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Hays M. Genetic conflicts in budding yeast: The 2μ plasmid as a model selfish element. Semin Cell Dev Biol 2024; 161-162:31-41. [PMID: 38598944 DOI: 10.1016/j.semcdb.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/12/2024]
Abstract
Antagonistic coevolution, arising from genetic conflict, can drive rapid evolution and biological innovation. Conflict can arise both between organisms and within genomes. This review focuses on budding yeasts as a model system for exploring intra- and inter-genomic genetic conflict, highlighting in particular the 2-micron (2μ) plasmid as a model selfish element. The 2μ is found widely in laboratory strains and industrial isolates of Saccharomyces cerevisiae and has long been known to cause host fitness defects. Nevertheless, the plasmid is frequently ignored in the context of genetic, fitness, and evolution studies. Here, I make a case for further exploring the evolutionary impact of the 2μ plasmid as well as other selfish elements of budding yeasts, discuss recent advances, and, finally, future directions for the field.
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Affiliation(s)
- Michelle Hays
- Department of Genetics, Stanford University, Stanford, CA, United States.
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2
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Ma CH, Kumar D, Jayaram M, Ghosh SK, Iyer VR. The selfish yeast plasmid exploits a SWI/SNF-type chromatin remodeling complex for hitchhiking on chromosomes and ensuring high-fidelity propagation. PLoS Genet 2023; 19:e1010986. [PMID: 37812641 PMCID: PMC10586699 DOI: 10.1371/journal.pgen.1010986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 10/19/2023] [Accepted: 09/19/2023] [Indexed: 10/11/2023] Open
Abstract
Extra-chromosomal selfish DNA elements can evade the risk of being lost at every generation by behaving as chromosome appendages, thereby ensuring high fidelity segregation and stable persistence in host cell populations. The yeast 2-micron plasmid and episomes of the mammalian gammaherpes and papilloma viruses that tether to chromosomes and segregate by hitchhiking on them exemplify this strategy. We document for the first time the utilization of a SWI/SNF-type chromatin remodeling complex as a conduit for chromosome association by a selfish element. One principal mechanism for chromosome tethering by the 2-micron plasmid is the bridging interaction of the plasmid partitioning proteins (Rep1 and Rep2) with the yeast RSC2 complex and the plasmid partitioning locus STB. We substantiate this model by multiple lines of evidence derived from genomics, cell biology and interaction analyses. We describe a Rep-STB bypass system in which a plasmid engineered to non-covalently associate with the RSC complex mimics segregation by chromosome hitchhiking. Given the ubiquitous prevalence of SWI/SNF family chromatin remodeling complexes among eukaryotes, it is likely that the 2-micron plasmid paradigm or analogous ones will be encountered among other eukaryotic selfish elements.
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Affiliation(s)
- Chien-Hui Ma
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Deepanshu Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Makkuni Jayaram
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Santanu K. Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Vishwanath R. Iyer
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
- Livestrong Cancer Institutes and Department of Oncology, Dell Medical School, The University of Texas at Austin, Austin, Texas, United States of America
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3
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Mereshchuk A, Johnstone PS, Chew JSK, Dobson MJ. The yeast 2-micron plasmid Rep2 protein has Rep1-independent partitioning function. Nucleic Acids Res 2022; 50:10571-10585. [PMID: 36156142 PMCID: PMC9561267 DOI: 10.1093/nar/gkac810] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 08/18/2022] [Accepted: 09/08/2022] [Indexed: 11/13/2022] Open
Abstract
Equal partitioning of the multi-copy 2-micron plasmid of the budding yeast Saccharomyces cerevisiae requires association of the plasmid Rep1 and Rep2 proteins with the plasmid STB partitioning locus. Determining how the Rep proteins contribute has been complicated by interactions between the components. Here, each Rep protein was expressed fused to the DNA-binding domain of the bacterial repressor protein LexA in yeast harboring a replication-competent plasmid that had LexA-binding sites but lacked STB. Plasmid transmission to daughter cells was increased only by Rep2 fusion expression. Neither Rep1 nor a functional RSC2 complex (a chromatin remodeler required for 2-micron plasmid partitioning) were needed for the improvement. Deletion analysis showed the carboxy-terminal 65 residues of Rep2 were required and sufficient for this Rep1-independent inheritance. Mutation of a conserved basic motif in this domain impaired Rep1-independent and Rep protein/STB-dependent plasmid partitioning. Our findings suggest Rep2, which requires Rep1 and the RSC2 complex for functional association with STB, directly participates in 2-micron plasmid partitioning by linking the plasmid to a host component that is efficiently partitioned during cell division. Further investigation is needed to reveal the host factor targeted by Rep2 that contributes to the survival of these plasmids in their budding yeast hosts.
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Affiliation(s)
- Anastasiia Mereshchuk
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Peter S Johnstone
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Joyce S K Chew
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Melanie J Dobson
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
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4
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The selfish yeast plasmid utilizes the condensin complex and condensed chromatin for faithful partitioning. PLoS Genet 2021; 17:e1009660. [PMID: 34270553 PMCID: PMC8318298 DOI: 10.1371/journal.pgen.1009660] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 07/28/2021] [Accepted: 06/10/2021] [Indexed: 11/19/2022] Open
Abstract
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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5
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Hays M, Young JM, Levan PF, Malik HS. A natural variant of the essential host gene MMS21 restricts the parasitic 2-micron plasmid in Saccharomyces cerevisiae. eLife 2020; 9:62337. [PMID: 33063663 PMCID: PMC7652418 DOI: 10.7554/elife.62337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 10/15/2020] [Indexed: 12/30/2022] Open
Abstract
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.
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Affiliation(s)
- Michelle Hays
- Molecular and Cellular Biology program, University of Washington, Seattle, United States.,Division of Basic Sciences & Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Janet M Young
- Division of Basic Sciences & Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Paula F Levan
- Division of Basic Sciences & Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Harmit S Malik
- Division of Basic Sciences & Fred Hutchinson Cancer Research Center, Seattle, United States.,Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, United States
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George J, Kahlke T, Abbriano RM, Kuzhiumparambil U, Ralph PJ, Fabris M. Metabolic Engineering Strategies in Diatoms Reveal Unique Phenotypes and Genetic Configurations With Implications for Algal Genetics and Synthetic Biology. Front Bioeng Biotechnol 2020; 8:513. [PMID: 32582656 PMCID: PMC7290003 DOI: 10.3389/fbioe.2020.00513] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 04/30/2020] [Indexed: 12/23/2022] Open
Abstract
Diatoms are photosynthetic microeukaryotes that dominate phytoplankton populations and have increasing applicability in biotechnology. Uncovering their complex biology and elevating strains to commercial standards depends heavily on robust genetic engineering tools. However, engineering microalgal genomes predominantly relies on random integration of transgenes into nuclear DNA, often resulting in detrimental “position-effects” such as transgene silencing, integration into transcriptionally-inactive regions, and endogenous sequence disruption. With the recent development of extrachromosomal transgene expression via independent episomes, it is timely to investigate both strategies at the phenotypic and genomic level. Here, we engineered the model diatom Phaeodactylum tricornutum to produce the high-value heterologous monoterpenoid geraniol, which, besides applications as fragrance and insect repellent, is a key intermediate of high-value pharmaceuticals. Using high-throughput phenotyping we confirmed the suitability of episomes for synthetic biology applications and identified superior geraniol-yielding strains following random integration. We used third generation long-read sequencing technology to generate a complete analysis of all transgene integration events including their genomic locations and arrangements associated with high-performing strains at a genome-wide scale with subchromosomal detail, never before reported in any microalga. This revealed very large, highly concatenated insertion islands, offering profound implications on diatom functional genetics and next generation genome editing technologies, and is key for developing more precise genome engineering approaches in diatoms, including possible genomic safe harbour locations to support high transgene expression for targeted integration approaches. Furthermore, we have demonstrated that exogenous DNA is not integrated inadvertently into the nuclear genome of extrachromosomal-expression clones, an important characterisation of this novel engineering approach that paves the road to synthetic biology applications.
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Affiliation(s)
- Jestin George
- University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, NSW, Australia
| | - Tim Kahlke
- University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, NSW, Australia
| | - Raffaela M Abbriano
- University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, NSW, Australia
| | | | - Peter J Ralph
- University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, NSW, Australia
| | - Michele Fabris
- University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, NSW, Australia.,CSIRO Synthetic Biology Future Science Platform, Brisbane, QLD, Australia
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McQuaid ME, Polvi EJ, Dobson MJ. DNA sequence elements required for partitioning competence of the Saccharomyces cerevisiae 2-micron plasmid STB locus. Nucleic Acids Res 2019; 47:716-728. [PMID: 30445476 PMCID: PMC6344848 DOI: 10.1093/nar/gky1150] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 10/29/2018] [Indexed: 11/17/2022] Open
Abstract
Equal partitioning of the multi-copy yeast 2-micron plasmid requires association of plasmid proteins Rep1 and Rep2 with tandem repeats at the plasmid STB locus. To identify sequence elements required for these associations we generated synthetic versions of a 63-bp section of STB, encompassing one repeat. A single copy of this sequence was sufficient for Rep protein association in vivo, while two directly arrayed copies provided partitioning function to a plasmid lacking all other 2-micron sequences. Partitioning efficiency increased with increasing repeat number, reaching that conferred by the native STB repeat array. By altering sequences in synthetic repeats, we identified the TGCA component of a TGCATTTTT motif as critical for Rep protein recognition, with a second TGCA sequence in each repeat also contributing to association. Mutation of TGCATTTTT to TGTATTTT, as found in variant 2-micron STB repeats, also allowed Rep protein association, while mutation to TGCATTAAT impaired inheritance without abolishing Rep protein recognition, suggesting an alternate role for the T-tract. Our identification of sequence motifs required for Rep protein recognition provides the basis for understanding higher-order Rep protein arrangements at STB that enable the yeast 2-micron plasmid to be efficiently partitioned during host cell division.
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Affiliation(s)
- Mary E McQuaid
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Elizabeth J Polvi
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Melanie J Dobson
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Ma CH, Su BY, Maciaszek A, Fan HF, Guga P, Jayaram M. A Flp-SUMO hybrid recombinase reveals multi-layered copy number control of a selfish DNA element through post-translational modification. PLoS Genet 2019; 15:e1008193. [PMID: 31242181 PMCID: PMC6594588 DOI: 10.1371/journal.pgen.1008193] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 05/13/2019] [Indexed: 12/30/2022] Open
Abstract
Mechanisms for highly efficient chromosome-associated equal segregation, and for maintenance of steady state copy number, are at the heart of the evolutionary success of the 2-micron plasmid as a stable multi-copy extra-chromosomal selfish DNA element present in the yeast nucleus. The Flp site-specific recombination system housed by the plasmid, which is central to plasmid copy number maintenance, is regulated at multiple levels. Transcription of the FLP gene is fine-tuned by the repressor function of the plasmid-coded partitioning proteins Rep1 and Rep2 and their antagonist Raf1, which is also plasmid-coded. In addition, the Flp protein is regulated by the host's post-translational modification machinery. Utilizing a Flp-SUMO fusion protein, which functionally mimics naturally sumoylated Flp, we demonstrate that the modification signals ubiquitination of Flp, followed by its proteasome-mediated degradation. Furthermore, reduced binding affinity and cooperativity of the modified Flp decrease its association with the plasmid FRT (Flp recombination target) sites, and/or increase its dissociation from them. The resulting attenuation of strand cleavage and recombination events safeguards against runaway increase in plasmid copy number, which is deleterious to the host-and indirectly-to the plasmid. These results have broader relevance to potential mechanisms by which selfish genomes minimize fitness conflicts with host genomes by holding in check the extra genetic load they pose.
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Affiliation(s)
- Chien-Hui Ma
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States of America
| | - Bo-Yu Su
- Department of Life Sciences and Institute of Genome Sciences, Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, Taipei City, Taiwan
| | - Anna Maciaszek
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Department of Bioorganic Chemistry, Lodz, Poland
| | - Hsiu-Fang Fan
- Department of Life Sciences and Institute of Genome Sciences, Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, Taipei City, Taiwan
| | - Piotr Guga
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Department of Bioorganic Chemistry, Lodz, Poland
| | - Makkuni Jayaram
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States of America
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9
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Insights into the DNA sequence elements required for partitioning and copy number control of the yeast 2-micron plasmid. Curr Genet 2019; 65:887-892. [PMID: 30915516 DOI: 10.1007/s00294-019-00958-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 03/15/2019] [Accepted: 03/16/2019] [Indexed: 10/27/2022]
Abstract
The yeast 2-micron plasmid is an almost perfect selfish DNA. The entire coding capacity of the plasmid is dedicated to ensuring its own inheritance, with no benefit to its host. Despite high copy number, the plasmid confers no phenotype. It manages this feat by possessing mechanisms for plasmid copy-number control and for partitioning. The former increases plasmid numbers when they fall, but is repressed at high copy number, while the latter ensures 2-micron copies are equally partitioned during host cell division. Although the plasmid amplification mechanism is well established, the partitioning system and the means by which the 2-micron plasmid partitioning proteins, Rep1 and Rep2, regulate plasmid copy number remain incompletely understood. This review focuses on recent efforts to determine the nature of Rep protein complexes formed at the plasmid stability locus (STB) and at plasmid gene promoters, the identity of DNA sequence elements required for Rep protein association, and the mechanism by which the Rep proteins manage their dual roles of plasmid partitioning and plasmid gene repression.
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10
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Sau S, Ghosh SK, Liu YT, Ma CH, Jayaram M. Hitchhiking on chromosomes: A persistence strategy shared by diverse selfish DNA elements. Plasmid 2019; 102:19-28. [PMID: 30726706 DOI: 10.1016/j.plasmid.2019.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/29/2019] [Accepted: 01/31/2019] [Indexed: 12/12/2022]
Abstract
An underlying theme in the segregation of low-copy bacterial plasmids is the assembly of a 'segrosome' by DNA-protein and protein-protein interactions, followed by energy-driven directed movement. Analogous partitioning mechanisms drive the segregation of host chromosomes as well. Eukaryotic extra-chromosomal elements, exemplified by budding yeast plasmids and episomes of certain mammalian viruses, harbor partitioning systems that promote their physical association with chromosomes. In doing so, they indirectly take advantage of the spindle force that directs chromosome movement to opposite cell poles. Molecular-genetic, biochemical and cell biological studies have revealed several unsuspected aspects of 'chromosome hitchhiking' by the yeast 2-micron plasmid, including the ability of plasmid sisters to associate symmetrically with sister chromatids. As a result, the plasmid overcomes the 'mother bias' experienced by plasmids lacking a partitioning system, and elevates itself to near chromosome status in equal segregation. Chromosome association for stable propagation, without direct energy expenditure, may also be utilized by a small minority of bacterial plasmids-at least one case has been reported. Given the near perfect accuracy of chromosome segregation, it is not surprising that elements residing in evolutionarily distant host organisms have converged upon the common strategy of gaining passage to daughter cells as passengers on chromosomes.
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Affiliation(s)
- Soumitra Sau
- Amity Institute of Biotechnology, Amity University Kolkata, Kolkata 700135, India
| | - Santanu Kumar Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Yen-Ting Liu
- Department of Molecular Biosciences, UT Austin, Austin, TX TX7 8712, USA
| | - Chien-Hui Ma
- Department of Molecular Biosciences, UT Austin, Austin, TX TX7 8712, USA
| | - Makkuni Jayaram
- Department of Molecular Biosciences, UT Austin, Austin, TX TX7 8712, USA.
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A Rizvi SM, Prajapati HK, Nag P, Ghosh SK. The 2-μm plasmid encoded protein Raf1 regulates both stability and copy number of the plasmid by blocking the formation of the Rep1-Rep2 repressor complex. Nucleic Acids Res 2017; 45:7167-7179. [PMID: 28472368 PMCID: PMC5499539 DOI: 10.1093/nar/gkx316] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 04/14/2017] [Indexed: 12/02/2022] Open
Abstract
The 2-μm plasmid of the budding yeast Saccharomyces cerevisiae achieves a high chromosome-like stability with the help of four plasmid-encoded (Rep1, Rep2, Raf1 and Flp) and several host-encoded proteins. Rep1 and Rep2 and the DNA locus STB form the partitioning system ensuring equal segregation of the plasmid. The Flp recombinase and its target sites FRTs form the amplification system which is responsible for the steady state plasmid copy number. In this work we show that the absence of Raf1 can affect both the plasmid stability and the steady sate copy number. We also show that the Rep proteins do bind to the promoter regions of the 2-μm encoded genes, as predicted by earlier models and Raf1 indeed blocks the formation of the Rep1–Rep2 repressor complex not by blocking the transcription of the REP1 and REP2 genes but by physically associating with the Rep proteins and negating their interactions. This explains the role of Raf1 in both the partitioning and the amplification systems as the Rep1–Rep2 complex is believed to modulate both these systems. Based on this study, we have provided, from a systems biology perspective, a model for the mechanism of the 2-μm plasmid maintenance.
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Affiliation(s)
- Syed M A Rizvi
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, Maharashtra, India
| | - Hemant K Prajapati
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, Maharashtra, India
| | - Purba Nag
- Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane Queensland 4006, Australia
| | - Santanu K Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, Maharashtra, India
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12
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Cao M, Gao M, Lopez-Garcia CL, Wu Y, Seetharam AS, Severin AJ, Shao Z. Centromeric DNA Facilitates Nonconventional Yeast Genetic Engineering. ACS Synth Biol 2017; 6:1545-1553. [PMID: 28391682 DOI: 10.1021/acssynbio.7b00046] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Many nonconventional yeast species have highly desirable features that are not possessed by model yeasts, despite that significant technology hurdles to effectively manipulate them lay in front. Scheffersomyces stipitis is one of the most important exemplary nonconventional yeasts in biorenewables industry, which has a high native xylose utilization capacity. Recent study suggested its much better potential than Saccharomyces cerevisiae as a well-suited microbial biomanufacturing platform for producing high-value compounds derived from shikimate pathway, many of which are associated with potent nutraceutical or pharmaceutical properties. However, the broad application of S. stipitis is hampered by the lack of stable episomal expression platforms and precise genome-editing tools. Here we report the success in pinpointing the centromeric DNA as the partitioning element to guarantee stable extra-chromosomal DNA segregation. The identified centromeric sequence not only stabilized episomal plasmid, enabled homogeneous gene expression, increased the titer of a commercially relevant compound by 3-fold, and also dramatically increased gene knockout efficiency from <1% to more than 80% with the expression of CRISPR components on the new stable plasmid. This study elucidated that establishment of a stable minichromosome-like expression platform is key to achieving functional modifications of nonconventional yeast species in order to expand the current collection of microbial factories.
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Affiliation(s)
- Mingfeng Cao
- Department
of Chemical and Biological Engineering, ‡NSF Engineering Research Center
for Biorenewable Chemicals (CBiRC), §Genome Informatics Facility, Office of Biotechnology, ∥Interdepartmental
Microbiology Program, and ⊥The Ames Laboratory, Iowa State University, 4140 Biorenewables Research Laboratory, Ames, Iowa 50011, United States
| | - Meirong Gao
- Department
of Chemical and Biological Engineering, ‡NSF Engineering Research Center
for Biorenewable Chemicals (CBiRC), §Genome Informatics Facility, Office of Biotechnology, ∥Interdepartmental
Microbiology Program, and ⊥The Ames Laboratory, Iowa State University, 4140 Biorenewables Research Laboratory, Ames, Iowa 50011, United States
| | - Carmen Lorena Lopez-Garcia
- Department
of Chemical and Biological Engineering, ‡NSF Engineering Research Center
for Biorenewable Chemicals (CBiRC), §Genome Informatics Facility, Office of Biotechnology, ∥Interdepartmental
Microbiology Program, and ⊥The Ames Laboratory, Iowa State University, 4140 Biorenewables Research Laboratory, Ames, Iowa 50011, United States
| | - Yutong Wu
- Department
of Chemical and Biological Engineering, ‡NSF Engineering Research Center
for Biorenewable Chemicals (CBiRC), §Genome Informatics Facility, Office of Biotechnology, ∥Interdepartmental
Microbiology Program, and ⊥The Ames Laboratory, Iowa State University, 4140 Biorenewables Research Laboratory, Ames, Iowa 50011, United States
| | - Arun Somwarpet Seetharam
- Department
of Chemical and Biological Engineering, ‡NSF Engineering Research Center
for Biorenewable Chemicals (CBiRC), §Genome Informatics Facility, Office of Biotechnology, ∥Interdepartmental
Microbiology Program, and ⊥The Ames Laboratory, Iowa State University, 4140 Biorenewables Research Laboratory, Ames, Iowa 50011, United States
| | - Andrew Josef Severin
- Department
of Chemical and Biological Engineering, ‡NSF Engineering Research Center
for Biorenewable Chemicals (CBiRC), §Genome Informatics Facility, Office of Biotechnology, ∥Interdepartmental
Microbiology Program, and ⊥The Ames Laboratory, Iowa State University, 4140 Biorenewables Research Laboratory, Ames, Iowa 50011, United States
| | - Zengyi Shao
- Department
of Chemical and Biological Engineering, ‡NSF Engineering Research Center
for Biorenewable Chemicals (CBiRC), §Genome Informatics Facility, Office of Biotechnology, ∥Interdepartmental
Microbiology Program, and ⊥The Ames Laboratory, Iowa State University, 4140 Biorenewables Research Laboratory, Ames, Iowa 50011, United States
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13
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Rizvi SMA, Prajapati HK, Ghosh SK. The 2 micron plasmid: a selfish genetic element with an optimized survival strategy within Saccharomyces cerevisiae. Curr Genet 2017; 64:25-42. [PMID: 28597305 DOI: 10.1007/s00294-017-0719-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 05/29/2017] [Accepted: 05/30/2017] [Indexed: 11/27/2022]
Abstract
Since its discovery in the early 70s, the 2 micron plasmid of Saccharomyces cerevisiae continues to intrigue researchers with its high protein-coding capacity and a selfish nature yet high stability, earning it the title of a 'miniaturized selfish genetic element'. It codes for four proteins (Rep1, Rep2, Raf1, and Flp) vital for its own survival and recruits several host factors (RSC2, Cohesin, Cse4, Kip1, Bik1, Bim1, and microtubules) for its faithful segregation during cell division. The plasmid maintains a high-copy number with the help of Flp-mediated recombination. The plasmids organize in the form of clusters that hitch-hike the host chromosomes presumably with the help of the plasmid-encoded Rep proteins and host factors such as microtubules, Kip1 motor, and microtubule-associated proteins Bik1 and Bim1. Although there is no known yeast cell phenotype associated with the 2 micron plasmid, excessive copies of the plasmid are lethal for the cells, warranting a tight control over the plasmid copy number. This control is achieved through a combination of feedback loops involving the 2 micron encoded proteins. Thus, faithful segregation and a concomitant tightly controlled plasmid copy number ensure an optimized benign parasitism of the 2 micron plasmid within budding yeast.
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Affiliation(s)
- Syed Meraj Azhar Rizvi
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076, India
| | - Hemant Kumar Prajapati
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076, India
| | - Santanu Kumar Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076, India.
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14
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Rowley PA. The frenemies within: viruses, retrotransposons and plasmids that naturally infect Saccharomyces yeasts. Yeast 2017; 34:279-292. [PMID: 28387035 DOI: 10.1002/yea.3234] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 11/07/2022] Open
Abstract
Viruses are a major focus of current research efforts because of their detrimental impact on humanity and their ubiquity within the environment. Bacteriophages have long been used to study host-virus interactions within microbes, but it is often forgotten that the single-celled eukaryote Saccharomyces cerevisiae and related species are infected with double-stranded RNA viruses, single-stranded RNA viruses, LTR-retrotransposons and double-stranded DNA plasmids. These intracellular nucleic acid elements have some similarities to higher eukaryotic viruses, i.e. yeast retrotransposons have an analogous lifecycle to retroviruses, the particle structure of yeast totiviruses resembles the capsid of reoviruses and segregation of yeast plasmids is analogous to segregation strategies used by viral episomes. The powerful experimental tools available to study the genetics, cell biology and evolution of S. cerevisiae are well suited to further our understanding of how cellular processes are hijacked by eukaryotic viruses, retrotransposons and plasmids. This article has been written to briefly introduce viruses, retrotransposons and plasmids that infect Saccharomyces yeasts, emphasize some important cellular proteins and machineries with which they interact, and suggest the evolutionary consequences of these interactions. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Paul A Rowley
- Department of Biological Sciences, The University of Idaho, Moscow, Idaho, USA
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15
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Prajapati HK, Rizvi SMA, Rathore I, Ghosh SK. Microtubule-associated proteins, Bik1 and Bim1, are required for faithful partitioning of the endogenous 2 micron plasmids in budding yeast. Mol Microbiol 2017; 103:1046-1064. [PMID: 28004422 DOI: 10.1111/mmi.13608] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2016] [Indexed: 12/01/2022]
Abstract
The 2 μ plasmid of budding yeast shows high mitotic stability similar to that of chromosomes by using its self-encoded systems, namely partitioning and amplification. The partitioning system consists of the plasmid-borne proteins Rep1, Rep2 and a cis-acting locus STB that, along with several host factors, ensures efficient segregation of the plasmid. The plasmids show high stability as they presumably co-segregate with chromosomes through utilization of various host factors. To acquire these host factors, the plasmids are thought to localize to a certain sub-nuclear locale probably assisted by the motor protein, Kip1 and microtubules. Here, we show that the microtubule-associated proteins Bik1 and Bim1 are also important host factors in this process, perhaps by acting as an adapter between the plasmid and the motor and thus helping to anchor the plasmid to microtubules. Abrogation of Kip1 recruitment at STB in the absence of Bik1 argues for its function at STB upstream of Kip1. Consistent with this, both Bik1 and Bim1 associate with plasmids without any assistance from the Rep proteins. As observed earlier with other host factors, lack of Bik1 or Bim1 also causes a cohesion defect between sister plasmids leading to plasmid missegregation.
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Affiliation(s)
- Hemant Kumar Prajapati
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076, India
| | - Syed Meraj Azhar Rizvi
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076, India
| | - Ishan Rathore
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076, India
| | - Santanu K Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076, India
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16
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Liu YT, Chang KM, Ma CH, Jayaram M. Replication-dependent and independent mechanisms for the chromosome-coupled persistence of a selfish genome. Nucleic Acids Res 2016; 44:8302-23. [PMID: 27492289 PMCID: PMC5041486 DOI: 10.1093/nar/gkw694] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 07/26/2016] [Accepted: 07/27/2016] [Indexed: 12/21/2022] Open
Abstract
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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Affiliation(s)
- Yen-Ting Liu
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Keng-Ming Chang
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Chien-Hui Ma
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Makkuni Jayaram
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
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17
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Tsabar M, Haase J, Harrison B, Snider CE, Eldridge B, Kaminsky L, Hine RM, Haber JE, Bloom K. A Cohesin-Based Partitioning Mechanism Revealed upon Transcriptional Inactivation of Centromere. PLoS Genet 2016; 12:e1006021. [PMID: 27128635 PMCID: PMC4851351 DOI: 10.1371/journal.pgen.1006021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 04/08/2016] [Indexed: 12/24/2022] Open
Abstract
Transcriptional inactivation of the budding yeast centromere has been a widely used tool in studies of chromosome segregation and aneuploidy. In haploid cells when an essential chromosome contains a single conditionally inactivated centromere (GAL-CEN), cell growth rate is slowed and segregation fidelity is reduced; but colony formation is nearly 100%. Pedigree analysis revealed that only 30% of the time both mother and daughter cell inherit the GAL-CEN chromosome. The reduced segregation capacity of the GAL-CEN chromosome is further compromised upon reduction of pericentric cohesin (mcm21∆), as reflected in a further diminishment of the Mif2 kinetochore protein at GAL-CEN. By redistributing cohesin from the nucleolus to the pericentromere (by deleting SIR2), there is increased presence of the kinetochore protein Mif2 at GAL-CEN and restoration of cell viability. These studies identify the ability of cohesin to promote chromosome segregation via kinetochore assembly, in a situation where the centromere has been severely compromised.
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Affiliation(s)
- Michael Tsabar
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - Julian Haase
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Benjamin Harrison
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Chloe E. Snider
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Brittany Eldridge
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Lila Kaminsky
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - Rebecca M. Hine
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - James E. Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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18
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The partitioning and copy number control systems of the selfish yeast plasmid: an optimized molecular design for stable persistence in host cells. Microbiol Spectr 2016; 2. [PMID: 25541598 DOI: 10.1128/microbiolspec.plas-0003-2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The multi-copy 2 micron plasmid of Saccharomyces cerevisiae, a resident of the nucleus, is remarkable for its high chromosome-like stability. The plasmid does not appear to contribute to the fitness of the host, nor does it impose a significant metabolic burden on the host at its steady state copy number. The plasmid may be viewed as a highly optimized selfish DNA element whose genome design is devoted entirely towards efficient replication, equal segregation and copy number maintenance. A partitioning system comprised of two plasmid coded proteins, Rep1 and Rep2, and a partitioning locus STB is responsible for equal or nearly equal segregation of plasmid molecules to mother and daughter cells. Current evidence supports a model in which the Rep-STB system promotes the physical association of the plasmid with chromosomes and thus plasmid segregation by a hitchhiking mechanism. The Flp site-specific recombination system housed by the plasmid plays a critical role in maintaining steady state plasmid copy number. A decrease in plasmid population due to rare missegregation events is rectified by plasmid amplification via a recombination induced rolling circle replication mechanism. Appropriate plasmid amplification, without runaway increase in copy number, is ensured by positive and negative regulation of FLP gene expression by plasmid coded proteins and by the control of Flp level/activity through host mediated post-translational modification(s) of Flp. The Flp system has been successfully utilized to understand mechanisms of site-specific recombination, to bring about directed genetic alterations for addressing fundamental problems in biology, and as a tool in biotechnological applications.
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19
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Campbell K, Vowinckel J, Mülleder M, Malmsheimer S, Lawrence N, Calvani E, Miller-Fleming L, Alam MT, Christen S, Keller MA, Ralser M. Self-establishing communities enable cooperative metabolite exchange in a eukaryote. eLife 2015; 4:e09943. [PMID: 26499891 PMCID: PMC4695387 DOI: 10.7554/elife.09943] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/20/2015] [Indexed: 11/13/2022] Open
Abstract
Metabolite exchange among co-growing cells is frequent by nature, however, is not necessarily occurring at growth-relevant quantities indicative of non-cell-autonomous metabolic function. Complementary auxotrophs of Saccharomyces cerevisiae amino acid and nucleotide metabolism regularly fail to compensate for each other's deficiencies upon co-culturing, a situation which implied the absence of growth-relevant metabolite exchange interactions. Contrastingly, we find that yeast colonies maintain a rich exometabolome and that cells prefer the uptake of extracellular metabolites over self-synthesis, indicators of ongoing metabolite exchange. We conceived a system that circumvents co-culturing and begins with a self-supporting cell that grows autonomously into a heterogeneous community, only able to survive by exchanging histidine, leucine, uracil, and methionine. Compensating for the progressive loss of prototrophy, self-establishing communities successfully obtained an auxotrophic composition in a nutrition-dependent manner, maintaining a wild-type like exometabolome, growth parameters, and cell viability. Yeast, as a eukaryotic model, thus possesses extensive capacity for growth-relevant metabolite exchange and readily cooperates in metabolism within progressively establishing communities.
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Affiliation(s)
- Kate Campbell
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
| | - Jakob Vowinckel
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
| | - Michael Mülleder
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
| | - Silke Malmsheimer
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
| | - Nicola Lawrence
- The Wellcome Trust Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
| | - Enrica Calvani
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
| | - Leonor Miller-Fleming
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
| | - Mohammad T Alam
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
| | - Stefan Christen
- Institute of Molecular Systems Biology, ETH Zürich, Zurich, Switzerland
| | - Markus A Keller
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
| | - Markus Ralser
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
- Mill Hill Laboratory, The Francis Crick Institute, London, United Kingdom
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20
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Sau S, Liu YT, Ma CH, Jayaram M. Stable persistence of the yeast plasmid by hitchhiking on chromosomes during vegetative and germ-line divisions of host cells. Mob Genet Elements 2015; 5:1-8. [PMID: 26442178 DOI: 10.1080/2159256x.2015.1031359] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 03/02/2015] [Accepted: 03/12/2015] [Indexed: 10/23/2022] Open
Abstract
The chromosome-like stability of the Saccharomyces cerevisiae plasmid 2 micron circle likely stems from its ability to tether to chromosomes and segregate by a hitchhiking mechanism. The plasmid partitioning system, responsible for chromosome-coupled segregation, is comprised of 2 plasmid coded proteins Rep1 and Rep2 and a partitioning locus STB. The evidence for the hitchhiking model for mitotic plasmid segregation, although compelling, is almost entirely circumstantial. Direct tests for plasmid-chromosome association are hampered by the limited resolving power of current cell biological tools for analyzing yeast chromosomes. Recent investigations, exploiting the improved resolution of yeast meiotic chromosomes, have revealed the plasmid's propensity to be present at or near chromosome tips. This localization is consistent with the rapid plasmid movements during meiosis I prophase, closely resembling telomere dynamics driven by a meiosis-specific nuclear envelope motor. Current evidence is consistent with the plasmid utilizing the motor as a platform for gaining access to telomeres. Episomes of viruses of the papilloma family and the gammaherpes subfamily persist in latently infected cells by tethering to chromosomes. Selfish genetic elements from fungi to mammals appear to have, by convergent evolution, arrived at the common strategy of chromosome association as a means for stable propagation.
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Affiliation(s)
- Soumitra Sau
- Department of Molecular Biosciences; University of Texas at Austin ; Austin, TX USA
| | - Yen-Ting Liu
- Department of Molecular Biosciences; University of Texas at Austin ; Austin, TX USA
| | - Chien-Hui Ma
- Department of Molecular Biosciences; University of Texas at Austin ; Austin, TX USA
| | - Makkuni Jayaram
- Department of Molecular Biosciences; University of Texas at Austin ; Austin, TX USA
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21
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Sau S, Conrad MN, Lee CY, Kaback DB, Dresser ME, Jayaram M. A selfish DNA element engages a meiosis-specific motor and telomeres for germ-line propagation. ACTA ACUST UNITED AC 2014; 205:643-61. [PMID: 24914236 PMCID: PMC4050733 DOI: 10.1083/jcb.201312002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The yeast 2 micron plasmid engages a meiosis-specific motor that orchestrates telomere-led chromosome movements for its telomere-associated segregation during meiosis I. The chromosome-like mitotic stability of the yeast 2 micron plasmid is conferred by the plasmid proteins Rep1-Rep2 and the cis-acting locus STB, likely by promoting plasmid-chromosome association and segregation by hitchhiking. Our analysis reveals that stable plasmid segregation during meiosis requires the bouquet proteins Ndj1 and Csm4. Plasmid relocalization from the nuclear interior in mitotic cells to the periphery at or proximal to telomeres rises from early meiosis to pachytene. Analogous to chromosomes, the plasmid undergoes Csm4- and Ndj1-dependent rapid prophase movements with speeds comparable to those of telomeres. Lack of Ndj1 partially disrupts plasmid–telomere association without affecting plasmid colocalization with the telomere-binding protein Rap1. The plasmid appears to engage a meiosis-specific motor that orchestrates telomere-led chromosome movements for its telomere-associated segregation during meiosis I. This hitherto uncharacterized mode of germ-line transmission by a selfish genetic element signifies a mechanistic variation within the shared theme of chromosome-coupled plasmid segregation during mitosis and meiosis.
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Affiliation(s)
- Soumitra Sau
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
| | - Michael N Conrad
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Chih-Ying Lee
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - David B Kaback
- Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ 07101
| | - Michael E Dresser
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Makkuni Jayaram
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
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22
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Topological similarity between the 2μm plasmid partitioning locus and the budding yeast centromere: evidence for a common evolutionary origin? Biochem Soc Trans 2013; 41:501-7. [PMID: 23514143 DOI: 10.1042/bst20120224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The partitioning locus STB of the selfish plasmid, the 2μm circle, of Saccharomyces cerevisiae is essential for the propagation of this multi-copy extra-chromosomal DNA element with nearly chromosome-like stability. The functional competence of STB requires the plasmid-coded partitioning proteins Rep1 and Rep2 as well as host-coded proteins. Host factors that associate with STB in a Rep1- and Rep2-dependent manner also interact with centromeres, and play important roles in chromosome segregation. They include the cohesin complex and the centromere-specific histone H3 variant Cse4. The genetically defined point centromere of S. cerevisiae differs starkly from the much more widespread epigenetically specified regional centromeres of eukaryotes. The particularly small size of the S. cerevisiae centromere and the association of chromosome segregation factors with STB raise the possibility of an evolutionary link between these two partitioning loci. The unusual positive supercoiling harboured by the S. cerevisiae centromere and STB in vivo in their functional states, unveiled by recent experiments, bolsters the notion of their potential descent from an ancestral plasmid partitioning locus.
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23
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Chan KM, Liu YT, Ma CH, Jayaram M, Sau S. The 2 micron plasmid of Saccharomyces cerevisiae: A miniaturized selfish genome with optimized functional competence. Plasmid 2013; 70:2-17. [DOI: 10.1016/j.plasmid.2013.03.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/21/2013] [Accepted: 03/02/2013] [Indexed: 01/24/2023]
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24
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Liu YT, Ma CH, Jayaram M. Co-segregation of yeast plasmid sisters under monopolin-directed mitosis suggests association of plasmid sisters with sister chromatids. Nucleic Acids Res 2013; 41:4144-58. [PMID: 23423352 PMCID: PMC3627588 DOI: 10.1093/nar/gkt096] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 01/23/2013] [Accepted: 01/25/2013] [Indexed: 11/13/2022] Open
Abstract
The 2-micron plasmid, a high copy extrachromosomal element in Saccharomyces cerevisiae, propagates itself with nearly the same stability as the chromosomes of its host. Plasmid stability is conferred by a partitioning system consisting of the plasmid-coded proteins Rep1 and Rep2 and a cis-acting locus STB. Circumstantial evidence suggests that the partitioning system couples plasmid segregation to chromosome segregation during mitosis. However, the coupling mechanism has not been elucidated. In order to probe into this question more incisively, we have characterized the segregation of a single-copy STB reporter plasmid by manipulating mitosis to force sister chromatids to co-segregate either without mother-daughter bias or with a finite daughter bias. We find that the STB plasmid sisters are tightly correlated to sister chromatids in the extents of co-segregation as well as the bias in co-segregation under these conditions. Furthermore, this correlation is abolished by delaying spindle organization or preventing cohesin assembly during a cell cycle. Normal segregation of the 2-micron plasmid has been shown to require spindle integrity and the cohesin complex. Our results are accommodated by a model in which spindle- and cohesin-dependent association of plasmid sisters with sister chromatids promotes their segregation by a hitchhiking mechanism.
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Affiliation(s)
| | | | - Makkuni Jayaram
- Section of Molecular Genetics & Microbiology, University of Texas at Austin, Austin, TX 78712, USA
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25
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Ma CH, Cui H, Hajra S, Rowley PA, Fekete C, Sarkeshik A, Ghosh SK, Yates JR, Jayaram M. Temporal sequence and cell cycle cues in the assembly of host factors at the yeast 2 micron plasmid partitioning locus. Nucleic Acids Res 2012; 41:2340-53. [PMID: 23275556 PMCID: PMC3575823 DOI: 10.1093/nar/gks1338] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Saccharomyces cerevisiae 2 micron plasmid exemplifies a benign but selfish genome, whose stability approaches that of the chromosomes of its host. The plasmid partitioning locus STB (stability locus) displays certain functional analogies with centromeres along with critical distinctions, a significant one being the absence of the kinetochore complex at STB. The remodels the structure of chromatin (RSC) chromatin remodeling complex, the nuclear motor Kip1, the histone H3 variant Cse4 and the cohesin complex associate with both loci. These factors appear to contribute to plasmid segregation either directly or indirectly through their roles in chromosome segregation. Assembly and disassembly of the plasmid-coded partitioning proteins Rep1 and Rep2 and host factors at STB follow a temporal hierarchy during the cell cycle. Assembly is initiated by STB association of [Rsc8-Rsc58], followed by [Rep1-Rep2-Kip1] and [Cse4-Rsc2-Sth1] recruitment, and culminates in cohesin assembly. Disassembly starts with dissociation of RSC components, is followed by cohesin disassembly and Cse4 exit during anaphase and late telophase, respectively. [Rep1-Rep2-Kip1] persists through G1 of the ensuing cell cycle. The de novo assembly of the 'partitioning complex' is cued by the innate cell cycle clock and is dependent on DNA replication. Shared functional attributes of STB and centromere (CEN) are consistent with a potential evolutionary link between them.
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Affiliation(s)
- Chien-Hui Ma
- Section of Molecular Genetics & Microbiology, University of Texas at Austin, Austin, TX 78712, USA
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26
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Coffman VC, Wu P, Parthun MR, Wu JQ. CENP-A exceeds microtubule attachment sites in centromere clusters of both budding and fission yeast. ACTA ACUST UNITED AC 2012; 195:563-72. [PMID: 22084306 PMCID: PMC3257534 DOI: 10.1083/jcb.201106078] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The stoichiometries of kinetochores and their constituent proteins in yeast and vertebrate cells were determined using the histone H3 variant CENP-A, known as Cse4 in budding yeast, as a counting standard. One Cse4-containing nucleosome exists in the centromere (CEN) of each chromosome, so it has been assumed that each anaphase CEN/kinetochore cluster contains 32 Cse4 molecules. We report that anaphase CEN clusters instead contained approximately fourfold more Cse4 in Saccharomyces cerevisiae and ~40-fold more CENP-A (Cnp1) in Schizosaccharomyces pombe than predicted. These results suggest that the number of CENP-A molecules exceeds the number of kinetochore-microtubule (MT) attachment sites on each chromosome and that CENP-A is not the sole determinant of kinetochore assembly sites in either yeast. In addition, we show that fission yeast has enough Dam1-DASH complex for ring formation around attached MTs. The results of this study suggest the need for significant revision of existing CEN/kinetochore architectural models.
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Affiliation(s)
- Valerie C Coffman
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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27
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Jayaram M. Association of a centromere specific nucleosome with the yeast plasmid partitioning locus: Implications beyond plasmid partitioning. Mob Genet Elements 2011; 1:203-207. [PMID: 22479687 DOI: 10.4161/mge.1.3.17431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 07/14/2011] [Accepted: 07/15/2011] [Indexed: 11/19/2022] Open
Abstract
The genetically defined point centromeres of budding yeasts and the epigenetically specified regional centromeres of all other eukaryotes harbor a common epigenetic mark in the form of a non-standard nucleosome. Although, the composition of the protein core of the centromere specific nucleosome and the nature of the DNA wrap around it are at present controversial, there is no doubt that this specialized nucleosome harbors a variant of the standard histone H3 (cenH3). The association of cenH3, called Cse4 in Saccharomyces cerevisiae, with the partitioning locus (STB) of the high copy selfish plasmid 2 micron circle that resides in the yeast nucleus and propagates itself stably is intriguing. Recent observations are consistent with Cse4 being a nucleosome component at STB. A common nucleosome identity for the partitioning loci of the chromosomes and the plasmid of yeast support arguments based on evolutionary considerations that the origin of the unusual point centromere of budding yeasts may be traced to the STB locus of an ancestral plasmid.
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Affiliation(s)
- Makkuni Jayaram
- Section of Molecular Genetics and Microbiology; University of Texas at Austin; Austin, TX USA
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28
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Histone H3-variant Cse4-induced positive DNA supercoiling in the yeast plasmid has implications for a plasmid origin of a chromosome centromere. Proc Natl Acad Sci U S A 2011; 108:13671-6. [PMID: 21807992 DOI: 10.1073/pnas.1101944108] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Saccharomyces cerevisiae 2-μm plasmid is a multicopy selfish genome that resides in the nucleus. The genetic organization of the plasmid is optimized for stable, high-copy propagation in host-cell populations. The plasmid's partitioning system poaches host factors, including the centromere-specific histone H3-variant Cse4 and the cohesin complex, enabling replicated plasmid copies to segregate equally in a chromosome-coupled fashion. We have characterized the in vivo chromatin topology of the plasmid partitioning locus STB in its Cse4-associated and Cse4-nonassociated states. We find that the occupancy of Cse4 at STB induces positive DNA supercoiling, with a linking difference (ΔLk) contribution estimated between +1 and +2 units. One plausible explanation for this contrary topology is the presence of a specialized Cse4-containing nucleosome with a right-handed DNA writhe at a functional STB, contrasted by a standard histone H3-containing nucleosome with a left-handed DNA writhe at a nonfunctional STB. The similarities between STB and centromere in their nucleosome signature and DNA topology would be consistent with the potential origin of the unusual point centromere of budding yeast chromosomes from the partitioning locus of an ancestral plasmid.
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Huang CC, Hajra S, Ghosh SK, Jayaram M. Cse4 (CenH3) association with the Saccharomyces cerevisiae plasmid partitioning locus in its native and chromosomally integrated states: implications in centromere evolution. Mol Cell Biol 2011; 31:1030-40. [PMID: 21173161 PMCID: PMC3067819 DOI: 10.1128/mcb.01191-10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 11/29/2010] [Accepted: 12/10/2010] [Indexed: 11/20/2022] Open
Abstract
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 2μm 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.
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Affiliation(s)
- Chu-Chun Huang
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas 78712, Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India
| | - Sujata Hajra
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas 78712, Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India
| | - Santanu Kumar Ghosh
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas 78712, Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India
| | - Makkuni Jayaram
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas 78712, Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India
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Mehta GD, Agarwal MP, Ghosh SK. Centromere identity: a challenge to be faced. Mol Genet Genomics 2010; 284:75-94. [PMID: 20585957 DOI: 10.1007/s00438-010-0553-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 06/16/2010] [Indexed: 11/26/2022]
Abstract
The centromere is a genetic locus, required for faithful chromosome segregation, where spindle fibers attach to the chromosome through kinetochore. Loss of centromere or formation of multiple centromeres on a single chromosome leads to chromosome missegregation or chromosome breakage, respectively, which are detrimental for fitness and survival of a cell. Therefore, understanding the mechanism of centromere locus determination on the chromosome and perpetuation of such a locus in subsequent generation (known as centromere identity) is very fundamental to combat conditions like aneuploidy, spontaneous abortion, developmental defects, cell lethality and cancer. Recent studies have come up with different models to explain centromere identity. However, the exact mechanism still remains elusive. It has been observed that most eukaryotic centromeres are determined epigenetically rather than by a DNA sequence. The epigenetic marks that are instrumental in determining centromere identity are the histone H3 variant, CENP-A and the specialized posttranslational modification of the core histones. Here we will review the recent studies on the factors responsible for generating unique centromeric chromatin and how it perpetuates during cell division giving the present-day models. We will further focus on the probable mechanism of de novo centromere formation with an example of neocentromere. As a matter of similitude, this review will include marking extrachromosomal chromatin to be served as a partitioning locus by deposition of CENP-A homolog in budding yeast.
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Affiliation(s)
- Gunjan D Mehta
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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Ghosh SK, Huang CC, Hajra S, Jayaram M. Yeast cohesin complex embraces 2 micron plasmid sisters in a tri-linked catenane complex. Nucleic Acids Res 2010; 38:570-84. [PMID: 19920123 PMCID: PMC2811031 DOI: 10.1093/nar/gkp993] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2009] [Revised: 10/15/2009] [Accepted: 10/16/2009] [Indexed: 11/30/2022] Open
Abstract
Sister chromatid cohesion, crucial for faithful segregation of replicated chromosomes in eukaryotes, is mediated by the multi-subunit protein complex cohesin. The Saccharomyces cerevisiae plasmid 2 micron circle mimics chromosomes in assembling cohesin at its partitioning locus. The plasmid is a multi-copy selfish DNA element that resides in the nucleus and propagates itself stably, presumably with assistance from cohesin. In metaphase cell lysates, or fractions enriched for their cohesed state by sedimentation, plasmid molecules are trapped topologically by the protein ring formed by cohesin. They can be released from cohesin's embrace either by linearizing the DNA or by cleaving a cohesin subunit. Assays using two distinctly tagged cohesin molecules argue against the hand-cuff (an associated pair of monomeric cohesin rings) or the bracelet (a dimeric cohesin ring) model as responsible for establishing plasmid cohesion. Our cumulative results most easily fit a model in which a single monomeric cohesin ring, rather than a series of such rings, conjoins a pair of sister plasmids. These features of plasmid cohesion account for its sister-to-sister mode of segregation by cohesin disassembly during anaphase. The mechanistic similarities of cohesion between mini-chromosome sisters and 2 micron plasmid sisters suggest a potential kinship between the plasmid partitioning locus and centromeres.
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Affiliation(s)
- Santanu K. Ghosh
- School of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India and Section of Molecular Genetics & Microbiology, University of Texas at Austin, Austin, TX 78712, USA
| | - Chu-Chun Huang
- School of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India and Section of Molecular Genetics & Microbiology, University of Texas at Austin, Austin, TX 78712, USA
| | - Sujata Hajra
- School of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India and Section of Molecular Genetics & Microbiology, University of Texas at Austin, Austin, TX 78712, USA
| | - Makkuni Jayaram
- School of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai 400076, India and Section of Molecular Genetics & Microbiology, University of Texas at Austin, Austin, TX 78712, USA
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Abstract
Centromeres are chromosomal elements that are both necessary and sufficient for chromosome segregation. However, the puzzlingly broad range in centromere complexity, from simple "point" centromeres to multi-megabase arrays of DNA satellites, has defied explanation. We posit that ancestral centromeres were epigenetically defined and that point centromeres, such as those of budding yeast, have derived from the partitioning elements of selfish plasmids. We further propose that the larger centromere sizes in plants and animals and the rapid evolution of their centromeric proteins is the result of an intense battle for evolutionary dominance due to the asymmetric retention of only one product of female meiosis.
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Affiliation(s)
- Harmit S Malik
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
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Leslie M. A plasmid goes motoring. J Biophys Biochem Cytol 2009. [PMCID: PMC2673550 DOI: 10.1083/jcb.1852if] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Cui H, Ghosh SK, Jayaram M. The selfish yeast plasmid uses the nuclear motor Kip1p but not Cin8p for its localization and equal segregation. J Cell Biol 2009; 185:251-64. [PMID: 19364922 PMCID: PMC2700366 DOI: 10.1083/jcb.200810130] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 03/23/2009] [Indexed: 01/31/2023] Open
Abstract
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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Affiliation(s)
- Hong Cui
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA
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Current awareness on yeast. Yeast 2008. [DOI: 10.1002/yea.1458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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