TGT damages its substrate tRNAs by the formation of abasic sites in the anticodon loop
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PROVIDER: PRJEB82780 | ENA |
REPOSITORIES: ENA
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Project description:Abasic (AP) sites are one of the most common forms of DNA damage which can lead to polymerase stalling, strand breaks and mutations. We developed snA-seq, a mapping method that reveals the location of abasic sites at base-resolution. Using synthetic DNA, we show that high selectivity for AP DNA is achieved. We use this method to explore the distribution of thymine modifications in the Leishmania major genome, by converting these into abasic sites using a glycosylase enzyme. We also apply snAP-seq to the human genome to study the distribution of endogenous AP sites, in both APE1 knockdown and control cells.
2019-06-12 | E-MTAB-7152 | biostudies-arrayexpress
Project description:The AP-seq provides a genome-wide method for detecting abasic sites among the human and mouse genomes Purpose: Abasic sites are one of the most frequent DNA damage among the genome , which often carries harmful consequences for the genome stability and the normal cell functions. So it is necessary to develop a whole genome abasic sites (AP sites) profiling method to detect all the AP sites among the genome, which we called the AP-seq. Methods: The human and mouse genome are processed with enzymatic fragmentation, damage repair, biotin-dU labeling, and pull-down steps. After the sequencing library preparation, the FASTQ files are produced by the Illumina HiSeq XTen platform. To guarantee the reproducibility, each case of the experiment is present with two biological replicates. Results: The reproducibility of our two biological replicates shows a high correlation which larger than 0.95. And the overlap AP site peaks between the HEK293T and MCF-7 cell line are over 50%, which show a great similarity between the different cell lines. Totally, we identified more than 2000 and 1000 abasic site peaks in human, and mouse cell lines separately. Moreover, the distribution of these AP sites prefer to locate in the intergenic regions and introns.
2020-12-01 | GSE125254 | GEO
Project description:Expression of selenoproteins requires the co-translational incorporation of selenocysteine (Sec) in response to an in-frame UGA codon. The machinery of UGA/Sec re-coding is complex and many factors affect the hierarchy of expression among selenoproteins, including modification of tRNA[Ser]Sec. Its hyper-modification in the anticodon stem loop is influenced by selenium bioavailability, and a mutation in adenosine 37 (A37) that abrogates isopentenylation, has a profound effect on selenoprotein expression in mice. Patients with mutations in tRNA-isopentenyl-transferase (TRIT1) show a severe neurological disorder and hence we wondered whether mutations in TRIT1 negatively affected the expression of selenoproteins. Fibroblasts from a patient carrying a pathogenic R323Q mutation in TRIT1 in homozygosity did not show decreased selenoprotein expression, although recombinant TRIT1R323Q had significantly reduced activity in vitro towards anticodon stem-loop substrates. We thus engineered mice conditionally deficient in Trit1 in hepatocytes and neurons. Selenoprotein expression as assessed by western blotting, 75Se metabolic labeling, and ribosomal profiling was not decreased despite the general reduction of N6-isopentenyl-adenosine in tRNAs. We show that 5-methylcarboxymethylation and 2’O-methylation of U34 occur independently of isopentenylation of A37 in tRNA[Ser]Sec. Reanalyzing previously published ribosomal profiling datasets, we demonstrate that (i) failure of 5-carboxymethylation at U34 is associated with reduced expression of GPX1, but not GPX4, and that (ii) FTSJ1 is not the elusive U34-2’O-methyltransferase involved in the methylation of tRNA[Ser]Sec.
2021-11-17 | GSE183923 | GEO
Project description:During translation, some +1 frameshift mRNA sites are decoded by frameshift suppressor tRNAs that contain an extra base in their anticodon loops. Similarly engineered tRNAs have been used to insert nonnatural amino acids into proteins. Here, we report crystal structures of two anticodon stem-loops (ASLs) from tRNAs known to facilitate +1 frameshifting bound to the 30S ribosomal subunit with their cognate mRNAs. ASL(CCCG) and ASL(ACCC) (5'-3' nomenclature) form unpredicted anticodon-codon interactions where the anticodon base 34 at the wobble position contacts either the fourth codon base or the third and fourth codon bases. In addition, we report the structure of ASL(ACGA) bound to the 30S ribosomal subunit with its cognate mRNA. The tRNA containing this ASL was previously shown to be unable to facilitate +1 frameshifting in competition with normal tRNAs (Hohsaka et al. 2001), and interestingly, it displays a normal anticodon-codon interaction. These structures show that the expanded anticodon loop of +1 frameshift promoting tRNAs are flexible enough to adopt conformations that allow three bases of the anticodon to span four bases of the mRNA. Therefore it appears that normal triplet pairing is not an absolute constraint of the decoding center.
| S-EPMC1869038 | biostudies-literature
Project description:Single-nucleotide resolution mapping of DNA abasic sites by snAP-seq
| PRJEB28471 | ENA
Project description: Not available
| S-EPMC11332805 | biostudies-literature
Project description:The CCA-adding enzyme adds CCA to the 3' ends of transfer RNAs (tRNAs), a critical step in tRNA biogenesis that generates the amino acid attachment site. We found that the CCA-adding enzyme plays a key role in tRNA quality control by selectively marking unstable tRNAs and tRNA-like small RNAs for degradation. Instead of adding CCA to the 3' ends of these transcripts, CCA-adding enzymes from all three kingdoms of life add CCACCA. Here, we report deep sequencing analysis of the 3' ends of tRNA-Ser-CGA and tRNA-Ser-UGA from S. cerevisiae strains and show that hypomodified mature tRNAs are subjected to CCACCA (or poly(A) addition) as part of a rapid tRNA decay pathway in vivo. We conjecture that CCACCA addtion is a universal mechanism for controlling tRNA levels and preventing errors in translation. 121 samples analyzed in total, representing time courses of 10 different yeast strains; Biological replicates for each time point are included
2011-11-17 | E-GEOD-33756 | biostudies-arrayexpress
Project description:DNA damage plays critical role in biology and disease, however, precise understanding of how different types of DNA damage affect cellular functions is far from clear. A major underlying reason for this is paucity of high-resolution methods that can map locations of different types of DNA damage in complex genomes such as those of mammals. Here, we present development and validation of SSiNGLe-AP method that can map a common type of DNA damage, abasic (AP) sites, genome-wide and with high-resolution. We applied this method to six different tissues of mice of different ages and human cancer cell lines. We found non-random distribution of AP sites in mammalian genome that exhibits dynamic enrichment at specific genomic locations, and is significantly influenced by gene expression, age and especially by tissue-type. Overall, these results suggest that we are at the very beginning of understanding the true complexities of genomic patterns of DNA damage.
2022-09-15 | GSE190955 | GEO
Project description:Genome-wide profiling reveals the distribution pattern of abasic sites in mammalian genomes
| PRJNA515700 | ENA
Project description:Understanding the genomic locations of DNA modifications is pivotal for deciphering their roles in gene regulation, mutagenesis, and pathology. The affinity probe-based enrichment of lesion-containing DNA represents a key strategy for sequencing DNA modifications. Existing methods are limited in the specificity of labeling and enrichment of abasic (AP) sites, a prevalent DNA modification and repair intermediate. Herein, we devise a novel approach, termed dual chemical labeling-assisted sequencing (DCL-seq), for mapping AP sites. DCL-seq features two designer compounds for enriching and mapping AP sites specifically at single-nucleotide resolution. For proof of principle, we mapped AP sites in mitochondrial DNA (mtDNA) from cultured human cells under different biological conditions. Also, we demonstrated the broader applicability of the method in sequencing additional DNA modifications in mtDNA, such as N7-methyl-2'-deoxyguanosine and N3-methyl-2'-deoxyadenosine, when coupled with a lesion-specific repair enzyme. Together, DCL-seq holds the promise to sequence multiple DNA modifications in various biological samples.
2022-09-24 | GSE213585 | GEO