The Fungus-Specific HET Domain Mediates Programmed Cell Death in Podospora anserina

ABSTRACT Vegetative incompatibility is a programmed cell death reaction that occurs when fungal cells of unlike genotypes fuse. Genes defining vegetative incompatibility (het genes) are highly polymorphic, and most if not all incompatibility systems include a protein partner bearing the fungus-specific domain termed the HET domain. The nonallelic het-C/het-E incompatibility system is the best-characterized incompatibility system in Podospora anserina. Cell death is triggered by interaction of specific alleles of het-C, encoding a glycolipid transfer protein, and het-E, encoding a HET domain and a WD repeat domain involved in recognition. We show here that overexpression of the isolated HET domain from het-E results in cell death. This cell death is characterized by induction of autophagy, increased vacuolization, septation, and production of lipid droplets, which are hallmarks of cell death by incompatibility. In addition, the HET domain lethality is suppressed by the same mutations as vegetative incompatibility, but not by the inactivation of het-C. These results establish the HET domain as the mediator of cell death by incompatibility and lead to a modular conception of incompatibility systems whereby recognition is ensured by the variable regions of incompatibility proteins and cell death is triggered by the HET domain.

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HET-E and HET-D Belong to a New Subfamily of WD40 Proteins Involved in Vegetative Incompatibility Specificity in the Fungus Podospora anserina

Genetics ◽

10.1093/genetics/161.1.71 ◽

2002 ◽

Vol 161 (1) ◽

pp. 71-81

Author(s):

Eric Espagne ◽

Pascale Balhadère ◽

Marie-Louise Penin ◽

Christian Barreau ◽

Béatrice Turcq

Keyword(s):

Genetic Difference ◽

Podospora Anserina ◽

Wild Type ◽

Incompatible Interaction ◽

Vegetative Incompatibility ◽

Repeat Domain ◽

Upper Face ◽

E1a Gene ◽

Type Strains ◽

Wd40 Repeats

Abstract Vegetative incompatibility, which is very common in filamentous fungi, prevents a viable heterokaryotic cell from being formed by the fusion of filaments from two different wild-type strains. Such incompatibility is always the consequence of at least one genetic difference in specific genes (het genes). In Podospora anserina, alleles of the het-e and het-d loci control heterokaryon viability through genetic interactions with alleles of the unlinked het-c locus. The het-d2Y gene was isolated and shown to have strong similarity with the previously described het-e1A gene. Like the HET-E protein, the HET-D putative protein displayed a GTP-binding domain and seemed to require a minimal number of 11 WD40 repeats to be active in incompatibility. Apart from incompatibility specificity, no other function could be identified by disrupting the het-d gene. Sequence comparison of different het-e alleles suggested that het-e specificity is determined by the sequence of the WD40 repeat domain. In particular, the amino acids present on the upper face of the predicted β-propeller structure defined by this domain may confer the incompatible interaction specificity.

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Cyclophilin D links programmed cell death and organismal aging in Podospora anserina

Aging Cell ◽

10.1111/j.1474-9726.2010.00609.x ◽

2010 ◽

Vol 9 (5) ◽

pp. 761-775 ◽

Cited By ~ 33

Author(s):

Diana Brust ◽

Bertram Daum ◽

Christine Breunig ◽

Andrea Hamann ◽

Werner Kühlbrandt ◽

...

Keyword(s):

Cell Death ◽

Programmed Cell Death ◽

Podospora Anserina ◽

Cyclophilin D

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Mitochondrial quality control in aging and lifespan control of the fungal aging model Podospora anserina

Biochemical Society Transactions ◽

10.1042/bst0391488 ◽

2011 ◽

Vol 39 (5) ◽

pp. 1488-1492 ◽

Cited By ~ 20

Author(s):

Heinz D. Osiewacz

Keyword(s):

Quality Control ◽

Cell Death ◽

Life Cycle ◽

Programmed Cell Death ◽

Podospora Anserina ◽

Molecular Pathways ◽

Mitochondrial Quality Control ◽

Wide Range ◽

Fundamental Process ◽

Hierarchical Manner

Aging of biological systems is a fundamental process controlled by a complex network of molecular pathways. In the filamentous fungus Podospora anserina, a model in which organismal aging can conveniently be analysed, mitochondria play a central role. A wide range of relevant pathways were identified that contribute to the maintenance of a population of functional mitochondria. These pathways act in a hierarchical manner, but all the pathways are limited in capacity. At the end of the life cycle, when the various surveillance pathways are overwhelmed and damage has passed certain thresholds, programmed cell death brings the life of individual P. anserina to an end.

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Inactivation of the Podospora anserina vegetative incompatibility locus het-c, whose product resembles a glycolipid transfer protein, drastically impairs ascospore production.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.91.13.5927 ◽

1994 ◽

Vol 91 (13) ◽

pp. 5927-5931 ◽

Cited By ~ 61

Author(s):

S. Saupe ◽

C. Descamps ◽

B. Turcq ◽

J. Begueret

Keyword(s):

Podospora Anserina ◽

Vegetative Incompatibility ◽

Transfer Protein ◽

Ascospore Production ◽

Incompatibility Locus

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Transcriptome analysis implicates secondary metabolite production, redox reactions, and programmed cell death during allorecognition in Cryphonectria parasitica

G3 Genes|Genome|Genetics ◽

10.1093/g3journal/jkaa021 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Anatoly A Belov ◽

Thomas E Witte ◽

David P Overy ◽

Myron L Smith

Keyword(s):

Cell Death ◽

Programmed Cell Death ◽

Differential Expression ◽

Secondary Metabolite ◽

Transcriptome Analysis ◽

Molecular Mechanisms ◽

Cryphonectria Parasitica ◽

Secondary Metabolite Production ◽

Vegetative Incompatibility ◽

Metabolite Production

Abstract The underlying molecular mechanisms of programmed cell death associated with fungal allorecognition, a form of innate immunity, remain largely unknown. In this study, transcriptome analysis was used to infer mechanisms activated during barrage formation in vic3-incompatible strains of Cryphonectria parasitica, the chestnut blight fungus. Pronounced differential expression occurred in barraging strains of genes involved in mating pheromone (mf2-1, mf2-2), secondary metabolite production, detoxification (including oxidative stress), apoptosis-related, RNA interference, and HET-domain genes. Evidence for secondary metabolite production and reactive oxygen species (ROS) accumulation is supported through UPLC-HRMS analysis and cytological staining, respectively. Differential expression of mating-related genes and HET-domain genes was further examined by RT-qPCR of incompatible interactions involving each of the six vegetative incompatibility (vic) loci in C. parasitica and revealed distinct recognition process networks. We infer that vegetative incompatibility in C. parasitica activates defence reactions that involve secondary metabolism, resulting in increased toxicity of the extra- and intracellular environment. Accumulation of ROS (and other potential toxins) may result in detoxification failure and activation of apoptosis, sporulation, and the expression of associated pheromone genes. The incompatible reaction leaves abundant traces of a process-specific metabolome as conidiation is initiated.

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Using bioinformatic tools to examine similarities between human PDL-1 protein and common tobacco (Nicotiana tabacum).

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.5_suppl.70 ◽

2020 ◽

Vol 38 (5_suppl) ◽

pp. 70-70

Author(s):

Elie G. Dib ◽

Nicholas Hill ◽

Jessica Wollard ◽

Ji Woon Yoo ◽

Joe E. Dib ◽

...

Keyword(s):

Cell Death ◽

Nicotiana Tabacum ◽

Programmed Cell Death ◽

Query Sequence ◽

Alpha Helix ◽

Random Coil ◽

Specific Domain ◽

Bioinformatic Tools ◽

Reading Frames ◽

Novel Protein

70 Background: Human CD274 receptor, known as programmed cell death 1 ligand 1 (RefSeq NP_054862.1), is an inhibitory ligand for Programmed cell death protein 1 (PD1). We aimed in this bioinformatic experiment to identify a homologous PDL-1 protein in plants. Methods: We chose to use tBLASTn because it compares a protein query sequence against a nucleotide sequence database dynamically translated in all six reading frames (both strands). We chose the EST database and restricted our search to plants (Viridiplantae). Results: Using the FASTA sequence of PDL-1 protein, the tBLASTn of the CD274 protein produced a single hit to Nicotiana tabacum (Common tobacco) cDNA, accession number FG181602.1 with E value of 2e-13 and score of 75.9. We translated the FASTA FG181602.1 through ExPASy and after inspecting the results of the 6 open reading frames (ORFs) in comparison with the matching homologous plant protein obtained through tBLASTn above, we found this “novel” protein which we named "PDL1LI". It has the following amino acid sequence: MHAVRRHRGEMHKVALLHNSFLIISILGSYADDFRVMVPTRRLTAARGHSVVLGCEFSPHFGPNPDLSSLVLTWQRQEDSRVVHSFYYERDQLAKQSSAYRNRTALFVTELSKGNASVRIENVGVTDAGRYLCTVSTNQGTNKAELQLDYGAFYTEPRLTINVNSSDVLLQYETEGFPAPVVIWKGEDGENLTDRMKTSVQSNEEMGLYYIKSSYTAPNTPLSLTFTLENHLLHQYLQRPVSYTGGQNSCFYQFIAPVVVS Gor4 shows that our novel PDL1LI protein is 181 amino acids long with 36% alpha helix, 18% extended strand and 46% random coil sequence. According to BLASTp, this protein contains an immunoglobulin domain found in the Ig superfamily in the first half of the protein, and specific domain hits to the Ig_HHLA2, V-set, and IGv domains, with e-values of 1.37e-28, 2.23e-08, and 1.73e-06. Conclusions: Of all the plants, we found a single homology for our original protein PDL1 only in Nicotiana tabacum. We named this novel protein PDL1LI. Tobacco has been implicated in the etiology of several cancers including lung cancer, bladder cancer, head and neck cancers, etc. A wet lab experiment is underway to isolate our novel protein PDL1LI and to study its properties including any possible inhibitory actions on T cells. If confirmed, then we would have elucidated a new carcinogenic mechanism of tobacco.

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