Determinants of Sir2-Mediated, Silent Chromatin Cohesion

Chen, Yu-Fan; Chou, Chia-Ching; Gartenberg, Marc R.

doi:10.1128/mcb.00057-16

Cited by 4 publications

(2 citation statements)

References 62 publications

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“…With regard to cohesin, one study showed that mutations in the cohesin loading complex did not affect repression of reporter genes within the NTS elements (Gard et al 2009). In another study, separation-of-function mutations of SIR2 that abolished cohesion of the mating-type loci had no impact on silencing there or at the rDNA (Chen et al 2016). Thus, the evidence suggests that while Sir2 is required for cohesion; cohesion is not required for silencing.…”

Section: Intracellular Competition For Limiting Amounts Of Sir2mentioning

confidence: 98%

“…Cohesin action at silent loci is regulated by the extreme C-terminal of Sir2 (Wu et al 2011). Interestingly, silencing persists in a sir2 mutant that blocks cohesion but still recruits cohesin to chromatin (Chen et al 2016). This result indicates that cohesion is dispensable for silencing even if the cohesin complex is not.…”

Section: Potential Cell Cycle Regulators Of Silent Chromatin Establismentioning

confidence: 99%

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The Nuts and Bolts of Transcriptionally Silent Chromatin in Saccharomyces cerevisiae

2016

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Transcriptional silencing in Saccharomyces cerevisiae occurs at several genomic sites including the silent mating-type loci, telomeres, and the ribosomal DNA (rDNA) tandem array. Epigenetic silencing at each of these domains is characterized by the absence of nearly all histone modifications, including most prominently the lack of histone H4 lysine 16 acetylation. In all cases, silencing requires Sir2, a highly-conserved NAD + -dependent histone deacetylase. At locations other than the rDNA, silencing also requires additional Sir proteins, Sir1, Sir3, and Sir4 that together form a repressive heterochromatin-like structure termed silent chromatin. The mechanisms of silent chromatin establishment, maintenance, and inheritance have been investigated extensively over the last 25 years, and these studies have revealed numerous paradigms for transcriptional repression, chromatin organization, and epigenetic gene regulation. Studies of Sir2-dependent silencing at the rDNA have also contributed to understanding the mechanisms for maintaining the stability of repetitive DNA and regulating replicative cell aging. The goal of this comprehensive review is to distill a wide array of biochemical, molecular genetic, cell biological, and genomics studies down to the "nuts and bolts" of silent chromatin and the processes that yield transcriptional silencing.

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Section: Intracellular Competition For Limiting Amounts Of Sir2mentioning

confidence: 98%

Section: Potential Cell Cycle Regulators Of Silent Chromatin Establismentioning

confidence: 99%

The Nuts and Bolts of Transcriptionally Silent Chromatin in Saccharomyces cerevisiae

2016

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Collaborations between chromatin and nuclear architecture to optimize DNA repair fidelity

Mackenroth

Alani

2021

DNA Repair

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Binding, sliding, and function of cohesin during transcriptional activation

Borrie

Campor

Joshi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The ring-shaped cohesin complex orchestrates long-range DNA interactions to mediate sister chromatid cohesion and other aspects of chromosome structure and function. In the yeast Saccharomyces cerevisiae, the complex binds discrete sites along chromosomes, including positions within and around genes. Transcriptional activity redistributes the complex to the 3′ ends of convergently oriented gene pairs. Despite the wealth of information about where cohesin binds, little is known about cohesion at individual chromosomal binding sites and how transcription affects cohesion when cohesin complexes redistribute. In this study, we generated extrachromosomal DNA circles to study cohesion in response to transcriptional induction of a model gene, URA3. Functional cohesin complexes loaded onto the locus via a poly(dA:dT) tract in the gene promoter and mediated cohesion before induction. Upon transcription, the fate of these complexes depended on whether the DNA was circular or not. When gene activation occurred before DNA circularization, cohesion was lost. When activation occurred after DNA circularization, cohesion persisted. The presence of a convergently oriented gene also prevented transcription-driven loss of functional cohesin complexes, at least in M phase-arrested cells. The results are consistent with cohesin binding chromatin in a topological embrace and with transcription mobilizing functional complexes by sliding them along DNA.T he protein complex known as cohesin organizes eukaryotic genomes into structures that segregate faithfully between dividing cells. The complex was first discovered for its role in mediating sister chromatid cohesion, but it is now known to participate in numerous aspects of chromosome biology (1, 2). Cohesin is clinically relevant because mutations in subunits of the complex or in factors that load and activate the complex lead to developmental disorders such as Cornelia de Lange syndrome, Roberts syndrome, and Warsaw breakage syndrome (3, 4).Cohesin is a ring-shaped complex composed of four subunits named Smc1, Smc3, Scc3, and Mcd1/Scc1 in budding yeast. The complex is thought to embrace DNA topologically with chromatin fibers passing through a central open channel (5-7). A substantial body of work supports a model in which cohesion arises from single cohesin complexes that embrace both sister chromatids [the double embrace model (6)]. Whether the central channel is large enough to accommodate both chromatids has recently been brought into question (8). In addition, the behavior of cohesin has not always been consistent with a double embrace by single complexes (for examples, see refs. 9-11). These situations usually involve a perturbation that causes loss of cohesion but not a loss of cohesin binding from chromatin. Such results force consideration of alternative models in which cohesin complexes embrace only one chromatid topologically and interact with other cohesin complexes or chromatin features to mediate cohesion (9,11,12).Cohesin binds densely in centromeric regions of chromos...

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Determinants of Sir2-Mediated, Silent Chromatin Cohesion

Cited by 4 publications

References 62 publications

The Nuts and Bolts of Transcriptionally Silent Chromatin in Saccharomyces cerevisiae

The Nuts and Bolts of Transcriptionally Silent Chromatin in Saccharomyces cerevisiae

Collaborations between chromatin and nuclear architecture to optimize DNA repair fidelity

Binding, sliding, and function of cohesin during transcriptional activation

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