Interaction of the A alpha Y and Z mating-type homeodomain proteins of Schizophyllum commune detected by the two-hybrid system.
The A alpha locus is one of four mating-type loci that control sexual development in Schizophyllum commune. A alpha has nine alternative mating types (A alpha 1-A alpha 9) which encode specific alleles of two homeodomain-related proteins, Y and Z. For example, proteins Y4 and Z4 are encoded by A alpha 4, and Y5 and Z5 are encoded by A alpha 5. Our previous studies showed that A alpha-regulated development is activated in fusion cells between haploid strains by the presence of Y and Z proteins derived from different A alpha mating types (e.g., Y4 and Z5), but not by proteins from the same mating type (e.g., Y4 and Z4). In this study we analyzed protein-protein interactions of Y4 with the Z4 and Z5 isoforms in a two-hybrid system. Protein interactions were detected in filter and liquid assays for beta-galactosidase with Y4 and Z5, a non-self, developmentally active combination, but not with Y4 and Z4, a self, developmentally inactive combination. These results support the hypothesis that non-self combinations of Y and Z form a heteromultimer that activates development, but that self combinations do not. Although developmental target genes directly regulated by the A alpha locus have yet to be identified, it is assumed on the basis of motifs encoded that the Y-Z heteromultimer acts as a transcription factor.
Magae
Y
Y
Forestry and Forest Products Research Institute, Ibaraki, Japan.
Novotny
C
C
Ullrich
R
R
D001483:Base Sequence; D018076:DNA, Complementary; D015966:Gene Expression Regulation, Fungal; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D011485:Protein Binding; D011487:Protein Conformation; D012098:Reproduction; D012567:Schizophyllum / Q000235:genetics* / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D018398:Homeodomain Proteins; D014157:Transcription Factors; C075905:homeodomain protein, Schizophyllum commune