Search results for "TRNA Methyltransferase"
showing 10 items of 16 documents
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,…
Molecular epidemiology of Acinetobacter baumannii in Iran: endemic and epidemic spread of multiresistant isolates
2014
Objectives We examined the molecular epidemiology of Acinetobacter baumannii clinical isolates from two cities (Tehran and Tabriz) of Iran. Methods DiversiLab repetitive extragenic palindromic PCR (rep-PCR), multilocus sequence typing and sequence group multiplex PCR were performed. The presence of resistance mechanisms including metallo-β-lactamases, extended-spectrum β-lactamases, OXA carbapenemases, aminoglycoside-modifying enzymes and RNA methylases was also investigated. Results DiversiLab rep-PCR identified 11 clusters and 11 singleton isolates. Twelve sequence types (STs), including six novel types, were identified. Sequence groups (SGs) 1-3 as well as five additional banding pattern…
Comprehensive DNA methylation analysis of the Aedes aegypti genome
2016
AbstractAedes aegypti mosquitoes are important vectors of viral diseases. Mosquito host factors play key roles in virus control and it has been suggested that dengue virus replication is regulated by Dnmt2-mediated DNA methylation. However, recent studies have shown that Dnmt2 is a tRNA methyltransferase and that Dnmt2-dependent methylomes lack defined DNA methylation patterns, thus necessitating a systematic re-evaluation of the mosquito genome methylation status. We have now searched the Ae. aegypti genome for candidate DNA modification enzymes. This failed to reveal any known (cytosine-5) DNA methyltransferases, but identified homologues for the Dnmt2 tRNA methyltransferase, the Mettl4 (…
<em>In vitro</em> tRNA Methylation Assay with the <em>Entamoeba histolytica</em> DNA and tRNA Methyltransferase Dnmt2 (Ehmeth…
2010
Protozoan parasites are among the most devastating infectious agents of humans responsible for a variety of diseases including amebiasis, which is one of the three most common causes of death from parasitic disease. The agent of amebiasis is the amoeba parasite Entamoeba histolytica that exists under two stages: the infective cyst found in food or water and the invasive trophozoite living in the intestine. The clinical manifestations of amebiasis range from being asymptomatic to colitis, dysentery or liver abscesses. E. histolytica is one of the rare unicellular parasite with 5-methylcytosine (5mC) in its genome. 1, 2 It contains a single DNA methyltransferase, Ehmeth, that belongs to the D…
Translational adaptation to heat stress is mediated by RNA 5‐methylcytosine in Caenorhabditis elegans
2021
Abstract Methylation of carbon‐5 of cytosines (m5C) is a post‐transcriptional nucleotide modification of RNA found in all kingdoms of life. While individual m5C‐methyltransferases have been studied, the impact of the global cytosine‐5 methylome on development, homeostasis and stress remains unknown. Here, using Caenorhabditis elegans, we generated the first organism devoid of m5C in RNA, demonstrating that this modification is non‐essential. Using this genetic tool, we determine the localisation and enzymatic specificity of m5C sites in the RNome in vivo. We find that NSUN‐4 acts as a dual rRNA and tRNA methyltransferase in C. elegans mitochondria. In agreement with leucine and proline bein…
Identification of modifications in microbial, native tRNA that suppress immunostimulatory activity
2012
2′-O-methylation of guanosine 18 is a naturally occurring tRNA modification that can suppress immune TLR7 responses.
RNA cytosine methylation by Dnmt2 and NSun2 promotes tRNA stability and protein synthesis.
2012
The function of cytosine-C5 methylation, a widespread modification of tRNAs, has remained obscure, particularly in mammals. We have now developed a mouse strain defective in cytosine-C5 tRNA methylation, by disrupting both the Dnmt2 and the NSun2 tRNA methyltransferases. Although the lack of either enzyme alone has no detectable effects on mouse viability, double mutants showed a synthetic lethal interaction, with an underdeveloped phenotype and impaired cellular differentiation. tRNA methylation analysis of the double-knockout mice demonstrated complementary target-site specificities for Dnmt2 and NSun2 and a complete loss of cytosine-C5 tRNA methylation. Steady-state levels of unmethylate…
RNA methylation by Dnmt2 protects transfer RNAs against stress-induced cleavage
2010
The covalent modification of nucleic acids plays an important role in regulating the functions of DNA and RNA. DNA modifications have been analyzed in considerable detail, and the characterization of (cytosine-5) DNA methylation has been crucial for understanding the molecular basis of epigenetic gene regulation (Klose and Bird 2006). (Cytosine-5) methylation has also been documented in various RNA species, including tRNA, but the function of RNA methylation has not been firmly established yet (Motorin et al. 2010). Dnmt2 proteins were originally assigned to the DNA methyltransferase family, because of their strong sequence conservation of catalytic DNA methyltransferase motifs (Okano et al…
A New Nuclear Function of the Entamoeba histolytica Glycolytic Enzyme Enolase: The Metabolic Regulation of Cytosine-5 Methyltransferase 2 (Dnmt2) Act…
2009
Cytosine-5 methyltransferases of the Dnmt2 family function as DNA and tRNA methyltransferases. Insight into the role and biological significance of Dnmt2 is greatly hampered by a lack of knowledge about its protein interactions. In this report, we address the subject of protein interaction by identifying enolase through a yeast two-hybrid screen as a Dnmt2-binding protein. Enolase, which is known to catalyze the conversion of 2-phosphoglycerate (2-PG) to phosphoenolpyruvate (PEP), was shown to have both a cytoplasmatic and a nuclear localization in the parasite Entamoeba histolytica. We discovered that enolase acts as a Dnmt2 inhibitor. This unexpected inhibitory activity was antagonized by…
FICC-Seq: a method for enzyme-specified profiling of methyl-5-uridine in cellular RNA.
2019
AbstractMethyl-5-uridine (m5U) is one the most abundant non-canonical bases present in cellular RNA, and in yeast is found at position U54 of tRNAs where modification is catalysed by the methyltransferase Trm2. Although the mammalian enzymes that catalyse m5U formation are yet to be identified via experimental evidence, based on sequence homology to Trm2, two candidates currently exist, TRMT2A and TRMT2B. Here we developed a genome-wide single-nucleotide resolution mapping method, Fluorouracil-Induced-Catalytic-Crosslinking-Sequencing (FICC-Seq), in order to identify the relevant enzymatic targets. We demonstrate that TRMT2A is responsible for the majority of m5U present in human RNA, and t…