Nonself recognition is mediated by HET-C heterocomplex formation during vegetative incompatibility.
Nonself recognition during vegetative growth in filamentous fungi is mediated by heterokaryon incompatibility (het) loci. In Neurospora crassa, het-c is one of 11 het loci. Three allelic specificity groups, termed het-c(OR), het-c(PA) and het-c(GR), exist in natural populations. Heterokaryons or partial diploids that contain het-c alleles of alternative specificity show severe growth inhibition, repression of conidiation and hyphal compartmentation and death (HCD). Using epitope-tagged HET-C, we show that nonself recognition is mediated by the presence of a heterocomplex composed of polypeptides encoded by het-c alleles of alternative specificity. The HET-C heterocomplex localized to the plasma membrane (PM); PM-bound HET-C heterocomplexes occurred in all three het-c incompatible allelic interactions. Strains containing het-c constructs deleted for a predicted signal peptide sequence formed HET-C heterocomplexes in the cytoplasm and showed a growth arrest phenotype. Our finding is a step towards understanding nonself recognition mechanisms that operate during vegetative growth in filamentous fungi, and provides a model for investigating relationships between recognition mechanisms and cell death.
Sarkar
Sovan
S
Plant and Microbial Biology Department, 111 Koshland Hall, University of California, Berkeley, CA 94720, USA.
Iyer
Gopal
G
Wu
Jennifer
J
Glass
N Louise
NL
D000483:Alleles; D000595:Amino Acid Sequence; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D025301:Hyphae / Q000166:cytology / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000166:cytology / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic
D005656:Fungal Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins