Nonself recognition is mediated by HET-C heterocomplex formation during vegetative incompatibility.

Area of Science:

• Mycology
• Cell Biology
• Genetics

Background:

• Filamentous fungi utilize heterokaryon incompatibility (het) loci for nonself recognition during vegetative growth.
• The het-c locus in Neurospora crassa has three allelic specificity groups: het-c(OR), het-c(PA), and het-c(GR).
• Incompatible het-c alleles trigger growth inhibition, reduced conidiation, and hyphal compartmentation and death (HCD).

Purpose of the Study:

• To elucidate the molecular mechanism of nonself recognition mediated by the het-c locus.
• To investigate the role of HET-C protein complex formation and localization in triggering incompatibility responses.

Main Methods:

• Utilized epitope-tagged HET-C protein for detection and localization studies.
• Generated strains with deleted signal peptide sequences in het-c constructs.
• Analyzed heterokaryons and partial diploids with alternative het-c allele specificities.

Main Results:

• Nonself recognition is mediated by a heterocomplex of HET-C polypeptides from alternative specificities.
• The HET-C heterocomplex localizes to the plasma membrane in incompatible interactions.
• Deletion of the signal peptide sequence resulted in cytoplasmic HET-C heterocomplexes and a growth arrest phenotype.

Conclusions:

• The formation and plasma membrane localization of HET-C heterocomplexes are crucial for nonself recognition and subsequent cell death in filamentous fungi.
• This study provides a model for understanding the interplay between recognition mechanisms and cell death pathways.