HSF and Msn2/4p can exclusively or cooperatively activate the yeast HSP104 gene.
In an effort to understand how an accurate level of stress-specific expression is obtained, we studied the promoter of the yeast HSP104 gene. Through 5' deletions, we defined a 334 bp fragment upstream of the first coding AUG as sufficient and essential for maximal basal activity and a 260 bp fragment as sufficient and essential for heat shock responsiveness. These sequences contain heat shock elements (HSEs) and stress response elements (STREs) that cooperate to achieve maximal inducible expression. However, in the absence of one set of factors (e.g. in msn2Deltamsn4Delta cells) proper induction is obtained exclusively through HSEs. We also show that HSP104 is constitutively derepressed in ras2Delta cells. This derepression is achieved exclusively through activation of STREs, with no role for HSEs. Strikingly, in ras2Deltamsn2Deltamsn4Delta cells the HSP104 promoter is also derepressed, but in this strain derepression is mediated through HSEs, showing the flexibility and adaptation of the promoter. Thus, appropriate transcription of HSP104 is usually obtained through cooperation between the Msn2/4/STRE and the HSF/ HSE systems, but each factor could activate the promoter alone, backing up the other. Transcription control of HSP104 is adaptive and robust, ensuring proper expression under extreme conditions and in various mutants.
Grably
Melanie R
MR
Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Stanhill
Ariel
A
Tell
Osnat
O
Engelberg
David
D
D000251:Adenosine Triphosphatases / Q000235:genetics; D018829:Adhesins, Bacterial / Q000378:metabolism*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D017930:Genes, Reporter; D006360:Heat-Shock Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
D018829:Adhesins, Bacterial; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006360:Heat-Shock Proteins; C102673:Hsf protein, bacteria; C081935:MSN2 protein, S cerevisiae; C081937:MSN4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C070972:HsP104 protein, S cerevisiae; D001616:beta-Galactosidase; D000251:Adenosine Triphosphatases