High impact information on IME1

• (1988) found that overexpression of IME1 allowed sporulation in the presence of glucose and nitrogen [1].
• Thus, while it is clear that IME1 is a necessary positive regulator of meiosis, responding both to mating type and nutritional conditions, it is not clear if it is sufficient [1].
• We conclude that IME1 is a positive regulator of meiosis that normally is repressed by RME1 [2].
• Starvation for nitrogen further induced (6- to 8-fold) transcription of IME1, but, as expected, the induction was found only in MATa/MAT alpha or rme1-1/rme1-1 diploids [2].
• IME1 (Inducer of MEiosis) was cloned due to its high copy number effect: it enabled MAT insufficient strains to undergo meiosis [2].

Biological context of IME1

• The gene IME1 is also involved in starvation control of meiosis [3].
• Moreover, the addition of cAMP to a cyr1-2 diploid suppresses IME1 transcription [3].
• Multicopy IME1 plasmids overcome the meiotic deficiency of bcy1 and of RASval19 diploids [3].
• This indicates that the pathway downstream of the AC/PK cascade branches to control meiosis through IME1, and to control entry into G0 and cell cycle initiation, independently of IME1 [3].
• Thus, in wild-type strains, the increased expression of IME1 in starved a/alpha cells can account entirely for cell type control, but only partially for nutritional control, of early sporulation-specific gene expression [4].

Associations of IME1 with chemical compounds

• The deduced IME1 product is a 360-amino-acid protein with a tyrosine-rich C-terminal region [4].
• BACKGROUND: IME1, which is required for the initiation of meiosis, is regulated by Cln3:Cdc28 kinase, which activates the G1-to-S transition, and Snf1 kinase, which mediates glucose repression [5].
• We further show that this nutrient signal is transmitted to Rim11 and consequently to Ime1 by the cyclic AMP/protein kinase A signal transduction pathway [6].
• On the contrary, the activation of TOR by glutamine induces the relocalization of Ime1 to the cytoplasm [7].
• Ime1 is a transcriptional activator that is required for transcription of IME2, a serine/threonine protein kinase [8].

Physical interactions of IME1

• We show that Rme1p binds to two sites in the IME1 upstream region, near nt -1950 and -2030 [9].
• YHP1 encodes a new homeoprotein that binds to the IME1 promoter in Saccharomyces cerevisiae [10].
• Here, we characterize mutant Ime1p derivatives that interact with Rim11p but are not phosphorylated in vitro [11].
• By engineering constructs which express various portions of the Ime1p fused to either the DNA binding or transcriptional activation domains of GAL4, we have conclusively demonstrated that IME1 is a transcription factor, apparently required for sporulation to activate the transcription of meiosis specific genes [12].

Enzymatic interactions of IME1

• In addition, HA-RIM11 immune complexes phosphorylate a functional IME1 derivative but not the corresponding ime1-L321F derivative [13].
• These results argue that Ime1p must be phosphorylated to interact with Ume6p [11].

Regulatory relationships of IME1

• The adenylate cyclase/protein kinase cascade regulates entry into meiosis in Saccharomyces cerevisiae through the gene IME1 [3].
• We propose that RIM11 stimulates meiotic gene expression through phosphorylation of IME1 [13].
• Furthermore, mds3 pmd1 mutants express significant levels of IME1 even in vegetative cells and this unscheduled expression results in premature sporulation [14].
• In addition, Rme1 is assumed to repress IME1 expression [15].
• Accordingly, we propose that the IME1 product stimulates meiosis mainly through activation of IME2 expression [16].

Other interactions of IME1

• This observation indicates that MCK1 is required, independently, for both the activation of IME1 and subsequent ascus maturation [17].
• We report here an analysis of the regulatory region of IME2, an IME1-dependent meiotic gene [18].
• We propose that IME1 modifies UME6 to convert it from a negulator to a positive Regulor [18].
• Analysis of RIM11, a yeast protein kinase that phosphorylates the meiotic activator IME1 [13].
• Two-hybrid interaction assays suggest that Ime1p-Ume6p interaction is diminished in a rim15 mutant [19].

Analytical, diagnostic and therapeutic context of IME1

• Northern blot analysis revealed that suppression is due to increased IME1 transcript accumulation [14].
• Sequence analysis of IME1 revealed the presence of two almost identical 30- to 32-bp repeats [20].
• Dissection of the DNA binding domain of yeast Zn-finger protein Rme1p, a repressor of meiotic activator IME1 [21].

References