Nuclease-mediated depletion biases in ribosome footprint profiling libraries
Ontology highlight
ABSTRACT: Ribosome footprint profiling is a high throughput sequencing based technique that provides detailed and global views of translation in living cells. An essential part of this technology is removal of unwanted, normally abundant, ribosomal RNA sequences in order to save on sequencing costs. The most effective commercial solution (Ribo-Zero) has been discontinued and a number of new, experimentally distinct commercial applications have emerged on the market. Here we evaluated several commercially available alternatives designed for RNA-seq of human samples and find them unsuitable for ribosome footprint profiling. We instead recommend the use of custom-designed biotinylated oligos, which were widely used in early ribosome profiling studies. Importantly, we warn that depletion solutions based on targeted nuclease cleavage significantly perturb the high-resolution information that can be derived from the data, and thus do not recommend their use for any applications that require precise determination of the ends of RNA fragments.
Project description:Nucleases, i.e. enzymes that catalyze the hydrolysis of phosphodiester bonds in nucleic acids, are essential tools in molecular biology and biotechnology. Staphylococcus aureus nuclease (MNase) is particularly interesting due to its thermostability and Ca2+-dependence, making it the prime choice for applications where nuclease modulation is critical, such as ribosome profiling in bacteria and halophilic archaea. The latter poses a technical and economical challenge, as high salt reaction conditions negatively impact MNase activity, necessitating large amounts of nuclease to be used for achieving efficient cleavage. Here, we set out to generate an optimized production protocol for two forms of MNase — fully processed MNaseA and the 19 aa propeptide containing MNaseB — and to biochemically benchmark them against a commercial nuclease. Our results show that both MNases are highly active in normal reaction conditions, but MNaseA maintains higher enzymatic activity in high salt concentrations than MNaseB. MNaseA also retains >90% of its activity after multiple freeze-thaw cycles when stored at -80°C in a buffer containing 5% glycerol. Importantly, ribosome profiling experiments in Haloferax volcanii demonstrated that MNaseA produces ribosome footprints highly comparable to those obtained with the commercial nuclease, making it a suitable alternative for high-salt ribosome profiling applications. In conclusion, our method can be easily implemented for efficient MNaseA production, thereby providing access to an effective, robust, and cost-efficient alternative to commercial nucleases, as well as facilitating future translation studies into halophilic organisms.
2024-06-22 | GSE269836 | GEO
Project description:Ribosome Footprint Profiling of GIGYF2/EIF4E2 ko
Project description:Ribosome-footprint profiling provides genome-wide snapshots of translation, but technical challenges can confound its analysis. Here, we use improved methods to obtain ribosome-footprint profiles and mRNA abundances that more faithfully reflect gene expression in Saccharomyces cerevisiae. Our results support proposals that both the beginning of coding regions and codons matching rare tRNAs are more slowly translated. They also indicate that emergent polypeptides with as few as three basic residues within a 10-residue window tend to slow translation. With the improved mRNA measurements, the variation attributable to translational control in exponentially growing yeast was less than previously reported, and most of this variation could be predicted with a simple model that considered mRNA abundance, upstream open reading frames, cap-proximal structure and nucleotide composition, and lengths of the coding and 5'-untranslated regions. Collectively, our results provide a framework for executing and interpreting ribosome-profiling studies and reveal key features of translational control in yeast. Ribosome-footprint profiling and RNA-seq (total RNA, poly(A) selected, RiboMinus treated, or Ribo-Zero treated) from log-phase S. cerevisiae. The study includes a reanalysis of the two Samples from GSE53313. The reanalyzed data is linked to the Series record.
Project description:We analyzed the effect of deleting the gene encoding putative RNA helicase DBP1 in budding yeast on translational efficiencies (TEs) genome wide in wild-type or ded1-ts (temperature-sensitive allele of DED1) strains by combining ribosome footprint profiling with RNA-seq analysis of mRNA abundance. This study includes a total of 32 samples comprised of 16 RNA-Seq samples (mRNA) and 16 ribosome footprint profiling samples (ribo). Experiment 1 includes 8 samples, comprised of 4 RNA-Seq samples and 4 ribosome footprint profiling samples, derived from 2 biological replicates each of the dbp1Δ and ded1-ts dbp1Δ mutant strains, cultured in synthetic complete (SC) medium, following shifts in growth temperature from 30°C to 37°C for 2h. Experiment 2 examines the effect of overexpression of DBP1 in rescuing genome-wide translational defects of a ded1-cs mutant (cold-sensitive allele of DED1) and includes 12 samples, 6 RNA-Seq samples and 6 ribosome footprint profiling samples, derived from 2 biological replicates each of WT DED1 (dubbed DED1-CS), ded1-cs and ded1-cs overexpressing DBP1 (ded1-cs_hcDBP1) strains, cultured in SC-Leu-His medium, following shifts in growth temperature from 30°C to 15°C for 10 min. Experiment 3 examines rescue of translational defects of ded1-ts by DBP1 overexpression and includes 12 samples, 6 RNA-Seq samples and 6 ribosome footprint profiling samples, derived from 2 biological replicates each of WT DED1(DED1-TS), ded1-ts and ded1-ts overexpressing DBP1 (ded1-ts_hcDBP1) strains, cultured in SC-Leu-His medium, following shifts in growth temperature from 30°C to 37°C for 2h.
Project description:Ribosome profiling is a widespread tool for studying translational dynamics in human cells. Its central assumption is that ribosome footprint density on a transcript quantitatively reflects protein synthesis. Here, we test this assumption using pulsed-SILAC (pSILAC) high-accuracy targeted proteomics. We focus on multiple myeloma cells exposed to bortezomib, a first-line chemotherapy and proteasome inhibitor. In the absence of drug effects, we found that direct measurement of protein synthesis by pSILAC correlated well with indirect measurement of synthesis from ribosome footprint density. This correlation, however, broke down under bortezomib-induced stress. By developing a statistical model integrating longitudinal proteomic and mRNA-seq measurements, we found that proteomics could directly detect global alterations in translational rate caused by bortezomib; these changes are not detectable by ribosomal profiling alone. Further, by incorporating pSILAC data into a gene expression model, we predict cell-stress specific proteome remodeling events. These results demonstrate that pSILAC provides an important complement to ribosome profiling in measuring proteome dynamics. Timecourse experiment with six points over 48hr after bortezomib exposure in MM.1S myeloma cells. mRNA-seq and ribosome profiling data at each time point.
Project description:Ribosome profiling measures genome-wide translation dynamics at sub-codon resolution. Cycloheximide (CHX), a widely used translation inhibitor to arrest ribosomes in these experiments, has been shown to induce biases in yeast, questioning its use. However, whether such biases are present in datasets of other organisms including humans is unknown. Here we compare different CHX-treatment conditions in human cells and yeast in parallel experiments using an optimized protocol. We find that human ribosomes are not susceptible to conformational restrictions by CHX, nor does it distort gene-level measurements of ribosome occupancy, measured decoding speed or the translational ramp. Furthermore, CHX-induced codon-specific biases on ribosome occupancy are not detectable in human cells or other model organisms. This shows that reported biases of CHX are species-specific and that CHX does not affect the outcome of ribosome profiling experiments in most settings. Our findings provide a solid framework to conduct and analyze ribosome profiling experiments.
Project description:Ribosome profiling is a widespread tool for studying translational dynamics in human cells. Its central assumption is that ribosome footprint density on a transcript quantitatively reflects protein synthesis. Here, we test this assumption using pulsed-SILAC (pSILAC) high-accuracy targeted proteomics. We focus on multiple myeloma cells exposed to bortezomib, a first-line chemotherapy and proteasome inhibitor. In the absence of drug effects, we found that direct measurement of protein synthesis by pSILAC correlated well with indirect measurement of synthesis from ribosome footprint density. This correlation, however, broke down under bortezomib-induced stress. By developing a statistical model integrating longitudinal proteomic and mRNA-seq measurements, we found that proteomics could directly detect global alterations in translational rate caused by bortezomib; these changes are not detectable by ribosomal profiling alone. Further, by incorporating pSILAC data into a gene expression model, we predict cell-stress specific proteome remodeling events. These results demonstrate that pSILAC provides an important complement to ribosome profiling in measuring proteome dynamics.
Project description:During translation elongation, the ribosome ratchets along its mRNA template, incorporating each new amino acid and translocating from one codon to the next. The elongation cycle requires dramatic structural rearrangements of the ribosome. We show here that deep sequencing of ribosome-protected mRNA fragments reveals not only the position of each ribosome but also, unexpectedly, its particular stage of the elongation cycle. Sequencing reveals two distinct populations of ribosome footprints, 28-30 nucleotides and 20-22 nucleotides long, representing translating ribosomes in distinct states, differentially stabilized by specific elongation inhibitors. We find that the balance of small and large footprints varies by codon and is correlated with translation speed. The ability to visualize conformational changes in the ribosome during elongation, at single-codon resolution, provides a new way to study the detailed kinetics of translation and a new probe with which to identify the factors that affect each step in the elongation cycle. Ribosome profiling, or sequencing of ribosome-protected mRNA fragments, in yeast. We assay ribosome footprint sizes and positions in three conditions: untreated yeast (3 replicates) and yeast treated with translation inhibitors cycloheximide (2 replicates) and anisomycin (2 biological replicates, one technical replicate). We also treat yeast with 3-aminotriazole to measure the effect of limited histidine tRNAs on ribosome footprint size and distribution (two treatment durations).
Project description:Here, we use ribosome-footprint profiing and mRNA-seq to determine the average ribosome density on each gene in S. cerevisiae. We then perform quantitative modeling to identify the molecular determinants of ribosome density. Analysis of S. cerevisiae