Tryptophan recovers sensitivity to cell membrane stress in Saccharomyces cerevisiae

Abstract

Sodium dodecyl sulfate is a detergent that disrupts cell membranes, activates cell wall integrity signaling and restricts cell growth in Saccharomyces cerevisiae. However, the underlying mechanism of how sodium dodecyl sulfate inhibits cell growth is not fully understood. Because deletion of the MCK1 gene leads to sensitivity to sodium dodecyl sulfate, we implemented a suppressor gene screening revealing that the TAT2 tryptophan permease rescues cell growth to sodium dodecyl sulfate-treated{Delta} mck1 cells. Therefore, we questioned the involvement of tryptophan in the response to sodium dodecyl sulfate treatment. In this work, we show that{Delta} trp1 cells have a disadvantage in the response to sodium dodecyl sulfate compared to auxotrophy for adenine, histidine, leucine or uracil. While also critical in the response to tea tree oil, TRP1 does not avert growth inhibition due to other cell wall/membrane perturbations that activate cell wall integrity signaling such as calcofluor white, Congo Red or heat stress. This implicates a distinction from the cell wall integrity pathway and suggests specificity to membrane stress as opposed to cell wall stress. We discover that tyrosine biosynthesis is also essential upon sodium dodecyl sulfate perturbation whereas phenylalanine biosynthesis appears dispensable. Finally, we observe enhanced tryptophan import within minutes upon exposure to sodium dodecyl sulfate indicating that these cells are not starved for tryptophan. In summary, our results expose a functional link between internal tryptophan levels and tryptophan biosynthesis in the response to plasma membrane damage.