Indole and other aromatic compounds activate the yeast TRPY1 channel

The yeast TRPY1 (Yvc1p) channel is activated by membrane stretch to release vacuolar Ca2+ into the cytoplasm upon osmotic upshock. Exogenously added indole greatly enhances the upshock-induced Ca2+ release in vivo. Indole also reversibly activates the channels under patch clamp. A minimum of 10−6 M Ca2+ is needed for membrane stretch force to open TPRY1, but indole activation appears to be Ca2+ independent. A deletion of 30 residues at the predicted cytoplasmic domain, 570–600Δ, renders TRPY1 insensitive to stretch force upto 10−3 M Ca2+. Nonetheless, indole readily activates this mutant channel. Several other aromatic compounds, e.g. the antimicrobial parabens, also activate TRPY1. These compounds likely alter the innate forces in the lipid bilayer received by the channel.