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Distal and proximal actions of peptide pheromone M-factor control different conjugation steps in fission yeast.

Seike T, Nakamura T, Shimoda C - PLoS ONE (2013)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Graduate School of Science, Osaka City University, Osaka, Japan. saysay@sci.osaka-cu.ac.jp

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".

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Induction of sexual agglutination by mating pheromone.(A) Illustration of mating pheromone signaling in S. pombe. The pheromone signal is transmitted through trimeric G-protein α-subunit and the mitogen-activated protein kinase cascade, comprising Byr2, Byr1 and Spk1. The signal transmission pathway is common to both M- and P-cells [22]. (B) The defect in sexual agglutination of the M-factor-less mutant was recovered by exogenously added synthetic M-factor. The homothallic strain FS55 was treated with synthetic M-factor for 4 hr in SSL−N. The agglutination index (AI) was determined for triplicate samples. Means with standard deviations are presented. A portion of each culture was incubated for 24 hr, and the frequency of zygotes was counted. At least 1,000 cells were examined for each sample. (C) Exogenous P-factor addition enhanced constitutive agglutination in a homothallic P-factor-less strain (FS251). At least 500 cells were observed for each sample.
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pone-0069491-g001: Induction of sexual agglutination by mating pheromone.(A) Illustration of mating pheromone signaling in S. pombe. The pheromone signal is transmitted through trimeric G-protein α-subunit and the mitogen-activated protein kinase cascade, comprising Byr2, Byr1 and Spk1. The signal transmission pathway is common to both M- and P-cells [22]. (B) The defect in sexual agglutination of the M-factor-less mutant was recovered by exogenously added synthetic M-factor. The homothallic strain FS55 was treated with synthetic M-factor for 4 hr in SSL−N. The agglutination index (AI) was determined for triplicate samples. Means with standard deviations are presented. A portion of each culture was incubated for 24 hr, and the frequency of zygotes was counted. At least 1,000 cells were examined for each sample. (C) Exogenous P-factor addition enhanced constitutive agglutination in a homothallic P-factor-less strain (FS251). At least 500 cells were observed for each sample.

Mentions: In the fission yeast S. pombe, conjugation is induced between two different mating types, h+ (P) and h– (M) [9–11]. Mating competence is attained by pheromonal communication between cells of the two different mating types. Pheromone signaling in S. pombe is illustrated in Figure 1A. P-cells secrete P-factor, a 23-amino-acid simple peptide, which is recognized by its cognate receptor, Mam2, on the cell surface of M-cells [12]. The mature P-factor peptide is processed from a precursor polypeptide encoded by the gene map2+ [5]. M-cells produce M-factor, a nonapeptide whose C-terminal Cys residue is farnesylated and O-methylated [13,14]. M-factor is recognized by the Map3 receptor on P-cells [15]. Mature M-factor is encoded by triplicate redundant genes: mfm1+, mfm2+, and mfm3+ [13,16]. Precursor proteins synthesized from these mfm genes are processed by as yet unidentified proteolytic enzymes to produce the same nonapeptide. Comprehensive mutagenesis has demonstrated that the primary sequence of the C-terminal half of M-factor is important for recognition by Map3 [17]. Both Mam2 and Map3 are heterotrimeric GTP-binding protein-coupled receptors containing 7 transmembrane domains. Activation of the associated Gα protein (Gpa1) transmits signals through the MAP kinase cascade, comprising Byr2/Ste8 (MAPKKK), Byr1/Ste1 (MAPKK) and Spk1 (MAPK), and finally induces transcription of a set of genes necessary for mating [18].


Distal and proximal actions of peptide pheromone M-factor control different conjugation steps in fission yeast.

Seike T, Nakamura T, Shimoda C - PLoS ONE (2013)

Induction of sexual agglutination by mating pheromone.(A) Illustration of mating pheromone signaling in S. pombe. The pheromone signal is transmitted through trimeric G-protein α-subunit and the mitogen-activated protein kinase cascade, comprising Byr2, Byr1 and Spk1. The signal transmission pathway is common to both M- and P-cells [22]. (B) The defect in sexual agglutination of the M-factor-less mutant was recovered by exogenously added synthetic M-factor. The homothallic strain FS55 was treated with synthetic M-factor for 4 hr in SSL−N. The agglutination index (AI) was determined for triplicate samples. Means with standard deviations are presented. A portion of each culture was incubated for 24 hr, and the frequency of zygotes was counted. At least 1,000 cells were examined for each sample. (C) Exogenous P-factor addition enhanced constitutive agglutination in a homothallic P-factor-less strain (FS251). At least 500 cells were observed for each sample.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3713066&req=5

pone-0069491-g001: Induction of sexual agglutination by mating pheromone.(A) Illustration of mating pheromone signaling in S. pombe. The pheromone signal is transmitted through trimeric G-protein α-subunit and the mitogen-activated protein kinase cascade, comprising Byr2, Byr1 and Spk1. The signal transmission pathway is common to both M- and P-cells [22]. (B) The defect in sexual agglutination of the M-factor-less mutant was recovered by exogenously added synthetic M-factor. The homothallic strain FS55 was treated with synthetic M-factor for 4 hr in SSL−N. The agglutination index (AI) was determined for triplicate samples. Means with standard deviations are presented. A portion of each culture was incubated for 24 hr, and the frequency of zygotes was counted. At least 1,000 cells were examined for each sample. (C) Exogenous P-factor addition enhanced constitutive agglutination in a homothallic P-factor-less strain (FS251). At least 500 cells were observed for each sample.
Mentions: In the fission yeast S. pombe, conjugation is induced between two different mating types, h+ (P) and h– (M) [9–11]. Mating competence is attained by pheromonal communication between cells of the two different mating types. Pheromone signaling in S. pombe is illustrated in Figure 1A. P-cells secrete P-factor, a 23-amino-acid simple peptide, which is recognized by its cognate receptor, Mam2, on the cell surface of M-cells [12]. The mature P-factor peptide is processed from a precursor polypeptide encoded by the gene map2+ [5]. M-cells produce M-factor, a nonapeptide whose C-terminal Cys residue is farnesylated and O-methylated [13,14]. M-factor is recognized by the Map3 receptor on P-cells [15]. Mature M-factor is encoded by triplicate redundant genes: mfm1+, mfm2+, and mfm3+ [13,16]. Precursor proteins synthesized from these mfm genes are processed by as yet unidentified proteolytic enzymes to produce the same nonapeptide. Comprehensive mutagenesis has demonstrated that the primary sequence of the C-terminal half of M-factor is important for recognition by Map3 [17]. Both Mam2 and Map3 are heterotrimeric GTP-binding protein-coupled receptors containing 7 transmembrane domains. Activation of the associated Gα protein (Gpa1) transmits signals through the MAP kinase cascade, comprising Byr2/Ste8 (MAPKKK), Byr1/Ste1 (MAPKK) and Spk1 (MAPK), and finally induces transcription of a set of genes necessary for mating [18].

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Graduate School of Science, Osaka City University, Osaka, Japan. saysay@sci.osaka-cu.ac.jp

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".

Show MeSH
Related in: MedlinePlus