Search results for "trna"

Next‐Generation Sequencing‐Based RiboMethSeq Protocol for Analysis of tRNA 2′‐O‐Methylation

2017

Analysis of RNA modifications by traditional physico‐chemical approaches is labor  intensive,  requires  substantial  amounts  of  input  material  and  only  allows  site‐by‐site  measurements.  The  recent  development  of  qualitative  and  quantitative  approaches  based  on   next‐generation sequencing (NGS) opens new perspectives for the analysis of various cellular RNA  species.  The  Illumina  sequencing‐based  RiboMethSeq  protocol  was  initially  developed  and  successfully applied for mapping of ribosomal RNA (rRNA) 2′‐O‐methylations. This method also  gives excellent results in the quantitative analysis of rRNA modifications in different species and  under varying growth condi…

Biallelic variants in LARS2 and KARS cause deafness and (ovario)leukodystrophy

2019

Supplemental Digital Content is available in the text.

The RNA methyltransferase Dnmt2 methylates DNA in the structural context of a tRNA

2016

The amino acid sequence of Dnmt2 is very similar to the catalytic domains of bacterial and eukaryotic DNA-(cytosine 5)-methyltransferases, but it efficiently catalyzes tRNA methylation, while its DNA methyltransferase activity is the subject of controversial reports with rates varying between zero and very weak. By using composite nucleic acid molecules as substrates, we surprisingly found that DNA fragments, when presented as covalent DNA-RNA hybrids in the structural context of a tRNA, can be more efficiently methylated than the corresponding natural tRNA substrate. Furthermore, by stepwise development of tRNAAsp, we showed that this natural Dnmt2 substrate could be engineered to employ R…

Mechanism and biological role of Dnmt2 in Nucleic Acid Methylation

2016

ABSTRACT A group of homologous nucleic acid modification enzymes called Dnmt2, Trdmt1, Pmt1, DnmA, and Ehmet in different model organisms catalyze the transfer of a methyl group from the cofactor S-adenosyl-methionine (SAM) to the carbon-5 of cytosine residues. Originally considered as DNA MTases, these enzymes were shown to be tRNA methyltransferases about a decade ago. Between the presumed involvement in DNA modification-related epigenetics, and the recent foray into the RNA modification field, significant progress has characterized Dnmt2-related research. Here, we review this progress in its diverse facets including molecular evolution, structural biology, biochemistry, chemical biology,…

2016

Urm1 is a unique dual-function member of the ubiquitin protein family and conserved from yeast to man. It acts both as a protein modifier in ubiquitin-like urmylation and as a sulfur donor for tRNA thiolation, which in concert with the Elongator pathway forms 5-methoxy-carbonyl-methyl-2-thio (mcm5s2) modified wobble uridines (U34) in anticodons. Using Saccharomyces cerevisiae as a model to study a relationship between these two functions, we examined whether cultivation temperature and sulfur supply previously implicated in the tRNA thiolation branch of the URM1 pathway also contribute to proper urmylation. Monitoring Urm1 conjugation, we found urmylation of the peroxiredoxin Ahp1 is suppre…

Differentially Expressed tRNA-Derived Small RNAs Co-Sediment Primarily with Non-Polysomal Fractions in Drosophila

2017

Recent studies point to the existence of poorly characterized small regulatory RNAs generated from mRNAs, rRNAs and tRNAs. To explore the subcellular location of tRNA-derived small RNAs, 0–1 and 7–8 h Drosophila embryos were fractionated on sucrose density gradients. Analysis of 12,553,921 deep-sequencing reads from unfractionated and fractionated Drosophila embryos has revealed that tRFs, which are detected mainly from the 5’ends of tRNAs, co-sediment with the non-polysomal fractions. Interestingly, the expression levels of a subset of tRFs change temporally following thematernal-to-zygotic transition in embryos. We detected non-polysomal association of tRFs in S2 cells as well. Differenti…

Non-Redundant tRNA Reference Sequences for Deep Sequencing Analysis of tRNA Abundance and Epitranscriptomic RNA Modifications

2021

Analysis of RNA by deep-sequencing approaches has found widespread application in modern biology. In addition to measurements of RNA abundance under various physiological conditions, such techniques are now widely used for mapping and quantification of RNA modifications. Transfer RNA (tRNA) molecules are among the frequent targets of such investigation, since they contain multiple modified residues. However, the major challenge in tRNA examination is related to a large number of duplicated and point-mutated genes encoding those RNA molecules. Moreover, the existence of multiple isoacceptors/isodecoders complicates both the analysis and read mapping. Existing databases for tRNA sequencing pr…

Balancing of mitochondrial translation through METTL8-mediated m3C modification of mitochondrial tRNAs.

2021

Mitochondria contain a specific translation machinery for the synthesis of mitochondria-encoded respiratory chain components. Mitochondrial tRNAs (mt-tRNAs) are also generated from the mitochondrial DNA and, similar to their cytoplasmic counterparts, are post-transcriptionally modified. Here, we find that the RNA methyltransferase METTL8 is a mitochondrial protein that facilitates 3-methyl-cytidine (m3C) methylation at position C32 of the mt-tRNASer(UCN) and mt-tRNAThr. METTL8 knockout cells show a reduction in respiratory chain activity, whereas overexpression increases activity. In pancreatic cancer, METTL8 levels are high, which correlates with lower patient survival and an enhanced resp…

2'-O-methylation within prokaryotic and eukaryotic tRNA inhibits innate immune activation by endosomal Toll-like receptors but does not affect recogn…

2019

Bacterial RNA has emerged as an important activator of innate immune responses by stimulating Toll-like receptors TLR7 and TLR8 in humans. Guanosine 2′-O-methylation at position 18 (Gm18) in bacterial tRNA was shown to antagonize tRNA-induced TLR7/8 activation, suggesting a potential role of Gm18 as an immune escape mechanism. This modification also occurs in eukaryotic tRNA, yet a physiological immune function remained to be tested. We therefore set out to investigate the immune modulatory role of Gm18 in both prokaryotic and eukaryotic microorganisms, Escherichia coli and Saccharomyces cerevisiae, and in human cells. Using RiboMethSeq analysis we show that mutation of trmH in E. coli, trm…

Naturaleza dinámica de MnmG. Una flavoenzima ancestral modificadora de tRNAs bacterianos y mitocondriales

2016

La modificación del tRNA es un proceso universal presente en todos los organismos y orgánulos de origen endosimbionte como mitocondria y cloroplasto. Las modificaciones de la uridina localizada en la posición de tambaleo del anticodón (conocida abreviadamente como U34) que implican la adición de un grupo aminometileno (o derivado) en la posición 5 (xm5) son especialmente importantes en el proceso de reconocimiento codón-anticodón y, por tanto, para una descodificación óptima del mensaje genético. La ausencia de estas modificaciones se asocia con un fenotipo pleiotrópico e incluso letalidad en determinadas condiciones. Las modificaciones del tipo xm5 son introducidas en la U34 de los tRNAs d…