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The MID2 gene encodes a putative integral membrane protein with a Ca(2+)-binding domain and shows mating
1Division of Cell Proliferation, National Institute for Basic Biology, Okazaki, Japan.
Abstract:
The MID2 gene whose defect (the mid2-1 mutation) results in mating-pheromone-induced death in Saccharomyces cerevisiae was cloned and its nucleotide (nt) sequence determined. The sequence showed an open reading frame (ORF) coding for a 376-amino-acid (aa) protein with an estimated M(r) of 39,104, and six potential TATA boxes and two pheromone-response elements in its 5'-upstream region. The deduced aa sequence showed that the MID2 product (Mid2p) contains a putative N-terminal signal sequence followed by a long Ser-rich region that could contain O-glycosylation sites, a potential transmembrane domain and a conserved Ca(2+)-binding domain, with the latter two located in the C-terminal half. Northern blot analysis showed that the expression of MID2 is stimulated threefold by mating pheromone. Cells that lack MID2 were able to grow normally, but died when exposed to mating pheromone, like the original mid2-1 mutant.
Insights
The MID2 gene in yeast is crucial for survival when exposed to mating pheromone. Its absence leads to cell death in response to this pheromone signal.
Area of Science:
- Molecular Biology
- Yeast Genetics
Background:
- The MID2 gene is essential for mating pheromone response in Saccharomyces cerevisiae.
- Defects in MID2 (mid2-1 mutation) lead to cell death upon exposure to mating pheromone.
Purpose of the Study:
- To clone and characterize the MID2 gene.
- To understand the molecular basis of mating pheromone-induced death in yeast.
Main Methods:
- Gene cloning and nucleotide sequencing of MID2.
- Analysis of the deduced amino acid sequence of the MID2 product (Mid2p).
- Northern blot analysis to study gene expression.
Main Results:
- The MID2 gene encodes a 376-amino-acid protein (Mid2p) with specific functional domains.
- The 5'-upstream region contains regulatory elements (TATA boxes, pheromone-response elements).
- MID2 expression is upregulated threefold by mating pheromone; its absence causes pheromone-induced death.
Conclusions:
- MID2 plays a critical role in yeast's response to mating pheromone.
- The characterized Mid2p protein structure suggests its function in cellular signaling or response pathways.
- Understanding MID2 function is key to preventing mating pheromone-induced cell death in yeast.