Genetic evidence for transcriptional activation by the yeast IME1 gene product.
IME1 is required in yeast for meiosis and for expression of IME2 and other early meiotic genes. IME1 is a 360-amino acid polypeptide with central and C-terminal tyrosine-rich regions. We report here that a fusion protein composed of the lexA DNA-binding domain and IME1 activates transcription in vivo of a reporter gene containing upstream lexA binding sites. Activation by the fusion protein shares several features with natural IME1 activity: both are dependent on the RIM11 gene product; both are impaired by the same ime1 missense mutations; both are restored by intragenic suppressors. The central tyrosine-rich region is sufficient to activate transcription when fused to lexA. Deletion of this putative activation domain results in a defective IME1 derivative. Function of the deletion derivative is restored by fusion to the acidic Herpesvirus VP16 activation domain. The C-terminal tyrosine-rich region is dispensable for transcriptional activation; rather it renders activation dependent upon starvation and RIM11. Immunofluorescence studies indicate that an IME1-lacZ fusion protein is concentrated in the nucleus. These observations are consistent with a model in which IME1 normally stimulates IME2 expression by providing a transcriptional activation domain at the IME2 5' regulatory region.
Smith
H E
HE
Institute of Cancer Research, Columbia University, New York, New York 10032.
Driscoll
S E
SE
Sia
R A
RA
Yuan
H E
HE
Mitchell
A P
AP
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D013329:Structure-Activity Relationship; D014157:Transcription Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099160:LexA Repressor Protein; C080326:IME1 protein, S cerevisiae