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Jiang L, Shen Y, Jiang Y, Mei W, Wei L, Feng J, Wei C, Liao X, Mo Y, Pan L, Wei M, Gu Y, Zheng J. Amino acid metabolism and MAP kinase signaling pathway play opposite roles in the regulation of ethanol production during fermentation of sugarcane molasses in budding yeast. Genomics 2024; 116:110811. [PMID: 38387766 DOI: 10.1016/j.ygeno.2024.110811] [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: 11/03/2023] [Revised: 02/15/2024] [Accepted: 02/19/2024] [Indexed: 02/24/2024]
Abstract
Sugarcane molasses is one of the main raw materials for bioethanol production, and Saccharomyces cerevisiae is the major biofuel-producing organism. In this study, a batch fermentation model has been used to examine ethanol titers of deletion mutants for all yeast nonessential genes in this yeast genome. A total of 42 genes are identified to be involved in ethanol production during fermentation of sugarcane molasses. Deletion mutants of seventeen genes show increased ethanol titers, while deletion mutants for twenty-five genes exhibit reduced ethanol titers. Two MAP kinases Hog1 and Kss1 controlling the high osmolarity and glycerol (HOG) signaling and the filamentous growth, respectively, are negatively involved in the regulation of ethanol production. In addition, twelve genes involved in amino acid metabolism are crucial for ethanol production during fermentation. Our findings provide novel targets and strategies for genetically engineering industrial yeast strains to improve ethanol titer during fermentation of sugarcane molasses.
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Affiliation(s)
- Linghuo Jiang
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China.
| | - Yuzhi Shen
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Yongqiang Jiang
- Institute of Biology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Weiping Mei
- Institute of Eco-Environmental Research, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Liudan Wei
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Jinrong Feng
- Pathogen Biology Department, Nantong University, Nantong, Jiangsu 226001, China
| | - Chunyu Wei
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Xiufan Liao
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Yiping Mo
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Lingxin Pan
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Min Wei
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Yiying Gu
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
| | - Jiashi Zheng
- Laboratory of Yeast Biology and Fermentation Technology, National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Biomass Engineering Technology Research Center, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China
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2
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Gantz VM, Bier E. Active genetics comes alive: Exploring the broad applications of CRISPR-based selfish genetic elements (or gene-drives): Exploring the broad applications of CRISPR-based selfish genetic elements (or gene-drives). Bioessays 2022; 44:e2100279. [PMID: 35686327 PMCID: PMC9397133 DOI: 10.1002/bies.202100279] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 05/06/2022] [Accepted: 05/10/2022] [Indexed: 11/11/2022]
Abstract
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-based "active genetic" elements developed in 2015 bypassed the fundamental rules of traditional genetics. Inherited in a super-Mendelian fashion, such selfish genetic entities offered a variety of potential applications including: gene-drives to disseminate gene cassettes carrying desired traits throughout insect populations to control disease vectors or pest species, allelic drives biasing inheritance of preferred allelic variants, neutralizing genetic elements to delete and replace or to halt the spread of gene-drives, split-drives with the core constituent Cas9 endonuclease and guide RNA (gRNA) components inserted at separate genomic locations to accelerate assembly of complex arrays of genetic traits or to gain genetic entry into novel organisms (vertebrates, plants, bacteria), and interhomolog based copying systems in somatic cells to develop tools for treating inherited or infectious diseases. Here, we summarize the substantial advances that have been made on all of these fronts and look forward to the next phase of this rapidly expanding and impactful field.
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Affiliation(s)
- Valentino M Gantz
- Department of Cell and Developmental Biology, University of California, La Jolla, California, USA
| | - Ethan Bier
- Department of Cell and Developmental Biology, University of California, La Jolla, California, USA
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3
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Verkuijl SAN, Ang JXD, Alphey L, Bonsall MB, Anderson MAE. The Challenges in Developing Efficient and Robust Synthetic Homing Endonuclease Gene Drives. Front Bioeng Biotechnol 2022; 10:856981. [PMID: 35419354 PMCID: PMC8996256 DOI: 10.3389/fbioe.2022.856981] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/04/2022] [Indexed: 11/13/2022] Open
Abstract
Making discrete and precise genetic changes to wild populations has been proposed as a means of addressing some of the world's most pressing ecological and public health challenges caused by insect pests. Technologies that would allow this, such as synthetic gene drives, have been under development for many decades. Recently, a new generation of programmable nucleases has dramatically accelerated technological development. CRISPR-Cas9 has improved the efficiency of genetic engineering and has been used as the principal effector nuclease in different gene drive inheritance biasing mechanisms. Of these nuclease-based gene drives, homing endonuclease gene drives have been the subject of the bulk of research efforts (particularly in insects), with many different iterations having been developed upon similar core designs. We chart the history of homing gene drive development, highlighting the emergence of challenges such as unintended repair outcomes, "leaky" expression, and parental deposition. We conclude by discussing the progress made in developing strategies to increase the efficiency of homing endonuclease gene drives and mitigate or prevent unintended outcomes.
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Affiliation(s)
- Sebald A. N. Verkuijl
- Arthropod Genetics, The Pirbright Institute, Pirbright, United Kingdom
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Joshua X. D. Ang
- Arthropod Genetics, The Pirbright Institute, Pirbright, United Kingdom
| | - Luke Alphey
- Arthropod Genetics, The Pirbright Institute, Pirbright, United Kingdom
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4
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Harami GM, Pálinkás J, Seol Y, Kovács ZJ, Gyimesi M, Harami-Papp H, Neuman KC, Kovács M. The toposiomerase IIIalpha-RMI1-RMI2 complex orients human Bloom's syndrome helicase for efficient disruption of D-loops. Nat Commun 2022; 13:654. [PMID: 35115525 PMCID: PMC8813930 DOI: 10.1038/s41467-022-28208-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 01/12/2022] [Indexed: 01/05/2023] Open
Abstract
Homologous recombination (HR) is a ubiquitous and efficient process that serves the repair of severe forms of DNA damage and the generation of genetic diversity during meiosis. HR can proceed via multiple pathways with different outcomes that may aid or impair genome stability and faithful inheritance, underscoring the importance of HR quality control. Human Bloom's syndrome (BLM, RecQ family) helicase plays central roles in HR pathway selection and quality control via unexplored molecular mechanisms. Here we show that BLM's multi-domain structural architecture supports a balance between stabilization and disruption of displacement loops (D-loops), early HR intermediates that are key targets for HR regulation. We find that this balance is markedly shifted toward efficient D-loop disruption by the presence of BLM's interaction partners Topoisomerase IIIα-RMI1-RMI2, which have been shown to be involved in multiple steps of HR-based DNA repair. Our results point to a mechanism whereby BLM can differentially process D-loops and support HR control depending on cellular regulatory mechanisms.
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Affiliation(s)
- Gábor M Harami
- ELTE-MTA "Momentum" Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117, Budapest, Hungary. .,Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA.
| | - János Pálinkás
- ELTE-MTA "Momentum" Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117, Budapest, Hungary
| | - Yeonee Seol
- Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Zoltán J Kovács
- ELTE-MTA "Momentum" Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117, Budapest, Hungary
| | - Máté Gyimesi
- ELTE-MTA "Momentum" Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117, Budapest, Hungary.,MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117, Budapest, Hungary
| | - Hajnalka Harami-Papp
- ELTE-MTA "Momentum" Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117, Budapest, Hungary.,Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Keir C Neuman
- Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Mihály Kovács
- ELTE-MTA "Momentum" Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117, Budapest, Hungary. .,MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117, Budapest, Hungary.
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5
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Abstract
Gene drives are selfish genetic elements that are transmitted to progeny at super-Mendelian (>50%) frequencies. Recently developed CRISPR-Cas9-based gene-drive systems are highly efficient in laboratory settings, offering the potential to reduce the prevalence of vector-borne diseases, crop pests and non-native invasive species. However, concerns have been raised regarding the potential unintended impacts of gene-drive systems. This Review summarizes the phenomenal progress in this field, focusing on optimal design features for full-drive elements (drives with linked Cas9 and guide RNA components) that either suppress target mosquito populations or modify them to prevent pathogen transmission, allelic drives for updating genetic elements, mitigating strategies including trans-complementing split-drives and genetic neutralizing elements, and the adaptation of drive technology to other organisms. These scientific advances, combined with ethical and social considerations, will facilitate the transparent and responsible advancement of these technologies towards field implementation.
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Affiliation(s)
- Ethan Bier
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA.
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6
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Li Z, Marcel N, Devkota S, Auradkar A, Hedrick SM, Gantz VM, Bier E. CopyCatchers are versatile active genetic elements that detect and quantify inter-homolog somatic gene conversion. Nat Commun 2021; 12:2625. [PMID: 33976171 PMCID: PMC8113449 DOI: 10.1038/s41467-021-22927-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 04/01/2021] [Indexed: 11/08/2022] Open
Abstract
CRISPR-based active genetic elements, or gene-drives, copied via homology-directed repair (HDR) in the germline, are transmitted to progeny at super-Mendelian frequencies. Active genetic elements also can generate widespread somatic mutations, but the genetic basis for such phenotypes remains uncertain. It is generally assumed that such somatic mutations are generated by non-homologous end-joining (NHEJ), the predominant double stranded break repair pathway active in somatic cells. Here, we develop CopyCatcher systems in Drosophila to detect and quantify somatic gene conversion (SGC) events. CopyCatchers inserted into two independent genetic loci reveal unexpectedly high rates of SGC in the Drosophila eye and thoracic epidermis. Focused RNAi-based genetic screens identify several unanticipated loci altering SGC efficiency, one of which (c-MYC), when downregulated, promotes SGC mediated by both plasmid and homologous chromosome-templates in human HEK293T cells. Collectively, these studies suggest that CopyCatchers can serve as effective discovery platforms to inform potential gene therapy strategies.
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Affiliation(s)
- Zhiqian Li
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | - Nimi Marcel
- Section of Molecular Biology, University of California San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | - Sushil Devkota
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | - Ankush Auradkar
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | - Stephen M Hedrick
- Section of Molecular Biology, University of California San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | - Valentino M Gantz
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | - Ethan Bier
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA.
- Tata Institute for Genetics and Society-UCSD, La Jolla, CA, USA.
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7
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The Proteomic Landscape of Centromeric Chromatin Reveals an Essential Role for the Ctf19 CCAN Complex in Meiotic Kinetochore Assembly. Curr Biol 2021; 31:283-296.e7. [PMID: 33157029 PMCID: PMC7846277 DOI: 10.1016/j.cub.2020.10.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/10/2020] [Accepted: 10/08/2020] [Indexed: 11/23/2022]
Abstract
Kinetochores direct chromosome segregation in mitosis and meiosis. Faithful gamete formation through meiosis requires that kinetochores take on new functions that impact homolog pairing, recombination, and the orientation of kinetochore attachment to microtubules in meiosis I. Using an unbiased proteomics pipeline, we determined the composition of centromeric chromatin and kinetochores at distinct cell-cycle stages, revealing extensive reorganization of kinetochores during meiosis. The data uncover a network of meiotic chromosome axis and recombination proteins that bind to centromeres in the absence of the microtubule-binding outer kinetochore sub-complexes during meiotic prophase. We show that the Ctf19cCCAN inner kinetochore complex is essential for kinetochore organization in meiosis. Our functional analyses identify a Ctf19cCCAN-dependent kinetochore assembly pathway that is dispensable for mitotic growth but becomes critical upon meiotic entry. Therefore, changes in kinetochore composition and a distinct assembly pathway specialize meiotic kinetochores for successful gametogenesis. The composition of meiotic centromeres and kinetochores is revealed Kinetochores undergo extensive changes between meiotic prophase I and metaphase I The Ctf19CCAN orchestrates meiotic kinetochore specialization A Ctf19CCAN-directed kinetochore assembly pathway is uniquely critical in meiosis
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8
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Bier E, Harrison MM, O'Connor-Giles KM, Wildonger J. Advances in Engineering the Fly Genome with the CRISPR-Cas System. Genetics 2018; 208:1-18. [PMID: 29301946 PMCID: PMC5753851 DOI: 10.1534/genetics.117.1113] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 07/08/2017] [Indexed: 12/26/2022] Open
Abstract
Drosophila has long been a premier model for the development and application of cutting-edge genetic approaches. The CRISPR-Cas system now adds the ability to manipulate the genome with ease and precision, providing a rich toolbox to interrogate relationships between genotype and phenotype, to delineate and visualize how the genome is organized, to illuminate and manipulate RNA, and to pioneer new gene drive technologies. Myriad transformative approaches have already originated from the CRISPR-Cas system, which will likely continue to spark the creation of tools with diverse applications. Here, we provide an overview of how CRISPR-Cas gene editing has revolutionized genetic analysis in Drosophila and highlight key areas for future advances.
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Affiliation(s)
- Ethan Bier
- Cell and Developmental Biology, University of California, San Diego, La Jolla, California 92093-0349
| | - Melissa M Harrison
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
| | - Kate M O'Connor-Giles
- Laboratory of Genetics and Laboratory of Cell and Molecular Biology, Wisconsin 53706
| | - Jill Wildonger
- Biochemistry Department, University of Wisconsin-Madison, Wisconsin 53706
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9
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Devlin R, Marques CA, McCulloch R. Does DNA replication direct locus-specific recombination during host immune evasion by antigenic variation in the African trypanosome? Curr Genet 2017; 63:441-449. [PMID: 27822899 PMCID: PMC5422504 DOI: 10.1007/s00294-016-0662-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 10/26/2016] [Accepted: 10/27/2016] [Indexed: 12/14/2022]
Abstract
All pathogens must survive host immune attack and, amongst the survival strategies that have evolved, antigenic variation is a particularly widespread reaction to thwart adaptive immunity. Though the reactions that underlie antigenic variation are highly varied, recombination by gene conversion is a widespread approach to immune survival in bacterial and eukaryotic pathogens. In the African trypanosome, antigenic variation involves gene conversion-catalysed movement of a huge number of variant surface glycoprotein (VSG) genes into a few telomeric sites for VSG expression, amongst which only a single site is actively transcribed at one time. Genetic evidence indicates VSG gene conversion has co-opted the general genome maintenance reaction of homologous recombination, aligning the reaction strategy with targeted rearrangements found in many organisms. What is less clear is how gene conversion might be initiated within the locality of the VSG expression sites. Here, we discuss three emerging models for VSG switching initiation and ask how these compare with processes for adaptive genome change found in other organisms.
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Affiliation(s)
- Rebecca Devlin
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Catarina A Marques
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, UK
| | - Richard McCulloch
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK.
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10
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Abstract
Meiosis, the mechanism of creating haploid gametes, is a complex cellular process observed across sexually reproducing organisms. Fundamental to meiosis is the process of homologous recombination, whereby DNA double-strand breaks are introduced into the genome and are subsequently repaired to generate either noncrossovers or crossovers. Although homologous recombination is essential for chromosome pairing during prophase I, the resulting crossovers are critical for maintaining homolog interactions and enabling accurate segregation at the first meiotic division. Thus, the placement, timing, and frequency of crossover formation must be exquisitely controlled. In this review, we discuss the proteins involved in crossover formation, the process of their formation and designation, and the rules governing crossovers, all within the context of the important landmarks of prophase I. We draw together crossover designation data across organisms, analyze their evolutionary divergence, and propose a universal model for crossover regulation.
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Affiliation(s)
- Stephen Gray
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Ithaca, New York 14853; ,
| | - Paula E Cohen
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Ithaca, New York 14853; ,
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11
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Devlin R, Marques CA, Paape D, Prorocic M, Zurita-Leal AC, Campbell SJ, Lapsley C, Dickens N, McCulloch R. Mapping replication dynamics in Trypanosoma brucei reveals a link with telomere transcription and antigenic variation. eLife 2016; 5:e12765. [PMID: 27228154 PMCID: PMC4946898 DOI: 10.7554/elife.12765] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 05/26/2016] [Indexed: 01/14/2023] Open
Abstract
Survival of Trypanosoma brucei depends upon switches in its protective Variant Surface Glycoprotein (VSG) coat by antigenic variation. VSG switching occurs by frequent homologous recombination, which is thought to require locus-specific initiation. Here, we show that a RecQ helicase, RECQ2, acts to repair DNA breaks, including in the telomeric site of VSG expression. Despite this, RECQ2 loss does not impair antigenic variation, but causes increased VSG switching by recombination, arguing against models for VSG switch initiation through direct generation of a DNA double strand break (DSB). Indeed, we show DSBs inefficiently direct recombination in the VSG expression site. By mapping genome replication dynamics, we reveal that the transcribed VSG expression site is the only telomeric site that is early replicating - a differential timing only seen in mammal-infective parasites. Specific association between VSG transcription and replication timing reveals a model for antigenic variation based on replication-derived DNA fragility.
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Affiliation(s)
- Rebecca Devlin
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Catarina A Marques
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Daniel Paape
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Marko Prorocic
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Andrea C Zurita-Leal
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Samantha J Campbell
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Craig Lapsley
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Nicholas Dickens
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Richard McCulloch
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
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12
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Jagut M, Hamminger P, Woglar A, Millonigg S, Paulin L, Mikl M, Dello Stritto MR, Tang L, Habacher C, Tam A, Gallach M, von Haeseler A, Villeneuve AM, Jantsch V. Separable Roles for a Caenorhabditis elegans RMI1 Homolog in Promoting and Antagonizing Meiotic Crossovers Ensure Faithful Chromosome Inheritance. PLoS Biol 2016; 14:e1002412. [PMID: 27011106 PMCID: PMC4807110 DOI: 10.1371/journal.pbio.1002412] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 02/19/2016] [Indexed: 11/30/2022] Open
Abstract
During the first meiotic division, crossovers (COs) between homologous chromosomes ensure their correct segregation. COs are produced by homologous recombination (HR)-mediated repair of programmed DNA double strand breaks (DSBs). As more DSBs are induced than COs, mechanisms are required to establish a regulated number of COs and to repair remaining intermediates as non-crossovers (NCOs). We show that the Caenorhabditis elegans RMI1 homolog-1 (RMH-1) functions during meiosis to promote both CO and NCO HR at appropriate chromosomal sites. RMH-1 accumulates at CO sites, dependent on known pro-CO factors, and acts to promote CO designation and enforce the CO outcome of HR-intermediate resolution. RMH-1 also localizes at NCO sites and functions in parallel with SMC-5 to antagonize excess HR-based connections between chromosomes. Moreover, RMH-1 also has a major role in channeling DSBs into an NCO HR outcome near the centers of chromosomes, thereby ensuring that COs form predominantly at off-center positions. A nematode homolog of the conserved DNA repair factor RMI1 plays multiple genetically separable roles that together ensure the faithful inheritance of intact genomes during sexual reproduction. During meiosis, faithful separation of chromosomes into gametes is essential for fertility and healthy progeny. During the first meiotic division, crossovers (CO) between parental homologs ensure their correct segregation. Programmed DNA double strand breaks (DSBs) and resection steps generate single-stranded overhangs that invade a sister chromatid of the homolog to initiate homologous recombination. This culminates in the generation of a DNA double Holliday junction (dHJ). This can be acted upon by resolvases to produce CO and non-crossover (NCO) products, depending on where the resolvases cut the DNA. Alternatively, NCOs can also be produced by decatenation via the RecQ helicase–topoisomeraseIII–Rmi1 (RTR) complex. The mammalian RTR contains a topoisomerase, Bloom’s helicase, and RMI1/2 scaffolding components. It disassembles dHJs in vitro and contributes the major NCO activity in mitosis. Here, we provide evidence that the Caenorhabditis elegans RMH-1 functions in distinct complexes during meiosis to produce both COs and NCOs in an in vivo animal model system. Strikingly, RMH-1 spatially regulates the distribution of COs on chromosomes, demonstrating that the RTR complex can act locally within specific chromosome domains.
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Affiliation(s)
- Marlène Jagut
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Patricia Hamminger
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Alexander Woglar
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Sophia Millonigg
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Luis Paulin
- Center for Integrative Bioinformatics Vienna (CIBIV), Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Martin Mikl
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Maria Rosaria Dello Stritto
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Lois Tang
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Cornelia Habacher
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
| | - Angela Tam
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Miguel Gallach
- Center for Integrative Bioinformatics Vienna (CIBIV), Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Arndt von Haeseler
- Center for Integrative Bioinformatics Vienna (CIBIV), Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna and Medical University of Vienna, Vienna, Austria
- Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Austria
| | - Anne M. Villeneuve
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Verena Jantsch
- Department of Chromosome Biology, Max F. Perutz Laboratories, Vienna Bio Center, University of Vienna, Vienna, Austria
- * E-mail:
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Poot M. Chromothripsis after Stumbling through DNA Replication. Mol Syndromol 2016; 6:207-9. [PMID: 26997940 DOI: 10.1159/000441081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2015] [Indexed: 11/19/2022] Open
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14
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Poot M, Haaf T. Mechanisms of Origin, Phenotypic Effects and Diagnostic Implications of Complex Chromosome Rearrangements. Mol Syndromol 2015; 6:110-34. [PMID: 26732513 DOI: 10.1159/000438812] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2015] [Indexed: 01/08/2023] Open
Abstract
Complex chromosome rearrangements (CCRs) are currently defined as structural genome variations that involve more than 2 chromosome breaks and result in exchanges of chromosomal segments. They are thought to be extremely rare, but their detection rate is rising because of improvements in molecular cytogenetic technology. Their population frequency is also underestimated, since many CCRs may not elicit a phenotypic effect. CCRs may be the result of fork stalling and template switching, microhomology-mediated break-induced repair, breakage-fusion-bridge cycles, or chromothripsis. Patients with chromosomal instability syndromes show elevated rates of CCRs due to impaired DNA double-strand break responses during meiosis. Therefore, the putative functions of the proteins encoded by ATM, BLM, WRN, ATR, MRE11, NBS1, and RAD51 in preventing CCRs are discussed. CCRs may exert a pathogenic effect by either (1) gene dosage-dependent mechanisms, e.g. haploinsufficiency, (2) mechanisms based on disruption of the genomic architecture, such that genes, parts of genes or regulatory elements are truncated, fused or relocated and thus their interactions disturbed - these mechanisms will predominantly affect gene expression - or (3) mixed mutation mechanisms in which a CCR on one chromosome is combined with a different type of mutation on the other chromosome. Such inferred mechanisms of pathogenicity need corroboration by mRNA sequencing. Also, future studies with in vitro models, such as inducible pluripotent stem cells from patients with CCRs, and transgenic model organisms should substantiate current inferences regarding putative pathogenic effects of CCRs. The ramifications of the growing body of information on CCRs for clinical and experimental genetics and future treatment modalities are briefly illustrated with 2 cases, one of which suggests KDM4C (JMJD2C) as a novel candidate gene for mental retardation.
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Affiliation(s)
- Martin Poot
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Thomas Haaf
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
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