Changes in the DNase I sensitivity of DNA sequences within the yeast 2 μm plasmid nucleoprotein complex effected by plasmid-encoded products

Fagrelius, Thomas J.; Strand, Andrew D.; Livingston, Dennis

doi:10.1016/0022-2836(87)90555-9

Cited by 7 publications

(6 citation statements)

References 20 publications

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“…Much of the normal REP function is retained, since the Rep' chimeric plasmids CV20 and CV21 are 10-to 20-fold more stable than their Rep-derivatives. Moreover, they retain a chromatin organization very similar to that of the native plasmid, whereas Rep-plasmids exhibit several significant differences (8,43). Finally, the transcription profiles of Rep' chimeric plasmids are both qualitatively and quantitatively similar to that of the native 2Rm plasmid, in contrast to the elevated levels observed with Rep-derivatives.…”

Section: Resultsmentioning

confidence: 59%

“…For chromosomal sequences, forces generated by centromeres would be suffi-VOL. 8,1988 on May 12, 2018 by guest http://mcb.asm.org/ Downloaded from cient to overcome interactions with the transcription apparatus and thus assure equal partition at nuclear division.…”

Section: Resultsmentioning

confidence: 99%

“…It was of interest to determine whether there are changes in the levels of transcripts initiating in or near the REP3 locus, since both genetic (21,24) and physical (8,43) findings indicate that the REP gene products interact with this region. We used a probe that is specific for part of REP3 and for D antisense RNA (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Copy number and partition of the Saccharomyces cerevisiae 2 micron plasmid controlled by transcription regulators.

Veit¹,

Fangman²

1988

Mol. Cell. Biol.

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The 2,m plasmid of Saccharomyces cerevisiae is maintained by the action of plasmid-encoded gene products that control copy number and promote equipartition of plasmid copies at cell division. We show that the REP) and REP2 plasmid-encoded gene products are master regulators that act in concert to autoregulate the level of their own transcripts and to regulate transcript levels of the FLP gene that promotes plasmid copy amplification. REP) and REP2 are also shown to repress transcription at REP3, the cis-acting site essential for plasmid equipartitioning. We propose a model in which REP3 acts by dislodging transcription apparatuses that otherwise cause plasmid molecules to adhere to the mother nucleus and segregate asymmetrically. On the basis of their ability to generate specific chromatin structures, we also propose that the REP] and REP2 gene products interact with different specific sequences found iterated in the 2ILm plasmid.The 2,m plasmid is a 6.3-kilobase (kb) multicopy circular DNA found in most strains of S. cerevisiae (2,3,12,30). Because the plasmid confers no selective advantage to its host, it must rely on an efficient maintenance system. The rate at which cells lacking 2,um (ciro cells) are generated, approximately 10-4 to 10-5 per cell per generation (13), indicates an aggregate stability comparable with that of individual chromosomes (16). The chromosomally encoded nuclear replication apparatus contributes to plasmid maintenance. Mutations or inhibitors that block chromosomal replication similarly affect the 2,m plasmid (26). Like chromosomes, each of the 50 to 100 copies of the 2ixm plasmid replicates once during S phase (46). Once replicated, however, plasmid and chromosomal DNAs appear to be partitioned within the dividing nucleus by distinct mechanisms. Whereas the partition of chromosomes is mediated by centromeric sequences (10), the 2,um plasmid relies on an apparently unrelated cis-acting element, REP3. As defined by its ability to enhance the stability of chimeric derivatives of the 2,m plasmid, REP3 function requires at least two of five 62-base-pair (bp) tandemly repeated sequences (21,22). This locus appears to correspond to the STB locus (24) for which sequences flanking the 62-bp repeats were also found necessary for stabilization. Recent work suggests that flanking sequences may enhance REP3 function by preventing transcription through the direct repeats (32).The stabilization of the 2,um plasmid by REP3 requires two trans-acting plasmid genes, REP] and REP2 (5,21,24,43 (46). Moreover, the REP system is able to stabilize plasmids in the absence of FLP-catalyzed recombination. It therefore seems that the REP3-mediated stabilization reflects a more equal distribution of plasmid copies at division rather than correction of an initially biased distribution.In a previous study (43) In this study, we have used two approaches to document the negative regulation of FLP and other plasmid gene transcript levels by REP gene products. We first describe increases in transcript levels that res...

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Section: Resultsmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 99%

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Copy number and partition of the Saccharomyces cerevisiae 2 micron plasmid controlled by transcription regulators.

Veit¹,

Fangman²

1988

Mol. Cell. Biol.

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“…Previous analyses employing DNase I and micrococcal nuclease digestion suggested that the organization of STB chromatin, which appears to have a relatively low occupancy of nucleosomes, is modulated by the Rep1 protein and the RSC2 chromatin-remodeling complex (12,46,50). The size of STBproximal or STB-distal, ϳ300 bp, can accommodate one or two standard H3-containing or Cse4-containing nucleosomes, which wrap ϳ150 bp and ϳ125 bp of DNA, respectively, around them.…”

Section: Fig 4 Scm3 Interacts With Stb and Promotes Cse4-stb Associmentioning

confidence: 99%

Cse4 (CenH3) Association with the Saccharomyces cerevisiae Plasmid Partitioning Locus in Its Native and Chromosomally Integrated States: Implications in Centromere Evolution

Huang

Hajra

Ghosh

et al. 2011

Molecular and Cellular Biology

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The histone H3 variant Cse4 specifies centromere identity in Saccharomyces cerevisiae by its incorporation into a special nucleosome positioned at CEN DNA and promotes the assembly of the kinetochore complex, which is required for faithful chromosome segregation. Our previous work showed that Cse4 is also associated with the partitioning locus STB of the 2m circle-a multicopy plasmid that resides in the yeast nucleus and propagates itself stably. Cse4 is essential for the functional assembly of the plasmid partitioning complex, including the recruitment of the yeast cohesin complex at STB. We have located Cse4 association strictly at the origin-proximal subregion of STB. Three of the five directly repeated tandem copies of a 62-bp consensus sequence element constituting this region are necessary and sufficient for the recruitment of Cse4. The association of Cse4 with STB is dependent on Scm3, the loading factor responsible for the incorporation of Cse4 into the CEN nucleosome. A chromosomally integrated copy of STB confers on the integration site the capacity for Cse4 association as well as cohesin assembly. The localization of Cse4 in chromatin digested by micrococcal nuclease is consistent with the potential assembly of one Cse4-containing nucleosome, but not more than two, at STB. The remarkable ability of STB to acquire a very specialized, and strictly regulated, chromosome segregation factor suggests its plausible evolutionary kinship with CEN.The 2m plasmid of Saccharomyces cerevisiae is an example of a highly optimized, circular, multicopy extrachromosomal selfish DNA element (25,27,49). The plasmid does not seem to contribute to the host's fitness under standard laboratory growth conditions. However, at its steady-state copy number of 40 to 60 molecules per cell, any growth disadvantage imposed by the plasmid is rather small (16,30). The most remarkable attribute of this selectively almost neutral entity is its ability to propagate with nearly chromosome-like stability at its steadystate copy number. The entire genetic makeup of the 2m circle is devoted to three functions: efficient replication by the host machinery, equal segregation, and maintenance of the copy number. The plasmid accomplishes these goals with minimal metabolic encumbrance to its host.Direct visualization of fluorescence-tagged reporter plasmids in live cells suggests that 2m circle molecules are organized in the nucleus as 3 to 5 dynamic foci that form a closeknit cluster (47). The plasmid also segregates as a clustered entity; sister clusters part from each other and move away at the anaphase stage of the cell cycle. Population analysis and time lapse assays have revealed close similarities between the 2m circle and the yeast chromosomes or a centromere plasmid (minichromosome) in their dynamics and kinetics of segregation (17, 47). The relevant inference from a variety of experiments is that plasmid segregation is tightly coupled to chromosome segregation, perhaps by attachment of duplicated plasmid clusters to a pair of sister chro...

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“…It has been concluded that the existence of the HS 3' to the D reading frame requires the products of REPI, REP2and D genes. 33 On the other hand, Veit and F a n g r~~a n '~~ concluded that the product of REPI gene alone is responsible for the chromatin structure of the REP3 region, whereas the hypersensitive site 5' to the FLP gene requires the presence of both the REP1 and REP2 products. The autonomy of 2 pm plasmid in regard to its chromatin structure, has thereby allowed the analysis of the protein factors required to generate DNase I hypersensitivity.…”

Section: Hypersensitive Sitesmentioning

confidence: 99%

Chromatin structure of yeast genes

Pérez‐Ortín

Matallana

Franco

1989

Yeast

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Changes in the DNase I sensitivity of DNA sequences within the yeast 2 μm plasmid nucleoprotein complex effected by plasmid-encoded products

Cited by 7 publications

References 20 publications

Copy number and partition of the Saccharomyces cerevisiae 2 micron plasmid controlled by transcription regulators.

Copy number and partition of the Saccharomyces cerevisiae 2 micron plasmid controlled by transcription regulators.

Cse4 (CenH3) Association with the Saccharomyces cerevisiae Plasmid Partitioning Locus in Its Native and Chromosomally Integrated States: Implications in Centromere Evolution

Chromatin structure of yeast genes

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