Two allelic genes responsible for vegetative incompatibility in the fungus Podospora anserina are not essential for cell viability

Turcq, Béatrice; Deleu, Carole; Denayrolles, Muriel; Bégueret, Joël

doi:10.1007/bf00282475

Cited by 74 publications

(55 citation statements)

References 11 publications

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“…A het-s0 ϫ het-s0 cross results in asci with normal numbers of maturing ascospores (Table 1). So it seems that neither het-s nor het-S are essential for ascospore maturation, as already shown by Turcq et al (25). The relatively high percentage of three-spored asci (Table 1) was a recurring feature when analyzing asci from crosses with one or two het-s0 parents.…”

Section: Resultsmentioning

confidence: 71%

“…Segregation distorters are often associated with extensive genomic rearrangements and are often inherited as haplotypes resulting from inhibition of recombination at the distorter locus. It is known that the het-s and het-S loci differ in genomic organization (25) and that all het-s strains contain a transposon long terminal repeat upstream and a 2-kb insertion, respectively, upstream and downstream of the het-s ORF. It was therefore conceivable that spore killing was not due to het-s but due to a closely linked genetic element.…”

Section: Discussionmentioning

confidence: 99%

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Sexual transmission of the [Het-s] prion leads to meiotic drive in Podospora anserina

Dalstra

Swart²,

Debets³

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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In the filamentous fungus Podospora anserina, two phenomena are associated with polymorphism at the het-s locus, vegetative incompatibility and ascospore abortion. Two het-s alleles occur naturally, het-s and het-S. The het-s encoded protein is a prion propagating as a self-perpetuating amyloid aggregate. M eiotic drive is a process mediated by genetic elements, called segregation distorters, that actively bias Mendelian segregation in their favor. In metazoans, classic examples of meiotic drive include the t haplotype in mice and Segregation Distorter (SD) in Drosophila (1). In both these autosomal drive systems, heterozygous males produce gametes of the driver genotype in excess. The molecular mechanisms of meiotic drive remain largely elusive, except in the case of SD in Drosophila, where distortion involves a truncated form of a RanGAP protein and its mislocalization to the nucleus (2). The best studied examples of segregation distortion in fungi are the spore killer systems in the ascomycetes Neurospora crassa (3-6) and Podospora anserina (7). In these haploid organisms, the sexual progeny, the ascospores, are linearly arranged after meiosis. Ascomycetes therefore provide excellent opportunities to investigate the behavior of meiotic drive elements (8). Presence of a killer gene can readily be detected by directly analyzing the pattern of ascospore abortion. Spore killer genes exist as a killer and a sensitive allele or haplotype. In a killer ϫ sensitive cross, the ascospores harboring only the sensitive genotype degenerate. Heterokaryotic spores, containing both a sensitive and a killer nucleus, escape abortion. Both in Neurospora and in Podospora, several spore killer loci have been genetically identified, but so far the mechanism of spore killing is unknown.In 1965, Bernet (9, 10) described properties of the het-s gene in Podospora, now recognized to be analogous to a spore killer locus. The discovery that het-s encodes a prion protein (11, 12) places this observation into a new perspective. The het-s locus, together with at least eight other loci, determines vegetative incompatibility in P. anserina (13,14). Two alleles are found at this locus, termed het-s During the sexual cycle, a single mating-type culture of P. anserina differentiates both male (microconidia) and female (protoperithecia) reproductive structures. The protoperithecium emits a specialized hypha called the trichogyne. Fertilization occurs when a microconidium fuses with a trichogyne of opposite mating type. After migration of the male nucleus down the trichogyne into the female ascogonium, individualized male and female nuclei divide synchronously in a syncytial structure. Because the male gamete contributes very little cytoplasm to this heterokaryon, the cytoplasm of the zygote is essentially of maternal origin. Nuclei of opposite mating type then pair up, and karyogamy takes place in specialized cells. Importantly, at this stage there is a transition from a syncytial to a cellular state (21). Meiotic progeny are linearly arranged as ...

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Section: Resultsmentioning

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Sexual transmission of the [Het-s] prion leads to meiotic drive in Podospora anserina

Dalstra

Swart²,

Debets³

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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“…In ∆het-s, the het-s gene has been inactivated by gene replacement (Turcq et al, 1991). In this strain, the promoter region and the 5′ part of the het-s gene have been deleted and replaced by the ura5 marker.…”

Section: Plasmidsmentioning

confidence: 99%

“…Two distinct alleles of this gene have been described and termed het-s and het-S (Rizet, 1952;Beisson-Schecroun, 1962;Turcq et al, 1990). The hets and het-S alleles encode cytosolic proteins of 289 amino acids that differ by 13 residues and display no homologs of known function in other species (Turcq et al, 1991;Coustou-Linares et al, 2001). The HET-s protein can (unlike HET-S) exist in both a normal form and an infectious prion form (Coustou et al, 1997).…”

mentioning

confidence: 99%

The sequences appended to the amyloid core region of the HET-s prion protein determine higher-order aggregate organization in vivo

Balguerie

Reis

Coulary‐Salin

et al. 2004

Journal of Cell Science

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The [Het-s] prion of the fungus Podospora anserina propagates as a self-perpetuating amyloid form of the HET-s protein. This protein triggers a cell death reaction termed heterokaryon incompatibility when interacting with the HET-S protein, an allelic variant of HET-s. HET-s displays two distinct domains, a N-terminal globular domain and a C-terminal unstructured prion-forming domain (residues 218-289). Here, we describe the characterization of HET-s(157-289), a truncated form of HET-s bearing an extensive deletion in the globular domain but retaining full activity in incompatibility and prion propagation. In vitro, HET-s(157-289) polymerizes into amyloid fibers displaying the same core region as full-length HET-s fibers. We have shown previously that fusions of green fluorescent protein (GFP) with HET-s or HET-s(218-289) form dot-like aggregates in vivo upon transition to the prion state. By contrast, a HET-s(157-289)/GFP fusion protein forms elongated fibrillar aggregates in vivo. Such elongated aggregates can reach up to 150 μm in length. The in vivo dynamics of these organized structures is analysed by time lapse microscopy. We find that the large elongate structures grow by lateral association of shorter fibrillar aggregates. When co-expressed with HET-s(157-289), full-length HET-s and HET-s(218-289) can be incorporated into such elongated aggregates. Together, our data indicate that HET-s(157-289) aggregates can adopt an organized higher-order structure in vivo and that the ability to adopt this supramolecular organization is conferred by the sequences appended to the amyloid core region.

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“…5,6 The HET-s and HET-S allelic variants differ by 13 amino acid residues. 7 Both are 2 domain proteins with an N-terminal folded a-helical domain termed HeLo and a C-terminal natively unfolded domain. 8,9 Prion conversion of HET-s corresponds to folding of the C-terminal region into a specific amyloid b-solenoid fold.…”

Section: Introductionmentioning

confidence: 99%

As a toxin dies a prion comes to life: A tentative natural history of the [Het-s] prion

Daskalov

Saupe

2015

Prion

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A variety of signaling pathways, in particular with roles in cell fate and host defense, operate by a prion-like mechanism consisting in the formation of open-ended oligomeric signaling complexes termed signalosomes. This mechanism emerges as a novel paradigm in signal transduction. Among the proteins forming such signaling complexes are the Nod-like receptors (NLR), involved in innate immunity. It now appears that the [Het-s] fungal prion derives from such a cell-fate defining signaling system controlled by a fungal NLR. What was once considered as an isolated oddity turns out to be related to a conserved and widespread signaling mechanism. Herein, we recall the relation of the [Het-s] prion to the signal transduction pathway controlled by the NWD2 Nod-like receptor, leading to activation of the HET-S pore-forming cell death execution protein. We explicit an evolutionary scenario in which formation of the [Het-s] prion is the result of an exaptation process or how a loss-of-function mutation in a pore-forming cell death execution protein (HET-S) has given birth to a functional prion ([Het-s]).

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Two allelic genes responsible for vegetative incompatibility in the fungus Podospora anserina are not essential for cell viability

Cited by 74 publications

References 11 publications

Sexual transmission of the [Het-s] prion leads to meiotic drive in Podospora anserina

Sexual transmission of the [Het-s] prion leads to meiotic drive in Podospora anserina

The sequences appended to the amyloid core region of the HET-s prion protein determine higher-order aggregate organization in vivo

As a toxin dies a prion comes to life: A tentative natural history of the [Het-s] prion

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