The Effect of Indole and Related Compounds on Aequorin Luminescence and Hyperosmotic Shock Response in Saccharomyces cerevisiae

Abstract

In eukaryotic cells, Transient Receptor Potential (TRP) channels act in response to various stimuli to produce responses. Multiple stimuli may affect TRP channels, although the mechanism for this convergence has been incompletely characterized to date. There is a single TRP channel gene in the Saccharomyces cerevisiae genome coding for a 676 amino acid vacuolar protein, Yvc1p. Ca2+ ions travel from the vacuole through Yvc1p to reach the cytoplasm; this process is activated directly by both hyperosmotic shock (Zhou XL et al (2003) Proc Natl Acad Sci USA 100: 7105-7110) and cytoplasmic Ca2+ (Bertl A, Slayman CL (1990) Proc Natl Acad Sci USA 87: 7824-7828). John Haynes, et al (Haynes et al FEBS Letters 582 (2008) 1514 – 1518) demonstrated direct activation of Yvc1p by Indole and related compounds (Tryptamine, Indoleacetic acid, Tyramine, Quinoline, and Parabens). They additionally showed that the hyperosmotic shock effect could be enhanced by the same compounds.In this study, we use an in vivo luminescence assay to detail the effects of Indole-related compounds on cytoplasmic aequorin expressed in Saccharomyces cerevisiae. We observe a variable response to the aromatic compounds Indole and Tryptamine. In some cases, the compounds appear to act selectively on Yvc1p: they enhance luminescence above that observed in wild-type strains, but have no effect on ΔYVC1 control strains. At other times, ΔYVC1 control strains show a response to the compounds, indicating the compounds either activate aequorin directly, or work through a non-Yvc1p dependent mechanism. We are currently working to understand the basis of this variability.