Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Structural inventory of native ribosomal ABCE1-43S pre-initiation complex

ABSTRACT: In eukaryotic translation, the termination and recycling phases are linked to subsequent initiation by persistence of several factors. These comprise the large eIF3 complex, eIF3j (Hcr1 in yeast) and the ATP-binding cassette protein ABCE1 (Rli1 in yeast). The ATPase is mainly active as a recycling factor, but it can remain bound to the dissociated 40S subunit until formation of 43S pre-initiation complexes. However, its functional role and native architectural context remains largely enigmatic. Here, we present an architectural inventory of native yeast and human ABCE1-containing pre-initiation complexes by cryo-EM. We found that ABCE1 was mostly associated with early 43S but also later 48S phases of initiation. It adopted a novel hybrid conformation of its nucleotide binding sites, which was stabilized by the N-terminus of eIF3j. Further, eIF3j occupied the mRNA entry channel via its ultimate C-terminus explaining its antagonistic role with respect to mRNA binding. Moreover, the native human samples provided a near-complete molecular picture of the architecture and sophisticated interaction network of the 43S-bound eIF3 complex and also the eIF2 ternary complex containing the initiator tRNA.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Saccharomyces Cerevisiae (baker's Yeast)

SUBMITTER: Mia Potocnjak

LAB HEAD: Roland Beckmann

PROVIDER: PXD020849 | Pride | 2020-10-16

REPOSITORIES: Pride

ACCESS DATA

Json Xml

Similar Datasets

Cellular translational enhancer elements that recruit eukaryotic initiation factor 3

Project description:Translation initiation is a highly regulated process which broadly affects eukaryotic gene expression. Eukaryotic initiation factor 3 (eIF3) is a central player in canonical and alternative pathways for ribosome recruitment. Here we have investigated how direct binding of eIF3 contributes to the large and regulated differences in protein output conferred by different 5′-untranslated regions (5′-UTRs) of cellular mRNAs. Using an unbiased high-throughput approach to determine the affinity of budding yeast eIF3 for native 5′-UTRs from 4,252 genes, we demonstrate that eIF3 binds specifically to a subset of 5′-UTRs that contain a short unstructured binding motif, AMAYAA. eIF3 binding mRNAs have higher ribosome density in growing cells and are preferentially translated under certain stress conditions, supporting the functional relevance of this interaction. Our results reveal a new class of translational enhancer and suggest a mechanism by which changes in core initiation factor activity enact mRNA-specific translation programs.

2022-07-06 | GSE180046 | GEO

eIF3 PAR-CLIP in 293T cells

Project description:Regulation of protein synthesis is fundamental for all aspects of eukaryotic biology by controlling development, homeostasis, and stress responses. The 13-subunit, 800-kDa eukaryotic initiation factor 3 (eIF3) organizes initiation factor and ribosome interactions required for productive translation. However, current understanding of eIF3 function does not explain genetic evidence correlating eIF3 deregulation with tissue-specific cancers and developmental defects. Here we report the genome-wide discovery of human transcripts that interact with eIF3 using photo-activatable crosslinking and immunoprecipitation (PAR-CLIP). eIF3 binds to a highly specific programme of messenger RNAs (mRNAs) involved in cell growth control processes, including cell cycling, differentiation, and apoptosis, via the mRNA 5' untranslated region (5' UTR). Surprisingly, functional analysis of the interaction between eIF3 and two mRNAs encoding cell proliferation regulators, c-Jun and BTG1, reveals that eIF3 employs different modes of RNA stem loop binding to exert either translational activation or repression. Our findings illuminate a new role for eIF3 in governing a specialized repertoire of gene expression and suggest that binding of eIF3 to specific mRNAs could be targeted to control carcinogenesis. 293T cells were treated with 4-thiouridine and protein-RNA complexes were crosslinked, and eIF3-RNA complexes were immunoprecipitated.

2015-04-06 | E-GEOD-65004 | biostudies-arrayexpress

eIF3 and its mRNA-entry-channel arm contribute to the recruitment of mRNAs with long 5'-untranslated regions

Project description:Translation initiation in eukaryotes is multi-step pathway and the most regulated phase of translation. Eukaryotic initiation factor 3 is the largest and most complex of the translation initiation factors, and it contributes to events throughout the initiation pathway. In particular, eIF3 appears to play critical roles in mRNA recruitment. More recently, eIF3 has been implicated in driving the selective translation of specific classes of mRNAs. However, unraveling the mechanism of these diverse contributions — and disentangling the roles of the individual subunits of the eIF3 complex — remains challenging. We employed ribosome profiling of budding yeast cells expressing two distinct mutations targeting the eIF3 complex. These mutations either disrupt the entire complex or subunits positioned near the mRNA-entry channel of the ribosome which appear to relocate during or in response to mRNA binding and start-codon recognition. Disruption of either the entire eIF3 complex or specific targeting of these subunits affects mRNAs with long 5’-untranslated regions and whose translation is more dependent on eIF4A, eIF4B, and Ded1 but less dependent on eIF4G, eIF4E, and PABP. Disruption of the entire eIF3 complex further affects mRNAs involved in mitochondrial processes and with structured 5’-untranslated regions. Comparison of the suite of mRNAs most sensitive to both mutations with those uniquely sensitive to disruption of the entire complex sheds new light on the specific roles of individual subunits of the eIF3 complex.

2022-01-11 | GSE190601 | GEO

Unique features of mRNA translation initiation in trypanosomatids

Project description:The 43S pre-initiation complex (PIC) assembly requires establishment of numerous interactions among eukaryotic initiation factors (eIFs), Met-tRNAiMet and the small ribosomal subunit (40S). Owing to several differences in the structure and composition of kinetoplastidian 40S compared to their mammalian counterparts, translation initiation in trypanosomatids is suspected to display substantial variability. Here, we determined the structure of the 43S PIC from Trypanosoma cruzi, the Chagas disease parasite, showing numerous specific features, such as different eIF3 structure and interactions with the large rRNA expansion segments 9S, 7S and 6S, and the association of a kinetoplastid-specific ~245 kDa DDX60-like helicase. We also revealed a previously undetermined binding site of the eIF5 C-terminal domain, and terminal tails of eIF2β, eIF1, eIF1A and eIF3 c and d subunits, uncovering molecular details of their critical activities.

2020-03-25 | PXD016063 | Pride

m6A in 5â untranslated regions promotes cap-independent translation of mRNA

Project description:N6-methyladenosine (m6A) is a widespread internal RNA modification whose function is poorly understood. Here we report that m6A residues within the 5'UTR promote a novel form of cap-independent translation which is mediated through an interaction between m6A residues and the translation initiation factor, eIF3. We present eIF3a PAR-iCLIP data which demonstrate that eIF3 predominantly binds mRNAs within the 5'UTR. eIF3 binding sites are also in proximity to m6A residues within the 5'UTR of cellular mRNAs. Two replicates of eIF3a PAR-iCLIP in HEK293T cells.

2015-10-26 | E-GEOD-73405 | biostudies-arrayexpress

eIF3 PAR-CLIP in 293T cells

2015-04-06 | GSE65004 | GEO

Dynamic O-GlcNAcylation of eIF3a controls translation reinitiation during integrated stress response

Project description:In eukaryotic cells, many mRNAs possess upstream open reading frames (uORFs) in addition to the main coding region. After uORF translation, the ribosome could either recycle at the stop codon or resume scanning for downstream start codons in a process known as reinitiation. Accumulating evidence suggests that some initiation factors, including eIF3, linger on the early elongating ribosome, forming an eIF3-80S complex. Very little is known how the eIF3 is carried along with the 80S during elongation and its implications in subsequent translation reinitiation. Here we report that eIF3a undergoes dynamic O-GlcNAc modification in response to nutrient starvation. Stress-induced de-O-GlcNAcylation promotes eIF3 retention on the elongating ribosome and facilitates reinitiation at downstream start codons. Eliminating the modification site from eIF3a via genome editing induces ATF4 reinitiation under the nutrient rich condition. Our findings illustrate a mechanism in balancing ribosome recycling and reinitiation, thereby linking integrated stress response and translational reprogramming.

2021-11-01 | GSE181040 | GEO

Hcr1/eIF3j is a 60S ribosomal subunit recycling accessory factor in vivo

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

Cancer associated mRNAs regulated by the Helix Loop Helix motif of human EIF3A

Project description:Improper regulation of translation initiation, a vital check-point of protein synthesis in the cell, has been linked to a number of cancers. Overexpression of protein subunits of eukaryotic translation initiation factor 3 (eIF3) has been associated with increased translation of mRNAs involved in cell proliferation. In addition to playing a major role in general translation initiation by serving as a scaffold for the assembly of translation initiation complexes, eIF3 regulates translation of specific cellular mRNAs and viral RNAs. Mutations in the N-terminal Helix-Loop-Helix (HLH) RNA-binding motif of the EIF3A subunit in eIF3 interfere with Hepatitis C Virus Internal Ribosome Entry Site (IRES) mediated translation initiation in vitro. Here we use RNA-seq and ribosome profiling of engineered lentiviral HEK293T cells to show that the EIF3A HLH motif controls translation of a small set of cellular transcripts enriched in oncogenic mRNAs, including MYC.

2018-08-08 | GSE118239 | GEO

seCLIP of C. elegans EIF-3.G in the cholinergic motor neurons

Project description:Protein translation is tightly regulated at the initiation phase, which entails exceedingly complex interactions among multiple EIF initiation factors to bring the ribosome to the mRNA and scan the 5’ leader sequence for the start codon. EIF-3 contains multiple subunits with essential and emerging regulatory activities throughout the translation initiation pathway. However, it remains poorly understood how individual components of the EIF3 complex contribute to the selective regulation of translation in multicellular organisms. Here, through studies of a missense mutation in C. elegans EIF-3.G, an RNA-binding subunit of EIF3, we have dissected mechanisms of how regulation of protein translation initiation modulates neuronal excitation. EIF-3.G(C130Y) alters a conserved Zinc Finger and behaves as a gain-of-function. We show that while EIF-3.G(C130Y) permits essential aspects of translation initiation, this variant functionally involves its RNA binding activity in regulating protein synthesis. We mapped EIF-3.G binding sites in the C. elegans cholinergic motor neuron transcriptome and identified a significant representation of mRNAs containing long and GC-rich 5' UTRs and in mRNAs exhibiting activity-dependent transcript level changes. Our results suggest that modulation of the scanning process of translation initiation by EIF3 contributes homeostatic regulation to synaptic activity changes.

2021-08-18 | GSE152704 | GEO

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data