Heterokaryon incompatibility is a form of programmed cell death in filamentous fungi, triggered by the fusion of filaments from two strains with different sets of het loci. The analyses of the completely sequenced genomes of Aspergillus fumigatus, Aspergillus fischerianus, Aspergillus nidulans and Aspergillus oryzae reveal remarkable diversity of heterokaryon incompatibility systems in aspergilli and other filamentous fungi. The Aspergillus genomes encode numerous homologs of heterokaryon incompatibility proteins from Neurospora crassa and Podospora anserina. Yet the number of homologous proteins, their domain architecture and, perhaps, the underlying mechanisms are quite different. Notable examples include an aspergilli-specific expansion of the putative NACHT NTPases that function as signaling hubs during heterokaryon incompatibility in filamentous fungi, pathogen resistance in plants, or apoptosis in mammals. The Aspergillus NACHT proteins are most similar to GTP-binding protein Het-E and Het-D from P. anserina, but they do not have the HET domain, found at the N-terminus of the Podospora proteins. Instead many of Aspergillus NACHT proteins have a highly divergent nucleoside phosphorylase domain. Still unknown is whether all NATCH NTPases are involved in self/non-self recognition during heterokaryon incompatibility or some are part of another signaling pathway in aspergilli.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)