1
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Zong X, Lou Y, Xia M, Zhao K, Chen J, Huang J, Yang S, Wang L. Recombination and repeat-induced point mutation landscapes reveal trade-offs between the sexual and asexual cycles of Magnaporthe oryzae. J Genet Genomics 2024; 51:723-734. [PMID: 38490361 DOI: 10.1016/j.jgg.2024.03.003] [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: 01/30/2024] [Revised: 03/01/2024] [Accepted: 03/06/2024] [Indexed: 03/17/2024]
Abstract
The fungal disease caused by Magnaporthe oryzae is one of the most devastating diseases that endanger many crops worldwide. Evidence shows that sexual reproduction can be advantageous for fungal diseases as hybridization facilitates host-jumping. However, the pervasive clonal lineages of M. oryzae observed in natural fields contradict this expectation. A better understanding of the roles of recombination and the fungi-specific repeat-induced point mutation (RIP) in shaping its evolutionary trajectory is essential to bridge this knowledge gap. Here we systematically investigate the RIP and recombination landscapes in M. oryzae using a whole genome sequencing data from 252 population samples and 92 cross progenies. Our data reveal that the RIP can robustly capture the population history of M. oryzae, and we provide accurate estimations of the recombination and RIP rates across different M. oryzae clades. Significantly, our results highlight a parent-of-origin bias in both recombination and RIP rates, tightly associating with their sexual potential and variations of effector proteins. This bias suggests a critical trade-off between generating novel allelic combinations in the sexual cycle to facilitate host-jumping and stimulating transposon-associated diversification of effectors in the asexual cycle to facilitate host coevolution. These findings provide unique insights into understanding the evolution of blast fungus.
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Affiliation(s)
- Xifang Zong
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210000, China
| | - Yaxin Lou
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210000, China
| | - Mengshuang Xia
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210000, China
| | - Kunyang Zhao
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210000, China
| | - Jingxuan Chen
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210000, China
| | - Ju Huang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Bioinformatics Center, Academy for Advanced Interdisciplinary Studies, Nanjing Agricultural University, Nanjing, Jiangsu 210000, China
| | - Sihai Yang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210000, China; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210000, China.
| | - Long Wang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210000, China.
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2
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Wang W, Zhang X, Garcia S, Leitch AR, Kovařík A. Intragenomic rDNA variation - the product of concerted evolution, mutation, or something in between? Heredity (Edinb) 2023; 131:179-188. [PMID: 37402824 PMCID: PMC10462631 DOI: 10.1038/s41437-023-00634-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 06/12/2023] [Accepted: 06/12/2023] [Indexed: 07/06/2023] Open
Abstract
The classical model of concerted evolution states that hundreds to thousands of ribosomal DNA (rDNA) units undergo homogenization, making the multiple copies of the individual units more uniform across the genome than would be expected given mutation frequencies and gene redundancy. While the universality of this over 50-year-old model has been confirmed in a range of organisms, advanced high throughput sequencing techniques have also revealed that rDNA homogenization in many organisms is partial and, in rare cases, even apparently failing. The potential underpinning processes leading to unexpected intragenomic variation have been discussed in a number of studies, but a comprehensive understanding remains to be determined. In this work, we summarize information on variation or polymorphisms in rDNAs across a wide range of taxa amongst animals, fungi, plants, and protists. We discuss the definition and description of concerted evolution and describe whether incomplete concerted evolution of rDNAs predominantly affects coding or non-coding regions of rDNA units and if it leads to the formation of pseudogenes or not. We also discuss the factors contributing to rDNA variation, such as interspecific hybridization, meiotic cycles, rDNA expression status, genome size, and the activity of effector genes involved in genetic recombination, epigenetic modifications, and DNA editing. Finally, we argue that a combination of approaches is needed to target genetic and epigenetic phenomena influencing incomplete concerted evolution, to give a comprehensive understanding of the evolution and functional consequences of intragenomic variation in rDNA.
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Affiliation(s)
- Wencai Wang
- Science and Technology Innovation Center, Guangzhou University of Chinese Medicine, Guangzhou, 510405, China
| | - Xianzhi Zhang
- Department of Horticulture, College of Horticulture and Landscape Architecture, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Sònia Garcia
- Institut Botànic de Barcelona, IBB (CSIC - Ajuntament de Barcelona), Barcelona, Spain
| | - Andrew R Leitch
- School of Biological and Behavioral Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Aleš Kovařík
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, CZ-61200, Czech Republic.
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3
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Ma C, Liu J, Tang J, Sun Y, Jiang X, Zhang T, Feng Y, Liu Q, Wang L. Current genetic strategies to investigate gene functions in Trichoderma reesei. Microb Cell Fact 2023; 22:97. [PMID: 37161391 PMCID: PMC10170752 DOI: 10.1186/s12934-023-02104-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 04/21/2023] [Indexed: 05/11/2023] Open
Abstract
The filamentous fungus Trichoderma reesei (teleomorph Hypocrea jecorina, Ascomycota) is a well-known lignocellulolytic enzymes-producing strain in industry. To increase the fermentation titer of lignocellulolytic enzymes, random mutagenesis and rational genetic engineering in T. reesei were carried out since it was initially found in the Solomon Islands during the Second World War. Especially the continuous exploration of the underlying regulatory network during (hemi)cellulase gene expression in the post-genome era provided various strategies to develop an efficient fungal cell factory for these enzymes' production. Meanwhile, T. reesei emerges competitiveness potential as a filamentous fungal chassis to produce proteins from other species (e.g., human albumin and interferon α-2b, SARS-CoV-2 N antigen) in virtue of the excellent expression and secretion system acquired during the studies about (hemi)cellulase production. However, all the achievements in high yield of (hemi)cellulases are impossible to finish without high-efficiency genetic strategies to analyze the proper functions of those genes involved in (hemi)cellulase gene expression or secretion. Here, we in detail summarize the current strategies employed to investigate gene functions in T. reesei. These strategies are supposed to be beneficial for extending the potential of T. reesei in prospective strain engineering.
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Affiliation(s)
- Chixiang Ma
- China Medical University-The Queen's University of Belfast Joint College, Shenyang, Liaoning, 110122, China
| | - Jialong Liu
- College of Basic Medical Sciences, Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Jiaxin Tang
- College of Basic Medical Sciences, Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Yuanlu Sun
- China Medical University-The Queen's University of Belfast Joint College, Shenyang, Liaoning, 110122, China
| | - Xiaojie Jiang
- China Medical University-The Queen's University of Belfast Joint College, Shenyang, Liaoning, 110122, China
| | - Tongtong Zhang
- China Medical University-The Queen's University of Belfast Joint College, Shenyang, Liaoning, 110122, China
| | - Yan Feng
- College of Life Sciences, Shanxi Agricultural University, Jinzhong, 030801, Shanxi, China
| | - Qinghua Liu
- College of Basic Medical Sciences, Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Lei Wang
- College of Basic Medical Sciences, Shanxi Medical University, Taiyuan, 030001, Shanxi, China.
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4
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Feurtey A, Lorrain C, McDonald MC, Milgate A, Solomon PS, Warren R, Puccetti G, Scalliet G, Torriani SFF, Gout L, Marcel TC, Suffert F, Alassimone J, Lipzen A, Yoshinaga Y, Daum C, Barry K, Grigoriev IV, Goodwin SB, Genissel A, Seidl MF, Stukenbrock EH, Lebrun MH, Kema GHJ, McDonald BA, Croll D. A thousand-genome panel retraces the global spread and adaptation of a major fungal crop pathogen. Nat Commun 2023; 14:1059. [PMID: 36828814 PMCID: PMC9958100 DOI: 10.1038/s41467-023-36674-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 02/10/2023] [Indexed: 02/26/2023] Open
Abstract
Human activity impacts the evolutionary trajectories of many species worldwide. Global trade of agricultural goods contributes to the dispersal of pathogens reshaping their genetic makeup and providing opportunities for virulence gains. Understanding how pathogens surmount control strategies and cope with new climates is crucial to predicting the future impact of crop pathogens. Here, we address this by assembling a global thousand-genome panel of Zymoseptoria tritici, a major fungal pathogen of wheat reported in all production areas worldwide. We identify the global invasion routes and ongoing genetic exchange of the pathogen among wheat-growing regions. We find that the global expansion was accompanied by increased activity of transposable elements and weakened genomic defenses. Finally, we find significant standing variation for adaptation to new climates encountered during the global spread. Our work shows how large population genomic panels enable deep insights into the evolutionary trajectory of a major crop pathogen.
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Affiliation(s)
- Alice Feurtey
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
- Plant Pathology, D-USYS, ETH Zurich, CH-8092, Zurich, Switzerland
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Cécile Lorrain
- Plant Pathology, D-USYS, ETH Zurich, CH-8092, Zurich, Switzerland
| | - Megan C McDonald
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT, Australia
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Andrew Milgate
- NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Pine Gully Road, Wagga Wagga, NSW, 2650, Australia
| | - Peter S Solomon
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Rachael Warren
- The New Zealand Institute for Plant and Food Research Limited, Lincoln, New Zealand
| | - Guido Puccetti
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
- Syngenta Crop Protection AG, CH-4332, Stein, Switzerland
| | | | | | - Lilian Gout
- Université Paris Saclay, INRAE, UR BIOGER, 91120, Palaiseau, France
| | - Thierry C Marcel
- Université Paris Saclay, INRAE, UR BIOGER, 91120, Palaiseau, France
| | - Frédéric Suffert
- Université Paris Saclay, INRAE, UR BIOGER, 91120, Palaiseau, France
| | | | - Anna Lipzen
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yuko Yoshinaga
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Christopher Daum
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Kerrie Barry
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Igor V Grigoriev
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, 9472, USA
| | | | - Anne Genissel
- Université Paris Saclay, INRAE, UR BIOGER, 91120, Palaiseau, France
| | - Michael F Seidl
- Wageningen University and Research, Laboratory of Phytopathology, Wageningen, The Netherlands
- Utrecht University, Theoretical Biology and Bioinformatics, Utrecht, The Netherlands
| | - Eva H Stukenbrock
- Max Planck Institute for Evolutionary Biology, Plön, Germany
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany
| | | | - Gert H J Kema
- Wageningen University and Research, Laboratory of Phytopathology, Wageningen, The Netherlands
| | - Bruce A McDonald
- Plant Pathology, D-USYS, ETH Zurich, CH-8092, Zurich, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland.
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5
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DNA Methyltransferases and DNA Damage. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1389:349-361. [DOI: 10.1007/978-3-031-11454-0_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Asanuma T, Inagaki S, Kakutani T, Aburatani H, Murakami Y. Tandemly repeated genes promote RNAi-mediated heterochromatin formation via an antisilencing factor, Epe1, in fission yeast. Genes Dev 2022; 36:1145-1159. [PMID: 36617881 PMCID: PMC9851402 DOI: 10.1101/gad.350129.122] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022]
Abstract
In most eukaryotes, constitutive heterochromatin, defined by histone H3 lysine 9 methylation (H3K9me), is enriched on repetitive DNA, such as pericentromeric repeats and transposons. Furthermore, repetitive transgenes also induce heterochromatin formation in diverse model organisms. However, the mechanisms that promote heterochromatin formation at repetitive DNA elements are still not clear. Here, using fission yeast, we show that tandemly repeated mRNA genes promote RNA interference (RNAi)-mediated heterochromatin formation in cooperation with an antisilencing factor, Epe1. Although the presence of tandemly repeated genes itself does not cause heterochromatin formation, once complementary small RNAs are artificially supplied in trans, the RNAi machinery assembled on the repeated genes starts producing cognate small RNAs in cis to autonomously maintain heterochromatin at these sites. This "repeat-induced RNAi" depends on the copy number of repeated genes and Epe1, which is known to remove H3K9me and derepress the transcription of genes underlying heterochromatin. Analogous to repeated genes, the DNA sequence underlying constitutive heterochromatin encodes widespread transcription start sites (TSSs), from which Epe1 activates ncRNA transcription to promote RNAi-mediated heterochromatin formation. Our results suggest that when repetitive transcription units underlie heterochromatin, Epe1 generates sufficient transcripts for the activation of RNAi without disruption of heterochromatin.
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Affiliation(s)
- Takahiro Asanuma
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Soichi Inagaki
- Department of Biological Sciences, Faculty of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Tetsuji Kakutani
- Department of Biological Sciences, Faculty of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Hiroyuki Aburatani
- Genome Science Division, Research Center for Advanced Science and Technology, University of Tokyo, Tokyo 153-8904, Japan
| | - Yota Murakami
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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7
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Carlier F, Nguyen TS, Mazur AK, Gladyshev E. Modulation of C-to-T mutation by recombination-independent pairing of closely positioned DNA repeats. Biophys J 2021; 120:4325-4336. [PMID: 34509507 DOI: 10.1016/j.bpj.2021.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 08/14/2021] [Accepted: 09/07/2021] [Indexed: 11/29/2022] Open
Abstract
Repeat-induced point mutation is a genetic process that creates cytosine-to-thymine (C-to-T) transitions in duplicated genomic sequences in fungi. Repeat-induced point mutation detects duplications (irrespective of their origin, specific sequence, coding capacity, and genomic positions) by a recombination-independent mechanism that likely matches intact DNA double helices directly, without relying on the annealing of complementary single strands. In the fungus Neurospora crassa, closely positioned repeats can induce mutation of the adjoining nonrepetitive regions. This process is related to heterochromatin assembly and requires the cytosine methyltransferase DIM-2. Using DIM-2-dependent mutation as a readout of homologous pairing, we find that GC-rich repeats produce a much stronger response than AT-rich repeats, independently of their intrinsic propensity to become mutated. We also report that direct repeats trigger much stronger DIM-2-dependent mutation than inverted repeats. These results can be rationalized in the light of a recently proposed model of homologous DNA pairing, in which DNA double helices associate by forming sequence-specific quadruplex-based contacts with a concomitant release of supercoiling. A similar process featuring pairing-induced supercoiling may initiate epigenetic silencing of repetitive DNA in other organisms, including humans.
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Affiliation(s)
- Florian Carlier
- Group "Fungal Epigenomics", Department of Mycology, Institut Pasteur, Paris, France
| | - Tinh-Suong Nguyen
- Group "Fungal Epigenomics", Department of Mycology, Institut Pasteur, Paris, France
| | - Alexey K Mazur
- Group "Fungal Epigenomics", Department of Mycology, Institut Pasteur, Paris, France; CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, Paris, France.
| | - Eugene Gladyshev
- Group "Fungal Epigenomics", Department of Mycology, Institut Pasteur, Paris, France.
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8
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Recombination-independent recognition of DNA homology for meiotic silencing in Neurospora crassa. Proc Natl Acad Sci U S A 2021; 118:2108664118. [PMID: 34385329 DOI: 10.1073/pnas.2108664118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The pairing of homologous chromosomes represents a critical step of meiosis in nearly all sexually reproducing species. In many organisms, pairing involves chromosomes that remain apparently intact. The mechanistic nature of homology recognition at the basis of such pairing is unknown. Using "meiotic silencing by unpaired DNA" (MSUD) as a model process, we demonstrate the existence of a cardinally different approach to DNA homology recognition in meiosis. The main advantage of MSUD over other experimental systems lies in its ability to identify any relatively short DNA fragment lacking a homologous allelic partner. Here, we show that MSUD does not rely on the canonical mechanism of meiotic recombination, yet it is promoted by REC8, a conserved component of the meiotic cohesion complex. We also show that certain patterns of interspersed homology are recognized as pairable during MSUD. Such patterns need to be colinear and must contain short tracts of sequence identity spaced apart at 21 or 22 base pairs. By using these periodicity values as a guiding parameter in all-atom molecular modeling, we discover that homologous DNA molecules can pair by forming quadruplex-based contacts with an interval of 2.5 helical turns. This process requires right-handed plectonemic coiling and additional conformational changes in the intervening double-helical segments. Our results 1) reconcile genetic and biophysical evidence for the existence of direct homologous double-stranded DNA (dsDNA)-dsDNA pairing, 2) identify a role for this process in initiating RNA interference, and 3) suggest that chromosomes can be cross-matched by a precise mechanism that operates on intact dsDNA molecules.
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9
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Lorrain C, Feurtey A, Möller M, Haueisen J, Stukenbrock E. Dynamics of transposable elements in recently diverged fungal pathogens: lineage-specific transposable element content and efficiency of genome defenses. G3-GENES GENOMES GENETICS 2021; 11:6173990. [PMID: 33724368 PMCID: PMC8759822 DOI: 10.1093/g3journal/jkab068] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/19/2021] [Indexed: 01/29/2023]
Abstract
Transposable elements (TEs) impact genome plasticity, architecture, and evolution in fungal plant pathogens. The wide range of TE content observed in fungal genomes reflects diverse efficacy of host-genome defense mechanisms that can counter-balance TE expansion and spread. Closely related species can harbor drastically different TE repertoires. The evolution of fungal effectors, which are crucial determinants of pathogenicity, has been linked to the activity of TEs in pathogen genomes. Here, we describe how TEs have shaped genome evolution of the fungal wheat pathogen Zymoseptoria tritici and four closely related species. We compared de novo TE annotations and repeat-induced point mutation signatures in 26 genomes from the Zymoseptoria species-complex. Then, we assessed the relative insertion ages of TEs using a comparative genomics approach. Finally, we explored the impact of TE insertions on genome architecture and plasticity. The 26 genomes of Zymoseptoria species reflect different TE dynamics with a majority of recent insertions. TEs associate with accessory genome compartments, with chromosomal rearrangements, with gene presence/absence variation, and with effectors in all Zymoseptoria species. We find that the extent of RIP-like signatures varies among Z. tritici genomes compared to genomes of the sister species. The detection of a reduction of RIP-like signatures and TE recent insertions in Z. tritici reflects ongoing but still moderate TE mobility.
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Affiliation(s)
- Cécile Lorrain
- Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön 24306, Germany.,Environmental Genomics, Christian-Albrechts University of Kiel, Kiel 24118, Germany.,Université de Lorraine/INRAE, UMR 1136 Interactions Arbres/Microorganismes, INRAE Centre Grand Est-Nancy, Champenoux 54280, France
| | - Alice Feurtey
- Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön 24306, Germany.,Environmental Genomics, Christian-Albrechts University of Kiel, Kiel 24118, Germany
| | - Mareike Möller
- Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön 24306, Germany.,Environmental Genomics, Christian-Albrechts University of Kiel, Kiel 24118, Germany
| | - Janine Haueisen
- Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön 24306, Germany.,Environmental Genomics, Christian-Albrechts University of Kiel, Kiel 24118, Germany
| | - Eva Stukenbrock
- Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön 24306, Germany.,Environmental Genomics, Christian-Albrechts University of Kiel, Kiel 24118, Germany
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10
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Möller M, Habig M, Lorrain C, Feurtey A, Haueisen J, Fagundes WC, Alizadeh A, Freitag M, Stukenbrock EH. Recent loss of the Dim2 DNA methyltransferase decreases mutation rate in repeats and changes evolutionary trajectory in a fungal pathogen. PLoS Genet 2021; 17:e1009448. [PMID: 33750960 PMCID: PMC8016269 DOI: 10.1371/journal.pgen.1009448] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 04/01/2021] [Accepted: 02/26/2021] [Indexed: 01/04/2023] Open
Abstract
DNA methylation is found throughout all domains of life, yet the extent and function of DNA methylation differ among eukaryotes. Strains of the plant pathogenic fungus Zymoseptoria tritici appeared to lack cytosine DNA methylation (5mC) because gene amplification followed by Repeat-Induced Point mutation (RIP) resulted in the inactivation of the dim2 DNA methyltransferase gene. 5mC is, however, present in closely related sister species. We demonstrate that inactivation of dim2 occurred recently as some Z. tritici isolates carry a functional dim2 gene. Moreover, we show that dim2 inactivation occurred by a different path than previously hypothesized. We mapped the genome-wide distribution of 5mC in strains with or without functional dim2 alleles. Presence of functional dim2 correlates with high levels of 5mC in transposable elements (TEs), suggesting a role in genome defense. We identified low levels of 5mC in strains carrying non-functional dim2 alleles, suggesting that 5mC is maintained over time, presumably by an active Dnmt5 DNA methyltransferase. Integration of a functional dim2 allele in strains with mutated dim2 restored normal 5mC levels, demonstrating de novo cytosine methylation activity of Dim2. To assess the importance of 5mC for genome evolution, we performed an evolution experiment, comparing genomes of strains with high levels of 5mC to genomes of strains lacking functional dim2. We found that presence of a functional dim2 allele alters nucleotide composition by promoting C to T transitions (C→T) specifically at CpA (CA) sites during mitosis, likely contributing to TE inactivation. Our results show that 5mC density at TEs is a polymorphic trait in Z. tritici populations that can impact genome evolution.
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Affiliation(s)
- Mareike Möller
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Michael Habig
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Cécile Lorrain
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Alice Feurtey
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Janine Haueisen
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Wagner C. Fagundes
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Alireza Alizadeh
- Department of Plant Protection, Faculty of Agriculture, Azarbaijan Shahid Madani University, Tabriz, Iran
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States of America
| | - Eva H. Stukenbrock
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
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11
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Crickard JB, Moevus CJ, Kwon Y, Sung P, Greene EC. Rad54 Drives ATP Hydrolysis-Dependent DNA Sequence Alignment during Homologous Recombination. Cell 2020; 181:1380-1394.e18. [PMID: 32502392 DOI: 10.1016/j.cell.2020.04.056] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 03/07/2020] [Accepted: 04/29/2020] [Indexed: 12/30/2022]
Abstract
Homologous recombination (HR) helps maintain genome integrity, and HR defects give rise to disease, especially cancer. During HR, damaged DNA must be aligned with an undamaged template through a process referred to as the homology search. Despite decades of study, key aspects of this search remain undefined. Here, we use single-molecule imaging to demonstrate that Rad54, a conserved Snf2-like protein found in all eukaryotes, switches the search from the diffusion-based pathways characteristic of the basal HR machinery to an active process in which DNA sequences are aligned via an ATP-dependent molecular motor-driven mechanism. We further demonstrate that Rad54 disrupts the donor template strands, enabling the search to take place within a migrating DNA bubble-like structure that is bound by replication protein A (RPA). Our results reveal that Rad54, working together with RPA, fundamentally alters how DNA sequences are aligned during HR.
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Affiliation(s)
- J Brooks Crickard
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Corentin J Moevus
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Youngho Kwon
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Patrick Sung
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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12
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da Silva LL, Moreno HLA, Correia HLN, Santana MF, de Queiroz MV. Colletotrichum: species complexes, lifestyle, and peculiarities of some sources of genetic variability. Appl Microbiol Biotechnol 2020; 104:1891-1904. [PMID: 31932894 DOI: 10.1007/s00253-020-10363-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/30/2019] [Accepted: 01/09/2020] [Indexed: 11/25/2022]
Abstract
The genus Colletotrichum comprises species with different lifestyles but is mainly known for phytopathogenic species that infect crops of agronomic relevance causing considerable losses. The fungi of the genus Colletotrichum are distributed in species complexes and within each complex some species have particularities regarding their lifestyle. The most commonly found and described lifestyles in Colletotrichum are endophytic and hemibiotrophic phytopathogenic. Several of these phytopathogenic species show wide genetic variability, which makes long-term maintenance of resistance in plants difficult. Different mechanisms may play an important role in the emergence of genetic variants but are not yet fully understood in this genus. These mechanisms include heterokaryosis, a parasexual cycle, sexual cycle, transposable element activity, and repeat-induced point mutations. This review provides an overview of the genus Colletotrichum, the species complexes described so far and the most common lifestyles in the genus, with a special emphasis on the mechanisms that may be responsible, at least in part, for the emergence of new genotypes under field conditions.
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Affiliation(s)
- Leandro Lopes da Silva
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Hanna Lorena Alvarado Moreno
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Hilberty Lucas Nunes Correia
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Mateus Ferreira Santana
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Marisa Vieira de Queiroz
- Laboratório de Genética Molecular de Fungos, Departamento de Microbiologia/Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG, Brazil.
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13
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Nguyen TS, Gladyshev E. Developing a tetO/TetR system in Neurospora crassa. Fungal Genet Biol 2019; 136:103316. [PMID: 31821884 DOI: 10.1016/j.fgb.2019.103316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 11/30/2019] [Accepted: 12/04/2019] [Indexed: 10/25/2022]
Abstract
The development of a tetO/TetR system in the fungus Neurospora crassa is described. The system includes (i) a synthetic gene encoding a TetR variant fused to GFP, and (ii) a standard tetO array integrated homologously, as a proof of principle, near the his-3 gene. The localization of TetR-GFP at the tetO array (observed by fluorescence microscopy) can be disrupted by the application of tetracycline. The full-length array is stable during vegetative growth, but it triggers strong repeat-induced point mutation (RIP) by the RID-dependent as well as the DIM-2-dependent pathways during the sexual phase. Thus, both RIP pathways must be inactivated to allow the faithful inheritance of the unmodified construct. In summary, this study introduces a new molecular tool into Neurospora research, and suggests that the standard tetO array can self-engage in recombination-independent homologous pairing.
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Affiliation(s)
- Tinh-Suong Nguyen
- Group Fungal Epigenomics, Department of Mycology, Institut Pasteur, Paris 75015, France
| | - Eugene Gladyshev
- Group Fungal Epigenomics, Department of Mycology, Institut Pasteur, Paris 75015, France.
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14
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Mazur AK, Nguyen TS, Gladyshev E. Direct Homologous dsDNA-dsDNA Pairing: How, Where, and Why? J Mol Biol 2019; 432:737-744. [PMID: 31726060 DOI: 10.1016/j.jmb.2019.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/22/2019] [Accepted: 11/05/2019] [Indexed: 10/25/2022]
Abstract
The ability of homologous chromosomes (or selected chromosomal loci) to pair specifically in the apparent absence of DNA breakage and recombination represents a prominent feature of eukaryotic biology. The mechanism of homology recognition at the basis of such recombination-independent pairing has remained elusive. A number of studies have supported the idea that sequence homology can be sensed between intact DNA double helices in vivo. In particular, recent analyses of the two silencing phenomena in fungi, known as "repeat-induced point mutation" (RIP) and "meiotic silencing by unpaired DNA" (MSUD), have provided genetic evidence for the existence of the direct homologous dsDNA-dsDNA pairing. Both RIP and MSUD likely rely on the same search strategy, by which dsDNA segments are matched as arrays of interspersed base-pair triplets. This process is general and very efficient, yet it proceeds normally without the RecA/Rad51/Dmc1 proteins. Further studies of RIP and MSUD may yield surprising insights into the function of DNA in the cell.
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Affiliation(s)
- Alexey K Mazur
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, 13 Rue Pierre et Marie Curie, F-75005 Paris, France; Group Fungal Epigenomics, Department of Mycology, Institut Pasteur, Paris 75015, France; Institut de Biologie Physico-Chimique-Fondation Edmond de Rothschild, PSL Research University, Paris, France
| | - Tinh-Suong Nguyen
- Group Fungal Epigenomics, Department of Mycology, Institut Pasteur, Paris 75015, France
| | - Eugene Gladyshev
- Group Fungal Epigenomics, Department of Mycology, Institut Pasteur, Paris 75015, France.
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15
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Schmitz RJ, Lewis ZA, Goll MG. DNA Methylation: Shared and Divergent Features across Eukaryotes. Trends Genet 2019; 35:818-827. [PMID: 31399242 DOI: 10.1016/j.tig.2019.07.007] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/01/2019] [Accepted: 07/15/2019] [Indexed: 02/02/2023]
Abstract
Chemical modification of nucleotide bases in DNA provides one mechanism for conveying information in addition to the genetic code. 5-methylcytosine (5mC) represents the most common chemically modified base in eukaryotic genomes. Sometimes referred to simply as DNA methylation, in eukaryotes 5mC is most prevalent at CpG dinucleotides and is frequently associated with transcriptional repression of transposable elements. However, 5mC levels and distributions are variable across phylogenies, and emerging evidence suggests that the functions of DNA methylation may be more diverse and complex than was previously appreciated. We summarize the current understanding of DNA methylation profiles and functions in different eukaryotic lineages.
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Affiliation(s)
- Robert J Schmitz
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Zachary A Lewis
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Mary G Goll
- Department of Genetics, University of Georgia, Athens, GA 30602, USA.
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16
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Grognet P, Timpano H, Carlier F, Aït-Benkhali J, Berteaux-Lecellier V, Debuchy R, Bidard F, Malagnac F. A RID-like putative cytosine methyltransferase homologue controls sexual development in the fungus Podospora anserina. PLoS Genet 2019; 15:e1008086. [PMID: 31412020 PMCID: PMC6709928 DOI: 10.1371/journal.pgen.1008086] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/26/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022] Open
Abstract
DNA methyltransferases are ubiquitous enzymes conserved in bacteria, plants and opisthokonta. These enzymes, which methylate cytosines, are involved in numerous biological processes, notably development. In mammals and higher plants, methylation patterns established and maintained by the cytosine DNA methyltransferases (DMTs) are essential to zygotic development. In fungi, some members of an extensively conserved fungal-specific DNA methyltransferase class are both mediators of the Repeat Induced Point mutation (RIP) genome defense system and key players of sexual reproduction. Yet, no DNA methyltransferase activity of these purified RID (RIP deficient) proteins could be detected in vitro. These observations led us to explore how RID-like DNA methyltransferase encoding genes would play a role during sexual development of fungi showing very little genomic DNA methylation, if any. To do so, we used the model ascomycete fungus Podospora anserina. We identified the PaRid gene, encoding a RID-like DNA methyltransferase and constructed knocked-out ΔPaRid defective mutants. Crosses involving P. anserina ΔPaRid mutants are sterile. Our results show that, although gametes are readily formed and fertilization occurs in a ΔPaRid background, sexual development is blocked just before the individualization of the dikaryotic cells leading to meiocytes. Complementation of ΔPaRid mutants with ectopic alleles of PaRid, including GFP-tagged, point-mutated and chimeric alleles, demonstrated that the catalytic motif of the putative PaRid methyltransferase is essential to ensure proper sexual development and that the expression of PaRid is spatially and temporally restricted. A transcriptomic analysis performed on mutant crosses revealed an overlap of the PaRid-controlled genetic network with the well-known mating-types gene developmental pathway common to an important group of fungi, the Pezizomycotina.
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Affiliation(s)
- Pierre Grognet
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris‐Saclay, France
| | - Hélène Timpano
- Université Paris-Sud, Institut de Génétique et Microbiologie UMR8621, Orsay, France, CNRS, Institut de Génétique et Microbiologie UMR8621, Orsay, France
| | - Florian Carlier
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris‐Saclay, France
| | - Jinane Aït-Benkhali
- Université Paris-Sud, Institut de Génétique et Microbiologie UMR8621, Orsay, France, CNRS, Institut de Génétique et Microbiologie UMR8621, Orsay, France
| | | | - Robert Debuchy
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris‐Saclay, France
| | - Frédérique Bidard
- Université Paris-Sud, Institut de Génétique et Microbiologie UMR8621, Orsay, France, CNRS, Institut de Génétique et Microbiologie UMR8621, Orsay, France
| | - Fabienne Malagnac
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris‐Saclay, France
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Kim S, Dunham MJ, Shendure J. A combination of transcription factors mediates inducible interchromosomal contacts. eLife 2019; 8:e42499. [PMID: 31081754 PMCID: PMC6548505 DOI: 10.7554/elife.42499] [Citation(s) in RCA: 12] [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: 10/02/2018] [Accepted: 05/11/2019] [Indexed: 12/30/2022] Open
Abstract
The genome forms specific three-dimensional contacts in response to cellular or environmental conditions. However, it remains largely unknown which proteins specify and mediate such contacts. Here we describe an assay, MAP-C (Mutation Analysis in Pools by Chromosome conformation capture), that simultaneously characterizes the effects of hundreds of cis or trans-acting mutations on a chromosomal contact. Using MAP-C, we show that inducible interchromosomal pairing between HAS1pr-TDA1pr alleles in saturated cultures of Saccharomyces yeast is mediated by three transcription factors, Leu3, Sdd4 (Ypr022c), and Rgt1. The coincident, combined binding of all three factors is strongest at the HAS1pr-TDA1pr locus and is also specific to saturated conditions. We applied MAP-C to further explore the biochemical mechanism of these contacts, and find they require the structured regulatory domain of Rgt1, but no known interaction partners of Rgt1. Altogether, our results demonstrate MAP-C as a powerful method for dissecting the mechanistic basis of chromosome conformation.
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Affiliation(s)
- Seungsoo Kim
- Department of Genome SciencesUniversity of WashingtonSeattleUnited States
| | - Maitreya J Dunham
- Department of Genome SciencesUniversity of WashingtonSeattleUnited States
| | - Jay Shendure
- Department of Genome SciencesUniversity of WashingtonSeattleUnited States
- Howard Hughes Medical InstituteSeattleUnited States
- Brotman Baty Institute for Precision MedicineSeattleUnited States
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18
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Bewick AJ, Hofmeister BT, Powers RA, Mondo SJ, Grigoriev IV, James TY, Stajich JE, Schmitz RJ. Diversity of cytosine methylation across the fungal tree of life. Nat Ecol Evol 2019; 3:479-490. [PMID: 30778188 PMCID: PMC6533610 DOI: 10.1038/s41559-019-0810-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 01/13/2019] [Indexed: 12/22/2022]
Abstract
The generation of thousands of fungal genomes is leading to a better understanding of genes and genomic organization within the kingdom. However, the epigenome, which includes DNA and chromatin modifications, remains poorly investigated in fungi. Large comparative studies in animals and plants have deepened our understanding of epigenomic variation, particularly of the modified base 5-methylcytosine (5mC), but taxonomic sampling of disparate groups is needed to develop unifying explanations for 5mC variation. Here we utilize the largest phylogenetic resolution of 5mC methyltransferases (5mC MTases) and genome evolution to better understand levels and patterns of 5mC across fungi. We show that extant 5mC MTase genotypes are descendent from ancestral maintenance and de novo genotypes, whereas the 5mC MTases DIM-2 and RID are more recently derived, and that 5mC levels are correlated with 5mC MTase genotype and transposon content. Our survey also revealed that fungi lack canonical gene body methylation, which distinguishes fungal epigenomes from certain insect and plant species. However, some fungal species possess independently derived clusters of contiguous 5mC encompassing many genes. In some cases, DNA repair pathways and the N6-methyladenine (6mA) DNA modification negatively coevolved with 5mC pathways, which additionally contributed to interspecific epigenomic variation across fungi.
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Affiliation(s)
- Adam J Bewick
- Department of Genetics, University of Georgia, Athens, GA, USA.
| | | | - Rob A Powers
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Stephen J Mondo
- US Department of Energy Joint Genome Institute, Walnut Creek, Berkeley, CA, USA
| | - Igor V Grigoriev
- US Department of Energy Joint Genome Institute, Walnut Creek, Berkeley, CA, USA.,Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Timothy Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Jason E Stajich
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, USA
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19
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Van de Wouw AP, Elliott CE, Popa KM, Idnurm A. Analysis of Repeat Induced Point (RIP) Mutations in Leptosphaeria maculans Indicates Variability in the RIP Process Between Fungal Species. Genetics 2019; 211:89-104. [PMID: 30389803 PMCID: PMC6325690 DOI: 10.1534/genetics.118.301712] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/24/2018] [Indexed: 01/01/2023] Open
Abstract
Gene duplication contributes to evolutionary potential, yet many duplications in a genome arise from the activity of "selfish" genetic elements such as transposable elements. Fungi have a number of mechanisms by which they limit the expansion of transposons, including Repeat Induced Point mutation (RIP). RIP has been best characterized in the Sordariomycete Neurospora crassa, wherein duplicated DNA regions are recognized after cell fusion, but before nuclear fusion during the sexual cycle, and then mutated. While "signatures" of RIP appear in the genome sequences of many fungi, the species most distant from N. crassa in which the process has been experimentally demonstrated to occur is the Dothideomycete Leptosphaeria maculans In the current study, we show that similar to N. crassa, nonlinked duplications can trigger RIP; however, the frequency of the generated RIP mutations is extremely low in L maculans (< 0.1%) and requires a large duplication to initiate RIP, and that multiple premeiotic mitoses are involved in the RIP process. However, a single sexual cycle leads to the generation of progeny with unique haplotypes, despite progeny pairs being generated from mitosis. We hypothesize that these different haplotypes may be the result of the deamination process occurring post karyogamy, leading to unique mutations within each of the progeny pairs. These findings indicate that the RIP process, while common to many fungi, differs between fungi and that this impacts on the fate of duplicated DNA.
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Affiliation(s)
- Angela P Van de Wouw
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Candace E Elliott
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Kerryn M Popa
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alexander Idnurm
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
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Partition of Repeat-Induced Point Mutations Reveals Structural Aspects of Homologous DNA-DNA Pairing. Biophys J 2018; 115:605-615. [PMID: 30086830 DOI: 10.1016/j.bpj.2018.06.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/28/2018] [Indexed: 11/21/2022] Open
Abstract
In some fungi, a premeiotic process known as repeat-induced point mutation (RIP) can accurately identify and mutate nearly all gene-sized DNA repeats present in the haploid germline nuclei. Studies in Neurospora crassa have suggested that RIP detects sequence homology directly between intact DNA double helices, without strand separation and without the participation of RecA-like proteins. Those studies used the aggregated number of RIP mutations as a simple quantitative measure of RIP activity. Additional structural information about homologous DNA-DNA pairing during RIP can be extracted by analyzing spatial distributions of RIP mutations converted into profiles of partitioned RIP propensity (PRP). Further analysis shows that PRP is strongly affected by the topological configuration and the relative positioning of the participating DNA segments. Most notably, pairs of closely positioned repeats produce very distinct PRP profiles depending on whether these repeats are present in the direct or the inverted orientation. Such an effect can be attributed to a topology-dependent redistribution of the supercoiling stress created by the predicted limited untwisting of the DNA segments during pairing. This and other results raise a possibility that such pairing-induced fluctuations in DNA supercoiling can modulate the overall structure and properties of repetitive DNA. Such effects can be particularly strong in the context of long tandem-repeat arrays that are typically present in the pericentromeric and centromeric regions of chromosomes in many species of plants, fungi, and animals, including humans.
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Abstract
Transposable elements have colonized the genomes of nearly all organisms, including fungi. Although transposable elements may sometimes provide beneficial functions to their hosts their overall impact is considered deleterious. As a result, the activity of transposable elements needs to be counterbalanced by the host genome defenses. In fungi, the primary genome defense mechanisms include repeat-induced point mutation (RIP) and methylation induced premeiotically, meiotic silencing by unpaired DNA, sex-induced silencing, cosuppression (also known as somatic quelling), and cotranscriptional RNA surveillance. Recent studies of the filamentous fungus Neurospora crassa have shown that the process of repeat recognition for RIP apparently involves interactions between coaligned double-stranded segments of chromosomal DNA. These studies have also shown that RIP can be mediated by the conserved pathway that establishes transcriptional (heterochromatic) silencing of repetitive DNA. In light of these new findings, RIP emerges as a specialized case of the general phenomenon of heterochromatic silencing of repetitive DNA.
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22
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Li WC, Chen CL, Wang TF. Repeat-induced point (RIP) mutation in the industrial workhorse fungus Trichoderma reesei. Appl Microbiol Biotechnol 2018; 102:1567-1574. [DOI: 10.1007/s00253-017-8731-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 12/18/2017] [Accepted: 12/20/2017] [Indexed: 02/01/2023]
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