Fob1-dependent condensin recruitment and loop extrusion on yeast chromosome III [Micro-C seq]
Ontology highlight
ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
PROVIDER: GSE198148 | GEO | 2023/03/23
REPOSITORIES: GEO
Similar Datasets
Project description:Saccharomyces cerevisiae switches its mating type (MATa or MATalpha) through gene conversion using one of two possible donors, HMLalpha or HMRa, both of which are maintained by the SIR silencing complex as heterochromatic cassettes on opposing ends of chromosome III. In MATa cells, HMLalpha on the left arm is preferentially chosen as the donor through a mechanism requiring a cis-acting sequence called the recombination enhancer (RE). The left half of the RE is required for this donor preference activity, whereas the right half has been implicated in regulating chromosome III structure. In this study we have identified a MATa-specific Sir2 and condensin binding site within the right half of the RE that maintains chromosome III in a switching-competent conformation by preventing MATa from interacting with the default HMRa donor on the right arm. Within the RE, Sir2 strongly represses transcription of a small MATa-specific gene of unknown function (RDT1). Upon expression of HO endonuclease to induce the switching process, Sir2 redistributes from the RE to the double-stranded DNA break site at MATa, thus derepressing RDT1 transcription to coincide with the timing of mating-type switching. Condensin is also displaced from the RE in response to the HO-induced break, likely contributing to the transient change in chromosome III conformation required for effective switching without disruption of HML and HMR heterochromatin.
2019-05-23 | GSE92715 | GEO
Project description:Saccharomyces cerevisiae switches its mating type (MATa or MATalpha) through gene conversion using one of two possible donors, HMLalpha or HMRa, both of which are maintained by the SIR silencing complex as heterochromatic cassettes on opposing ends of chromosome III. In MATa cells, HMLalpha on the left arm is preferentially chosen as the donor through a mechanism requiring a cis-acting sequence called the recombination enhancer (RE). The left half of the RE is required for this donor preference activity, whereas the right half has been implicated in regulating chromosome III structure. In this study we have identified a MATa-specific Sir2 and condensin binding site within the right half of the RE that maintains chromosome III in a switching-competent conformation by preventing MATa from interacting with the default HMRa donor on the right arm. Within the RE, Sir2 strongly represses transcription of a small MATa-specific gene of unknown function (RDT1). Upon expression of HO endonuclease to induce the switching process, Sir2 redistributes from the RE to the double-stranded DNA break site at MATa, thus derepressing RDT1 transcription to coincide with the timing of mating-type switching. Condensin is also displaced from the RE in response to the HO-induced break, likely contributing to the transient change in chromosome III conformation required for effective switching without disruption of HML and HMR heterochromatin.
2019-05-23 | GSE92714 | GEO
Project description:Purpose: To identify cohibin-dependent condensin binding sites throughout the yeast genome. Conclusions: This ChIP-seq experiment showed that the condensin subunit, Brn1, was depleted from the RDT1 promoter in an lrs4Δ mutant strain. The experiment also showed that the Lrs4 subunit of the cohibin complex is highly enriched at the RDT1 promoter on chromosome III.
2023-03-23 | GSE198161 | GEO
Project description:Fob1-dependent condensin recruitment and loop extrusion on yeast chromosome III [Micro-C seq]
| PRJNA813866 | ENA
Project description:Condensins are broadly conserved chromosome organizers that function in chromatin compaction and transcriptional regulation, but to what extent these two functions are linked has remained unclear. Here, we analyzed the effect of condensin inactivation on genome compaction and global gene expression in the yeast Saccharomyces cerevisiae. Spike-in-controlled 3C-seq analysis revealed that acute condensin inactivation led to a global decrease in close-range chromosomal interactions as well as more specific losses of homotypic tRNA gene clustering. In addition, we identified a condensin-rich topologically associated domain between the ribosomal DNA and the centromere on chromosome XII that is lost upon condensin inactivation. Unexpectedly, these large-scale changes in chromosome architecture were not associated with global changes in transcript levels as determined by spike-in-controlled mRNA-seq analysis. Our data suggest that the global transcriptional program of S. cerevisiae is resistant to condensin inactivation and the associated profound changes in genome organization.
2017-10-25 | GSE106104 | GEO
Project description:To separate replicated sister chromatids during mitosis, eukaryotes and prokaryotes have structural maintenance of chromosome (SMC) condensin complexes that were recently shown to organize chromosomes by a process known as DNA loop extrusion. In rapidly dividing bacterial cells, the process of separating sister chromatids occurs concomitantly with ongoing transcription. How transcription interferes with the condensin loop extrusion process is largely unexplored, but recent experiments show that sites of high transcription may directionally affect condensin loop extrusion. We quantitatively investigate different mechanisms of interaction between condensin and elongating RNA polymerases (RNAP) and find that RNAPs are likely steric barriers that can push and interact with condensins. Supported by new Hi-C and ChIP-seq data for cells after transcription inhibition and RNAP degradation, we argue that translocating condensins must bypass transcribing RNAPs within ~2 seconds of an encounter at rRNA genes and within ~10 seconds at protein coding genes. Thus, while individual RNAPs have little effect on the progress of loop extrusion, long, highly transcribed operons can significantly impede the extrusion process. Our data and quantitative models further suggest that bacterial condensin loop extrusion occurs by two independent, uncoupled motor activities; the motors translocate on DNA in opposing directions and function together to enlarge chromosomal loops, each independently bypassing steric barriers in their path. Our study provides a quantitative link between transcription and 3D genome organization and proposes a mechanism of interactions between SMC complexes and elongating transcription machinery relevant from bacteria to higher eukaryotes.
2019-09-23 | GSE117854 | GEO
Project description:Inspection of Hi-C and ChIP-seq data suggests that condensin DC is an X-chromosome enriched loop extruder that stalls at rex sites. Insertion of rex site on X-chromosome suggests orientation independent barrier function of rex sites. Insertion of rex site on chromosome-II results in recruitment and spreading of condensin DC that coincides with TAD formation.
2022-06-14 | GSE206065 | GEO
Project description:SMC condensin complexes play a central role in compacting and resolving replicated chromosomes in virtually all organisms yet how they accomplish this remains elusive. In Bacillus subtilis, condensin is loaded at centromeric parS sites, where it encircles DNA and individualizes newly replicated origins. Using chromosome conformation capture and cytological assays, we show that condensin recruitment to origin-proximal parS sites is required for the juxtaposition of the two chromosome arms. Recruitment to ectopic parS sites promotes alignment of large tracks of DNA flanking these sites. Importantly, insertion of parS sites on opposing arms indicates that these ?zip-up? interactions only occur between adjacent DNA segments. Collectively, our data suggest that condensin resolves replicated origins by promoting the juxtaposition of DNA flanking parS sites drawing sister origins in on themselves and away from each other. These results are consistent with a model in which condensin encircles the DNA flanking its loading site and then slides down, tethering the two arms together. Lengthwise condensation via loop-extrusion could provide a generalizable mechanism by which condensin acts dynamically to individualize origins in B. subtilis and, when loaded along eukaryotic chromosomes, to resolve them during mitosis.
2015-08-12 | GSE68418 | GEO
Project description:Condensins are molecular motors that compact DNA for chromosome segregation and gene regulation. In vitro experiments have begun to elucidate the mechanics of condensin function but how condensin loading and translocation along DNA controls eukaryotic chromosome structure in vivo remains poorly understood. To address this question, we took advantage of a specialized condensin, which organizes the 3D conformation of X chromosomes to mediate dosage compensation (DC) in C. elegans. Condensin DC is recruited and spreads from a small number of recruitment elements on the X chromosome (rex). We found that ectopic insertion of rex sites on an autosome leads to bidirectional spreading of the complex over hundreds of kilobases. On the X chromosome, strong rex sites contain multiple copies of a 12-bp sequence motif and act as TAD borders. Inserting a strong rex and ectopically recruiting the complex on the X chromosome or an autosome creates a loop-anchored TAD. Unlike the CTCF system, which controls TAD formation by cohesin, direction of the 12-bp motif does not control the specificity of loops. In an X;V fusion chromosome, condensin DC linearly spreads into V and increases 3D DNA contacts, but fails to form TADs in the absence of rex sites. Finally, we provide in vivo evidence for the loop extrusion hypothesis by targeting multiple dCas9-Suntag complexes to an X chromosome repeat region. Consistent with linear translocation along DNA, condensin DC accumulates at the block site. Together, our results support a model whereby strong rex sites act as insulation elements through recruitment and bidirectional spreading of condensin DC molecules and form loop-anchored TADs.
2021-03-24 | GSE169468 | GEO
Project description:Condensins are molecular motors that compact DNA for chromosome segregation and gene regulation. In vitro experiments have begun to elucidate the mechanics of condensin function but how condensin loading and translocation along DNA controls eukaryotic chromosome structure in vivo remains poorly understood. To address this question, we took advantage of a specialized condensin, which organizes the 3D conformation of X chromosomes to mediate dosage compensation (DC) in C. elegans. Condensin DC is recruited and spreads from a small number of recruitment elements on the X chromosome (rex). We found that ectopic insertion of rex sites on an autosome leads to bidirectional spreading of the complex over hundreds of kilobases. On the X chromosome, strong rex sites contain multiple copies of a 12-bp sequence motif and act as TAD borders. Inserting a strong rex and ectopically recruiting the complex on the X chromosome or an autosome creates a loop-anchored TAD. Unlike the CTCF system, which controls TAD formation by cohesin, direction of the 12-bp motif does not control the specificity of loops. In an X;V fusion chromosome, condensin DC linearly spreads into V and increases 3D DNA contacts, but fails to form TADs in the absence of rex sites. Finally, we provide in vivo evidence for the loop extrusion hypothesis by targeting multiple dCas9-Suntag complexes to an X chromosome repeat region. Consistent with linear translocation along DNA, condensin DC accumulates at the block site. Together, our results support a model whereby strong rex sites act as insulation elements through recruitment and bidirectional spreading of condensin DC molecules and form loop-anchored TADs.
2021-03-24 | GSE169250 | GEO