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Flood D, Lee ES, Taylor CT. Intracellular energy production and distribution in hypoxia. J Biol Chem 2023; 299:105103. [PMID: 37507013 PMCID: PMC10480318 DOI: 10.1016/j.jbc.2023.105103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
The hydrolysis of ATP is the primary source of metabolic energy for eukaryotic cells. Under physiological conditions, cells generally produce more than sufficient levels of ATP to fuel the active biological processes necessary to maintain homeostasis. However, mechanisms underpinning the distribution of ATP to subcellular microenvironments with high local demand remain poorly understood. Intracellular distribution of ATP in normal physiological conditions has been proposed to rely on passive diffusion across concentration gradients generated by ATP producing systems such as the mitochondria and the glycolytic pathway. However, subcellular microenvironments can develop with ATP deficiency due to increases in local ATP consumption. Alternatively, ATP production can be reduced during bioenergetic stress during hypoxia. Mammalian cells therefore need to have the capacity to alter their metabolism and energy distribution strategies to compensate for local ATP deficits while also controlling ATP production. It is highly likely that satisfying the bioenergetic requirements of the cell involves the regulated distribution of ATP producing systems to areas of high ATP demand within the cell. Recently, the distribution (both spatially and temporally) of ATP-producing systems has become an area of intense investigation. Here, we review what is known (and unknown) about intracellular energy production and distribution and explore potential mechanisms through which this targeted distribution can be altered in hypoxia, with the aim of stimulating investigation in this important, yet poorly understood field of research.
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Affiliation(s)
- Darragh Flood
- Conway Institute of Biomolecular and Biomedical Research and School of Medicine, University College Dublin, Dublin, Ireland
| | - Eun Sang Lee
- Conway Institute of Biomolecular and Biomedical Research and School of Medicine, University College Dublin, Dublin, Ireland
| | - Cormac T Taylor
- Conway Institute of Biomolecular and Biomedical Research and School of Medicine, University College Dublin, Dublin, Ireland.
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Bhattacharya D, Etten JV, Benites LF, Stephens TG. Endosymbiotic ratchet accelerates divergence after organelle origin: The Paulinella model for plastid evolution: The Paulinella model for plastid evolution. Bioessays 2023; 45:e2200165. [PMID: 36328783 DOI: 10.1002/bies.202200165] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/16/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022]
Abstract
We hypothesize that as one of the most consequential events in evolution, primary endosymbiosis accelerates lineage divergence, a process we refer to as the endosymbiotic ratchet. Our proposal is supported by recent work on the photosynthetic amoeba, Paulinella, that underwent primary plastid endosymbiosis about 124 Mya. This amoeba model allows us to explore the early impacts of photosynthetic organelle (plastid) origin on the host lineage. The current data point to a central role for effective population size (Ne ) in accelerating divergence post-endosymbiosis due to limits to dispersal and reproductive isolation that reduce Ne , leading to local adaptation. We posit that isolated populations exploit different strategies and behaviors and assort themselves in non-overlapping niches to minimize competition during the early, rapid evolutionary phase of organelle integration. The endosymbiotic ratchet provides a general framework for interpreting post-endosymbiosis lineage evolution that is driven by disruptive selection and demographic and population shifts. Also see the video abstract here: https://youtu.be/gYXrFM6Zz6Q.
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Affiliation(s)
- Debashish Bhattacharya
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Julia Van Etten
- Graduate Program in Ecology and Evolution, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - L Felipe Benites
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Timothy G Stephens
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
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Kareya MS, Mariam I, Shaikh KM, Nesamma AA, Jutur PP. Photosynthetic Carbon Partitioning and Metabolic Regulation in Response to Very-Low and High CO 2 in Microchloropsis gaditana NIES 2587. FRONTIERS IN PLANT SCIENCE 2020; 11:981. [PMID: 32719702 PMCID: PMC7348049 DOI: 10.3389/fpls.2020.00981] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 06/16/2020] [Indexed: 05/06/2023]
Abstract
Photosynthetic organisms fix inorganic carbon through carbon capture machinery (CCM) that regulates the assimilation and accumulation of carbon around ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). However, few constraints that govern the central carbon metabolism are regulated by the carbon capture and partitioning machinery. In order to divert the cellular metabolism toward lipids and/or biorenewables it is important to investigate and understand the molecular mechanisms of the CO2-driven carbon partitioning. In this context, strategies for enhancement of CO2 fixation which will increase the overall biomass and lipid yields, can provide clues on understanding the carbon assimilation pathway, and may lead to new targets for genetic engineering in microalgae. In the present study, we have focused on the physiological and metabolomic response occurring within marine oleaginous microalgae Microchloropsis gaditana NIES 2587, under the influence of very-low CO2 (VLC; 300 ppm, or 0.03%) and high CO2 (HC; 30,000 ppm, or 3% v/v). Our results demonstrate that HC supplementation in M. gaditana channelizes the carbon flux toward the production of long chain polyunsaturated fatty acids (LC-PUFAs) and also increases the overall biomass productivities (up to 2.0 fold). Also, the qualitative metabolomics has identified nearly 31 essential metabolites, among which there is a significant fold change observed in accumulation of sugars and alcohols such as galactose and phytol in VLC as compared to HC. In conclusion, our focus is to understand the entire carbon partitioning and metabolic regulation within these photosynthetic cell factories, which will be further evaluated through multiomics approach for enhanced productivities of biomass, biofuels, and bioproducts (B3).
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Affiliation(s)
| | | | | | | | - Pannaga Pavan Jutur
- Omics of Algae Group, Industrial Biotechnology, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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4
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Dunn CD, Paavilainen VO. Wherever I may roam: organellar protein targeting and evolvability. Curr Opin Genet Dev 2019; 58-59:9-16. [DOI: 10.1016/j.gde.2019.07.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/26/2019] [Accepted: 07/20/2019] [Indexed: 02/08/2023]
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Kennedy F, Martin A, Bowman JP, Wilson R, McMinn A. Dark metabolism: a molecular insight into how the Antarctic sea-ice diatom Fragilariopsis cylindrus survives long-term darkness. THE NEW PHYTOLOGIST 2019; 223:675-691. [PMID: 30985935 PMCID: PMC6617727 DOI: 10.1111/nph.15843] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 04/02/2019] [Indexed: 05/27/2023]
Abstract
Light underneath Antarctic sea-ice is below detectable limits for up to 4 months of the year. The ability of Antarctic sea-ice diatoms to survive this prolonged darkness relies on their metabolic capability. This study is the first to examine the proteome of a prominent sea-ice diatom in response to extended darkness, focusing on the protein-level mechanisms of dark survival. The Antarctic diatom Fragilariopsis cylindrus was grown under continuous light or darkness for 120 d. The whole cell proteome was quantitatively analysed by nano-LC-MS/MS to investigate metabolic changes that occur during sustained darkness and during recovery under illumination. Enzymes of metabolic pathways, particularly those involved in respiratory processes, tricarboxylic acid cycle, glycolysis, the Entner-Doudoroff pathway, the urea cycle and the mitochondrial electron transport chain became more abundant in the dark. Within the plastid, carbon fixation halted while the upper sections of the glycolysis, gluconeogenesis and pentose phosphate pathways became less active. We have discovered how F. cylindrus utilises an ancient alternative metabolic mechanism that enables its capacity for long-term dark survival. By sustaining essential metabolic processes in the dark, F. cylindrus retains the functionality of the photosynthetic apparatus, ensuring rapid recovery upon re-illumination.
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Affiliation(s)
- Fraser Kennedy
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobart7000TasmaniaAustralia
| | - Andrew Martin
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobart7000TasmaniaAustralia
| | - John P. Bowman
- Centre for Food Safety and InnovationTasmanian Institute of AgricultureHobart7000TasmaniaAustralia
| | - Richard Wilson
- Central Science LaboratoryUniversity of TasmaniaHobart7000TasmaniaAustralia
| | - Andrew McMinn
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobart7000TasmaniaAustralia
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6
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Evolutionary Perspectives of Genotype-Phenotype Factors in Leishmania Metabolism. J Mol Evol 2018; 86:443-456. [PMID: 30022295 DOI: 10.1007/s00239-018-9857-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 07/13/2018] [Indexed: 10/28/2022]
Abstract
The sandfly midgut and the human macrophage phagolysosome provide antagonistic metabolic niches for the endoparasite Leishmania to survive and populate. Although these environments fluctuate across developmental stages, the relative changes in both these environments across parasite generations might remain gradual. Such environmental restrictions might endow parasite metabolism with a choice of specific genotypic and phenotypic factors that can constrain enzyme evolution for successful adaptation to the host. With respect to the available cellular information for Leishmania species, for the first time, we measure the relative contribution of eight inter-correlated predictors related to codon usage, GC content, gene expression, gene length, multi-functionality, and flux-coupling potential of an enzyme on the evolutionary rates of singleton metabolic genes and further compare their effects across three Leishmania species. Our analysis reveals that codon adaptation, multi-functionality, and flux-coupling potential of an enzyme are independent contributors of enzyme evolutionary rates, which can together explain a large variation in enzyme evolutionary rates across species. We also hypothesize that a species-specific occurrence of duplicated genes in novel subcellular locations can create new flux routes through certain singleton flux-coupled enzymes, thereby constraining their evolution. A cross-species comparison revealed both common and species-specific genes whose evolutionary divergence was constrained by multiple independent factors. Out of these, previously known pharmacological targets and virulence factors in Leishmania were identified, suggesting their evolutionary reasons for being important survival factors to the parasite. All these results provide a fundamental understanding of the factors underlying adaptive strategies of the parasite, which can be further targeted.
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Kohnhorst CL, Kyoung M, Jeon M, Schmitt DL, Kennedy EL, Ramirez J, Bracey SM, Luu BT, Russell SJ, An S. Identification of a multienzyme complex for glucose metabolism in living cells. J Biol Chem 2017; 292:9191-9203. [PMID: 28424264 DOI: 10.1074/jbc.m117.783050] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/17/2017] [Indexed: 01/05/2023] Open
Abstract
Sequential metabolic enzymes in glucose metabolism have long been hypothesized to form multienzyme complexes that regulate glucose flux in living cells. However, it has been challenging to directly observe these complexes and their functional roles in living systems. In this work, we have used wide-field and confocal fluorescence microscopy to investigate the spatial organization of metabolic enzymes participating in glucose metabolism in human cells. We provide compelling evidence that human liver-type phosphofructokinase 1 (PFKL), which catalyzes a bottleneck step of glycolysis, forms various sizes of cytoplasmic clusters in human cancer cells, independent of protein expression levels and of the choice of fluorescent tags. We also report that these PFKL clusters colocalize with other rate-limiting enzymes in both glycolysis and gluconeogenesis, supporting the formation of multienzyme complexes. Subsequent biophysical characterizations with fluorescence recovery after photobleaching and FRET corroborate the formation of multienzyme metabolic complexes in living cells, which appears to be controlled by post-translational acetylation on PFKL. Importantly, quantitative high-content imaging assays indicated that the direction of glucose flux between glycolysis, the pentose phosphate pathway, and serine biosynthesis seems to be spatially regulated by the multienzyme complexes in a cluster-size-dependent manner. Collectively, our results reveal a functionally relevant, multienzyme metabolic complex for glucose metabolism in living human cells.
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Affiliation(s)
- Casey L Kohnhorst
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Minjoung Kyoung
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Miji Jeon
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Danielle L Schmitt
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Erin L Kennedy
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Julio Ramirez
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Syrena M Bracey
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Bao Tran Luu
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Sarah J Russell
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - Songon An
- From the Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, Maryland 21250
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8
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Garibay-Hernández A, Barkla BJ, Vera-Estrella R, Martinez A, Pantoja O. Membrane Proteomic Insights into the Physiology and Taxonomy of an Oleaginous Green Microalga. PLANT PHYSIOLOGY 2017; 173:390-416. [PMID: 27837088 PMCID: PMC5210721 DOI: 10.1104/pp.16.01240] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/03/2016] [Indexed: 05/22/2023]
Abstract
Ettlia oleoabundans is a nonsequenced oleaginous green microalga. Despite the significant biotechnological interest in producing value-added compounds from the acyl lipids of this microalga, a basic understanding of the physiology and biochemistry of oleaginous microalgae is lacking, especially under nitrogen deprivation conditions known to trigger lipid accumulation. Using an RNA sequencing-based proteomics approach together with manual annotation, we are able to provide, to our knowledge, the first membrane proteome of an oleaginous microalga. This approach allowed the identification of novel proteins in E. oleoabundans, including two photoprotection-related proteins, Photosystem II Subunit S and Maintenance of Photosystem II under High Light1, which were considered exclusive to higher photosynthetic organisms, as well as Retinitis Pigmentosa Type 2-Clathrin Light Chain, a membrane protein with a novel domain architecture. Free-flow zonal electrophoresis of microalgal membranes coupled to liquid chromatography-tandem mass spectrometry proved to be a useful technique for determining the intracellular location of proteins of interest. Carbon-flow compartmentalization in E. oleoabundans was modeled using this information. Molecular phylogenetic analyses of protein markers and 18S ribosomal DNA support the reclassification of E. oleoabundans within the trebouxiophycean microalgae, rather than with the Chlorophyceae class, in which it is currently classified, indicating that it may not be closely related to the model green alga Chlamydomonas reinhardtii A detailed survey of biological processes taking place in the membranes of nitrogen-deprived E. oleoabundans, including lipid metabolism, provides insights into the basic biology of this nonmodel organism.
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Affiliation(s)
- Adriana Garibay-Hernández
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210 Mexico (A.G.-H., R.V.-E., A.M., O.P.); and
- Southern Cross Plant Science, Southern Cross University, Lismore, 2480 New South Wales, Australia (B.J.B.)
| | - Bronwyn J Barkla
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210 Mexico (A.G.-H., R.V.-E., A.M., O.P.); and
- Southern Cross Plant Science, Southern Cross University, Lismore, 2480 New South Wales, Australia (B.J.B.)
| | - Rosario Vera-Estrella
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210 Mexico (A.G.-H., R.V.-E., A.M., O.P.); and
- Southern Cross Plant Science, Southern Cross University, Lismore, 2480 New South Wales, Australia (B.J.B.)
| | - Alfredo Martinez
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210 Mexico (A.G.-H., R.V.-E., A.M., O.P.); and
- Southern Cross Plant Science, Southern Cross University, Lismore, 2480 New South Wales, Australia (B.J.B.)
| | - Omar Pantoja
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210 Mexico (A.G.-H., R.V.-E., A.M., O.P.); and
- Southern Cross Plant Science, Southern Cross University, Lismore, 2480 New South Wales, Australia (B.J.B.)
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Smith SR, Gillard JTF, Kustka AB, McCrow JP, Badger JH, Zheng H, New AM, Dupont CL, Obata T, Fernie AR, Allen AE. Transcriptional Orchestration of the Global Cellular Response of a Model Pennate Diatom to Diel Light Cycling under Iron Limitation. PLoS Genet 2016; 12:e1006490. [PMID: 27973599 PMCID: PMC5156380 DOI: 10.1371/journal.pgen.1006490] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/16/2016] [Indexed: 11/23/2022] Open
Abstract
Environmental fluctuations affect distribution, growth and abundance of diatoms in nature, with iron (Fe) availability playing a central role. Studies on the response of diatoms to low Fe have either utilized continuous (24 hr) illumination or sampled a single time of day, missing any temporal dynamics. We profiled the physiology, metabolite composition, and global transcripts of the pennate diatom Phaeodactylum tricornutum during steady-state growth at low, intermediate, and high levels of dissolved Fe over light:dark cycles, to better understand fundamental aspects of genetic control of physiological acclimation to growth under Fe-limitation. We greatly expand the catalog of genes involved in the low Fe response, highlighting the importance of intracellular trafficking in Fe-limited diatoms. P. tricornutum exhibited transcriptomic hallmarks of slowed growth leading to prolonged periods of cell division/silica deposition, which could impact biogeochemical carbon sequestration in Fe-limited regions. Light harvesting and ribosome biogenesis transcripts were generally reduced under low Fe while transcript levels for genes putatively involved in the acquisition and recycling of Fe were increased. We also noted shifts in expression towards increased synthesis and catabolism of branched chain amino acids in P. tricornutum grown at low Fe whereas expression of genes involved in central core metabolism were relatively unaffected, indicating that essential cellular function is protected. Beyond the response of P. tricornutum to low Fe, we observed major coordinated shifts in transcript control of primary and intermediate metabolism over light:dark cycles which contribute to a new view of the significance of distinctive diatom pathways, such as mitochondrial glycolysis and the ornithine-urea cycle. This study provides new insight into transcriptional modulation of diatom physiology and metabolism across light:dark cycles in response to Fe availability, providing mechanistic understanding for the ability of diatoms to remain metabolically poised to respond quickly to Fe input and revealing strategies underlying their ecological success. Oceanic diatoms live in constantly fluctuating environments to which they must adapt in order to survive. During sunlit hours, photosynthesis occurs allowing diatoms to store energy used at night to sustain energy demands. Cellular and molecular mechanisms for regulation of phytoplankton growth are important to understand because of their environmental roles at the base of food webs and in regulating carbon flux out of the atmosphere. In ocean ecosystems, the availability of iron (Fe) commonly limits phytoplankton growth and diatoms typically outcompete other phytoplankton when Fe is added, indicating they have adaptations allowing them to both survive at low Fe and rapidly respond to Fe additions. These adaptations may be unique depending on isolation from coastal or oceanic locations. To identify adaptive strategies, we characterized the response of a model diatom, Phaeodactylum tricornutum, to limiting Fe conditions over day:night cycles using a combination of gene expression analyses, metabolite, and physiology measurements. Major coordinated shifts in metabolism and growth were documented over diel cycles, with peak expression of low Fe expressed genes in the dark phase. Diatoms respond to limiting Fe by increasing Fe acquisition, while decreasing growth rate through slowed cell cycle progression, reduced energy acquisition, and subtle metabolic remodeling.
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Affiliation(s)
- Sarah R. Smith
- Integrative Oceanography Division, Scripps Institution of Oceanography, UC San Diego, La Jolla, California, United States of America
- J. Craig Venter Institute, La Jolla, California, United States of America
| | - Jeroen T. F. Gillard
- J. Craig Venter Institute, La Jolla, California, United States of America
- Department of Biology, CSU Bakersfield, Bakersfield, California, United States of America
| | - Adam B. Kustka
- Department of Earth and Environmental Sciences, Rutgers University, Newark, New Jersey, United States of America
| | - John P. McCrow
- J. Craig Venter Institute, La Jolla, California, United States of America
| | - Jonathan H. Badger
- J. Craig Venter Institute, La Jolla, California, United States of America
| | - Hong Zheng
- J. Craig Venter Institute, La Jolla, California, United States of America
| | - Ashley M. New
- Department of Earth and Environmental Sciences, Rutgers University, Newark, New Jersey, United States of America
| | - Chris L. Dupont
- J. Craig Venter Institute, La Jolla, California, United States of America
| | - Toshihiro Obata
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam, Germany
| | - Alisdair R. Fernie
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam, Germany
| | - Andrew E. Allen
- Integrative Oceanography Division, Scripps Institution of Oceanography, UC San Diego, La Jolla, California, United States of America
- J. Craig Venter Institute, La Jolla, California, United States of America
- * E-mail: ,
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Mani S, Thattai M. Wine glasses and hourglasses: Non-adaptive complexity of vesicle traffic in microbial eukaryotes. Mol Biochem Parasitol 2016; 209:58-63. [PMID: 27012485 PMCID: PMC5154330 DOI: 10.1016/j.molbiopara.2016.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Revised: 03/17/2016] [Accepted: 03/18/2016] [Indexed: 12/27/2022]
Abstract
We are motivated by the diversity of vesicle traffic systems in microbial parasites. We present a mathematical model of vesicle traffic in a manner accessible to a broad audience. We show that many complex features of vesicle traffic systems arise spontaneously due to molecular interactions. Traffic features such as compartmental maturation might arise non-adaptively and later be selected for function.
Microbial eukaryotes present a stunning diversity of endomembrane organization. From specialized secretory organelles such as the rhoptries and micronemes of apicomplexans, to peroxisome-derived metabolic compartments such as the glycosomes of kinetoplastids, different microbial taxa have explored different solutions to the compartmentalization and processing of cargo. The basic secretory and endocytic system, comprising the ER, Golgi, endosomes, and plasma membrane, as well as diverse taxon-specific specialized endomembrane organelles, are coupled by a complex network of cargo transport via vesicle traffic. It is tempting to connect form to function, ascribing biochemical roles to each compartment and vesicle of such a system. Here we argue that traffic systems of high complexity could arise through non-adaptive mechanisms via purely physical constraints, and subsequently be exapted for various taxon-specific functions. Our argument is based on a Boolean mathematical model of vesicle traffic: we specify rules of how compartments exchange vesicles; these rules then generate hypothetical cells with different types of endomembrane organization. Though one could imagine a large number of hypothetical vesicle traffic systems, very few of these are consistent with molecular interactions. Such molecular constraints are the bottleneck of a metaphorical hourglass, and the rules that make it through the bottleneck are expected to generate cells with many special properties. Sampling at random from among such rules represents an evolutionary null hypothesis: any properties of the resulting cells must be non-adaptive. We show by example that vesicle traffic systems generated in this random manner are reminiscent of the complex trafficking apparatus of real cells.
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Affiliation(s)
- Somya Mani
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, UAS-GKVK Campus, Bellary Road, Bangalore 560065, India
| | - Mukund Thattai
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, UAS-GKVK Campus, Bellary Road, Bangalore 560065, India.
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11
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Kim J, Fabris M, Baart G, Kim MK, Goossens A, Vyverman W, Falkowski PG, Lun DS. Flux balance analysis of primary metabolism in the diatom Phaeodactylum tricornutum. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 85:161-176. [PMID: 26590126 DOI: 10.1111/tpj.13081] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 06/05/2023]
Abstract
Diatoms (Bacillarophyceae) are photosynthetic unicellular microalgae that have risen to ecological prominence in oceans over the past 30 million years. They are of interest as potential feedstocks for sustainable biofuels. Maximizing production of these feedstocks will require genetic modifications and an understanding of algal metabolism. These processes may benefit from genome-scale models, which predict intracellular fluxes and theoretical yields, as well as the viability of knockout and knock-in transformants. Here we present a genome-scale metabolic model of a fully sequenced and transformable diatom: Phaeodactylum tricornutum. The metabolic network was constructed using the P. tricornutum genome, biochemical literature, and online bioinformatic databases. Intracellular fluxes in P. tricornutum were calculated for autotrophic, mixotrophic and heterotrophic growth conditions, as well as knockout conditions that explore the in silico role of glycolytic enzymes in the mitochondrion. The flux distribution for lower glycolysis in the mitochondrion depended on which transporters for TCA cycle metabolites were included in the model. The growth rate predictions were validated against experimental data obtained using chemostats. Two published studies on this organism were used to validate model predictions for cyclic electron flow under autotrophic conditions, and fluxes through the phosphoketolase, glycine and serine synthesis pathways under mixotrophic conditions. Several gaps in annotation were also identified. The model also explored unusual features of diatom metabolism, such as the presence of lower glycolysis pathways in the mitochondrion, as well as differences between P. tricornutum and other photosynthetic organisms.
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Affiliation(s)
- Joomi Kim
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Michele Fabris
- Plant Functional Biology and Climate Change Cluster (C3), Faculty of Science University of Technology, Sydney, New South Wales, Australia
- Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, B-9052, Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Gent, Belgium
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, B-9000, Gent, Belgium
| | - Gino Baart
- Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, B-9052, Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Gent, Belgium
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, B-9000, Gent, Belgium
- Centre of Microbial and Plant Genetics Lab for Genetics and Genomics and Leuven Institute for Beer Research, Leuven University, Gaston Geenslaan 1, B-3001, Leuven, Belgium
| | - Min K Kim
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers University, Camden, NJ, 08102, USA
| | - Alain Goossens
- Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, B-9052, Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Gent, Belgium
| | - Wim Vyverman
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, B-9000, Gent, Belgium
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Desmond S Lun
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers University, Camden, NJ, 08102, USA
- Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ, 08901, USA
- School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, South Australia, Australia
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Haanstra JR, González-Marcano EB, Gualdrón-López M, Michels PAM. Biogenesis, maintenance and dynamics of glycosomes in trypanosomatid parasites. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:1038-48. [PMID: 26384872 DOI: 10.1016/j.bbamcr.2015.09.015] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 12/31/2022]
Abstract
Peroxisomes of organisms belonging to the protist group Kinetoplastea, which include trypanosomatid parasites of the genera Trypanosoma and Leishmania, are unique in playing a crucial role in glycolysis and other parts of intermediary metabolism. They sequester the majority of the glycolytic enzymes and hence are called glycosomes. Their glycosomal enzyme content can vary strongly, particularly quantitatively, between different trypanosomatid species, and within each species during its life cycle. Turnover of glycosomes by autophagy of redundant ones and biogenesis of a new population of organelles play a pivotal role in the efficient adaptation of the glycosomal metabolic repertoire to the sudden, major nutritional changes encountered during the transitions in their life cycle. The overall mechanism of glycosome biogenesis is similar to that of peroxisomes in other organisms, but the homologous peroxins involved display low sequence conservation as well as variations in motifs mediating crucial protein-protein interactions in the process. The correct compartmentalisation of enzymes is essential for the regulation of the trypanosomatids' metabolism and consequently for their viability. For Trypanosoma brucei it was shown that glycosomes also play a crucial role in its life-cycle regulation: a crucial developmental control switch involves the translocation of a protein phosphatase from the cytosol into the organelles. Many glycosomal proteins are differentially phosphorylated in different life-cycle stages, possibly indicative of regulation of enzyme activities as an additional means to adapt the metabolic network to the different environmental conditions encountered.
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Affiliation(s)
- Jurgen R Haanstra
- Systems Bioinformatics, Vrije Universiteit Amsterdam, The Netherlands
| | - Eglys B González-Marcano
- Laboratorio de Enzimología de Parásitos, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela
| | - Melisa Gualdrón-López
- Federal University of Minas Gerais, Laboratory of Immunoregulation of Infectious Diseases, Department of Biochemistry and Immunology, Institute for Biological Sciences, Belo Horizonte, Brazil
| | - Paul A M Michels
- Laboratorio de Enzimología de Parásitos, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela; Centre for Translational and Chemical Biology, Institute of Structural and Molecular Biology, School of Biological Sciences, University of Edinburgh, United Kingdom.
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13
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Singh B, Sharma RA. Plant terpenes: defense responses, phylogenetic analysis, regulation and clinical applications. 3 Biotech 2015; 5:129-151. [PMID: 28324581 PMCID: PMC4362742 DOI: 10.1007/s13205-014-0220-2] [Citation(s) in RCA: 197] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 04/10/2014] [Indexed: 12/11/2022] Open
Abstract
The terpenoids constitute the largest class of natural products and many interesting products are extensively applied in the industrial sector as flavors, fragrances, spices and are also used in perfumery and cosmetics. Many terpenoids have biological activities and also used for medical purposes. In higher plants, the conventional acetate-mevalonic acid pathway operates mainly in the cytosol and mitochondria and synthesizes sterols, sesquiterpenes and ubiquinones mainly. In the plastid, the non-mevalonic acid pathway takes place and synthesizes hemi-, mono-, sesqui-, and diterpenes along with carotenoids and phytol tail of chlorophyll. In this review paper, recent developments in the biosynthesis of terpenoids, indepth description of terpene synthases and their phylogenetic analysis, regulation of terpene biosynthesis as well as updates of terpenes which have entered in the clinical studies are reviewed thoroughly.
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Affiliation(s)
- Bharat Singh
- AIB, Amity University Rajasthan, NH-11C, Kant Kalwar, Jaipur, 303 002, India.
| | - Ram A Sharma
- Department of Botany, University of Rajasthan, Jaipur, 302 055, India
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14
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Pattanaik B, Lindberg P. Terpenoids and their biosynthesis in cyanobacteria. Life (Basel) 2015; 5:269-93. [PMID: 25615610 PMCID: PMC4390852 DOI: 10.3390/life5010269] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 01/14/2015] [Indexed: 12/21/2022] Open
Abstract
Terpenoids, or isoprenoids, are a family of compounds with great structural diversity which are essential for all living organisms. In cyanobacteria, they are synthesized from the methylerythritol-phosphate (MEP) pathway, using glyceraldehyde 3-phosphate and pyruvate produced by photosynthesis as substrates. The products of the MEP pathway are the isomeric five-carbon compounds isopentenyl diphosphate and dimethylallyl diphosphate, which in turn form the basic building blocks for formation of all terpenoids. Many terpenoid compounds have useful properties and are of interest in the fields of pharmaceuticals and nutrition, and even potentially as future biofuels. The MEP pathway, its function and regulation, and the subsequent formation of terpenoids have not been fully elucidated in cyanobacteria, despite its relevance for biotechnological applications. In this review, we summarize the present knowledge about cyanobacterial terpenoid biosynthesis, both regarding the native metabolism and regarding metabolic engineering of cyanobacteria for heterologous production of non-native terpenoids.
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Affiliation(s)
- Bagmi Pattanaik
- Department of Chemistry-Ångström, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden.
| | - Pia Lindberg
- Department of Chemistry-Ångström, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden.
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15
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Brown RWB, Collingridge PW, Gull K, Rigden DJ, Ginger ML. Evidence for loss of a partial flagellar glycolytic pathway during trypanosomatid evolution. PLoS One 2014; 9:e103026. [PMID: 25050549 PMCID: PMC4106842 DOI: 10.1371/journal.pone.0103026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/27/2014] [Indexed: 11/18/2022] Open
Abstract
Classically viewed as a cytosolic pathway, glycolysis is increasingly recognized as a metabolic pathway exhibiting surprisingly wide-ranging variations in compartmentalization within eukaryotic cells. Trypanosomatid parasites provide an extreme view of glycolytic enzyme compartmentalization as several glycolytic enzymes are found exclusively in peroxisomes. Here, we characterize Trypanosoma brucei flagellar proteins resembling glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoglycerate kinase (PGK): we show the latter associates with the axoneme and the former is a novel paraflagellar rod component. The paraflagellar rod is an essential extra-axonemal structure in trypanosomes and related protists, providing a platform into which metabolic activities can be built. Yet, bioinformatics interrogation and structural modelling indicate neither the trypanosome PGK-like nor the GAPDH-like protein is catalytically active. Orthologs are present in a free-living ancestor of the trypanosomatids, Bodo saltans: the PGK-like protein from B. saltans also lacks key catalytic residues, but its GAPDH-like protein is predicted to be catalytically competent. We discuss the likelihood that the trypanosome GAPDH-like and PGK-like proteins constitute molecular evidence for evolutionary loss of a flagellar glycolytic pathway, either as a consequence of niche adaptation or the re-localization of glycolytic enzymes to peroxisomes and the extensive changes to glycolytic flux regulation that accompanied this re-localization. Evidence indicating loss of localized ATP provision via glycolytic enzymes therefore provides a novel contribution to an emerging theme of hidden diversity with respect to compartmentalization of the ubiquitous glycolytic pathway in eukaryotes. A possibility that trypanosome GAPDH-like protein additionally represents a degenerate example of a moonlighting protein is also discussed.
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Affiliation(s)
- Robert W. B. Brown
- Faculty of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | | | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Daniel J. Rigden
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Michael L. Ginger
- Faculty of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
- * E-mail:
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16
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Crystal structures of SCP2-thiolases of Trypanosomatidae, human pathogens causing widespread tropical diseases: the importance for catalysis of the cysteine of the unique HDCF loop. Biochem J 2013; 455:119-30. [PMID: 23909465 DOI: 10.1042/bj20130669] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Thiolases are essential CoA-dependent enzymes in lipid metabolism. In the present study we report the crystal structures of trypanosomal and leishmanial SCP2 (sterol carrier protein, type-2)-thiolases. Trypanosomatidae cause various widespread devastating (sub)-tropical diseases, for which adequate treatment is lacking. The structures reveal the unique geometry of the active site of this poorly characterized subfamily of thiolases. The key catalytic residues of the classical thiolases are two cysteine residues, functioning as a nucleophile and an acid/base respectively. The latter cysteine residue is part of a CxG motif. Interestingly, this cysteine residue is not conserved in SCP2-thiolases. The structural comparisons now show that in SCP2-thiolases the catalytic acid/base is provided by the cysteine residue of the HDCF motif, which is unique for this thiolase subfamily. This HDCF cysteine residue is spatially equivalent to the CxG cysteine residue of classical thiolases. The HDCF cysteine residue is activated for acid/base catalysis by two main chain NH-atoms, instead of two water molecules, as present in the CxG active site. The structural results have been complemented with enzyme activity data, confirming the importance of the HDCF cysteine residue for catalysis. The data obtained suggest that these trypanosomatid SCP2-thiolases are biosynthetic thiolases. These findings provide promise for drug discovery as biosynthetic thiolases catalyse the first step of the sterol biosynthesis pathway that is essential in several of these parasites.
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17
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Yang JS, Kim J, Park S, Jeon J, Shin YE, Kim S. Spatial and functional organization of mitochondrial protein network. Sci Rep 2013; 3:1403. [PMID: 23466738 PMCID: PMC3590558 DOI: 10.1038/srep01403] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 02/21/2013] [Indexed: 12/24/2022] Open
Abstract
Characterizing the spatial organization of the human mitochondrial proteome will enhance our understanding of mitochondrial functions at the molecular level and provide key insight into protein-disease associations. However, the sub-organellar location and possible association with mitochondrial diseases are not annotated for most mitochondrial proteins. Here, we characterized the functional and spatial organization of mitochondrial proteins by assessing their position in the Mitochondrial Protein Functional (MPF) network. Network position was assigned to the MPF network and facilitated the determination of sub-organellar location and functional organization of mitochondrial proteins. Moreover, network position successfully identified candidate disease genes of several mitochondrial disorders. Thus, our data support the use of network position as a novel method to explore the molecular function and pathogenesis of mitochondrial proteins.
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Affiliation(s)
- Jae-Seong Yang
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongbuk, Korea, 790-784
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18
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Spatial reorganization of Saccharomyces cerevisiae enolase to alter carbon metabolism under hypoxia. EUKARYOTIC CELL 2013; 12:1106-19. [PMID: 23748432 DOI: 10.1128/ec.00093-13] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Hypoxia has critical effects on the physiology of organisms. In the yeast Saccharomyces cerevisiae, glycolytic enzymes, including enolase (Eno2p), formed cellular foci under hypoxia. Here, we investigated the regulation and biological functions of these foci. Focus formation by Eno2p was inhibited temperature independently by the addition of cycloheximide or rapamycin or by the single substitution of alanine for the Val22 residue. Using mitochondrial inhibitors and an antioxidant, mitochondrial reactive oxygen species (ROS) production was shown to participate in focus formation. Focus formation was also inhibited temperature dependently by an SNF1 knockout mutation. Interestingly, the foci were observed in the cell even after reoxygenation. The metabolic turnover analysis revealed that [U-(13)C]glucose conversion to pyruvate and oxaloacetate was accelerated in focus-forming cells. These results suggest that under hypoxia, S. cerevisiae cells sense mitochondrial ROS and, by the involvement of SNF1/AMPK, spatially reorganize metabolic enzymes in the cytosol via de novo protein synthesis, which subsequently increases carbon metabolism. The mechanism may be important for yeast cells under hypoxia, to quickly provide both energy and substrates for the biosynthesis of lipids and proteins independently of the tricarboxylic acid (TCA) cycle and also to fit changing environments.
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19
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Hildebrand M, Abbriano RM, Polle JEW, Traller JC, Trentacoste EM, Smith SR, Davis AK. Metabolic and cellular organization in evolutionarily diverse microalgae as related to biofuels production. Curr Opin Chem Biol 2013; 17:506-14. [PMID: 23538202 DOI: 10.1016/j.cbpa.2013.02.027] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 02/18/2013] [Accepted: 02/26/2013] [Indexed: 12/18/2022]
Abstract
Microalgae are among the most diverse organisms on the planet, and as a result of symbioses and evolutionary selection, the configuration of core metabolic networks is highly varied across distinct algal classes. The differences in photosynthesis, carbon fixation and processing, carbon storage, and the compartmentation of cellular and metabolic processes are substantial and likely to transcend into the efficiency of various steps involved in biofuel molecule production. By highlighting these differences, we hope to provide a framework for comparative analyses to determine the efficiency of the different arrangements or processes. This sets the stage for optimization on the based on information derived from evolutionary selection to diverse algal classes and to synthetic systems.
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Affiliation(s)
- Mark Hildebrand
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA.
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20
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Nakayama T, Ishida KI, Archibald JM. Broad distribution of TPI-GAPDH fusion proteins among eukaryotes: evidence for glycolytic reactions in the mitochondrion? PLoS One 2012; 7:e52340. [PMID: 23284996 PMCID: PMC3527533 DOI: 10.1371/journal.pone.0052340] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 11/14/2012] [Indexed: 12/25/2022] Open
Abstract
Glycolysis is a central metabolic pathway in eukaryotic and prokaryotic cells. In eukaryotes, the textbook view is that glycolysis occurs in the cytosol. However, fusion proteins comprised of two glycolytic enzymes, triosephosphate isomerase (TPI) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were found in members of the stramenopiles (diatoms and oomycetes) and shown to possess amino-terminal mitochondrial targeting signals. Here we show that mitochondrial TPI-GAPDH fusion protein genes are widely spread across the known diversity of stramenopiles, including non-photosynthetic species (Bicosoeca sp. and Blastocystis hominis). We also show that TPI-GAPDH fusion genes exist in three cercozoan taxa (Paulinella chromatophora, Thaumatomastix sp. and Mataza hastifera) and an apusozoan protist, Thecamonas trahens. Interestingly, subcellular localization predictions for other glycolytic enzymes in stramenopiles and a cercozoan show that a significant fraction of the glycolytic enzymes in these species have mitochondrial-targeted isoforms. These results suggest that part of the glycolytic pathway occurs inside mitochondria in these organisms, broadening our knowledge of the diversity of mitochondrial metabolism of protists.
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Affiliation(s)
- Takuro Nakayama
- Department of Biochemistry & Molecular Biology, Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ken-ichiro Ishida
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - John M. Archibald
- Department of Biochemistry & Molecular Biology, Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail:
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21
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Reyes-Prieto A, Moustafa A. Plastid-localized amino acid biosynthetic pathways of Plantae are predominantly composed of non-cyanobacterial enzymes. Sci Rep 2012; 2:955. [PMID: 23233874 PMCID: PMC3518814 DOI: 10.1038/srep00955] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 11/27/2012] [Indexed: 12/15/2022] Open
Abstract
Studies of photosynthetic eukaryotes have revealed that the evolution of plastids from cyanobacteria involved the recruitment of non-cyanobacterial proteins. Our phylogenetic survey of >100 Arabidopsis nuclear-encoded plastid enzymes involved in amino acid biosynthesis identified only 21 unambiguous cyanobacterial-derived proteins. Some of the several non-cyanobacterial plastid enzymes have a shared phylogenetic origin in the three Plantae lineages. We hypothesize that during the evolution of plastids some enzymes encoded in the host nuclear genome were mistargeted into the plastid. Then, the activity of those foreign enzymes was sustained by both the plastid metabolites and interactions with the native cyanobacterial enzymes. Some of the novel enzymatic activities were favored by selective compartmentation of additional complementary enzymes. The mosaic phylogenetic composition of the plastid amino acid biosynthetic pathways and the reduced number of plastid-encoded proteins of non-cyanobacterial origin suggest that enzyme recruitment underlies the recompartmentation of metabolic routes during the evolution of plastids.
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Affiliation(s)
- Adrian Reyes-Prieto
- Canadian Institute for Advanced Research and Department of Biology, University of New Brunswick, Fredericton, Canada.
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22
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Qattan AT, Radulovic M, Crawford M, Godovac-Zimmermann J. Spatial distribution of cellular function: the partitioning of proteins between mitochondria and the nucleus in MCF7 breast cancer cells. J Proteome Res 2012; 11:6080-101. [PMID: 23051583 PMCID: PMC4261608 DOI: 10.1021/pr300736v] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Concurrent proteomics analysis of the nuclei and mitochondria of MCF7 breast cancer cells identified 985 proteins (40% of all detected proteins) present in both organelles. Numerous proteins from all five complexes involved in oxidative phosphorylation (e.g., NDUFA5, NDUFB10, NDUFS1, NDUF2, SDHA, UQRB, UQRC2, UQCRH, COX5A, COX5B, MT-CO2, ATP5A1, ATP5B, ATP5H, etc.), from the TCA-cycle (DLST, IDH2, IDH3A, OGDH, SUCLAG2, etc.), and from glycolysis (ALDOA, ENO1, FBP1, GPI, PGK1, TALDO1, etc.) were distributed to both the nucleus and mitochondria. In contrast, proteins involved in nuclear/mitochondrial RNA processing/translation and Ras/Rab signaling showed different partitioning patterns. The identity of the OxPhos, TCA-cycle, and glycolysis proteins distributed to both the nucleus and mitochondria provides evidence for spatio-functional integration of these processes over the two different subcellular organelles. We suggest that there are unrecognized aspects of functional coordination between the nucleus and mitochondria, that integration of core functional processes via wide subcellular distribution of constituent proteins is a common characteristic of cells, and that subcellular spatial integration of function may be a vital aspect of cancer.
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Affiliation(s)
- Amal T. Qattan
- Proteomics and Molecular Cell Dynamics, Division of Medicine, School of Life and Medical Sciences, University College London, Royal Free Campus, Rowland Hill Street NW3 2PF, United Kingdom
| | - Marko Radulovic
- Proteomics and Molecular Cell Dynamics, Division of Medicine, School of Life and Medical Sciences, University College London, Royal Free Campus, Rowland Hill Street NW3 2PF, United Kingdom
| | - Mark Crawford
- Proteomics and Molecular Cell Dynamics, Division of Medicine, School of Life and Medical Sciences, University College London, Royal Free Campus, Rowland Hill Street NW3 2PF, United Kingdom
| | - Jasminka Godovac-Zimmermann
- Proteomics and Molecular Cell Dynamics, Division of Medicine, School of Life and Medical Sciences, University College London, Royal Free Campus, Rowland Hill Street NW3 2PF, United Kingdom
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23
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Taylor AR, Brownlee C, Wheeler GL. Proton channels in algae: reasons to be excited. TRENDS IN PLANT SCIENCE 2012; 17:675-84. [PMID: 22819465 DOI: 10.1016/j.tplants.2012.06.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Revised: 06/14/2012] [Accepted: 06/18/2012] [Indexed: 05/08/2023]
Abstract
A fundamental requirement of all eukaryotes is the ability to translocate protons across membranes. This is critical in bioenergetics, for compartmentalized metabolism, and to regulate intracellular pH (pH(i)) within a range that is compatible with cellular metabolism. Plants, animals, and algae utilize specialized transport machinery for membrane energization and pH homeostasis that reflects the prevailing ionic conditions in which they evolved. The recent characterization of H(+)-permeable channels in marine and freshwater algae has led to the discovery of novel functions for these transport proteins in both cellular pH homeostasis and sensory biology. Here we review the potential implications for understanding the origins and evolution of membrane excitability and the phytoplankton-based marine ecosystem responses to ocean acidification.
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Affiliation(s)
- Alison R Taylor
- Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28409, USA.
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24
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Müller M, Mentel M, van Hellemond JJ, Henze K, Woehle C, Gould SB, Yu RY, van der Giezen M, Tielens AGM, Martin WF. Biochemistry and evolution of anaerobic energy metabolism in eukaryotes. Microbiol Mol Biol Rev 2012; 76:444-95. [PMID: 22688819 PMCID: PMC3372258 DOI: 10.1128/mmbr.05024-11] [Citation(s) in RCA: 498] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Major insights into the phylogenetic distribution, biochemistry, and evolutionary significance of organelles involved in ATP synthesis (energy metabolism) in eukaryotes that thrive in anaerobic environments for all or part of their life cycles have accrued in recent years. All known eukaryotic groups possess an organelle of mitochondrial origin, mapping the origin of mitochondria to the eukaryotic common ancestor, and genome sequence data are rapidly accumulating for eukaryotes that possess anaerobic mitochondria, hydrogenosomes, or mitosomes. Here we review the available biochemical data on the enzymes and pathways that eukaryotes use in anaerobic energy metabolism and summarize the metabolic end products that they generate in their anaerobic habitats, focusing on the biochemical roles that their mitochondria play in anaerobic ATP synthesis. We present metabolic maps of compartmentalized energy metabolism for 16 well-studied species. There are currently no enzymes of core anaerobic energy metabolism that are specific to any of the six eukaryotic supergroup lineages; genes present in one supergroup are also found in at least one other supergroup. The gene distribution across lineages thus reflects the presence of anaerobic energy metabolism in the eukaryote common ancestor and differential loss during the specialization of some lineages to oxic niches, just as oxphos capabilities have been differentially lost in specialization to anoxic niches and the parasitic life-style. Some facultative anaerobes have retained both aerobic and anaerobic pathways. Diversified eukaryotic lineages have retained the same enzymes of anaerobic ATP synthesis, in line with geochemical data indicating low environmental oxygen levels while eukaryotes arose and diversified.
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Affiliation(s)
| | - Marek Mentel
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Jaap J. van Hellemond
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Katrin Henze
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
| | - Christian Woehle
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
| | - Sven B. Gould
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
| | - Re-Young Yu
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
| | - Mark van der Giezen
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Aloysius G. M. Tielens
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, Netherlands
| | - William F. Martin
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany
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25
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Novel sterol metabolic network of Trypanosoma brucei procyclic and bloodstream forms. Biochem J 2012; 443:267-77. [PMID: 22176028 DOI: 10.1042/bj20111849] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Trypanosoma brucei is the protozoan parasite that causes African trypanosomiasis, a neglected disease of people and animals. Co-metabolite analysis, labelling studies using [methyl-2H3]-methionine and substrate/product specificities of the cloned 24-SMT (sterol C24-methyltransferase) and 14-SDM (sterol C14demethylase) from T. brucei afforded an uncommon sterol metabolic network that proceeds from lanosterol and 31-norlanosterol to ETO [ergosta-5,7,25(27)-trien-3β-ol], 24-DTO [dimethyl ergosta-5,7,25(27)-trienol] and ergosterol [ergosta-5,7,22(23)-trienol]. To assess the possible carbon sources of ergosterol biosynthesis, specifically 13C-labelled specimens of lanosterol, acetate, leucine and glucose were administered to T. brucei and the 13C distributions found were in accord with the operation of the acetate-mevalonate pathway, with leucine as an alternative precursor, to ergostenols in either the insect or bloodstream form. In searching for metabolic signatures of procyclic cells, we observed that the 13C-labelling treatments induce fluctuations between the acetyl-CoA (mitochondrial) and sterol (cytosolic) synthetic pathways detected by the progressive increase in 13C-ergosterol production (control<[2-(13)C]leucine<[2-(13)C]acetate<[1-(13)C]glucose) and corresponding depletion of cholesta-5,7,24-trienol. We conclude that anabolic fluxes originating in mitochondrial metabolism constitute a flexible part of sterol synthesis that is further fluctuated in the cytosol, yielding distinct sterol profiles in relation to cell demands on growth.
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26
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Comparative analysis of diatom genomes reveals substantial differences in the organization of carbon partitioning pathways. ALGAL RES 2012. [DOI: 10.1016/j.algal.2012.04.003] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Gualdron-López M, Vapola MH, Miinalainen IJ, Hiltunen JK, Michels PAM, Antonenkov VD. Channel-forming activities in the glycosomal fraction from the bloodstream form of Trypanosoma brucei. PLoS One 2012; 7:e34530. [PMID: 22506025 PMCID: PMC3323538 DOI: 10.1371/journal.pone.0034530] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 03/01/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Glycosomes are a specialized form of peroxisomes (microbodies) present in unicellular eukaryotes that belong to the Kinetoplastea order, such as Trypanosoma and Leishmania species, parasitic protists causing severe diseases of livestock and humans in subtropical and tropical countries. The organelles harbour most enzymes of the glycolytic pathway that is responsible for substrate-level ATP production in the cell. Glycolysis is essential for bloodstream-form Trypanosoma brucei and enzymes comprising this pathway have been validated as drug targets. Glycosomes are surrounded by a single membrane. How glycolytic metabolites are transported across the glycosomal membrane is unclear. METHODS/PRINCIPAL FINDINGS We hypothesized that glycosomal membrane, similarly to membranes of yeast and mammalian peroxisomes, contains channel-forming proteins involved in the selective transfer of metabolites. To verify this prediction, we isolated a glycosomal fraction from bloodstream-form T. brucei and reconstituted solubilized membrane proteins into planar lipid bilayers. The electrophysiological characteristics of the channels were studied using multiple channel recording and single channel analysis. Three main channel-forming activities were detected with current amplitudes 70-80 pA, 20-25 pA, and 8-11 pA, respectively (holding potential +10 mV and 3.0 M KCl as an electrolyte). All channels were in fully open state in a range of voltages ±150 mV and showed no sub-conductance transitions. The channel with current amplitude 20-25 pA is anion-selective (P(K+)/P(Cl-)∼0.31), while the other two types of channels are slightly selective for cations (P(K+)/P(Cl-) ratios ∼1.15 and ∼1.27 for the high- and low-conductance channels, respectively). The anion-selective channel showed an intrinsic current rectification that may suggest a functional asymmetry of the channel's pore. CONCLUSIONS/SIGNIFICANCE These results indicate that the membrane of glycosomes apparently contains several types of pore-forming channels connecting the glycosomal lumen and the cytosol.
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Affiliation(s)
- Melisa Gualdron-López
- Research Unit for Tropical Diseases, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Miia H. Vapola
- Department of Biochemistry, Biocenter Oulu, University of Oulu, Oulu, Finland
| | | | - J. Kalervo Hiltunen
- Department of Biochemistry, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Paul A. M. Michels
- Research Unit for Tropical Diseases, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
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Lohr M, Schwender J, Polle JEW. Isoprenoid biosynthesis in eukaryotic phototrophs: a spotlight on algae. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 185-186:9-22. [PMID: 22325862 DOI: 10.1016/j.plantsci.2011.07.018] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 07/25/2011] [Accepted: 07/29/2011] [Indexed: 05/04/2023]
Abstract
Isoprenoids are one of the largest groups of natural compounds and have a variety of important functions in the primary metabolism of land plants and algae. In recent years, our understanding of the numerous facets of isoprenoid metabolism in land plants has been rapidly increasing, while knowledge on the metabolic network of isoprenoids in algae still lags behind. Here, current views on the biochemistry and genetics of the core isoprenoid metabolism in land plants and in the major algal phyla are compared and some of the most pressing open questions are highlighted. Based on the different evolutionary histories of the various groups of eukaryotic phototrophs, we discuss the distribution and regulation of the mevalonate (MVA) and the methylerythritol phosphate (MEP) pathways in land plants and algae and the potential consequences of the loss of the MVA pathway in groups such as the green algae. For the prenyltransferases, serving as gatekeepers to the various branches of terpenoid biosynthesis in land plants and algae, we explore the minimal inventory necessary for the formation of primary isoprenoids and present a preliminary analysis of their occurrence and phylogeny in algae with primary and secondary plastids. The review concludes with some perspectives on genetic engineering of the isoprenoid metabolism in algae.
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Affiliation(s)
- Martin Lohr
- Institut für Allgemeine Botanik, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
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29
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Gualdrón-López M, Brennand A, Hannaert V, Quiñones W, Cáceres AJ, Bringaud F, Concepción JL, Michels PAM. When, how and why glycolysis became compartmentalised in the Kinetoplastea. A new look at an ancient organelle. Int J Parasitol 2011; 42:1-20. [PMID: 22142562 DOI: 10.1016/j.ijpara.2011.10.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 10/13/2011] [Accepted: 10/14/2011] [Indexed: 12/21/2022]
Abstract
A characteristic, well-studied feature of the pathogenic protists belonging to the family Trypanosomatidae is the compartmentalisation of the major part of the glycolytic pathway in peroxisome-like organelles, hence designated glycosomes. Such organelles containing glycolytic enzymes appear to be present in all members of the Kinetoplastea studied, and have recently also been detected in a representative of the Diplonemida, but they are absent from the Euglenida. Glycosomes therefore probably originated in a free-living, common ancestor of the Kinetoplastea and Diplonemida. The initial sequestering of glycolytic enzymes inside peroxisomes may have been the result of a minor mistargeting of proteins, as generally observed in eukaryotic cells, followed by preservation and its further expansion due to the selective advantage of this specific form of metabolic compartmentalisation. This selective advantage may have been a largely increased metabolic flexibility, allowing the organisms to adapt more readily and efficiently to different environmental conditions. Further evolution of glycosomes involved, in different taxonomic lineages, the acquisition of additional enzymes and pathways - often participating in core metabolic processes - as well as the loss of others. The acquisitions may have been promoted by the sharing of cofactors and crucial metabolites between different pathways, thus coupling different redox processes and catabolic and anabolic pathways within the organelle. A notable loss from the Trypanosomatidae concerned a major part of the typical peroxisomal H(2)O(2)-linked metabolism. We propose that the compartmentalisation of major parts of the enzyme repertoire involved in energy, carbohydrate and lipid metabolism has contributed to the multiple development of parasitism, and its elaboration to complicated life cycles involving consecutive different hosts, in the protists of the Kinetoplastea clade.
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Affiliation(s)
- Melisa Gualdrón-López
- Research Unit for Tropical Diseases, de Duve Institute and Laboratory of Biochemistry, Université catholique de Louvain, Avenue Hippocrate 74, Postal Box B1.74.01, B-1200 Brussels, Belgium
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30
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Terashima M, Specht M, Hippler M. The chloroplast proteome: a survey from the Chlamydomonas reinhardtii perspective with a focus on distinctive features. Curr Genet 2011; 57:151-68. [PMID: 21533645 DOI: 10.1007/s00294-011-0339-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 04/05/2011] [Accepted: 04/07/2011] [Indexed: 01/12/2023]
Abstract
The unicellular green alga Chlamydomonas reinhardtii has emerged to be an important model organism for the study of oxygenic eukaryotic photosynthesis as well as other processes occurring in the chloroplast. However, the chloroplast proteome in C. reinhardtii has only recently been comprehensively characterized, made possible by proteomics emerging as an accessible and powerful tool over the last decade. In this review, we introduce a compiled list of 996 experimentally chloroplast-localized proteins for C. reinhardtii, stemming largely from our previous proteomic dataset comparing chloroplasts and mitochondria samples to localize proteins. In order to get a taste of some cellular functions taking place in the C. reinhardtii chloroplast, we will focus this review particularly on metabolic differences between chloroplasts of C. reinhardtii and higher plants. Areas that will be covered are photosynthesis, chlorophyll biosynthesis, carbon metabolism, fermentative metabolism, ferredoxins and ferredoxin-interacting proteins.
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Affiliation(s)
- Mia Terashima
- Department of Biology, Institute of Plant Biology and Biotechnology, University of Münster, Hindenburgplatz 55, 48143, Münster, Germany
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Systems biology from micro-organisms to human metabolic diseases: the role of detailed kinetic models. Biochem Soc Trans 2011; 38:1294-301. [PMID: 20863302 DOI: 10.1042/bst0381294] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Human metabolic diseases are typically network diseases. This holds not only for multifactorial diseases, such as metabolic syndrome or Type 2 diabetes, but even when a single gene defect is the primary cause, where the adaptive response of the entire network determines the severity of disease. The latter may differ between individuals carrying the same mutation. Understanding the adaptive responses of human metabolism naturally requires a systems biology approach. Modelling of metabolic pathways in micro-organisms and some mammalian tissues has yielded many insights, qualitative as well as quantitative, into their control and regulation. Yet, even for a well-known pathway such as glycolysis, precise predictions of metabolite dynamics from experimentally determined enzyme kinetics have been only moderately successful. In the present review, we compare kinetic models of glycolysis in three cell types (African trypanosomes, yeast and skeletal muscle), evaluate their predictive power and identify limitations in our understanding. Although each of these models has its own merits and shortcomings, they also share common features. For example, in each case independently measured enzyme kinetic parameters were used as input. Based on these 'lessons from glycolysis', we will discuss how to make best use of kinetic computer models to advance our understanding of human metabolic diseases.
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Ginger ML, Fritz-Laylin LK, Fulton C, Cande WZ, Dawson SC. Intermediary metabolism in protists: a sequence-based view of facultative anaerobic metabolism in evolutionarily diverse eukaryotes. Protist 2010; 161:642-71. [PMID: 21036663 PMCID: PMC3021972 DOI: 10.1016/j.protis.2010.09.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Protists account for the bulk of eukaryotic diversity. Through studies of gene and especially genome sequences the molecular basis for this diversity can be determined. Evident from genome sequencing are examples of versatile metabolism that go far beyond the canonical pathways described for eukaryotes in textbooks. In the last 2-3 years, genome sequencing and transcript profiling has unveiled several examples of heterotrophic and phototrophic protists that are unexpectedly well-equipped for ATP production using a facultative anaerobic metabolism, including some protists that can (Chlamydomonas reinhardtii) or are predicted (Naegleria gruberi, Acanthamoeba castellanii, Amoebidium parasiticum) to produce H(2) in their metabolism. It is possible that some enzymes of anaerobic metabolism were acquired and distributed among eukaryotes by lateral transfer, but it is also likely that the common ancestor of eukaryotes already had far more metabolic versatility than was widely thought a few years ago. The discussion of core energy metabolism in unicellular eukaryotes is the subject of this review. Since genomic sequencing has so far only touched the surface of protist diversity, it is anticipated that sequences of additional protists may reveal an even wider range of metabolic capabilities, while simultaneously enriching our understanding of the early evolution of eukaryotes.
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Affiliation(s)
- Michael L Ginger
- School of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, UK.
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Abstract
Peroxisomes are organelles bounded by a single membrane that can be found in all major groups of eukaryotes. A single evolutionary origin of this cellular compartment is supported by the presence, in diverse organisms, of a common set of proteins implicated in peroxisome biogenesis and maintenance. Their enzymatic content, however, can vary substantially across species, indicating a high level of evolutionary plasticity. Proteomic analyses have greatly expanded our knowledge on peroxisomes in some model organisms, including plants, mammals and yeasts. However, we still have a limited knowledge about the distribution and functionalities of peroxisomes in the vast majority of groups of microbial eukaryotes. Here, I review recent advances in our understanding of peroxisome diversity and evolution, with a special emphasis on peroxisomes in microbial eukaryotes.
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Affiliation(s)
- Toni Gabaldón
- Centre for Genomic Regulation (CRG), Dr Aiguader, 88 08003 Barcelona, Spain.
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Ginger ML, McFadden GI, Michels PAM. The evolution of organellar metabolism in unicellular eukaryotes. Philos Trans R Soc Lond B Biol Sci 2010; 365:693-8. [PMID: 20124338 DOI: 10.1098/rstb.2009.0260] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Metabolic innovation has facilitated the radiation of microbes into almost every niche environment on the Earth, and over geological time scales transformed the planet on which we live. A notable example of innovation is the evolution of oxygenic photosynthesis which was a prelude to the gradual transformation of an anoxic Earth into a world with oxygenated oceans and an oxygen-rich atmosphere capable of supporting complex multicellular organisms. The influence of microbial innovation on the Earth's history and the timing of pivotal events have been addressed in other recent themed editions of Philosophical Transactions of Royal Society B (Cavalier-Smith et al. 2006; Bendall et al. 2008). In this issue, our contributors provide a timely history of metabolic innovation and adaptation within unicellular eukaryotes. In eukaryotes, diverse metabolic portfolios are compartmentalized across multiple membrane-bounded compartments (or organelles). However, as a consequence of pathway retargeting, organelle degeneration or novel endosymbiotic associations, the metabolic repertoires of protists often differ extensively from classic textbook descriptions of intermediary metabolism. These differences are often important in the context of niche adaptation or the structure of microbial communities. Fundamentally interesting in its own right, the biochemical, cell biological and phylogenomic investigation of organellar metabolism also has wider relevance. For instance, in some pathogens, notably those causing some of the most significant tropical diseases, including malaria, unusual organellar metabolism provides important new drug targets. Moreover, the study of organellar metabolism in protists continues to provide critical insight into our understanding of eukaryotic evolution.
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Affiliation(s)
- Michael L Ginger
- School of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, UK.
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Abstract
SUMMARYEnzymes moonlight in a non-enzymatic capacity in a diverse variety of cellular processes. The discovery of these non-enzymatic functions is generally unexpected, and moonlighting enzymes are known in both prokaryotes and eukaryotes. Importantly, this unexpected multi-functionality indicates that caution might be needed on some occasions in interpreting phenotypes that result from the deletion or gene-silencing of some enzymes, including some of the best known enzymes from classic intermediary metabolism. Here, we provide an overview of enzyme moonlighting in parasitic protists. Unequivocal and putative examples of moonlighting are discussed, together with the possibility that the unusual biological characteristics of some parasites either limit opportunities for moonlighting to arise or perhaps contribute to the evolution of novel proteins with clear metabolic ancestry.
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Martin W. Evolutionary origins of metabolic compartmentalization in eukaryotes. Philos Trans R Soc Lond B Biol Sci 2010; 365:847-55. [PMID: 20124349 PMCID: PMC2817231 DOI: 10.1098/rstb.2009.0252] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Many genes in eukaryotes are acquisitions from the free-living antecedents of chloroplasts and mitochondria. But there is no evolutionary 'homing device' that automatically directs the protein product of a transferred gene back to the organelle of its provenance. Instead, the products of genes acquired from endosymbionts can explore all targeting possibilities within the cell. They often replace pre-existing host genes, or even whole pathways. But the transfer of an enzymatic pathway from one compartment to another poses severe problems: over evolutionary time, the enzymes of the pathway acquire their targeting signals for the new compartment individually, not in unison. Until the whole pathway is established in the new compartment, newly routed individual enzymes are useless, and their genes will be lost through mutation. Here it is suggested that pathways attain novel compartmentation variants via a 'minor mistargeting' mechanism. If protein targeting in eukaryotic cells possesses enough imperfection such that small amounts of entire pathways continuously enter novel compartments, selectable units of biochemical function would exist in new compartments, and the genes could become selected. Dual-targeting of proteins is indeed very common within eukaryotic cells, suggesting that targeting variation required for this minor mistargeting mechanism to operate exists in nature.
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Affiliation(s)
- William Martin
- Institute of Botany III, University of Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
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