Structure of the ancestral TRPY1 channel fromSaccharomyces cerevisiaereveals mechanisms of modulation by lipids and calcium

Abstract

Transient Receptor Potential (TRP) channels have evolved in eukaryotes to control various cellular functions in response to a wide variety of chemical and physical stimuli. This large and diverse family of channels emerged in fungi as mechanosensitive osmoregulators. The Saccharomyces cerevisiae vacuolar TRP yeast 1 (TRPY1) is the most studied TRP channel from fungi, but the molecular details of channel modulation remain elusive so far. Here, we describe the full-length cryo-electron microscopy structure of TRPY1 at 3.1 A resolution. The structure reveals a distinctive architecture for TRPY1 among all eukaryotic TRP channels with an evolutionarily conserved and archetypical transmembrane domain, but distinct structural folds for the cytosolic N- and C-termini. We identified the inhibitory phosphatidylinositol 3‐phosphate (PI(3)P) lipid binding site, which sheds light into the lipid modulation of TRPY1 in the vacuolar membrane. The structure also exhibited two Ca2+-binding sites: one in the cytosolic side, implicated in channel activation, and the other in the vacuolar lumen side, involved in channel inhibition. These findings, together with data from molecular dynamics simulations, provide structural insights into the basis of TRPY1 channel modulation by lipids and calcium.

Activity of the yeast vacuolar TRP channel TRPY1 is inhibited by Ca2+–calmodulin binding

“…It is encoded by the gene YVC1 (yeast vacuolar conductance 1) and forms ion channels in the yeast vacuolar membrane (2)(3)(4)(5). Recently, the Moissenkova-Bell group described the full-length structure of TRPY1 by cryo-electron microscopy with typical tetrameric TRP channel architecture, in which subunits are arranged in a four-fold symmetry around a central ion permeation path, as previously suggested (1,6,7), but with distinct structural folds for the cytosolic N-and C-termini (8).…”