Induction of DAN/TIR yeast cell wall mannoprotein genes in response to high hydrostatic pressure and low temperature

Global transcriptional profiles of Saccharomyces cerevisiae were studied following changes in growth conditions to high hydrostatic pressure and low temperature. These profiles were quantitatively very similar, encompassing 561 co-upregulated genes and 161 co-downregulated genes. In particular, expression of the DAN/TIR cell wall mannoprotein genes, which are generally expressed under hypoxia, were markedly upregulated by high pressure and low temperature, suggesting the overlapping regulatory networks of transcription. In support of the role of the mannoproteins in cell wall integrity, cells acquired resistance against treatment with SDS, Zymolyase and lethal level of high pressure when preincubated under high pressure and low temperature. Keywords: stress response Cells of strain BY4742 were grown until cell density of 1-2 × 10^7 cells/ml at 0.1 MPa and 24 °C had been reached with a volume of 50 ml in a 100-ml conical flask. Total RNA was prepared from the cells for the control sample using the hot phenol method. Cells were also incubated at 25 MPa and 24 °C or 0.1 MPa and 15 °C for 5 h, followed by total RNA preparation. To average accidental errors in total RNA preparation, equal amounts of total RNA purified from three independent cultures under each condition were mixed and the mixture was used for the experiments. Subsequent procedures including the isolation of poly A+-RNA, sample labeling and hybridization for DNA microarrays were performed by NimbleGen Systems Inc. (Madison, WI, USA) and GeneFrontier Inc. (Tokyo, Japan). Fifteen perfectly matching 60-mer probes for individual genes were used for hybridization. Because this analysis yields results with a high confidence level, a 1.5-fold difference between multiple samples generally corresponds to the level of significance (P < 0.05) obtained from hybridization signals from 15 perfectly matching probes for each gene.