Dielectric Spectroscopy Based Detection of Specific and Nonspecific Cellular Mechanisms

Using radiofrequency dielectric spectroscopy, we have investigated the impact of the interaction between a G protein-coupled receptor (GPCR), the sterile2 alpha-factor receptor protein (Ste2), and its cognate agonist ligand, the alpha-factor pheromone, on the dielectric properties of the plasma membrane in living yeast cells (Saccharomyces cerevisiae). The dielectric properties of a cell suspension containing a saturating concentration of alpha-factor were measured over the frequency range 40Hz-110 MHz and compared to the behavior of a similarly prepared suspension of cells in the absence of alpha-factor. A spherical three-shell model was used to determine the electrical phase parameters for the yeast cells in both types of suspensions. The relative permittivity of the plasma membrane showed a significant increase after exposure to alpha-factor (by 0.06 +/- 0.05). The equivalent experiment performed on yeast cells lacking the ability to express Ste2 showed no change in plasma membrane permittivity. Interestingly, a large change also occurred to the electrical properties of the cellular interior after the addition of alpha-factor to the cell suspending medium, whether or not the cells were expressing Ste2. We present a number of different complementary experiments performed on the yeast to support these dielectric data and interpret the results in terms of specific cellular reactions to the presence of alpha-factor.

Automated summary

This study investigated the impact of the interaction between a GPCR and its agonist ligand on the dielectric properties of the plasma membrane in living yeast cells using radiofrequency dielectric spectroscopy. The results showed a significant increase in plasma membrane permittivity after exposure to the agonist ligand, while cells lacking the ability to express the specific receptor showed no change. Interestingly, the electrical properties of the cellular interior also underwent a large change after the addition of the agonist, regardless of Ste2 expression.