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Horizontal transfer of tRNA genes to mitochondrial plasmids facilitates gene loss from fungal mitochondrial DNA. Curr Genet 2023; 69:55-65. [PMID: 36447017 PMCID: PMC9925561 DOI: 10.1007/s00294-022-01259-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/09/2022] [Accepted: 11/12/2022] [Indexed: 12/05/2022]
Abstract
Fungal and plant mitochondria are known to exchange DNA with retroviral plasmids. Transfer of plasmid DNA to the organellar genome is best known and occurs through wholesale insertion of the plasmid. Less well known is the transfer of organellar DNA to plasmids, in particular tRNA genes. Presently, it is unknown whether fungal plasmids can adopt mitochondrial functions such as tRNA production through horizontal gene transfer. In this paper, we studied the exchange of DNA between fungal linear plasmids and fungal mtDNA, mainly focusing on the basidiomycete family Lyophyllaceae. We report at least six independent transfers of complete tRNA genes to fungal plasmids. Furthermore, we discovered two independent cases of loss of a tRNA gene from a fungal mitochondrial genome following transfer of such a gene to a linear mitochondrial plasmid. We propose that loss of a tRNA gene from mtDNA following its transfer to a plasmid creates a mutualistic dependency of the host mtDNA on the plasmid. We also find that tRNA genes transferred to plasmids encode codons that occur at the lowest frequency in the host mitochondrial genomes, possibly due to a higher number of unused transcripts. We discuss the potential consequences of mtDNA transfer to plasmids for both the host mtDNA and the plasmid.
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2
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Hamann A, Osiewacz HD. To die or not to die - How mitochondrial processes affect lifespan of Podospora anserina. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148568. [PMID: 35533726 DOI: 10.1016/j.bbabio.2022.148568] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/12/2022] [Accepted: 05/02/2022] [Indexed: 12/22/2022]
Abstract
The filamentous ascomycete Podospora anserina is a well-established model system to study organismic aging. Its senescence syndrome has been investigated for more than fifty years and turned out to have a strong mitochondrial etiology. Several different mitochondrial pathways were demonstrated to affect aging and lifespan. Here, we present an update of the literature focusing on the cooperative interplay between different processes.
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Affiliation(s)
- Andrea Hamann
- Institute of Molecular Biosciences, J. W. Goethe University, Frankfurt am Main, Germany.
| | - Heinz D Osiewacz
- Institute of Molecular Biosciences, J. W. Goethe University, Frankfurt am Main, Germany.
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3
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Benocci T, de Vries RP, Daly P. A senescence-delaying pre-culture medium for transcriptomics of Podospora anserina. J Microbiol Methods 2018; 146:33-36. [DOI: 10.1016/j.mimet.2018.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 01/18/2018] [Accepted: 01/18/2018] [Indexed: 01/15/2023]
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4
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Leiter É, Park HS, Kwon NJ, Han KH, Emri T, Oláh V, Mészáros I, Dienes B, Vincze J, Csernoch L, Yu JH, Pócsi I. Characterization of the aodA, dnmA, mnSOD and pimA genes in Aspergillus nidulans. Sci Rep 2016; 6:20523. [PMID: 26846452 PMCID: PMC4742808 DOI: 10.1038/srep20523] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 01/05/2016] [Indexed: 01/02/2023] Open
Abstract
Mitochondria play key roles in cellular energy generation and lifespan of most eukaryotes. To understand the functions of four nuclear-encoded genes predicted to be related to the maintenance of mitochondrial morphology and function in Aspergillus nidulans, systematic characterization was carried out. The deletion and overexpression mutants of aodA, dnmA, mnSOD and pimA encoding alternative oxidase, dynamin related protein, manganese superoxide dismutase and Lon protease, respectively, were generated and examined for their growth, stress tolerances, respiration, autolysis, cell death, sterigmatocystin production, hyphal morphology and size, and mitochondrial superoxide production as well as development. Overall, genetic manipulation of these genes had less effect on cellular physiology and ageing in A. nidulans than that of their homologs in another fungus Podospora anserina with a well-characterized senescence. The observed interspecial phenotypic differences can be explained by the dissimilar intrinsic stabilities of the mitochondrial genomes in A. nidulans and P. anserina. Furthermore, the marginally altered phenotypes observed in A. nidulans mutants indicate the presence of effective compensatory mechanisms for the complex networks of mitochondrial defense and quality control. Importantly, these findings can be useful for developing novel platforms for heterologous protein production, or on new biocontrol and bioremediation technologies based on Aspergillus species.
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Affiliation(s)
- Éva Leiter
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Hee-Soo Park
- Departments of Bacteriology and Genetics, The University of Wisconsin-Madison, Wisconsin, USA
| | - Nak-Jung Kwon
- Departments of Bacteriology and Genetics, The University of Wisconsin-Madison, Wisconsin, USA
| | - Kap-Hoon Han
- Departments of Bacteriology and Genetics, The University of Wisconsin-Madison, Wisconsin, USA.,Department of Pharmaceutical Engineering, Woosuk University, Wanju, Republic of Korea
| | - Tamás Emri
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Viktor Oláh
- Department of Botany, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Ilona Mészáros
- Department of Botany, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Vincze
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jae-Hyuk Yu
- Departments of Bacteriology and Genetics, The University of Wisconsin-Madison, Wisconsin, USA
| | - István Pócsi
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
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5
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van Diepeningen AD, Engelmoer DJP, Sellem CH, Huberts DHEW, Slakhorst SM, Sainsard-Chanet A, Zwaan BJ, Hoekstra RF, Debets AJM. Does autophagy mediate age-dependent effect of dietary restriction responses in the filamentous fungus Podospora anserina? Philos Trans R Soc Lond B Biol Sci 2015; 369:20130447. [PMID: 24864315 DOI: 10.1098/rstb.2013.0447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Autophagy is a well-conserved catabolic process, involving the degradation of a cell's own components through the lysosomal/vacuolar machinery. Autophagy is typically induced by nutrient starvation and has a role in nutrient recycling, cellular differentiation, degradation and programmed cell death. Another common response in eukaryotes is the extension of lifespan through dietary restriction (DR). We studied a link between DR and autophagy in the filamentous fungus Podospora anserina, a multicellular model organism for ageing studies and mitochondrial deterioration. While both carbon and nitrogen restriction extends lifespan in P. anserina, the size of the effect varied with the amount and type of restricted nutrient. Natural genetic variation for the DR response exists. Whereas a switch to carbon restriction up to halfway through the lifetime resulted in extreme lifespan extension for wild-type P. anserina, all autophagy-deficient strains had a shorter time window in which ageing could be delayed by DR. Under nitrogen limitation, only PaAtg1 and PaAtg8 mediate the effect of lifespan extension; the other autophagy-deficient mutants PaPspA and PaUth1 had a similar response as wild-type. Our results thus show that the ageing process impinges on the DR response and that this at least in part involves the genetic regulation of autophagy.
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Affiliation(s)
- Anne D van Diepeningen
- Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Daniël J P Engelmoer
- Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands Department of Ecological Sciences, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Carole H Sellem
- Centre de Génétique Moléculaire, CNRS, UPR2167, 91198 Gif-sur-Yvette, France
| | - Daphne H E W Huberts
- Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - S Marijke Slakhorst
- Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Annie Sainsard-Chanet
- Centre de Génétique Moléculaire, CNRS, UPR2167, 91198 Gif-sur-Yvette, France Université Paris-Sud, 91405 Orsay, France
| | - Bas J Zwaan
- Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Rolf F Hoekstra
- Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Alfons J M Debets
- Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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6
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Geydan TD, Debets AJM, Verkley GJM, van Diepeningen AD. Correlated evolution of senescence and ephemeral substrate use in the Sordariomycetes. Mol Ecol 2012; 21:2816-28. [PMID: 22486972 DOI: 10.1111/j.1365-294x.2012.05569.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Evolutionary theory predicts that senescence--a decline in reproduction and survival with increasing age--can evolve as a trade-off between investment in reproduction on one side and in somatic maintenance and repair on the other. The ecology of a species is crucial because it provides the external causes of death that determine the statistical limit to a species' lifespan. Filamentous fungi are generally believed to be nonsenescent, and there are indeed spectacular examples of very old fungal individuals in nature. However, some fungi utilize ephemeral resources, and therefore, senescence is expected to have evolved, like in the coprophilic Podospora anserina, the only well-studied filamentous fungus with intrinsic senescence. Here, we hypothesize that rapid senescence is more common in fungi than generally believed and that the phylogenetic distribution of senescence correlates with ecology. We collected lifespan data for a set of Sordariomycetes and constructed phylogenies based on several nuclear sequences. Several of the strains were from the CBS culture collection, originally isolated from various substrates, some of which ephemeral. In addition, we isolated new strains from short-lived substrates. Senescence was observed throughout the phylogeny. Correlation tests support the hypothesis that in the Sordariomycetes, senescence is a trait that has arisen in response to ephemeral substrates, and that it has evolved repeatedly and independently along the phylogeny.
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Affiliation(s)
- Thomas D Geydan
- Department of Genetics, Plant Sciences Group, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, the Netherlands
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7
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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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8
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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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9
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van Diepeningen AD, Maas MFPM, Huberts DHEW, Goedbloed DJ, Engelmoer DJP, Slakhorst SM, Koopmanschap AB, Krause F, Dencher NA, Sellem CH, Sainsard-Chanet A, Hoekstra RF, Debets AJM. Calorie restriction causes healthy life span extension in the filamentous fungus Podospora anserina. Mech Ageing Dev 2009; 131:60-8. [PMID: 20026344 DOI: 10.1016/j.mad.2009.12.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Revised: 11/13/2009] [Accepted: 12/14/2009] [Indexed: 12/17/2022]
Abstract
Although most fungi appear to be immortal, some show systemic senescence within a distinct time frame. Podospora anserina for example shows an irreversible growth arrest within weeks of culturing associated with a destabilization of the mitochondrial genome. Here, we show that calorie restriction (CR), a regimen of under-nutrition without malnutrition, increases not only life span but also forestalls the aging-related decline in fertility. Similar to respiratory chain deficiencies the life span extension is associated with lower levels of intracellular H(2)O(2) measurements and a stabilization of the mitochondrial genome. Unlike respiratory chain deficiencies, CR cultures have a wild-type-like OXPHOS machinery similar to that of well-fed cultures as shown by native electrophoresis of mitochondrial protein complexes. Together, these data indicate that life span extension via CR is fundamentally different from that via respiratory chain mutations: Whereas the latter can be seen as a pathology, the former promotes healthy life span extension and may be an adaptive response.
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Affiliation(s)
- Anne D van Diepeningen
- Laboratory of Genetics, Department of Plant Sciences, Wageningen University, Arboretumlaan 4, 6703BD Wageningen, The Netherlands.
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10
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Mutations in two zinc-cluster proteins activate alternative respiratory and gluconeogenic pathways and restore senescence in long-lived respiratory mutants of Podospora anserina. Genetics 2009; 182:69-78. [PMID: 19255367 DOI: 10.1534/genetics.109.100834] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Podospora anserina, inactivation of the respiratory chain results in a spectacular life-span extension. This inactivation is accompanied by the induction of the alternative oxidase. Although the functional value of this response is evident, the mechanism behind it is far from understood. By screening suppressors able to reduce the life-span extension of cytochrome-deficient mutants, we identified mutations in two zinc-cluster proteins, RSE2 and RSE3, which are conserved in other ascomycetes. These mutations led to the overexpression of the genes encoding the alternative oxidase and the gluconeogenic enzymes, fructose-1, 6 biphosphatase, and pyruvate carboxykinase. Both RSE2 and RSE3 are required for the expression of these genes. We also show that, even in the absence of a respiratory deficiency, the wild-type RSE2 and RSE3 transcription factors are involved in life-span control and their inactivation retards aging. These data are discussed with respect to aging, the regulation of the alternative oxidase, and carbon metabolism.
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11
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The mitochondrial genome of the phytopathogenic basidiomycete Moniliophthora perniciosa is 109kb in size and contains a stable integrated plasmid. ACTA ACUST UNITED AC 2008; 112:1136-52. [DOI: 10.1016/j.mycres.2008.04.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 03/19/2008] [Accepted: 04/24/2008] [Indexed: 11/17/2022]
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Life span extension by dietary restriction is reduced but not abolished by loss of both SIR2 and HST2 in Podospora anserina. Mech Ageing Dev 2008; 129:714-21. [PMID: 18930755 DOI: 10.1016/j.mad.2008.09.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 08/22/2008] [Accepted: 09/08/2008] [Indexed: 11/22/2022]
Abstract
Dietary restriction (DR) extends life span of many organisms, from yeast to mammals. The question of whether or not the SIR2 protein functions to mediate life span extension in response to DR remains debated. In this paper, we studied the relationship between SIR2 and DR in the filamentous fungus Podospora anserina. We show that the loss of PaSir2, PaHst2 or PaPnc1 does not alter life span under standard conditions. PaHst2 is the closest paralog of PaSir2 and the ortholog of yeast HST2 and PaPnc1 is the ortholog of the yeast PNC1 which encodes a nicotinamidase that deaminates nicotinamide, a natural inhibitor of SIR2. As observed for other organisms, overexpression of PaSir2 weakly increases life span under standard condition. Under DR conditions, deletion of the PaSir2 or PaHst2 genes induce a significant reduction in life span extension, while the double mutant strongly reduces life span extension. However, a clear response to DR subsists in the double mutant, demonstrating that DR acts through a SIR2/HST2 independent pathway.
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van Diepeningen AD, Debets AJM, Slakhorst SM, Hoekstra RF. Mitochondrial pAL2-1 plasmid homologs are senescence factors inPodospora anserina independent of intrinsic senescence. Biotechnol J 2008; 3:791-802. [DOI: 10.1002/biot.200800005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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14
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Hamann A, Brust D, Osiewacz HD. Apoptosis pathways in fungal growth, development and ageing. Trends Microbiol 2008; 16:276-83. [PMID: 18440231 DOI: 10.1016/j.tim.2008.03.003] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 02/22/2008] [Accepted: 03/26/2008] [Indexed: 10/22/2022]
Abstract
Apoptosis is one type of programmed cell death with great importance for development and homeostasis of multicellular organisms. Unexpectedly, during the past decade, evidence has been obtained for the existence of a basal apoptosis machinery in yeast, as unicellular fungus, and in some filamentous fungi, a group of microorganisms that are neither true unicellular nor true multicellular biological systems but something in between. Here, we review evidence for a role of apoptotic processes in fungal pathogenicity, competitiveness, propagation, ageing and lifespan control.
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Affiliation(s)
- Andrea Hamann
- Institute for Molecular Biosciences, Department of Biosciences and Cluster of Excellence Macromolecular Complexes, J.W. Goethe-University, Max-von-Laue-Strasse 9, Frankfurt, Germany
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15
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Abstract
Plant mitochondria contain small extrachromosomal DNAs in addition to a large and complex main mitochondrial genome. These molecules can be regarded as extrachromosomal replicons or plasmids, of which there are two forms, circular and linear. Linear mitochondrial plasmids are present in many fungi and in some plants, but they seem to be absent from most animal cells. They usually have a common structural feature, called an invertron, that is characterized by the presence of terminal inverted repeats and proteins covalently attached to their 5 termini. Linear mitochondrial plasmids possess one to six ORFs that can encode unknown proteins but often code for the DNA and RNA polymerases. Although the functions of most linear plasmids in plant mitochondria are unknown, some plasmids may be associated with mitochondrial genome rearrangements and may have phenotypic effects due to their integration into mitochondrial genome. The Brassica 11.6-kb plasmid, one of the linear mitochondrial plasmids in plants, shows a non-maternal inheritance, in contrast to mitochondrial genomes. The origin of these plasmids is still a mystery, but indirect evidence indicates the possibility of horizontal transfer from fungal mitochondria. In this review, the main features of these unique DNAs present in plant mitochondria are described.
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Maas MFPM, Sellem CH, Hoekstra RF, Debets AJM, Sainsard-Chanet A. Integration of a pAL2-1 homologous mitochondrial plasmid associated with life span extension in Podospora anserina. Fungal Genet Biol 2007; 44:659-71. [PMID: 17166751 DOI: 10.1016/j.fgb.2006.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 09/29/2006] [Accepted: 10/27/2006] [Indexed: 11/16/2022]
Abstract
We isolated and characterized a novel spontaneous longevity mutant of Podospora anserina strain Wa32 carrying one of the pAL2-1 homologous mitochondrial plasmids. This mutant is at least ten fold longer-lived than the wild type, and is hence a formal suppressor of both the regular and the 'plasmid-based' senescence process. We show that the longevity trait is maternally inherited and coincides with the presence of a copy of the plasmid integrated in the 5' UTR of the mitochondrial Complex I genes nd2 and nd3. This mutation is associated with complex alterations in the respiratory chain, including a dispensable induction of the alternative oxidase. It is also associated with a stabilization of the mitochondrial chromosome and a reduction of the overall cellular level of reactive oxygen species.
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Affiliation(s)
- M F P M Maas
- CNRS, Centre de Génétique Moléculaire, 1 Avenue de la terrasse, 91198 Gif-sur-Yvette cedex, France.
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17
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Maas MFPM, Hoekstra RF, Debets AJM. A mitochondrial mutator plasmid that causes senescence under dietary restricted conditions. BMC Genet 2007; 8:9. [PMID: 17407571 PMCID: PMC1864894 DOI: 10.1186/1471-2156-8-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Accepted: 04/02/2007] [Indexed: 11/25/2022] Open
Abstract
Background Calorie or dietary restriction extends life span in a wide range of organisms including the filamentous fungus Podospora anserina. Under dietary restricted conditions, P. anserina isolates are several-fold longer lived. This is however not the case in isolates that carry one of the pAL2-1 homologous mitochondrial plasmids. Results We show that the pAL2-1 homologues act as 'insertional mutators' of the mitochondrial genome, which may explain their negative effect on life span extension. Sequencing revealed at least fourteen unique plasmid integration sites, of which twelve were located within the mitochondrial genome and two within copies of the plasmid itself. The plasmids were able to integrate in their entirety, via a non-homologous mode of recombination. Some of the integrated plasmid copies were truncated, which probably resulted from secondary, post-integrative, recombination processes. Integration sites were predominantly located within and surrounding the region containing the mitochondrial rDNA loci. Conclusion We propose a model for the mechanism of integration, based on innate modes of mtDNA recombination, and discuss its possible link with the plasmid's negative effect on dietary restriction mediated life span extension.
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Affiliation(s)
- Marc FPM Maas
- Centre de Génétique Moléculaire, Centre Nationale de la Recherche Scientifique, 1 Avenue de la Terrasse, Gif-sur-Yvette, France
- Laboratorium voor Erfelijkheidsleer, Wageningen Universiteit, Arboretumlaan 4, Wageningen, The Netherlands
| | - Rolf F Hoekstra
- Laboratorium voor Erfelijkheidsleer, Wageningen Universiteit, Arboretumlaan 4, Wageningen, The Netherlands
| | - Alfons JM Debets
- Laboratorium voor Erfelijkheidsleer, Wageningen Universiteit, Arboretumlaan 4, Wageningen, The Netherlands
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18
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Maas MFPM, Hoekstra RF, Debets AJM. Hybrid mitochondrial plasmids from senescence suppressor isolates of Neurospora intermedia. Genetics 2007; 175:785-94. [PMID: 17151255 PMCID: PMC1800619 DOI: 10.1534/genetics.106.063081] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Accepted: 11/14/2006] [Indexed: 11/18/2022] Open
Abstract
We analyzed several natural suppressor isolates of the pKalilo-based fungal senescence syndrome of Neurospora intermedia. The pKalilo plasmid did not increase in titer in these isolates. Nor did it show integration "de novo." In at least two of the senescence suppressor isolates, pKalilo had formed stable recombinants with other mitochondrial elements. pKalilo/mtDNA recombination junctions were complete and appeared to have been formed via a nonhomologous recombination mechanism. Further analysis revealed that pKalilo had recombined a novel, 2.6-kb cryptic mitochondrial retroplasmid, similar to the mitochondrial retroplasmid pTHR1 from Trichoderma harzianum and retroplasmids of the "Varkud" homology group. The recombinant molecules consisted of pKalilo, the novel element, and short intervening stretches of mtDNA. The latter stretches clearly corresponded to "in vivo" mitochondrial cDNA, suggesting that the molecules had formed via the action of a template-switching reverse transcriptase. We discuss how different types of mitochondrial plasmids interact and how their detrimental effect on the host may be suppressed.
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Affiliation(s)
- M F P M Maas
- Centre de Génétique Moléculaire, CNRS, 91198 Gif-sur-Yvette Cedex, France.
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Lorin S, Dufour E, Sainsard-Chanet A. Mitochondrial metabolism and aging in the filamentous fungus Podospora anserina. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:604-10. [PMID: 16624249 DOI: 10.1016/j.bbabio.2006.03.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 03/06/2006] [Accepted: 03/07/2006] [Indexed: 11/18/2022]
Abstract
The filamentous fungus Podospora anserina has a limited lifespan. In this organism, aging is systematically associated to mitochondrial DNA instability. We recently provided evidence that the respiratory function is a key determinant of its lifespan. Loss of function of the cytochrome pathway leads to the compensatory induction of an alternative oxidase, to a decreased production of reactive oxygen species and to a striking increase in lifespan. These changes are associated to the stabilization of the mitochondrial DNA. Here we review and discuss the links between these different parameters and their implication in the control of lifespan. Since we demonstrated the central role of mitochondrial metabolism in aging, the same relationship has been evidenced in several model systems from yeast to mice, confirming the usefulness of simple organisms as P. anserina for studying lifespan regulation.
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Affiliation(s)
- Séverine Lorin
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette Cedex, France
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Scheckhuber C. MiMage: A Pan-European Project on the Role of Mitochondria in Aging. ACTA ACUST UNITED AC 2005; 2005:pe14. [DOI: 10.1126/sageke.2005.20.pe14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Cahan P, Kennell JC. Identification and distribution of sequences having similarity to mitochondrial plasmids in mitochondrial genomes of filamentous fungi. Mol Genet Genomics 2005; 273:462-73. [PMID: 15891911 DOI: 10.1007/s00438-005-1133-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 02/18/2005] [Indexed: 11/30/2022]
Abstract
Mitochondrial plasmids are autonomously replicating genetic elements commonly associated with fungal and plant species. Analysis of several plant and fungal mitochondrial genomes has revealed regions that show significant homology to mitochondrial plasmids, suggesting that plasmids have had a long-term association with their mitochondrial hosts. To assess the degree to which plasmids have invaded fungal mitochondrial genomes, BLAST search parameters were modified to identify plasmid sequences within highly AT-rich mtDNAs, and output data were parsed by E value, score, and sequence complexity. High scoring hits were evaluated for the presence of shared repetitive elements and location within plasmids and mtDNAs. Our searches revealed multiple sites of sequence similarity to four distinct plasmids in the wild-type mtDNA of Neurospora crassa, which collectively comprise more than 2% of the mitochondrial genome. Regions of plasmid similarity were not restricted to plasmids known to be associated with senescence, indicating that all mt plasmids can potentially integrate into mitochondrial DNA. Unexpectedly, plasmid-related sequences were found to be clustered in regions that have disproportionately low numbers of PstI palindromic sequences, suggesting that these repetitive elements may play a role in eliminating foreign DNA. A separate class of GC-rich palindromes was identified that appear to be mobile, as indicated by their occurrence within regions of plasmid homology. Sites of sequence similarity to mitochondrial plasmids were also detected in other filamentous fungi, but to a lesser degree. The tools developed here will be useful in assessing the contribution plasmids have made to mitochondrial function and in understanding the co-evolution of mitochondrial plasmids and their hosts.
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Affiliation(s)
- Patrick Cahan
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA
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Maas MFPM, van Mourik A, Hoekstra RF, Debets AJM. Polymorphism for pKALILO based senescence in Hawaiian populations of Neurospora intermedia and Neurospora tetrasperma. Fungal Genet Biol 2005; 42:224-32. [PMID: 15707843 DOI: 10.1016/j.fgb.2004.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2004] [Revised: 11/11/2004] [Accepted: 11/14/2004] [Indexed: 10/26/2022]
Abstract
The natural population of Neurospora intermedia from Hawaii is polymorphic for the presence of the linear mitochondrial plasmid pKALILO that is associated with an infectious senescence syndrome. Although inter-specific horizontal transmission is experimentally possible, thus far pKALILO associated senescence has never been found outside N. intermedia in nature. Here, we demonstrate that it is not limited to the natural population of the heterothallic species N. intermedia, but also present in the sympatric population of its close relative, the pseudo-homothallic species Neurospora tetrasperma. We did a comparative analysis of the hallmarks of senescence in both species and show that: (1) Senescence is contagious in both species: the senescent state is efficiently transmitted between vegetatively compatible isolates. (2) All senescent isolates from both species contain the autonomously replicating linear mitochondrial senescence plasmid pKALILO. (3) In both species, senescent cultures contained copies of pKALILO inserted into the mitochondrial genome. Two of these inserts were characterized using semi-random two-step PCR, and were located within the large subunit mitochondrial rRNA gene. (4) However, pKALILO was less frequent in N. tetrasperma than in N. intermedia. (5) Also, the onset of senescence was significantly delayed in N. tetrasperma, compared to that in N. intermedia. We hypothesize how these differences in frequency and effect of pKALILO are connected to the respective life histories of their hosts.
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Affiliation(s)
- Marc F P M Maas
- Laboratory of Genetics, Department of Plant Sciences, Wageningen University, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands.
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