A Nonself Recognition Gene Complex in Neurospora crassa
Nonself recognition is exemplified in the fungal kingdom by the regulation of cell fusion events between genetically different individuals (heterokaryosis). The het-6 locus is one of approximately 10 loci that control heterokaryon incompatibility during vegetative growth of N. crassa. Previously, it...
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Veröffentlicht in: | Genetics (Austin) 2006-08, Vol.173 (4), p.1991-2004 |
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Sprache: | eng |
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Zusammenfassung: | Nonself recognition is exemplified in the fungal kingdom by the regulation of cell fusion events between genetically different individuals (heterokaryosis). The het-6 locus is one of approximately 10 loci that control heterokaryon incompatibility during vegetative growth of N. crassa. Previously, it was found that het-6-associated incompatibility in Oak Ridge (OR) strains involves two contiguous genes, het-6 and un-24. The OR allele of either gene causes "strong" incompatibility (cell death) when transformed into Panama (PA)-background strains. Several remarkable features of the locus include the nature of these incompatibility genes (het-6 is a member of a repetitive gene family and un-24 also encodes the large subunit of ribonucleotide reductase) and the observation that un-24 and het-6 are in severe linkage disequilibrium. Here, we identify "weak" (slow, aberrant growth) incompatibility activities by un-24PA and het-6PA when transformed separately into OR strains, whereas together they exhibit an additive, strong effect. We synthesized strains with the new allelic combinations un-24PA het-6OR and un-24OR het-6PA, which are not found in nature. These strains grow normally and have distinct nonself recognition capabilities but may have reduced fitness. Comparing the Oak Ridge and Panama het-6 regions revealed a paracentric inversion, the architecture of which provides insights into the evolution of the un-24-het-6 gene complex. |
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ISSN: | 0016-6731 1943-2631 1943-2631 |
DOI: | 10.1534/genetics.106.057562 |