Similar Datasets
Project description:Replication forks terminate at TERs and telomeres. Forks that converge or encounter transcription generate topological stress. Combining genetic, genomic and imaging approaches we found that Rrm3hPif1 and Sen1hSenataxin helicases assist termination at TERs, Sen1 at telomeres. rrm3 and sen1 are synthetic lethal, fail to terminate replication exhibiting lagging chromosomes and fragility at TERs and telomeres. sen1 rrm3 build up RNA-DNA hybrids at TERs, sen1 accumulates RNPII at TERs and telomeres. Double mutants exhibit X-shaped gapped or reversed converging forks. Rrm3 and Sen1 restrain Top1 and Top2 activities, preventing toxic accumulation of positive supercoil at TERs and telomeres. We suggest that Rrm3 and Sen1 coordinate the activities of fork-associated Top1 and Top2 with those of gene loop-associated Top1 and Top2 by preventing DNA and RNA polymerases slowing down when forks encounter transcription head-on or codirectionally, respectively. Hence Rrm3 and Sen1 are essential to generate permissive topological conditions for replication termination.
2022-10-11 | GSE214925 | GEO
Project description:Replication forks terminate at TERs and telomeres. Forks that converge or encounter transcription generate topological stress. Combining genetic, genomic and imaging approaches we found that Rrm3hPif1 and Sen1hSenataxin helicases assist termination at TERs, Sen1 at telomeres. rrm3 and sen1 are synthetic lethal, fail to terminate replication exhibiting lagging chromosomes and fragility at TERs and telomeres. sen1 rrm3 build up RNA-DNA hybrids at TERs, sen1 accumulates RNPII at TERs and telomeres. Double mutants exhibit X-shaped gapped or reversed converging forks. Rrm3 and Sen1 restrain Top1 and Top2 activities, preventing toxic accumulation of positive supercoil at TERs and telomeres. We suggest that Rrm3 and Sen1 coordinate the activities of fork-associated Top1 and Top2 with those of gene loop-associated Top1 and Top2 by preventing DNA and RNA polymerases slowing down when forks encounter transcription head-on or codirectionally, respectively. Hence Rrm3 and Sen1 are essential to generate permissive topological conditions for replication termination.
2022-10-11 | GSE214908 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2013-07-03 | E-GEOD-31962 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the SubSeries listed below.
2013-07-03 | GSE31962 | GEO
Project description:Faithful DNA replication with correct termination is essential for genome stability and transmission of genetic information. Here we have investigated the potential roles of Topoisomerase II (Top2) and the RecQ helicase Sgs1 during late stages of replication. We find that cells lacking Top2 and Sgs1 (or Top3) display two different characteristics during late S/G2 phase, checkpoint activation and accumulation of asymmetric X-structures, which are both independent of homologous recombination. Our data demonstrate that checkpoint activation is caused by a DNA structure formed at the strongest rDNA replication fork barrier (RFB) during replication termination, and consistently, checkpoint activation is dependent on the RFB binding protein, Fob1. In contrast, asymmetric X-structures are formed independent of Fob1 at less strong rDNA replication fork barriers. However, both checkpoint activation and formation of asymmetric X-structures are sensitive to conditions, which facilitate fork merging and progression of replication forks through replication fork barriers. Our data are consistent with a redundant role of Top2 and Sgs1 together with Top3 (Sgs1-Top3) in replication fork merging at rDNA barriers. At RFB either Top2 or Sgs1-Top3 is essential to prevent formation of a checkpoint activating DNA structure during termination, but at less strong rDNA barriers absence of the enzymes merely delays replication fork merging, causing an accumulation of asymmetric termination structures, which are solved over time.
| S-EPMC4668019 | biostudies-literature
Project description:Many non-coding transcripts (ncRNA) generated by RNA polymerase II in S. cerevisiae are terminated by the Nrd1-Nab3-Sen1 complex. However, Sen1 helicase levels are surprisingly low compared with Nrd1 and Nab3, raising questions regarding how ncRNA can be terminated in an efficient and timely manner. We show that Sen1 levels increase during the S and G2 phases of the cell cycle, leading to increased termination activity of NNS. Overexpression of Sen1 or failure to modulate its abundance by ubiquitin-proteasome-mediated degradation greatly decreases cell fitness. Sen1 toxicity is suppressed by mutations in other termination factors, and NET-seq analysis shows that its overexpression leads to a decrease in ncRNA production and altered mRNA termination. We conclude that Sen1 levels are carefully regulated to prevent aberrant termination. We suggest that ncRNA levels and coding gene transcription termination are modulated by Sen1 to fulfill critical cell cycle-specific functions.
| S-EPMC5919780 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2022-07-13 | GSE174738 | GEO
Project description:Extrinsic transcription termination typically involves remodeling of RNA polymerase by an accessory helicase. In yeast this is accomplished by the Sen1 helicase homologous to human senataxin (SETX). To gain insight into these processes we develop a DNA scaffold construct compatible with magnetic-trapping assays and from which S. cerevisiae RNA polymerase II (Pol II), as well as E. coli RNA polymerase (ecRNAP), can efficiently initiate transcription without transcription factors, elongate, and undergo extrinsic termination. By stalling Pol II TECs on the construct we can monitor Sen1-induced termination in real-time, revealing the formation of an intermediate in which the Pol II transcription bubble appears half-rewound. This intermediate requires ~40 sec to form and lasts ~20 sec prior to final dissociation of the stalled Pol II. The experiments enabled by the scaffold construct permit detailed statistical and kinetic analysis of Pol II interactions with a range of cofactors in a multi-round, high-throughput fashion.
| S-EPMC6449345 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2019-01-21 | GSE115028 | GEO
Project description:The essential helicase-like protein Sen1 mediates termination of RNA Polymerase II (Pol II) transcription at snoRNAs and other noncoding RNAs in yeast. A mutation in the Pol II subunit Rpb1 that increases the elongation rate increases read-through transcription at Sen1-mediated terminators. Termination and growth defects in sen1 mutant cells are partially suppressed by a slowly transcribing Pol II mutant and are exacerbated by a faster-transcribing Pol II mutant. Deletion of the nuclear exosome subunit Rrp6 allows visualization of noncoding RNA intermediates that are terminated but not yet processed. Sen1 mutants or faster-transcribing Pol II increase the average lengths of preprocessed snoRNA, CUT, and SUT transcripts, while slowed Pol II transcription produces shorter transcripts. These connections between transcription rate and Sen1 activity support a model whereby kinetic competition between elongating Pol II and Sen1 helicase establishes the temporal and spatial window for early Pol II termination.
| S-EPMC3545030 | biostudies-literature