A SUPPRESSOR OF THE HETEROKARYON- INCOMPATIBILITY ASSOCIATED WITH MATING TYPE IN<i>NEUROSPORA CRASSA</i>

Newmeyer, Dorothy

doi:10.1139/g70-115

Cited by 98 publications

(50 citation statements)

References 14 publications

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“…The tol mutant suppresses mating-type-associated heterokaryon incompatibility (54,74). A surprising result of N. crassa genome searches is the number of predicted ORFs with similarity to TOL ( Table 1; included in cluster 9 at http://www.mips.biochem .mpg.de/proj/neurospora/).…”

Section: Downstream Effectors Of Heterokaryon Incompatibilitymentioning

confidence: 99%

Fatal Attraction: Nonself Recognition and Heterokaryon Incompatibility in Filamentous Fungi

2003

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Section: Downstream Effectors Of Heterokaryon Incompatibilitymentioning

confidence: 99%

Fatal Attraction: Nonself Recognition and Heterokaryon Incompatibility in Filamentous Fungi

2003

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“…The tol mutations are recessive and allow mixed mating type heterokaryons or partial diploids to grow vigorously but do not suppress incompatibility triggered by other het loci (54,64). The tol gene has recently been isolated by chromosome walking from the tightly linked trp-4 marker (83).…”

Section: Mating Type-associated Incompatibility and Its Suppressor Tolmentioning

confidence: 99%

Molecular Genetics of Heterokaryon Incompatibility in Filamentous Ascomycetes

Saupe

2000

Microbiol Mol Biol Rev

314

284

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SUMMARY Filamentous fungi spontaneously undergo vegetative cell fusion events within but also between individuals. These cell fusions (anastomoses) lead to cytoplasmic mixing and to the formation of vegetative heterokaryons (i.e., cells containing different nuclear types). The viability of these heterokaryons is genetically controlled by specific loci termed het loci (for heterokaryon incompatibility). Heterokaryotic cells formed between individuals of unlike het genotypes undergo a characteristic cell death reaction or else are severely inhibited in their growth. The biological significance of this phenomenon remains a puzzle. Heterokaryon incompatibility genes have been proposed to represent a vegetative self/nonself recognition system preventing heterokaryon formation between unlike individuals to limit horizontal transfer of cytoplasmic infectious elements. Molecular characterization of het genes and of genes participating in the incompatibility reaction has been achieved for two ascomycetes, Neurospora crassa and Podospora anserina. These analyses have shown that het genes are diverse in sequence and do not belong to a gene family and that at least some of them perform cellular functions in addition to their role in incompatibility. Divergence between the different allelic forms of a het gene is generally extensive, but single-amino-acid differences can be sufficient to trigger incompatibility. In some instances het gene evolution appears to be driven by positive selection, which suggests that the het genes indeed represent recognition systems. However, work on nonallelic incompatibility systems in P. anserina suggests that incompatibility might represent an accidental activation of a cellular system controlling adaptation to starvation.

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“…1). matdependent HI does not require mating-type-specific pheromones or receptor genes but is dependent upon the transcription factor genes mat A-1 and mat a-1 plus tol, a gene which encodes a HET domain-containing protein (41,42,60,74,75). Heterokaryons between strains of the alternative het-6/un-24 haplotype show very severe growth inhibition (56,76); het-6 also encodes a HET domain-containing protein.…”

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VIB-1 Is Required for Expression of Genes Necessary for Programmed Cell Death in Neurospora crassa

2006

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Nonself recognition during somatic growth is an essential and ubiquitous phenomenon in both prokaryotic and eukaryotic species. In filamentous fungi, nonself recognition is also important during vegetative growth. Hyphal fusion between genetically dissimilar individuals results in rejection of heterokaryon formation and in programmed cell death of the fusion compartment. In filamentous fungi, such as Neurospora crassa, nonself recognition and heterokaryon incompatibility (HI) are regulated by genetic differences at het loci. In N. crassa, mutations at the vib-1 locus suppress nonself recognition and HI mediated by genetic differences at het-c/pin-c, mat, and un-24/het-6. vib-1 is a homolog of Saccharomyces cerevisiae NDT80, which is a transcriptional activator of genes during meiosis. For this study, we determined that vib-1 encodes a nuclear protein and showed that VIB-1 localization varies during asexual reproduction and during HI. vib-1 is required for the expression of genes involved in nonself recognition and HI, including pin-c, tol, and het-6; all of these genes encode proteins containing a HET domain. vib-1 is also required for the production of downstream effectors associated with HI, including the production of extracellular proteases upon carbon and nitrogen starvation. Our data support a model in which mechanisms associated with starvation and nonself recognition/HI are interconnected. VIB-1 is a major regulator of responses to nitrogen and carbon starvation and is essential for the expression of genes involved in nonself recognition and death in N. crassa.Nonself recognition during somatic growth is an essential and ubiquitous phenomenon in both prokaryotic and eukaryotic species. In vertebrate species, self/nonself recognition relies on the major histocompatibility complex (MHC), which is an array of polymorphic genetic loci that generate proteins important in pathogen recognition and the activation of defense mechanisms (37). In filamentous fungi, nonself recognition is important during vegetative growth. Hyphal fusion between genetically dissimilar individuals results in rejection of heterokaryon formation and in programmed cell death of the fusion compartment (Fig. 1), an event analogous to nonself recognition following fusion in colonial marine invertebrates, such as Hydractinia and Botryllus (32, 73), and nonself recognition and death following fusion of plasmodia in the slime mold Physarum polycephalum (9). Nonself recognition during heterokaryon formation in filamentous fungi is regulated genetically by het loci (for heterokaryon incompatibility [HI]) (29,70,86). In the filamentous fungus Neurospora crassa, 11 het loci mediate nonself recognition and HI (28, 63); each het locus has two or three alternative allelic specificities. Since these het loci are effectively unlinked, the number of possible het genotypes within a segregating population is at least 2 11 genotypes, thus forming an effective barrier to heterokaryon formation between genetically different isolates. HI in filamentous fungi...

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A SUPPRESSOR OF THE HETEROKARYON- INCOMPATIBILITY ASSOCIATED WITH MATING TYPE INNEUROSPORA CRASSA

Cited by 98 publications

References 14 publications

Fatal Attraction: Nonself Recognition and Heterokaryon Incompatibility in Filamentous Fungi

Fatal Attraction: Nonself Recognition and Heterokaryon Incompatibility in Filamentous Fungi

Molecular Genetics of Heterokaryon Incompatibility in Filamentous Ascomycetes

VIB-1 Is Required for Expression of Genes Necessary for Programmed Cell Death in Neurospora crassa

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