Nuclear Plasmids of Dictyostelium

Hughes, Judith M.; Welker, Dennis L.

doi:10.1007/978-1-4615-4707-5_1

Cited by 2 publications

(2 citation statements)

References 69 publications

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“…Eukaryotes, in contrast to prokaryotes, rarely harbor stably propagating extra-chromosomal DNA elements. However, circular plasmids have been identified in budding yeasts and in the slime mold Dictyostelium [1,2]. In addition, papilloma and gammaherpes viruses exist as episomes in infected mammalian cells during long periods of latency [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…Circular DNA plasmids, widespread among prokaryotes, are almost nonexistent among eukaryotes. Certain members of the budding yeast and Dictyostelium species present a rare exception by harboring circular plasmids in their nuclei ( 1 , 2 ). Furthermore, viruses belonging to the papilloma family and gammaherpes sub-family are propagated as episomes in infected cells during long periods of latency ( 3 – 6 ).…”

Section: Introductionmentioning

confidence: 99%

Replication-dependent and independent mechanisms for the chromosome-coupled persistence of a selfish genome

Liu

Chang

et al. 2016

Nucleic Acids Res

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The yeast 2-micron plasmid epitomizes the evolutionary optimization of selfish extra-chromosomal genomes for stable persistence without jeopardizing their hosts’ fitness. Analyses of fluorescence-tagged single-copy reporter plasmids and/or the plasmid partitioning proteins in native and non-native hosts reveal chromosome-hitchhiking as the likely means for plasmid segregation. The contribution of the partitioning system to equal segregation is bipartite- replication-independent and replication-dependent. The former nearly eliminates ‘mother bias’ (preferential plasmid retention in the mother cell) according to binomial distribution, thus limiting equal segregation of a plasmid pair to 50%. The latter enhances equal segregation of plasmid sisters beyond this level, elevating the plasmid close to chromosome status. Host factors involved in plasmid partitioning can be functionally separated by their participation in the replication-independent and/or replication-dependent steps. In the hitchhiking model, random tethering of a pair of plasmids to chromosomes signifies the replication-independent component of segregation; the symmetric tethering of plasmid sisters to sister chromatids embodies the replication-dependent component. The 2-micron circle broadly resembles the episomes of certain mammalian viruses in its chromosome-associated propagation. This unifying feature among otherwise widely differing selfish genomes suggests their evolutionary convergence to the common logic of exploiting, albeit via distinct molecular mechanisms, host chromosome segregation machineries for self-preservation.

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Nuclear Plasmids of Dictyostelium

Cited by 2 publications

References 69 publications

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

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

Replication-dependent and independent mechanisms for the chromosome-coupled persistence of a selfish genome

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