1
|
Harada R, Hirakawa Y, Yabuki A, Kim E, Yazaki E, Kamikawa R, Nakano K, Eliáš M, Inagaki Y. Encyclopedia of Family A DNA Polymerases Localized in Organelles: Evolutionary Contribution of Bacteria Including the Proto-Mitochondrion. Mol Biol Evol 2024; 41:msae014. [PMID: 38271287 PMCID: PMC10877234 DOI: 10.1093/molbev/msae014] [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: 08/29/2023] [Revised: 01/12/2024] [Accepted: 01/19/2024] [Indexed: 01/27/2024] Open
Abstract
DNA polymerases synthesize DNA from deoxyribonucleotides in a semiconservative manner and serve as the core of DNA replication and repair machinery. In eukaryotic cells, there are 2 genome-containing organelles, mitochondria, and plastids, which were derived from an alphaproteobacterium and a cyanobacterium, respectively. Except for rare cases of genome-lacking mitochondria and plastids, both organelles must be served by nucleus-encoded DNA polymerases that localize and work in them to maintain their genomes. The evolution of organellar DNA polymerases has yet to be fully understood because of 2 unsettled issues. First, the diversity of organellar DNA polymerases has not been elucidated in the full spectrum of eukaryotes. Second, it is unclear when the DNA polymerases that were used originally in the endosymbiotic bacteria giving rise to mitochondria and plastids were discarded, as the organellar DNA polymerases known to date show no phylogenetic affinity to those of the extant alphaproteobacteria or cyanobacteria. In this study, we identified from diverse eukaryotes 134 family A DNA polymerase sequences, which were classified into 10 novel types, and explored their evolutionary origins. The subcellular localizations of selected DNA polymerases were further examined experimentally. The results presented here suggest that the diversity of organellar DNA polymerases has been shaped by multiple transfers of the PolI gene from phylogenetically broad bacteria, and their occurrence in eukaryotes was additionally impacted by secondary plastid endosymbioses. Finally, we propose that the last eukaryotic common ancestor may have possessed 2 mitochondrial DNA polymerases, POP, and a candidate of the direct descendant of the proto-mitochondrial DNA polymerase I, rdxPolA, identified in this study.
Collapse
Affiliation(s)
- Ryo Harada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Yoshihisa Hirakawa
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Akinori Yabuki
- Deep-Sea Biodiversity Research Group, Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Eunsoo Kim
- Division of EcoScience, Ewha Womans University, Seoul, South Korea
- Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA
| | - Euki Yazaki
- Research Center for Advanced Analysis, National Agriculture and Food Research Organization, Tsukuba, Japan
- Interdisciplinary Theoretical and Mathematical Sciences program (iTHEMS), RIKEN, Wako, Saitama, Japan
| | - Ryoma Kamikawa
- Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Kentaro Nakano
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Marek Eliáš
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Yuji Inagaki
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Japan
| |
Collapse
|
2
|
Vasilev J, Mix AK, Heimerl T, Maier UG, Moog D. Inferred Subcellular Localization of Peroxisomal Matrix Proteins of Guillardia theta Suggests an Important Role of Peroxisomes in Cryptophytes. FRONTIERS IN PLANT SCIENCE 2022; 13:889662. [PMID: 35783940 PMCID: PMC9244630 DOI: 10.3389/fpls.2022.889662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
Peroxisomes participate in several important metabolic processes in eukaryotic cells, such as the detoxification of reactive oxygen species (ROS) or the degradation of fatty acids by β-oxidation. Recently, the presence of peroxisomes in the cryptophyte Guillardia theta and other "chromalveolates" was revealed by identifying proteins for peroxisomal biogenesis. Here, we investigated the subcellular localization of candidate proteins of G. theta in the diatom Phaeodactylum tricornutum, either possessing a putative peroxisomal targeting signal type 1 (PTS1) sequence or factors lacking a peroxisomal targeting signal but known to be involved in β-oxidation. Our results indicate important contributions of the peroxisomes of G. theta to the carbohydrate, ether phospholipid, nucleotide, vitamin K, ROS, amino acid, and amine metabolisms. Moreover, our results suggest that in contrast to many other organisms, the peroxisomes of G. theta are not involved in the β-oxidation of fatty acids, which exclusively seems to occur in the cryptophyte's mitochondria.
Collapse
Affiliation(s)
- Jana Vasilev
- Laboratory for Cell Biology, Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Ann-Kathrin Mix
- Laboratory for Cell Biology, Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Thomas Heimerl
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Marburg, Germany
| | - Uwe G. Maier
- Laboratory for Cell Biology, Department of Biology, Philipps-University Marburg, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Marburg, Germany
| | - Daniel Moog
- Laboratory for Cell Biology, Department of Biology, Philipps-University Marburg, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Marburg, Germany
| |
Collapse
|
3
|
Kobakhidze G, Sethi A, Valimehr S, Ralph SA, Rouiller I. The AAA+ ATPase p97 as a novel parasite and tuberculosis drug target. Trends Parasitol 2022; 38:572-590. [DOI: 10.1016/j.pt.2022.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
|
4
|
Using Diatom and Apicomplexan Models to Study the Heme Pathway of Chromera velia. Int J Mol Sci 2021; 22:ijms22126495. [PMID: 34204357 PMCID: PMC8233740 DOI: 10.3390/ijms22126495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 12/20/2022] Open
Abstract
Heme biosynthesis is essential for almost all living organisms. Despite its conserved function, the pathway’s enzymes can be located in a remarkable diversity of cellular compartments in different organisms. This location does not always reflect their evolutionary origins, as might be expected from the history of their acquisition through endosymbiosis. Instead, the final subcellular localization of the enzyme reflects multiple factors, including evolutionary origin, demand for the product, availability of the substrate, and mechanism of pathway regulation. The biosynthesis of heme in the apicomonad Chromera velia follows a chimeric pathway combining heme elements from the ancient algal symbiont and the host. Computational analyses using different algorithms predict complex targeting patterns, placing enzymes in the mitochondrion, plastid, endoplasmic reticulum, or the cytoplasm. We employed heterologous reporter gene expression in the apicomplexan parasite Toxoplasma gondii and the diatom Phaeodactylum tricornutum to experimentally test these predictions. 5-aminolevulinate synthase was located in the mitochondria in both transfection systems. In T. gondii, the two 5-aminolevulinate dehydratases were located in the cytosol, uroporphyrinogen synthase in the mitochondrion, and the two ferrochelatases in the plastid. In P. tricornutum, all remaining enzymes, from ALA-dehydratase to ferrochelatase, were placed either in the endoplasmic reticulum or in the periplastidial space.
Collapse
|
5
|
Füssy Z, Faitová T, Oborník M. Subcellular Compartments Interplay for Carbon and Nitrogen Allocation in Chromera velia and Vitrella brassicaformis. Genome Biol Evol 2020; 11:1765-1779. [PMID: 31192348 PMCID: PMC6668581 DOI: 10.1093/gbe/evz123] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2019] [Indexed: 12/20/2022] Open
Abstract
Endosymbioses necessitate functional cooperation of cellular compartments to avoid pathway redundancy and streamline the control of biological processes. To gain insight into the metabolic compartmentation in chromerids, phototrophic relatives to apicomplexan parasites, we prepared a reference set of proteins probably localized to mitochondria, cytosol, and the plastid, taking advantage of available genomic and transcriptomic data. Training of prediction algorithms with the reference set now allows a genome-wide analysis of protein localization in Chromera velia and Vitrella brassicaformis. We confirm that the chromerid plastids house enzymatic pathways needed for their maintenance and photosynthetic activity, but for carbon and nitrogen allocation, metabolite exchange is necessary with the cytosol and mitochondria. This indeed suggests that the regulatory mechanisms operate in the cytosol to control carbon metabolism based on the availability of both light and nutrients. We discuss that this arrangement is largely shared with apicomplexans and dinoflagellates, possibly stemming from a common ancestral metabolic architecture, and supports the mixotrophy of the chromerid algae.
Collapse
Affiliation(s)
- Zoltán Füssy
- Faculty of Science, Department of Molecular Biology and Genetics, University of South Bohemia, České Budějovice, Czech Republic.,Department of Evolutionary Protistology, Institute of Parasitology, Biology Centre CAS, České Budějovice, Czech Republic
| | - Tereza Faitová
- Faculty of Science, Department of Molecular Biology and Genetics, University of South Bohemia, České Budějovice, Czech Republic.,Department of Evolutionary Protistology, Institute of Parasitology, Biology Centre CAS, České Budějovice, Czech Republic.,Faculty of Engineering and Natural Sciences, Department of Computer Science, Johannes Kepler University, Linz, Austria
| | - Miroslav Oborník
- Faculty of Science, Department of Molecular Biology and Genetics, University of South Bohemia, České Budějovice, Czech Republic.,Department of Evolutionary Protistology, Institute of Parasitology, Biology Centre CAS, České Budějovice, Czech Republic
| |
Collapse
|
6
|
Chen Z, Wang X, Li S, Yao J, Shao Z, Duan D. Verification of the Saccharina japonica Translocon Tic20 and its Localization in the Chloroplast Membrane in Diatoms. Int J Mol Sci 2019; 20:E4000. [PMID: 31426420 PMCID: PMC6720183 DOI: 10.3390/ijms20164000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/01/2019] [Accepted: 08/15/2019] [Indexed: 12/21/2022] Open
Abstract
Tic20 is an important translocon protein that plays a role in protein transport in the chloroplast. The sequence of Tic20 was determined in the lower brown alga Saccharina japonica. Structural analysis of SjTic20 revealed a noncanonical structure consisting of an N-terminal non-cyanobacterium-originated EF-hand domain (a helix-loop-helix structural domain) and a C-terminal cyanobacterium-originated Tic20 domain. Subcellular localization and transmembrane analysis indicated that SjTic20 featured an "M"-type Nin-Cin-terminal orientation, with four transmembrane domains in the innermost membrane of the chloroplast in the microalga Phaeodactylum tricornutum, and the EF-hand domain was entirely extruded into the chloroplast stroma. Our study provides information on the structure, localization, and topological features of SjTic20, and further functional analysis of SjTic20 in S. japonica is needed.
Collapse
Affiliation(s)
- Zhihang Chen
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
- University of Chinese Academy of Sciences, Beijing 100093, China
| | - Xiuliang Wang
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
| | - Shuang Li
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
- University of Chinese Academy of Sciences, Beijing 100093, China
| | - Jianting Yao
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Zhanru Shao
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Delin Duan
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
| |
Collapse
|
7
|
Wetherbee R, Jackson CJ, Repetti SI, Clementson LA, Costa JF, van de Meene A, Crawford S, Verbruggen H. The golden paradox - a new heterokont lineage with chloroplasts surrounded by two membranes. JOURNAL OF PHYCOLOGY 2019; 55:257-278. [PMID: 30536815 DOI: 10.1111/jpy.12822] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/23/2018] [Indexed: 06/09/2023]
Abstract
A marine, sand-dwelling, golden-brown alga is described from clonal cultures established from a high intertidal pool in southeastern Australia. This tiny, unicellular species, which we call the "golden paradox" (Chrysoparadoxa australica gen. et sp. nov.), is benthic, surrounded by a multilayered cell wall and attached to the substratum by a complex adhesive plug. Each vegetative cell gives rise to a single, naked zoospore with heterokont flagella that settles and may become briefly amoeboid prior to dividing. Daughter cells are initially amoeboid, then either permanently attach and return to the benthic stage or become motile again prior to final settlement. Two deeply lobed chloroplasts occupy opposite ends of the cell and are surrounded by only two membranes. The outer chloroplast membrane is continuous between the two chloroplasts via the outer membrane of the nuclear envelope. Only two membranes occupy the chloroplast-nucleus interface, the inner membrane of the nuclear envelope and the inner chloroplast membrane. A small pyrenoid is found in each chloroplast and closely abuts the nucleus or protrudes into it. It contains an unusual, membrane-bound inclusion that stains with SYBR green but is unlikely to be a nucleomorph. Phylogenies inferred from a 10-gene concatenated alignment show an early-branching position within the PX clade. The unusual morphological features and phylogenetic position indicate C. australica should be classified as a new class, Chrysoparadoxophyceae. Despite an atypical plastid, exploration of the C. australica transcriptome revealed typical heterokont protein targeting to the plastid.
Collapse
Affiliation(s)
- Richard Wetherbee
- School of BioSciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Christopher J Jackson
- School of BioSciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Sonja I Repetti
- School of BioSciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | | | - Joana F Costa
- School of BioSciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Allison van de Meene
- School of BioSciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Simon Crawford
- School of BioSciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Heroen Verbruggen
- School of BioSciences, University of Melbourne, Melbourne, Victoria, 3010, Australia
| |
Collapse
|
8
|
Mallo N, Fellows J, Johnson C, Sheiner L. Protein Import into the Endosymbiotic Organelles of Apicomplexan Parasites. Genes (Basel) 2018; 9:E412. [PMID: 30110980 PMCID: PMC6115763 DOI: 10.3390/genes9080412] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 07/31/2018] [Accepted: 08/07/2018] [Indexed: 01/26/2023] Open
Abstract
: The organelles of endosymbiotic origin, plastids, and mitochondria, evolved through the serial acquisition of endosymbionts by a host cell. These events were accompanied by gene transfer from the symbionts to the host, resulting in most of the organellar proteins being encoded in the cell nuclear genome and trafficked into the organelle via a series of translocation complexes. Much of what is known about organelle protein translocation mechanisms is based on studies performed in common model organisms; e.g., yeast and humans or Arabidopsis. However, studies performed in divergent organisms are gradually accumulating. These studies provide insights into universally conserved traits, while discovering traits that are specific to organisms or clades. Apicomplexan parasites feature two organelles of endosymbiotic origin: a secondary plastid named the apicoplast and a mitochondrion. In the context of the diseases caused by apicomplexan parasites, the essential roles and divergent features of both organelles make them prime targets for drug discovery. This potential and the amenability of the apicomplexan Toxoplasma gondii to genetic manipulation motivated research about the mechanisms controlling both organelles' biogenesis. Here we provide an overview of what is known about apicomplexan organelle protein import. We focus on work done mainly in T. gondii and provide a comparison to model organisms.
Collapse
Affiliation(s)
- Natalia Mallo
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, Glasgow G12 8QQ, UK.
| | - Justin Fellows
- Genetics and Biochemistry Branch, National Institute for Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Carla Johnson
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, Glasgow G12 8QQ, UK.
| | - Lilach Sheiner
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, Glasgow G12 8QQ, UK.
| |
Collapse
|
9
|
Grosche C, Diehl A, Rensing SA, Maier UG. Iron-Sulfur Cluster Biosynthesis in Algae with Complex Plastids. Genome Biol Evol 2018; 10:2061-2071. [PMID: 30085124 PMCID: PMC6105332 DOI: 10.1093/gbe/evy156] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2018] [Indexed: 12/15/2022] Open
Abstract
Plastids surrounded by four membranes harbor a special compartment between the outer and inner plastid membrane pair, the so-called periplastidal compartment (PPC). This cellular structure is usually presumed to be the reduced cytoplasm of a eukaryotic phototrophic endosymbiont, which was integrated into a host cell and streamlined into a plastid with a complex membrane structure. Up to date, no mitochondrion or mitochondrion-related organelle has been identified in the PPC of any representative. However, two prominent groups, the cryptophytes and the chlorarachniophytes, still harbor a reduced cell nucleus of symbiont origin, the nucleomorph, in their PPCs. Generally, many cytoplasmic and nucleus-located eukaryotic proteins need an iron–sulfur cofactor for their functionality. Beside some exceptions, their synthesis is depending on a so-called iron–sulfur complex (ISC) assembly machinery located in the mitochondrion. This machinery provides the cytoplasm with a still unknown sulfur component, which is then converted into iron–sulfur clusters via a cytosolic iron–sulfur protein assembly (CIA) machinery. Here, we investigated if a CIA machinery is present in mitochondrion-lacking PPCs. By using bioinformatic screens and in vivo-localizations of candidate proteins, we show that the presence of a PPC-specific CIA machinery correlates with the presence of a nucleomorph. Phylogenetic analyses of PPC- and host specific CIA components additionally indicate a complex evolution of the CIA machineries in organisms having plastids surrounded by four membranes.
Collapse
Affiliation(s)
- Christopher Grosche
- LOEWE Center for Synthetic Microbiology (Synmikro), Marburg, Germany.,Plant Cell Biology, Philipps University Marburg, Marburg, Germany
| | - Angelika Diehl
- LOEWE Center for Synthetic Microbiology (Synmikro), Marburg, Germany.,Laboratory for Cell Biology, Philipps University Marburg, Marburg, Germany
| | - Stefan A Rensing
- Plant Cell Biology, Philipps University Marburg, Marburg, Germany
| | - Uwe G Maier
- LOEWE Center for Synthetic Microbiology (Synmikro), Marburg, Germany.,Laboratory for Cell Biology, Philipps University Marburg, Marburg, Germany
| |
Collapse
|
10
|
Cavalier-Smith T. Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences. PROTOPLASMA 2018; 255:297-357. [PMID: 28875267 PMCID: PMC5756292 DOI: 10.1007/s00709-017-1147-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/18/2017] [Indexed: 05/18/2023]
Abstract
In 1981 I established kingdom Chromista, distinguished from Plantae because of its more complex chloroplast-associated membrane topology and rigid tubular multipartite ciliary hairs. Plantae originated by converting a cyanobacterium to chloroplasts with Toc/Tic translocons; most evolved cell walls early, thereby losing phagotrophy. Chromists originated by enslaving a phagocytosed red alga, surrounding plastids by two extra membranes, placing them within the endomembrane system, necessitating novel protein import machineries. Early chromists retained phagotrophy, remaining naked and repeatedly reverted to heterotrophy by losing chloroplasts. Therefore, Chromista include secondary phagoheterotrophs (notably ciliates, many dinoflagellates, Opalozoa, Rhizaria, heliozoans) or walled osmotrophs (Pseudofungi, Labyrinthulea), formerly considered protozoa or fungi respectively, plus endoparasites (e.g. Sporozoa) and all chromophyte algae (other dinoflagellates, chromeroids, ochrophytes, haptophytes, cryptophytes). I discuss their origin, evolutionary diversification, and reasons for making chromists one kingdom despite highly divergent cytoskeletons and trophic modes, including improved explanations for periplastid/chloroplast protein targeting, derlin evolution, and ciliary/cytoskeletal diversification. I conjecture that transit-peptide-receptor-mediated 'endocytosis' from periplastid membranes generates periplastid vesicles that fuse with the arguably derlin-translocon-containing periplastid reticulum (putative red algal trans-Golgi network homologue; present in all chromophytes except dinoflagellates). I explain chromist origin from ancestral corticates and neokaryotes, reappraising tertiary symbiogenesis; a chromist cytoskeletal synapomorphy, a bypassing microtubule band dextral to both centrioles, favoured multiple axopodial origins. I revise chromist higher classification by transferring rhizarian subphylum Endomyxa from Cercozoa to Retaria; establishing retarian subphylum Ectoreta for Foraminifera plus Radiozoa, apicomonad subclasses, new dinozoan classes Myzodinea (grouping Colpovora gen. n., Psammosa), Endodinea, Sulcodinea, and subclass Karlodinia; and ranking heterokont Gyrista as phylum not superphylum.
Collapse
|
11
|
Moog D. In Silico Tools for the Prediction of Protein Import into Secondary Plastids. Methods Mol Biol 2018; 1829:381-394. [PMID: 29987735 DOI: 10.1007/978-1-4939-8654-5_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The in silico identification of proteins targeting to secondary plastids is a difficult task. Such plastids are complex in structure and can be surrounded by up to four membranes, which have to be crossed during import. Nucleus-encoded plastidial preproteins in organisms with secondary plastids contain specific N-terminal targeting signals, the so-called bipartite targeting signal (BTS) sequences consisting of a classical signal peptide followed by a transit peptide-like sequence, mediating this intricate process. As these signal sequences differ significantly from transit peptides of plastid preproteins in plants and other organisms with primary plastids, existing in silico tools for primary plastid targeting prediction are not directly suitable to detect nucleus-encoded proteins destined for the import into secondary plastids. In this chapter I describe the current state-of-the-art methods to reliably predict proteins that might be imported into secondary plastids of red- and green-algal origin using either the "classical" approach, which involves a combination of bits of information produced by existing in silico tools, or, if available, via consulting specifically developed algorithms.
Collapse
Affiliation(s)
- Daniel Moog
- Laboratory for Cell Biology, Philipps University Marburg, Marburg, Germany.
| |
Collapse
|
12
|
Neumann N, Jeffares DC, Poole AM. Outsourcing the Nucleus: Nuclear Pore Complex Genes are no Longer Encoded in Nucleomorph Genomes. Evol Bioinform Online 2017. [DOI: 10.1177/117693430600200023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The nuclear pore complex (NPC) facilitates transport between nucleus and cytoplasm. The protein constituents of the NPC, termed nucleoporins (Nups), are conserved across a wide diversity of eukaryotes. In apparent exception to this, no nucleoporin genes have been identified in nucleomorph genomes. Nucleomorphs, nuclear remnants of once free-living eukaryotes, took up residence as secondary endosymbionts in cryptomonad and chlorarachniophyte algae. As these genomes are highly reduced, Nup genes may have been lost, or relocated to the host nucleus. However, Nup genes are often poorly conserved between species, so absence may be an artifact of low sequence similarity. We therefore constructed an evolutionary bioinformatic screen to establish whether the apparent absence of Nup genes in nucleomorph genomes is due to genuine absence or the inability of current methods to detect homologues. We searched green plant ( Arabidopsis and rice), green alga ( Chlamydomonas reinhardtii) and red alga ( Cyanidioschyzon merolae) genomes, plus two nucleomorph genomes ( Bigelowiella natans and Guillardia theta) with profile hidden Markov models (HMMs) from curated alignments of known vertebrate/yeast Nups. Since the plant, algal and nucleomorph genomes all belong to the kingdom Plantae, and are evolutionarily distant from the outgroup (vertebrate/yeast) training set, we use the plant and algal genomes as internal positive controls for the sensitivity of the searches in nucleomorph genomes. We find numerous Nup homologues in all plant and free-living algal species, but none in either nucleomorph genome. BLAST searches using identified plant and algal Nups also failed to detect nucleomorph homologues. We conclude that nucleomorph Nup genes have either been lost, being replaced by host Nup genes, or, that nucleomorph Nup genes have been transferred to the host nucleus twice independently; once in the evolution of the red algal nucleomorph and once in the green algal nucleomorph.
Collapse
Affiliation(s)
- Nadja Neumann
- Department of Molecular Biology and Functional Genomics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Daniel C. Jeffares
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, U.K
| | - Anthony M. Poole
- Department of Molecular Biology and Functional Genomics, Stockholm University, SE-106 91 Stockholm, Sweden
| |
Collapse
|
13
|
McFadden GI. The cryptomonad nucleomorph. PROTOPLASMA 2017; 254:1903-1907. [PMID: 28828570 DOI: 10.1007/s00709-017-1153-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 08/12/2017] [Indexed: 06/07/2023]
Abstract
The cryptomonad nucleomorph is a vestigial nucleus of a eukaryotic red alga engulfed by a phagotrophic protist and retained as a photosynthetic endosymbiont. This review recounts the initial discovery and subsequent characterisation of the cryptomonad nucleomorph focusing on the key role of Peter Sitte and his protégés in our understanding of secondary endosymbiosis to create complex plastids, one of the major transition events in the evolution of life on Earth.
Collapse
Affiliation(s)
- Geoffrey I McFadden
- School of BioSciences, University of Melbourne, Parkville, VIC, 3010, Australia.
- Botany School, University of Melbourne, Parkville, VIC, Australia.
| |
Collapse
|
14
|
Onuma R, Mishra N, Miyagishima SY. Regulation of chloroplast and nucleomorph replication by the cell cycle in the cryptophyte Guillardia theta. Sci Rep 2017; 7:2345. [PMID: 28539635 PMCID: PMC5443833 DOI: 10.1038/s41598-017-02668-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/13/2017] [Indexed: 01/08/2023] Open
Abstract
The chloroplasts of cryptophytes arose through a secondary endosymbiotic event in which a red algal endosymbiont was integrated into a previously nonphotosynthetic eukaryote. The cryptophytes retain a remnant of the endosymbiont nucleus (nucleomorph) that is replicated once in the cell cycle along with the chloroplast. To understand how the chloroplast, nucleomorph and host cell divide in a coordinated manner, we examined the expression of genes/proteins that are related to nucleomorph replication and chloroplast division as well as the timing of nuclear and nucleomorph DNA synthesis in the cryptophyte Guillardia theta. Nucleus-encoded nucleomorph HISTONE H2A mRNA specifically accumulated during the nuclear S phase. In contrast, nucleomorph-encoded genes/proteins that are related to nucleomorph replication and chloroplast division (FtsZ) are constantly expressed throughout the cell cycle. The results of this study and previous studies on chlorarachniophytes suggest that there was a common evolutionary pattern in which an endosymbiont lost its replication cycle-dependent transcription while cell-cycle-dependent transcriptional regulation of host nuclear genes came to restrict the timing of nucleomorph replication and chloroplast division.
Collapse
Affiliation(s)
- Ryo Onuma
- Department of Cell Genetics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka, 411-8540, Japan.
| | - Neha Mishra
- Department of Cell Genetics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka, 411-8540, Japan.,Department of Genetics, Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka, 411-8540, Japan
| | - Shin-Ya Miyagishima
- Department of Cell Genetics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka, 411-8540, Japan. .,Department of Genetics, Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka, 411-8540, Japan.
| |
Collapse
|
15
|
Davis A, Abbriano R, Smith SR, Hildebrand M. Clarification of Photorespiratory Processes and the Role of Malic Enzyme in Diatoms. Protist 2016; 168:134-153. [PMID: 28104538 DOI: 10.1016/j.protis.2016.10.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 10/03/2016] [Accepted: 10/08/2016] [Indexed: 11/20/2022]
Abstract
Evidence suggests that diatom photorespiratory metabolism is distinct from other photosynthetic eukaryotes in that there may be at least two routes for the metabolism of the photorespiratory metabolite glycolate. One occurs primarily in the mitochondria and is similar to the C2 photorespiratory pathway, and the other processes glycolate through the peroxisomal glyoxylate cycle. Genomic analysis has identified the presence of key genes required for glycolate oxidation, the glyoxylate cycle, and malate metabolism, however, predictions of intracellular localization can be ambiguous and require verification. This knowledge gap leads to uncertainties surrounding how these individual pathways operate, either together or independently, to process photorespiratory intermediates under different environmental conditions. Here, we combine in silico sequence analysis, in vivo protein localization techniques and gene expression patterns to investigate key enzymes potentially involved in photorespiratory metabolism in the model diatom Thalassiosira pseudonana. We demonstrate the peroxisomal localization of isocitrate lyase and the mitochondrial localization of malic enzyme and a glycolate oxidase. Based on these analyses, we propose an updated model for photorespiratory metabolism in T. pseudonana, as well as a mechanism by which C2 photorespiratory metabolism and its associated pathways may operate during silicon starvation and growth arrest.
Collapse
Affiliation(s)
- Aubrey Davis
- Marine Biology Research Division, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, U.S.A
| | - Raffaela Abbriano
- Marine Biology Research Division, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, U.S.A
| | - Sarah R Smith
- Integrative Oceanography Division, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, U.S.A.; J. Craig Venter Institute, La Jolla, CA, U.S.A
| | - Mark Hildebrand
- Marine Biology Research Division, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, U.S.A..
| |
Collapse
|
16
|
Sheiner L, Fellows JD, Ovciarikova J, Brooks CF, Agrawal S, Holmes ZC, Bietz I, Flinner N, Heiny S, Mirus O, Przyborski JM, Striepen B. Toxoplasma gondii Toc75 Functions in Import of Stromal but not Peripheral Apicoplast Proteins. Traffic 2015; 16:1254-69. [PMID: 26381927 DOI: 10.1111/tra.12333] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 09/14/2015] [Accepted: 09/14/2015] [Indexed: 01/09/2023]
Abstract
Apicomplexa are unicellular parasites causing important human and animal diseases, including malaria and toxoplasmosis. Most of these pathogens possess a relict but essential plastid, the apicoplast. The apicoplast was acquired by secondary endosymbiosis between a red alga and a flagellated eukaryotic protist. As a result the apicoplast is surrounded by four membranes. This complex structure necessitates a system of transport signals and translocons allowing nuclear encoded proteins to find their way to specific apicoplast sub-compartments. Previous studies identified translocons traversing two of the four apicoplast membranes. Here we provide functional support for the role of an apicomplexan Toc75 homolog in apicoplast protein transport. We identify two apicomplexan genes encoding Toc75 and Sam50, both members of the Omp85 protein family. We localize the respective proteins to the apicoplast and the mitochondrion of Toxoplasma and Plasmodium. We show that the Toxoplasma Toc75 is essential for parasite growth and that its depletion results in a rapid defect in the import of apicoplast stromal proteins while the import of proteins of the outer compartments is affected only as the secondary consequence of organelle loss. These observations along with the homology to Toc75 suggest a potential role in transport through the second innermost membrane.
Collapse
Affiliation(s)
- Lilach Sheiner
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA.,Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Justin D Fellows
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Jana Ovciarikova
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Carrie F Brooks
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Swati Agrawal
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Zachary C Holmes
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Irine Bietz
- Department of Parasitology, Faculty of Biology, Philipps University Marburg, Marburg, Germany
| | - Nadine Flinner
- Molecular Cell Biology of Plants, Biocenter N200, 3. OG, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Sabrina Heiny
- Department of Parasitology, Faculty of Biology, Philipps University Marburg, Marburg, Germany
| | - Oliver Mirus
- Molecular Cell Biology of Plants, Biocenter N200, 3. OG, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Jude M Przyborski
- Department of Parasitology, Faculty of Biology, Philipps University Marburg, Marburg, Germany
| | - Boris Striepen
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| |
Collapse
|
17
|
Moog D, Rensing SA, Archibald JM, Maier UG, Ullrich KK. Localization and Evolution of Putative Triose Phosphate Translocators in the Diatom Phaeodactylum tricornutum. Genome Biol Evol 2015; 7:2955-69. [PMID: 26454011 PMCID: PMC5635587 DOI: 10.1093/gbe/evv190] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The establishment of a metabolic connection between host and symbiont is a crucial step in the evolution of an obligate endosymbiotic relationship. Such was the case in the evolution of mitochondria and plastids. Whereas the mechanisms of metabolite shuttling between the plastid and host cytosol are relatively well studied in Archaeplastida—organisms that acquired photosynthesis through primary endosymbiosis—little is known about this process in organisms with complex plastids. Here, we focus on the presence, localization, and phylogeny of putative triose phosphate translocators (TPTs) in the complex plastid of diatoms. These proteins are thought to play an essential role in connecting endosymbiont and host metabolism via transport of carbohydrates generated by the photosynthesis machinery of the endosymbiont. We show that the complex plastid localized TPTs are monophyletic and present a model for how the initial metabolic link between host and endosymbiont might have been established in diatoms and other algae with complex red plastids and discuss its implications on the evolution of those lineages.
Collapse
Affiliation(s)
- Daniel Moog
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Germany Present address: Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | - John M Archibald
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada Program in Integrated Microbial Biodiversity, Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Uwe G Maier
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Germany Laboratory for Cell Biology, Philipps University Marburg, Germany
| | | |
Collapse
|
18
|
Abstract
Many protists with high ecological and medical relevance harbor plastids surrounded by four membranes. Thus, nucleus-encoded proteins of these complex plastids have to traverse these barriers. Here we report on the identification of the protein translocators located in two of the plastid surrounding membranes and present recent findings on the mechanisms of protein import into the plastids of diatoms.
Collapse
|
19
|
Gile GH, Moog D, Slamovits CH, Maier UG, Archibald JM. Dual Organellar Targeting of Aminoacyl-tRNA Synthetases in Diatoms and Cryptophytes. Genome Biol Evol 2015; 7:1728-42. [PMID: 25994931 PMCID: PMC4494062 DOI: 10.1093/gbe/evv095] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The internal compartmentation of eukaryotic cells not only allows separation of biochemical processes but it also creates the requirement for systems that can selectively transport proteins across the membrane boundaries. Although most proteins function in a single subcellular compartment, many are able to enter two or more compartments, a phenomenon known as dual or multiple targeting. The aminoacyl-tRNA synthetases (aaRSs), which catalyze the ligation of tRNAs to their cognate amino acids, are particularly prone to functioning in multiple subcellular compartments. They are essential for translation, so they are required in every compartment where translation takes place. In diatoms, there are three such compartments, the plastid, the mitochondrion, and the cytosol. In cryptophytes, translation also takes place in the periplastid compartment (PPC), which is the reduced cytoplasm of the plastid’s red algal ancestor and which retains a reduced red algal nucleus. We searched the organelle and nuclear genomes of the cryptophyte Guillardia theta and the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana for aaRS genes and found an insufficient number of genes to provide each compartment with a complete set of aaRSs. We therefore inferred, with support from localization predictions, that many aaRSs are dual targeted. We tested four of the predicted dual targeted aaRSs with green fluorescent protein fusion localizations in P. tricornutum and found evidence for dual targeting to the mitochondrion and plastid in P. tricornutum and G. theta, and indications for dual targeting to the PPC and cytosol in G. theta. This is the first report of dual targeting in diatoms or cryptophytes.
Collapse
Affiliation(s)
- Gillian H Gile
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Daniel Moog
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Germany Present address: Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Claudio H Slamovits
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada Program in Integrated Microbial Biodiversity, Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Uwe-G Maier
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Germany Laboratory for Cell Biology, Philipps University Marburg, Germany
| | - John M Archibald
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada Program in Integrated Microbial Biodiversity, Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| |
Collapse
|
20
|
In vivo Localization Studies in the Stramenopile Alga Nannochloropsis oceanica. Protist 2015; 166:161-71. [DOI: 10.1016/j.protis.2015.01.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 01/08/2015] [Accepted: 01/12/2015] [Indexed: 01/21/2023]
|
21
|
Gruber A, Rocap G, Kroth PG, Armbrust EV, Mock T. Plastid proteome prediction for diatoms and other algae with secondary plastids of the red lineage. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:519-28. [PMID: 25438865 PMCID: PMC4329603 DOI: 10.1111/tpj.12734] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 11/19/2014] [Accepted: 11/26/2014] [Indexed: 05/19/2023]
Abstract
The plastids of ecologically and economically important algae from phyla such as stramenopiles, dinoflagellates and cryptophytes were acquired via a secondary endosymbiosis and are surrounded by three or four membranes. Nuclear-encoded plastid-localized proteins contain N-terminal bipartite targeting peptides with the conserved amino acid sequence motif 'ASAFAP'. Here we identify the plastid proteomes of two diatoms, Thalassiosira pseudonana and Phaeodactylum tricornutum, using a customized prediction tool (ASAFind) that identifies nuclear-encoded plastid proteins in algae with secondary plastids of the red lineage based on the output of SignalP and the identification of conserved 'ASAFAP' motifs and transit peptides. We tested ASAFind against a large reference dataset of diatom proteins with experimentally confirmed subcellular localization and found that the tool accurately identified plastid-localized proteins with both high sensitivity and high specificity. To identify nucleus-encoded plastid proteins of T. pseudonana and P. tricornutum we generated optimized sets of gene models for both whole genomes, to increase the percentage of full-length proteins compared with previous assembly model sets. ASAFind applied to these optimized sets revealed that about 8% of the proteins encoded in their nuclear genomes were predicted to be plastid localized and therefore represent the putative plastid proteomes of these algae.
Collapse
Affiliation(s)
- Ansgar Gruber
- Fachbereich Biologie, Universität KonstanzKonstanz, 78457, Germany
| | - Gabrielle Rocap
- School of Oceanography, Center for Environmental Genomics, University of WashingtonSeattle, WA, 98195, USA
| | - Peter G Kroth
- Fachbereich Biologie, Universität KonstanzKonstanz, 78457, Germany
| | - E Virginia Armbrust
- School of Oceanography, Center for Environmental Genomics, University of WashingtonSeattle, WA, 98195, USA
| | - Thomas Mock
- School of Environmental Sciences, University of East AngliaNorwich Research Park, NR4 7TJ, Norwich, UK
- *
For correspondence (e-mail )
| |
Collapse
|
22
|
Mernberger M, Moog D, Stork S, Zauner S, Maier UG, Hüllermeier E. Protein sub-cellular localization prediction for special compartments via optimized time series distances. J Bioinform Comput Biol 2014; 12:1350016. [PMID: 24467755 DOI: 10.1142/s0219720013500169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Predicting the sub-cellular localization of proteins is an important task in bioinformatics, for which many standard prediction tools are available. While these tools are powerful in general and capable of predicting protein localization for the most common compartments, their performance strongly depends on the organism of interest. More importantly, there are special compartments, such as the apicoplast of apicomplexan parasites, for which these tools cannot provide a prediction at all. In the absence of a highly conserved targeting signal, even motif searches may not be able to provide a lead for the accurate prediction of protein localization for a compartment of interest. In order to approach difficult cases of that kind, we propose an alternative method that complements existing approaches by using a more targeted protein sequence model. Moreover, our method makes use of (weighted) measures for time series comparison. To demonstrate its performance, we use this method for predicting localization in special compartments of three different species, for which existing methods yield only sub-optimal results. As shown experimentally, our method is indeed capable of producing reliable predictions of sub-cellular localization for difficult cases, i.e. if training data is scarce and a potential protein targeting signal may not be well conserved.
Collapse
Affiliation(s)
- Marco Mernberger
- Department of Mathematics and Computer Science, University of Marburg, Hans-Meerwein Straße, Marburg 35032, Germany
| | | | | | | | | | | |
Collapse
|
23
|
Samukawa M, Shen C, Hopkinson BM, Matsuda Y. Localization of putative carbonic anhydrases in the marine diatom, Thalassiosira pseudonana. PHOTOSYNTHESIS RESEARCH 2014; 121:235-49. [PMID: 24414291 DOI: 10.1007/s11120-014-9967-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 12/31/2013] [Indexed: 05/19/2023]
Abstract
Thirteen putative carbonic anhydrase (CA) genes have been identified in the marine multipolar centric diatom, Thalassiosira pseudonana, and two of these CAs have been localized previously. The first, an alpha CA (TpαCA1), was localized in the chloroplast stroma; the second, a zeta-type CA (TpζCA1), was localized to the periplasmic space. In the present study, cloning and localization of the remaining CAs were carried out. TpγCA2, TpγCA3, TpγCA4, TpγCA5, TpδCA1, TpδCA2, TpδCA3, and TpζCA1 were responsive to CO2 availability at the transcriptional level, being significantly reduced in cells grown at 0.4 % CO2, whereas TpαCA1, TpαCA2, TpαCA3, TpγCA1, and TpδCA4 transcript levels were constitutive with respect to CO2 concentration. Full-length cDNAs for TpγCA1, TpγCA2, TpγCA3, TpγCA4, TpδCA1, and TpδCA2 were isolated and fused with the enhanced-green fluorescent gene at their 3' termini. These GFP-fusion constructs were transformed into T. pseudonana, and the resulting GFP fusion products were localized using fluorescence microscopy. The δ-type TpδCA1 was localized on the periphery of the cell, strongly suggesting localization to the periplasmic space or the frustule. The δ-type TpδCA3 and the γ-type TpγCA2 were, respectively, localized in a periplastidal compartment and the cytosol. The δ-type TpδCA2, and the γ-types TpγCA1, 3, and 4 were localized in the mitochondria. The distribution of CAs in T. pseudonana contrasts notably with that of the raphid pennate diatom P. tricornutum, with likely consequences for CCM function including modes of CO2 acquisition, regions in which DIC is accumulated, and needs for minimizing CO2 leakage from the chloroplast.
Collapse
Affiliation(s)
- Mio Samukawa
- Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan
| | | | | | | |
Collapse
|
24
|
Tanaka R, Kikutani S, Mahardika A, Matsuda Y. Localization of enzymes relating to C4 organic acid metabolisms in the marine diatom, Thalassiosira pseudonana. PHOTOSYNTHESIS RESEARCH 2014; 121:251-63. [PMID: 24414292 DOI: 10.1007/s11120-014-9968-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 12/31/2013] [Indexed: 05/23/2023]
Abstract
In the genome of the marine diatom-Thalassiosira pseudonana, there are several putative genes encoding enzymes potentially constitute a classical C4 type biochemical CO2-concentrating mechanism. Two genes encode a carboxylation enzyme phosphoenolpyruvate carboxylase (PEPC)1 and PEPC2; and another two encode decarboxylation enzymes, NAD(+)-dependent malic enzyme (NAD-ME) and phosphoenolpyruvate carboxykinase (PEPCK). These genes were tagged by the enhanced-green fluorescence protein, egfp, ligated in the transformation vector, and transformed into the cells of T. pseudonana for localization of GFP fusion products. The PEPC1:GFP fusion was localized at the matrix of the periplastidal compartment, while the PEPC2:GFP fusion was localized at the mitochondria. The NAD-ME:GFP fusion was localized in the cytosol and the PEPCK:GFP fusion at the mitochondria. The transcripts level of NAD-ME was extremely low, and PEPCK transcript was significantly induced under the dark, suggesting that PEPCK is involved in the dark metabolism such as respiration and amino acid metabolism in the mitochondria. Treatments of low-CO2grown T. pseudonana cells with inhibitors for PEPCK and PEPC efficiently dissipated the maximum rate of photosynthesis while these treatments did not affect high-affinity photosynthesis. These data strongly suggest that classical C4 enzymes play little role in the CCM in T. pseudonana.
Collapse
Affiliation(s)
- Rie Tanaka
- Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan
| | | | | | | |
Collapse
|
25
|
Overkamp KE, Gasper R, Kock K, Herrmann C, Hofmann E, Frankenberg-Dinkel N. Insights into the biosynthesis and assembly of cryptophycean phycobiliproteins. J Biol Chem 2014; 289:26691-26707. [PMID: 25096577 DOI: 10.1074/jbc.m114.591131] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Phycobiliproteins are employed by cyanobacteria, red algae, glaucophytes, and cryptophytes for light-harvesting and consist of apoproteins covalently associated with open-chain tetrapyrrole chromophores. Although the majority of organisms assemble the individual phycobiliproteins into larger aggregates called phycobilisomes, members of the cryptophytes use a single type of phycobiliprotein that is localized in the thylakoid lumen. The cryptophyte Guillardia theta (Gt) uses phycoerythrin PE545 utilizing the uncommon chromophore 15,16-dihydrobiliverdin (DHBV) in addition to phycoerythrobilin (PEB). Both the biosynthesis and the attachment of chromophores to the apophycobiliprotein have not yet been investigated for cryptophytes. In this study, we identified and characterized enzymes involved in PEB biosynthesis. In addition, we present the first in-depth biochemical characterization of a eukaryotic phycobiliprotein lyase (GtCPES). Plastid-encoded HO (GtHo) was shown to convert heme into biliverdin IXα providing the substrate with a putative nucleus-encoded DHBV:ferredoxin oxidoreductase (GtPEBA). A PEB:ferredoxin oxidoreductase (GtPEBB) was found to convert DHBV to PEB, which is the substrate for the phycobiliprotein lyase GtCPES. The x-ray structure of GtCPES was solved at 2.0 Å revealing a 10-stranded β-barrel with a modified lipocalin fold. GtCPES is an S-type lyase specific for binding of phycobilins with reduced C15=C16 double bonds (DHBV and PEB). Site-directed mutagenesis identified residues Glu-136 and Arg-146 involved in phycobilin binding. Based on the crystal structure, a model for the interaction of GtCPES with the apophycobiliprotein CpeB is proposed and discussed.
Collapse
Affiliation(s)
- Kristina E Overkamp
- Physiology of Microorganisms, Faculty for Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Raphael Gasper
- Protein Crystallography, Faculty for Biology and Biotechnology, and Ruhr University Bochum, 44780 Bochum, Germany
| | - Klaus Kock
- Physical Chemistry I, Protein Interactions, Faculty for Chemistry and Biochemistry, Ruhr University Bochum, 44780 Bochum, Germany
| | - Christian Herrmann
- Physical Chemistry I, Protein Interactions, Faculty for Chemistry and Biochemistry, Ruhr University Bochum, 44780 Bochum, Germany
| | - Eckhard Hofmann
- Protein Crystallography, Faculty for Biology and Biotechnology, and Ruhr University Bochum, 44780 Bochum, Germany
| | - Nicole Frankenberg-Dinkel
- Physiology of Microorganisms, Faculty for Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany.
| |
Collapse
|
26
|
Abstract
Diatoms are microalgae that possess so-called "complex plastids," which evolved by secondary endosymbiosis and are surrounded by four membranes. Thus, in contrast to primary plastids, which are surrounded by only two membranes, nucleus-encoded proteins of complex plastids face additional barriers, i.e., during evolution, mechanisms had to evolve to transport preproteins across all four membranes. This study reveals that there exist glycoproteins not only in primary but also in complex plastids, making transport issues even more complicated, as most translocation machineries are not believed to be able to transport bulky proteins. We show that plastidal reporter proteins with artificial N-glycosylation sites are indeed glycosylated during transport into the complex plastid of the diatom Phaeodactylum tricornutum. Additionally, we identified five endogenous glycoproteins, which are transported into different compartments of the complex plastid. These proteins get N-glycosylated during transport across the outermost plastid membrane and thereafter are transported across the second, third, and fourth plastid membranes in the case of stromal proteins. The results of this study provide insights into the evolutionary pressure on translocation mechanisms and pose unique questions on the operating mode of well-known transport machineries like the translocons of the outer/inner chloroplast membranes (Toc/Tic).
Collapse
|
27
|
Hopkins JF, Spencer DF, Laboissiere S, Neilson JAD, Eveleigh RJM, Durnford DG, Gray MW, Archibald JM. Proteomics reveals plastid- and periplastid-targeted proteins in the chlorarachniophyte alga Bigelowiella natans. Genome Biol Evol 2013; 4:1391-406. [PMID: 23221610 PMCID: PMC3542566 DOI: 10.1093/gbe/evs115] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Chlorarachniophytes are unicellular marine algae with plastids (chloroplasts) of secondary endosymbiotic origin. Chlorarachniophyte cells retain the remnant nucleus (nucleomorph) and cytoplasm (periplastidial compartment, PPC) of the green algal endosymbiont from which their plastid was derived. To characterize the diversity of nucleus-encoded proteins targeted to the chlorarachniophyte plastid, nucleomorph, and PPC, we isolated plastid–nucleomorph complexes from the model chlorarachniophyte Bigelowiella natans and subjected them to high-pressure liquid chromatography-tandem mass spectrometry. Our proteomic analysis, the first of its kind for a nucleomorph-bearing alga, resulted in the identification of 324 proteins with 95% confidence. Approximately 50% of these proteins have predicted bipartite leader sequences at their amino termini. Nucleus-encoded proteins make up >90% of the proteins identified. With respect to biological function, plastid-localized light-harvesting proteins were well represented, as were proteins involved in chlorophyll biosynthesis. Phylogenetic analyses revealed that many, but by no means all, of the proteins identified in our proteomic screen are of apparent green algal ancestry, consistent with the inferred evolutionary origin of the plastid and nucleomorph in chlorarachniophytes.
Collapse
Affiliation(s)
- Julia F Hopkins
- Department of Biochemistry and Molecular Biology, Dalhousie University, Nova Scotia, Canada
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Poulsen N, Scheffel A, Sheppard VC, Chesley PM, Kröger N. Pentalysine clusters mediate silica targeting of silaffins in Thalassiosira pseudonana. J Biol Chem 2013; 288:20100-9. [PMID: 23720751 DOI: 10.1074/jbc.m113.469379] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biological formation of inorganic materials (biomineralization) often occurs in specialized intracellular vesicles. Prominent examples are diatoms, a group of single-celled eukaryotic microalgae that produce their SiO2 (silica)-based cell walls within intracellular silica deposition vesicles (SDVs). SDVs contain protein-based organic matrices that control silica formation, resulting in species specifically nanopatterned biosilica, an organic-inorganic composite material. So far no information is available regarding the molecular mechanisms of SDV biogenesis. Here we have investigated by fluorescence microscopy and subcellular membrane fractionation the intracellular transport of silaffin Sil3. Silaffins are a group of phosphoproteins constituting the main components of the organic matrix of diatom biosilica. We demonstrate that the N-terminal signal peptide of Sil3 mediates import into a specific subregion of the endoplasmic reticulum. Additional segments from the mature part of Sil3 are required to reach post-endoplasmic reticulum compartments. Further transport of Sil3 and incorporation into the biosilica (silica targeting) require protein segments that contain a high density of modified lysine residues and phosphoserines. Silica targeting of Sil3 is not dependent on a particular peptide sequence, yet a lysine-rich 12-14-amino acid peptide motif (pentalysine cluster), which is conserved in all silaffins, strongly promotes silica targeting. The results of the present work provide the first insight into the molecular mechanisms for biogenesis of mineral-forming vesicles from an eukaryotic organism.
Collapse
|
29
|
Moore CE, Curtis B, Mills T, Tanifuji G, Archibald JM. Nucleomorph genome sequence of the cryptophyte alga Chroomonas mesostigmatica CCMP1168 reveals lineage-specific gene loss and genome complexity. Genome Biol Evol 2013; 4:1162-75. [PMID: 23042551 PMCID: PMC3514955 DOI: 10.1093/gbe/evs090] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cryptophytes are a diverse lineage of marine and freshwater, photosynthetic and secondarily nonphotosynthetic algae that acquired their plastids (chloroplasts) by “secondary” (i.e., eukaryote–eukaryote) endosymbiosis. Consequently, they are among the most genetically complex cells known and have four genomes: a mitochondrial, plastid, “master” nuclear, and residual nuclear genome of secondary endosymbiotic origin, the so-called “nucleomorph” genome. Sequenced nucleomorph genomes are ∼1,000-kilobase pairs (Kbp) or less in size and are comprised of three linear, compositionally biased chromosomes. Although most functionally annotated nucleomorph genes encode proteins involved in core eukaryotic processes, up to 40% of the genes in these genomes remain unidentifiable. To gain insight into the function and evolutionary fate of nucleomorph genomes, we used 454 and Illumina technologies to completely sequence the nucleomorph genome of the cryptophyte Chroomonas mesostigmatica CCMP1168. At 702.9 Kbp in size, the C. mesostigmatica nucleomorph genome is the largest and the most complex nucleomorph genome sequenced to date. Our comparative analyses reveal the existence of a highly conserved core set of genes required for maintenance of the cryptophyte nucleomorph and plastid, as well as examples of lineage-specific gene loss resulting in differential loss of typical eukaryotic functions, e.g., proteasome-mediated protein degradation, in the four cryptophyte lineages examined.
Collapse
Affiliation(s)
- Christa E Moore
- Integrated Microbial Biodiversity Program, Canadian Institute for Advanced Research, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | | | | | | |
Collapse
|
30
|
Keeling PJ. The number, speed, and impact of plastid endosymbioses in eukaryotic evolution. ANNUAL REVIEW OF PLANT BIOLOGY 2013; 64:583-607. [PMID: 23451781 DOI: 10.1146/annurev-arplant-050312-120144] [Citation(s) in RCA: 271] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Plastids (chloroplasts) have long been recognized to have originated by endosymbiosis of a cyanobacterium, but their subsequent evolutionary history has proved complex because they have also moved between eukaryotes during additional rounds of secondary and tertiary endosymbioses. Much of this history has been revealed by genomic analyses, but some debates remain unresolved, in particular those relating to secondary red plastids of the chromalveolates, especially cryptomonads. Here, I examine several fundamental questions and assumptions about endosymbiosis and plastid evolution, including the number of endosymbiotic events needed to explain plastid diversity, whether the genetic contribution of the endosymbionts to the host genome goes far beyond plastid-targeted genes, and whether organelle origins are best viewed as a singular transition involving one symbiont or as a gradual transition involving a long line of transient food/symbionts. I also discuss a possible link between transporters and the evolution of protein targeting in organelle integration.
Collapse
Affiliation(s)
- Patrick J Keeling
- Canadian Institute for Advanced Research and Department of Botany, University of British Columbia, Vancouver, Canada V6T 1Z4.
| |
Collapse
|
31
|
Sheiner L, Striepen B. Protein sorting in complex plastids. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:352-9. [PMID: 22683761 DOI: 10.1016/j.bbamcr.2012.05.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 05/25/2012] [Accepted: 05/28/2012] [Indexed: 12/11/2022]
Abstract
Taming a cyanobacterium in a pivitol event of endosymbiosis brought photosynthesis to eukaryotes, and gave rise to the plastids found in glaucophytes, red and green algae, and the descendants of the latter, the plants. Ultrastructural as well as molecular research over the last two decades has demonstrated that plastids have enjoyed surprising lateral mobility across the tree of life. Numerous independent secondary and tertiary endosymbiosis have led to a spread of plastids into a variety of, up to that point, non-photosynthetic lineages. Happily eating and subsequently domesticating one another protists conquered a wide variety of ecological niches. The elaborate evolution of secondary, or complex, plastids is reflected in the numerous membranes that bound them (three or four compared to the two membranes of the primary plastids). Gene transfer to the host nucleus is a hallmark of endosymbiosis and provides centralized cellular control. Here we review how these proteins find their way back into the stroma of the organelle and describe the advances in the understanding of the molecular mechanisms that allow protein translocation across four membranes. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
Collapse
Affiliation(s)
- Lilach Sheiner
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA 30602, USA.
| | | |
Collapse
|
32
|
Ghoshroy S, Robertson DL. MOLECULAR EVOLUTION OF GLUTAMINE SYNTHETASE II AND III IN THE CHROMALVEOLATES(1). JOURNAL OF PHYCOLOGY 2012; 48:768-783. [PMID: 27011094 DOI: 10.1111/j.1529-8817.2012.01169.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Glutamine synthetase (GS) is encoded by three distinct gene families (GSI, GSII, and GSIII) that are broadly distributed among the three domains of life. Previous studies established that GSII and GSIII isoenzymes were expressed in diatoms; however, less is known about the distribution and evolution of the gene families in other chromalveolate lineages. Thus, GSII cDNA sequences were isolated from three cryptophytes (Guillardia theta D. R. A. Hill et Wetherbee, Cryptomonas phaseolus Skuja, and Pyrenomonas helgolandii Santore), and GSIII was sequenced from G. theta. Red algal GSII sequences were obtained from Bangia atropurpurea (Mertens ex Roth) C. Agardh; Compsopogon caeruleus (Balbis ex C. Agardh) Mont.; Flintiella sanguinaria F. D. Ott and Porphyridium aerugineum Geitler; Rhodella violacea (Kornmann) Wehrmeyer and Dixoniella grisea (Geitler) J. L. Scott, S. T. Broadwater, B. D. Saunders, J. P. Thomas et P. W. Gabrielson; and Stylonema alsidii (Zanardini) K. M. Drew. In Bayesian inference and maximum-likelihood (ML) phylogenetic analyses, chromalveolate GSII sequences formed a weakly supported clade that nested among sequences from glaucophytes, red algae, green algae, and plants. Red algal GSII sequences formed two distinct clades. The largest clade contained representatives from the Cyanidiophytina and Rhodophytina and grouped with plants and green algae. The smaller clade (C. caeruleus, Porphyra yezoensis, and S. alsidii) nested within the chromalveolates, although its placement was unresolved. Chromalveolate GSIII sequences formed a well-supported clade in Bayesian and ML phylogenies, and mitochondrial transit peptides were identified in many of the sequences. There was strong support for a stramenopile-haptophyte-cryptophyte GSIII clade in which the cryptophyte sequence diverged from the deepest node. Overall, the evolutionary history of the GS gene families within the algae is complex with evidence for the presence of orthologous and paralogous sequences, ancient and recent gene duplications, gene losses and replacements, and the potential for both endosymbiotic and lateral gene transfers.
Collapse
Affiliation(s)
- Sohini Ghoshroy
- Biology Department, Clark University, 950, Main Street, Worcester, MA 01610, USA
| | - Deborah L Robertson
- Biology Department, Clark University, 950, Main Street, Worcester, MA 01610, USA
| |
Collapse
|
33
|
Gross J, Bhattacharya D, Pelletreau KN, Rumpho ME, Reyes-Prieto A. Secondary and Tertiary Endosymbiosis and Kleptoplasty. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2012. [DOI: 10.1007/978-94-007-2920-9_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
34
|
Woehle C, Dagan T, Martin WF, Gould SB. Red and problematic green phylogenetic signals among thousands of nuclear genes from the photosynthetic and apicomplexa-related Chromera velia. Genome Biol Evol 2011; 3:1220-30. [PMID: 21965651 PMCID: PMC3205606 DOI: 10.1093/gbe/evr100] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/22/2011] [Indexed: 11/14/2022] Open
Abstract
The photosynthetic and basal apicomplexan Chromera velia was recently described, expanding the membership of this otherwise nonphotosynthetic group of parasite protists. Apicomplexans are alveolates with secondary plastids of red algal origin, but the evolutionary history of their nuclear genes is still actively discussed. Using deep sequencing of expressed genes, we investigated the phylogenetic affinities of a stringent filtered set of 3,151 expressed sequence tag-contigs by generating clusters with eukaryotic homologs and constructing phylogenetic trees and networks. The phylogenetic positioning of this alveolate alga was determined and sets of phyla-specific proteins extracted. Phylogenetic trees provided conflicting signals, with 444 trees grouping C. velia with the apicomplexans but 354 trees grouping C. velia with the alveolate oyster pathogen Perkinsus marinus, the latter signal being reinforced from the analysis of shared genes and overall sequence similarity. Among the 513 C. velia nuclear genes that reflect a photosynthetic ancestry and for which nuclear homologs were available both from red and green lineages, 263 indicated a red photosynthetic ancestry, whereas 250 indicated a green photosynthetic ancestry. The same 1:1 signal ratio was found among the putative 255 nuclear-encoded plastid proteins identified. This finding of red and green signals for the alveolate mirrors the result observed in the heterokont lineage and supports a common but not necessarily single origin for the plastid in heterokonts and alveolates. The inference of green endosymbiosis preceding red plastid acquisition in these lineages leads to worryingly complicated evolutionary scenarios, prompting the search for other explanations for the green phylogenetic signal and the amount of hosts involved.
Collapse
Affiliation(s)
| | | | | | - Sven B. Gould
- Molecular Evolution (Botanik III), Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| |
Collapse
|
35
|
Kořený L, Sobotka R, Janouškovec J, Keeling PJ, Oborník M. Tetrapyrrole synthesis of photosynthetic chromerids is likely homologous to the unusual pathway of apicomplexan parasites. THE PLANT CELL 2011; 23:3454-3462. [PMID: 21963666 PMCID: PMC3203424 DOI: 10.1105/tpc.111.089102] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/07/2011] [Accepted: 09/19/2011] [Indexed: 05/31/2023]
Abstract
Most photosynthetic eukaryotes synthesize both heme and chlorophyll via a common tetrapyrrole biosynthetic pathway starting from glutamate. This pathway was derived mainly from cyanobacterial predecessor of the plastid and differs from the heme synthesis of the plastid-lacking eukaryotes. Here, we show that the coral-associated alveolate Chromera velia, the closest known photosynthetic relative to Apicomplexa, possesses a tetrapyrrole pathway that is homologous to the unusual pathway of apicomplexan parasites. We also demonstrate that, unlike other eukaryotic phototrophs, Chromera synthesizes chlorophyll from glycine and succinyl-CoA rather than glutamate. Our data shed light on the evolution of the heme biosynthesis in parasitic Apicomplexa and photosynthesis-related biochemical processes in their ancestors.
Collapse
Affiliation(s)
- Luděk Kořený
- Institute of Parasitology, Biology Centre, Academy of Sciences of the Czech Republic, and Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Roman Sobotka
- Institute of Microbiology, Academy of Sciences of the Czech Republic, 37981 Třeboň, Czech Republic
| | - Jan Janouškovec
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Patrick J. Keeling
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Miroslav Oborník
- Institute of Parasitology, Biology Centre, Academy of Sciences of the Czech Republic, and Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
- Institute of Microbiology, Academy of Sciences of the Czech Republic, 37981 Třeboň, Czech Republic
| |
Collapse
|
36
|
Tachibana M, Allen AE, Kikutani S, Endo Y, Bowler C, Matsuda Y. Localization of putative carbonic anhydrases in two marine diatoms, Phaeodactylum tricornutum and Thalassiosira pseudonana. PHOTOSYNTHESIS RESEARCH 2011; 109:205-21. [PMID: 21365259 DOI: 10.1007/s11120-011-9634-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 02/13/2011] [Indexed: 05/12/2023]
Abstract
It is believed that intracellular carbonic anhydrases (CAs) are essential components of carbon concentrating mechanisms in microalgae. In this study, putative CA-encoding genes were identified in the genome sequences of the marine diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana. Subsequently, the subcellular localizations of the encoded proteins were determined. Nine and thirteen CA sequences were found in the genomes of P. tricornutum and T. pseudonana, respectively. Two of the β-CA genes in P. tricornutum corresponded to ptca1 and ptca2 identified previously. Immunostaining transmission electron microscopy of a PtCA1:YFP fusion expressed in the cells of P. tricornutum clearly showed the localization of PtCA1 within the central part of the pyrenoid structure in the chloroplast. Besides these two β-CA genes, P. tricornutum likely contains five α- and two γ-CA genes, whereas T. pseudonana has three α-, five γ-, four δ-, and one ζ-CA genes. Semi-quantitative reverse transcription PCR performed on mRNA from the two diatoms grown in changing light and CO(2) conditions revealed that levels of six putative α- and γ-CA mRNAs in P. tricornutum did not change between cells grown in air-level CO(2) and 5% CO(2). However, mRNA levels of one putative α-CA gene, CA-VII in P. tricornutum, were reduced in the dark compared to that in the light. In T. pseudonana, mRNA accumulation levels of putative α-CA (CA-1), ζ-CA (CA-3) and δ-CA (CA-7) were analyzed and all levels found to be significantly reduced when cells were grown in 0.16% CO(2). Intercellular localizations of eight putative CAs were analyzed by expressing GFP fusion in P. tricornutum and T. pseudonana. In P. tricornutum, CA-I and II localized in the periplastidial compartment, CA-III, VI, VII were found in the chloroplast endoplasmic reticulum, and CA-VIII was localized in the mitochondria. On the other hand, T. pseudonana CA-1 localized in the stroma and CA-3 was found in the periplasm. These results suggest that CAs are constitutively present in the four chloroplastic membrane systems in P. tricornutum and that CO(2) responsive CAs occur in the pyrenoid of P. tricornutum, and in the stroma and periplasm of T. pseudonana.
Collapse
Affiliation(s)
- Masaaki Tachibana
- Department of Bioscience, School of Science and Technology, Kwansei Gakuin University,Sanda, Hyogo, Japan
| | | | | | | | | | | |
Collapse
|
37
|
Moog D, Stork S, Zauner S, Maier UG. In silico and in vivo investigations of proteins of a minimized eukaryotic cytoplasm. Genome Biol Evol 2011; 3:375-82. [PMID: 21498883 PMCID: PMC3101018 DOI: 10.1093/gbe/evr031] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Algae with secondary plastids such as diatoms maintain two different eukaryotic cytoplasms. One of them, the so-called periplastidal compartment (PPC), is the naturally minimized cytoplasm of a eukaryotic endosymbiont. In order to investigate the protein composition of the PPC of diatoms, we applied knowledge of the targeting signals of PPC-directed proteins in searches of the genome data for proteins acting in the PPC and proved their in vivo localization via expressing green fluorescent protein (GFP) fusions. Our investigation increased the knowledge of the protein content of the PPC approximately 3-fold and thereby indicated that this narrow compartment was functionally reduced to some important cellular functions with nearly no housekeeping biochemical pathways.
Collapse
Affiliation(s)
- Daniel Moog
- LOEWE-Zentrum für Synthetische Mikrobiologie (SynMikro), Hans-Meerwein-Strasse, Marburg, Germany
| | | | | | | |
Collapse
|
38
|
Felsner G, Sommer MS, Gruenheit N, Hempel F, Moog D, Zauner S, Martin W, Maier UG. ERAD components in organisms with complex red plastids suggest recruitment of a preexisting protein transport pathway for the periplastid membrane. Genome Biol Evol 2010; 3:140-50. [PMID: 21081314 PMCID: PMC3045029 DOI: 10.1093/gbe/evq074] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The plastids of cryptophytes, haptophytes, and heterokontophytes (stramenopiles) (together once known as chromists) are surrounded by four membranes, reflecting the origin of these plastids through secondary endosymbiosis. They share this trait with apicomplexans, which are alveolates, the plastids of which have been suggested to stem from the same secondary symbiotic event and therefore form a phylogenetic clade, the chromalveolates. The chromists are quantitatively the most important eukaryotic contributors to primary production in marine ecosystems. The mechanisms of protein import across their four plastid membranes are still poorly understood. Components of an endoplasmic reticulum-associated degradation (ERAD) machinery in cryptophytes, partially encoded by the reduced genome of the secondary symbiont (the nucleomorph), are implicated in protein transport across the second outermost plastid membrane. Here, we show that the haptophyte Emiliania huxleyi, like cryptophytes, stramenopiles, and apicomplexans, possesses a nuclear-encoded symbiont-specific ERAD machinery (SELMA, symbiont-specific ERAD-like machinery) in addition to the host ERAD system, with targeting signals that are able to direct green fluorescent protein or yellow fluorescent protein to the predicted cellular localization in transformed cells of the stramenopile Phaeodactylum tricornutum. Phylogenies of the duplicated ERAD factors reveal that all SELMA components trace back to a red algal origin. In contrast, the host copies of cryptophytes and haptophytes associate with the green lineage to the exclusion of stramenopiles and alveolates. Although all chromalveolates with four membrane-bound plastids possess the SELMA system, this has apparently not arisen in a single endosymbiotic event. Thus, our data do not support the chromalveolate hypothesis.
Collapse
Affiliation(s)
- Gregor Felsner
- Department of Cell Biology, Philipps University of Marburg, Marburg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Hirakawa Y, Ishida KI. Internal plastid-targeting signal found in a RubisCO small subunit protein of a chlorarachniophyte alga. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:402-410. [PMID: 21049565 DOI: 10.1111/j.1365-313x.2010.04334.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In all plants and algae, most plastid proteins are encoded by the nuclear genome and, consequently, need to be transported into plastids across multiple membranes. In organisms with secondary plastids, which evolved by secondary endosymbioses, and are surrounded by three or four envelope membranes, precursors of nuclear-encoded plastid proteins generally have an N-terminal bipartite targeting sequence that consists of an endoplasmic reticulum (ER)-targeting signal peptide (SP) and a transit peptide-like (TPL) sequence. The bipartite targeting sequences have been demonstrated to be necessary and sufficient for targeting proteins into the plastids of many algal groups, including chlorarachniophytes. Here, we report a new type of targeting signal that is required for delivering a RubisCO small subunit (RbcS) protein into the secondary plastids of chlorarachniophyte algae. In this study, we analyzed the plastid-targeting ability of an RbcS pre-protein, using green fluorescent protein (GFP) as a reporter molecule in chlorarachniophyte cells. We demonstrate that the N-terminal bipartite targeting sequence of the RbcS pre-protein is not sufficient, and that a part of the mature protein is also necessary for plastid targeting. By deletion analyses of amino acids, we determined the approximate location of an internal plastid-targeting signal within the mature protein, which is involved in targeting the protein from the ER into the chlorarachniophyte plastids.
Collapse
Affiliation(s)
- Yoshihisa Hirakawa
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba 305-8572, Japan
| | | |
Collapse
|
40
|
Felsner G, Sommer MS, Maier UG. The physical and functional borders of transit peptide-like sequences in secondary endosymbionts. BMC PLANT BIOLOGY 2010; 10:223. [PMID: 20958984 PMCID: PMC3017844 DOI: 10.1186/1471-2229-10-223] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 10/19/2010] [Indexed: 05/08/2023]
Abstract
BACKGROUND Plastids rely on protein supply by their host cells. In plastids surrounded by two membranes (primary plastids) targeting of these proteins is facilitated by an N-terminal targeting signal, the transit peptide. In secondary plastids (surrounded by three or four membranes), transit peptide-like regions are an essential part of a bipartite topogenic signal sequence (BTS), and generally found adjacent to a N-terminally located signal peptide of the plastid pre-proteins. As in primary plastids, for which no wealth of functional information about transit peptide features exists, the transit peptide-like regions used for import into secondary ones show some common features only, which are also poorly characterized. RESULTS We modified the BTS (in the transit peptide-like region) of the plastid precursor fucoxanthin-chlorophyll a/c binding protein D (FcpD) fused to GFP as model substrate for the characterization of pre-protein import into the secondary plastids of diatoms. Thereby we show that (i) pre-protein import is highly charge dependent. Positive net charge is necessary for transport across the plastid envelope, but not across the periplastid membrane. Acidic net charge perturbs pre-protein import within the ER. Moreover, we show that (ii) the mature domain of the pre-protein can provide intrinsic transit peptide functions. CONCLUSIONS Our results indicate important characteristics of targeting signals of proteins imported into secondary plastids surrounded by four membranes. In addition, we show a self-targeting mechanism, in which the mature protein domain contributes to the transit peptide function. Thus, this phenomenon lowers the demand for pre-sequences evolved during the course of endosymbiosis.
Collapse
Affiliation(s)
- Gregor Felsner
- Laboratory for Cell Biology, Philipps University Marburg, Karl-von-Frisch Str.8, D-35032 Marburg, Germany
| | - Maik S Sommer
- Laboratory for Cell Biology, Philipps University Marburg, Karl-von-Frisch Str.8, D-35032 Marburg, Germany
- Department of Molecular Cell Biology of Plants, Goethe-University of Frankfurt, Max-von-Laue Str. 8, D-60438 Frankfurt, Germany
| | - Uwe G Maier
- Laboratory for Cell Biology, Philipps University Marburg, Karl-von-Frisch Str.8, D-35032 Marburg, Germany
| |
Collapse
|
41
|
Wägele H, Deusch O, Händeler K, Martin R, Schmitt V, Christa G, Pinzger B, Gould SB, Dagan T, Klussmann-Kolb A, Martin W. Transcriptomic evidence that longevity of acquired plastids in the photosynthetic slugs Elysia timida and Plakobranchus ocellatus does not entail lateral transfer of algal nuclear genes. Mol Biol Evol 2010; 28:699-706. [PMID: 20829345 PMCID: PMC3002249 DOI: 10.1093/molbev/msq239] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Sacoglossan sea slugs are unique in the animal kingdom in that they sequester and maintain active plastids that they acquire from the siphonaceous algae upon which they feed, making the animals photosynthetic. Although most sacoglossan species digest their freshly ingested plastids within hours, four species from the family Plakobranchidae retain their stolen plastids (kleptoplasts) in a photosynthetically active state on timescales of weeks to months. The molecular basis of plastid maintenance within the cytosol of digestive gland cells in these photosynthetic metazoans is yet unknown but is widely thought to involve gene transfer from the algal food source to the slugs based upon previous investigations of single genes. Indeed, normal plastid development requires hundreds of nuclear-encoded proteins, with protein turnover in photosystem II in particular known to be rapid under various conditions. Moreover, only algal plastids, not the algal nuclei, are sequestered by the animals during feeding. If algal nuclear genes are transferred to the animal either during feeding or in the germ line, and if they are expressed, then they should be readily detectable with deep-sequencing methods. We have sequenced expressed mRNAs from actively photosynthesizing, starved individuals of two photosynthetic sea slug species, Plakobranchus ocellatus Van Hasselt, 1824 and Elysia timida Risso, 1818. We find that nuclear-encoded, algal-derived genes specific to photosynthetic function are expressed neither in P. ocellatus nor in E. timida. Despite their dramatic plastid longevity, these photosynthetic sacoglossan slugs do not express genes acquired from algal nuclei in order to maintain plastid function.
Collapse
Affiliation(s)
- Heike Wägele
- Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Keeling PJ. The endosymbiotic origin, diversification and fate of plastids. Philos Trans R Soc Lond B Biol Sci 2010; 365:729-48. [PMID: 20124341 DOI: 10.1098/rstb.2009.0103] [Citation(s) in RCA: 373] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Plastids and mitochondria each arose from a single endosymbiotic event and share many similarities in how they were reduced and integrated with their host. However, the subsequent evolution of the two organelles could hardly be more different: mitochondria are a stable fixture of eukaryotic cells that are neither lost nor shuffled between lineages, whereas plastid evolution has been a complex mix of movement, loss and replacement. Molecular data from the past decade have substantially untangled this complex history, and we now know that plastids are derived from a single endosymbiotic event in the ancestor of glaucophytes, red algae and green algae (including plants). The plastids of both red algae and green algae were subsequently transferred to other lineages by secondary endosymbiosis. Green algal plastids were taken up by euglenids and chlorarachniophytes, as well as one small group of dinoflagellates. Red algae appear to have been taken up only once, giving rise to a diverse group called chromalveolates. Additional layers of complexity come from plastid loss, which has happened at least once and probably many times, and replacement. Plastid loss is difficult to prove, and cryptic, non-photosynthetic plastids are being found in many non-photosynthetic lineages. In other cases, photosynthetic lineages are now understood to have evolved from ancestors with a plastid of different origin, so an ancestral plastid has been replaced with a new one. Such replacement has taken place in several dinoflagellates (by tertiary endosymbiosis with other chromalveolates or serial secondary endosymbiosis with a green alga), and apparently also in two rhizarian lineages: chlorarachniophytes and Paulinella (which appear to have evolved from chromalveolate ancestors). The many twists and turns of plastid evolution each represent major evolutionary transitions, and each offers a glimpse into how genomes evolve and how cells integrate through gene transfers and protein trafficking.
Collapse
Affiliation(s)
- Patrick J Keeling
- Botany Department, Canadian Institute for Advanced Research, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4.
| |
Collapse
|
43
|
Abstract
N-terminal signal peptides direct secretory proteins into the ER (endoplasmic reticulum) of eukaryotes or the periplasmic space of prokaryotes. A hydrophobic core (h-region) is important for signal sequence function; however, the mechanism of h-region action is not resolved. To gain new insight into signal sequences, bioinformatic analysis of h-regions from humans, Saccharomyces cerevisiae, Trypanosoma brucei and Escherichia coli was performed. Each species contains a unique set of peptide motifs (h-motifs) characterized by identity components (i.e. sequence of conserved amino acids) joined by spacers. Human h-motifs have four identity components, whereas those from the other species utilize three identity components. Example of h-motifs are human Hs3 {L-x(2)-[AGILPV]-L-x(0,2)-L}, S. cerevisiae Sc1 [L-x(0,2)-S-x(0,3)-A], T. brucei Tb2 {L-x(1,2)-L-[AILV]} and E. coli Ec1 [A-x(0,2)-L-x(0,3)-A]. The physiological relevance of h-motifs was tested with a T. brucei microsomal system for translocation of a VSG (variant surface glycoprotein)-117 signal peptide. Disruption of h-motifs by scrambling of sequences in h-regions produced defective signal peptides, although the hydrophobicity of the peptide was not altered. We conclude that: (i) h-regions harbour h-motifs, and are not random hydrophobic amino acids; (ii) h-regions from different species contain unique sets of h-motifs; and (iii) h-motifs contribute to the biological activity of ER signal peptides. h-Regions are ‘scaffolds’ in which functional h-motifs are embedded. A hypothetical model for h-motif interactions with a Sec61p protein translocon is presented.
Collapse
|
44
|
Hirakawa Y, Gile GH, Ota S, Keeling PJ, Ishida KI. Characterization of periplastidal compartment-targeting signals in chlorarachniophytes. Mol Biol Evol 2010; 27:1538-45. [PMID: 20133351 DOI: 10.1093/molbev/msq038] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Secondary plastids are acquired by the engulfment and retention of eukaryotic algae, which results in an additional surrounding membrane or pair of membranes relative to the more familiar primary plastids of land plants. In most cases, the endocytosed alga loses its eukaryotic genome as it becomes integrated, but in two algal groups, the cryptophytes and chlorarachniophytes, the secondary plastids retain a vestigial nucleus in the periplastidal compartment (PPC), the remnant eukaryotic cytoplasm between the inner and the outer membrane pairs. Many essential housekeeping genes are missing from these reduced genomes, suggesting that they are now encoded in the host nucleus and their products are targeted to the PPC. One such nucleus-encoded, PPC-targeted protein, the translation elongation factor like (EFL) was recently identified in chlorarachniophytes. It bears an N-terminal-targeting sequence comprising a signal peptide and a transit peptide-like sequence (TPL) similar to the plastid-targeted proteins of chlorarachniophytes as well as a hydrophilic C-terminal extension rich in lysine and aspartic acid. Here, we characterize the function of the N- and C-terminal extensions of PPC-targeted EFL in transformed chlorarachniophyte cells. Using green fluorescent protein as a reporter molecule, we demonstrate that several negatively charged amino acids within the TPL are essential for accurate targeting to the PPC. Our findings further reveal that the C-terminal extension functions as a PPC retention signal in combination with an N-terminal plastid-targeting peptide, which suggests that plastid and PPC proteins may be sorted in the PPC.
Collapse
Affiliation(s)
- Yoshihisa Hirakawa
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | | | | | | | | |
Collapse
|
45
|
Bullmann L, Haarmann R, Mirus O, Bredemeier R, Hempel F, Maier UG, Schleiff E. Filling the gap, evolutionarily conserved Omp85 in plastids of chromalveolates. J Biol Chem 2009; 285:6848-56. [PMID: 20042599 DOI: 10.1074/jbc.m109.074807] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chromalveolates are a diverse group of protists that include many ecologically and medically relevant organisms such as diatoms and apicomplexan parasites. They possess plastids generally surrounded by four membranes, which evolved by engulfment of a red alga. Today, most plastid proteins must be imported, but many aspects of protein import into complex plastids are still cryptic. In particular, how proteins cross the third outermost membrane has remained unexplained. We identified a protein in the third outermost membrane of the diatom Phaeodactylum tricornutum with properties comparable to those of the Omp85 family. We demonstrate that the targeting route of P. tricornutum Omp85 parallels that of the translocation channel of the outer envelope membrane of chloroplasts, Toc75. In addition, the electrophysiological properties are similar to those of the Omp85 proteins involved in protein translocation. This supports the hypothesis that P. tricornutum Omp85 is involved in precursor protein translocation, which would close a gap in the fundamental understanding of the evolutionary origin and function of protein import in secondary plastids.
Collapse
Affiliation(s)
- Lars Bullmann
- Cell Biology, Philipps-University Marburg, D-35032 Marburg, Germany
| | | | | | | | | | | | | |
Collapse
|
46
|
On the origin of chloroplasts, import mechanisms of chloroplast-targeted proteins, and loss of photosynthetic ability — review. Folia Microbiol (Praha) 2009; 54:303-21. [DOI: 10.1007/s12223-009-0048-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 03/31/2009] [Indexed: 10/20/2022]
|
47
|
Hirakawa Y, Nagamune K, Ishida KI. Protein targeting into secondary plastids of chlorarachniophytes. Proc Natl Acad Sci U S A 2009; 106:12820-5. [PMID: 19620731 PMCID: PMC2722280 DOI: 10.1073/pnas.0902578106] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Indexed: 01/08/2023] Open
Abstract
Most plastid proteins are encoded by the nuclear genome, and consequently, need to be transported into plastids across multiple envelope membranes. In diverse organisms possessing secondary plastids, nuclear-encoded plastid precursor proteins (preproteins) commonly have an N-terminal extension that consists of an endoplasmic reticulum (ER)-targeting signal peptide and a transit peptide-like sequence (TPL). This bipartite targeting peptide is believed to be necessary for targeting the preproteins into the secondary plastids. Here, we newly demonstrate the function of the bipartite targeting peptides of an algal group, chlorarachniophytes, and characterize the functional domains of the TPL in the precursor of a plastid protein, ATP synthase delta subunit (AtpD), using a GFP as a reporter molecule. We show that the C-terminal portion of the TPL is important for targeting the AtpD preprotein from the ER into the chlorarachniophyte plastids, and several positively charged amino acids in the TPL are also necessary for transporting the preprotein across the 2 innermost plastid membranes. Compared with other groups with secondary plastids, the TPL functional domains of the chlorarachniophytes are unique, which might be caused by independent acquisition of their plastids.
Collapse
Affiliation(s)
- Yoshihisa Hirakawa
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba 305-8572, Japan
| | - Kisaburo Nagamune
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba 305-8572, Japan
| | - Ken-ichiro Ishida
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba 305-8572, Japan
| |
Collapse
|
48
|
An unusual ERAD-like complex is targeted to the apicoplast of Plasmodium falciparum. EUKARYOTIC CELL 2009; 8:1134-45. [PMID: 19502583 DOI: 10.1128/ec.00083-09] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many apicomplexan parasites, including Plasmodium falciparum, harbor a so-called apicoplast, a complex plastid of red algal origin which was gained by a secondary endosymbiotic event. The exact molecular mechanisms directing the transport of nuclear-encoded proteins to the apicoplast of P. falciparum are not well understood. Recently, in silico analyses revealed a second copy of proteins homologous to components of the endoplasmic reticulum (ER)-associated protein degradation (ERAD) system in organisms with secondary plastids, including the malaria parasite P. falciparum. These proteins are predicted to be endowed with an apicoplast targeting signal and are suggested to play a role in the transport of nuclear-encoded proteins to the apicoplast. Here, we have studied components of this ERAD-derived putative preprotein translocon complex in malaria parasites. Using transfection technology coupled with fluorescence imaging techniques we can demonstrate that the N terminus of several ERAD-derived components targets green fluorescent protein to the apicoplast. Furthermore, we confirm that full-length PfsDer1-1 and PfsUba1 (homologues of yeast ERAD components) localize to the apicoplast, where PfsDer1-1 tightly associates with membranes. Conversely, PfhDer1-1 (a host-specific copy of the Der1-1 protein) localizes to the ER. Our data suggest that ERAD components have been "rewired" to provide a conduit for protein transport to the apicoplast. Our results are discussed in relation to the nature of the apicoplast protein transport machinery.
Collapse
|
49
|
Weber T, Gruber A, Kroth PG. The presence and localization of thioredoxins in diatoms, unicellular algae of secondary endosymbiotic origin. MOLECULAR PLANT 2009; 2:468-77. [PMID: 19825630 DOI: 10.1093/mp/ssp010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Diatoms are unicellular algae of great ecological importance. So far, very little is known about the regulation of carbon fixation in these algae; however, there are strong indications that in diatom plastids, the ferredoxin/thioredoxin system might play a minor role in redox regulation of the photosynthetic reactions compared to land plants. Until now, it is unknown whether there are fewer or other target enzymes of thioredoxins in diatoms. Only a single potential target enzyme for thioredoxin, the plastidic fructose-1,6-bisphosphatase, has yet been identified. Nevertheless, during the annotation of the genome of the diatom Phaeodactylum tricornutum, we identified several genes encoding different thioredoxins. Utilizing in vivo expression of GFP:presequence fusion proteins in P. tricornutum, we were able to show that these thioredoxins are targeted either into plastids, mitochondria, or remain in the cytosol. Surprisingly, two of the three usually cytosolic thioredoxin h proteins are apparently plastid associated and, together with a thioredoxin reductase, putatively located in the periplastidic compartment. This is one of the few indications for so far unknown enzymatic reactions in the space between the two pairs of diatom plastid envelope membranes.
Collapse
Affiliation(s)
- Till Weber
- Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany
| | | | | |
Collapse
|
50
|
Hempel F, Bullmann L, Lau J, Zauner S, Maier UG. ERAD-derived preprotein transport across the second outermost plastid membrane of diatoms. Mol Biol Evol 2009; 26:1781-90. [PMID: 19377060 DOI: 10.1093/molbev/msp079] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The diatom Phaeodactylum tricornutum harbors a plastid that is surrounded by four membranes and evolved by way of secondary endosymbiosis. Like land plants, most of its plastid proteins are encoded as preproteins on the nuclear genome of the host cell and are resultantly redirected into the organelle. Because two more membranes are present in diatoms than the one pair surrounding primary plastids, the targeting situation is obviously different and more complex. In this work, we focus on preprotein transport across the second outermost plastid membrane -- an issue that was experimentally inaccessible until now. We provide first indications that our hypothesis of an ERAD (ER-associated degradation)-derived preprotein transport system might be correct. Our data demonstrate that the symbiont-specific Der1 proteins, sDer1-1 and sDer1-2, form an oligomeric complex within the second outermost membrane of the complex plastid. Moreover, we present first evidence that the complex interacts with transit peptides of preproteins being transported across this membrane into the periplastidal compartment but not with transit peptides of stromal-targeted proteins. Thus, the sDer1 complex might have an additional role in discriminating preproteins that are transported across the two outermost membranes from preproteins directed across all four membranes of the complex plastid. Altogether, our studies of the symbiont-specific ERAD-like machinery of diatoms suggest that a preexisting cellular machinery was recycled to fulfill a novel function during the transition of a former free-living eukaryote into a secondary endosymbiont.
Collapse
Affiliation(s)
- Franziska Hempel
- Department of Cell Biology, Philipps-University of Marburg, Marburg, Germany
| | | | | | | | | |
Collapse
|