Sir2 suppresses transcription-mediated displacement of Mcm2-7 replicative helicases at the ribosomal DNA repeats
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ABSTRACT:
PROVIDER: PRJNA534498 | ENA |
REPOSITORIES: ENA
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Project description:Repetitive DNA sequences within eukaryotic heterochromatin are poorly transcribed and replicate late in S-phase. In Saccharomyces cerevisiae, the histone deacetylase Sir2 is required for both transcriptional silencing and late replication at the repetitive ribosomal DNA arrays (rDNA). Despite the widespread association between transcription and replication, it remains unclear how transcription might impinge on replication, or vice versa. Here we show that, when silencing of an RNA polymerase II (RNA Pol II)-transcribed non-coding RNA at the rDNA is disrupted by SIR2 deletion, RNA polymerase pushes and thereby relocalizes replicative Mcm2-7 helicases away from their loading sites to an adjacent region with low nucleosome occupancy, and this relocalization is associated with increased rDNA origin efficiency. Our results suggest a model in which two of the major defining features of heterochromatin, transcriptional silencing and late replication, are mechanistically linked through suppression of polymerase-mediated displacement of replication initiation complexes.
2019-05-08 | GSE130273 | GEO
Project description: Not available
| S-EPMC6532929 | biostudies-literature
Project description:The loading and activation of the replicative helicase MCM2-7 are key events during the G1-S phase transition.In budding yeast, the origin recognition complex (ORC) binds to the conserved DNA elements A and B1 of the autonomously replicating sequence (ARS).This is followed by the consecutive loading of two MCM2-7 hetero-hexamers into a MCM2-7 double-hexamer(DH).In S-phase the MCM2-7DH is activated, resulting in two Cdc45-MCM-GINS(CMG) helicases that bidirectionally unwind DNA ahead of the replication fork.Here,we show that MCM2-7 helicase loading across the B1 element displaces ORC fromo rigins.This allows ORC binding and helicase loading at lower affinity binding sites and origins throughout the genome.Furthermore, we mapped the sites of initial DNA unwinding genome-wide and show that these sites appear near the N-terminal domains of the MCM2-7 double-hexamer in proximity of the B1 element.Finally, employing a chemical-biology approach, we establish that during helicase activation the Mcm2/5 interface acts as the DNA exit gate for single-stranded-DNA extrusion.Our work identifies that helicase loading follows a distributive mechanism, allowing for equal MCM2-7 loading across the genome and surprisingly finds that DNA unwinding initiates from the helicase N-terminal interface in proximity to the ARS B1 element.
2024-06-21 | GSE240472 | GEO
Project description:Chromatin immunoprecipitation of the MCM2-7 replicative helicase followed by hybridization to genome-wide tiling microarrays demonstrated that MCMs localize to the follicle cell amplicons at stages of replication initiation Comparison of MCM2-7 ChIP sample compared to input DNA for Drosophila egg chambers
2011-09-06 | E-GEOD-31889 | biostudies-arrayexpress
Project description:The loading and activation of the replicative helicase MCM2-7 are key events during the G1-S phase transition. In budding yeast, the origin recognition complex (ORC) binds to the conserved DNA elements A and B1 of the autonomously replicating sequence (ARS). This is followed by the consecutive loading of two MCM2-7 hetero-hexamers into a MCM2-7 double-hexamer (DH). In S-phase the MCM2-7 DH is activated, resulting in two Cdc45-MCM-GINS (CMG) helicases that bidirectionally unwind DNA ahead of the replication fork. Here, we show that MCM2-7 helicase loading across the B1 element displaces ORC from origins. This allows ORC binding and helicase loading at lower affinity binding sites and origins throughout the genome. Furthermore, we mapped the sites of initial DNA unwinding genome-wide and show that these sites appear near the N-terminal domains of the MCM2-7 double-hexamer in proximity of the B1 element. Finally, employing a chemical-biology approach, we establish that during helicase activation the Mcm2/5 interface acts as the DNA exit gate for single-stranded-DNA extrusion. Our work identifies that helicase loading follows a distributive mechanism, allowing for equal MCM2-7 loading across the genome and surprisingly finds that DNA unwinding initiates from the helicase N-terminal interface in proximity to the ARS B1 element.
2024-06-21 | GSE173527 | GEO
Project description:Chromatin immunoprecipitation of the MCM2-7 replicative helicase followed by hybridization to genome-wide tiling microarrays demonstrated that MCMs localize to the follicle cell amplicons at stages of replication initiation
2011-09-07 | GSE31889 | GEO
Project description:Eukaryotic genomes are replicated from many origin sites that are licensed by the loading of inactive double hexamers of the replicative DNA helicase, Mcm2-7. How eukaryotic origin positions are specified remains elusive. Here we show that, contrary to the bacterial paradigm, eukaryotic origins are not irrevocably defined by selection of the loading site for the replicative helicase, but can shift in position after helicase loading. Using purified proteins, we show that DNA translocases, including RNA polymerase, can push budding yeast Mcm2-7 double hexamers along DNA. Displaced Mcm2-7 double hexamers support DNA replication initiation distal to the loading site in vitro. In yeast cells that are defective for transcription termination, collisions with RNA polymerase induce a shift in origin positions that correlates with the direction of transcription. These results reveal a eukaryotic origin specification mechanism that departs from the classical replicon model, helping eukaryotic cells to negotiate transcription-replication conflict. 4 samples: one replicate for WT at 37C, two replicates for rat1-1 at 37C, and one replicate for rat1-1 at 24C. All are single-end sequenced via Ion Torrent PGM methodology. rat1 = Nuclear 5' to 3' single-stranded RNA exonuclease; involved in RNA metabolism (http://www.yeastgenome.org/locus/S000005574/overview). 4 ChIP seq samples and their duplicates are submitted. rat1-1 ORC ChIP at 24C and 37C; rat1-1 MCM ChIP at 24C and 37C.
2016-01-07 | E-GEOD-69065 | biostudies-arrayexpress
Project description:Mcm2-7 ChIP in pre-meiotic and pre-mitotic cells, axis factor ChIP in wild-type and replication compromised strains in meiosis Multiple studies of meiotic chromosomes were undertaken. To study DNA replication, the locations of replicative helicase (Mcm2-7) were mapped in pre-meiotic and pre-mitotic cells, and DNA replication profiles were created for pre-meiotic S (meiS) and pre-mitotic S (mitS) phases. Early origins were mapped in hydroxyurea for wild-type cells in mitS + 200mM HU, and meiS +20mM HU for wild-type, sml1, rec8 and spo11 deletion cells. Rec8, Hop1 and Red1 binding to meiotic chromosomes was evaluated using ChIP-chip in wild-type cells with and without 20 mM HU, and in cdc6-mn and clb5 clb6 delete cells. Finally, meiotic DNA double-strand breaks (DSBs) were mapped in cdc6-mn dmc1 delete cells by measuring the ssDNA that accumulates at DSB hotspots.
2012-06-18 | E-GEOD-35658 | biostudies-arrayexpress
Project description:Eukaryotic genomes are replicated from many origin sites that are licensed by the loading of inactive double hexamers of the replicative DNA helicase, Mcm2-7. How eukaryotic origin positions are specified remains elusive. Here we show that, contrary to the bacterial paradigm, eukaryotic origins are not irrevocably defined by selection of the loading site for the replicative helicase, but can shift in position after helicase loading. Using purified proteins, we show that DNA translocases, including RNA polymerase, can push budding yeast Mcm2-7 double hexamers along DNA. Displaced Mcm2-7 double hexamers support DNA replication initiation distal to the loading site in vitro. In yeast cells that are defective for transcription termination, collisions with RNA polymerase induce a shift in origin positions that correlates with the direction of transcription. These results reveal a eukaryotic origin specification mechanism that departs from the classical replicon model, helping eukaryotic cells to negotiate transcription-replication conflict.
2016-01-07 | GSE69065 | GEO
Project description:Determination of the genome-wide distribution of the Mcm2-7 helicase by chromatin immunoprecipitation in the Drosophila Kc167 cell line at the beginning of S phase. Kc167 cells were arrested at the G1/S transition with hydroxyurea (HU). Goal was to evaluate changes in the genome-wide Mcm2-7 distribution throughout the cell cycle, and how this relates to the excess Mcm2-7 loaded onto chromatin in G1. ChIP-Chip of Mcm2-7 in HU compared to input genomic DNA. Biological Replicates: 2
2014-11-27 | E-GEOD-63680 | biostudies-arrayexpress