title: Distal and proximal actions of peptide pheromone M-factor control different conjugation steps in fission yeast.
abstract: Mating pheromone signaling is essential for conjugation between haploid cells of P-type (P-cells) and haploid cells of M-type (M-cells) in Schizosaccharomyces pombe. A peptide pheromone, M-factor, produced by M-cells is recognized by the receptor of P-cells. An M-factor-less mutant, in which the M-factor-encoding genes are deleted, is completely sterile. In liquid culture, sexual agglutination was not observed in the mutant, but it could be recovered by adding exogenous synthetic M-factor, which stimulated expression of the P-type-specific cell adhesion protein, Map4. Exogenous M-factor, however, failed to recover the cell fusion defect in the M-factor-less mutant. When M-factor-less cells were added to a mixture of wild-type P- and M-cells, marked cell aggregates were formed. Notably, M-factor-less mutant cells were also incorporated in these aggregates. In this mixed culture, P-cells conjugated preferentially with M-cells secreting M-factor, and rarely with M-factor-less M-cells. The kinetics of mating parameters in liquid culture revealed that polarized growth commenced from the contact region of opposite mating-type cells. Taken together, these findings indicate that M-factor at a low concentration induces adhesin expression, leading to initial cell-cell adhesion in a type of "distal pheromone action", but M-factor that is secreted directly in the proximity of the adhered P-cells may be necessary for cell fusion in a type of "proximal pheromone action".
authors.affiliation: Department of Biology, Graduate School of Science, Osaka City University, Osaka, Japan. saysay@sci.osaka-cu.ac.jp
authors.forename: Taisuke
authors.initials: T
authors.lastname: Seike
authors.forename: Taro
authors.initials: T
authors.lastname: Nakamura
authors.forename: Chikashi
authors.initials: C
authors.lastname: Shimoda
mesh_terms: D015966:Gene Expression Regulation, Fungal; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D010675:Pheromones / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D010455:Peptides; D010675:Pheromones; D029702:Schizosaccharomyces pombe Proteins