Transcription of the phosphoglycerate kinase gene of Saccharomyces cerevisiae increases when fermentative cultures are stressed by heat‐shock

Abstract

The single gene for phosphoglycerate kinase (PGK) in the haploid genome of Saccharomyces cerevisiae is expressed to a very high level in cultures fermenting glucose. Despite this it responds to heat-shock, When S . cerevisiae growing exponentially on glucose media was shifted from 25 "C to 38 "C transient increases of 6 -7-fold in cellular PGK mRNA were observed. This elevation in PGK mRNA still occurred in the presence of the protein-synthesis inhibitor cycloheximide, but was not observed in cells bearing the rnal .I mutation. From the kinetics of continuous labelling of PGK mRNA, relative to the labelling of other RNAs in the same cultures whose levels do not alter with heat-shock, it was shown that the elevation in PGK mRNA in response to temperature upshift reflects primarily an increased synthesis of this mRNA and not an alteration of its half-life. PGK mRNA synthesis is therefore one target of a response mechanism to thermal stress.Synthesis of PGK enzyme in glucose-grown cultures is efficient after mild (25 "C to 38 "C) or severe (25 "C to 42 "C) heat-shocks. Following the severe shock, the synthesis of most proteins is abruptly terminated, but synthesis of PGK and a few other glycolytic enzymes continues at levels comparable to the levels of synthesis of most of those proteins dramatically induced by heat (heat-shock proteins). Cells that overproduce PGK due to the presence of multiple copies of the PGK gene on a high-copy-number plasmid continue their overproduction of this enzyme during severe thermal stress. Therefore PGK mRNA is both elevated in level in response to heatshock and translated efficiently at supra-optimal temperatures.Upon exposure to a heat shock the cells of virtually all species display alterations in their physiology and protein synthesis that together constitute the 'heat-shock response' (reviewed in [l -31). While this response involves primarily an altered control over gene transcription, it also operates in eukaryotes partly through effects on the translocation of mRNAs from the nucleus or the stabilisation and selective translation of mRNAs in the cytoplasm [2, 31. The transcriptional changes involve stimulation of a small number of heat-shock protein (HSP) genes and the simultaneous repression of many, if not most, of the genes that were previously active. Of the 17 proteins whose synthesis is enhanced when Escherichia coli cells are heat-shocked, a few have been assigned either an enzymatic function (e.g. the 1ysU and lon gene products) or a role in the control of enzyme activities (e. g. rpoD which encodes the regulatory sigma subunit of E. coli RNA polymerase) [I]. All 17 genes are activated during heat-shock by the product of the htpR locus, a protein which displays both a striking structural similarity to sigma and the apparent ability to antagonize the activity of sigma [l].Correspondence to P. W. Piper, Department of Biochemistry, University College London, Gower Street, London, England WC1 E 6BTAbbreviations and nomenclature. The nomenclature used for yeast heat-shock ...

Plasma-membrane ATPase action affects several stress tolerances of Saccharomyces cerevisiae and Schizosaccharomyces pombe as well as the extent and duration of the heat shock response

“…3 b). The temperature of 42 "C is about 3 "C above the maximum for growth, and close to the maximum temperature at which S. cerevisiae will still display synthesis of HSPs (Piper et al, 1986. Normally, after cells are shifted to 42 "C, an initial 'burst' of HSP synthesis is followed by a progressive cessation of all protein synthesis over about 1 h. This is apparent from the labelling of S. cerevisiae ~1278b in Fig.…”

“…pombe cells actively growing at 25 "C are shifted to 48 "C there is rapid protein synthesis arrest; no HSPs are synthesized and these cells, uninduced for thermotolerance, quickly die. Pulselabelling studies have shown that neither yeast can synthesize HPSs above 42-43 "C (Piper et al, 1986; also unpublished observations). At 48 "C pmal .l conferred higher thermotolerance (Figs 1 a and 2a).…”

“…The high thermotolerance of Go cells may be due in part to the induction of HSP genes with the decline in cyclic AMP levels as cells enter stationary phase (Boucherie, 1985;Iida & Yahara, 1984;Shin et al, 1987). A few of the proteins made in heat-shocked S. cerevisiae correspond to glycolytic enzymes that are also made by unstressed cells (Piper et al, 1986. Furthermore, we recently identified the gene for plasma membrane ATPase (PMAI) as one of the few in S. cerevisiae still efficiently transcribed after heat shock to 42 "C, approximately 3 "C above the maximum growth temperature.…”

Rice ASR1 Protein with Reactive Oxygen Species Scavenging and Chaperone-like Activities Enhances Acquired Tolerance to Abiotic Stresses in Saccharomyces cerevisiae

“…Fba1p, which encodes fructose-1,6-biphosphate aldolase was required for glycolysis and gluconeogenesis and located in mitochondrial outer membrane surface upon oxidative stress (Rinnerthaler et al, 2006). Pgk1p was abundantly expressed in cells grown in glucose, and transcription was increased by heat shock (Piper et al, 1986) and regulated by the transcription factors Rab1p, Abf1p, and Reb1p (Packham et al, 1996). In particular, enolase and Ssb protein are major targets of protein damage in WT yeast cells exposed to oxidative stress (Cabiscol et al, 2000;Reverter-Branchat et al, 2004).…”

Stimulation of Yeast 3-Phosphoglycerate Kinase Gene Promoter by Paraquat

“…4). Piper et al (18) concluded that the role of PGK may be to assist cells repressed in mitochondrial function during recovery following heat shock. In our experiments, the observation that PGK promoter stimulation was observed only at midlog phase in cells cultured in PQ-containing medium, and not after a 1 h exposure to the oxidant, further supports the notion that PGK is especially required in the recovery stage.…”