Ribosomes act as cryosensors in plants
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ABSTRACT:
PROVIDER: PRJNA701247 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Cold temperatures are a threat to temperate plants, and Arabidopsis thaliana has acquired an adaptive gene expression network controlled by CBF transcription factors. The CBFs are sufficient to enable plants to survive otherwise lethal subzero temperatures. Constitutive CBF expression causes delayed flowering and stunted growth, and plants have evolved the ability to restrict CBF expression to occur only in the cold. This allows plants to anticipate likely freezing events and selectively deploy cold tolerance. The mechanism by which cold stress is sensed is however unknown. Here we show that protein translation rates in plants are proportional to temperature, and reduced translation rates trigger a rise in intracellular free calcium that activates the CAMTA transcription factors, and these directly activate cold-induced gene expression.
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Project description:Translation regulation occurs largely during initiation. Currently, translation initiation can be studied in vitro, but these systems lack features present in vivo and on endogenous mRNAs. Here we develop selective 40S footprinting for visualizing initiating 40S ribosomes on endogenous mRNAs in vivo. It pinpoints where on an mRNA initiation factors join the ribosome to act, and where they leave. We discover that in human cells most scanning ribosomes remain attached to the 5’ cap. Consequently, only one ribosome scans a 5’UTR at a time, and 5’UTR length affects translation efficiency. We discover that eIF3B, eIF4G1 and eIF4E remain on translating 80S ribosomes with a decay half-length of ~12 codons. Hence ribosomes retain these initiation factors while translating short upstream Open Reading Frames (uORFs), providing an explanation for how ribosomes can re-initiate translation after uORFs in humans. This method will be of use for studying translation initiation mechanisms in vivo.
2020-06-25 | GSE139391 | GEO
Project description:A total of 10 cDNA libraries were constructed, representing 3 and 2 independent biological replicates of S. aureus strain KES34 (unmodified ribosomes) and KES30 (m6A2058-modified ribosomes), respectively. Translational efficiency (RPF/mRNA ratios), total mRNA abundance and ribosome density of each ORFs were calculated.
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Project description:PIWI-interacting RNAs (piRNAs) are a class of small non-coding RNAs essential for fertility. In adult mouse testes, most piRNAs are derived from long single-stranded RNAs lacking annotated open reading frames (ORFs). The mechanisms underlying how piRNA sequences are defined during the cleavages of piRNA precursors remain elusive. Here, we show that 80S ribosomes translate the 5′-proximal short ORFs (uORFs) of piRNA precursors. The MOV10L1/Armitage RNA helicase then facilitates the translocation of ribosomes into the uORF downstream regions (UDRs). The ribosome-bound UDRs are targeted by piRNA processing machinery, with the processed ribosome-protected regions becoming piRNAs. The dual modes of interaction between ribosomes and piRNA precursors underlie the distinct piRNA biogenesis requirements at uORFs and UDRs. Ribosomes also mediate piRNA processing in roosters and green lizards, implying that this mechanism is evolutionarily conserved in amniotes. Our results uncover a function for ribosomes on non-coding regions of RNAs and reveal the mechanisms underlying how piRNAs are defined.
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Project description:Translation is initiated by binding of the eIF4F complex to the 5' cap of the mRNA, which is followed by scanning of the initiation codon by scanning ribosomes. Here we demonstrate that the ASC-1 complex (ASCC), which was previously shown to promote the dissociation of colliding 80S ribosomes, associates with the scanning ribosomes to regulate translation initiation. Sel-TCP-seq analysis revealed that ASCC3, a subunit of ASCC with a helicase domain, localizes predominantly to the 5' untranslated region of mRNAs. Knockdown of ASCC3 resulted in reduced translation efficiency associated with reduced 43S preinitiation complex (PIC) loading and a reduced speed of scanning ribosomes. In addition, depletion of the ubiquitin ligase ZNF598, a sensor of collided 80S ribosomes, also reduces the PIC loading and speed of scanning ribosomes. Our results have thus revealed that ASCC is required not only for dissociation of colliding 80S ribosomes, but also for efficient translation initiation by scanning ribosomes.
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Project description:Leaves of angiosperms are made up of multiple distinct cell types. While the function of mesophyll cells, guard cells, phloem companion cells and sieve elements are clearly described, this is not the case for the bundle sheath (BS). To provide insight into the role of the BS in the C3 species Arabidopsis thaliana, we labelled ribosomes in this cell type with a FLAG tag. We then used immunocapture to isolate these ribosomes followed by sequencing of resident mRNAs. This showed that 5% of genes showed specific splice forms in the BS, and that 15% of genes were preferentially expressed in these cells. The BS translatome strongly implicates the BS in specific roles in sulphur transport and metabolism, glucosinolate biosynthesis and trehalose metabolism. Much of the C4 cycle is differentially expressed between the C3 BS and the rest of the leaf. Furthermore, the global patterns of transcript residency on BS ribosomes overlap to a greater extent with cells of the root pericycle than any other cell type. This analysis provides the first insight into the molecular function of this cell type in C3 species, and also indicates that at least some of the characteristics of BS cells in C4 plants are likely ancestral traits unrelated to the C4 photosynthesis.
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Project description:This SuperSeries is composed of the following subset Series: GSE13653: Affinity purification of ribosomes and associated RNAs from stress-treated cells GSE13654: Affinity purification of ribosomes and associated RNAs using tagged Rpl16a and Rpl16b Refer to individual Series
2010-06-25 | E-GEOD-13682 | biostudies-arrayexpress
Project description:We investigated the association of cryptic unstable transcripts (CUTs) to ribosomes in Saccharomyces cerevisiae. We used 5’cap-sequence followed by sucrose gradient fractionation of polyribosome fractions after ultracentrifugation to assess the relative association of transcripts to the ribosomes. We used 5PSeq approach, which measures ribosome dynamics by sequencing the presence of co-translation mRNA degradation intermediates, to assess if cryptic transcripts are engaged in active translation. We performed 5PSeq after glucose depletion to increase the number of ribosomes stop at the 5’UTR and start codon.
2019-10-01 | GSE119134 | GEO
Project description:NAC (nascent polypeptide-associated complex) post-meiotic heterodimeric αβ-complex promoting chaperone-like cotranslational protein folding on the ribosome and its early role in the birth of nascent proteins is suggested. Here, we demonstrate the presence of specific NAC complex (NACtes) associated with ribosomes in spermatocytes. The RNAseq analysis of mRNAs associated with testis-specific and immunoprecipitated NACtes-carrying ribosomes revealed a preferential association of the latter with mRNAs encoding meiotic and post meiotic proteins. The NACtes ribosomes are also shown to be enriched in mRNAs encoding proteins of central metabolism pathways that have been reported as overexpressed in testes. The specificity of association of NACtes ribosomes with particular mRNA sets was also demonstrated by the observation of significant underrepresentation of abundant mRNAs encoding ubiquitously expressed ribosomal proteins in NACtes-associated ribosomes. At the same time, NACtes ribosomes are enriched in mRNA encoding a testis specific ribosomal protein. These results bring new arguments in favor of “specialized ribosomes hypothesis” proposing a special composition of ribosomes necessary for the control of selected gene expression.
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