Tryptophan Permease Gene TAT2 Confers High-Pressure Growth in Saccharomyces cerevisiae

Abstract

Hydrostatic pressure in the range of 15 to 25 MPa was found to cause arrest of the cell cycle in G 1 phase in an exponentially growing culture of Saccharomyces cerevisiae, whereas a pressure of 50 MPa did not. We found that a plasmid carrying the TAT2 gene, which encodes a high-affinity tryptophan permease, enabled the cells to grow under conditions of pressure in the range of 15 to 25 MPa. Additionally, cells expressing the Tat2 protein at high levels became endowed with the ability to grow under low-temperature conditions at 10 or 15°C as well as at high pressure. Hydrostatic pressure significantly inhibited tryptophan uptake into the cells, and the Tat2 protein level was down-regulated by high pressure. The activation volume associated with tryptophan uptake was found to be a large positive value, 46.2 ؎ 3.85 ml/mol, indicating that there was a net volume increase in a rate-limiting step in tryptophan import. The results showing cell cycle arrest in G 1 phase and down-regulation of the Tat2 protein seem to be similar to those observed upon treatment of cells with the immunosuppressive drug rapamycin. Although rapamycin treatment elicited the rapid dephosphorylation of Npr1 and induction of Gap1 expression, hydrostatic pressure did not affect the phosphorylation state of Npr1 and it decreased the level of Gap1 protein, suggesting that the pressure-sensing pathway may be independent of Npr1 function. Here we describe high-pressure sensing in yeast in comparison with the TOR-signaling pathway and discuss an important factor involved in adaptation of organisms to high-pressure environments.

Exploration of the Effects of High Hydrostatic Pressure on Microbial Growth, Physiology and Survival: Perspectives from Piezophysiology

“…Regardless of other forms of auxotrophy, trp1 cells exhibit marked growth defects at 15-25 MPa due to reduced tryptophan uptake activity under high hydrostatic pressure, while tryptophan-prototrophic strains are capable of growth under the same condition. 51) In any case, the cells are completely viable. Consequently, trp1 cells accumulate in the G 1 phase of the cell cycle at 15-25 MPa.…”

“…It has been found that the ability of S. cerevisiae cells to grow at moderate pressure in the range of 15-25 MPa is directly connected with auxotrophy for tryptophan and the availability of this amino acid (see below). 51) Growth is arrested at pressures greater than 50 MPa regardless of the amino acid auxotrophy of the strain. Pressures in a range of 100 to 200 MPa kill cells of S. cerevisiae by disrupting the ultrastructure of microtubules, actin filaments or nuclear membranes.…”

“…Any factor that leads to increased tryptophan availability enables trp1 cells to grow at high pressure: The addition of excess tryptophan to the medium (e.g., 1 g/liter), introduction of the TRP1 gene or overexpression of tryptophan permease Tat1 or Tat2 confers the ability to grow at 25 MPa on trp1 cells. 51) Overexpression of Tat2 or Tat1 also confers the ability to grow at a low temperature 15 C. 51) The abilities to grow at high pressure and at low temperature converge on the physicochemical properties of lipid bilayers. The structure of lipid bilayers is particularly sensitive to changes in hydrostatic pressure and temperature.…”

Development of a low-pressure diamond anvil cell and analytical tools to monitor microbial activities in situ under controlled P and T

“…Saccharomyces cerevisiae is one of the best characterized unicellular eukaryote in terms of genome characterization and cellular physiology, and resistance to hydrostatic pressure [22][23][24][25]. The maximum pressure permissive to yeast cell growth is strain dependent, ranging from 15 to 50 MPa, while pressure above 200 MPa essentially kill the cells [26]. Ethanol fermentation from glucose is blocked at pressures higher than 50 MPa [27,28].…”

Global Screening of Genes Essential for Growth in High-Pressure and Cold Environments: Searching for Basic Adaptive Strategies Using a Yeast Deletion Library

“…We demonstrated that the uptake of tryptophan is a limiting factor for yeast cell growth at high pressure as well as at low temperature (Abe and Horikoshi 2000). Wild-type strains having trp1 as a nutrient auxotrophic marker (e.g., YPH499 or W303-1A) exhibit diminished cell growth at high pressure of 25 MPa at 24°o r at low temperature of 10°-15°at atmospheric pressure ($0.1 MPa ¼ 1 bar ¼ 0.9869 atm ¼ 1.0197 kg of force/cm 2 ; to avoid confusion, MPa is used throughout) although tryptophan-prototrophic strains can efficiently grow under the same conditions.…”