40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling
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ABSTRACT:
PROVIDER: PRJNA608705 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11179726.fastq.gz | Fastqsanger.gz | |||
| SRR11179727.fastq.gz | Fastqsanger.gz | |||
| SRR11179728.fastq.gz | Fastqsanger.gz | |||
| SRR11179729.fastq.gz | Fastqsanger.gz | |||
| SRR11179730.fastq.gz | Fastqsanger.gz |
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Project description:The recycling of ribosomes at stop codons for use in further rounds of translation is critical for efficient protein synthesis. Removal of the 60S subunit is catalyzed by the ATPase Rli1 (ABCE1) while removal of the 40S is thought to require Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR). However, it remains unclear how these Tma proteins cause 40S removal and control reinitiation of downstream translation. Here we developed an enhanced 40S ribosome footprinting strategy to directly observe intermediate steps of ribosome recycling in cells. Deletion of the genes encoding these Tma proteins resulted in broad accumulation of unrecycled 40S subunits at stop codons, directly establishing their role in 40S recycling. Furthermore, the Tma20/Tma22 heterodimer was responsible for a majority of 40S recycling events while Tma64 played a minor role. Introduction of an autism-associated mutation into TMA22 resulted in a loss of 40S recycling activity, linking ribosome recycling and neurological disease.
2021-03-01 | GSE145904 | GEO
Project description:The recycling of ribosomal subunits after translation termination is critical for efficient gene expression. Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR) function as 40S recycling factors in vitro, but it is unknown whether they perform this function in vivo or serve as alternative initiation factors. Ribosome profiling of strains missing these factors revealed 80S ribosomes queued behind the stop codon, consistent with a block in 40S recycling. We found that unrecycled ribosomes could reinitiate translation at AUG codons in the 3’UTR, as evidenced by peaks in the footprint data and 3’UTR reporter analysis. In vitro translation experiments using reporter mRNAs containing upstream ORFs (uORFs) further established that reinitiation increased in the absence of these proteins. In some cases, 40S ribosomes appeared to rejoin with 60S subunits and undergo an alternative 80S reinitiation process in 3’UTRs. These results support a crucial role for Tma64, Tma20, and Tma22 in the recycling of 40S ribosomal subunits at stop codons and translation reinitiation.
2018-08-30 | GSE108942 | GEO
Project description:Although eukaryotic initiation factor 2D (eIF2D) is implicated in translation initiation, re-initiation, and ribosome recycling, its precise role remains unclear. Here, we show that eIF2D promotes 40S ribosome recycling during intrinsic ribosome destabilization (IRD), a process in which ribosomes stochastically destabilize while translating proteins with consecutive acidic amino acids at their NH2-terminus. Unrecycled 40S ribosomes accumulate in eIF2D-deficient cells, leading to 80S ribosome stalling. Selective translation complex profiling (TCP-seq) reveals that eIF2D preferentially associates with IRD-prone regions. The winged-helix (WH) domain, unique to eIF2D but absent in MCTS1–DENR, enhances its binding to 40S subunits, but likely clashes with ABCE1 during stop codon-associated recycling. Loss of eIF2D reduces the expression of IRD-inducing proteins, including splicing factors. Together, these findings define a previously unappreciated role for eIF2D in 40S recycling and clarify its mechanistic divergence from the MCTS1–DENR complex.
2025-10-24 | GSE288755 | GEO
Project description:Hcr1/eIF3j is a sub-stoichiometric subunit of eukaryotic initiation factor 3 (eIF3) that can dissociate the post-termination 40S ribosomal subunit from mRNA in vitro. We examined this ribosome recycling role in vivo by ribosome profiling and reporter assays and found that loss of Hcr1 led to reinitiation of translation in 3’UTRs, consistent with a defect in recycling. However, the defect appeared to be in recycling of the 60S subunit, rather than the 40S subunit, because reinitiation did not require an AUG codon and was suppressed by overexpression of the 60S dissociation factor Rli1/ABCE1. Consistent with a 60S recycling role, overexpression of Hcr1 could not compensate for loss of 40S recycling factors Tma64/eIF2D and Tma20/MCT-1. Intriguingly, loss of Hcr1 triggered higher expression of RLI1 via an apparent feedback loop. These findings suggest Hcr1/eIF3j is recruited to ribosomes at stop codons and may coordinate the transition to a new round of translation.
2019-05-23 | GSE124204 | GEO
Project description:Yeast strains lacking orthologs of mammalian eIF2D (Tma64), and either MCT-1 (Tma20) or DENR (Tma22) are broadly impaired for 40S recycling; however, it was unknown whether this defect leads to reduced 43S PIC levels with an impact on translation of particular mRNAs. To test this, we by combined ribosome footprint profiling with RNA-seq analysis of mRNA abundance.
2021-03-31 | GSE166987 | GEO
Project description:Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR) recycle post-termination 40S subunits in vivo
| PRJNA429210 | ENA
Project description:The recycling of ribosomes at stop codons for use in further rounds of translation is critical for efficient protein synthesis. Removal of the 60S subunit is catalyzed by the ATPase Rli1 (ABCE1) while removal of the 40S is thought to require Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR). However, it remains unclear how these Tma proteins cause 40S removal and control reinitiation of downstream translation. Here we used a 40S ribosome footprinting strategy to directly observe intermediate steps of ribosome recycling in cells. Deletion of the genes encoding these Tma proteins resulted in broad accumulation of unrecycled 40S subunits at stop codons, directly establishing their role in 40S recycling. Furthermore, the Tma20/Tma22 heterodimer was responsible for a majority of 40S recycling events while Tma64 played a minor role. Introduction of an autism-associated mutation into TMA22 resulted in a loss of 40S recycling activity, linking ribosome recycling and neurological disease.
| S-EPMC8137927 | biostudies-literature
Project description:Among the transcript features that regulate translation rate, upstream open reading frames (uORFs) have emerged as a major class of inhibitory elements which limit how many scanning ribosomes reach the start codon of the main protein coding sequence (CDS). Two processes are implicated in ensuring that CDS translation of uORF-containing transcripts can take place nevertheless: first, leaky-scanning, which involves the bypassing of uORF start codons by the scanning 40S ribosome, and second, re-initiation (REI), which allows the 40S subunit of the ribosome that terminated on the uORF stop codon to resume scanning to reach a downstream start codon. REI has remained particularly enigmatic, as it is at odds with generally accepted principles of conventional translation initiation, termination and post-termination subunit recycling. The heterodimer MCTS1-DENR is the first re-initiation-specific factor that has been identified. MCTS1 has been described as the only obligatory partner of DENR. Nevertheless, MCTS1 depletion phenotypes do not always copy the phenotype of DENR depletion in mammalian cells, suggesting that another partner could compensate for the lack of MCTS1. We performed co-immunoprecipitation followed by MS-MS analysis of endogenously FLAG-tagged DENR and identified MCTS2 as a new protein partner. MCTS2 is a homolog and retrogene copy of MCTS1. Downstream analyses demonstrated that MCTS2-DENR was able to promote re-initiation in vitro and showed that Mcts2 mRNA was highly abundant and the protein at least as efficiently synthesized as MCTS1 in NIH3t3 cells, implying that MCTS2 might be the main expressed variant in certain cell types.
2024-11-01 | PXD051482 | Pride
Project description:Among the transcript features that regulate translation rate, upstream open reading frames (uORFs) have emerged as a major class of inhibitory elements which limit how many scanning ribosomes reach the start codon of the main protein coding sequence (CDS). Two processes are implicated in ensuring that CDS translation of uORF-containing transcripts can take place nevertheless: first, leaky-scanning, which involves the bypassing of uORF start codons by the scanning 40S ribosome, and second, re-initiation (REI), which allows the 40S subunit of the ribosome that terminated on the uORF stop codon to resume scanning to reach a downstream start codon. REI has remained particularly enigmatic, as it is at odds with generally accepted principles of conventional translation initiation, termination and post-termination subunit recycling. MCTS1-DENR is the first re-initiation-specific factor that has been identified. Its homolog, EIF2D, is assumed to act in uORF REI as well, yet formal proof of EIF2D-mediated REI has remained scarce. In our study, we present our in vivo analyses of DENR and EIF2D in translation re-initiation in mammalian cells. At the transcriptome-wide scale, ribosome profiling clearly identifies DENR-dependent REI, yet disproves the assumption that EIF2D also functions as a REI-factor.
2024-10-30 | GSE263991 | GEO
Project description:MCT-1 is an oncogene initially identified in a human T-cell lymphoma. Subsequently, MCT-1 protein levels were found to be elevated in a subset of diffuse large B-cell lymphoma. Forced expression of MCT-1 has recently been shown to induce cell proliferation as well as activate survival-related pathways protecting lymphoid cells from apoptosis. We document here that MCT-1 interacts with the density-regulated protein (DENR/DRP), containing the SUI1 translation initiation domain, found in many translation initiation factors. MCT-1 contains the PUA domain, a recently described RNA binding domain that is found in several tRNA and rRNA modification enzymes. Our findings established that MCT-1 protein is interacting with the cap complex through its PUA domain and enhances translation. Furtheremore, our data support a putative role for the MCT-1 oncogene in translation and suggests a mechanism for its role in lymphomagenesis. Keywords: Gene upregulation by MCT-1
2006-09-15 | GSE4805 | GEO