading frames (ORFs), demonstrating how a microorganism with a gene dense genome can produce proteins with distinct functions using the same gene.
2020-04-27 | GSE138990 | GEO