Plc1p is required for SAGA recruitment and derepression of Sko1p-regulated genes.
In Saccharomyces cerevisiae, many osmotically inducible genes are regulated by the Sko1p-Ssn6p-Tup1p complex. On osmotic shock, the MAP kinase Hog1p associates with this complex, phosphorylates Sko1p, and converts it into an activator that subsequently recruits Swi/Snf and SAGA complexes. We have found that phospholipase C (Plc1p encoded by PLC1) is required for derepression of Sko1p-Ssn6p-Tup1p-controlled osmoinducible genes upon osmotic shock. Although plc1Delta mutation affects the assembly of the preinitiation complex after osmotic shock, it does not affect the recruitment of Hog1p and Swi/Snf complex at these promoters. However, Plc1p facilitates osmotic shock-induced recruitment of the SAGA complex. Like plc1Delta cells, SAGA mutants are osmosensitive and display compromised expression of osmotically inducible genes. The reduced binding of SAGA to Sko1p-Ssn6p-Tup1p-repressed promoters in plc1Delta cells does not correlate with reduced histone acetylation. However, SAGA functions at these promoters to facilitate recruitment of the TATA-binding protein. The results thus provide evidence that Plc1p and inositol polyphosphates affect derepression of Sko1p-Ssn6p-Tup1p-controlled genes by a mechanism that involves recruitment of the SAGA complex and TATA-binding protein.
Guha
Nilanjan
N
Department of Biological Sciences, St. John's University, Queens, NY 11439, USA.
Desai
Parima
P
Vancura
Ales
A
D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism*; D001665:Binding Sites; D005800:Genes, Fungal; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009997:Osmotic Pressure; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D035181:TATA-Box Binding Protein / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism*
D050976:Basic-Leucine Zipper Transcription Factors; D019269:Phosphatidylinositol 4,5-Diphosphate; D012097:Repressor Proteins; C507785:SAGA complex, S cerevisiae; C077832:SKO1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035181:TATA-Box Binding Protein; D015534:Trans-Activators; D010738:Type C Phospholipases; C522285:Plc1 protein, S cerevisiae