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Williams TC, Kroukamp H, Xu X, Wightman EL, Llorente B, Borneman AR, Carpenter AC, Van Wyk N, Meier F, Collier TR, Espinosa MI, Daniel EL, Walker RS, Cai Y, Nevalainen HK, Curach NC, Deveson IW, Mercer TR, Johnson DL, Mitchell LA, Bader JS, Stracquadanio G, Boeke JD, Goold HD, Pretorius IS, Paulsen IT. Parallel laboratory evolution and rational debugging reveal genomic plasticity to S. cerevisiae synthetic chromosome XIV defects. CELL GENOMICS 2023; 3:100379. [PMID: 38020977 PMCID: PMC10667330 DOI: 10.1016/j.xgen.2023.100379] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 12/01/2023]
Abstract
Synthetic chromosome engineering is a complex process due to the need to identify and repair growth defects and deal with combinatorial gene essentiality when rearranging chromosomes. To alleviate these issues, we have demonstrated novel approaches for repairing and rearranging synthetic Saccharomyces cerevisiae genomes. We have designed, constructed, and restored wild-type fitness to a synthetic 753,096-bp version of S. cerevisiae chromosome XIV as part of the Synthetic Yeast Genome project. In parallel to the use of rational engineering approaches to restore wild-type fitness, we used adaptive laboratory evolution to generate a general growth-defect-suppressor rearrangement in the form of increased TAR1 copy number. We also extended the utility of the synthetic chromosome recombination and modification by loxPsym-mediated evolution (SCRaMbLE) system by engineering synthetic-wild-type tetraploid hybrid strains that buffer against essential gene loss, highlighting the plasticity of the S. cerevisiae genome in the presence of rational and non-rational modifications.
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Affiliation(s)
- Thomas C. Williams
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- CSIRO Synthetic Biology Future Science Platform, Canberra, ACT 2601, Australia
| | - Heinrich Kroukamp
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Xin Xu
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Elizabeth L.I. Wightman
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Briardo Llorente
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- CSIRO Synthetic Biology Future Science Platform, Canberra, ACT 2601, Australia
- The Australian Genome Foundry, Sydney, NSW, Australia
| | - Anthony R. Borneman
- The Australian Wine Research Institute, Adelaide, SA 5064, Australia
- School of Agriculture, Food & Wine, Faculty of Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Alexander C. Carpenter
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- CSIRO Synthetic Biology Future Science Platform, Canberra, ACT 2601, Australia
| | - Niel Van Wyk
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- Department of Microbiology and Biochemistry, Hochschule Geisenheim University, Geisenheim, Germany
| | - Felix Meier
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Thomas R.V. Collier
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Monica I. Espinosa
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Elizabeth L. Daniel
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Roy S.K. Walker
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
- School of Engineering, Institute for Bioengineering, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Yizhi Cai
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - Helena K.M. Nevalainen
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Natalie C. Curach
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- Bioplatforms Australia, Research Park Drive, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Ira W. Deveson
- St Vincent’s Clinical School, University of New South Wales, Sydney, NSW 2010, Australia
- The Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Timothy R. Mercer
- St Vincent’s Clinical School, University of New South Wales, Sydney, NSW 2010, Australia
- The Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD, Australia
| | - Daniel L. Johnson
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- The Australian Wine Research Institute, Adelaide, SA 5064, Australia
| | - Leslie A. Mitchell
- Institute for Systems Genetics, NYU Langone Health, New York, NY 10016, USA
| | - Joel S. Bader
- Department of Biomedical Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Giovanni Stracquadanio
- Institute of Quantitative Biology, Biochemistry, and Biotechnology, SynthSys, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Jef D. Boeke
- Institute for Systems Genetics, NYU Langone Health, New York, NY 10016, USA
- Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA
- Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY 11201, USA
| | - Hugh D. Goold
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- New South Wales Department of Primary Industries, Orange, NSW 2800, Australia
| | - Isak S. Pretorius
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
| | - Ian T. Paulsen
- School of Natural Sciences, ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- The Australian Genome Foundry, Sydney, NSW, Australia
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Schoonover MG, Chilson EC, Strome ED. Heterozygous Mutations in Aromatic Amino Acid Synthesis Genes Trigger TOR Pathway Activation in Saccharomyces cerevisiae.. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000685. [PMID: 36468155 PMCID: PMC9713580 DOI: 10.17912/micropub.biology.000685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/02/2022] [Accepted: 11/15/2022] [Indexed: 01/25/2023]
Abstract
The highly conserved complexes of Target of Rapamycin (TORC1 and TORC2) are central regulators to many vital cellular processes including growth and autophagy in response to nutrient availability. Previous research has extensively elucidated exogenous nutrient control on TORC1/TORC2; however, little is known about the potential alteration of nutrient pools from mutations in biosynthesis pathways and their impact on Tor pathway activity. Here, we analyze the impacts of heterozygous mutations in aromatic amino acid biosynthesis genes on TOR signaling via differential expression of genes downstream of TORC1 and autophagy induction for TORC1 and TORC2 activity.
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Rapid Colorimetric Detection of Genome Evolution in SCRaMbLEd Synthetic Saccharomyces cerevisiae Strains. Microorganisms 2020; 8:microorganisms8121914. [PMID: 33271913 PMCID: PMC7761333 DOI: 10.3390/microorganisms8121914] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 11/28/2020] [Accepted: 11/30/2020] [Indexed: 11/16/2022] Open
Abstract
Genome-scale engineering and custom synthetic genomes are reshaping the next generation of industrial yeast strains. The Cre-recombinase-mediated chromosomal rearrangement mechanism of designer synthetic Saccharomyces cerevisiae chromosomes, known as SCRaMbLE, is a powerful tool which allows rapid genome evolution upon command. This system is able to generate millions of novel genomes with potential valuable phenotypes, but the excessive loss of essential genes often results in poor growth or even the death of cells with useful phenotypes. In this study we expanded the versatility of SCRaMbLE to industrial strains, and evaluated different control measures to optimize genomic rearrangement, whilst limiting cell death. To achieve this, we have developed RED (rapid evolution detection), a simple colorimetric plate-assay procedure to rapidly quantify the degree of genomic rearrangements within a post-SCRaMbLE yeast population. RED-enabled semi-synthetic strains were mated with the haploid progeny of industrial yeast strains to produce stress-tolerant heterozygous diploid strains. Analysis of these heterozygous strains with the RED-assay, genome sequencing and custom bioinformatics scripts demonstrated a correlation between RED-assay frequencies and physical genomic rearrangements. Here we show that RED is a fast and effective method to evaluate the optimal SCRaMbLE induction times of different Cre-recombinase expression systems for the development of industrial strains.
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Single-Gene Deletions Contributing to Loss of Heterozygosity in Saccharomyces cerevisiae: Genome-Wide Screens and Reproducibility. G3-GENES GENOMES GENETICS 2019; 9:2835-2850. [PMID: 31270132 PMCID: PMC6723133 DOI: 10.1534/g3.119.400429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Loss of heterozygosity (LOH) is a phenomenon commonly observed in cancers; the loss of chromosomal regions can be both causal and indicative of underlying genome instability. Yeast has long been used as a model organism to study genetic mechanisms difficult to study in mammalian cells. Studying gene deletions leading to increased LOH in yeast aids our understanding of the processes involved, and guides exploration into the etiology of LOH in cancers. Yet, before in-depth mechanistic studies can occur, candidate genes of interest must be identified. Utilizing the heterozygous Saccharomyces cerevisiae deletion collection (≈ 6500 strains), 217 genes whose disruption leads to increased LOH events at the endogenously heterozygous mating type locus were identified. Our investigation to refine this list of genes to candidates with the most definite impact on LOH includes: secondary testing for LOH impact at an additional locus, gene ontology analysis to determine common gene characteristics, and positional gene enrichment studies to identify chromosomal regions important in LOH events. Further, we conducted extensive comparisons of our data to screens with similar, but distinct methodologies, to further distinguish genes that are more likely to be true contributors to instability due to their reproducibility, and not just identified due to the stochastic nature of LOH. Finally, we selected nine candidate genes and quantitatively measured their impact on LOH as a benchmark for the impact of genes identified in our study. Our data add to the existing body of work and strengthen the evidence of single-gene knockdowns contributing to genome instability.
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Hoffert KM, Higginbotham KSP, Gibson JT, Oehrle S, Strome ED. Mutations in the S-Adenosylmethionine Synthetase Genes SAM1 and SAM2 Differentially Affect Genome Stability in Saccharomyces cerevisiae. Genetics 2019; 213:97-112. [PMID: 31320408 PMCID: PMC6727793 DOI: 10.1534/genetics.119.302435] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 07/15/2019] [Indexed: 12/20/2022] Open
Abstract
Maintenance of genome integrity is a crucial cellular focus that involves a wide variety of proteins functioning in multiple processes. Defects in many different pathways can result in genome instability, a hallmark of cancer. Utilizing a diploid Saccharomyces cerevisiae model, we previously reported a collection of gene mutations that affect genome stability in a haploinsufficient state. In this work we explore the effect of gene dosage on genome instability for one of these genes and its paralog; SAM1 and SAM2 These genes encode S-Adenosylmethionine (AdoMet) synthetases, responsible for the creation of AdoMet from methionine and ATP. AdoMet is the universal methyl donor for methylation reactions and is essential for cell viability. It is the second most used cellular enzyme substrate and is exceptionally well-conserved through evolution. Mammalian cells express three genes, MAT1A, MAT2A, and MAT2B, with distinct expression profiles and functions. Alterations to these AdoMet synthetase genes, and AdoMet levels, are found in many cancers, making them a popular target for therapeutic intervention. However, significant variance in these alterations are found in different tumor types, with the cellular consequences of the variation still unknown. By studying this pathway in the yeast system, we demonstrate that losses of SAM1 and SAM2 have different effects on genome stability through distinctive effects on gene expression and AdoMet levels, and ultimately separate effects on the methyl cycle. Thus, this study provides insight into the mechanisms by which differential expression of the SAM genes have cellular consequences that affect genome instability.
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Affiliation(s)
- Kellyn M Hoffert
- Department of Biological Sciences, Northern Kentucky University, Highland Heights, Kentucky 41099
| | - Kathryn S P Higginbotham
- Department of Biological Sciences, Northern Kentucky University, Highland Heights, Kentucky 41099
| | - Justin T Gibson
- Department of Biological Sciences, Northern Kentucky University, Highland Heights, Kentucky 41099
| | - Stuart Oehrle
- Waters Field Laboratory, Chemistry Department, Northern Kentucky University, Highland Heights, Kentucky 41099
| | - Erin D Strome
- Department of Biological Sciences, Northern Kentucky University, Highland Heights, Kentucky 41099
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6
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Coelho MC, Pinto RM, Murray AW. Heterozygous mutations cause genetic instability in a yeast model of cancer evolution. Nature 2019; 566:275-278. [PMID: 30700905 DOI: 10.1038/s41586-019-0887-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 12/18/2018] [Indexed: 12/26/2022]
Abstract
Genetic instability, a heritable increase in the rate of genetic mutation, accelerates evolutionary adaptation1 and is widespread in cancer2,3. In mammals, instability can arise from damage to both copies of genes involved in DNA metabolism and cell cycle regulation4 or from inactivation of one copy of a gene whose product is present in limiting amounts (haploinsufficiency5); however, it has proved difficult to determine the relative importance of these two mechanisms. In Escherichia coli6, the application of repeated, strong selection enriches for genetic instability. Here we have used this approach to evolve genetic instability in diploid cells of the budding yeast Saccharomyces cerevisiae, and have isolated clones with increased rates of point mutation, mitotic recombination, and chromosome loss. We identified candidate, heterozygous, instability-causing mutations; engineering these mutations, as heterozygotes, into the ancestral diploid strain caused genetic instability. Mutations that inactivated one copy of haploinsufficient genes were more common than those that dominantly altered the function of the mutated gene copy. The mutated genes were enriched for genes functioning in transport, protein quality control, and DNA metabolism, and have revealed new targets for genetic instability7-11, including essential genes. Although only a minority (10 out of 57 genes with orthologues or close homologues) of the targets we identified have homologous human genes that have been implicated in cancer2, the remainder are candidates to contribute to human genetic instability. To test this hypothesis, we inactivated six examples in a near-haploid human cell line; five of these mutations increased instability. We conclude that single genetic events cause genetic instability in diploid yeast cells, and propose that similar, heterozygous mutations in mammalian homologues initiate genetic instability in cancer.
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Affiliation(s)
- Miguel C Coelho
- FAS Center for Systems Biology, Harvard University, Cambridge, MA, USA. .,Molecular and Cell Biology, Harvard University, Cambridge, MA, USA. .,Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
| | - Ricardo M Pinto
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Andrew W Murray
- FAS Center for Systems Biology, Harvard University, Cambridge, MA, USA. .,Molecular and Cell Biology, Harvard University, Cambridge, MA, USA.
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7
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Chevet E, Hetz C, Samali A. Endoplasmic reticulum stress-activated cell reprogramming in oncogenesis. Cancer Discov 2015; 5:586-97. [PMID: 25977222 DOI: 10.1158/2159-8290.cd-14-1490] [Citation(s) in RCA: 270] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 04/28/2015] [Indexed: 12/29/2022]
Abstract
UNLABELLED Stress induced by the accumulation of unfolded proteins in the endoplasmic reticulum (ER) is observed in many human diseases, including cancers. Cellular adaptation to ER stress is mediated by the unfolded protein response (UPR), which aims at restoring ER homeostasis. The UPR has emerged as a major pathway in remodeling cancer gene expression, thereby either preventing cell transformation or providing an advantage to transformed cells. UPR sensors are highly regulated by the formation of dynamic protein scaffolds, leading to integrated reprogramming of the cells. Herein, we describe the regulatory mechanisms underlying UPR signaling upon cell intrinsic or extrinsic challenges, and how they engage cell transformation programs and/or provide advantages to cancer cells, leading to enhanced aggressiveness or chemoresistance. We discuss the emerging cross-talk between the UPR and related metabolic processes to ensure maintenance of protein homeostasis and its impact on cell transformation and tumor growth. SIGNIFICANCE ER stress signaling is dysregulated in many forms of cancer and contributes to tumor growth as a survival factor, in addition to modulating other disease-associated processes, including cell migration, cell transformation, and angiogenesis. Evidence for targeting the ER stress signaling pathway as an anticancer strategy is compelling, and novel agents that selectively inhibit the UPR have demonstrated preliminary evidence of preclinical efficacy with an acceptable safety profile.
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Affiliation(s)
- Eric Chevet
- Oncogenesis, Stress, Cancer, University of Rennes, Rennes, France. Centre de Lutte Contre le Cancer Eugène Marquis, Rennes, France.
| | - Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile. Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Santiago, Chile. Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts.
| | - Afshin Samali
- Apoptosis Research Centre, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
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Dufey E, Urra H, Hetz C. ER proteostasis addiction in cancer biology: Novel concepts. Semin Cancer Biol 2015; 33:40-7. [PMID: 25931388 DOI: 10.1016/j.semcancer.2015.04.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 04/15/2015] [Accepted: 04/20/2015] [Indexed: 01/22/2023]
Abstract
Endoplasmic reticulum (ER) stress is generated by various physiological and pathological conditions that induce an accumulation of misfolded proteins in its lumen. ER stress activates the unfolded protein response (UPR), an adaptive reaction to cope with protein misfolding to and restore proteostasis. However, chronic ER stress results in apoptosis. In solid tumors, the UPR mediates adaptation to various environmental stressors, including hypoxia, low in pH and low nutrients availability, driving positive selection. Recent findings support the concept that UPR signaling also contributes to other relevant cancer-related event that may not be related to ER stress, including angiogenesis, genomic instability, metastasis and immunomodulation. In this article, we overview novel discoveries highlighting the impact of the UPR to different aspects of cancer biology beyond its known role as a survival factor to the hypoxic environment observed in solid tumors.
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Affiliation(s)
- Estefanie Dufey
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Hery Urra
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, Faculty of Medicine, University of Chile, Santiago, Chile; Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA.
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Abstract
Errors in mitosis are a primary cause of chromosome instability (CIN), generating aneuploid progeny cells. Whereas a variety of factors can influence CIN, under most conditions mitotic errors are rare events that have been difficult to measure accurately. Here we report a green fluorescent protein−based quantitative chromosome transmission fidelity (qCTF) assay in budding yeast that allows sensitive and quantitative detection of CIN and can be easily adapted to high-throughput analysis. Using the qCTF assay, we performed genome-wide quantitative profiling of genes that affect CIN in a dosage-dependent manner and identified genes that elevate CIN when either increased (icCIN) or decreased in copy number (dcCIN). Unexpectedly, qCTF screening also revealed genes whose change in copy number quantitatively suppress CIN, suggesting that the basal error rate of the wild-type genome is not minimized, but rather, may have evolved toward an optimal level that balances both stability and low-level karyotype variation for evolutionary adaptation.
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A FACS-optimized screen identifies regulators of genome stability in Candida albicans. EUKARYOTIC CELL 2015; 14:311-22. [PMID: 25595446 DOI: 10.1128/ec.00286-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Loss of heterozygosity (LOH) plays important roles in genome dynamics, notably, during tumorigenesis. In the fungal pathogen Candida albicans, LOH contributes to the acquisition of antifungal resistance. In order to investigate the mechanisms that regulate LOH in C. albicans, we have established a novel method combining an artificial heterozygous locus harboring the blue fluorescent protein and green fluorescent protein markers and flow cytometry to detect LOH events at the single-cell level. Using this fluorescence-based method, we have confirmed that elevated temperature, treatment with methyl methanesulfonate, and inactivation of the Mec1 DNA damage checkpoint kinase triggered an increase in the frequency of LOH. Taking advantage of this system, we have searched for C. albicans genes whose overexpression triggered an increase in LOH and identified four candidates, some of which are known regulators of genome dynamics with human homologues contributing to cancer progression. Hence, the approach presented here will allow the implementation of new screens to identify genes that are important for genome stability in C. albicans and more generally in eukaryotic cells.
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Newman TJ, Mamun MA, Nieduszynski CA, Blow JJ. Replisome stall events have shaped the distribution of replication origins in the genomes of yeasts. Nucleic Acids Res 2013; 41:9705-18. [PMID: 23963700 PMCID: PMC3834809 DOI: 10.1093/nar/gkt728] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/24/2013] [Accepted: 07/25/2013] [Indexed: 01/21/2023] Open
Abstract
During S phase, the entire genome must be precisely duplicated, with no sections of DNA left unreplicated. Here, we develop a simple mathematical model to describe the probability of replication failing due to the irreversible stalling of replication forks. We show that the probability of complete genome replication is maximized if replication origins are evenly spaced, the largest inter-origin distances are minimized, and the end-most origins are positioned close to chromosome ends. We show that origin positions in the yeast Saccharomyces cerevisiae genome conform to all three predictions thereby maximizing the probability of complete replication if replication forks stall. Origin positions in four other yeasts-Kluyveromyces lactis, Lachancea kluyveri, Lachancea waltii and Schizosaccharomyces pombe-also conform to these predictions. Equating failure rates at chromosome ends with those in chromosome interiors gives a mean per nucleotide fork stall rate of ∼5 × 10(-8), which is consistent with experimental estimates. Using this value in our theoretical predictions gives replication failure rates that are consistent with data from replication origin knockout experiments. Our theory also predicts that significantly larger genomes, such as those of mammals, will experience a much greater probability of replication failure genome-wide, and therefore will likely require additional compensatory mechanisms.
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Affiliation(s)
- Timothy J. Newman
- College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK, School of Engineering, Physics and Mathematics, University of Dundee, Dundee, DD1 4HN, UK and Centre for Genetics and Genomics, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Mohammed A. Mamun
- College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK, School of Engineering, Physics and Mathematics, University of Dundee, Dundee, DD1 4HN, UK and Centre for Genetics and Genomics, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Conrad A. Nieduszynski
- College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK, School of Engineering, Physics and Mathematics, University of Dundee, Dundee, DD1 4HN, UK and Centre for Genetics and Genomics, University of Nottingham, Nottingham, NG7 2UH, UK
| | - J. Julian Blow
- College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK, School of Engineering, Physics and Mathematics, University of Dundee, Dundee, DD1 4HN, UK and Centre for Genetics and Genomics, University of Nottingham, Nottingham, NG7 2UH, UK
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12
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Choy JS, O'Toole E, Schuster BM, Crisp MJ, Karpova TS, McNally JG, Winey M, Gardner MK, Basrai MA. Genome-wide haploinsufficiency screen reveals a novel role for γ-TuSC in spindle organization and genome stability. Mol Biol Cell 2013; 24:2753-63. [PMID: 23825022 PMCID: PMC3756926 DOI: 10.1091/mbc.e12-12-0902] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 06/19/2013] [Accepted: 06/24/2013] [Indexed: 02/02/2023] Open
Abstract
How subunit dosage contributes to the assembly and function of multimeric complexes is an important question with implications in understanding biochemical, evolutionary, and disease mechanisms. Toward identifying pathways that are susceptible to decreased gene dosage, we performed a genome-wide screen for haploinsufficient (HI) genes that guard against genome instability in Saccharomyces cerevisiae. This led to the identification of all three genes (SPC97, SPC98, and TUB4) encoding the evolutionarily conserved γ-tubulin small complex (γ-TuSC), which nucleates microtubule assembly. We found that hemizygous γ-TuSC mutants exhibit higher rates of chromosome loss and increases in anaphase spindle length and elongation velocities. Fluorescence microscopy, fluorescence recovery after photobleaching, electron tomography, and model convolution simulation of spc98/+ mutants revealed improper regulation of interpolar (iMT) and kinetochore (kMT) microtubules in anaphase. The underlying cause is likely due to reduced levels of Tub4, as overexpression of TUB4 suppressed the spindle and chromosome segregation defects in spc98/+ mutants. We propose that γ-TuSC is crucial for balanced assembly between iMTs and kMTs for spindle organization and accurate chromosome segregation. Taken together, the results show how gene dosage studies provide critical insights into the assembly and function of multisubunit complexes that may not be revealed by using traditional studies with haploid gene deletion or conditional alleles.
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Affiliation(s)
- John S. Choy
- Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Eileen O'Toole
- Department of Cellular and Developmental Biology, University of Colorado–Boulder, Boulder, CO 80309
| | - Breanna M. Schuster
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Matthew J. Crisp
- Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Tatiana S. Karpova
- Fluorescent Imaging Facility, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - James G. McNally
- Fluorescent Imaging Facility, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Mark Winey
- Department of Cellular and Developmental Biology, University of Colorado–Boulder, Boulder, CO 80309
| | - Melissa K. Gardner
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Munira A. Basrai
- Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
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13
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Schmitzberger F, Harrison SC. RWD domain: a recurring module in kinetochore architecture shown by a Ctf19-Mcm21 complex structure. EMBO Rep 2012; 13:216-22. [PMID: 22322944 DOI: 10.1038/embor.2012.1] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 12/14/2011] [Accepted: 12/20/2011] [Indexed: 01/10/2023] Open
Abstract
The proteins Ctf19, Okp1, Mcm21 and Ame1 are the components of COMA, a subassembly of budding-yeast kinetochores. We have determined the crystal structure of a conserved COMA subcomplex--the Ctf19-Mcm21 heterodimer--from Kluyveromyces lactis. Both proteins contain 'double-RWD' domains, which together form a Y-shaped framework with flexible N-terminal extensions. The kinetochore proteins Csm1, Spc24 and Spc25 have related single RWD domains, and Ctf19 and Mcm21 associate with pseudo-twofold symmetry analogous to that in the Csm1 homodimer and the Spc24-Spc25 heterodimer. The double-RWD domain core of the Ctf19-Mcm21 heterodimer is sufficient for association with Okp1-Ame1; the less conserved N-terminal regions may interact with components of a more extensive 'CTF19 complex'. Our structure shows the RWD domain to be a recurring module of kinetochore architecture that may be present in other kinetochore substructures. Like many eukaryotic molecular machines, kinetochores may have evolved from simpler assemblies by multiplication of a few ancestral modules.
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Affiliation(s)
- Florian Schmitzberger
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 250 Longwood Avenue, Boston, Massachusetts 02115, USA
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Henry KA, Blank HM, Hoose SA, Polymenis M. The unfolded protein response is not necessary for the G1/S transition, but it is required for chromosome maintenance in Saccharomyces cerevisiae. PLoS One 2010; 5:e12732. [PMID: 20856872 PMCID: PMC2939067 DOI: 10.1371/journal.pone.0012732] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2010] [Accepted: 08/23/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The unfolded protein response (UPR) is a eukaryotic signaling pathway, from the endoplasmic reticulum (ER) to the nucleus. Protein misfolding in the ER triggers the UPR. Accumulating evidence links the UPR in diverse aspects of cellular homeostasis. The UPR responds to the overall protein synthesis capacity and metabolic fluxes of the cell. Because the coupling of metabolism with cell division governs when cells start dividing, here we examined the role of UPR signaling in the timing of initiation of cell division and cell cycle progression, in the yeast Saccharomyces cerevisiae. METHODOLOGY/PRINCIPAL FINDINGS We report that cells lacking the ER-resident stress sensor Ire1p, which cannot trigger the UPR, nonetheless completed the G1/S transition on time. Furthermore, loss of UPR signaling neither affected the nutrient and growth rate dependence of the G1/S transition, nor the metabolic oscillations that yeast cells display in defined steady-state conditions. Remarkably, however, loss of UPR signaling led to hypersensitivity to genotoxic stress and a ten-fold increase in chromosome loss. CONCLUSIONS/SIGNIFICANCE Taken together, our results strongly suggest that UPR signaling is not necessary for the normal coupling of metabolism with cell division, but it has a role in genome maintenance. These results add to previous work that linked the UPR with cytokinesis in yeast. UPR signaling is conserved in all eukaryotes, and it malfunctions in a variety of diseases, including cancer. Therefore, our findings may be relevant to other systems, including humans.
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Affiliation(s)
- Kelsey A. Henry
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Heidi M. Blank
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Scott A. Hoose
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Michael Polymenis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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Covo S, Westmoreland JW, Gordenin DA, Resnick MA. Cohesin Is limiting for the suppression of DNA damage-induced recombination between homologous chromosomes. PLoS Genet 2010; 6:e1001006. [PMID: 20617204 PMCID: PMC2895640 DOI: 10.1371/journal.pgen.1001006] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 05/27/2010] [Indexed: 01/09/2023] Open
Abstract
Double-strand break (DSB) repair through homologous recombination (HR) is an evolutionarily conserved process that is generally error-free. The risk to genome stability posed by nonallelic recombination or loss-of-heterozygosity could be reduced by confining HR to sister chromatids, thereby preventing recombination between homologous chromosomes. Here we show that the sister chromatid cohesion complex (cohesin) is a limiting factor in the control of DSB repair and genome stability and that it suppresses DNA damage-induced interactions between homologues. We developed a gene dosage system in tetraploid yeast to address limitations on various essential components in DSB repair and HR. Unlike RAD50 and RAD51, which play a direct role in HR, a 4-fold reduction in the number of essential MCD1 sister chromatid cohesion subunit genes affected survival of gamma-irradiated G(2)/M cells. The decreased survival reflected a reduction in DSB repair. Importantly, HR between homologous chromosomes was strongly increased by ionizing radiation in G(2)/M cells with a single copy of MCD1 or SMC3 even at radiation doses where survival was high and DSB repair was efficient. The increased recombination also extended to nonlethal doses of UV, which did not induce DSBs. The DNA damage-induced recombinants in G(2)/M cells included crossovers. Thus, the cohesin complex has a dual role in protecting chromosome integrity: it promotes DSB repair and recombination between sister chromatids, and it suppresses damage-induced recombination between homologues. The effects of limited amounts of Mcd1and Smc3 indicate that small changes in cohesin levels may increase the risk of genome instability, which may lead to genetic diseases and cancer.
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Affiliation(s)
- Shay Covo
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Research Triangle Park, North Carolina, United States of America
| | - James W. Westmoreland
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Research Triangle Park, North Carolina, United States of America
| | - Dmitry A. Gordenin
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Research Triangle Park, North Carolina, United States of America
| | - Michael A. Resnick
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Research Triangle Park, North Carolina, United States of America
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Wu X, Strome ED, Meng Q, Hastings PJ, Plon SE, Kimmel M. A robust estimator of mutation rates. Mutat Res 2009; 661:101-109. [PMID: 19100753 DOI: 10.1016/j.mrfmmm.2008.11.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 11/13/2008] [Accepted: 11/21/2008] [Indexed: 05/27/2023]
Abstract
Fluctuation analysis is an established and widely used technique of estimating mutation rates in cultured cells. This paper presents a modified median estimator of mutation rates, which is novel because it allows for unequal population sizes N(t) of the parallel cultures, and helps to detect and reduce the estimation variability. Simulation results show a good accuracy and robustness of the modified median estimator compared with the median estimator and the maximum likelihood estimator. The proposed estimator, based on the Luria-Delbrück model, is applied to 20 yeast datasets collected during 3 different days for a study of chromosome loss and recombination in wild-type Saccharomyces cerevisiae strains. The estimates obtained display among-experiment variability, which is inflated with respect to the model predictions on simulated data. Further investigation in S. cerevisiae and Escherichia coli uncovers an empirical inverse relationship between the population sizes N(t) and the mutation rate estimates under certain experimental conditions. The impact of these effects on the practice of fluctuation analysis is discussed.
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Affiliation(s)
- Xiaowei Wu
- Department of Statistics, Rice University, Houston, TX 77005, USA.
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Current awareness on yeast. Yeast 2008. [DOI: 10.1002/yea.1558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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