Phospholipase C Regulates Transcription by Modifying Histone Acetylation Levels

In Saccharomyces cerevisiae , phospholipase C (Plc1p encoded by PLC1 gene) is the only source of inositol polyphosphates (InsPs). Deletion of PLC1 ( plc1Δ ) results in slow growth, defective expression of number of inducible genes, benomyl sensitivity and several other phenotypes. The benomyl sensitivity of plc1Δ cells is caused by a defect in the expression of FLR1 gene that encodes a plasma membrane transporter. The aim of this study was to use FLR1 as a model inducible gene and elucidate why it is not expressed in plc1Δ cells. Our results showed that plc1Δ cells display a decreased level of recruitment of SWI/SNF chromatin remodeling complex and SAGA histone acetyltransferase complex and decreased acetylation of histone H3 in FLR1 promoter. Our kinetic studies indicate that histone acetylation and occupancy of SWI/SNF at the FLR1 promoter are required for its sustained expression. The mechanism of SWI/SNF occupancy might involve interaction of acetylated histones with a bromodomain in the SWI/SNF complex. The results are consistent with a model in which Plc1p and InspPs‐supported acetylation of histones are important for bromodomain‐mediated SWI/SNF retention and FLR1 expression.