Sequencing 5-hydroxymethyluracil via chemical modification and mismatch formation
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PROVIDER: PRJEB24754 | ENA |
REPOSITORIES: ENA
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Project description:This is an oligonucleotide-based proof-of-concept study for a method to detect 5-hydroxymethyluracil (5hmU) in a single base-resolution on NGS platform. The method will be useful to identify the effect of 5hmU to genome functions.
2018-06-08 | E-MTAB-6456 | biostudies-arrayexpress
Project description:5-hydroxymethyluracil (5hmU) is a thymine base modification found in genomes of a diverse range of organisms. To explore the functional importance of 5hmU, we developed a method for the genome-wide mapping of 5hmU-modified loci based on a chemical tagging strategy for the hydroxymethyl group. We applied the method to generate genome-wide maps of 5hmU in parasitic protozoan Leishmania, where 5hmU forms enzymatically via hydroxylation of thymine. In the genus, another thymine modification 5-(β-glucopyranosyl) hydroxymethyluracil (base J) plays key roles during transcription. To elucidate relationships between 5hmU and base J, we also mapped base J loci by introducing a chemical tagging strategy for the glucopyranoside residue. Results: Observed 5hmU peaks were highly consistent among technical replicates, confirming the robustness of the method. 5hmU were particularly enriched in strand switch regions, telomeric regions and intergenic regions. Over 90% of 5hmU-enriched loci overlapped with base J-enriched loci, which occurred mostly within strand switch regions. We also identified loci comprising 5hmU but not base J. These 5hmU-specific loci were enriched with motifs consisting of a stretch of thymine bases and associated with higher RNA levels. Conclusions: By chemically detecting 5hmU we provide the first genome-wide map of 5hmU, which will help addressing the emerging interest in the role of 5hmU. The presence of 5hmU-specific loci may suggest that 5hmU has unique roles.
2016-12-15 | GSE83384 | GEO
Project description:Transfected siRNAs regulate numerous transcripts sharing limited complementarity to the RNA duplex. This unintended (“off-target”) silencing can hinder the use of RNAi to define gene function. Here we describe position-specific, sequence-independent chemical modifications that reduced silencing of partially-complementary transcripts by all siRNAs tested. Silencing of perfectly-matched targets was unaffected by these modifications. The chemical modification also reduced off-target phenotypes in growth inhibition studies. Key to the modification was 2’-O-methyl ribosyl substitution at position 2 in the guide strand, which reduced silencing of most off-target transcripts with complementarity to the seed region of the siRNA guide strand. The sharp position-dependence of 2’-O-methyl ribosyl modification contrasts with the broader position dependence of base pair substitutions within the seed region, suggesting a role for position 2 of the guide strand distinct from its effects on pairing to target transcripts. Keywords: Microarray analysis, chemical modification walk, dose response
2006-09-07 | GSE5769 | GEO
Project description:In dinoflagellates, the most unique and divergent nuclear organization among the known diversity of eukaryotes has evolved. The list of highly unusual features of dinoflagellate nuclei and genomes is long -- permanently condensed liquid crystalline chromosomes, in which histones are not the main packaging component, genes organized as very long unidirectional gene arrays, general absence of transcriptional regulation, high abundance of the otherwise very rare DNA modification 5-hydroxymethyluracil (5-hmU), and many others. Most of these fascinating properties were originally identified in the 1970s and 1980s but have received very little attention in recent decades using modern genomic tools. In this work, we address some of the outstanding questions regarding dinoflagellate genome organization by mapping the genome-wide distribution of 5-hmU (using both immunoprecipitation-based and basepair-resolution chemical mapping approaches) and of chromatin accessibility in the genome of the dinoflagellate Breviolum minutum. We find that the 5-hmU modification is preferentially enriched over certain classes of repetitive elements, and also often coincides with the boundaries between gene arrays. It is generally anti-correlated with chromatin accessibility, the levels of which are lower in those regions. We discuss the potential roles of 5-hmU in the functional organization of dinoflagellate genomes and its relationship to the transcriptional landscape of gene arrays.
2023-10-19 | GSE241969 | GEO
Project description:5-Hydroxymethyluracil (5hmU) is a thymine modification existing in the genomes of a number of living organisms. The post-replicative formation of 5hmU occurs via hydroxylation of thymine, which can be mediated by the ten-eleven translocation (TET) dioxygenases in mammalian and J-binding proteins (JBPs) in protozoan genomes, respectively. In addition, 5hmU also can be generated through oxidation of thymine by reactive oxygen species or from deamination of 5hmC by activation-induced cytidine deaminase (AID) or APOBEC family enzymes. While the biological roles of 5hmU have not been fully explored, identifying its genomic location will assist in elucidating its functions. Herein, we report a method of enzyme-mediated bioorthogonal labeling to selectively enrich genomic regions containing 5hmU. 5hmU DNA kinase (5hmUDK) was utilized to selectively install an azide group or alkynyl group into the hydroxyl group of 5hmU followed by incorporation of the biotin linker through click chemistry and capture of 5hmU-containing DNA fragments via streptavidin pull-down. The enriched fragments were applied to deep sequencing to map the location of 5hmU. With this established enzyme-mediated bioorthogonal labeling strategy, we achieved the genome-wide mapping of 5hmU in Trypanosoma brucei (T. brucei) genomes. The method described here will allow for a better understanding of the functional roles and dynamics of 5hmU in genomes
2021-07-11 | GSE179809 | GEO
Project description:Tiled regions surrounding 5 human genes as 36mers, HBG2, TIMP3, SYN3, FLNA, FBX07. The first three of these genes, we tiled with various mismatch oligos in addition to 'perfect match' oligos. Keywords: Mismatch hybridization experiment Tiled perfect match and various designs of mismatch oligonucleotide for several human genes. Goal was to observe the influence of various MM types on hybridization behavior in human, and compare it to yeast (see related slide).
2010-05-05 | E-GEOD-13172 | biostudies-arrayexpress
Project description:Tiled regions surrounding 5 human genes as 36mers, HBG2, TIMP3, SYN3, FLNA, FBX07. The first three of these genes, we tiled with various mismatch oligos in addition to 'perfect match' oligos. Keywords: Mismatch hybridization experiment
2009-02-18 | GSE13172 | GEO
Project description:Chemical probing has the power to provide insight into RNA conformation in vivo and in vitro, but interpreting the results depends on methods to detect the chemically modified nucleotides. Traditionally, the presence of modified bases was inferred from their ability to halt reverse transcriptase during primer extension and the locations of termination sites observed by electrophoresis or sequencing. More recently, modification-induced mutations have been used as a readout for chemical probing data. Given variable propensity for mismatch incorporation and read-through with different reverse transcriptases, we examined how termination and mutation events compare to each other in the same chemical probing experiments. We found that mutations and terminations induced by dimethyl sulfate probing are both specific for methylated bases, but these two measures have surprisingly little correlation and represent largely non-overlapping indicators of chemical modification data. We also show that specific biases for modified bases depend partly on local sequence context, and that different reverse transcriptases show different biases toward reading a modification as a stop or a mutation. These results support approaches that incorporate analysis of both termination and mutation events into RNA probing experiments.
2017-09-26 | GSE97609 | GEO
Project description:Tiled 10kb region centered around ACT1 gene (YFL039C, CHROMOSOME 6 @ coords 48760-59195), double-stranded, 36mers at 1bp spacing, with mismatches and deletions; also tiled 6 genes of interest (YBL092W, YGR155W, YOL040C, YOR312C, YMR242C, YLR229C), coding strand only, 36mers at 1bp spacing, with some mismatches and deletions Keywords: Mismatch hybridization experiment Tiled perfect match and various designs of mismatch oligonucleotide for several yeast genes. Goal was to observe the influence of various MM types on hybridization behavior in yeast and compare it to human (see related slide).
2010-05-05 | E-GEOD-13174 | biostudies-arrayexpress
Project description:Raw data used for the article "Chemical Modification of a Bacterial Siderophore by a Competitor in Dual-Species Biofilms"
2023-05-12 | MSV000091922 | GNPS