Transcription regulation of the Saccharomyces cerevisiae PHO5 gene by the Ino2p and Ino4p basic helix–loop–helix proteins
Article first published online: 19 DEC 2011
© 2011 Blackwell Publishing Ltd
Volume 83, Issue 2, pages 395–407, January 2012
How to Cite
He, Y., Swaminathan, A. and Lopes, J. M. (2012), Transcription regulation of the Saccharomyces cerevisiae PHO5 gene by the Ino2p and Ino4p basic helix–loop–helix proteins. Molecular Microbiology, 83: 395–407. doi: 10.1111/j.1365-2958.2011.07941.x
- Issue published online: 11 JAN 2012
- Article first published online: 19 DEC 2011
- Accepted 29 November, 2011.
The Saccharomyces cerevisiae PHO5 gene product accounts for a majority of the acid phosphatase activity. Its expression is induced by the basic helix–loop–helix (bHLH) protein, Pho4p, in response to phosphate depletion. Pho4p binds predominantly to two UAS elements (UASp1 at −356 and UASp2 at −247) in the PHO5 promoter. Previous studies from our lab have shown cross-regulation of different biological processes by bHLH proteins. This study tested the ability of all yeast bHLH proteins to regulate PHO5 expression and identified inositol-mediated regulation via the Ino2p/Ino4p bHLH proteins. Ino2p/Ino4p are known regulators of phospholipid biosynthetic genes. Genetic epistasis experiments showed that regulation by inositol required a third UAS site (UASp3 at −194). ChIP assays showed that Ino2p:Ino4p bind the PHO5 promoter and that this binding is dependent on Pho4p binding. These results demonstrate that phospholipid biosynthesis is co-ordinated with phosphate utilization via the bHLH proteins.