Allelic specificity at the het-c heterokaryon incompatibility locus of Neurospora crassa is determined by a highly variable domain.
In filamentous fungi, the ability to form a productive heterokaryon with a genetically dissimilar individual is controlled by specific loci termed het loci. Only strains homozygous for all het loci can establish a heterokaryon. In Neurospora crassa, 11 loci, including the mating-type locus, regulate the capacity to form heterokaryons. An allele of the het-c locus (het-cOR) of N. crassa has been previously characterized and encodes a nonessential 966 amino acid glycine-rich protein. Herein, we describe the genetic and molecular characterization of two hei-c alleles, het-cPA and het-cOR, that have a different specificity from that of het-cOR, showing that vegetative incompatibility is mediated by multiple alleles at het-c. By constructing chimeric alleles, we show that het-c specificity is determined by a highly variable domain of 34-48 amino acids in length. In this regard, het-c is similar to loci that regulate recognition in other species, such as the (S) self-incompatibility locus in plants, the sexual compatibility locus in basidiomycetes and the major histocompatibility complex (MHC) genes in vertebrates.
Saupe
S J
SJ
Botany Department, University of British Columbia, Vancouver, Canada.
Glass
N L
NL
D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic
D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins