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Boscaro V, James ER, Fiorito R, Del Campo J, Scheffrahn RH, Keeling PJ. Updated classification of the phylum Parabasalia. J Eukaryot Microbiol 2024; 71:e13035. [PMID: 38825738 DOI: 10.1111/jeu.13035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/13/2024] [Accepted: 05/15/2024] [Indexed: 06/04/2024]
Abstract
The phylum Parabasalia includes very diverse single-cell organisms that nevertheless share a distinctive set of morphological traits. Most are harmless or beneficial gut symbionts of animals, but some have turned into parasites in other body compartments, the most notorious example being Trichomonas vaginalis in humans. Parabasalians have garnered attention for their nutritional symbioses with termites, their modified anaerobic mitochondria (hydrogenosomes), their character evolution, and the wholly unique features of some species. The molecular revolution confirmed the monophyly of Parabasalia, but considerably changed our view of their internal relationships, prompting a comprehensive reclassification 14 years ago. This classification has remained authoritative for many subgroups despite a greatly expanded pool of available data, but the large number of species and sequences that have since come out allow for taxonomic refinements in certain lineages, which we undertake here. We aimed to introduce as little disruption as possible but at the same time ensure that most taxa are truly monophyletic, and that the larger clades are subdivided into meaningful units. In doing so, we also highlighted correlations between the phylogeny of parabasalians and that of their hosts.
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Affiliation(s)
- Vittorio Boscaro
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Erick R James
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Rebecca Fiorito
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Javier Del Campo
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- Institut de Biologia Evolutiva, CSIC-Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | | | - Patrick J Keeling
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
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2
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Tachezy J, Makki A, Hrdý I. The hydrogenosomes of Trichomonas vaginalis. J Eukaryot Microbiol 2022; 69:e12922. [PMID: 35567536 DOI: 10.1111/jeu.12922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This review is dedicated to the 50th anniversary of the discovery of hydrogenosomes by Miklós Müller and Donald Lindmark, which we will celebrate the following year. It was a long journey from the first observation of enigmatic rows of granules in trichomonads at the end of the 19th century to their first biochemical characterization in 1973. The key experiments by Müller and Lindmark revealed that the isolated granules contain hydrogen-producing hydrogenase, similar to some anaerobic bacteria-a discovery that gave birth to the field of hydrogenosomes. It is also important to acknowledge the parallel work of the team of Apolena Čerkasovová, Jiří Čerkasov, and Jaroslav Kulda, who demonstrated that these granules, similar to mitochondria, produce ATP. However, the evolutionary origin of hydrogenosomes remained enigmatic until the turn of the millennium, when it was finally accepted that hydrogenosomes and mitochondria evolved from a common ancestor. After a historical introduction, the review provides an overview of hydrogenosome biogenesis, hydrogenosomal protein import, and the relationship between the peculiar structure of membrane translocases and its low inner membrane potential due to the lack of respiratory complexes. Next, it summarizes the current state of knowledge on energy metabolism, the oxygen defense system, and iron/sulfur cluster assembly.
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Affiliation(s)
- Jan Tachezy
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, 25242 Vestec, Czech Republic
| | - Abhijith Makki
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, 25242 Vestec, Czech Republic
| | - Ivan Hrdý
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, 25242 Vestec, Czech Republic
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3
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Jespersen N, Monrroy L, Barandun J. Impact of Genome Reduction in Microsporidia. EXPERIENTIA SUPPLEMENTUM (2012) 2022; 114:1-42. [PMID: 35543997 DOI: 10.1007/978-3-030-93306-7_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Microsporidia represent an evolutionary outlier in the tree of life and occupy the extreme edge of the eukaryotic domain with some of their biological features. Many of these unicellular fungi-like organisms have reduced their genomic content to potentially the lowest limit. With some of the most compacted eukaryotic genomes, microsporidia are excellent model organisms to study reductive evolution and its functional consequences. While the growing number of sequenced microsporidian genomes have elucidated genome composition and organization, a recent increase in complementary post-genomic studies has started to shed light on the impacts of genome reduction in these unique pathogens. This chapter will discuss the biological framework enabling genome minimization and will use one of the most ancient and essential macromolecular complexes, the ribosome, to illustrate the effects of extreme genome reduction on a structural, molecular, and cellular level. We outline how reductive evolution in microsporidia has shaped DNA organization, the composition and function of the ribosome, and the complexity of the ribosome biogenesis process. Studying compacted mechanisms, processes, or macromolecular machines in microsporidia illuminates their unique lifestyle and provides valuable insights for comparative eukaryotic structural biology.
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Affiliation(s)
- Nathan Jespersen
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden.
| | - Leonardo Monrroy
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden
| | - Jonas Barandun
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden.
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4
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Waters ER, Vierling E. Plant small heat shock proteins - evolutionary and functional diversity. THE NEW PHYTOLOGIST 2020; 227:24-37. [PMID: 32297991 DOI: 10.1111/nph.16536] [Citation(s) in RCA: 113] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 02/21/2020] [Indexed: 05/22/2023]
Abstract
Small heat shock proteins (sHSPs) are an ubiquitous protein family found in archaea, bacteria and eukaryotes. In plants, as in other organisms, sHSPs are upregulated by stress and are proposed to act as molecular chaperones to protect other proteins from stress-induced damage. sHSPs share an 'α-crystallin domain' with a β-sandwich structure and a diverse N-terminal domain. Although sHSPs are 12-25 kDa polypeptides, most assemble into oligomers with ≥ 12 subunits. Plant sHSPs are particularly diverse and numerous; some species have as many as 40 sHSPs. In angiosperms this diversity comprises ≥ 11 sHSP classes encoding proteins targeted to the cytosol, nucleus, endoplasmic reticulum, chloroplasts, mitochondria and peroxisomes. The sHSPs underwent a lineage-specific gene expansion, diversifying early in land plant evolution, potentially in response to stress in the terrestrial environment, and expanded again in seed plants and again in angiosperms. Understanding the structure and evolution of plant sHSPs has progressed, and a model for their chaperone activity has been proposed. However, how the chaperone model applies to diverse sHSPs and what processes sHSPs protect are far from understood. As more plant genomes and transcriptomes become available, it will be possible to explore theories of the evolutionary pressures driving sHSP diversification.
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Affiliation(s)
- Elizabeth R Waters
- Biology Department, San Diego State University, San Diego, CA, 92182, USA
| | - Elizabeth Vierling
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
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Verdaguer IB, Zafra CA, Crispim M, Sussmann RA, Kimura EA, Katzin AM. Prenylquinones in Human Parasitic Protozoa: Biosynthesis, Physiological Functions, and Potential as Chemotherapeutic Targets. Molecules 2019; 24:molecules24203721. [PMID: 31623105 PMCID: PMC6832408 DOI: 10.3390/molecules24203721] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 09/25/2019] [Accepted: 10/01/2019] [Indexed: 12/19/2022] Open
Abstract
Human parasitic protozoa cause a large number of diseases worldwide and, for some of these diseases, there are no effective treatments to date, and drug resistance has been observed. For these reasons, the discovery of new etiological treatments is necessary. In this sense, parasitic metabolic pathways that are absent in vertebrate hosts would be interesting research candidates for the identification of new drug targets. Most likely due to the protozoa variability, uncertain phylogenetic origin, endosymbiotic events, and evolutionary pressure for adaptation to adverse environments, a surprising variety of prenylquinones can be found within these organisms. These compounds are involved in essential metabolic reactions in organisms, for example, prevention of lipoperoxidation, participation in the mitochondrial respiratory chain or as enzymatic cofactors. This review will describe several prenylquinones that have been previously characterized in human pathogenic protozoa. Among all existing prenylquinones, this review is focused on ubiquinone, menaquinone, tocopherols, chlorobiumquinone, and thermoplasmaquinone. This review will also discuss the biosynthesis of prenylquinones, starting from the isoprenic side chains to the aromatic head group precursors. The isoprenic side chain biosynthesis maybe come from mevalonate or non-mevalonate pathways as well as leucine dependent pathways for isoprenoid biosynthesis. Finally, the isoprenic chains elongation and prenylquinone aromatic precursors origins from amino acid degradation or the shikimate pathway is reviewed. The phylogenetic distribution and what is known about the biological functions of these compounds among species will be described, as will the therapeutic strategies associated with prenylquinone metabolism in protozoan parasites.
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Affiliation(s)
- Ignasi B. Verdaguer
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
| | - Camila A. Zafra
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
| | - Marcell Crispim
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
| | - Rodrigo A.C. Sussmann
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
- Centro de Formação em Ciências Ambientais, Universidade Federal do Sul da Bahia, Porto Seguro 45810-000 Bahia, Brazil
| | - Emília A. Kimura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
| | - Alejandro M. Katzin
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
- Correspondence: ; Tel.: +55-11-3091-7330; Fax: +5511-3091-7417
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6
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Martin WF, Tielens AGM, Mentel M, Garg SG, Gould SB. The Physiology of Phagocytosis in the Context of Mitochondrial Origin. Microbiol Mol Biol Rev 2017; 81:e00008-17. [PMID: 28615286 PMCID: PMC5584316 DOI: 10.1128/mmbr.00008-17] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
How mitochondria came to reside within the cytosol of their host has been debated for 50 years. Though current data indicate that the last eukaryote common ancestor possessed mitochondria and was a complex cell, whether mitochondria or complexity came first in eukaryotic evolution is still discussed. In autogenous models (complexity first), the origin of phagocytosis poses the limiting step at eukaryote origin, with mitochondria coming late as an undigested growth substrate. In symbiosis-based models (mitochondria first), the host was an archaeon, and the origin of mitochondria was the limiting step at eukaryote origin, with mitochondria providing bacterial genes, ATP synthesis on internalized bioenergetic membranes, and mitochondrion-derived vesicles as the seed of the eukaryote endomembrane system. Metagenomic studies are uncovering new host-related archaeal lineages that are reported as complex or phagocytosing, although images of such cells are lacking. Here we review the physiology and components of phagocytosis in eukaryotes, critically inspecting the concept of a phagotrophic host. From ATP supply and demand, a mitochondrion-lacking phagotrophic archaeal fermenter would have to ingest about 34 times its body weight in prokaryotic prey to obtain enough ATP to support one cell division. It would lack chemiosmotic ATP synthesis at the plasma membrane, because phagocytosis and chemiosmosis in the same membrane are incompatible. It would have lived from amino acid fermentations, because prokaryotes are mainly protein. Its ATP yield would have been impaired relative to typical archaeal amino acid fermentations, which involve chemiosmosis. In contrast, phagocytosis would have had great physiological benefit for a mitochondrion-bearing cell.
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Affiliation(s)
- William F Martin
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Aloysius G M Tielens
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Marek Mentel
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Sriram G Garg
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sven B Gould
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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7
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Sequence analysis of the Hsp70 family in moss and evaluation of their functions in abiotic stress responses. Sci Rep 2016; 6:33650. [PMID: 27644410 PMCID: PMC5028893 DOI: 10.1038/srep33650] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/31/2016] [Indexed: 11/30/2022] Open
Abstract
The 70-kD heat shock proteins (Hsp70s) are highly conserved molecular chaperones that play essential roles in cellular processes including abiotic stress responses. Physcomitrella patens serves as a representative of the first terrestrial plants and can recover from serious dehydration. To assess the possible relationship between P. patens Hsp70s and dehydration tolerance, we analyzed the P. patens genome and found at least 21 genes encoding Hsp70s. Gene structure and motif composition were relatively conserved in each subfamily. The intron-exon structure of PpcpHsp70-2 was different from that of other PpcpHsp70s; this gene exhibits several forms of intron retention, indicating that introns may play important roles in regulating gene expression. We observed expansion of Hsp70s in P. patens, which may reflect adaptations related to development and dehydration tolerance, and results mainly from tandem and segmental duplications. Expression profiles of rice, Arabidopsis and P. patens Hsp70 genes revealed that more than half of the Hsp70 genes were responsive to ABA, salt and drought. The presence of overrepresented cis-elements (DOFCOREZM and GCCCORE) among stress-responsive Hsp70s suggests that they share a common regulatory pathway. Moss plants overexpressing PpcpHsp70-2 showed salt and dehydration tolerance, further supporting a role in adaptation to land. This work highlights directions for future functional analyses of Hsp70s.
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8
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Stairs CW, Leger MM, Roger AJ. Diversity and origins of anaerobic metabolism in mitochondria and related organelles. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140326. [PMID: 26323757 PMCID: PMC4571565 DOI: 10.1098/rstb.2014.0326] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2015] [Indexed: 12/27/2022] Open
Abstract
Across the diversity of life, organisms have evolved different strategies to thrive in hypoxic environments, and microbial eukaryotes (protists) are no exception. Protists that experience hypoxia often possess metabolically distinct mitochondria called mitochondrion-related organelles (MROs). While there are some common metabolic features shared between the MROs of distantly related protists, these organelles have evolved independently multiple times across the breadth of eukaryotic diversity. Until recently, much of our knowledge regarding the metabolic potential of different MROs was limited to studies in parasitic lineages. Over the past decade, deep-sequencing studies of free-living anaerobic protists have revealed novel configurations of metabolic pathways that have been co-opted for life in low oxygen environments. Here, we provide recent examples of anaerobic metabolism in the MROs of free-living protists and their parasitic relatives. Additionally, we outline evolutionary scenarios to explain the origins of these anaerobic pathways in eukaryotes.
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Affiliation(s)
- Courtney W Stairs
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, PO Box 15000, Halifax, Nova Scotia, Canada B3H 4R2
| | - Michelle M Leger
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, PO Box 15000, Halifax, Nova Scotia, Canada B3H 4R2
| | - Andrew J Roger
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, PO Box 15000, Halifax, Nova Scotia, Canada B3H 4R2
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9
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Highly divergent mitochondrion-related organelles in anaerobic parasitic protozoa. Biochimie 2014; 100:3-17. [DOI: 10.1016/j.biochi.2013.11.018] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 11/24/2013] [Indexed: 11/20/2022]
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10
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Liu S, Wang J, Cong B, Huang X, Chen K, Zhang P. Characterization and expression analysis of a mitochondrial heat-shock protein 70 gene from the Antarctic moss Pohlia nutans. Polar Biol 2014. [DOI: 10.1007/s00300-014-1508-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Early evolution of eukaryote feeding modes, cell structural diversity, and classification of the protozoan phyla Loukozoa, Sulcozoa, and Choanozoa. Eur J Protistol 2012; 49:115-78. [PMID: 23085100 DOI: 10.1016/j.ejop.2012.06.001] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 06/21/2012] [Accepted: 06/26/2012] [Indexed: 11/21/2022]
Abstract
I discuss how different feeding modes and related cellular structures map onto the eukaryote evolutionary tree. Centrally important for understanding eukaryotic cell diversity are Loukozoa: ancestrally biciliate phagotrophic protozoa possessing a posterior cilium and ventral feeding groove into which ciliary currents direct prey. I revise their classification by including all anaerobic Metamonada as a subphylum and adding Tsukubamonas. Loukozoa, often with ciliary vanes, are probably ancestral to all protozoan phyla except Euglenozoa and Percolozoa and indirectly to kingdoms Animalia, Fungi, Plantae, and Chromista. I make a new protozoan phylum Sulcozoa comprising subphyla Apusozoa (Apusomonadida, Breviatea) and Varisulca (Diphyllatea; Planomonadida, Discocelida, Mantamonadida; Rigifilida). Understanding sulcozoan evolution clarifies the origins from them of opisthokonts (animals, fungi, Choanozoa) and Amoebozoa, and their evolutionary novelties; Sulcozoa and their descendants (collectively called podiates) arguably arose from Loukozoa by evolving posterior ciliary gliding and pseudopodia in their ventral groove. I explain subsequent independent cytoskeletal modifications, accompanying further shifts in feeding mode, that generated Amoebozoa, Choanozoa, and fungi. I revise classifications of Choanozoa, Conosa (Amoebozoa), and basal fungal phylum Archemycota. I use Choanozoa, Sulcozoa, Loukozoa, and Archemycota to emphasize the need for simply classifying ancestral (paraphyletic) groups and illustrate advantages of this for understanding step-wise phylogenetic advances.
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Müller M, Mentel M, van Hellemond JJ, Henze K, Woehle C, Gould SB, Yu RY, van der Giezen M, Tielens AGM, Martin WF. Biochemistry and evolution of anaerobic energy metabolism in eukaryotes. Microbiol Mol Biol Rev 2012; 76:444-95. [PMID: 22688819 PMCID: PMC3372258 DOI: 10.1128/mmbr.05024-11] [Citation(s) in RCA: 505] [Impact Index Per Article: 42.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Major insights into the phylogenetic distribution, biochemistry, and evolutionary significance of organelles involved in ATP synthesis (energy metabolism) in eukaryotes that thrive in anaerobic environments for all or part of their life cycles have accrued in recent years. All known eukaryotic groups possess an organelle of mitochondrial origin, mapping the origin of mitochondria to the eukaryotic common ancestor, and genome sequence data are rapidly accumulating for eukaryotes that possess anaerobic mitochondria, hydrogenosomes, or mitosomes. Here we review the available biochemical data on the enzymes and pathways that eukaryotes use in anaerobic energy metabolism and summarize the metabolic end products that they generate in their anaerobic habitats, focusing on the biochemical roles that their mitochondria play in anaerobic ATP synthesis. We present metabolic maps of compartmentalized energy metabolism for 16 well-studied species. There are currently no enzymes of core anaerobic energy metabolism that are specific to any of the six eukaryotic supergroup lineages; genes present in one supergroup are also found in at least one other supergroup. The gene distribution across lineages thus reflects the presence of anaerobic energy metabolism in the eukaryote common ancestor and differential loss during the specialization of some lineages to oxic niches, just as oxphos capabilities have been differentially lost in specialization to anoxic niches and the parasitic life-style. Some facultative anaerobes have retained both aerobic and anaerobic pathways. Diversified eukaryotic lineages have retained the same enzymes of anaerobic ATP synthesis, in line with geochemical data indicating low environmental oxygen levels while eukaryotes arose and diversified.
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Affiliation(s)
| | - Marek Mentel
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Jaap J. van Hellemond
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Katrin Henze
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
| | - Christian Woehle
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
| | - Sven B. Gould
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
| | - Re-Young Yu
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
| | - Mark van der Giezen
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Aloysius G. M. Tielens
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, Netherlands
| | - William F. Martin
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
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13
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Desmond E, Brochier-Armanet C, Forterre P, Gribaldo S. On the last common ancestor and early evolution of eukaryotes: reconstructing the history of mitochondrial ribosomes. Res Microbiol 2011; 162:53-70. [DOI: 10.1016/j.resmic.2010.10.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 10/04/2010] [Indexed: 12/31/2022]
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14
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Abstract
The discovery of mitochondrion-type genes in organisms thought to lack mitochondria led to the demonstration that hydrogenosomes share a common ancestry with mitochondria, as well as the discovery of mitosomes in multiple eukaryotic lineages. No examples of examined eukaryotes lacking a mitochondrion-related organelle exist, implying that the endosymbiont that gave rise to the mitochondrion was present in the first eukaryote. These organelles, known as hydrogenosomes, mitosomes, or mitochondrion-like organelles, are typically reduced, both structurally and biochemically, relative to classical mitochondria. However, despite their diversification and adaptation to different niches, all appear to play a role in Fe-S cluster assembly, as observed for mitochondria. Although evidence supports the use of common protein targeting mechanisms in the biogenesis of these diverse organelles, divergent features are also apparent. This review examines the metabolism and biogenesis of these organelles in divergent unicellular microbes, with a focus on parasitic protists.
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Affiliation(s)
- April M Shiflett
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095-1489, USA
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15
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O'Malley MA. The first eukaryote cell: an unfinished history of contestation. STUDIES IN HISTORY AND PHILOSOPHY OF BIOLOGICAL AND BIOMEDICAL SCIENCES 2010; 41:212-224. [PMID: 20934642 DOI: 10.1016/j.shpsc.2010.07.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The eukaryote cell is one of the most radical innovations in the history of life, and the circumstances of its emergence are still deeply contested. This paper will outline the recent history of attempts to reveal these origins, with special attention to the argumentative strategies used to support claims about the first eukaryote cell. I will focus on two general models of eukaryogenesis: the phagotrophy model and the syntrophy model. As their labels indicate, they are based on claims about metabolic relationships. The first foregrounds the ability to consume other organisms; the second the ability to enter into symbiotic metabolic arrangements. More importantly, however, the first model argues for the autogenous or self-generated origins of the eukaryote cell, and the second for its exogenous or externally generated origins. Framing cell evolution this way leads each model to assert different priorities in regard to cell-biological versus molecular evidence, cellular versus environmental influences, plausibility versus evolutionary probability, and irreducibility versus the continuity of cell types. My examination of these issues will conclude with broader reflections on the implications of eukaryogenesis studies for a philosophical understanding of scientific contestation.
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Affiliation(s)
- Maureen A O'Malley
- ESRC Research Centre for Genomics in Society (Egenis), University of Exeter, Byrne House, St. Germans Road, Exeter EX4 4PJ, UK. M.A.O’
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16
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Tielens AGM, van Grinsven KWA, Henze K, van Hellemond JJ, Martin W. Acetate formation in the energy metabolism of parasitic helminths and protists. Int J Parasitol 2010; 40:387-97. [PMID: 20085767 DOI: 10.1016/j.ijpara.2009.12.006] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 12/08/2009] [Accepted: 12/09/2009] [Indexed: 10/19/2022]
Abstract
Formation and excretion of acetate as a metabolic end product of energy metabolism occurs in many protist and helminth parasites, such as the parasitic helminths Fasciola hepatica, Haemonchus contortus and Ascaris suum, and the protist parasites, Giardia lamblia, Entamoeba histolytica, Trichomonas vaginalis as well as Trypanosoma and Leishmania spp. In all of these parasites acetate is a main end product of their energy metabolism, whereas acetate formation does not occur in their mammalian hosts. Acetate production might therefore harbour novel targets for the development of new anti-parasitic drugs. In parasites, acetate is produced from acetyl-CoA by two different reactions, both involving substrate level phosphorylation, that are catalysed by either a cytosolic acetyl-CoA synthetase (ACS) or an organellar acetate:succinate CoA-transferase (ASCT). The ACS reaction is directly coupled to ATP synthesis, whereas the ASCT reaction yields succinyl-CoA for ATP formation via succinyl-CoA synthetase (SCS). Based on recent work on the ASCTs of F. hepatica, T. vaginalis and Trypanosoma brucei we suggest the existence of three subfamilies of enzymes within the CoA-transferase family I. Enzymes of these three subfamilies catalyse the ASCT reaction in eukaryotes via the same mechanism, but the subfamilies share little sequence homology. The CoA-transferases of the three subfamilies are all present inside ATP-producing organelles of parasites, those of subfamily IA in the mitochondria of trypanosomatids, subfamily IB in the mitochondria of parasitic worms and subfamily IC in hydrogenosome-bearing parasites. Together with the recent characterisation among non-parasitic protists of yet a third route of acetate formation involving acetate kinase (ACK) and phosphotransacetylase (PTA) that was previously unknown among eukaryotes, these recent developments provide a good opportunity to have a closer look at eukaryotic acetate formation.
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Affiliation(s)
- Aloysius G M Tielens
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, 's Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands.
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Hug LA, Stechmann A, Roger AJ. Phylogenetic Distributions and Histories of Proteins Involved in Anaerobic Pyruvate Metabolism in Eukaryotes. Mol Biol Evol 2009; 27:311-24. [DOI: 10.1093/molbev/msp237] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Affiliation(s)
- Patrick Keeling
- Botany Department, Canadian Institute for Advanced Research, University of British Columbia, Vancouver, British Columbia, Canada.
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19
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Benchimol M. Hydrogenosomes under microscopy. Tissue Cell 2009; 41:151-68. [PMID: 19297000 DOI: 10.1016/j.tice.2009.01.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Revised: 01/04/2009] [Accepted: 01/13/2009] [Indexed: 11/19/2022]
Abstract
A hydrogenosome is a hydrogen-producing organelle, evolutionary related to mitochondria and is found in Parabasalia protozoa, certain chytrid fungi and certain ciliates. It displays similarities to and differences from mitochondria. Hydrogenosomes are spherical or slightly elongated organelles, although very elongated hydrogenosomes are also found. They measure from 200 nm to 1 microm, but under stress conditions can reach up to 2 microm. Hydrogenosomes are surrounded by two closely apposed membranes and present a granular matrix. Cardiolipin has been detected in their membranes, and frataxin, which is a conserved mitochondrial protein involved in iron metabolism, was also recently found. Hydrogenosomes have one or multiple peripheral vesicles, which incorporate calcium. The peripheral vesicle can be isolated from the hydrogenosomal matrix and can be considered as a distinct hydrogenosomal compartment. Dysfunctional hydrogenosomes can be removed by an autophagic process and further digested by lysosomes. Hydrogenosomes divide in three different ways, like mitochondria, by segmentation, partition and the heart form. They may divide at any phase of the cell cycle. Nucleoid or electron dense deposits found in hydrogenosomes can be considered artifacts or dysfunctional hydrogenosomes. The hydrogenosome does not contain a genome, although DNA has already been detected in one anaerobic ciliate. Hydrogenosomes can be considered as good drug targets since their metabolism is distinct from mitochondria.
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Affiliation(s)
- Marlene Benchimol
- Universidade Santa Ursula, Laboratório de Ultraestrutura Celular, Rio de Janeiro, Brazil.
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VAN DER GIEZEN MARK. Hydrogenosomes and Mitosomes: Conservation and Evolution of Functions. J Eukaryot Microbiol 2009; 56:221-31. [DOI: 10.1111/j.1550-7408.2009.00407.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Identification of microRNA in the protist Trichomonas vaginalis. Genomics 2009; 93:487-93. [PMID: 19442639 DOI: 10.1016/j.ygeno.2009.01.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 12/31/2008] [Accepted: 01/17/2009] [Indexed: 01/11/2023]
Abstract
MicroRNAs (miRNAs) are a class of small noncoding RNAs that have important regulatory roles in multicellular organisms. However, miRNA has never been identified experimentally in protist. Direct cloning of 438 expressed miRNA tags by microRNA serial analysis of gene expression from the parasitic protist Trichomonas vaginalis identified nine candidate miRNAs. Bioinformatics analysis of the corresponding genomic region revealed that these miRNA candidates contain a classical stem-loop-stem structure of pre-microRNAs. Analysis of the 20 nt long mature tva-miR-001 showed that it is an intergenic miRNA located at the scaffold DS113596. Tva-miR-001 was differentially expressed in the trophozoite, pseudocyst and amoeboid stages. Based on the experimental results of the present study, we provided solid evidence that protist possesses a miRNA regulating network comparable with multicellular organisms for the first time.
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Gaston D, Tsaousis AD, Roger AJ. Predicting proteomes of mitochondria and related organelles from genomic and expressed sequence tag data. Methods Enzymol 2009; 457:21-47. [PMID: 19426860 DOI: 10.1016/s0076-6879(09)05002-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In eukaryotes, determination of the subcellular location of a novel protein encoded in genomic or transcriptomic data provides useful clues as to its possible function. However, experimental localization studies are expensive and time-consuming. As a result, accurate in silico prediction of subcellular localization from sequence data alone is an extremely important field of study in bioinformatics. This is especially so as genomic studies expand beyond model system organisms to encompass the full diversity of eukaryotes. Here we review some of the more commonly used programs for prediction of proteins that function in mitochondria, or mitochondrion-related organelles in diverse eukaryotic lineages and provide recommendations on how to apply these methods. Furthermore, we compare the predictive performance of these programs on a mixed set of mitochondrial and non-mitochondrial proteins. Although N-terminal targeting peptide prediction programs tend to have the highest accuracy, they cannot be effectively used for partial coding sequences derived from high-throughput expressed sequence tag surveys where data for the N-terminus of the encoded protein is often missing. Therefore methods that do not rely on the presence of an N-terminal targeting sequence alone are extremely useful, especially for expressed sequence tag data. The best strategy for classification of unknown proteins is to use multiple programs, incorporating a variety of prediction strategies, and closely examine the predictions with an understanding of how each of those programs will likely handle the data.
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Affiliation(s)
- Daniel Gaston
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
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23
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Brinkmann H, Philippe H. The Diversity Of Eukaryotes And The Root Of The Eukaryotic Tree. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 607:20-37. [DOI: 10.1007/978-0-387-74021-8_2] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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24
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Jékely G. Origin of the nucleus and Ran-dependent transport to safeguard ribosome biogenesis in a chimeric cell. Biol Direct 2008; 3:31. [PMID: 18652645 PMCID: PMC2503971 DOI: 10.1186/1745-6150-3-31] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 07/24/2008] [Indexed: 11/18/2022] Open
Abstract
Background The origin of the nucleus is a central problem about the origin of eukaryotes. The common ancestry of nuclear pore complexes (NPC) and vesicle coating complexes indicates that the nucleus evolved via the modification of a pre-existing endomembrane system. Such an autogenous scenario is cell biologically feasible, but it is not clear what were the selective or neutral mechanisms that had led to the origin of the nuclear compartment. Results A key selective force during the autogenous origin of the nucleus could have been the need to segregate ribosome factories from the cytoplasm where ribosomal proteins (RPs) of the protomitochondrium were synthesized. After its uptake by an anuclear cell the protomitochondrium transferred several of its RP genes to the host genome. Alphaproteobacterial RPs and archaebacterial-type host ribosomes were consequently synthesized in the same cytoplasm. This could have led to the formation of chimeric ribosomes. I propose that the nucleus evolved when the host cell compartmentalised its ribosome factories and the tightly linked genome to reduce ribosome chimerism. This was achieved in successive stages by first evolving karyopherin and RanGTP dependent chaperoning of RPs, followed by the evolution of a membrane network to serve as a diffusion barrier, and finally a hydrogel sieve to ensure selective permeability at nuclear pores. Computer simulations show that a gradual segregation of cytoplasm and nucleoplasm via these steps can progressively reduce ribosome chimerism. Conclusion Ribosome chimerism can provide a direct link between the selective forces for and the mechanisms of evolving nuclear transport and compartmentalisation. The detailed molecular scenario presented here provides a solution to the gradual evolution of nuclear compartmentalization from an anuclear stage. Reviewers This article was reviewed by Eugene V Koonin, Martijn Huynen, Anthony M. Poole and Patrick Forterre.
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Affiliation(s)
- Gáspár Jékely
- Max Planck Institute for Developmental Biology, Spemannstrasse 35. 72076 Tübingen, Germany.
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Hampl V, Silberman JD, Stechmann A, Diaz-Triviño S, Johnson PJ, Roger AJ. Genetic evidence for a mitochondriate ancestry in the 'amitochondriate' flagellate Trimastix pyriformis. PLoS One 2008; 3:e1383. [PMID: 18167542 PMCID: PMC2148110 DOI: 10.1371/journal.pone.0001383] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Accepted: 12/07/2007] [Indexed: 11/24/2022] Open
Abstract
Most modern eukaryotes diverged from a common ancestor that contained the α-proteobacterial endosymbiont that gave rise to mitochondria. The ‘amitochondriate’ anaerobic protist parasites that have been studied to date, such as Giardia and Trichomonas harbor mitochondrion-related organelles, such as mitosomes or hydrogenosomes. Yet there is one remaining group of mitochondrion-lacking flagellates known as the Preaxostyla that could represent a primitive ‘pre-mitochondrial’ lineage of eukaryotes. To test this hypothesis, we conducted an expressed sequence tag (EST) survey on the preaxostylid flagellate Trimastix pyriformis, a poorly-studied free-living anaerobe. Among the ESTs we detected 19 proteins that, in other eukaryotes, typically function in mitochondria, hydrogenosomes or mitosomes, 12 of which are found exclusively within these organelles. Interestingly, one of the proteins, aconitase, functions in the tricarboxylic acid cycle typical of aerobic mitochondria, whereas others, such as pyruvate:ferredoxin oxidoreductase and [FeFe] hydrogenase, are characteristic of anaerobic hydrogenosomes. Since Trimastix retains genetic evidence of a mitochondriate ancestry, we can now say definitively that all known living eukaryote lineages descend from a common ancestor that had mitochondria.
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Affiliation(s)
- Vladimir Hampl
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jeffrey D. Silberman
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Alexandra Stechmann
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sara Diaz-Triviño
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Patricia J. Johnson
- Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Andrew J. Roger
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- * To whom correspondence should be addressed. E-mail:
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De Jesus JB, Cuervo P, Junqueira M, Britto C, Silva-Filho FC, Sabóia-Vahia L, González LJ, Barbosa Domont G. Application of two-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for proteomic analysis of the sexually transmitted parasite Trichomonas vaginalis. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:1463-1473. [PMID: 17960578 DOI: 10.1002/jms.1286] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Trichomonas vaginalis is a sexually transmitted protozoan parasite that infects the human urogenital tract causing trichomoniasis, a worldwide disease. In this work, a fresh clinical isolate of T. vaginalis was used for study of the protein expression in this species. Two-dimensional gel electrophoresis (2-DE) and MALDI-TOF/TOF mass spectrometry (MS) were employed to create a reference map of soluble proteins in the pH range 4-7. A set of 116 proteins belonging to functional classes expressed in high and low abundance was identified by peptide mass fingerprinting and tandem MS. These identifications corresponded to 67 different proteins, suggesting that post-translational modifications are common phenomena in T. vaginalis. Identified proteins were classified into 16 groups according to biological processes. Among detected proteins we identified the major enzymes involved in both cytosolic and hydrogenosomal metabolic pathways, as well as putative protein targets for new drug design. In addition, this analysis allows validation of previous gene predictions confirming the expression of 15 hypothetical proteins. Finally, the findings here reported represent the first reference proteome map of T. vaginalis and the first steps towards the description of a comprehensive proteome map of this parasite.
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Affiliation(s)
- Jose Batista De Jesus
- Laboratório de Biologia Molecular e Doenças Endêmicas, Departamento de Bioquímica e Biologia Molecular, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
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27
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De Jesus JB, Cuervo P, Junqueira M, Britto C, Silva-Filho FCE, Soares MJ, Cupolillo E, Fernandes O, Domont GB. A further proteomic study on the effect of iron in the human pathogen Trichomonas vaginalis. Proteomics 2007; 7:1961-72. [PMID: 17514679 DOI: 10.1002/pmic.200600797] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Iron is an essential element to support the growth and survival of Trichomonas vaginalis. It plays a critical role in the host-parasite interaction, and modulates the expression of virulence factors in this protozoan. In this work, parasites grown in iron-rich and iron-depleted media were analyzed by (i) light and scanning electron microscopy and (ii) 2-DE and MS. Withdrawal of iron from the culture medium resulted in dramatic changes in both the morphology and in the proteome pattern of T. vaginalis. Trophozoites underwent transformation from ellipsoid or amoeboid forms to rounded cells, whose flagella and axostyle were internalized. Forty-five proteins differentially expressed in parasites cultivated in the absence of iron were identified. In iron-depleted parasites, enzymes involved in energetic metabolism, proteolysis and hydrogenosomal iron-sulfur (Fe-S) proteins were down-regulated or even suppressed. Among up-regulated proteins, six isoforms of actin were detected. In addition, phosphoenolpyruvate carboxykinase, putative lactate dehydrogenase, and putative adenosine triphosphatase were also up-regulated or were exclusively observed in gels related to iron-depleted parasites. Our data demonstrate that iron has a pivotal role in the regulation of the morphological transformation of T. vaginalis and modulates the expression of both Fe-S and non-Fe-S proteins in the parasite.
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Affiliation(s)
- Jose Batista De Jesus
- Departamento de Bioquímica e Biologia Molecular, Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, RJ, Brasil.
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28
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Waters ER, Rioflorido I. Evolutionary analysis of the small heat shock proteins in five complete algal genomes. J Mol Evol 2007; 65:162-74. [PMID: 17684698 DOI: 10.1007/s00239-006-0223-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Accepted: 04/04/2007] [Indexed: 11/29/2022]
Abstract
Small heat shock proteins (sHSPs) are chaperones that are crucial in the heat shock response but also have important nonstress roles within the cell. sHSPs are found in all three domains of life (Bacteria, Archaea, and Eukarya). These proteins are particularly diverse within land plants and the evolutionary origin of the land plant sHSP families is still an open question. Here we describe the identification of 17 small sHSPs from the complete genome sequences of five diverse algae: Chlamydomonas reinhardtii, Cyanidioschyzon merolae, Ostreococcus lucimarinus, Ostreococcus tauri, and Thalassiosira pseudonana. Our analysis indicates that the number and diversity of algal sHSPs are not correlated with adaptation to extreme conditions. While all of the algal sHSPs identified are members of this large and important superfamily, none of these sHSPs are members of the diverse land plant sHSP families. The evolutionary relationships among the algal sHSPs and homologues from bacteria and other eukaryotes are consistent with the hypothesis that the land plant chloroplast and mitochondrion sHSPs did not originate from the endosymbionts of the chloroplast and mitochondria. In addition the evolutionary history of the sHSPs is very different from that of the HSP70s. Finally, our analysis of the algal sHSPs sequences in light of the known sHSP crystal structures and functional data suggests that the sHSPs possess considerable structural and functional diversity.
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Affiliation(s)
- Elizabeth R Waters
- Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-4614, USA.
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29
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Sokolova YY, Snigirevskaya ES, Komissarchik YY. The Golgi apparatus in parasitic protists. ACTA ACUST UNITED AC 2007. [DOI: 10.1134/s1990519x07040037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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30
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Hwang UW. Prokaryotic and eukaryotic features observed on the secondary structures of Giardia SSU rRNAs and its phylogenetic implications. Parasitol Res 2007; 100:1159-63. [PMID: 17279392 DOI: 10.1007/s00436-007-0471-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Accepted: 01/17/2007] [Indexed: 10/23/2022]
Abstract
Phylogenetic position of a diplomonad protist Giardia, a principle cause of diarrhea, among eukaryotes has been vigorously debated so far. Through the comparisons of primary and secondary structures of SSU rRNAs of G. intestinalis, G. microti, G. ardeae, and G. muris, I found two major indel regions (a 6-nt indel and a 22-26-nt indel), which correspond to the helix 10 of the V2 region and helices E23-8 to E23-9 of the V4 region, respectively. As generally shown in eukaryotes, G. intestinalis and G. microti have commonly a relatively longer helix 10 (a 7-bp stem and a 4-nt loop), and also the eukaryote-specific helices E23-6 to E23-9. On the other hand, G. muris and G. ardeae have a shorter helix 10: a 2-bp stem and a 6-nt loop in G. ardeae and a 3-bp stem and a 6-nt loop in G. muris. In the V4, they have a single long helix (like the P23-1 helix in prokaryotes) instead of the helices E23-6 to E23-9. Among the four Giardia species, co-appearance of prokaryote- and eukaryote-typical features might be significant evidence to suggest that Giardia (Archezoa) is a living fossil showing an "intermediate stage" during the evolution from prokaryotes to eukaryotes.
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Affiliation(s)
- Ui Wook Hwang
- Department of Biology, Teachers College, Kyungpook National University, Daegu 702-701, South Korea.
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31
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Jékely G. Origin of phagotrophic eukaryotes as social cheaters in microbial biofilms. Biol Direct 2007; 2:3. [PMID: 17239231 PMCID: PMC1794243 DOI: 10.1186/1745-6150-2-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 01/19/2007] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The origin of eukaryotic cells was one of the most dramatic evolutionary transitions in the history of life. It is generally assumed that eukaryotes evolved later then prokaryotes by the transformation or fusion of prokaryotic lineages. However, as yet there is no consensus regarding the nature of the prokaryotic group(s) ancestral to eukaryotes. Regardless of this, a hardly debatable fundamental novel characteristic of the last eukaryotic common ancestor was the ability to exploit prokaryotic biomass by the ingestion of entire cells, i.e. phagocytosis. The recent advances in our understanding of the social life of prokaryotes may help to explain the origin of this form of total exploitation. PRESENTATION OF THE HYPOTHESIS Here I propose that eukaryotic cells originated in a social environment, a differentiated microbial mat or biofilm that was maintained by the cooperative action of its members. Cooperation was costly (e.g. the production of developmental signals or an extracellular matrix) but yielded benefits that increased the overall fitness of the social group. I propose that eukaryotes originated as selfish cheaters that enjoyed the benefits of social aggregation but did not contribute to it themselves. The cheaters later evolved into predators that lysed other cells and eventually became professional phagotrophs. During several cycles of social aggregation and dispersal the number of cheaters was contained by a chicken game situation, i.e. reproductive success of cheaters was high when they were in low abundance but was reduced when they were over-represented. Radical changes in cell structure, including the loss of the rigid prokaryotic cell wall and the development of endomembranes, allowed the protoeukaryotes to avoid cheater control and to exploit nutrients more efficiently. Cellular changes were buffered by both the social benefits and the protective physico-chemical milieu of the interior of biofilms. Symbiosis with the mitochondial ancestor evolved after phagotrophy as alphaproteobacterial prey developed post-ingestion defence mechanisms to circumvent digestion in the food vacuole. Mitochondrial symbiosis triggered the origin of the nucleus. Cilia evolved last and allowed eukaryotes to predate also on planktonic prey. I will discuss how this scenario may possibly fit into the contrasting phylogenetic frameworks that have been proposed. TESTING THE HYPOTHESIS Some aspects of the hypothesis can be tested experimentally by studying the level of exploitation cheaters can reach in social microbes. It would be interesting to test whether absorption of nutrients from lysed fellow colony members can happen and if cheaters can evolve into predators that actively digest neighbouring cells. IMPLICATIONS OF THE HYPOTHESIS The hypothesis highlights the importance of social exploitation in cell evolution and how a social environment can buffer drastic cellular transformations that would be lethal for planktonic forms.
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Affiliation(s)
- Gáspár Jékely
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
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33
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de Andrade Rosa I, Einicker-Lamas M, Roney Bernardo R, Previatto LM, Mohana-Borges R, Morgado-Díaz JA, Benchimol M. Cardiolipin in hydrogenosomes: evidence of symbiotic origin. EUKARYOTIC CELL 2006; 5:784-7. [PMID: 16607026 PMCID: PMC1459669 DOI: 10.1128/ec.5.4.784-787.2006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hydrogenosomes are found in organisms that lack typical mitochondria. Cardiolipin is a phospholipid located exclusively in bacterial membranes and the inner membrane of mitochondria. Here we show, by cell fractionation, thin-layer chromatography, high-pressure liquid chromatography, and matrix-assisted laser desorption ionization-time of flight mass spectrometry that hydrogenosomes of Tritrichomonas foetus, a cattle vaginal parasite, contain cardiolipin, which is strong evidence for its endosymbiotic origin.
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Affiliation(s)
- Ivone de Andrade Rosa
- Laboratorio de Ultraestrutura Celular, Univeridade Santa Ursula, Rio de Janeiro, Brazil
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34
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Embley TM. Multiple secondary origins of the anaerobic lifestyle in eukaryotes. Philos Trans R Soc Lond B Biol Sci 2006; 361:1055-67. [PMID: 16754614 PMCID: PMC1578728 DOI: 10.1098/rstb.2006.1844] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Classical ideas for early eukaryotic evolution often posited a period of anaerobic evolution producing a nucleated phagocytic cell to engulf the mitochondrial endosymbiont, whose presence allowed the host to colonize emerging aerobic environments. This idea was given credence by the existence of contemporary anaerobic eukaryotes that were thought to primitively lack mitochondria, thus providing examples of the type of host cell needed. However, the groups key to this hypothesis have now been shown to contain previously overlooked mitochondrial homologues called hydrogenosomes or mitosomes; organelles that share common ancestry with mitochondria but which do not carry out aerobic respiration. Mapping these data on the unfolding eukaryotic tree reveals that secondary adaptation to anaerobic habitats is a reoccurring theme among eukaryotes. The apparent ubiquity of mitochondrial homologues bears testament to the importance of the mitochondrial endosymbiosis, perhaps as a founding event, in eukaryotic evolution. Comparative study of different mitochondrial homologues is needed to determine their fundamental importance for contemporary eukaryotic cells.
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Affiliation(s)
- T Martin Embley
- The Devonshire Building, University of Newcastle upon Tyne, Division of Biology, NE1 7RU, UK.
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35
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Hackstein JHP, Tjaden J, Huynen M. Mitochondria, hydrogenosomes and mitosomes: products of evolutionary tinkering! Curr Genet 2006; 50:225-45. [PMID: 16897087 DOI: 10.1007/s00294-006-0088-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 06/29/2006] [Accepted: 07/02/2006] [Indexed: 11/29/2022]
Affiliation(s)
- Johannes H P Hackstein
- Department of Evolutionary Microbiology, Faculty of Science, Radboud University Nijmegen, Toernooiveld 1, 6525, ED Nijmegen, The Netherlands.
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Abstract
Large-scale comparative genomics in harness with proteomics has substantiated fundamental features of eukaryote cellular evolution. The evolutionary trajectory of modern eukaryotes is distinct from that of prokaryotes. Data from many sources give no direct evidence that eukaryotes evolved by genome fusion between archaea and bacteria. Comparative genomics shows that, under certain ecological settings, sequence loss and cellular simplification are common modes of evolution. Subcellular architecture of eukaryote cells is in part a physical-chemical consequence of molecular crowding; subcellular compartmentation with specialized proteomes is required for the efficient functioning of proteins.
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Affiliation(s)
- C G Kurland
- Department of Microbial Ecology, Lund University, Lund, Sweden
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van der Giezen M, León-Avila G, Tovar J. Characterization of chaperonin 10 (Cpn10) from the intestinal human pathogen Entamoeba histolytica. MICROBIOLOGY-SGM 2005; 151:3107-3115. [PMID: 16151221 DOI: 10.1099/mic.0.28068-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Entamoeba histolytica is the causative agent of amoebiasis, a poverty-related disease that kills an estimated 100 000 people each year. E. histolytica does not contain "standard mitochondria", but harbours mitochondrial remnant organelles called mitosomes. These organelles are characterized by the presence of mitochondrial chaperonin Cpn60, but little else is known about the functions and molecular composition of mitosomes. In this study, a gene encoding molecular chaperonin Cpn10--the functional partner of Cpn60--was cloned, and its structure and expression were characterized, as well as the cellular localization of its encoded protein. The 5' untranslated region of the gene contains all of the structural promoter elements required for transcription in this organism. The amoebic Cpn10, like Cpn60, is not significantly upregulated upon heat-shock treatment. Computer-assisted protein modelling, and specific antibodies against Cpn10 and Cpn60, suggest that both proteins interact with each other, and that they function in the same intracellular compartment. Thus, E. histolytica appears to have retained at least two of the key molecular components required for the refolding of imported mitosomal proteins.
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Affiliation(s)
- Mark van der Giezen
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
| | - Gloria León-Avila
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
| | - Jorge Tovar
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
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Fischer WM, Palmer JD. Evidence from small-subunit ribosomal RNA sequences for a fungal origin of Microsporidia. Mol Phylogenet Evol 2005; 36:606-22. [PMID: 15923129 DOI: 10.1016/j.ympev.2005.03.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2004] [Revised: 03/24/2005] [Accepted: 03/27/2005] [Indexed: 10/25/2022]
Abstract
The phylum Microsporidia comprises a species-rich group of minute, single-celled, and intra-cellular parasites. Lacking normal mitochondria and with unique cytology, microsporidians have sometimes been thought to be a lineage of ancient eukaryotes. Although phylogenetic analyses using small-subunit ribosomal RNA (SSU-rRNA) genes almost invariably place the Microsporidia among the earliest branches on the eukaryotic tree, many other molecules suggest instead a relationship with fungi. Using maximum likelihood methods and a diverse SSU-rRNA data set, we have re-evaluated the phylogenetic affiliations of Microsporidia. We demonstrate that tree topologies used to estimate likelihood model parameters can materially affect phylogenetic searches. We present a procedure for reducing this bias: "tree-based site partitioning," in which a comprehensive set of alternative topologies is used to estimate sequence data partitions based on inferred evolutionary rates. This hypothesis-driven approach appears to be capable of utilizing phylogenetic information that is not available to standard likelihood implementations (e.g., approximation to a gamma distribution); we have employed it in maximum likelihood and Bayesian analysis. Applying our method to a phylogenetically diverse SSU-rRNA data set revealed that the early diverging ("deep") placement of Microsporidia typically found in SSU-rRNA trees is no better than a fungal placement, and that the likeliest placement of Microsporidia among non-long-branch eukaryotic taxa is actually within fungi. These results illustrate the importance of hypothesis testing in parameter estimation, provide a way to address certain problems in difficult data sets, and support a fungal origin for the Microsporidia.
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Affiliation(s)
- William M Fischer
- Biology Department, Indiana University, Jordan Hall 142, Bloomington, IN 47405-3700, USA.
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Hampl V, Horner DS, Dyal P, Kulda J, Flegr J, Foster PG, Embley TM. Inference of the Phylogenetic Position of Oxymonads Based on Nine Genes: Support for Metamonada and Excavata. Mol Biol Evol 2005; 22:2508-18. [PMID: 16120804 DOI: 10.1093/molbev/msi245] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Circumscribing major eukaryote groups and resolving higher order relationships between them are among the most challenging tasks facing molecular evolutionists. Recently, evidence suggesting a new supergroup (the Excavata) comprising a wide array of flagellates has been collected. This group consists of diplomonads, retortamonads, Carpediemonas, heteroloboseans, Trimastix, jakobids, and Malawimonas, all of which possess a particular type of ventral feeding groove that is proposed to be homologous. Euglenozoans, parabasalids, and oxymonads have also been associated with Excavata as their relationships to one or more core excavate taxa were demonstrated. However, the main barrier to the general acceptance of Excavata is that its existence is founded primarily on cytoskeletal similarities, without consistent support from molecular phylogenetics. In gene trees, Excavata are typically not recovered together. In this paper, we present an analysis of the phylogenetic position of oxymonads (genus Monocercomonoides) based on concatenation of eight protein sequences (alpha-tubulin, beta-tubulin, gamma-tubulin, EF-1alpha, EF-2, cytosolic (cyt) HSP70, HSP90, and ubiquitin) and 18S rRNA. We demonstrate that the genes are in conflict regarding the position of oxymonads. Concatenation of alpha- and beta-tubulin placed oxymonads in the plant-chromist part of the tree, while the concatenation of other genes recovered a well-supported group of Metamonada (oxymonads, diplomonads, and parabasalids) that branched weakly with euglenozoans--connecting all four excavates included in the analyses and thus providing conditional support for the existence of Excavata.
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Affiliation(s)
- Vladimír Hampl
- Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
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Thomarat F, Vivarès CP, Gouy M. Phylogenetic analysis of the complete genome sequence of Encephalitozoon cuniculi supports the fungal origin of microsporidia and reveals a high frequency of fast-evolving genes. J Mol Evol 2005; 59:780-91. [PMID: 15599510 DOI: 10.1007/s00239-004-2673-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2003] [Accepted: 06/29/2004] [Indexed: 10/26/2022]
Abstract
Microsporidia are unicellular eukaryotes living as obligate intracellular parasites. Lacking mitochondria, they were initially considered as having diverged before the endosymbiosis at the origin of mitochondria. That microsporidia were primitively amitochondriate was first questioned by the discovery of microsporidial sequences homologous to genes encoding mitochondrial proteins and then refuted by the identification of remnants of mitochondria in their cytoplasm. Various molecular phylogenies also cast doubt on the early divergence of microsporidia, these organisms forming a monophyletic group with or within the fungi. The 2001 proteins putatively encoded by the complete genome of Encephalitozoon cuniculi provided powerful data to test this hypothesis. Phylogenetic analysis of 99 proteins selected as adequate phylogenetic markers indicated that the E. cuniculi sequences having the lowest evolutionary rates preferentially clustered with fungal sequences or, more rarely, with both animal and fungal sequences. Because sequences with low evolutionary rates are less sensitive to the long-branch attraction artifact, we concluded that microsporidia are evolutionarily related to fungi. This analysis also allowed comparing the accuracy of several phylogenetic algorithms for a fast-evolving lineage with real rather than simulated sequences.
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Affiliation(s)
- Fabienne Thomarat
- Laboratoire de Biométrie et Biologie Evolutive, UMR CNRS 5558, Université Claude Bernard Lyon I, 43 boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
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Gabaldón T, Huynen MA. Shaping the mitochondrial proteome. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1659:212-20. [PMID: 15576054 DOI: 10.1016/j.bbabio.2004.07.011] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 07/15/2004] [Accepted: 07/28/2004] [Indexed: 10/26/2022]
Abstract
Mitochondria are eukaryotic organelles that originated from a single bacterial endosymbiosis some 2 billion years ago. The transition from the ancestral endosymbiont to the modern mitochondrion has been accompanied by major changes in its protein content, the so-called proteome. These changes included complete loss of some bacterial pathways, amelioration of others and gain of completely new complexes of eukaryotic origin such as the ATP/ADP translocase and most of the mitochondrial protein import machinery. This renewal of proteins has been so extensive that only 14-16% of modern mitochondrial proteome has an origin that can be traced back to the bacterial endosymbiont. The rest consists of proteins of diverse origin that were eventually recruited to function in the organelle. This shaping of the proteome content reflects the transformation of mitochondria into a highly specialized organelle that, besides ATP production, comprises a variety of functions within the eukaryotic metabolism. Here we review recent advances in the fields of comparative genomics and proteomics that are throwing light on the origin and evolution of the mitochondrial proteome.
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Affiliation(s)
- Toni Gabaldón
- NCMLS, Nijmegen Center for Molecular Life Sciences, P/O: CMBI, Center for Molecular and Biomolecular Informatics, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
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van der Giezen M, Tovar J, Clark CG. Mitochondrion‐Derived Organelles in Protists and Fungi. INTERNATIONAL REVIEW OF CYTOLOGY 2005; 244:175-225. [PMID: 16157181 DOI: 10.1016/s0074-7696(05)44005-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The mitochondrion is generally considered to be a defining feature of eukaryotic cells, yet most anaerobic eukaryotes lack this organelle. Many of these were previously thought to derive from eukaryotes that diverged prior to acquisition of the organelle through endosymbiosis. It is now known that all extant eukaryotes are descended from an ancestor that had a mitochondrion and that in anaerobic eukaryotes the organelle has been modified into either hydrogenosomes, which continue to generate energy for the host cell, or mitosomes, which do not. These organelles have each arisen independently several times. Recent evidence suggests a shared derived characteristic that may be responsible for the retention of the organelles in the absence of the better-known mitochondrial functions--iron-sulfur cluster assembly. This review explores the events leading to this new understanding of mitochondrion-derived organelles in amitochondriate eukaryotes, the current state of our knowledge, and future areas for investigation.
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Affiliation(s)
- Mark van der Giezen
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom
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44
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Hackstein JHP, Yarlett N. Hydrogenosomes and symbiosis. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2005; 41:117-42. [PMID: 16623392 DOI: 10.1007/3-540-28221-1_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Johannes H P Hackstein
- Department of Evolutionary Microbiology, Faculty of Science, Radboud University Nijmegen, Toernooiveld 1, NL 6525 ED Nijmegen, The Netherlands.
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Slapeta J, Keithly JS. Cryptosporidium parvum mitochondrial-type HSP70 targets homologous and heterologous mitochondria. EUKARYOTIC CELL 2004; 3:483-94. [PMID: 15075277 PMCID: PMC387664 DOI: 10.1128/ec.3.2.483-494.2004] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A mitochondrial HSP70 gene (Cp-mtHSP70) is described for the apicomplexan Cryptosporidium parvum, an agent of diarrhea in humans and animals. Mitochondrial HSP70 is known to have been acquired from the proto-mitochondrial endosymbiont. The amino acid sequence of Cp-mtHSP70 shares common domains with mitochondrial and proteobacterial homologues, including 34 amino acids of an NH2-terminal mitochondrion-like targeting presequence. Phylogenetic reconstruction places Cp-mtHSP70 within the mitochondrial clade of HSP70 homologues. Using reverse transcription-PCR, Cp-mtHSP70 mRNA was observed in C. parvum intracellular stages cultured in HCT-8 cells. Polyclonal antibodies to Cp-mtHSP70 recognize a approximately 70-kDa protein in Western blot analysis of sporozoite extracts. Both fluorescein- and immunogold-labeled anti-Cp-mtHSP70 localize to a single mitochondrial compartment in close apposition to the nucleus. Furthermore, the NH2-terminal presequence of Cp-mtHSP70 can correctly target green fluorescent protein to the single mitochondrion of the apicomplexan Toxoplasma gondii and the mitochondrial network of the yeast Saccharomyces cerevisiae. When this presequence was truncated, the predicted amphiphilic alpha-helix was shown to be essential for import into the yeast mitochondrion. These data further support the presence of a secondarily reduced relict mitochondrion in C. parvum.
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Affiliation(s)
- Jan Slapeta
- Wadsworth Center, New York State Department of Health, Albany, New York 12201-2002, USA.
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Rivière L, van Weelden SWH, Glass P, Vegh P, Coustou V, Biran M, van Hellemond JJ, Bringaud F, Tielens AGM, Boshart M. Acetyl:succinate CoA-transferase in procyclic Trypanosoma brucei. Gene identification and role in carbohydrate metabolism. J Biol Chem 2004; 279:45337-46. [PMID: 15326192 DOI: 10.1074/jbc.m407513200] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acetyl:succinate CoA-transferase (ASCT) is an acetate-producing enzyme shared by hydrogenosomes, mitochondria of trypanosomatids, and anaerobically functioning mitochondria. The gene encoding ASCT in the protozoan parasite Trypanosoma brucei was identified as a new member of the CoA transferase family. Its assignment to ASCT activity was confirmed by 1) a quantitative correlation of protein expression and activity upon RNA interference-mediated repression, 2) the absence of activity in homozygous Deltaasct/Deltaasct knock out cells, 3) mitochondrial colocalization of protein and activity, 4) increased activity and acetate excretion upon transgenic overexpression, and 5) depletion of ASCT activity from lysates upon immunoprecipitation. Genetic ablation of ASCT produced a severe growth phenotype, increased glucose consumption, and excretion of beta-hydroxybutyrate and pyruvate, indicating accumulation of acetyl-CoA. Analysis of the excreted end products of (13)C-enriched and (14)C-labeled glucose metabolism showed that acetate excretion was only slightly reduced. Adaptation to ASCT deficiency, however, was an infrequent event at the population level, indicating the importance of this enzyme. These studies show that ASCT is indeed involved in acetate production, but is not essential, as apparently it is not the only enzyme that produces acetate in T. brucei.
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Affiliation(s)
- Loïc Rivière
- Laboratoire de Genomique Fonctionnelle des Trypanosomatides, UMR-5162 CNRS, Université Victor Segalen Bordeaux II, 33076 Bordeaux Cedex, France
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Soyer-Gobillard MO, Schrevel J. André Lwoff (1902–1994), Nobel Prize of Medicine, as Protistologist. Protist 2003; 154:455-68. [PMID: 14658501 DOI: 10.1078/143446103322454185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Marie-Odile Soyer-Gobillard
- Observatoire Océanologique de Banyuls, Laboratoire Arago, University Paris 6, UMR CNRS 7628 "Modèles en Biologie Cellulaire et Evolutive", F-66651 Banyuls-sur-Mer, France.
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49
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Dyall SD, Lester DC, Schneider RE, Delgadillo-Correa MG, Plümper E, Martinez A, Koehler CM, Johnson PJ. Trichomonas vaginalis Hmp35, a putative pore-forming hydrogenosomal membrane protein, can form a complex in yeast mitochondria. J Biol Chem 2003; 278:30548-61. [PMID: 12766161 DOI: 10.1074/jbc.m304032200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An abundant integral membrane protein, Hmp35, has been isolated from hydrogenosomes of Trichomonas vaginalis. This protein has no known homologue and exists as a stable 300-kDa complex, termed HMP35, in membranes of the hydrogenosome. By using blue native gel electrophoresis, we found the HMP35 complex to be stable in 2 m NaCl and up to 5 m urea. The endogenous Hmp35 protein was largely protease-resistant. The protein has a predominantly beta-sheet structure and predicted transmembrane domains that may form a pore. Interestingly, the protein has a high number of cysteine residues, some of which are arranged in motifs that resemble the RING finger, suggesting that they could be coordinating zinc or another divalent cation. Our data show that Hmp35 forms one intramolecular but no intermolecular disulfide bonds. We have isolated the HMP35 complex by expressing a His-tagged Hmp35 protein in vivo followed by purification with nickel-agarose beads. The purified 300-kDa complex consists of mostly Hmp35 with lesser amounts of 12-, 25-27-, and 32-kDa proteins. The stoichiometry of proteins in the complex indicates that Hmp35 exists as an oligomer. Hmp35 can be targeted heterologously into yeast mitochondria, despite the lack of homology with any yeast protein, demonstrating the compatibility of mitochondrial and hydrogenosomal protein translocation machineries.
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Affiliation(s)
- Sabrina D Dyall
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, California 90095-1489 and the Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095-1569
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Mariante RM, Guimarães CA, Linden R, Benchimol M. Hydrogen peroxide induces caspase activation and programmed cell death in the amitochondrial Tritrichomonas foetus. Histochem Cell Biol 2003; 120:129-41. [PMID: 12844218 DOI: 10.1007/s00418-003-0548-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2003] [Indexed: 10/26/2022]
Abstract
Tritrichomonas foetus is an amitochondrial parasite protist which lacks typical eukaryote organelles such as mitochondria and peroxisomes, but possesses the hydrogenosome, a double-membrane-bound organelle that produces ATP. The cell death of amitochondrial organisms is poorly studied. In the present work, the cytotoxic effects of hydrogen peroxide on T. foetus and its participation on cell death were analyzed. We took advantage of several microscopy techniques, including videomicroscopy, light microscopy immunocytochemistry for detection of caspase activation, and scanning and transmission electron microscopy. We report here that in T. foetus: (1) H(2)O(2) leads to loss of motility and induces cell death, (2) the dying cells exhibit some characteristics similar to those found during the death of other organisms, and (3) a caspase-like protein seems to be activated during the death process. Thus, we propose that, although T. foetus does not present mitochondria nor any known pathways of cell death, it is likely that it bears mechanisms of cell demise. T. foetus exhibits morphological and physiological alterations in response to H(2)O(2) treatment. The hydrogenosome, a unique organelle which is supposed to share a common ancestral origin with mitochondria and has an important role in oxidative responses in trichomonads, is a candidate for participating in this event.
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Affiliation(s)
- Rafael M Mariante
- Programa de Ciências Morfológicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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