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The Schizosaccharomyces pombe mam1 gene encodes an ABC transporter mediating secretion of M-factor
P U Christensen1, J Davey, O Nielsen
1Department of Genetics, University of Copenhagen, Denmark.
Abstract:
In the fission yeast Schizosaccharomyces pombe, cells of opposite mating type communicate via diffusible peptide pheromones prior to mating. We have cloned the S. pombe mam1 gene, which encodes a 1336-amino acid protein belonging to the ATP-binding cassette (ABC) superfamily. The mam1 gene is only expressed in M cells and the gene product is responsible for the secretion of the mating pheromone. M-factor, a nonapeptide that is S-farnesylated and carboxy-methylated on its C-terminal cysteine residue. The predicted Mam1 protein is highly homologous to mammalian multiple drug-resistance proteins and to the Saccharomyces cerevisiae STE6 gene product, which mediates export of a-factor mating pheromone. We show that STE6 can also mediate secretion of M-factor in S. pombe.
Insights
Researchers identified the fission yeast mam1 gene, crucial for secreting M-factor mating pheromone. This gene product, Mam1, is an ATP-binding cassette transporter similar to proteins in drug resistance and yeast mating. The study shows STE6 can also export M-factor.
Area of Science:
- Cell biology
- Molecular genetics
- Biochemistry
Background:
- Fission yeast (Schizosaccharomyces pombe) cells use diffusible peptide pheromones for communication before mating.
- Understanding pheromone secretion mechanisms is key to studying yeast mating processes.
Purpose of the Study:
- To clone and characterize the S. pombe mam1 gene involved in mating pheromone secretion.
- To investigate the function and homology of the Mam1 protein.
Main Methods:
- Gene cloning and sequencing of the S. pombe mam1 gene.
- Analysis of Mam1 protein homology to known transporters.
- Functional assays to test M-factor secretion mediated by Mam1 and STE6.
Main Results:
- The mam1 gene was cloned and encodes a 1336-amino acid ATP-binding cassette (ABC) superfamily protein.
- Mam1 protein is specifically expressed in M cells and responsible for secreting the S-farnesylated and carboxy-methylated M-factor nonapeptide.
- Mam1 shows high homology to mammalian multidrug resistance proteins and Saccharomyces cerevisiae STE6.
- The study demonstrated that STE6 can also mediate M-factor secretion in S. pombe.
Conclusions:
- The mam1 gene encodes a novel ABC transporter essential for M-factor secretion in S. pombe.
- The functional similarity between Mam1 and STE6 suggests conserved mechanisms for peptide pheromone export in yeast species.
- This research provides insights into the molecular basis of mating pheromone transport in fission yeast.