The Aα6 locus: its relation to mating-type regulation of sexual development in Schizophyllum commune

We have isolated and examined the Aα6 mating-type locus of Schizophyllum commune as a first step toward resolving a functional difference between this locus and the Aα loci previously studied. Our analyses show Aα6 to be remarkably similar to the Aα loci of known structure. The locus is composed of two, divergently transcribed genes similar in size to known Z and Y genes of the Aα loci. We have termed the two genes, Z6 and Y6, on the basis of their demonstrated mating activities and encoded protein motifs. The Z6 gene encodes a homeodomain-related sequence, two acidic regions and a predicted coiled-coil motif. The Y6 gene encodes a homeodomain, predicted coiled-coil motif, two regions with homology to the Aβ locus gene V6, a basic region encoding a putative nuclear localization sequence and a serine-rich region. The Z6 and Y6 proteins share these features with the other known Z and Y proteins, respectively. One of the two amino acid sequences with homology to the AβV6 protein has not previously been reported.