Changes in Mate Recognition Through Alterations of Pheromones and Receptors in the Multisexual Mushroom Fungus Schizophyllum commune

Abstract

Schizophyllum commune has thousands of mating types defined in part by numerous lipopeptide pheromones and their G-protein-coupled receptors. These molecules are encoded within multiple versions of two redundantly functioning B mating-type loci, Bα and Bβ. Compatible combinations of pheromones and receptors, produced by individuals of different B mating types, trigger a pathway of fertilization required for sexual development. Analysis of the Bβ2 mating-type locus revealed a large cluster of genes encoding a single pheromone receptor and eight different pheromones. Phenotypic effects of mutations within these genes indicated that small changes in both types of molecules could significantly alter their specificity of interaction. For example, a conservative amino acid substitution in a pheromone resulted in a gain of function toward one receptor and a loss of function with another. A two-amino-acid deletion from a receptor precluded the mutant pheromone from activating the mutant receptor, yet this receptor was activated by other pheromones. Sequence comparisons provided clues toward understanding how so many variants of these multigenic loci could have evolved through duplication and mutational divergence. A three-step model for the origin of new variants comparable to those found in nature is presented.

A constitutively active GPCR governs morphogenic transitions in Cryptococcus neoformans

“…To be self-compatible at the pheromone/pheromone receptor locus, the receptors are either activated by an autocrine signalling loop or constitutively active, locking the pheromone signalling pathway in the 'on' state. In the laboratory, examples of mutations that alter pheromone receptors to recognize pheromone produced by the same locus have been reported, as well as mutations that lead to constitutive receptor activity (Fowler et al, 2001). For example, in C. cinerea, an R96H mutation in TM3 enables receptor activation in response to pheromone encoded by the same locus and a Q229P mutation in TM6 of another receptor caused constitutive activity (Olesnicky et al, 1999(Olesnicky et al, , 2000.…”

Homeodomain 1 Genes of the Different HD Subloci of Flammulina velutipes Can Activate the HD Pathway and Are Involved in Mating, Clamp Cell Formation, and Upregulation of FvClp1

“…This gene is homologous to the Clp1 gene that controls pincer formation in C. cinerea. , Therefore, the correlation between HD locus and the FvClp1 gene in F. velutipes is worthy of attention.…”

“…This gene is homologous to the Clp1 gene that controls pincer formation in C. cinerea. 26,28 Therefore, the correlation between HD locus and the FvClp1 gene in F. velutipes is worthy of attention. For this reason, we cloned two separate FvHd1 genes, one from each of the HD subloci, and determined their function in the activation of the HD pathway.…”

Nuclear-Localized Fluorescent Proteins Enable Visualization of Nuclear Behavior in the Basidiomycete Schizophyllum commune Early Mating Interactions

“…In S. commune the hyphal fusions initiating the mating occur regardless of mating-type genes [3,11]. The pheromone-receptor interaction takes place after the fusion, intracellularly, and is dependent on the invading pheromone [28]. The relationship between the A and B mating-type genes has not been analyzed in tetrapolar filamentous fungi, but in the compatible mating (A = B =), not only the number of yellow nuclei was high but also the total number of nuclei (Table 2).…”