Variations in mRNA transcript levels of cell wall-associated genes of Saccharomyces cerevisiae following spheroplasting

Abstract

mRNA transcript levels of 38 genes from Saccharomyces cerevisiae were investigated during attempted spheroplast regeneration. Many of the genes selected are involved in cell wall biosynthesis. Spheroplasts did not regenerate into osmotically competent cells during the experiment. However, at a mRNA level, the quantities of transcripts were altered between the experimental and control populations. KRE11, EGT2 and MSS10 had their transcript levels increased by more than 10-fold during attempted spheroplast regeneration. A further six genes, FLO1, TIR1, SED1, HKR1, YGR189 and MUC1, showed transcript level increases of at least 5-fold. Five genes showed a change in transcript levels from an undetectable level to a detectable level: SKT5, KRE1, KRE5, SEC53 and DHS1. PMT2 showed a rapid decrease in mRNA levels followed by an increase to the basal level. Thus, cell stress genes, biosynthetic genes and some glycosylphosphatidylinositol-anchored cell wall proteins have their transcript levels increased in regenerating spheroplasts, but their transcription was not sufficient to initiate the replacement of the cell wall in liquid medium. ß

The sensing of nutritional status and the relationship to filamentous growth inSaccharomyces cerevisiae

“…Although the speci¢c genes and mechanism through which this occurs have not been identi¢ed, it is very likely to involve at least Msn1p, Muc1p and Flo1p. MSN1 encodes a transcription factor of MUC1 [45,46] and was shown to be induced 10-fold in cells of which the integrity of the cell wall was compromised [184]. In the same cells, transcription of FLO1 and MUC1 was found to increase ¢ve-fold [184].…”

“…Indeed, some evidence exists that suggests that nutrient starvation and environmental stresses might be physiologically connected and that they elicit similar and overlapping responses [180^182]. MSN1 encodes a transcription factor of MUC1 [45,46] and was shown to be induced 10-fold in cells of which the integrity of the cell wall was compromised [184]. In addition to this nutrient starvation-induced stress response, other environmental stresses were also shown to result in pseudohyphal and invasive growth.…”

“…Filamentous growth might be such a commonly elicited response by yeast cells to direct growth towards better, stress-free substrates. In the same cells, transcription of FLO1 and MUC1 was found to increase ¢ve-fold [184]. Mild heat (37 ‡C) and osmotic shock (1 M NaCl) were shown to induce ¢lamentous growth [183].…”