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Rampello NG, Stenger M, Westermann B, Osiewacz HD. Impact of F1Fo-ATP-synthase dimer assembly factors on mitochondrial function and organismic aging. MICROBIAL CELL 2018; 5:198-207. [PMID: 29610761 PMCID: PMC5878687 DOI: 10.15698/mic2018.04.625] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In aerobic organisms, mitochondrial F1Fo-ATP-synthase is the major site of ATP production. Beside this fundamental role, the protein complex is involved in shaping and maintenance of cristae. Previous electron microscopic studies identified the dissociation of F1Fo-ATP-synthase dimers and oligomers during organismic aging correlating with a massive remodeling of the mitochondrial inner membrane. Here we report results aimed to experimentally proof this impact and to obtain further insights into the control of these processes. We focused on the role of the two dimer assembly factors PaATPE and PaATPG of the aging model Podospora anserina. Ablation of either protein strongly affects mitochondrial function and leads to an accumulation of senescence markers demonstrating that the inhibition of dimer formation negatively influences vital functions and accelerates organismic aging. Our data validate a model that links mitochondrial membrane remodeling to aging and identify specific molecular components triggering this process.
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Affiliation(s)
- Nadia G Rampello
- Department of Biosciences, Molecular Developmental Biology, Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes, J. W. Goethe University, 60438 Frankfurt, Germany
| | - Maria Stenger
- Cell Biology and Electron Microscopy, University of Bayreuth, 95440 Bayreuth, Germany
| | - Benedikt Westermann
- Cell Biology and Electron Microscopy, University of Bayreuth, 95440 Bayreuth, Germany
| | - Heinz D Osiewacz
- Department of Biosciences, Molecular Developmental Biology, Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes, J. W. Goethe University, 60438 Frankfurt, Germany
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2
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Erdogan CS, Hansen BW, Vang O. Are invertebrates relevant models in ageing research? Focus on the effects of rapamycin on TOR. Mech Ageing Dev 2016; 153:22-9. [PMID: 26763146 DOI: 10.1016/j.mad.2015.12.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 12/24/2015] [Accepted: 12/29/2015] [Indexed: 12/16/2022]
Abstract
Ageing is the organisms increased susceptibility to death, which is linked to accumulated damage in the cells and tissues. Ageing is a complex process regulated by crosstalk of various pathways in the cells. Ageing is highly regulated by the Target of Rapamycin (TOR) pathway activity. TOR is an evolutionary conserved key protein kinase in the TOR pathway that regulates growth, proliferation and cell metabolism in response to nutrients, growth factors and stress. Comparing the ageing process in invertebrate model organisms with relatively short lifespan with mammals provides valuable information about the molecular mechanisms underlying the ageing process faster than mammal systems. Inhibition of the TOR pathway activity via either genetic manipulation or rapamycin increases lifespan profoundly in most invertebrate model organisms. This contribution will review the recent findings in invertebrates concerning the TOR pathway and effects of TOR inhibition by rapamycin on lifespan. Besides some contradictory results, the majority points out that rapamycin induces longevity. This suggests that administration of rapamycin in invertebrates is a promising tool for pursuing the scientific puzzle of lifespan prolongation.
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Affiliation(s)
- Cihan Suleyman Erdogan
- Roskilde University, Department of Science and Environment, Universitetsvej 1, DK-4000, Denmark
| | - Benni Winding Hansen
- Roskilde University, Department of Science and Environment, Universitetsvej 1, DK-4000, Denmark
| | - Ole Vang
- Roskilde University, Department of Science and Environment, Universitetsvej 1, DK-4000, Denmark.
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Esser K, Kück U, Stahl U, Tudzynski P. Mitochondrial DNA and senescence in Podospora anserina. Curr Genet 2013; 4:83. [PMID: 24185873 DOI: 10.1007/bf00376791] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/1981] [Indexed: 11/28/2022]
Affiliation(s)
- K Esser
- Lehrstuhl für Allgemeine Botanik, Ruhr-Universität, Postfach 102148, D-4630, Bochum 1, Germany
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5
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Ethidium bromide rejuvenation of senescent cultures of Podospora anserina : Loss of senescence-specific DNA and recovery of normal mitochondrial DNA. Curr Genet 2013; 8:127-34. [PMID: 24177587 DOI: 10.1007/bf00420231] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/1983] [Indexed: 10/26/2022]
Abstract
The effect of ethidium bromide (EB) which is known to be able to "rejuvenate" senescent mycelia in Podospora anserina, has been investigated at the level of the mitochondrial DNA (mtDNA) by restriction analysis and molecular hybridization. While senescent mycelia display a very low growth ability and gross mtDNA modifications (tandem amplification of short sequences and disorganization of the mitochondrial chromosome: deletion of large sequences), the rejuvenated mycelia display a normal life span and contain a mtDNA in all respects identical to that of wild type mycelium (neither circular molecules nor amplified fragments could be detected). These results demonstrate a strict correlation between the senescent state and the presence of amplified mtDNA and suggest that EB rejuvenation could proceed by an efficient selection of intact mitochondrial chromosomes still present in senescent cultures.
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6
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Transcription of a mitochondrial plasmid during senescence in Podospora anserina. Curr Genet 2013; 7:457-64. [PMID: 24173452 DOI: 10.1007/bf00377611] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/1983] [Indexed: 10/26/2022]
Abstract
In the ascomycete fungus Podospora anserina, cellular senescence is characterized by the excision, circularization, and amplification of specific segments of the non-senescent mitochondrial genome. During senescence, various plasmids can be found in the mitochondria, and different senescent events produce different plasmid populations. In this paper we have examined the transcriptional activity of one mitochondrial plasmid (α-sen DNA) and have contrasted this with the non-senescent mitochondrial genome of rapidly (A(+)) and slowly (s(+)) senescing races. In non-senescent and senescent mitochondria we observe two RNAs which are homologous to α-sen DNA and to the parental locus on the native genome. These are 2.4 and 2.5 kb long and have different 5' ends while overlapping throughout most of their lengths. They may represent different transcripts for α-sen DNA and the parental genome and indicate that excision of the plasmid begins 450 bp from the 5' end of the genomic coding sequence. Transcription of the α-sen DNA plasmid appears to be active in both senescent and in non-senescent mycelia.
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Age-related changes in the mitochondrial proteome of the fungus Podospora anserina analyzed by 2D-DIGE and LC-MS/MS. J Proteomics 2013; 91:358-74. [PMID: 23872087 DOI: 10.1016/j.jprot.2013.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 06/18/2013] [Accepted: 07/08/2013] [Indexed: 12/28/2022]
Abstract
UNLABELLED Many questions concerning the molecular processes during biological aging remain unanswered. Since mitochondria are central players in aging, we applied quantitative two-dimensional difference gel electrophoresis (2D-DIGE) coupled to protein identification by mass spectrometry to study the age-dependent changes in the mitochondrial proteome of the fungus Podospora anserina - a well-established aging model. 67 gel spots exhibited significant, but remarkably moderate intensity changes. While typically the observed changes in protein abundance occurred progressively with age, for several proteins a pronounced change was observed at late age, sometimes inverting the trend observed at younger age. The identified proteins were assigned to a wide range of metabolic pathways including several implicated previously in biological aging. An overall decrease for subunits of complexes I and V of oxidative phosphorylation was confirmed by Western blot analysis and blue-native electrophoresis. Changes in several groups of proteins suggested a general increase in protein biosynthesis possibly reflecting a compensatory mechanism for increased quality control-related protein degradation at later age. Age-related augmentation in abundance of proteins involved in biosynthesis, folding, and protein degradation pathways sustain these observations. Furthermore, a significant decrease of two enzymes involved in the degradation of γ-aminobutyrate (GABA) supported its previously suggested involvement in biological aging. BIOLOGICAL SIGNIFICANCE We have followed the time course of changes in protein abundance during aging of the fungus P. anserina. The observed moderate but significant changes provide insight into the molecular adaptations to biological aging and highlight the metabolic pathways involved, thereby offering new leads for future research.
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Scheckhuber CQ, Houthoofd K, Weil AC, Werner A, De Vreese A, Vanfleteren JR, Osiewacz HD. Alternative oxidase dependent respiration leads to an increased mitochondrial content in two long-lived mutants of the aging model Podospora anserina. PLoS One 2011; 6:e16620. [PMID: 21305036 PMCID: PMC3029406 DOI: 10.1371/journal.pone.0016620] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 01/07/2011] [Indexed: 01/29/2023] Open
Abstract
The retrograde response constitutes an important signalling pathway from mitochondria to the nucleus which induces several genes to allow compensation of mitochondrial impairments. In the filamentous ascomycete Podospora anserina, an example for such a response is the induction of a nuclear-encoded and iron-dependent alternative oxidase (AOX) occurring when cytochrome-c oxidase (COX) dependent respiration is affected. Several long-lived mutants are known which predominantly or exclusively respire via AOX. Here we show that two AOX-utilising mutants, grisea and PaCox17::ble, are able to compensate partially for lowered OXPHOS efficiency resulting from AOX-dependent respiration by increasing mitochondrial content. At the physiological level this is demonstrated by an elevated oxygen consumption and increased heat production. However, in the two mutants, ATP levels do not reach WT levels. Interestingly, mutant PaCox17::ble is characterized by a highly increased release of the reactive oxygen species (ROS) hydrogen peroxide. Both grisea and PaCox17::ble contain elevated levels of mitochondrial proteins involved in quality control, i. e. LON protease and the molecular chaperone HSP60. Taken together, our work demonstrates that AOX-dependent respiration in two mutants of the ageing model P. anserina is linked to a novel mechanism involved in the retrograde response pathway, mitochondrial biogenesis, which might also play an important role for cellular maintenance in other organisms.
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Affiliation(s)
- Christian Q Scheckhuber
- Faculty for Biosciences, Molecular Developmental Biology, Cluster of Excellence Macromolecular Complexes, Johann Wolfgang Goethe University, Frankfurt, Germany.
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van Diepeningen AD, Goedbloed DJ, Slakhorst SM, Koopmanschap AB, Maas MFPM, Hoekstra RF, Debets AJM. Mitochondrial recombination increases with age in Podospora anserina. Mech Ageing Dev 2010; 131:315-22. [PMID: 20226205 DOI: 10.1016/j.mad.2010.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 03/02/2010] [Accepted: 03/03/2010] [Indexed: 12/15/2022]
Abstract
With uniparental inheritance of mitochondria, there seems little reason for homologous recombination in mitochondria, but the machinery for mitochondrial recombination is quite well-conserved in many eukaryote species. In fungi and yeasts heteroplasmons may be formed when strains fuse and transfer of organelles takes place, making it possible to study mitochondrial recombination when introduced mitochondria contain different markers. A survey of wild-type isolates from a local population of the filamentous fungus Podospora anserina for the presence of seven optional mitochondrial introns indicated that mitochondrial recombination does take place in nature. Moreover the recombination frequency appeared to be correlated with age: the more rapidly ageing fraction of the population had a significantly lower linkage disequilibrium indicating more recombination. Direct confrontation experiments with heterokaryon incompatible strains with different mitochondrial markers at different (relative) age confirmed that mitochondrial recombination increases with age. We propose that with increasing mitochondrial damage over time, mitochondrial recombination - even within a homoplasmic population of mitochondria - is a mechanism that may restore mitochondrial function.
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Affiliation(s)
- Anne D van Diepeningen
- Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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10
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van Diepeningen AD, Slakhorst SM, Koopmanschap AB, Ikink GJ, Debets AJM, Hoekstra RF. Calorie restriction in the filamentous fungus Podospora anserina. Exp Gerontol 2010; 45:516-24. [PMID: 20064602 DOI: 10.1016/j.exger.2010.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 01/04/2010] [Accepted: 01/06/2010] [Indexed: 11/27/2022]
Abstract
Calorie restriction (CR) is a regimen of reduced food intake that, although the underlying mechanism is unknown, in many organisms leads to life span extension. Podospora anserina is one of the few known ageing filamentous fungi and the ageing process and concomitant degeneration of mitochondria have been well-studied. CR in P. anserina increases not only life span but also forestalls the ageing-related decline in fertility. Here we review what is known about CR in P. anserina and about possibly involved mechanisms like enhanced mitochondrial stability, reduced production of reactive oxygen species and changes in the OXPHOS machinery. Additionally, we present new microscopic data on mitochondrial dynamics under rich nutritional and CR conditions at different points in life. Lines that have grown under severe CR for more than 50x the normal life span, show no accumulation of age-related damage, though fecundity is reduced in some of these lines. Finally, we discuss the possible role of CR in P. anserina in nature and the effect of CR at different points in life.
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Affiliation(s)
- Anne D van Diepeningen
- Laboratory of Genetics, Plant Sciences, Wageningen University, Wageningen, The Netherlands.
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11
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Soerensen M, Gredilla R, Müller-Ohldach M, Werner A, Bohr VA, Osiewacz HD, Stevnsner T. A potential impact of DNA repair on ageing and lifespan in the ageing model organism Podospora anserina: decrease in mitochondrial DNA repair activity during ageing. Mech Ageing Dev 2009; 130:487-96. [PMID: 19486911 DOI: 10.1016/j.mad.2009.05.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Accepted: 05/21/2009] [Indexed: 12/21/2022]
Abstract
The free radical theory of ageing states that ROS play a key role in age-related decrease in mitochondrial function via the damage of mitochondrial DNA (mtDNA), proteins and lipids. In the sexually reproducing ascomycete Podospora anserina ageing is, as in other eukaryotes, associated with mtDNA instability and mitochondrial dysfunction. Part of the mtDNA instabilities may arise due to accumulation of ROS induced mtDNA lesions, which, as previously suggested for mammals, may be caused by an age-related decrease in base excision repair (BER). Alignments of known BER protein sequences with the P. anserina genome revealed high homology. We report for the first time the presence of BER activities in P. anserina mitochondrial extracts. DNA glycosylase activities decrease with age, suggesting that the increased mtDNA instability with age may be caused by decreased ability to repair mtDNA damage and hence contribute to ageing and lifespan control in this ageing model. Additionally, we find low DNA glycosylase activities in the long-lived mutants grisea and DeltaPaCox17::ble, which are characterized by low mitochondrial ROS generation. Overall, our data identify a potential role of mtDNA repair in controlling ageing and life span in P. anserina, a mechanism possibly regulated in response to ROS levels.
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Affiliation(s)
- Mette Soerensen
- Danish Centre for Molecular Gerontology and Danish Aging Research Center, Aarhus University, Department of Molecular Biology, University of Aarhus, Aarhus C, Denmark
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12
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Scheckhuber CQ, Osiewacz HD. Podospora anserina: a model organism to study mechanisms of healthy ageing. Mol Genet Genomics 2008; 280:365-74. [PMID: 18797929 DOI: 10.1007/s00438-008-0378-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 08/29/2008] [Indexed: 12/18/2022]
Abstract
The filamentous ascomycete Podospora anserina has been extensively studied as an experimental ageing model for more than 50 years. As a result, a huge body of data has been accumulated and various molecular pathways have been identified as part of a molecular network involved in the control of ageing and life span. The aim of this review is to summarize data on P. anserina ageing, including aspects like respiration, cellular copper homeostasis, mitochondrial DNA (mtDNA) stability/instability, mitochondrial dynamics, apoptosis, translation efficiency and pathways directed against oxidative stress. It becomes clear that manipulation of several of these pathways bears the potential to extend the healthy period of time, the health span, within the life time of the fungus. Here we put special attention on recent work aimed to identify and characterize this type of long-lived P. anserina mutants. The study of the molecular pathways which are modified in these mutants can be expected to provide important clues for the elucidation of the mechanistic basis of this type of 'healthy ageing' at the organism level.
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Affiliation(s)
- Christian Q Scheckhuber
- Cluster of Excellence Macromolecular Complexes and Faculty for Biosciences, Molecular Developmental Biology, Johann Wolfgang Goethe University, Max-von-Laue-Str. 9, 60438, Frankfurt/Main, Germany
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13
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Osiewacz HD, Scheckhuber CQ. Impact of ROS on ageing of two fungal model systems: Saccharomyces cerevisiae and Podospora anserina. Free Radic Res 2007; 40:1350-8. [PMID: 17090424 DOI: 10.1080/10715760600921153] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
To provide a foundation for the development of effective interventions to counteract various age-related diseases in humans, ageing processes have been extensively studied in various model organisms and systems. However, the mechanisms underlying ageing are still not unravelled in detail in any system including rather simple organisms. In this article, we review some of the molecular mechanisms that were found to affect ageing in two fungal models, the unicellular ascomycete Saccharomyces cerevisiae and the filamentous ascomycete Podospora anserina. A selection of issues like retrograde response, genomic instability, caloric restriction, mtDNA reorganisation and apoptosis is presented and discussed with special emphasis on the role reactive oxygen species (ROS) play in these diverse molecular pathways.
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Affiliation(s)
- Heinz D Osiewacz
- Institute of Molecular Biosciences, Molecular Developmental Biology, Johann Wolfgang Goethe University, Frankfurt, Germany.
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Koll F, Begel O, Belcour L. Insertion of short poly d(A) d(T) sequences at recombination junctions in mitochondrial DNA of Podospora. ACTA ACUST UNITED AC 2006; 209:630-2. [PMID: 17193717 DOI: 10.1007/bf00331176] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We have characterized the DNA sequences at recombination points in the mitochondrial DNA of two independent mitochondrial mutants of Podospora anserina. These sequences reveal the presence of foreign DNA at each recombination border, consisting of short stretches of A and T residues. We discuss the possible origin of this DNA and suggest the involvement of a reverse transcriptase activity.
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Affiliation(s)
- F Koll
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, F-91190 Gif sur Yvette, France
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15
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Scheckhuber CQ, Erjavec N, Tinazli A, Hamann A, Nyström T, Osiewacz HD. Reducing mitochondrial fission results in increased life span and fitness of two fungal ageing models. Nat Cell Biol 2006; 9:99-105. [PMID: 17173038 DOI: 10.1038/ncb1524] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Accepted: 10/31/2006] [Indexed: 11/08/2022]
Abstract
Ageing of biological systems is accompanied by alterations in mitochondrial morphology, including a transformation from networks and filaments to punctuate units. The significance of these alterations with regard to ageing is not known. Here, we demonstrate that the dynamin-related protein 1 (Dnm1p), a mitochondrial fission protein conserved from yeast to humans, affects ageing in the two model systems we studied, Podospora anserina and Saccharomyces cerevisiae. Deletion of the Dnm1 gene delays the transformation of filamentous to punctuate mitochondria and retards ageing without impairing fitness and fertility typically observed in long-lived mutants. Our data further suggest that reduced mitochondrial fission extends life span by increasing cellular resistance to the induction of apoptosis and links mitochondrial dynamics, apoptosis and life-span control.
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Affiliation(s)
- C Q Scheckhuber
- Johann Wolfgang Goethe University, Institute of Molecular Biosciences, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
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16
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Abstract
Fungi are eukaryotic microorganisms studied in various areas of general and applied biology. A few species were among the first systems in which specific aspects of aging were addressed experimentally. Various factors, both environmental and genetic, were found to affect lifespan and aging. Mitochondrial pathways play a paramount role. Since mitochondria are semiautonomous organelles and depend on both nuclear as well as mitochondrial genes, mitochondrial-nuclear interactions are of major relevance. As a main generator of reactive oxygen species (ROS), mitochondria are prone to molecular damage. However, cells can cope with the negative effects of ROS utilizing different scavenging systems and, once defects became manifested, by repair of damaged molecules. Both, lowering ROS generation and increasing mitochondrial "caretaker" systems bear great potential to interfere with natural aging processes.
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Affiliation(s)
- Heinz D Osiewacz
- Botanisches Institut, Johann Wolfgang Goethe-Universität, Molekulare Entwicklungsbiologie und Biotechnologie, Marie-Curie-Str. 9, D-60439, Frankfurt/Main, Germany.
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Abstract
In experimental gerontology, there is a long tradition in the use of both unicellular and filamentous species of fungi. In the last three decades, biochemical, genetic and molecular approaches have proved very fruitful in elucidating different aspects of ageing. It was shown that various genes and molecular pathways are involved in life span control. The oxygenic energy metabolism plays a central role. During mitochondrial energy transduction, reactive oxygen species (ROS) are generated as by-products. These molecules are able to damage all cellular compounds leading to cellular dysfunctions. Within certain limits, however, cells are able to cope with ROS-related problems. First, ROS scavengers can be induced which are effective in lowering the molecular burden of ROS on cellular functions. Second, if damage occurs, specific repair mechanisms and the general turnover of affected molecules can maintain cellular functions. Finally, if damage of essential components is too severe, cells may induce specific pathways to compensate for the corresponding impairments. A coordinated interaction between different cellular compartments is involved in these processes. In this review I shall concentrate on the ageing in the filamentous ascomycete Podospora anserina. It is clear that both environmental as well as genetic traits are involved in the control of life span and that mitochondrial-nuclear interactions play a paramount role.
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Affiliation(s)
- Heinz D Osiewacz
- Molekulare Entwicklungsbiologie und Biotechnologie, Botanisches Institut, Johann Wolfgang Goethe-Universität, Marie-Curie-Street 9, D-60439, Frankfurt am Main, Germany.
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18
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Abstract
In the filamentous ascomycete Podospora anserina mitochondria play a major role in lifespan control. Since the function of these organelles depends on a large number of individual components it is no surprise that a complex network of interacting branches of individual molecular pathways is involved in this process. Recently, the nuclear encoded transcription factor GRISEA was found to significantly affect mitochondrial functions. GRISEA is involved in the control of cellular copper homeostasis. Most importantly, the high affinity uptake of copper from the environment is controlled by this transcription factor. Once copper has entered the cell, it becomes distributed to different compartments and different target molecules. This process depends on a group of proteins, termed copper chaperones. PaCOX17, a homologue of the yeast copper chaperone yCOX17, appears to be involved in copper delivery to mitochondria. Most importantly, the metal is crucial for the assembly and the function of complex IV of the respiratory chain. However, although P. anserina is an obligate aerobe and therefore depends on mitochondrial energy transduction, impairments in the copper delivery pathway are not lethal. This is due to the induction of a molecular back-up system able to compensate for deficiencies in complex IV. The system utilizes an alternative oxidase (PaAOX) which uses iron instead of copper as a cofactor. The alternative respiratory pathway is characterized by a decreased ATP generation but, most significantly, also a decrease in the production of reactive oxygen species. Consequently, molecular damage is reduced which contributes to an increased lifespan of this type of mutant. In addition, modifications in the availability of cellular copper have other relevant consequences. Most significantly, the characteristic age-related rearrangements occurring in the mitochondrial DNA of wild-type strains of P. anserina were found to be dependent on the availability of copper.
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Affiliation(s)
- Heinz D Osiewacz
- Johann Wolfgang Goethe-Universität, Botanisches Institut, Molekulare Entwicklungsbiologie und Biotechnologie, Marie-Curie-Strasse 9, D-60439 Frankfurt/Main, Germany.
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19
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Osiewacz HD, Borghouts C. Mitochondrial oxidative stress and aging in the filamentous fungus Podospora anserina. Ann N Y Acad Sci 2000; 908:31-9. [PMID: 10911945 DOI: 10.1111/j.1749-6632.2000.tb06633.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the filamentous fungus Podospora anserina, mitochondrial oxidative stress is a major contributor to aging. Reactive oxygen species (ROS) generated as a result of electron leakage during respiration lead to damage of components of the electron transport chain. In aging wild-type cultures, damaged proteins cannot be replaced because the mitochondrial genes encoding some of the corresponding subunits gradually become deleted from the mitochondrial DNA (mtDNA). Consequently, these defects result in an increased generation of reactive oxygen species and respiration deficits leading to cell death. Analyses of wild-type strains and of different long-lived mutants of P. anserina provide strong evidence that molecular mechanisms controlling aging processes in this fungus are complex and act at different levels. A basic mechanism (e.g., damage by ROS) appears to be overlaid by prominent instabilities of the mtDNA.
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Affiliation(s)
- H D Osiewacz
- Johann Wolfgang Goethe-Universität, Botanisches Institut, Frankfurt am Main, Germany.
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20
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Borghouts C, Kimpel E, Osiewacz HD. Mitochondrial DNA rearrangements of Podospora anserina are under the control of the nuclear gene grisea. Proc Natl Acad Sci U S A 1997; 94:10768-73. [PMID: 9380708 PMCID: PMC23480 DOI: 10.1073/pnas.94.20.10768] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Podospora anserina is a filamentous fungus with a limited life span. Life span is controlled by nuclear and extranuclear genetic traits. Herein we report the nature of four alterations in the nuclear gene grisea that lead to an altered morphology, a defect in the formation of female gametangia, and an increased life span. Three sequence changes are located in the 5' upstream region of the grisea ORF. One mutation is a G --> A transition at the 5' splice site of the single intron of the gene, leading to a RNA splicing defect. This loss-of-function affects the amplification of the first intron of the mitochondrial cytochrome c oxidase subunit I gene (COI) and the specific mitochondrial DNA rearrangements that occur during senescence of wild-type strains. Our results indicate that the nuclear gene grisea is part of a molecular machinery involved in the control of mitochondrial DNA reorganizations. These DNA instabilities accelerate but are not a prerequisite for the aging of P. anserina cultures.
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Affiliation(s)
- C Borghouts
- Molekulare Entwicklungsbiologie und Biotechnologie, Johann Wolfgang Goethe-Universität, Botanisches Institut, Marie-Curie-Str. 9, D-60439 Frankfurt am Main, Germany
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Osiewacz HD, Nuber U. GRISEA, a putative copper-activated transcription factor from Podospora anserina involved in differentiation and senescence. MOLECULAR & GENERAL GENETICS : MGG 1996; 252:115-24. [PMID: 8804410 DOI: 10.1007/bf02173211] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Podospora anserina is a filamentous fungus with a limited lifespan. Lifespan is controlled by both environmental and genetic factors. Using a combination of genetic and molecular approaches we have cloned one of these factors, gerontogene grisea. The cloned wild-type copy of grisea complements the altered morphological characteristics (e.g., colony and ascospore color), the defect in gametangia development, and the increased lifespan of the pleiotropic mutant grisea. A molecular analysis revealed that grisea is a discontinuous gene with a single intron. The deduced amino acid sequence shows significant homology to MAC1, ACE1 and AMT1, indicating that GRISEA, like the proteins from Saccharomyces cerevisiae (MAC1 and ACE1) and Candida glabrata (AMT1), codes for a copper-activated transcription factor. This conclusion is consistent with the pleiotropic nature of the grisea phenotype. We suggest that the gerontoprotein GRISEA is one component of a transcription apparatus involved in the genetic control of morphogenesis and aging.
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Affiliation(s)
- H D Osiewacz
- Abteilung Molekularbiologie der Alterungsprozesse, Deutsches Krebsforschungszentrum, Heidelberg, Germany
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22
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Schwartz T, Osiewacz HD. Telomere length does not change during senescence of the ascomycete Podospora anserina. Mutat Res 1996; 316:193-9. [PMID: 8649454 DOI: 10.1016/s0921-8734(96)90003-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
All strains of the filamentous fungus Podospora anserina are characterized by a well defined life span. Senescence is controlled by nuclear and extranuclear genetic traits. In order to test whether or not the ends of the chromosomes of this ascomycete shorten during senescence and thus telomere shortening may be linked to the well analyzed, age-related reorganizations of the mitochondrial DNA (mtDNA), we analyzed the genomic DNA of P. anserina wild-type strain s. We found that, although the mtDNA becomes reorganized when cultures age, the telomeres remain constant suggesting that telomere shortening does not play a major role in normal aging of this particular biological system.
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Affiliation(s)
- T Schwartz
- Deutsches Krebsforschungszentrum, Angewandte Tumorvirologie, Abteilung Molekularbiologie der Alterungsprozesse, Heidelberg, Germany
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23
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Hermanns J, Debets F, Hoekstra R, Osiewacz HD. A novel family of linear plasmids with homology to plasmid pAL2-1 of Podospora anserina. MOLECULAR & GENERAL GENETICS : MGG 1995; 246:638-47. [PMID: 7700237 DOI: 10.1007/bf00298971] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Three recently isolated wild-type strains of the ascomycete Podospora anserina were analyzed for the presence of linear mitochondrial plasmids. In one of these strains, designated Wat, at least 12 distinct plasmid-like elements were identified. From molecular analyses a minimum number of 78 individual linear molecules with proteins bound to their 5' ends was estimated. In addition, the different members of this family of typical linear plasmids were shown to possess a common central region and terminal sequences which differ from one plasmid to another due to the presence of different numbers of a 2.4 kb sequence module. Finally, the pWa6 plasmids share a high degree of sequence similarity with pAL2-1, a linear plasmid previously identified in mitochondria of a long-lived mutant of P.anserina. A mechanism is proposed which explains the generation of these distinct, closely related extra-chromosomal genetic traits.
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Affiliation(s)
- J Hermanns
- German Cancer Research Center, Department of Molecular Biology of Aging Processes, Heidelberg
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24
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Jamet-Vierny C, Shechter E. Senescence-specific mitochondrial DNA molecules in P. anserina: evidence for transcription and normal processing of the RNA. Curr Genet 1994; 25:538-44. [PMID: 8082206 DOI: 10.1007/bf00351675] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In Podospora anserina the phenomenon of senescence was previously shown to be correlated with the presence of senescence-specific circular DNAs (senDNAs), resulting from the amplification of distinct regions (alpha, beta, gamma and epsilon) of the mitochondrial chromosome. The beta region gives rise to senDNAs with variable sizes, but sharing a 1-kb common sequence. Here, we present a molecular analysis of five beta senDNAs. We have determined the nucleotide sequence around the circularization site of each senDNA monomer. In two cases, the presence of a tRNA gene, very close to the 3' end of the monomer, has been observed. This suggests that some beta senDNAs could be generated via a reverse transcription step. We have furthermore shown that the beta senDNAs produce specific transcripts which undergo normal processing of their introns. We propose that a transcription start site, located in the beta common region, is involved in mitochondrial replication allowing the amplification of the beta senDNAs.
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Affiliation(s)
- C Jamet-Vierny
- Centre de Génétique Moléculaire, CNRS, Gif-sur-Yvette, France
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25
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Abstract
Among mobile genetic elements, self-splicing introns are of particular interest. They belong to either group I or group II depending on their three-dimensional structure. Homing, the systematic intron invasion of an intronless gene when it encounters its homologous intron-bearing allele, is the only means for intron mobility so far demonstrated. It depends on the activity of the intron-encoded protein and is very specific for the acceptor site. Intron transposition, the transfer of an intron to a novel site, predicted on the basis of phylogenetic studies and in vitro reverse-splicing experiments, has been proposed to be responsible for evolutionary intron spreading. Here we present results from polymerase chain reaction experiments consistent with transposition of a group II intron. This event is proposed to account for the site-specific deletion in the mitochondrial chromosome of the fungus Podospora anserina that is associated with the premature death syndrome and might also be involved in the senescence process affecting this species.
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Affiliation(s)
- C H Sellem
- Centre de Génétique Moléculaire CNRS, Gif-sur-Yvette, France
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26
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Abstract
Longevity varies between and within species. The existence of species-specific limit to human life-span and its partial heritability indicate the existence of genetic factors that influence the ageing process. Insight into the nature of these genetic factors is provided by evolutionary studies, notably the disposable soma theory, which suggests a central role of energy metabolism in determining life-span. Energy is important in two ways. First, the disposable soma theory indicates that the optimum energy investment in cell maintenance and repair processes will be tuned through natural selection to provide adequate, but not excessive, protection against random molecular damages (e.g. to DNA, proteins). All that is required is that the organism remains in a sound condition through its natural expectation of life in the wild environment, where accidents are the predominant cause of mortality. Secondly, energy is implicated because of the intrinsic vulnerability of mitochondria to damage that may interfere with the normal supply of energy to the cell via the oxidative phosphorylation pathways. Oxidative phosphorylation produces ATP, and as a by-product also produces highly reactive oxygen radicals that can damage many cell structures, including the mitochondria themselves. Several lines of evidence link, on the one hand, oxidative damage to cell ageing, and on the other hand, energy-dependent antioxidant defences to the preservation of cellular homeostasis, and hence, longevity. Models of cellular ageing in vitro allow direct investigation of mechanisms, such as oxidative damage, that contribute to limiting human life-span. The genetic substratum of inter-individual differences in longevity may be unraveled by a two-pronged reverse genetics approach: sibling pair analysis applied to nonagenarian and centenarian siblings, combined with association studies of centenarians, may lead to the identification of genetic influences upon human longevity. These studies have become practicable thanks to recent progress in human genome mapping, especially to the development of microsatellite markers and the integration of genetic and physical maps.
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Affiliation(s)
- F Schächter
- Centre d'Etude du Polymorphisme Humain, Paris, France
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27
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Osiewacz HD, Hermanns J. The role of mitochondrial DNA rearrangements in aging and human diseases. AGING (MILAN, ITALY) 1992; 4:273-86. [PMID: 1294242 DOI: 10.1007/bf03324108] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Instabilities and point mutations of the high molecular weight mitochondrial DNA (mtDNA) were shown to be correlated with various degenerative processes in both lower eukaryotes as well as in mammals. In filamentous fungi, circular and linear plasmids were demonstrated to be involved in mtDNA rearrangements and in the genetic control of senescence. In addition, in these eukaryotic microorganisms, which have proved to be ideal model systems in experimental gerontology, a number of nuclear genes were identified controlling the stability of the mitochondrial genome. Although the mitochondrial genome of mammals, including humans, appears to be quite stable in comparison to other species, mtDNA instabilities of the type described in fungi were observed in mitochondria of patients with different mitochondrial degenerative disorders (CPEO, KSS, Pearson syndrome, LHON, MERRF, MELAS). It was later demonstrated that such mtDNA rearrangements appear to accumulate progressively during aging in human subjects. These data suggest that instabilities of the mitochondrial genome may play an important role in the control of life span not only in lower eukaryotes, but also in humans.
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Affiliation(s)
- H D Osiewacz
- Deutsches Krebsforschungszentrum, Institut für Virusforschung, Heidelberg, Germany
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28
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Hermanns J, Osiewacz HD. The linear mitochondrial plasmid pAL2-1 of a long-lived Podospora anserina mutant is an invertron encoding a DNA and RNA polymerase. Curr Genet 1992; 22:491-500. [PMID: 1473181 DOI: 10.1007/bf00326415] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The molecular characterization of an additional DNA species (pAL2-1) which was identified previously in a long-lived extrachromosomal mutant (AL2) of Podospora anserina revealed that this element is a mitochondrial linear plasmid. pAL2-1 is absent from the corresponding wild-type strain, has a size of 8395 bp and contains perfect long terminal inverted repeats (TIRs) of 975 bp. Exonuclease digestion experiments indicated that proteins are covalently bound at the 5' termini of the plasmid. Two long, non-overlapping open reading frames, ORF1 (3,594 bp) and ORF2 (2847 bp), have been identified, which are located on opposite strands and potentially encode a DNA and an RNA polymerase, respectively. The ORF1-encoded polypeptide contains three conserved regions which may be responsible for a 3'-5' exonuclease activity and the typical consensus sequences for DNA polymerases of the D type. In addition, an amino-acid sequence motif (YSRLRT), recently shown to be conserved in terminal proteins from various bacteriophages, has been identified in the amino-terminal part of the putative protein. According to these properties, this first linear plasmid identified in P. anserina shares all characteristics with invertrons, a group of linear mobile genetic elements.
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Affiliation(s)
- J Hermanns
- Deutsches Krebsforschungszentrum, Forschungsschwerpunkt: Angewandte Tumorvirologie, Abteilung: Molekularbiologie der Alterungsprozesse, Heidelberg, Federal Republic of Germany
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29
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Jacobs JD, Ludwig JR, Hildebrand M, Kukel A, Feng TY, Ord RW, Volcani BE. Characterization of two circular plasmids from the marine diatom Cylindrotheca fusiformis: plasmids hybridize to chloroplast and nuclear DNA. MOLECULAR & GENERAL GENETICS : MGG 1992; 233:302-10. [PMID: 1603070 DOI: 10.1007/bf00587592] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This paper reports the discovery and initial characterization of two small plasmids, pCf1 and pCf2, in the marine diatom Cylindrotheca fusiformis. Extracted diatom DNA separates into two bands in CsCl-Hoechst 33258 dye gradients. Upon agarose gel electrophoresis of a sample of the upper band of the gradient we observed, in addition to high molecular weight (genomic) chloroplast and mitochondrial DNA, pairs of lower molecular weight bands. These bands contained two species of circular plasmid DNA molecules, as shown by electron microscopy. The nucleotide composition of the plasmids, and chloroplast and mitochondrial DNAs is similar, as indicated by their co-banding in the gradients. They were cloned, and their restriction maps determined, showing that pCf1 is 4.27 and pCf2 4.08 kb in size. By hybridization analysis, we showed that pCf1 and pCf2 share regions of similarity, but not identity. Neither plasmid hybridizes with mitochondrial DNA. Both plasmids hybridize with chloroplast DNA, and pCf2 also hybridizes with nuclear DNA.
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Affiliation(s)
- J D Jacobs
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla 92093
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30
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Sellem CH, Sainsard-Chanet A, Belcour L. Detection of a protein encoded by a class II mitochondrial intron of Podospora anserina. MOLECULAR & GENERAL GENETICS : MGG 1990; 224:232-40. [PMID: 2277641 DOI: 10.1007/bf00271556] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the filamentous fungus Podospora anserina, the amplification as circular DNA molecules of the first intron (intron alpha) of the CO1 mitochondrial gene, encoding the cytochrome oxidase subunit 1, is known to be strongly associated with aging of strains. In this study we have attempted to detect the protein potentially encoded by the open reading frame (ORF) contained in this intron. This was done by the Western blot technique using specific antisera raised against three polypeptides encoded by three non-overlapping fragments of this ORF adapted to the universal code and overexpressed in Escherichia coli. We examined about thirty independent subclones of Podospora derived from two different geographic races (A, s), using wild-type and mutant strains, young and senescent cultures. A 100 kDa polypeptide, encoded by the class II intron alpha, was detected in five senescent subclones which all showed strong amplification of the intronic alpha sequence (Sen DNA alpha).
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Affiliation(s)
- C H Sellem
- Centre de Génétique Moléculaire, C.N.R.S., Gif-sur-Yvette, France
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31
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Abstract
The ability of eukaryotic organisms of the same genotype to vary in developmental pattern or in phenotype according to varying environmental conditions is frequently associated with changes in extrachromosomal circular DNA (eccDNA) sequences. Although variable in size, sequence complexity, and copy number, the best characterized of these eccDNAs contain sequences homologous to chromosomal DNA which indicates that they might arise from genetic rearrangements, such as homologous recombination. The abundance of repetitive sequence families in eccDNAs is consistent with the notion that tandem repeats and dispersed repetitive elements participate in intrachromosomal recombination events. There is also evidence that a fraction of this DNA has characteristics similar to retrotransposons. It has been suggested that eccDNAs could reflect altered patterns of gene expression or an instability of chromosomal sequences during development and aging. This article reviews some of the findings and concepts regarding eccDNAs and sequence plasticity in eukaryotic genomes.
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Affiliation(s)
- J W Gaubatz
- Department of Biochemistry, University of South Alabama College of Medicine, Mobile 36688
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32
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Affiliation(s)
- H D Osiewacz
- Lehrstuhl für Allgemeine Botanik, Ruhr-Universität, Bochum, F.R.G
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33
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34
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Vierny-Jamet C. Senescence in Podospora anserina: a possible role for nucleic acid interacting proteins suggested by the sequence analysis of a mitochondrial DNA region specifically amplified in senescent cultures. Gene 1988; 74:387-98. [PMID: 3246349 DOI: 10.1016/0378-1119(88)90172-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In Podospora anserina, the phenomenon of senescence was previously shown to be correlated with the presence of a senescence-specific DNA (sen-DNA) resulting from the amplification of some regions (alpha, beta, gamma, epsilon) of the mitochondrial chromosome. The beta region gives rise to sen-DNAs with variable sizes and junctions which share a 1,100-bp common sequence. Here we report the complete nucleotide sequence of one 4-kb beta sen-DNA. Included in the sequence are a large part of the first intron open reading frame (ORF) of the gene ND4L and three short unidentified ORFs more precisely located in the common beta region. The primary structure of the polypeptide possibly encoded by one of them is very similar to the glycine-rich domains present in various single-stranded DNA-binding proteins. The comparison of the information content of this beta sen-DNA with that of other previously sequenced sen-DNAs suggests that the role in the senescence process attributed to the sen-DNAs could be related to the overproduction of a variety of proteins which interact with nucleic acids.
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Affiliation(s)
- C Vierny-Jamet
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, Gif sur Yvette, France
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35
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Extrachromosomal mutants from Podospora anserina: Permanent vegetative growth in spite of multiple recombination events in the mitochondrial genome. ACTA ACUST UNITED AC 1988. [DOI: 10.1007/bf00330614] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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36
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Wolf K, Del Giudice L. The variable mitochondrial genome of ascomycetes: organization, mutational alterations, and expression. ADVANCES IN GENETICS 1988; 25:185-308. [PMID: 3057820 DOI: 10.1016/s0065-2660(08)60460-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- K Wolf
- Institut für Genetik und Mikrobiologie, Universität München, Munich, Federal Republic of Germany
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37
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Smith AG, Pring DR. Nucleotide sequence and molecular characterization of a maize mitochondrial plasmid-like DNA. Curr Genet 1987; 12:617-23. [PMID: 2458851 DOI: 10.1007/bf00368065] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The mitochondrial genome of Black Mexican Sweet maize consists of the principal genome, a 2.3 kb minilinear DNA, a 1,913 bp (1.9 kb) and a 1,445 bp (1.4 kb) minicircular DNA. The three extrachromosomal DNAs exhibit characteristics of autonomous replication in cell suspension culture. The complete sequence of the 1.4 kb minicircle was determined. It has 61 bp of near perfect sequence homology to the 1.9 kb minicircle. Both minicircular DNAs are transcriptionally active; the longest open reading frame of the 1.4 kb minicircle was 231 bp. A putative origin of replication was identified as a high A + T sequence. These minicircles were present in some but not all of 20 maize lines surveyed. None of the lines examined carried the 1.4 kb minicircle without the 1.9 kb minicircle. Nuclear DNA of one line of the seven examined carried homology to both DNAs.
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Affiliation(s)
- A G Smith
- Department of Plant Pathology, University of Florida, Gainesville 32611
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38
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Turker MS, Domenico JM, Cummings DJ. Excision-amplification of mitochondrial DNA during senescence in Podospora anserina. A potential role for an 11 base-pair consensus sequence in the excision process. J Mol Biol 1987; 198:171-85. [PMID: 2448479 DOI: 10.1016/0022-2836(87)90304-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Three novel mitochondrial excision-amplification plasmids of Podospora anserina were identified and the excision-junction sites on the mitochondrial genome determined. All three plasmids were at least partially derived from a common region of the mitochondrial genome termed EcoRI-7 (E7). The entire 5651 base-pair sequence of E7 is presented. Included within this sequence are the E7-specific excision-junction sites of these novel plasmids, the localizations of nine tRNA genes, and the localization of a class I intron of the large rRNA mitochondrial gene. The E7 region contains the 3' portion of this large rRNA gene. Formation of these three novel plasmids as well as other previously described mitochondrial plasmids was found to be associated with the presence of an 11 base-pair consensus sequence, GGCGCAAGCTC, or its complementary sequence. A possible role for this consensus sequence and its complement in plasmid formation and the senescence process of Podospora is discussed. A possible role for the tRNA genes in plasmid formation is considered.
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Affiliation(s)
- M S Turker
- Department of Microbiology/Immunology, University of Colorado Health Sciences Center, Denver 80262
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39
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40
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Turker M, Domenico J, Cummings D. A novel family of mitochondrial plasmids associated with longevity mutants of Podospora anserina. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61646-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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41
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Turker MS, Cummings DJ. Podospora anserina does not senesce when serially passaged in liquid culture. J Bacteriol 1987; 169:454-60. [PMID: 3804968 PMCID: PMC211798 DOI: 10.1128/jb.169.2.454-460.1987] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A procedure was developed for the prolonged growth of the ascomycete fungus Podospora anserina in liquid culture to determine the effects of such growth on the senescence phenotype. Senescence in P. anserina, which is maternally inherited and associated with the excision and amplification of specific mitochondrial plasmids, occurs when this species is grown on solid medium. In two independent experiments no evidence of senescence was observed as mycelia were serially passaged in liquid culture. Further, when separable mycelial masses, termed puff balls, from the liquid cultures were plated on solid medium, a significant increase in their average longevity was observed. The apparent immortality of P. anserina in liquid culture was not dependent upon mitochondrial DNA rearrangements, nor was it affected by the presence of a previously described senescence plasmid, alpha senDNA. Evidence was obtained indicating that growth in liquid culture exerts selective pressure to maintain the wild-type mitochondrial genome.
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42
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Sainsard-Chanet A, Begel O. Transformation of yeast and Podospora: innocuity of senescence-specific DNAs. ACTA ACUST UNITED AC 1986. [DOI: 10.1007/bf00331022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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43
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Despite mtDNA polymorphism the mobile intron (plDNA) of the COI gene is present in ten different races of Podospora anserina. Curr Genet 1985. [DOI: 10.1007/bf00418494] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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44
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Koll F, Belcour L, Vierny C. A 1100-bp sequence of mitochondrial DNA is involved in senescence process in Podospora: study of senescent and mutant cultures. Plasmid 1985; 14:106-17. [PMID: 2999848 DOI: 10.1016/0147-619x(85)90070-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In Podospora, senescence is assumed to be caused by the amplification of short sequences of the mitochondrial genome (sen-DNAs). We have characterized a 1100-bp-long mitochondrial DNA sequence which could be directly involved in the phenomenon. Indeed, by hybridization experiments, we show that this sequence is both present in all the sen-DNA molecules which originate from the beta region of the mitochondrial chromosome and rearranged in the mitochondrial genome of two mitochondrial mutants selected as resistant to senescence.
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45
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Bertrand H, Chan BS, Griffiths AJ. Insertion of a foreign nucleotide sequence into mitochondrial DNA causes senescence in Neurospora intermedia. Cell 1985; 41:877-84. [PMID: 2408762 DOI: 10.1016/s0092-8674(85)80068-4] [Citation(s) in RCA: 124] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The kalilo variants of Neurospora contain a cytoplasmic genetic factor that causes senescence. This factor is a 9.0 kb transposable element (kalDNA) that lacks nucleotide sequence homology with mtDNA and is inserted into the mitochondrial chromosome, often at sites located within the open reading frame in the intron-DNA of the mitochondrial 25S-rRNA gene. Genomes containing the "foreign" DNA insert accumulate during growth, and death occurs as the cells become deficient in functional large and small subunits of mitochondrial ribosomes. The kalDNA transposon may be an "activator" element that causes breaks in mtDNA. Nonsenescing [+] strains of Neurospora do not contain kalDNA.
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46
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Abstract
In the fungus Podospora, a correlation has recently been established between the presence of circular DNA molecules arising from the mitochondrial genome (SEN-DNAs) and the senescence syndrome. Here, I propose a hypothesis which accounts for the initial event which leads to the first SEN-DNA. A molecule in the most frequent situation where the SEN-DNA is an intron which might code for a maturase. This hypothesis is based upon several observations made either in Podospora or in the yeast S. cerevisiae. It assumes that mitochondrially synthesized maturases are unspecific nucleases able to work at the level of RNA and DNA molecules. Their specificity for RNA splicing instead of DNA is given by cytoplasmic proteins. Therefore, if the balance between cytoplasmic and mitochondrial protein syntheses is disturbed in favour of the mitochondrial compartment, the maturase would be accumulated and allowed to splice introns from DNA instead of RNA molecules. This hypothesis can account for aging of higher eucaryotic cells by postulating analogous processes in their nuclear compartment.
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47
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Kück U, Osiewacz HD, Schmidt U, Kappelhoff B, Schulte E, Stahl U, Esser K. The onset of senescence is affected by DNA rearrangements of a discontinuous mitochondrial gene in Podospora anserina. Curr Genet 1985; 9:373-82. [PMID: 2836091 DOI: 10.1007/bf00421608] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mapping and transcription studies have revealed that in Podospora anserina the causative agent of senescence, a mitochondrial plasmid (plDNA), is identical with intron 1 of the discontinuous gene for cytochrome-c-oxidase subunit 1 (COI), which is 2 kpb from the discontinuous gene for cytochrome b (Cytb). A mitochondrial mutant (ex1) devoid of the COI, but not of the Cytb gene provides longevity. A molecular model for the onset of senescence is presented.
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Affiliation(s)
- U Kück
- Lehrstuhl für Allgemeine Botanik, Ruhr-Universität Bochum, Federal Republic of Germany
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48
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49
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Jamet-Vierny C, Begel O, Belcour L. A 20 X 10(3)-base mosaic gene identified on the mitochondrial chromosome of Podospora anserina. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 143:389-94. [PMID: 6468401 DOI: 10.1111/j.1432-1033.1984.tb08385.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
By DNA sequencing and hybridization experiments we have localized the genes cob and col on the mitochondrial chromosome of Podospora anserina. The positions we have determined for these two genes are different from those previously attributed to them. The presence in the gene col of at least two introns, belonging respectively to class I and II, has been demonstrated. This gene, with a size of about 20 X 10(3) bases, appears to be the longest known mitochondrial mosaic gene.
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Kirkwood TB, Holliday R, Rosenberger RF. Stability of the cellular translation process. INTERNATIONAL REVIEW OF CYTOLOGY 1984; 92:93-132. [PMID: 6392136 DOI: 10.1016/s0074-7696(08)61325-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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