Nuclear translocation of an aminoacyl-tRNA synthetase may mediate a chronic "integrated stress response"
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ABSTRACT:
PROVIDER: PRJNA649280 | ENA |
REPOSITORIES: ENA
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Project description:Various stress conditions are signaled through phosphorylation of translation initiation factor eukaryotic initiation factor 2α (eIF2α) to inhibit global translation while selectively activating transcription factor ATF4 to aid cell survival and recovery. However, this integrated stress response is acute and cannot resolve lasting stress. Here, we report that tyrosyl-tRNA synthetase (TyrRS), a member of the aminoacyl-tRNA synthetase family that responds to diverse stress conditions through cytosol-nucleus translocation to activate stress-response genes, also inhibits global translation. However, it occurs at a later stage than eIF2α/ATF4 and mammalian target of rapamycin (mTOR) responses. Excluding TyrRS from the nucleus over-activates translation and increases apoptosis in cells under prolonged oxidative stress. Nuclear TyrRS transcriptionally represses translation genes by recruiting TRIM28 and/or NuRD complex. We propose that TyrRS, possibly along with other family members, can sense a variety of stress signals through intrinsic properties of this enzyme and strategically located nuclear localization signal and integrate them by nucleus translocation to effect protective responses against chronic stress.
2023-06-09 | GSE155309 | GEO
Project description:Growth Optimized Aminoacyl-tRNA Synthetase Levels Prevent Maximal tRNA Charging
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Project description:RNA immunoprecipitation and sequencing of aminoacyl-tRNA synthetase-specific genes
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Project description:Charcot-Marie-Tooth disease (CMT) is a length-dependent peripheral neuropathy. The aminoacyl-tRNA synthetases constitute the largest protein family implicated in CMT. Aminoacyl-tRNA synthetases are predominantly cytoplasmic, but are also present in the nucleus. Here we show that a nuclear function of tyrosyl-tRNA synthetase (TyrRS) is implicated in a Drosophila model of CMT. CMT-causing mutations in TyrRS induce unique conformational changes, which confer capacity for aberrant interactions with transcriptional regulators in the nucleus, leading to transcription factor E2F1 hyperactivation. Using neuronal tissues, we reveal a broad transcriptional regulation network associated with wild-type TyrRS expression, which is disturbed when a CMT-mutant is expressed. Pharmacological inhibition of TyrRS nuclear entry with embelin reduces, whereas genetic nuclear exclusion of mutant TyrRS prevents hallmark phenotypes of CMT in the Drosophila model. These data highlight that this translation factor may contribute to transcriptional regulation in neurons, and suggest a therapeutic target for CMT.
2019-10-01 | GSE125311 | GEO
Project description:The Synthetase Sequestration Model (SSM) is a simplified translation model that considers explicitly two main steps in the process of tRNA aminoacylation: first, the tRNA is bound by the aminoacyl tRNA synthetase, and in a second step, the amino acid is attached to the tRNA. The tRNA then participates in the translation reaction, becoming deacylated as a result. The tRNA exists in states bound, charged and uncharged. In the bound state, the tRNA is bound to the synthetase but uncharged, i.e., the tRNA is sequestered by the synthetase. The model predicts how the balance between the three different tRNA states (empty, bound and charged) changes depending on aminoacyl tRNA synthetase availability.
2020-02-05 | MODEL2001080005 | BioModels
Project description:Pseudouridine-mediated translation control of mRNA by methionine aminoacyl tRNA synthetase
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Project description:Summary Aminoacyl-tRNA synthetases (aaRSs) serve a dual role in charging tRNAs. Their enzymatic activities both provide protein synthesis flux and reduce uncharged tRNA levels. Although uncharged tRNAs can negatively impact bacterial growth, substantial concentrations of tRNAs remain deacylated even under nutrient-rich conditions. Here we show that tRNA charging in Bacillus subtilis is not maximized due to optimization of aaRS production during rapid growth, which prioritizes demands in protein synthesis over charging levels. The presence of uncharged tRNAs is alleviated by precisely tuned translation kinetics and the stringent response, both insensitive to aaRS overproduction but sharply responsive to underproduction, allowing for just-enough aaRS production atop a “fitness cliff”. Notably, we find that the stringent response mitigates fitness defects at all aaRS underproduction levels even without external starvation. Thus, adherence to minimal, flux-satisfying protein production drives limited tRNA charging and provides a basis for the sensitivity and setpoints of an integrated growth-control network.
2020-07-20 | GSE141389 | GEO
Project description:Aminoacyl-tRNA synthetases (aaRSs) attach amino acids to their cognate transfer RNAs. In eukaryotes, a subset of cytosolic aaRSs is organized into a multi-synthetase complex (MSC), along with specialized scaffolding proteins referred to as aaRS-interacting multifunctional proteins (AIMPs). In Plasmodium, the causative agent of malaria, the tRNA import protein (tRip), is a membrane protein which participates in tRNA trafficking. Here, we show that tRip is also an AIMP. We identified three aaRSs, namely the glutamyl- (ERS), glutaminyl- (QRS), and methionyl- (MRS) tRNA synthetases, which were specifically co-immunoprecipitated with tRip in Plasmodium berghei blood stage parasites. All four proteins contain an N-terminal GST-like domain involved in MSC assembly. Surprisingly, further dissection of GST-like interactions identified two exclusive heterotrimeric complexes: Q-complex (tRip:ERS:QRS) and M-complex (tRip:ERS:MRS). Gel filtration and light scattering suggest a 2:2:2 stoichiometry for both complexes but with distinct biophysical properties and mutational analysis revealed that the GST-like domains of QRS and MRS use different strategies to bind ERS. Furthermore, the modular organization of the assembled aaRSs and the properties of the specific additional modules supported the proposed localization of these complexes at the parasite membrane.
2022-06-09 | PXD033057 | Pride
Project description:Angiogenesis induced by aminoacyl-tRNA synthetase deficiency is dependent on AAR but not UPR pathways
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Project description:An orthogonal aminoacyl-tRNA synthetase/tRNA pair is a key prerequisite for site-specific incorporation of unnatural amino acids. Due to its high codon suppression efficiency and full orthogonality, the pyrrolysyl-tRNA synthetase/pyrrolysyl-tRNA pair is currently the ideal system for genetic code expansion in both eukaryotes and prokaryotes. There is a pressing need to discover or engineer other fully orthogonal translation systems that allow unnatural amino acids with distinct scaffolds and functionalities to be incorporated into a wide range of living organisms efficiently. Here, through rational chimera design by transplanting the key orthogonal components from the pyrrolysine system, we create multiple chimeric tRNA synthetase/chimeric tRNA pairs, including chimera histidine, phenylalanine, and alanine systems. We further show that these engineered chimeric systems are orthogonal and highly efficient with comparable flexibility to the pyrrolysine system. In addition, the chimera phenylalanine system can incorporate a group of phenylalanine, tyrosine and tryptophan analogues efficiently in both E. coli and mammalian cells. These aromatic amino acids analogous exhibit unique properties and characteristics, including fluorescence, post-translation modification. To our knowledge, most of these molecules have never been shown to be incorporated with fully orthogonal pairs. Therefore, these chimera pairs offer the potential for incorporation of de novo unnatural amino acids into target proteins for a variety of applications.
2020-05-25 | PXD018660 | Pride