scholarly journals The selfish yeast plasmid utilizes the condensin complex and condensed chromatin for faithful partitioning

PLoS Genetics ◽  
2021 ◽  
Vol 17 (7) ◽  
pp. e1009660
Author(s):  
Deepanshu Kumar ◽  
Hemant Kumar Prajapati ◽  
Anjali Mahilkar ◽  
Chien-Hui Ma ◽  
Priyanka Mittal ◽  
...  
Keyword(s):  
Plasmid Stability ◽  
Dna Amplification ◽  
Condensed Chromatin ◽  
Yeast Plasmid ◽  
Condensed Chromosome ◽  
Condensin Complex ◽  
2 Micron Plasmid ◽  
Stable Maintenance ◽  
Chromosome Iii ◽  
Persistence Strategies

Equipartitioning by chromosome association and copy number correction by DNA amplification are at the heart of the evolutionary success of the selfish yeast 2-micron plasmid. The present analysis reveals frequent plasmid presence near telomeres (TELs) and centromeres (CENs) in mitotic cells, with a preference towards the former. Inactivation of Cdc14 causes plasmid missegregation, which is correlated to the non-disjunction of TELs (and of rDNA) under this condition. Induced missegregation of chromosome XII, one of the largest yeast chromosomes which harbors the rDNA array and is highly dependent on the condensin complex for proper disjunction, increases 2-micron plasmid missegregation. This is not the case when chromosome III, one of the smallest chromosomes, is forced to missegregate. Plasmid stability decreases when the condensin subunit Brn1 is inactivated. Brn1 is recruited to the plasmid partitioning locus (STB) with the assistance of the plasmid-coded partitioning proteins Rep1 and Rep2. Furthermore, in a dihybrid assay, Brn1 interacts with Rep1-Rep2. Taken together, these findings support a role for condensin and/or condensed chromatin in 2-micron plasmid propagation. They suggest that condensed chromosome loci are among favored sites utilized by the plasmid for its chromosome-associated segregation. By homing to condensed/quiescent chromosome locales, and not over-perturbing genome homeostasis, the plasmid may minimize fitness conflicts with its host. Analogous persistence strategies may be utilized by other extrachromosomal selfish genomes, for example, episomes of mammalian viruses that hitchhike on host chromosomes for their stable maintenance.

scholarly journals Hitchhiking on condensed chromatin promotes plasmid persistence in yeast without perturbing chromosome function

2020 ◽  
Author(s):  
Hemant Kumar Prajapati ◽  
Deepanshu Kumar ◽  
Xian-Mei Yang ◽  
Chien-Hui Ma ◽  
Priyanka Mittal ◽  
...  
Keyword(s):  
Copy Number ◽  
Plasmid Stability ◽  
Dna Amplification ◽  
Condensed Chromatin ◽  
Plasmid Partitioning ◽  
Evolutionary Success ◽  
2 Micron Plasmid ◽  
Stable Maintenance ◽  
Chromosome Iii ◽  
Persistence Strategies

AbstractEquipartitioning by chromosome hitchhiking and copy number correction by DNA amplification are at the heart of the evolutionary success of the selfish yeast 2-micron plasmid. The present analysis reveals plasmid presence near centromeres and telomeres in mitotic cells, with a preference towards the latter. The observed correlation of plasmid missegregation with non-disjunction of rDNA and telomeres under Cdc14 inactivation, higher plasmid missegregation upon induced missegregation of chromosome XII but not chromosome III, requirement of condensin for plasmid stability and the interaction of the condensin subunit Brn1 with the plasmid partitioning system lend functional credence to condensed chromatin being favored for plasmid tethering. By homing to condensed/quiescent chromosome locales, and not over-perturbing genome homeostasis, the plasmid may minimize fitness conflicts with its host. Analogous persistence strategies may be utilized by other extrachromosomal selfish genomes, for example, episomes of mammalian viruses that also hitchhike on host chromosomes for their stable maintenance.

scholarly journals The 2 micron plasmid purloins the yeast cohesin complex

2002 ◽  
Vol 158 (4) ◽  
pp. 625-637 ◽  
Author(s):  
Shwetal Mehta ◽  
Xian Mei Yang ◽  
Clarence S. Chan ◽  
Melanie J. Dobson ◽  
Makkuni Jayaram ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Plasmid Stability ◽  
High Fidelity ◽  
Cohesin Complex ◽  
Plasmid Segregation ◽  
Rep Proteins ◽  
Dna Plasmid ◽  
2 Micron Plasmid ◽  
Acting In Concert

The yeast 2 micron plasmid achieves high fidelity segregation by coupling its partitioning pathway to that of the chromosomes. Mutations affecting distinct steps of chromosome segregation cause the plasmid to missegregate in tandem with the chromosomes. In the absence of the plasmid stability system, consisting of the Rep1 and Rep2 proteins and the STB DNA, plasmid and chromosome segregations are uncoupled. The Rep proteins, acting in concert, recruit the yeast cohesin complex to the STB locus. The periodicity of cohesin association and dissociation is nearly identical for the plasmid and the chromosomes. The timely disassembly of cohesin is a prerequisite for plasmid segregation. Cohesin-mediated pairing and unpairing likely provides a counting mechanism for evenly partitioning plasmids either in association with or independently of the chromosomes.

scholarly journals The role of bacteriocins as selfish genetic elements

2013 ◽  
Vol 9 (3) ◽  
pp. 20121173 ◽  
Author(s):  
R. Fredrik Inglis ◽  
Bihter Bayramoglu ◽  
Osnat Gillor ◽  
Martin Ackermann
Keyword(s):  
Plasmid Stability ◽  
Bacterial Strains ◽  
Genetic Elements ◽  
Selfish Genetic Elements ◽  
Daughter Cells ◽  
A Cell ◽  
Evolution Study ◽  
Stable Maintenance ◽  
Stable Transmission

Bacteria produce a wide arsenal of toxic compounds in order to kill competing species. Bacteriocins, protein-based toxins produced by nearly all bacteria, have generally been considered a ubiquitous anti-competitor strategy, used to kill competing bacterial strains. Some of these bacteriocins are encoded on plasmids, which also code for closely linked immunity compounds (thereby rendering toxin producing cells immune to their own toxin). However, the production of bacteriocins can also be interpreted as a means to promote plasmid stability by preferentially selecting for cells carrying the plasmid. If, for example, a cell were to lose the plasmid, it would no longer produce the immunity compound and would be killed by its bacteriocin-producing clone mates. In this respect, bacteriocins can be regarded as similar to previously described toxin–antitoxin systems that are able promote the stable transmission of plasmids to daughter cells. In order to test this prediction, we carried out an experimental evolution study using the bacterium Escherichia coli , finding that bacteriocins can indeed select for the stable maintenance of plasmids. This suggests that bacteriocins can act primarily as selfish genetic elements promoting their own transmission in the population, which may help explain their unique ecology and evolution.

scholarly journals Role of the parCBA Operon of the Broad-Host-Range Plasmid RK2 in Stable Plasmid Maintenance

1998 ◽  
Vol 180 (22) ◽  
pp. 6023-6030 ◽  
Author(s):  
Carla L. Easter ◽  
Helmut Schwab ◽  
Donald R. Helinski
Keyword(s):  
Host Range ◽  
Plasmid Stability ◽  
Broad Host Range ◽  
E Coli ◽  
Broad Host Range Plasmid ◽  
Resolution System ◽  
Stable Maintenance ◽  
Plasmid Stabilization ◽  
Plasmid Rk2

ABSTRACT The par region of the stably maintained broad-host-range plasmid RK2 is organized as two divergent operons,parCBA and parDE, and a cis-acting site. parDE encodes a postsegregational killing system, andparCBA encodes a resolvase (ParA), a nuclease (ParB), and a protein of unknown function (ParC). The present study was undertaken to further delineate the role of the parCBA region in the stable maintenance of RK2 by first introducing precise deletions in the three genes and then assessing the abilities of the different constructs to stabilize RK2 in three strains of Escherichia coli and two strains of Pseudomonas aeruginosa. The intact parCBA operon was effective in stabilizing a conjugation-defective RK2 derivative in E. coli MC1061K and RR1 but was relatively ineffective in E. coli MV10Δlac. In the two strains in which the parCBA operon was effective, deletions in parB, parC, or bothparB and parC caused an approximately twofold reduction in the stabilizing ability of the operon, while a deletion in the parA gene resulted in a much greater loss ofparCBA activity. For P. aeruginosaPAO1161Rifr, the parCBA operon provided little if any plasmid stability, but for P. aeruginosaPAC452Rifr, the RK2 plasmid was stabilized to a substantial extent by parCBA. With this latter strain, parAand res alone were sufficient for stabilization. Thecer resolvase system of plasmid ColE1 and theloxP/Cre system of plasmid P1 were tested in comparison with the parCBA operon. We found that, not unlike what was previously observed with MC1061K, cer failed to stabilize the RK2 plasmid with par deletions in strain MV10Δlac, but this multimer resolution system was effective in stabilizing the plasmid in strain RR1. The loxP/Cre system, on the other hand, was very effective in stabilizing the plasmid in all threeE. coli strains. These observations indicate that theparA gene, along with its res site, exhibits a significant level of plasmid stabilization in the absence of theparC and parB genes but that in at least oneE. coli strain, all three genes are required for maximum stabilization. It cannot be determined from these results whether or not the stabilization effects seen with parCBA or thecer and loxP/Cre systems are strictly due to a reduction in the level of RK2 dimers and an increase in the number of plasmid monomer units or if these systems play a role in a more complex process of plasmid stabilization that requires as an essential step the resolution of plasmid dimers.

Stable maintenance in chemostat-grown Escherichia coli of pBR322 and pACYC184 by disruption of the tetracycline resistance gene*

1985 ◽  
Vol 5 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Thierry Vernet ◽  
Ian J. McDonald ◽  
Dave R. Cameron ◽  
Louis P. Visentin
Keyword(s):  
Escherichia Coli ◽  
Resistance Gene ◽  
Plasmid Stability ◽  
Tetracycline Resistance ◽  
Cloning Vector ◽  
Tetracycline Resistance Gene ◽  
Plasmid Maintenance ◽  
Stable Maintenance ◽  
Vector Pbr322

Plasmid stability was studied in antibiotic-free chemo-stat cultures. Disruption, either by deletion or insertion, of the tetracycline resistance gene in the EcoRl/EcoRV region of the cloning vector pBR322 or in the HindIII]BamHl region of pACYCI84 yields plasmids markedly more stable than the parent plasmids. Thus, at least for these two instances, cloning of a partitioning (par) locus is not prerequisite for plasmid maintenance.

scholarly journals A natural variant of the essential host gene MMS21 restricts the parasitic 2-micron plasmid in Saccharomyces cerevisiae

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Michelle Hays ◽  
Janet M Young ◽  
Paula F Levan ◽  
Harmit S Malik
Keyword(s):  
Chromosome Segregation ◽  
Natural Variation ◽  
Plasmid Stability ◽  
Live Cells ◽  
Selfish Genetic Elements ◽  
Plasmid Loss ◽  
Chromatid Cohesion ◽  
Natural Variant ◽  
Trait Locus ◽  
2 Micron Plasmid

Antagonistic coevolution with selfish genetic elements (SGEs) can drive evolution of host resistance. Here, we investigated host suppression of 2-micron (2μ) plasmids, multicopy nuclear parasites that have co-evolved with budding yeasts. We developed SCAMPR (Single-Cell Assay for Measuring Plasmid Retention) to measure copy number heterogeneity and 2μ plasmid loss in live cells. We identified three S. cerevisiae strains that lack endogenous 2μ plasmids and reproducibly inhibit mitotic plasmid stability. Focusing on the Y9 ragi strain, we determined that plasmid restriction is heritable and dominant. Using bulk segregant analysis, we identified a high-confidence Quantitative Trait Locus (QTL) with a single variant of MMS21 associated with increased 2μ instability. MMS21 encodes a SUMO E3 ligase and an essential component of the Smc5/6 complex, involved in sister chromatid cohesion, chromosome segregation, and DNA repair. Our analyses leverage natural variation to uncover a novel means by which budding yeasts can overcome highly successful genetic parasites.

scholarly journals The selfish yeast plasmid uses the nuclear motor Kip1p but not Cin8p for its localization and equal segregation

2009 ◽  
Vol 185 (2) ◽  
pp. 251-264 ◽  
Author(s):  
Hong Cui ◽  
Santanu K. Ghosh ◽  
Makkuni Jayaram
Keyword(s):  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Reporter Plasmid ◽  
Yeast Plasmid ◽  
Pole Body ◽  
Close Proximity ◽  
Plasmid Partitioning ◽  
2 Micron Plasmid

The 2 micron plasmid of Saccharomyces cerevisiae uses the Kip1 motor, but not the functionally redundant Cin8 motor, for its precise nuclear localization and equal segregation. The timing and lifetime of Kip1p association with the plasmid partitioning locus STB are consistent with Kip1p being an authentic component of the plasmid partitioning complex. Kip1–STB association is not blocked by disassembling the mitotic spindle. Lack of Kip1p disrupts recruitment of the cohesin complex at STB and cohesion of replicated plasmid molecules. Colocalization of a 2 micron reporter plasmid with Kip1p in close proximity to the spindle pole body is reminiscent of that of a CEN reporter plasmid. Absence of Kip1p displaces the plasmid from this nuclear address, where it has the potential to tether to a chromosome or poach chromosome segregation factors. Exploiting Kip1p, which is subsidiary to Cin8p for chromosome segregation, to direct itself to a “partitioning center” represents yet another facet of the benign parasitism of the yeast plasmid.

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