A transcriptional cascade governs entry into meiosis in Saccharomyces cerevisiae.
Two signals activate meiosis in yeast: starvation and expression of the a1 and alpha 2 products of the mating-type locus. Prior studies suggest that these signals stimulate expression of an activator of meiosis, the IME1 (inducer of meiosis) product. We have cloned a gene, IME2, with properties similar to those of IME1: both genes are required for meiosis, and both RNAs are induced in meiotic cells. Elevated dosage of IME1 or IME2 stimulates the meiotic recombination pathway without starvation; thus, the IME products may be part of the switch that activates meiosis. IME1 was found to be required for IME2 expression, and a multicopy IME2 plasmid permitted meiosis in an ime1 deletion mutant. Accordingly, we propose that the IME1 product stimulates meiosis mainly through activation of IME2 expression.
Smith
H E
HE
Institute of Cancer Research, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Mitchell
A P
AP
D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D008540:Meiosis; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D013172:Spores, Fungal / Q000235:genetics; D014158:Transcription, Genetic