Sensing of individual stalled 80S ribosomes by Fap1 for non-functional rRNA turnover. Li et al
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ABSTRACT:
PROVIDER: PRJNA668372 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR12804100.fastq.gz | Fastqsanger.gz | |||
| SRR12804101.fastq.gz | Fastqsanger.gz | |||
| SRR12804082.fastq.gz | Fastqsanger.gz | |||
| SRR12804083.fastq.gz | Fastqsanger.gz | |||
| SRR12804084.fastq.gz | Fastqsanger.gz |
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Project description:Cells can respond to stalled ribosomes by sensing ribosome collisions and employing quality control pathways. How ribosome stalling is resolved without collisions, however, has remained elusive. Here, focusing on non-colliding stalling exhibited by decoding-defective ribosomes, we identified Fap1 as a stalling sensor triggering 18S non-functional rRNA decay via poly-ubiquitination of uS3. Ribosome profiling revealed an enrichment of Fap1 at the translation initiation site but also association with elongating individual ribosomes. Cryo-EM structures of Fap1-bound ribosomes elucidated Fap1 probing the mRNA simultaneously at both the entry and exit channels suggesting a mRNA stasis sensing activity, and Fap1 sterically hinders formation of canonical collided di-ribosomes. Our findings indicate that individual stalled ribosomes are the potential signal for ribosome dysfunction, leading to accelerated turnover of the ribosome itself.
2022-09-15 | GSE159329 | GEO
Project description:Translational regulation at the stage of initiation impacts the number of ribosomes translating each mRNA molecule. For example, multiple ribosomes can engage on a single mRNA forming a polysome, resulting in highly efficient protein synthesis. However, the translational activity of single 80S ribosomes on mRNA (monosomes) is less well understood, even though these 80S monosomes represent the dominant ribosomal complexes in many tissues. Here, we used cryo-EM to determine the translational activity of 80S monosomes across different tissues in Drosophila melanogaster. We discovered that while head and embryo 80S monosomes are highly translationally active, testis and ovary 80S monosomes are translationally inactive. RNA-Seq analysis of head monosome- and polysome-translated mRNAs, revealed that head 80S monosomes preferentially translate mRNAs with TOP motifs, short 5’-UTRs, short ORFs and are enriched for uORFs. Overall, these findings highlight that regulation of translation initiation, and therefore the number of ribosomes bound per mRNA, varies substantially across tissues.
2025-03-24 | GSE267425 | GEO
Project description:Ribosome stalling at problematic sequences in mRNAs leads to collisions that trigger a collection of quality control events including ribosome rescue, targeting the nascent polypeptide for decay (Ribosome-mediated Quality Control or RQC), and targeting of the mRNA for decay (No Go Decay or NGD). Using a reverse genetic screen in yeast, we identify Cue2 as the endonuclease that is recruited to stalled ribosomes to promote NGD. Following Cue2-mediated cleavage, ribosomes upstream of the cleavage site translate to the end of the truncated mRNA and are rescued by the Dom34:Hbs1 complex. We also show that the putative helicase Slh1 (part of the RQC Trigger or RQT complex) removes collided ribosomes behind the lead stalled ribosome and thereby reduces endonucleolytic cleavage by Cue2. The synergistic activities of Cue2 and Slh1 define two parallel pathways that allow cells to recognize and respond to ribosomes trapped on problematic mRNAs.
2019-06-25 | GSE129128 | GEO
Project description:ZAKα Recognizes Stalled Ribosomes through Partially Redundant Sensor Domains
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Project description:eIF3 is a multi-subunit complex thought to execute numerous functions in canonical translation initiation, including mRNA recruitment to the 40S ribosome, scanning for the start codon, and inhibition of 60S subunit joining 1–3. eIF3 was also found to interact with 40S and 60S ribosomal proteins and translation elongation factors 4, but a direct involvement in translation elongation has never been demonstrated. Using selective ribosome profiling, we made the unexpected observation that eIF3 remains bound to post-initiation 80S ribosomes, followed by release after translation of ~50 codons. Furthermore, eIF3 deficiency reduces early ribosomal elongation speed, particularly on mRNAs encoding proteins associated with membrane-associated functions, resulting in defective synthesis of their encoded proteins and abnormal mitochondrial and lysosomal physiology. Accordingly, heterozygous eIF3e+/- knockout mice accumulate giant mitochondria in skeletal muscle and show a progressive decline in muscle strength with age. Hence, in addition to its canonical role in translation initiation, eIF3 interacts with 80S ribosomes to enhance, at the level of early elongation, the synthesis of proteins with membrane-associated functions, an activity that is critical for normal muscle health.
2020-06-15 | GSE149697 | GEO
Project description:The Gcn pathway is conserved in all eukaryotes, including mammals such as humans, where it is a crucial part of the integrated stress response (ISR). Gcn1 serves as an essential effector protein for the kinase Gcn2, which in turn is activated by stalled ribosomes, leading to phosphorylation of eIF2 and a subsequent global repression of translation. The fine-tuning of this adaptive response is performed by the Rbg2/Gir2 complex, a negative regulator of Gcn2. Despite the wealth of available biochemical data, information on structures of Gcn proteins on the ribosome has remained elusive. Here we present a cryo-electron microscopy structure of the yeast Gcn1 protein in complex with stalled and colliding 80S ribosomes. Gcn1 interacts with both 80S ribosomes within the disome, such that the Gcn1 HEAT repeats span from the P-stalk region on the colliding ribosome to the P-stalk and the A-site region of the lead ribosome. The lead ribosome is stalled in a nonrotated state with peptidyl-tRNA in the A-site, uncharged tRNA in the P-site, eIF5A in the E-site, and Rbg2/Gir2 in the A-site factor binding region. By contrast, the colliding ribosome adopts a rotated state with peptidyl-tRNA in a hybrid A/P-site, uncharged-tRNA in the P/E-site, and Mbf1 bound adjacent to the mRNA entry channel on the 40S subunit. Collectively, our findings reveal the interaction mode of the Gcn2-activating protein Gcn1 with colliding ribosomes and provide insight into the regulation of Gcn2 activation. The binding of Gcn1 to a disome has important implications not only for the Gcn2-activated ISR, but also for the general ribosome-associated quality control pathways.
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Project description:Ribosomal RNA modifications are introduced during ribosome assembly by snoRNA and stand-alone modification enzyme based mechanisms in budding yeast. Lack of individual modifications in rRNA has a minor effect on yeast growth, ribosome biogenesis, and translation, which has complicated the definition of the biological function of rRNA modifications. We have constructed a S.cerevisiae strain lacking 7 25S rRNA modifications (Ψ2826, Um2921, Gm2619, m5C2870, Ψ2880, Um2724 and Gm2922)in peptidyl-transferase center. This strain exhibits severely compromised growth at 30°C, reduced level of global translation and actively translating ribosomes and cold sensitivity. Ribosomal protein composition of the mature 80S ribosomes was analyzed by SILAC based qMS approach. We have found that absence of PTC modifications around PTC does not affect significantly r-protein content of 80S ribosomes.
2024-06-23 | PXD051211 | Pride
Project description:Cue2 and Slh1 define parallel pathways to rescue stalled ribosomes
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Project description:Fully assembled ribosomes exist in two populations: polysomes and monosomes. While the former has been studied extensively, to what extent translation occurs on monosomes and its importance for overall translational output remains controversial. Here, we used ribosome profiling to examine the translational status of 80S monosomes in Saccharomyces cerevisiae. We found that the vast majority of 80S monosomes are elongating, not initiating. Further, most mRNAs exhibit some degree of monosome occupancy, with monosomes predominating on nonsense-mediated decay (NMD) targets, upstream open reading frames (uORFs), canonical ORFs shorter than ~590 nucleotides and ORFs for which the total time required to complete elongation is substantially shorter than that required for initiation. Importantly, mRNAs encoding low-abundance regulatory proteins tend to be enriched in the monosome fraction. Our data highlight the importance of monosomes for the translation of highly regulated mRNAs. We examined the translational status of single 80S ribosomes using ribosome profiling, and compared these monosome footprints to both polysome ribosome footprints and general ribosome profiling. RNASeq libraries were also prepared from the overall sample input.
2016-02-11 | E-GEOD-76117 | biostudies-arrayexpress
Project description:Impairment of translation can lead to stalling and collision of ribosomes which constitute an activation platform for several ribosomal stress-surveillance pathways. Among these is the Ribotoxic Stress Response (RSR), where ribosomal sensing by the MAP3K ZAKa leads to activation of p38 and JNK kinases. Despite these insights, the physiological ramifications of ribosomal impairment and downstream RSR signaling remain elusive. Here we show that stalling of ribosomes is sufficient to activate ZAKa. In response to amino acid deprivation and full nutrient starvation, RSR impacts on the ensuing metabolic responses in cells, nematodes and mice. The RSR-regulated responses in these model systems include regulation of AMPK and mTOR signaling, survival under starvation conditions, stress hormone production and regulation of blood sugar control. In addition, ZAK-/- mice present with a lean phenotype. Our work highlights stalled ribosomes as metabolic signals and demonstrates a role for RSR signaling in metabolic regulation.
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