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Matthey-Doret C, Colp MJ, Escoll P, Thierry A, Moreau P, Curtis B, Sahr T, Sarrasin M, Gray MW, Lang BF, Archibald JM, Buchrieser C, Koszul R. Chromosome-scale assemblies of Acanthamoeba castellanii genomes provide insights into Legionella pneumophila infection-related chromatin reorganization. Genome Res 2022; 32:gr.276375.121. [PMID: 36109147 PMCID: PMC9528979 DOI: 10.1101/gr.276375.121] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 07/25/2022] [Indexed: 11/24/2022]
Abstract
The unicellular amoeba Acanthamoeba castellanii is ubiquitous in aquatic environments, where it preys on bacteria. The organism also hosts bacterial endosymbionts, some of which are parasitic, including human pathogens such as Chlamydia and Legionella spp. Here we report complete, high-quality genome sequences for two extensively studied A. castellanii strains, Neff and C3. Combining long- and short-read data with Hi-C, we generated near chromosome-level assemblies for both strains with 90% of the genome contained in 29 scaffolds for the Neff strain and 31 for the C3 strain. Comparative genomics revealed strain-specific functional enrichment, most notably genes related to signal transduction in the C3 strain and to viral replication in Neff. Furthermore, we characterized the spatial organization of the A. castellanii genome and showed that it is reorganized during infection by Legionella pneumophila Infection-dependent chromatin loops were found to be enriched in genes for signal transduction and phosphorylation processes. In genomic regions where chromatin organization changed during Legionella infection, we found functional enrichment for genes associated with metabolism, organelle assembly, and cytoskeleton organization. Given Legionella infection is known to alter its host's cell cycle, to exploit the host's organelles, and to modulate the host's metabolism in its favor, these changes in chromatin organization may partly be related to mechanisms of host control during Legionella infection.
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Affiliation(s)
- Cyril Matthey-Doret
- Institut Pasteur, CNRS UMR 3525, Université de Paris, Unité Régulation Spatiale des Génomes, F-75015 Paris, France
- Collège Doctoral, Sorbonne Université, F-75005 Paris, France
| | - Morgan J Colp
- Department of Biochemistry and Molecular Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Pedro Escoll
- Institut Pasteur, Université de Paris, Biologie des Bactéries Intracellulaires and CNRS UMR 6047, F-75015 Paris, France
| | - Agnès Thierry
- Institut Pasteur, CNRS UMR 3525, Université de Paris, Unité Régulation Spatiale des Génomes, F-75015 Paris, France
| | - Pierrick Moreau
- Institut Pasteur, CNRS UMR 3525, Université de Paris, Unité Régulation Spatiale des Génomes, F-75015 Paris, France
| | - Bruce Curtis
- Department of Biochemistry and Molecular Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Tobias Sahr
- Institut Pasteur, Université de Paris, Biologie des Bactéries Intracellulaires and CNRS UMR 6047, F-75015 Paris, France
| | - Matt Sarrasin
- Robert Cedergren Centre for Bioinformatics and Genomics, Département de Biochimie, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Michael W Gray
- Department of Biochemistry and Molecular Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - B Franz Lang
- Robert Cedergren Centre for Bioinformatics and Genomics, Département de Biochimie, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - John M Archibald
- Department of Biochemistry and Molecular Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Carmen Buchrieser
- Institut Pasteur, Université de Paris, Biologie des Bactéries Intracellulaires and CNRS UMR 6047, F-75015 Paris, France
| | - Romain Koszul
- Institut Pasteur, CNRS UMR 3525, Université de Paris, Unité Régulation Spatiale des Génomes, F-75015 Paris, France
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2
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Fractional 2'-O-methylation in the ribosomal RNA of Dictyostelium discoideum supports ribosome heterogeneity in Amoebozoa. Sci Rep 2022; 12:1952. [PMID: 35121764 PMCID: PMC8817022 DOI: 10.1038/s41598-022-05447-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 01/07/2022] [Indexed: 12/02/2022] Open
Abstract
A hallmark of ribosomal RNA (rRNA) are 2′-O-methyl groups that are introduced sequence specifically by box C/D small nucleolar RNAs (snoRNAs) in ribonucleoprotein particles. Most data on this chemical modification and its impact on RNA folding and stability are derived from organisms of the Opisthokonta supergroup. Using bioinformatics and RNA-seq data, we identify 30 novel box C/D snoRNAs in Dictyostelium discoideum, many of which are differentially expressed during the multicellular development of the amoeba. By applying RiboMeth-seq, we find 49 positions in the 17S and 26S rRNA 2′-O-methylated. Several of these nucleotides are substoichiometrically modified, with one displaying dynamic modification levels during development. Using homology-based models for the D. discoideum rRNA secondary structures, we localize many modified nucleotides in the vicinity of the ribosomal A, P and E sites. For most modified positions, a guiding box C/D snoRNA could be identified, allowing to determine idiosyncratic features of the snoRNA/rRNA interactions in the amoeba. Our data from D. discoideum represents the first evidence for ribosome heterogeneity in the Amoebozoa supergroup, allowing to suggest that it is a common feature of all eukaryotes.
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3
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Kjellin J, Pränting M, Bach F, Vaid R, Edelbroek B, Li Z, Hoeppner MP, Grabherr M, Isberg RR, Hagedorn M, Söderbom F. Investigation of the host transcriptional response to intracellular bacterial infection using Dictyostelium discoideum as a host model. BMC Genomics 2019; 20:961. [PMID: 31823727 PMCID: PMC6902447 DOI: 10.1186/s12864-019-6269-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 11/07/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND During infection by intracellular pathogens, a highly complex interplay occurs between the infected cell trying to degrade the invader and the pathogen which actively manipulates the host cell to enable survival and proliferation. Many intracellular pathogens pose important threats to human health and major efforts have been undertaken to better understand the host-pathogen interactions that eventually determine the outcome of the infection. Over the last decades, the unicellular eukaryote Dictyostelium discoideum has become an established infection model, serving as a surrogate macrophage that can be infected with a wide range of intracellular pathogens. In this study, we use high-throughput RNA-sequencing to analyze the transcriptional response of D. discoideum when infected with Mycobacterium marinum and Legionella pneumophila. The results were compared to available data from human macrophages. RESULTS The majority of the transcriptional regulation triggered by the two pathogens was found to be unique for each bacterial challenge. Hallmark transcriptional signatures were identified for each infection, e.g. induction of endosomal sorting complexes required for transport (ESCRT) and autophagy genes in response to M. marinum and inhibition of genes associated with the translation machinery and energy metabolism in response to L. pneumophila. However, a common response to the pathogenic bacteria was also identified, which was not induced by non-pathogenic food bacteria. Finally, comparison with available data sets of regulation in human monocyte derived macrophages shows that the elicited response in D. discoideum is in many aspects similar to what has been observed in human immune cells in response to Mycobacterium tuberculosis and L. pneumophila. CONCLUSIONS Our study presents high-throughput characterization of D. discoideum transcriptional response to intracellular pathogens using RNA-seq. We demonstrate that the transcriptional response is in essence distinct to each pathogen and that in many cases, the corresponding regulation is recapitulated in human macrophages after infection by mycobacteria and L. pneumophila. This indicates that host-pathogen interactions are evolutionary conserved, derived from the early interactions between free-living phagocytic cells and bacteria. Taken together, our results strengthen the use of D. discoideum as a general infection model.
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Affiliation(s)
- Jonas Kjellin
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.
| | - Maria Pränting
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.,Present Address: ReAct - Action on Antibiotic Resistance, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Frauke Bach
- Section Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.,Present Address: Department of Stem Cell Transplantation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Roshan Vaid
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.,Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Bart Edelbroek
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Zhiru Li
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.,Present Address: New England Biolabs, Ipswich, MA, USA
| | - Marc P Hoeppner
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.,Institute of Clinical Molecular Biology, Kiel University, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Manfred Grabherr
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Ralph R Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Monica Hagedorn
- Section Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.,Life Sciences and Chemistry, Jacobs University Bremen gGmbH, Group Ribogenetics, Bremen, Germany
| | - Fredrik Söderbom
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.
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4
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Rodriguez-Centeno J, Manguán-García C, Perona R, Sastre L. Structure of Dictyostelium discoideum telomeres. Analysis of possible replication mechanisms. PLoS One 2019; 14:e0222909. [PMID: 31550289 PMCID: PMC6759168 DOI: 10.1371/journal.pone.0222909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 09/10/2019] [Indexed: 12/14/2022] Open
Abstract
Telomeres are nucleo-protein structures that protect the ends of eukaryotic chromosomes. They are not completely synthesized during DNA replication and are elongated by specific mechanisms. The structure of the telomeres and the elongation mechanism have not been determined in Dictyostelium discoideum. This organism presents extrachromosomal palindromic elements containing two copies of the rDNA, also present at the end of the chromosomes. In this article the structure of the terminal region of the rDNA is shown to consist of repetitions of the A(G)n sequence where the number of Gs is variable. These repeats extend as a 3’ single stranded region. The G-rich region is preceded by four tandem repetitions of two different DNA motifs. D. discoideum telomere reverse transcriptase homologous protein (TERTHP) presented RNase-sensitive enzymatic activity and was required to maintain telomere structure since terthp-mutant strains presented reorganizations of the DNA terminal regions. These modifications were different in several terthp-mutants and changed with their prolonged culture and subcloning. However, the terthp gene is not essential for D. discoideum proliferation. Telomeres could be maintained in terthp-mutant strains by homologous recombination mechanisms such as ALT (Alternative Lengthening of Telomeres) or HAATI (heterochromatin amplification-mediated and telomerase-independent). In agreement with this hypothesis, the expression of mRNAs coding for several proteins involved in homologous recombination was induced in terthp-mutant strains. Extrachromosomal rDNA could serve as substrate in these DNA homologous recombination reactions.
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Affiliation(s)
- Javier Rodriguez-Centeno
- Instituto de Investigaciones Biomédicas CSIC/UAM, C/ Arturo Duperier, IdiPaz, C/Pedro Rico, Madrid, Spain
| | - Cristina Manguán-García
- Instituto de Investigaciones Biomédicas CSIC/UAM, C/ Arturo Duperier, IdiPaz, C/Pedro Rico, Madrid, Spain
- CIBER de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Rosario Perona
- Instituto de Investigaciones Biomédicas CSIC/UAM, C/ Arturo Duperier, IdiPaz, C/Pedro Rico, Madrid, Spain
- CIBER de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Leandro Sastre
- Instituto de Investigaciones Biomédicas CSIC/UAM, C/ Arturo Duperier, IdiPaz, C/Pedro Rico, Madrid, Spain
- CIBER de Enfermedades Raras (CIBERER), Madrid, Spain
- * E-mail:
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5
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Abstract
Sex promotes the recombination and reassortment of genetic material and is prevalent across eukaryotes, although our knowledge of the molecular details of sexual inheritance is scant in several major lineages. In social amoebae, sex involves a promiscuous mixing of cytoplasm before zygotes consume the majority of cells, but for technical reasons, sexual progeny have been difficult to obtain and study. We report here genome-wide characterization of meiotic progeny in Dictyostelium discoideum We find that recombination occurs at high frequency in pairwise crosses between all three mating types, despite the absence of the Spo11 enzyme that is normally required to initiate crossover formation. Fusions of more than two gametes to form transient syncytia lead to frequent triparental inheritance, with haploid meiotic progeny bearing recombined nuclear haplotypes from two parents and the mitochondrial genome from a third. Cells that do not contribute genetically to the Dictyostelium zygote nucleus thereby have a stake in the next haploid generation. D. discoideum mitochondrial genomes are polymorphic, and our findings raise the possibility that some of this variation might be a result of sexual selection on genes that can promote the spread of individual organelle genomes during sex. This kind of self-interested mitochondrial behavior may have had important consequences during eukaryogenesis and the initial evolution of sex.
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6
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Fey P, Dodson RJ, Basu S, Hartline EC, Chisholm RL. dictyBase and the Dicty Stock Center (version 2.0) - a progress report. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2019; 63:563-572. [PMID: 31840793 PMCID: PMC7409682 DOI: 10.1387/ijdb.190226pf] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
After serving the Dictyostelium community for many years, the first version of dictyBase (Chisholm et al., 2006; Fey et al., 2006) was in need of a decisive update. The original dictyBase software was not adaptable to more current demands such as handling the import of large-scale data from recently sequenced genomes, keeping up with changes in the Gene Ontology (GO), or handling the automatic annotation of over 20,000 new strains. Therefore, we have embarked on a complete overhaul of dictyBase. The new infrastructure will allow the introduction of new data, such as more expressive GO annotations and Dictyostelium disease orthologs. A modern user interface aims to streamline usage of the database including orders from the Dicty Stock Center (DSC). New displays will allow novel views including the combination of data in two new tools. With the underlying software infrastructure now in place, dictyBase software engineers and curators are currently adding the user interfaces, new tools and content pages for the evolving version 2.0 of dictyBase. This review highlights the emerging status of the new dictyBase, updated pages and annotations that will soon be available in the new environment, an overview of our annotation procedures, and plans to involve the community in curation efforts.
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Affiliation(s)
- Petra Fey
- Northwestern University, Chicago, IL, USA.
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7
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Mathavarajah S, Flores A, Huber RJ. Dictyostelium discoideum
: A Model System for Cell and Developmental Biology. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/cpet.15] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Ana Flores
- Department of Biology, Trent University Peterborough Ontario Canada
| | - Robert J. Huber
- Department of Biology, Trent University Peterborough Ontario Canada
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8
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Malicki M, Iliopoulou M, Hammann C. Retrotransposon Domestication and Control in Dictyostelium discoideum. Front Microbiol 2017; 8:1869. [PMID: 29051748 PMCID: PMC5633606 DOI: 10.3389/fmicb.2017.01869] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/13/2017] [Indexed: 01/22/2023] Open
Abstract
Transposable elements, identified in all eukaryotes, are mobile genetic units that can change their genomic position. Transposons usually employ an excision and reintegration mechanism, by which they change position, but not copy number. In contrast, retrotransposons amplify via RNA intermediates, increasing their genomic copy number. Hence, they represent a particular threat to the structural and informational integrity of the invaded genome. The social amoeba Dictyostelium discoideum, model organism of the evolutionary Amoebozoa supergroup, features a haploid, gene-dense genome that offers limited space for damage-free transposition. Several of its contemporary retrotransposons display intrinsic integration preferences, for example by inserting next to transfer RNA genes or other retroelements. Likely, any retrotransposons that invaded the genome of the amoeba in a non-directed manner were lost during evolution, as this would result in decreased fitness of the organism. Thus, the positional preference of the Dictyostelium retroelements might represent a domestication of the selfish elements. Likewise, the reduced danger of such domesticated transposable elements led to their accumulation, and they represent about 10% of the current genome of D. discoideum. To prevent the uncontrolled spreading of retrotransposons, the amoeba employs control mechanisms including RNA interference and heterochromatization. Here, we review TRE5-A, DIRS-1 and Skipper-1, as representatives of the three retrotransposon classes in D. discoideum, which make up 5.7% of the Dictyostelium genome. We compile open questions with respect to their mobility and cellular regulation, and suggest strategies, how these questions might be addressed experimentally.
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Affiliation(s)
- Marek Malicki
- Ribogenetics Biochemistry Lab, Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Maro Iliopoulou
- Ribogenetics Biochemistry Lab, Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Christian Hammann
- Ribogenetics Biochemistry Lab, Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
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9
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Spaller T, Groth M, Glöckner G, Winckler T. TRE5-A retrotransposition profiling reveals putative RNA polymerase III transcription complex binding sites on the Dictyostelium extrachromosomal rDNA element. PLoS One 2017; 12:e0175729. [PMID: 28406973 PMCID: PMC5391098 DOI: 10.1371/journal.pone.0175729] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Accepted: 03/30/2017] [Indexed: 11/28/2022] Open
Abstract
The amoeba Dictyostelium discoideum has a haploid genome in which two thirds of the DNA encodes proteins. Consequently, the space available for selfish mobile elements to expand without excess damage to the host genome is limited. The non-long terminal repeat retrotransposon TRE5-A maintains an active population in the D. discoideum genome and apparently adapted to this gene-dense environment by targeting positions ~47 bp upstream of tRNA genes that are devoid of protein-coding regions. Because only ~24% of tRNA genes are associated with a TRE5-A element in the reference genome, we evaluated whether TRE5-A retrotransposition is limited to this subset of tRNA genes. We determined that a tagged TRE5-A element (TRE5-Absr) integrated at 384 of 405 tRNA genes, suggesting that expansion of the current natural TRE5-A population is not limited by the availability of targets. We further observed that TRE5-Absr targets the ribosomal 5S gene on the multicopy extrachromosomal DNA element that carries the ribosomal RNA genes, indicating that TRE5-A integration may extend to the entire RNA polymerase III (Pol III) transcriptome. We determined that both natural TRE5-A and cloned TRE5-Absr retrotranspose to locations on the extrachromosomal rDNA element that contain tRNA gene-typical A/B box promoter motifs without displaying any other tRNA gene context. Based on previous data suggesting that TRE5-A targets tRNA genes by locating Pol III transcription complexes, we propose that A/B box loci reflect Pol III transcription complex assembly sites that possess a function in the biology of the extrachromosomal rDNA element.
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MESH Headings
- Binding Sites
- DNA, Protozoan/chemistry
- DNA, Protozoan/genetics
- DNA, Protozoan/metabolism
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- DNA, Ribosomal/metabolism
- Dictyostelium/genetics
- Promoter Regions, Genetic
- Protozoan Proteins/metabolism
- RNA Polymerase III/metabolism
- RNA, Ribosomal, 5S/genetics
- RNA, Transfer/genetics
- Retroelements/genetics
- Transcription, Genetic
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Affiliation(s)
- Thomas Spaller
- Pharmaceutical Biology, Institute of Pharmacy, University of Jena, Jena, Germany
| | - Marco Groth
- Core Facility DNA Sequencing, Leibniz Institute for Age Research–Fritz Lipmann Institute, Jena, Germany
| | - Gernot Glöckner
- Institute for Biochemistry I, Medical Faculty, University of Cologne, Cologne, Germany
| | - Thomas Winckler
- Pharmaceutical Biology, Institute of Pharmacy, University of Jena, Jena, Germany
- * E-mail:
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10
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The Long Noncoding RNA Transcriptome of Dictyostelium discoideum Development. G3-GENES GENOMES GENETICS 2017; 7:387-398. [PMID: 27932387 PMCID: PMC5295588 DOI: 10.1534/g3.116.037150] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Dictyostelium discoideum live in the soil as single cells, engulfing bacteria and growing vegetatively. Upon starvation, tens of thousands of amoebae enter a developmental program that includes aggregation, multicellular differentiation, and sporulation. Major shifts across the protein-coding transcriptome accompany these developmental changes. However, no study has presented a global survey of long noncoding RNAs (ncRNAs) in D. discoideum To characterize the antisense and long intergenic noncoding RNA (lncRNA) transcriptome, we analyzed previously published developmental time course samples using an RNA-sequencing (RNA-seq) library preparation method that selectively depletes ribosomal RNAs (rRNAs). We detected the accumulation of transcripts for 9833 protein-coding messenger RNAs (mRNAs), 621 lncRNAs, and 162 putative antisense RNAs (asRNAs). The noncoding RNAs were interspersed throughout the genome, and were distinct in expression level, length, and nucleotide composition. The noncoding transcriptome displayed a temporal profile similar to the coding transcriptome, with stages of gradual change interspersed with larger leaps. The transcription profiles of some noncoding RNAs were strongly correlated with known differentially expressed coding RNAs, hinting at a functional role for these molecules during development. Examining the mitochondrial transcriptome, we modeled two novel antisense transcripts. We applied yet another ribosomal depletion method to a subset of the samples to better retain transfer RNA (tRNA) transcripts. We observed polymorphisms in tRNA anticodons that suggested a post-transcriptional means by which D. discoideum compensates for codons missing in the genomic complement of tRNAs. We concluded that the prevalence and characteristics of long ncRNAs indicate that these molecules are relevant to the progression of molecular and cellular phenotypes during development.
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11
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Burgute BD, Peche VS, Müller R, Matthias J, Gaßen B, Eichinger L, Glöckner G, Noegel AA. The C-Terminal SynMuv/DdDUF926 Domain Regulates the Function of the N-Terminal Domain of DdNKAP. PLoS One 2016; 11:e0168617. [PMID: 27997579 PMCID: PMC5173251 DOI: 10.1371/journal.pone.0168617] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/11/2016] [Indexed: 11/18/2022] Open
Abstract
NKAP (NF-κB activating protein) is a highly conserved SR (serine/arginine-rich) protein involved in transcriptional control and splicing in mammals. We identified DdNKAP, the Dictyostelium discoideum ortholog of mammalian NKAP, as interacting partner of the nuclear envelope protein SUN-1. DdNKAP harbors a number of basic RDR/RDRS repeats in its N-terminal domain and the SynMuv/DUF926 domain at its C-terminus. We describe a novel and direct interaction between DdNKAP and Prp19 (Pre mRNA processing factor 19) which might be relevant for the observed DdNKAP ubiquitination. Genome wide analysis using cross-linking immunoprecipitation-high-throughput sequencing (CLIP-seq) revealed DdNKAP association with intergenic regions, exons, introns and non-coding RNAs. Ectopic expression of DdNKAP and its domains affects several developmental aspects like stream formation, aggregation, and chemotaxis. We conclude that DdNKAP is a multifunctional protein, which might influence Dictyostelium development through its interaction with RNA and RNA binding proteins. Mutants overexpressing full length DdNKAP and the N-terminal domain alone (DdN-NKAP) showed opposite phenotypes in development and opposite expression profiles of several genes and rRNAs. The observed interaction between DdN-NKAP and the DdDUF926 domain indicates that the DdDUF926 domain acts as negative regulator of the N-terminus.
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Affiliation(s)
- Bhagyashri D. Burgute
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Vivek S. Peche
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Rolf Müller
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Jan Matthias
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Berthold Gaßen
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Ludwig Eichinger
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Gernot Glöckner
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, IGB, Berlin, Germany
| | - Angelika A. Noegel
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, Germany
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12
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Rosengarten RD, Beltran PR, Shaulsky G. A deep coverage Dictyostelium discoideum genomic DNA library replicates stably in Escherichia coli. Genomics 2015; 106:249-55. [PMID: 26028264 DOI: 10.1016/j.ygeno.2015.05.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 05/11/2015] [Accepted: 05/18/2015] [Indexed: 01/18/2023]
Abstract
The natural history of the amoeba Dictyostelium discoideum has inspired scientific inquiry for seventy-five years. A genetically tractable haploid eukaryote, D. discoideum appeals as a laboratory model as well. However, certain rote molecular genetic tasks, such as PCR and cloning, are difficult due to the AT-richness and low complexity of its genome. Here we report on the construction of a ~20 fold coverage D. discoideum genomic library in Escherichia coli, cloning 4-10 kilobase partial restriction fragments into a linear vector. End-sequencing indicates that most clones map to the six chromosomes in an unbiased distribution. Over 70% of these clones contain at least one complete open reading frame. We demonstrate that individual clones and library composition are stable over multiple replication cycles. Our library will enable numerous molecular biological applications and the completion of additional species' genome sequences, and suggests a path towards the long-elusive goal of genetic complementation.
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Affiliation(s)
- Rafael D Rosengarten
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Pamela R Beltran
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Gad Shaulsky
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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Figueroa RI, Cuadrado A, Stüken A, Rodríguez F, Fraga S. Ribosomal DNA Organization Patterns within the Dinoflagellate Genus Alexandrium as Revealed by FISH: Life Cycle and Evolutionary Implications. Protist 2014; 165:343-63. [DOI: 10.1016/j.protis.2014.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 04/03/2014] [Accepted: 04/08/2014] [Indexed: 10/25/2022]
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14
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Hofmann P, Kruse J, Hammann C. Transcript localization in Dictyostelium discoideum cells by RNA FISH. Methods Mol Biol 2013; 983:311-23. [PMID: 23494315 DOI: 10.1007/978-1-62703-302-2_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Biogenesis of ribosomal RNA (rRNA) takes place preliminary in the nucleolus of eukaryotic cells, the site of rDNA transcription. Several processing steps of rRNA molecules have been implied to take place in the cytoplasm. To follow these processing events we have adapted protocols for fluorescence in situ hybridization (FISH) for use in Dictyostelium discoideum. We describe methods for the generation of suitable fluorescently labeled probes and the fixation of cells, by which we have localized different precursor and mature rRNA molecules to the nucleolus or the cytoplasm, respectively.
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Affiliation(s)
- Patrick Hofmann
- Heisenberg Research Group Ribogenetics, Technical University of Darmstadt, Darmstadt, Germany
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15
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Fey P, Dodson RJ, Basu S, Chisholm RL. One stop shop for everything Dictyostelium: dictyBase and the Dicty Stock Center in 2012. Methods Mol Biol 2013; 983:59-92. [PMID: 23494302 DOI: 10.1007/978-1-62703-302-2_4] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
dictyBase (http://dictybase.org), the model organism database for Dictyostelium discoideum, includes the complete genome sequence and expression data for this organism. Relevant literature is integrated into the database, and gene models and functional annotation are manually curated from experimental results and comparative multigenome analyses. dictyBase has recently expanded to include the genome sequences of three additional Dictyostelids and has added new software tools to facilitate multigenome comparisons. The Dicty Stock Center, a strain and plasmid repository for Dictyostelium research, has relocated to Northwestern University in 2009. This allowed us integrating all Dictyostelium resources to better serve the research community. In this chapter, we will describe how to navigate the Web site and highlight some of our newer improvements.
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Affiliation(s)
- Petra Fey
- dictyBase and the Dicty Stock Center, Center for Genetic Medicine, Northwestern University, Chicago, IL, USA.
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16
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Basu S, Fey P, Pandit Y, Dodson R, Kibbe WA, Chisholm RL. DictyBase 2013: integrating multiple Dictyostelid species. Nucleic Acids Res 2012; 41:D676-83. [PMID: 23172289 PMCID: PMC3531180 DOI: 10.1093/nar/gks1064] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
dictyBase (http://dictybase.org) is the model organism database for the social amoeba Dictyostelium discoideum. This contribution provides an update on dictyBase that has been previously presented. During the past 3 years, dictyBase has taken significant strides toward becoming a genome portal for the whole Amoebozoa clade. In its latest release, dictyBase has scaled up to host multiple Dictyostelids, including Dictyostelium purpureum [Sucgang, Kuo, Tian, Salerno, Parikh, Feasley, Dalin, Tu, Huang, Barry et al.(2011) (Comparative genomics of the social amoebae Dictyostelium discoideum and Dictyostelium purpureum. Genome Biol., 12, R20)], Dictyostelium fasciculatum and Polysphondylium pallidum [Heidel, Lawal, Felder, Schilde, Helps, Tunggal, Rivero, John, Schleicher, Eichinger et al. (2011) (Phylogeny-wide analysis of social amoeba genomes highlights ancient origins for complex intercellular communication. Genome Res., 21, 1882–1891)]. The new release includes a new Genome Browser with RNAseq expression, interspecies Basic Local Alignment Search Tool alignments and a unified Basic Local Alignment Search Tool search for cross-species comparisons.
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Affiliation(s)
- Siddhartha Basu
- Biomedical Informatics Center and Center for Genetic Medicine, Northwestern Univesity, Feinberg School of Medicine, 750 North Lake Shore Drive, Chicago, IL 60611, USA
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Glöckner G, Noegel AA. Comparative genomics in the Amoebozoa clade. Biol Rev Camb Philos Soc 2012; 88:215-25. [PMID: 23134060 DOI: 10.1111/j.1469-185x.2012.00248.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 09/25/2012] [Accepted: 10/05/2012] [Indexed: 11/30/2022]
Abstract
Amoeboid life forms can be found throughout the evolutionary tree. The greatest proportion of these life forms is found in the Amoebozoa clade, one of the six major eukaryote evolutionary branches. Despite its common origin this clade exhibits a wide diversity of lifestyles including free-living and parasitic species and species with multicellular and multinucleate life stages. In this group, development, cooperation, and social behaviour can be studied in addition to traits common to unicellular organisms. To date, only a few Amoebozoa genomes have been sequenced completely, however a number of expressed sequence tags (ESTs) and complete and draft genomes have become available recently for several species that represent some of the major evolutionary lineages in this clade. This resource allows us to compare and analyse the evolutionary history and fate of branch-specific genes if properly exploited. Despite the large evolutionary time scale since the emergence of the major groups the genomic organization in Amoebozoa has retained common features. The number of Amoebozoa-specific genetic inventions seems to be rather small. The emergence of subgroups is accompanied by gene and domain losses and acquisitions of bacterial gene material. The sophisticated developmental cycles of Myxogastria and Dictyosteliida likely have a common origin and are deeply rooted in amoebozoan evolution. In this review we describe initial approaches to comparative genomics in Amoebozoa, summarize recent findings, and identify goals for further studies.
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Affiliation(s)
- Gernot Glöckner
- Institute for Freshwater Ecology and Inland Fisheries, IGB, Müggelseedamm 301, Berlin, D-12587, Germany.
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18
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Heidel AJ, Lawal HM, Felder M, Schilde C, Helps NR, Tunggal B, Rivero F, John U, Schleicher M, Eichinger L, Platzer M, Noegel AA, Schaap P, Glöckner G. Phylogeny-wide analysis of social amoeba genomes highlights ancient origins for complex intercellular communication. Genome Res 2011; 21:1882-91. [PMID: 21757610 PMCID: PMC3205573 DOI: 10.1101/gr.121137.111] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 07/11/2011] [Indexed: 11/24/2022]
Abstract
Dictyostelium discoideum (DD), an extensively studied model organism for cell and developmental biology, belongs to the most derived group 4 of social amoebas, a clade of altruistic multicellular organisms. To understand genome evolution over long time periods and the genetic basis of social evolution, we sequenced the genomes of Dictyostelium fasciculatum (DF) and Polysphondylium pallidum (PP), which represent the early diverging groups 1 and 2, respectively. In contrast to DD, PP and DF have conventional telomere organization and strongly reduced numbers of transposable elements. The number of protein-coding genes is similar between species, but only half of them comprise an identifiable set of orthologous genes. In general, genes involved in primary metabolism, cytoskeletal functions and signal transduction are conserved, while genes involved in secondary metabolism, export, and signal perception underwent large differential gene family expansions. This most likely signifies involvement of the conserved set in core cell and developmental mechanisms, and of the diverged set in niche- and species-specific adaptations for defense and food, mate, and kin selection. Phylogenetic dating using a concatenated data set and extensive loss of synteny indicate that DF, PP, and DD split from their last common ancestor at least 0.6 billion years ago.
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Affiliation(s)
- Andrew J. Heidel
- Leibniz Institute for Age Research–Fritz Lipmann Institute, D-07745 Jena, Germany
| | - Hajara M. Lawal
- College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Marius Felder
- Leibniz Institute for Age Research–Fritz Lipmann Institute, D-07745 Jena, Germany
| | - Christina Schilde
- College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Nicholas R. Helps
- College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Budi Tunggal
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, D-50931 Cologne, Germany
| | - Francisco Rivero
- Hull York Medical School and Department of Biological Sciences, University of Hull, Hull HU6 7RX, United Kingdom
| | - Uwe John
- Alfred Wegener Institute, D-27570 Bremerhaven, Germany
| | - Michael Schleicher
- Institute for Anatomy and Cell Biology, and Center for Integrated Protein Science (CIPSM), Ludwig-Maximilians-University Munich, D-80336 Munich, Germany
| | - Ludwig Eichinger
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, D-50931 Cologne, Germany
| | - Matthias Platzer
- Leibniz Institute for Age Research–Fritz Lipmann Institute, D-07745 Jena, Germany
| | - Angelika A. Noegel
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, D-50931 Cologne, Germany
| | - Pauline Schaap
- College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Gernot Glöckner
- Leibniz Institute for Age Research–Fritz Lipmann Institute, D-07745 Jena, Germany
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, D-50931 Cologne, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, D-12587 Berlin, Germany
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19
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Stevense M, Chubb JR, Muramoto T. Nuclear organization and transcriptional dynamics in Dictyostelium. Dev Growth Differ 2011; 53:576-86. [PMID: 21585360 DOI: 10.1111/j.1440-169x.2011.01271.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Dictyostelium model has a set of features uniquely well-suited to developing our understanding of transcriptional control. The complete Dictyostelium discoideum genome sequence has revealed that many of the molecular components regulating transcription in larger eukaryotes are conserved in Dictyostelium, from transcription factors and chromatin components to the enzymes and signals that regulate them. In addition, the system permits visualization of single gene firing events in living cells, which provides a more detailed view of transcription and its relationships to cell and developmental processes. This review will bring together the available knowledge of the structure and dynamics of the Dictyostelium nucleus and discuss recent transcription imaging studies and their implications for stability and accuracy of cell decisions.
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Affiliation(s)
- Michelle Stevense
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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20
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Siol O, Spaller T, Schiefner J, Winckler T. Genetically tagged TRE5-A retrotransposons reveal high amplification rates and authentic target site preference in the Dictyostelium discoideum genome. Nucleic Acids Res 2011; 39:6608-19. [PMID: 21525131 PMCID: PMC3159450 DOI: 10.1093/nar/gkr261] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 03/21/2011] [Accepted: 04/06/2011] [Indexed: 11/14/2022] Open
Abstract
Retrotransposons contribute significantly to the evolution of eukaryotic genomes. They replicate by producing DNA copies of their own RNA, which are integrated at new locations in the host cell genome. In the gene-dense genome of the social amoeba Dictyostelium discoideum, retrotransposon TRE5-A avoids insertional mutagenesis by targeting the transcription factor (TF) IIIC/IIIB complex and integrating ∼ 50 bp upstream of tRNA genes. We generated synthetic TRE5-A retrotransposons (TRE5-A(bsr)) that were tagged with a selection marker that conferred resistance to blasticidin after a complete retrotransposition cycle. We found that the TRE5-A(bsr) elements were efficiently mobilized in trans by proteins expressed from the endogenous TRE5-A population found in D. discoideum cells. ORF1 protein translated from TRE5-A(bsr) elements significantly enhanced retrotransposition. We observed that the 5' untranslated region of TRE5-A could be replaced by an unrelated promoter, whereas the 3' untranslated region of TRE5-A was essential for retrotransposition. A predicted secondary structure in the RNA of the 3' untranslated region of TRE5-A may be involved in the retrotransposition process. The TRE5-A(bsr) elements were capable of identifying authentic integration targets in vivo, including formerly unnoticed, putative binding sites for TFIIIC on the extrachromosomal DNA element that carries the ribosomal RNA genes.
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Affiliation(s)
| | | | | | - Thomas Winckler
- Department of Pharmaceutical Biology, School of Biology and Pharmacy, Institute of Pharmacy, University of Jena, Semmelweisstrasse 10, 07743 Jena, Germany
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21
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Boesler C, Kruse J, Söderbom F, Hammann C. Sequence and generation of mature ribosomal RNA transcripts in Dictyostelium discoideum. J Biol Chem 2011; 286:17693-703. [PMID: 21454536 DOI: 10.1074/jbc.m110.208306] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The amoeba Dictyostelium discoideum is a well established model organism for studying numerous aspects of cellular and developmental functions. Its ribosomal RNA (rRNA) is encoded in an extrachromosomal palindrome that exists in ∼100 copies in the cell. In this study, we have set out to investigate the sequence of the expressed rRNA. For this, we have ligated the rRNA ends and performed RT-PCR on these circular RNAs. Sequencing revealed that the mature 26 S, 17 S, 5.8 S, and 5 S rRNAs have sizes of 3741, 1871, 162, and 112 nucleotides, respectively. Unlike the published data, all mature rRNAs of the same type uniformly display the same start and end nucleotides in the analyzed AX2 strain. We show the existence of a short lived primary transcript covering the rRNA transcription unit of 17 S, 5.8 S, and 26 S rRNA. Northern blots and RT-PCR reveal that from this primary transcript two precursor molecules of the 17 S and two precursors of the 26 S rRNA are generated. We have also determined the sequences of these precursor molecules, and based on these data, we propose a model for the maturation of the rRNAs in Dictyostelium discoideum that we compare with the processing of the rRNA transcription unit of Saccharomyces cerevisiae.
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Affiliation(s)
- Carsten Boesler
- Heisenberg Research Group Ribogenetics, Technical University of Darmstadt, 64287 Darmstadt, Germany
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22
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Gaudet P, Fey P, Basu S, Bushmanova YA, Dodson R, Sheppard KA, Just EM, Kibbe WA, Chisholm RL. dictyBase update 2011: web 2.0 functionality and the initial steps towards a genome portal for the Amoebozoa. Nucleic Acids Res 2010; 39:D620-4. [PMID: 21087999 PMCID: PMC3013695 DOI: 10.1093/nar/gkq1103] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
dictyBase (http://www.dictybase.org), the model organism database for Dictyostelium, aims to provide the broad biomedical research community with well integrated, high quality data and tools for Dictyostelium discoideum and related species. dictyBase houses the complete genome sequence, ESTs, and the entire body of literature relevant to Dictyostelium. This information is curated to provide accurate gene models and functional annotations, with the goal of fully annotating the genome to provide a 'reference genome' in the Amoebozoa clade. We highlight several new features in the present update: (i) new annotations; (ii) improved interface with web 2.0 functionality; (iii) the initial steps towards a genome portal for the Amoebozoa; (iv) ortholog display; and (v) the complete integration of the Dicty Stock Center with dictyBase.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Rex L. Chisholm
- *To whom correspondence should be addressed. Tel: +1-312-503-3209;
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23
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Torres-Machorro AL, Hernández R, Cevallos AM, López-Villaseñor I. Ribosomal RNA genes in eukaryotic microorganisms: witnesses of phylogeny? FEMS Microbiol Rev 2010; 34:59-86. [DOI: 10.1111/j.1574-6976.2009.00196.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Fey P, Gaudet P, Curk T, Zupan B, Just EM, Basu S, Merchant SN, Bushmanova YA, Shaulsky G, Kibbe WA, Chisholm RL. dictyBase--a Dictyostelium bioinformatics resource update. Nucleic Acids Res 2009; 37:D515-9. [PMID: 18974179 PMCID: PMC2686522 DOI: 10.1093/nar/gkn844] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 10/14/2008] [Accepted: 10/15/2008] [Indexed: 12/14/2022] Open
Abstract
dictyBase (http://dictybase.org) is the model organism database for Dictyostelium discoideum. It houses the complete genome sequence, ESTs and the entire body of literature relevant to Dictyostelium. This information is curated to provide accurate gene models and functional annotations, with the goal of fully annotating the genome. This dictyBase update describes the annotations and features implemented since 2006, including improved strain and phenotype representation, integration of predicted transcriptional regulatory elements, protein domain information, biochemical pathways, improved searching and a wiki tool that allows members of the research community to provide annotations.
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Affiliation(s)
- Petra Fey
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Pascale Gaudet
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Tomaz Curk
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Blaz Zupan
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Eric M. Just
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Siddhartha Basu
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sohel N. Merchant
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yulia A. Bushmanova
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Gad Shaulsky
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Warren A. Kibbe
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rex L. Chisholm
- dictyBase, Northwestern University Biomedical Informatics Center and Center for Genetic Medicine, Chicago, IL 60611, USA, Faculty of Computer and Information Science, University of Ljubljana, Slovenia and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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25
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Larsson P, Hinas A, Ardell DH, Kirsebom LA, Virtanen A, Söderbom F. De novo search for non-coding RNA genes in the AT-rich genome of Dictyostelium discoideum: performance of Markov-dependent genome feature scoring. Genome Res 2008; 18:888-99. [PMID: 18347326 DOI: 10.1101/gr.069104.107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Genome data are increasingly important in the computational identification of novel regulatory non-coding RNAs (ncRNAs). However, most ncRNA gene-finders are either specialized to well-characterized ncRNA gene families or require comparisons of closely related genomes. We developed a method for de novo screening for ncRNA genes with a nucleotide composition that stands out against the background genome based on a partial sum process. We compared the performance when assuming independent and first-order Markov-dependent nucleotides, respectively, and used Karlin-Altschul and Karlin-Dembo statistics to evaluate the significance of hits. We hypothesized that a first-order Markov-dependent process might have better power to detect ncRNA genes since nearest-neighbor models have been shown to be successful in predicting RNA structures. A model based on a first-order partial sum process (analyzing overlapping dinucleotides) had better sensitivity and specificity than a zeroth-order model when applied to the AT-rich genome of the amoeba Dictyostelium discoideum. In this genome, we detected 94% of previously known ncRNA genes (at this sensitivity, the false positive rate was estimated to be 25% in a simulated background). The predictions were further refined by clustering candidate genes according to sequence similarity and/or searching for an ncRNA-associated upstream element. We experimentally verified six out of 10 tested ncRNA gene predictions. We conclude that higher-order models, in combination with other information, are useful for identification of novel ncRNA gene families in single-genome analysis of D. discoideum. Our generalizable approach extends the range of genomic data that can be searched for novel ncRNA genes using well-grounded statistical methods.
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Affiliation(s)
- Pontus Larsson
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, SE-75124 Uppsala, Sweden
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26
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Hinas A, Reimegård J, Wagner EGH, Nellen W, Ambros VR, Söderbom F. The small RNA repertoire of Dictyostelium discoideum and its regulation by components of the RNAi pathway. Nucleic Acids Res 2007; 35:6714-26. [PMID: 17916577 PMCID: PMC2175303 DOI: 10.1093/nar/gkm707] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Small RNAs play crucial roles in regulation of gene expression in many eukaryotes. Here, we report the cloning and characterization of 18–26 nt RNAs in the social amoeba Dictyostelium discoideum. This survey uncovered developmentally regulated microRNA candidates whose biogenesis, at least in one case, is dependent on a Dicer homolog, DrnB. Furthermore, we identified a large number of 21 nt RNAs originating from the DIRS-1 retrotransposon, clusters of which have been suggested to constitute centromeres. Small RNAs from another retrotransposon, Skipper, were significantly up-regulated in strains depleted of the second Dicer-like protein, DrnA, and a putative RNA-dependent RNA polymerase, RrpC. In contrast, the expression of DIRS-1 small RNAs was not altered in any of the analyzed strains. This suggests the presence of multiple RNAi pathways in D. discoideum. In addition, we isolated several small RNAs with antisense complementarity to mRNAs. Three of these mRNAs are developmentally regulated. Interestingly, all three corresponding genes express longer antisense RNAs from which the small RNAs may originate. In at least one case, the longer antisense RNA is complementary to the spliced but not the unspliced pre-mRNA, indicating synthesis by an RNA-dependent RNA polymerase.
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Affiliation(s)
- Andrea Hinas
- Department of Molecular Biology, Biomedical Center, Swedish University of Agricultural Sciences, Box 590, SE-75124 Uppsala, Sweden
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27
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Maruyama S, Nozaki H. Sequence and Intranuclear Location of the Extrachromosomal rDNA Plasmid of the Amoebo-Flagellate Naegleria gruberi. J Eukaryot Microbiol 2007; 54:333-7. [PMID: 17669158 DOI: 10.1111/j.1550-7408.2007.00273.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Several lower eukaryotic genomes have distinctive organization of rDNA on extrachromosomal molecules: the rDNAs of the amoebo-flagellate Naegleria gruberi (Heterolobosea) are encoded on an extrachromosomal circular plasmid. Although the presence of a circular rDNA plasmid in N. gruberi has now been accepted, its sequence and intracellular location are still unclear. We have now sequenced the entire 14,128 bp of the extrachromosomal circular rDNA plasmid. It contains a single rRNA gene unit composed of 18S, 5.8S, and 28S rRNA genes, but no tRNA or 5S RNA genes. We predict that there are two open reading frames. The region that flanks the rRNA gene unit is A/T-rich, except for a highly G/C-rich region that is approximately 900 bp upstream of the rRNA genes. Fluorescence in situ hybridization of N. gruberi cells revealed that the rDNA plasmids cluster within the nucleolus, suggesting that they are highly organized for the efficient transcription of rRNAs. The N. gruberi rDNA plasmid has a unique high-order cluster structure that provides both a molecular basis for understanding chromosomal organization in basal eukaryotes, and a vehicle for constructing stable transgenic vectors.
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MESH Headings
- Animals
- DNA, Ribosomal/analysis
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Genes, rRNA/genetics
- Naegleria/chemistry
- Naegleria/genetics
- Plasmids/genetics
- RNA, Ribosomal, 16S/analysis
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 18S/analysis
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 5.8S/analysis
- RNA, Ribosomal, 5.8S/genetics
- RNA, Ribosomal, 5S/analysis
- RNA, Ribosomal, 5S/genetics
- Sequence Analysis
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Affiliation(s)
- Shinichiro Maruyama
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.
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28
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Pilcher KE, Fey P, Gaudet P, Kowal AS, Chisholm RL. A reliable general purpose method for extracting genomic DNA from Dictyostelium cells. Nat Protoc 2007; 2:1325-8. [PMID: 17545969 DOI: 10.1038/nprot.2007.180] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this protocol, we present a standard method for extracting DNA from cells of the social amoeba Dictyostelium discoideum. While this procedure is similar to other phenol:chloroform-based purification methods, it is modified to account for the high level of carbohydrate and nucleases found in Dictyostelium cells. Genomic DNA can be isolated from wild-type and genetically modified cells using the described protocol, allowing molecular genetic analyses to be performed. Following cell lysis, nucleic acid extraction, and precipitation, the isolated DNA is suitable for digestion by restriction enzymes, amplification by PCR and Southern blotting. This procedure takes approximately 3 h to complete.
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Affiliation(s)
- Karen E Pilcher
- dictyBase, Center for Genetic Medicine, Northwestern University, 676 North Saint Clair Street Suite 1260, Chicago, Illinois 60611, USA
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29
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Romeralo M, Fiz-Palacios O, Lado C, Cavender JC. A new concept for Dictyostelium sphaerocephalum based on morphology and phylogenetic analysis of nuclear ribosomal internal transcribed spacer region sequences. ACTA ACUST UNITED AC 2007. [DOI: 10.1139/b06-147] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Three dictyostelid isolates were found in Spain and Argentina that are morphologically different from known species. These isolates have some features similar to Dictyostelium sphaerocephalum (Oudem.) Sacc., Marchal & É.J. Marchal, but differ in size and sorocarp branching pattern. We sequenced the nuclear ribosomal internal transcribed spacer region to explore phylogenetic relationships among this group of species, including the three new isolates and their closest relatives. In all phylogenetic analyses performed, sequences of all three isolates group together with sequences from “typical” D. sphaerocephalum samples. This result supports previous observations of the morphological plasticity in dictyostelids, especially D. sphaerocephalum, leading us to broaden the classical concept of this species.
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Affiliation(s)
- Maria Romeralo
- Real Jardín Botanico de Madrid, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
| | - Omar Fiz-Palacios
- Real Jardín Botanico de Madrid, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
| | - Carlos Lado
- Real Jardín Botanico de Madrid, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
| | - James C. Cavender
- Real Jardín Botanico de Madrid, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
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30
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El-Halawany MS, Shibata H, Hitomi K, Maki M. Reevaluation of the predicted gene structure of Dictyostelium cystatin A3 (cpiC) by nucleotide sequence determination of its cDNA* and its phylogenetic position in the cystatin superfamily. Mol Biol Rep 2006; 32:257-64. [PMID: 16328887 DOI: 10.1007/s11033-005-3139-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2005] [Indexed: 10/25/2022]
Abstract
Cystatins, cysteine protease inhibitors, are widely distributed among eukaryotes. We reevaluated the structure of the gene cpiC, a gene encoding the third identified member of cystatin family (cystatin A3) that was predicted in the genome database of the social amoeba Dictyostelium discoidium (dictyBase) but remained controversial. We determined the sequences of cDNA and PCR-amplified genomic DNA fragment and found a critical error in the registered nucleotide sequence. The corrected cystatin A3 gene has an open reading frame (ORF) without intron sequence interruption and encodes 94 amino acids (aa), in contrast to the previously predicted sequence of either 80, 82 or 118 aa. The cDNA has an unusual internal poly(A) sequence of 31 adenines, which immediately follows the translation termination codon (TAA) located 146 nucleotides upstream of the post-transcriptional polyadenylation site. The amino acid sequence of Dictyostelium cystatin A3 shows a high similarity to those of previously reported Dictyostelium cystatins as well as Family I cystatins of higher eukaryotes.
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Affiliation(s)
- Medhat S El-Halawany
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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31
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Siol O, Boutliliss M, Chung T, Glöckner G, Dingermann T, Winckler T. Role of RNA polymerase III transcription factors in the selection of integration sites by the dictyostelium non-long terminal repeat retrotransposon TRE5-A. Mol Cell Biol 2006; 26:8242-51. [PMID: 16982688 PMCID: PMC1636787 DOI: 10.1128/mcb.01348-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the compact Dictyostelium discoideum genome, non-long terminal repeat (non-LTR) retrotransposons known as TREs avoid accidental integration-mediated gene disruption by targeting the vicinity of tRNA genes. In this study we provide the first evidence that proteins of a non-LTR retrotransposon interact with a target-specific transcription factor to direct its integration. We applied an in vivo selection system that allows for the isolation of natural TRE5-A integrations into a known genomic location upstream of tRNA genes. TRE5-A frequently modified the integration site in a way characteristic of other non-LTR retrotransposons by adding nontemplated extra nucleotides and generating small and extended target site deletions. Mutations within the B-box promoter of the targeted tRNA genes interfered with both the in vitro binding of RNA polymerase III transcription factor TFIIIC and the ability of TRE5-A to target these genes. An isolated B box was sufficient to enhance TRE5-A integration in the absence of a surrounding tRNA gene. The RNA polymerase III-transcribed ribosomal 5S gene recruits TFIIIC in a B-box-independent manner, yet it was readily targeted by TRE5-A in our assay. These results suggest a direct role of an RNA polymerase III transcription factor in the targeting process.
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Affiliation(s)
- Oliver Siol
- Institut für Pharmazeutische Biologie, Universität Frankfurt/M., Frankfurt, Germany
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32
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Kim YH, Ishikawa D, Ha HP, Sugiyama M, Kaneko Y, Harashima S. Chromosome XII context is important for rDNA function in yeast. Nucleic Acids Res 2006; 34:2914-24. [PMID: 16738130 PMCID: PMC1474064 DOI: 10.1093/nar/gkl293] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2005] [Revised: 09/02/2005] [Accepted: 04/06/2006] [Indexed: 11/13/2022] Open
Abstract
The rDNA cluster in Saccharomyces cerevisiae is located 450 kb from the left end and 610 kb from the right end of chromosome XII and consists of approximately 150 tandemly repeated copies of a 9.1 kb rDNA unit. To explore the biological significance of this specific chromosomal context, chromosome XII was split at both sides of the rDNA cluster and strains harboring deleted variants of chromosome XII consisting of 450 kb, 1500 kb (rDNA cluster only) and 610 kb were created. In the strain harboring the 1500 kb variant of chromosome XII consisting solely of rDNA, the size of the rDNA cluster was found to decrease as a result of a decrease in rDNA copy number. The frequency of silencing of URA3 inserted within the rDNA locus was found to be greater than in a wild-type strain. The localization and morphology of the nucleolus was also affected such that a single and occasionally (6-12% frequency) two foci for Nop1p and a rounded nucleolus were observed, whereas a typical crescent-shaped nucleolar structure was seen in the wild-type strain. Notably, strains harboring the 450 kb chromosome XII variant and/or the 1500 kb variant consisting solely of rDNA had shorter life spans than wild type and also accumulated extrachromosomal rDNA circles. These observations suggest that the context of chromosome XII plays an important role in maintaining a constant rDNA copy number and in physiological processes related to rDNA function in S.cerevisiae.
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Affiliation(s)
- Yeon-Hee Kim
- Department of Biotechnology, Graduate School of Engineering, Osaka University2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Daisuke Ishikawa
- Department of Biotechnology, Graduate School of Engineering, Osaka University2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Ho Phu Ha
- Department of Biotechnology, Graduate School of Engineering, Osaka University2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Minetaka Sugiyama
- Department of Biotechnology, Graduate School of Engineering, Osaka University2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshinobu Kaneko
- Department of Biotechnology, Graduate School of Engineering, Osaka University2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Satoshi Harashima
- Department of Biotechnology, Graduate School of Engineering, Osaka University2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
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33
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Eichinger L, Noegel AA. Comparative genomics of Dictyostelium discoideum and Entamoeba histolytica. Curr Opin Microbiol 2006; 8:606-11. [PMID: 16125444 DOI: 10.1016/j.mib.2005.08.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Accepted: 08/15/2005] [Indexed: 11/18/2022]
Abstract
Amoebozoa represent one of the earliest branches from the last common ancestor of all eukaryotes and contain some of the most dangerous human pathogens. Two amoebozoan genomes -- from the model organism Dictyostelium discoideum and the human pathogen Entamoeba histolytica -- have been published this year. Owing to their high A+T content, both genomes were difficult to sequence. In addition to nine amoebozoan expressed sequence tag projects, efforts are underway for comparative sequencing of four additional Entamoeba species. The completed genome sequences of D. discoideum and E. histolytica revealed unusual telomere structures, a high percentage of repetitive elements and a remarkably high gene content that is close to the one of Drosophila melanogaster. Finally, both organisms are brilliant examples of the influence of the lifestyle of an organism on its genome.
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Affiliation(s)
- Ludwig Eichinger
- Centre for Biochemistry, Medical Faculty, University of Cologne, 50931 Köln, Germany
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34
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Eichinger L, Pachebat J, Glöckner G, Rajandream MA, Sucgang R, Berriman M, Song J, Olsen R, Szafranski K, Xu Q, Tunggal B, Kummerfeld S, Madera M, Konfortov BA, Rivero F, Bankier AT, Lehmann R, Hamlin N, Davies R, Gaudet P, Fey P, Pilcher K, Chen G, Saunders D, Sodergren E, Davis P, Kerhornou A, Nie X, Hall N, Anjard C, Hemphill L, Bason N, Farbrother P, Desany B, Just E, Morio T, Rost R, Churcher C, Cooper J, Haydock S, van Driessche N, Cronin A, Goodhead I, Muzny D, Mourier T, Pain A, Lu M, Harper D, Lindsay R, Hauser H, James K, Quiles M, Babu MM, Saito T, Buchrieser C, Wardroper A, Felder M, Thangavelu M, Johnson D, Knights A, Loulseged H, Mungall K, Oliver K, Price C, Quail M, Urushihara H, Hernandez J, Rabbinowitsch E, Steffen D, Sanders M, Ma J, Kohara Y, Sharp S, Simmonds M, Spiegler S, Tivey A, Sugano S, White B, Walker D, Woodward J, Winckler T, Tanaka Y, Shaulsky G, Schleicher M, Weinstock G, Rosenthal A, Cox E, Chisholm RL, Gibbs R, Loomis WF, Platzer M, Kay RR, Williams J, Dear PH, Noegel AA, Barrell B, Kuspa A. The genome of the social amoeba Dictyostelium discoideum. Nature 2005; 435:43-57. [PMID: 15875012 PMCID: PMC1352341 DOI: 10.1038/nature03481] [Citation(s) in RCA: 947] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Accepted: 02/17/2005] [Indexed: 02/07/2023]
Abstract
The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins, a high proportion of which have long, repetitive amino acid tracts. There are many genes for polyketide synthases and ABC transporters, suggesting an extensive secondary metabolism for producing and exporting small molecules. The genome is rich in complex repeats, one class of which is clustered and may serve as centromeres. Partial copies of the extrachromosomal ribosomal DNA (rDNA) element are found at the ends of each chromosome, suggesting a novel telomere structure and the use of a common mechanism to maintain both the rDNA and chromosomal termini. A proteome-based phylogeny shows that the amoebozoa diverged from the animal-fungal lineage after the plant-animal split, but Dictyostelium seems to have retained more of the diversity of the ancestral genome than have plants, animals or fungi.
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Affiliation(s)
- L. Eichinger
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - J.A. Pachebat
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - G. Glöckner
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - M.-A. Rajandream
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - R. Sucgang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - M. Berriman
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - J. Song
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - R. Olsen
- Section of Cell and Developmental Biology, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - K. Szafranski
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - Q. Xu
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston TX 77030, USA
| | - B. Tunggal
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - S. Kummerfeld
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - M. Madera
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - B. A. Konfortov
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - F. Rivero
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - A. T. Bankier
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - R. Lehmann
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - N. Hamlin
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - R. Davies
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - P. Gaudet
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - P. Fey
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - K. Pilcher
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - G. Chen
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - D. Saunders
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - E. Sodergren
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - P. Davis
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Kerhornou
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - X. Nie
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - N. Hall
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - C. Anjard
- Section of Cell and Developmental Biology, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - L. Hemphill
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - N. Bason
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - P. Farbrother
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - B. Desany
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - E. Just
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - T. Morio
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - R. Rost
- Adolf-Butenandt-Institute/Cell Biology, Ludwig-Maximilians-University, 80336 Munich, Germany
| | - C. Churcher
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - J. Cooper
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - S. Haydock
- Biochemistry Department, University of Cambridge, Cambridge CB2 1QW, UK
| | - N. van Driessche
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - A. Cronin
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - I. Goodhead
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - D. Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - T. Mourier
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Pain
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - M. Lu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - D. Harper
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - R. Lindsay
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
| | - H. Hauser
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - K. James
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - M. Quiles
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - M. Madan Babu
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - T. Saito
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810 Japan
| | - C. Buchrieser
- Unité de Genomique des Microorganismes Pathogenes, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France
| | - A. Wardroper
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
- Department of Biology, University of York, York YO10 5YW, UK
| | - M. Felder
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - M. Thangavelu
- MRC Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 2XZ, UK
| | - D. Johnson
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Knights
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - H. Loulseged
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - K. Mungall
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - K. Oliver
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - C. Price
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - M.A. Quail
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - H. Urushihara
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - J. Hernandez
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - E. Rabbinowitsch
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - D. Steffen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - M. Sanders
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - J. Ma
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Y. Kohara
- Centre for Genetic Resource Information, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - S. Sharp
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - M. Simmonds
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - S. Spiegler
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Tivey
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - S. Sugano
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Minato, Tokyo 108-8639, Japan
| | - B. White
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - D. Walker
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - J. Woodward
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - T. Winckler
- Institut für Pharmazeutische Biologie, Universität Frankfurt (Biozentrum), Frankfurt am Main, 60439, Germany
| | - Y. Tanaka
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - G. Shaulsky
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston TX 77030, USA
| | - M. Schleicher
- Adolf-Butenandt-Institute/Cell Biology, Ludwig-Maximilians-University, 80336 Munich, Germany
| | - G. Weinstock
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - A. Rosenthal
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - E.C. Cox
- Department of Molecular Biology, Princeton University, Princeton, NJ08544-1003, USA
| | - R. L. Chisholm
- dictyBase, Center for Genetic Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611, USA
| | - R. Gibbs
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - W. F. Loomis
- Section of Cell and Developmental Biology, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - M. Platzer
- Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstr. 11, D-07745 Jena, Germany
| | - R. R. Kay
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - J. Williams
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - P. H. Dear
- Laboratory of Molecular Biology, MRC Centre, Cambridge CB2 2QH, UK
| | - A. A. Noegel
- Center for Biochemistry and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - B. Barrell
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK
| | - A. Kuspa
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030, USA
- Dept. of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Aspegren A, Hinas A, Larsson P, Larsson A, Söderbom F. Novel non-coding RNAs in Dictyostelium discoideum and their expression during development. Nucleic Acids Res 2004; 32:4646-56. [PMID: 15333696 PMCID: PMC516072 DOI: 10.1093/nar/gkh804] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The quest for non-coding RNAs (ncRNAs) in the last few years has revealed a surprisingly large number of small RNAs belonging to previously known as well as entirely novel classes. Computational and experimental approaches have uncovered new ncRNAs in all kingdoms of life. In this work, we used a shotgun cloning approach to construct full-length cDNA libraries of small RNAs from the eukaryotic model organism Dictyostelium discoideum. Interestingly, two entirely novel classes of RNAs were identified of which one is developmentally regulated. The RNAs within each class share conserved 5'- and 3'-termini that can potentially form stem structures. RNAs of both classes show predominantly cytoplasmic localization. In addition, based on conserved structure and/or sequence motifs, several of the identified ncRNAs could be divided into classes known from other organisms, e.g. 18 small nucleolar RNA candidates (17 box C/D, of which a few are developmentally regulated, and one box H/ACA). Two ncRNAs showed a high degree of similarity to the small nuclear U2 RNA and signal recognition particle RNA (SRP RNA), respectively. Furthermore, the majority of the regions upstream of the sequences encoding the isolated RNAs share conserved motifs that may constitute new promoter elements.
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Affiliation(s)
- Anders Aspegren
- Department of Molecular Biology, Biomedical Center, Swedish University of Agricultural Sciences, Box 590, S-75124 Uppsala, Sweden
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Wickstead B, Ersfeld K, Gull K. The small chromosomes of Trypanosoma brucei involved in antigenic variation are constructed around repetitive palindromes. Genome Res 2004; 14:1014-24. [PMID: 15173109 PMCID: PMC419779 DOI: 10.1101/gr.2227704] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Accepted: 02/12/2004] [Indexed: 01/09/2023]
Abstract
Most eukaryotic genomes contain large regions of satellite DNA. These arrays are often associated with essential chromosomal functions, but remain largely absent from genome projects because of difficulties in cloning and sequence assembly. The numerous small chromosomes of the parasite Trypanosoma brucei fall into this category, yet are critical to understanding the genome because of their role in antigenic variation. Their relatively small size, however, makes them particularly amenable to physical mapping. We have produced fine-resolution maps of 17 complete minichromosomes and partial maps of two larger intermediate-sized chromosomes. This revealed a canonical structure shared by both chromosomal classes based around a large central core of 177-bp repeats. Around the core are variable-length genic regions, the lengths of which define chromosomal class. We show the core region to be a repetitive palindrome with a single inversion point common to all the chromosomes of both classes, suggesting a mechanism of genesis for these chromosomes. Moreover, palindromy appears to be a feature of (peri)centromeres in other species that can be easily overlooked. We propose that sequence inversion is one of the higher-order sequence motifs that confer chromosomal stability.
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Affiliation(s)
- Bill Wickstead
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom
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Chen G, Shaulsky G, Kuspa A. Tissue-specific G1-phase cell-cycle arrest prior to terminal differentiation in Dictyostelium. Development 2004; 131:2619-30. [PMID: 15128662 DOI: 10.1242/dev.01151] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cell cycle status of developing Dictyostelium cells remains unresolved because previous studies have led to conflicting interpretations. We propose a new model of cell cycle events during development. We observe mitosis of about 50% of the cells between 12 and 18 hours of development. Cellular DNA content profiles obtained by flow cytometry and quantification of extra-chromosomal and chromosomal DNA suggest that the daughter cells have half the chromosomal DNA of vegetative cells. Furthermore, little chromosomal DNA synthesis occurs during development, indicating that no S phase occurs. The DNA content in cells sorted by fluorescent tissue-specific reporters indicates that prespore cells divide before prestalk cells and later encapsulate as G1-arrested spores. Consistent with this, germinating spores have one copy of their chromosomes, as judged by fluorescence in situ hybridization and they replicate their chromosomes before mitosis of the emergent amoebae. The DNA content of mature stalk cells suggests that they also attain a G1 state prior to terminal differentiation. As prestalk cells appear to be in G2 up to 22 hours of development, our data suggest that they divide just prior to stalk formation. Our results suggest tissue-specific regulation of G1 phase cell cycle arrest prior to terminal differentiation in Dictyostelium.
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Affiliation(s)
- Guokai Chen
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Szafranski K, Dingermann T, Glöckner G, Winckler T. Template jumping by a LINE reverse transcriptase has created a SINE-like 5S rRNA retropseudogene in Dictyostelium. Mol Genet Genomics 2003; 271:98-102. [PMID: 14652739 DOI: 10.1007/s00438-003-0961-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2003] [Accepted: 11/10/2003] [Indexed: 11/27/2022]
Abstract
Short interspersed nuclear elements (SINEs) are non-autonomous retroelements that mimic the 3' ends of so-called long interspersed nuclear elements (LINEs) to ensure their propagation by proteins encoded by autonomous LINEs. The Dictyostelium discoideum genome contains a family of LINE-like retrotransposons that specifically target tRNA genes for integration (TRE elements). We describe here a retrotransposed ribosomal 5S RNA pseudogene in the D. discoideum genome that contains at its 3' end an 8-bp sequence derived from the 3' end of a TRE and a polyadenine tail. The r5S "retropseudogene" is flanked by target-site duplications that are characteristic for TREs, and is inserted upstream of a tRNA gene, just like a typical TRE. The D. discoideum r5S retropseudogene has structural features of a SINE, but has not been amplified, probably due to the 5'-truncation that occurred upon its initial retrotransposition. The discovery of this D. discoideum r5S retropseudogene reveals that SINEs can be created de novo during reverse transcription of LINE transcripts, if the LINE-encoded reverse transcriptase dissociates from the LINE RNA and jumps to other cellular RNAs-particularly genes transcribed by RNA polymerase III-to create continuous mixed cDNAs.
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Affiliation(s)
- K Szafranski
- Department of Genome Analysis, IMB Jena, Beutenbergstrasse 11, 07745 Jena, Germany
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Eichinger L. Revamp a model-status and prospects of the Dictyostelium genome project. Curr Genet 2003; 44:59-72. [PMID: 12856150 DOI: 10.1007/s00294-003-0416-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2003] [Revised: 06/04/2003] [Accepted: 06/05/2003] [Indexed: 10/26/2022]
Abstract
International efforts are underway that aim at determining the complete genome sequence of the social amoeba Dictyostelium discoideum. As strategy, a whole chromosome shotgun (WCS) approach was chosen and each of the six Dictyostelium chromosomes was assigned to project partners. The project is well advanced, chromosome 2 was recently published, and it is expected that the sequences of chromosomes 1 and 6 and a gene catalogue for the complete genome will be available at the end of this year. The genome sequence, together with powerful molecular genetic tools, will undoubtedly further accelerate Dictyostelium research into a number of fundamental biological processes that are common to a wide range of eukaryotes. Furthermore, it will constitute the basis for genome-wide functional analyses. The integration of results from these studies should ultimately lead to a better understanding of the complex networks that govern cellular behavior and development.
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Affiliation(s)
- Ludwig Eichinger
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Strasse 52, 50931, Köln, Germany.
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King J, Insall RH. Parasexual genetics of Dictyostelium gene disruptions: identification of a ras pathway using diploids. BMC Genet 2003; 4:12. [PMID: 12854977 PMCID: PMC183827 DOI: 10.1186/1471-2156-4-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2003] [Accepted: 07/10/2003] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND The relative ease of targeted gene disruption in the social amoeba Dictyostelium has stimulated its widespread use as an experimental organism for cell and developmental biology. However, the field has been hamstrung by the lack of techniques to recombine disrupted genes. RESULTS We describe new techniques for parasexual fusion of strains in liquid medium, selection and maintenance of the resulting stable diploid strains, and segregation to make recombined haploids. We have used these techniques to isolate rasS/gefB double nulls. The phenotypes of these mutants are no more severe than either parent, with movement, phagocytosis and fluid-phase endocytosis affected to the same degree as in rasS or gefB single nulls. In addition, we have produced diploids from one AX2- and one AX3-derived parent, providing an axenic strain with fewer secondary phenotypes than has been previously available. CONCLUSIONS The phenotype of the rasS/gefB double mutant suggests that the RasS and GefB proteins lie on the same linear pathway. In addition, axenic diploids and the techniques to generate, maintain and segregate them will be productive tools for future work on Dictyostelium. They will particularly facilitate generation of multiple mutants and manipulation of essential genes.
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Affiliation(s)
- Jason King
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Robert H Insall
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
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