DNA Motif Recombination
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PROVIDER: PRJEB29483 | ENA |
REPOSITORIES: ENA
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Project description:Crossovers formed by recombination between homologous chromosomes are important for proper homolog segregation during meiosis and for generation of genetic diversity. Optimal molecular analysis of DNA intermediates of recombination requires synchronous cultures. We previously described a mutant, pat1-as2, of the fission yeast Schizosaccharomyces pombe that undergoes synchronous meiosis at 25°C when an ATP analog is added to the culture. Here, we compare recombination intermediates in pat1-as2 at 25°C with those in the widely used pat1-114 temperature-sensitive mutant at 34°C, a temperature higher than optimal. DNA double-strand breaks at most hotspots are similarly abundant in the two conditions but, remarkably, a few hotspots are distinctly deficient at 25°C. In both conditions Holliday junctions at DNA break hotspots form more frequently between sister chromatids than between homologs, but a novel species, perhaps arising from invasion by only one end of broken DNA, is more readily observed at 25°C. Our results confirm the validity of previous assays of recombination intermediates in S. pombe and provide new information on the mechanism of meiotic recombination.
2013-09-20 | GSE49961 | GEO
Project description:Crossovers formed by recombination between homologous chromosomes are important for proper homolog segregation during meiosis and for generation of genetic diversity. Optimal molecular analysis of DNA intermediates of recombination requires synchronous cultures. We previously described a mutant, pat1-as2, of the fission yeast Schizosaccharomyces pombe that undergoes synchronous meiosis at 25°C when an ATP analog is added to the culture. Here, we compare recombination intermediates in pat1-as2 at 25°C with those in the widely used pat1-114 temperature-sensitive mutant at 34°C, a temperature higher than optimal. DNA double-strand breaks at most hotspots are similarly abundant in the two conditions but, remarkably, a few hotspots are distinctly deficient at 25°C. In both conditions Holliday junctions at DNA break hotspots form more frequently between sister chromatids than between homologs, but a novel species, perhaps arising from invasion by only one end of broken DNA, is more readily observed at 25°C. Our results confirm the validity of previous assays of recombination intermediates in S. pombe and provide new information on the mechanism of meiotic recombination. DNA double-strand break analysis by immunoprecipation of Rec12-FLAG covalently linked to DNA (without exogenous crosslinking agent used) following meiotic induction via pat1-114 or pat1-as2 alleles
2013-09-20 | E-GEOD-49961 | biostudies-arrayexpress
Project description:The information about when and where each gene is to be expressed is mainly encoded in the DNA sequence of enhancers, sequence elements that comprise binding sites (motifs) for different transcription factors (TFs). Most of the research on enhancer sequences has been focused on TF motif presence, while the enhancer syntax, i.e. the flexibility of important motif positions and how the sequence context modulates the activity of TF motifs, remain poorly understood. Here, we explore the rules of enhancer syntax by a two-pronged approach in Drosophila melanogaster S2 cells: we (1) replace important motifs by an exhaustive set of all possible 65,536 eight-nucleotide-long random sequences and (2) paste eight important TF motif types into 763 motif positions within 496 enhancers. These complementary strategies reveal that enhancers display constrained sequence flexibility and the context-specific modulation of motif function. Important motifs can be functionally replaced by hundreds of sequences constituting several distinct motif types, but only a fraction of all possible sequences and motif types restore enhancer activity. Moreover, TF motifs contribute with different intrinsic strengths that are strongly modulated by the enhancer sequence context (the flanking sequence, presence and diversity of other motif types, and distance between motifs), such that not all motif types can work in all positions. Constrained sequence flexibility and the context-specific modulation of motif function are also hallmarks of human enhancers and TF motifs, as we demonstrate experimentally. Overall, these two general principles of enhancer sequences are important to understand and predict enhancer function during development, evolution and in disease.
2022-12-15 | GSE211657 | GEO
Project description:The information about when and where each gene is to be expressed is mainly encoded in the DNA sequence of enhancers, sequence elements that comprise binding sites (motifs) for different transcription factors (TFs). Most of the research on enhancer sequences has been focused on TF motif presence, while the enhancer syntax, i.e. the flexibility of important motif positions and how the sequence context modulates the activity of TF motifs, remain poorly understood. Here, we explore the rules of enhancer syntax by a two-pronged approach in Drosophila melanogaster S2 cells: we (1) replace important motifs by an exhaustive set of all possible 65,536 eight-nucleotide-long random sequences and (2) paste eight important TF motif types into 763 motif positions within 496 enhancers. These complementary strategies reveal that enhancers display constrained sequence flexibility and the context-specific modulation of motif function. Important motifs can be functionally replaced by hundreds of sequences constituting several distinct motif types, but only a fraction of all possible sequences and motif types restore enhancer activity. Moreover, TF motifs contribute with different intrinsic strengths that are strongly modulated by the enhancer sequence context (the flanking sequence, presence and diversity of other motif types, and distance between motifs), such that not all motif types can work in all positions. Constrained sequence flexibility and the context-specific modulation of motif function are also hallmarks of human enhancers and TF motifs, as we demonstrate experimentally. Overall, these two general principles of enhancer sequences are important to understand and predict enhancer function during development, evolution and in disease.
2022-12-15 | GSE211654 | GEO
Project description:The Saccharomyces cerevisae RAD3 gene is homolog of human XPD, an essential gene encoding a DNA helicase of the TFIIH complex involved in both nucleotide excision repair (NER) and transcription. Mutant alleles of RAD3 have been identified (rad3-101 and rad3-102) that have partial defects in DNA repair associated with a strong hyper-recombination (hyper-Rec) phenotype. Previous studies showed that the hyper-Rec phenotype associated with rad3-101 and rad3-102 can be explained as a consequence of persistent single-stranded DNA gaps that are converted to recombinogenic double-strand breaks (DSBs) by replication. We have further characterized these events using a system in which the reciprocal products of mitotic recombination between homologs are recovered as red and white sectored colonies. Both rad3-101 and rad3-102 elevate the frequency of sectored colonies about 100-fold. Subsequent mapping of these events shows that three-quarters of crossovers between homologs induced in hyper-Rec rad3 mutants reflect DSBs formed in at the same positions in both sister chromatids (double sister-chromatid breaks, DSCBs). The remainder reflects DSBs formed in single chromatids (single chromatid breaks, SCBs). The ratio of DSCBs to SCBs is similar to that observed for spontaneous recombination events in wild-type cells. In addition to examining crossovers on chromosome V, we mapped 216 unselected genomic alterations throughout the genome including crossovers, gene conversions, deletions, and duplications. We found a significant association between the location of these recombination events and regions with elevated gamma-H2AX. In addition, there was a hotspot for deletions and duplications at the IMA2 and HXT11 genes near the left end of chromosome XV. A comparison of these data with our previous analysis of spontaneous mitotic recombination events suggests that a sub-set of spontaneous events in wild-type cells may be initiated by incomplete NER reactions, and that DSCBs, which cannot be repaired by sister-chromatid recombination, are a major source of mitotic recombination between homologous chromosomes.
2015-12-30 | GSE76395 | GEO
Project description:We used a high-density tiling array to estimate genetic recombination rate among 32 independent recombinant progeny of a P. falciparum genetic cross (7G8 M-CM-^W GB4). We detected 3184 segregating multi-probe single-feature polymorphisms (mSFPs) and 638 recombination events (496 excluding those from subtelomeric regions). These data, in combination with results from 254 previously reported microsatellites, enabled us to construct a high-resolution genetic map. Comparing genetic and physical maps, we obtained an overall recombination rate of 9.6 kb/cM (12.8 kb/cM excluding subtelomeric regions) and identified 54 hotspots, some of which occurred in genes encoding surface antigens or proteins with repetitive motifs that might play a role in genetic recombination in the parasite. Motifs enriched in hotspots were also identified. In agreement with results from a previous cross (HB3 M-BM-4 Dd2), there was positive correlation between sizes of individual chromosomes and their recombination events. These results show that the P. falciparum genome is highly recombinogenic, providing an important genetic basis for parasite survival under various selection pressures. GC-rich repetitive motifs identified in the hotspot sequences may play a role in the high recombination frequency observed. Ten microgram of genomic DNA, extracted and purified from 3D7 (reference), thirty-two P. falciparum independent recombinant progeny of the 7G8 x GB4 cross, and the two parental lines (Hayton, 2008), were hybridized to the PFSANGER GenechipM-BM-. (Affymetrix, Inc., Santa Clara, CA, USA). The scanned image CEL files were first processed using the RMA method, then averaged and compared with reference genome 3D7, and lastly assigned either 7G8 or GB4 alleles based on similarities to the two parental lines. Total of 35 genomic DNA samples (biological replicates: 6 for 3D7, 4 for 7G8, 4 for GB4, and 2 for Pf_WE2). The supplementary file 'GSE25656_QuantNormData_Log2_AllSamples.txt' contains the RMA-normalized data for all of the samples. The supplementary files 'GSE25656_chr*' contain the parental allele assignment of each chromosome and include probe-level annotation.
2011-03-16 | E-GEOD-25656 | biostudies-arrayexpress
Project description:The information about when and where each gene is to be expressed is mainly encoded in the DNA sequence of enhancers, sequence elements that comprise binding sites (motifs) for different transcription factors (TFs). Most of the research on enhancer sequences has been focused on TF motif presence, while the enhancer syntax, i.e. the flexibility of important motif positions and how the sequence context modulates the activity of TF motifs, remain poorly understood. Here, we explore the rules of enhancer syntax by a two-pronged approach in Drosophila melanogaster S2 cells: we (1) replace important motifs by an exhaustive set of all possible 65,536 eight-nucleotide-long random sequences and (2) paste eight important TF motif types into 763 motif positions within 496 enhancers. These complementary strategies reveal that enhancers display constrained sequence flexibility and the context-specific modulation of motif function. Important motifs can be functionally replaced by hundreds of sequences constituting several distinct motif types, but only a fraction of all possible sequences and motif types restore enhancer activity. Moreover, TF motifs contribute with different intrinsic strengths that are strongly modulated by the enhancer sequence context (the flanking sequence, presence and diversity of other motif types, and distance between motifs), such that not all motif types can work in all positions. Constrained sequence flexibility and the context-specific modulation of motif function are also hallmarks of human enhancers and TF motifs, as we demonstrate experimentally. Overall, these two general principles of enhancer sequences are important to understand and predict enhancer function during development, evolution and in disease.
2022-12-15 | GSE211655 | GEO
Project description:We used a high-density tiling array to estimate genetic recombination rate among 32 independent recombinant progeny of a P. falciparum genetic cross (7G8 × GB4). We detected 3184 segregating multi-probe single-feature polymorphisms (mSFPs) and 638 recombination events (496 excluding those from subtelomeric regions). These data, in combination with results from 254 previously reported microsatellites, enabled us to construct a high-resolution genetic map. Comparing genetic and physical maps, we obtained an overall recombination rate of 9.6 kb/cM (12.8 kb/cM excluding subtelomeric regions) and identified 54 hotspots, some of which occurred in genes encoding surface antigens or proteins with repetitive motifs that might play a role in genetic recombination in the parasite. Motifs enriched in hotspots were also identified. In agreement with results from a previous cross (HB3 ´ Dd2), there was positive correlation between sizes of individual chromosomes and their recombination events. These results show that the P. falciparum genome is highly recombinogenic, providing an important genetic basis for parasite survival under various selection pressures. GC-rich repetitive motifs identified in the hotspot sequences may play a role in the high recombination frequency observed.
2011-03-16 | GSE25656 | GEO
Project description:In this study, we present the first genome-wide recombination map for mitochondrial DNA in yeast. We also assess the impact of the genetic background and of several gene deletions on the recombination profiles.
2014-10-22 | E-MTAB-2474 | biostudies-arrayexpress
Project description:Mapping mitochondrial DNA recombination in yeast
| PRJEB6084 | ENA