TRNA binding and modification by the Escherichia coli dihydrouridine synthase DusA
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ABSTRACT:
PROVIDER: PRJNA1302775 | ENA |
REPOSITORIES: ENA
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Project description:Dihydrouridine (D) is one of the most highly conserved tRNA modifications throughout all domains of life. D20 is particularly conserved and is formed by DusA in E. coli, but its mechanisms and functions remain uncovered. Here, we characterized the molecular mechanisms of DusA in tRNA binding, cofactor oxidation, and tRNA modification, in addition to the cellular functions of DusA in tRNA maturation and mRNA translation. Thereby, we reveal DusA binds tRNA using a two-step mechanism involving local tRNA conformational changes. Although DusA can modify an unmodified tRNA substrate, it binds to previously modified tRNA with a higher affinity. In contrast to the well-studied T arm modifying enzymes TrmA and TruB, DusA does not globally increase tRNA aminoacylation levels, but does improve aminoacylation for specific tRNA species. Despite only few changes in tRNA charging, DusA improves the translation for several specific codons, suggesting a direct role for dihydrouridine in tRNA function on the ribosome. Thus, we propose DusA functions non-redundantly with TrmA and TruB to fine-tune protein synthesis.
2025-09-01 | GSE304803 | GEO
Project description:RNA modifications are fundamental to regulating essential cellular processes, including RNA folding, stability, gene expression, and the accuracy and efficiency of decoding. These modifications are added post-transcriptionally by specialized enzymes, yet their broader roles beyond RNA modification remain poorly understood. In this study, we uncovered a novel function for Vibrio cholerae tRNA dihydrouridine synthase B (VcDusB) in bacterial adaptation to oxidative stress. While VcDusB is traditionally recognized for catalyzing the reduction of uridine to dihydrouridine in tRNA, our findings revealed that its deletion severely compromises V. cholerae survival under hydrogen peroxide-induced oxidative stress. Unexpectedly, VcDusB not only modulated codon decoding efficiency at its target tRNAs, but also influenced global translation, including codons unrelated to its canonical substrates—a phenomenon particularly evident under oxidative stress conditions. Proteomic analysis of the ∆dusB strain exposed a substantial reduction in protein synthesis, highlighting a widespread translational defect in response to stress. Strikingly, point mutations in DusB demonstrated that its protective role during stress was independent of its tRNA modification activity. Instead, its ability to bind tRNA and its NADPH oxidase activity proved vital for survival. These findings reveal a previously unrecognized, non-canonical function of DusB in oxidative stress defense, expanding our understanding of RNA-modifying enzymes. More broadly, this work paves the way for investigating the multifaceted roles of these enzymes in cellular metabolism and stress responses, far beyond their established functions in RNA modification
2025-08-25 | PXD057061 | Pride
Project description:Epitranscriptomic RNA modifications can regulate RNA activity, however there remains a major gap in our understanding of the scope of mRNA chemistry present in biological systems. Here, we develop RNA-mediated activity-based protein profiling (RNABPP), a chemoproteomic strategy relying upon metabolic RNA labeling with the mechanism-based inhibitor 5-fluorocytidine, mRNA interactome capture, and quantitative proteomics, to investigate pyrimidine-modifying enzymes in human cells. In addition to profiling 5-methylcytidine (m5C) methyltransferase activity on mRNA, metabolic deamination of 5-fluorocytidine to 5-fluorouridine allowed us to show that 5-methyluridine (m5U) is present on human mRNA and demonstrate that its formation is primarily mediated by the tRNA-modifying enzyme TRMT2A. Further, our approach uncovered DUS3L, the mammalian homolog of the yeast tRNA-dihydrouridine synthase DUS3, as a novel 5-fluoropyrimidine-reactive protein. We investigate the mechanism of protein-RNA crosslinking, which involves the conserved catalytic Cys residue, and use genetic knockdown combined with quantitative LC-MS/MS analysis to establish that DUS3L installs dihydrouridine (DHU) on human mRNA and small RNA. Finally, we find that DUS3L is important for cell proliferation and protein translation. Taken together, our work provides a general approach for profiling RNA modifying enzyme activity in vivo, and reveals the existence of new pathways for the epitranscriptomic regulation of mRNA behavior in human cells.
2021-07-16 | PXD022645 | Pride
Project description:New Ribosomal RNA Dihydrouridine Synthase in E.coli
| PRJEB77571 | ENA
Project description:Pseudouridine (Ψ), the isomer of uridine, is ubiquitous in most RNA families, including tRNA, rRNA and mRNA. Pseudouridine synthase 3 (PUS3) catalyzes pseudouridylation of position 38/39 in tRNAs, but whether it can modify other RNA types, including mRNA, remains elusive. Here, we determine the single particle cryo-EM structure of apo and tRNA-bound human PUS3, showing how it forms a symmetric homodimer that recognizes the characteristic L-shape of tRNA across two distinct interaction interfaces. Structure-guided and patient-derived mutations validate our structural findings in complementary biochemical assays. Furthermore, we deleted PUS1 and PUS3 in HEK293 cells and used Pseudo-seq to detect Ψ sites in the transcriptome. Although PUS1-dependent sites were detectable in tRNA and mRNA, we did not find any evidence for PUS3 modifying other RNA classes than tRNA. In summary, our work provides the molecular basis for PUS3-mediated tRNA modification in humans and aids in understanding how impairments in its activity lead to intellectual disabilities through defects in tRNA modifications.
2024-07-10 | GSE255287 | GEO
Project description:We used an in vitro pool based strategy to probe the sequence and structural requirements for mRNA target recognition by the yeast tRNA pseudouridine synthase Pus1.
2019-08-14 | GSE99487 | GEO
Project description:We report the identification and quantification of Watson-Crick modifications in tRNA and rRNA through the use of high throughput sequencing. We apply the recently published DM-tRNA-Seq method to generate demethylase treated and untreated 293T samples, and using computational methods we are able to flag sites using a modification index. This index allows us to generate site-resolved information about modification that we can use to identify and quantify Watson-Crick face modifications in tRNA and rRNA. With the demethylase treated samples, we are able to validate numerous nucleotide modifications from demethylase substrates, and the absence of demethylase action also serves to aid in identification. We find numerous novel modification sites in tRNA as well as striking comparisons between tissues cultures lines. Our study reports a comprehensive analysis of the tRNA modification landscape by identifying sites of modification as well as quantifying modification levels.
2017-02-10 | GSE76434 | GEO
Project description:RNA-mediated activity-based protein profiling reveals the substrates of a human dihydrouridine synthase
| PRJNA733999 | ENA
Project description:N7-methylguanosine (m7G) modification is one of the most prevalent tRNA modifications in human. The precise function and molecular mechanism of m7G tRNA modification in regulation of cancer remain poorly understood. Here we showed that m7G tRNA modification, METTL1 and WDR4 are elevated in hepatocellular carcinoma (HCC) tissues and associated with HCC patient prognosis. Functionally, silencing METTL1 or WDR4 inhibits HCC cell proliferation, migration and invasion, while forced expression of wild type METTL1 but not its catalytic dead mutant promotes HCC progression. Knockdown of METTL1 reduces m7G tRNA modification and decreases m7G modified tRNA expression. Mechanistically, METTL1 depletion selectively decreases the mRNA translation of a subset of oncogenic genes, especially cell cycle and EGFR pathway genes, in m7G-related codon dependent manner. Moreover, in vivo studies using Mettl1 knock-in and knockout mice reveal a critical function of Mettl1 mediated m7G tRNA modifications in promoting hepatocarcinogenesis in the hydrodynamics transfection HCC model. Our work uncovers the critical functions of tRNA m7G modification in regulating cancer mRNA translation and promoting hepatocarcinogenesis, thus provides new insights into role of the mis-regulated tRNA modifications in cancers.
2021-06-26 | GSE174492 | GEO
Project description:Dihydrouridine is an abundant and evolutionary conserved modified nucleoside present on tRNA, but characterization and functional studies of individual modification sites and associated DUS writer enzymes in mammals is lacking. Here we use a chemical probing strategy, RNABPP-PS, to identify 5-chlorouridine as a general activity-based probe for human DUS enzymes. We map D modifications using mechanism-based RNA-protein crosslinking and also through chemical reactivity and mutational profiling to reveal the landscape of D modification sites on human tRNAs. Further, we knockout individual DUS genes in two model human cell lines to investigate their regulation of tRNA expression levels and codon-specific translation elongation. We show that whereas D modifications are present across most tRNA species, loss of D only perturbs the translational function of a subset of tRNAs in a cell-type-specific manner. Our work provides powerful chemical strategies for investigating D and DUS enzymes in diverse biological systems and provides insight into the role of a ubiquitous tRNA modification in translational regulation.
2024-10-31 | GSE246816 | GEO