Yap5 is an iron-responsive transcriptional activator that regulates vacuolar iron storage in yeast.
The transporter Ccc1 imports iron into the vacuole, which is the major site of iron storage in fungi and plants. CCC1 mRNA is destabilized under low-iron conditions by the binding of Cth1 and Cth2 to the 3' untranslated region (S. Puig, E. Askeland, and D. J. Thiele, Cell 120:99-110, 2005). Here, we show that the transcription of CCC1 is stimulated by iron through a Yap consensus site in the CCC1 promoter. We identified YAP5 as being the iron-sensitive transcription factor and show that a yap5Delta strain is sensitive to high iron. Green fluorescent protein-tagged Yap5 is localized to the nucleus and occupies the CCC1 promoter independent of the iron concentration. Yap5 contains two cysteine-rich domains, and the mutation of the cysteines to alanines in each of the domains affects the transcription of CCC1 but not DNA binding. The fusion of the Yap5 cysteine-containing domains to a GAL4 DNA binding domain results in iron-sensitive GAL1-lacZ expression. Iron affects the sulfhydryl status of Yap5, which is indicative of the generation of intramolecular disulfide bonds. These results show that Yap5 is an iron-sensing transcription factor and that iron regulates transcriptional activation.
Li
Liangtao
L
Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
Bagley
Dustin
D
Ward
Diane M
DM
Kaplan
Jerry
J
D050976:Basic-Leucine Zipper Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D027682:Cation Transport Proteins; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003545:Cysteine; D000939:Epitopes; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D017930:Genes, Reporter; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D007763:Lac Operon; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism*
D050976:Basic-Leucine Zipper Transcription Factors; C089360:CCC1 protein, S cerevisiae; D027682:Cation Transport Proteins; D000939:Epitopes; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; C526591:Yap5 protein, S cerevisiae; D007501:Iron; D003545:Cysteine