Mechanotransduction (MET) channels reside at the tips of inner ear hair?cell stereocilia, where they mediate the conversion of sound?induced mechanical stimuli into electrical signals that are transmitted to the brain. Theseminiaturemachinesopeninresponsetomechanicalchangeandallowaselectiveinfluxofcationsinto hair cells. Their molecular identity has already been pursued for over two decades. Excitingly, a number of membraneproteinshavebeenrecentlyimplicatedascriticalcomponentsoftheMETchannelcomplex:TMC1, TMHSandTMIE.Thedysfunctionofanyoftheseproteinsisassociatedwithhearingloss.Todate,strategies forpharmacologicalinterventionaregreatlylimited,partlyduetolackofourunderstandingoftheseproteins' respective role during mechanotranduction. The goal of this project is to illuminate these proteins' atomic structure,theirinterplay,andtheirmechanismoftheaction.Here,wewillintegrateexperimentaltechniques includingsingleparticlecryo?electronmicroscopy,proteinbiochemistryandengineering,inordertoprovidea detailed understanding of these proteins' mechanical and structural properties. Atomic structures will help identify the long?sought pore?forming domain of the MET channel, through which ion flux occurs. The structures will also help identify gating and regulatory domains, which may be key to modulating the ion channel function. By establishing a structural basis for the MET channel function and regulation, we expect thattheproposedresearchwillhelpindesignofnovelpharmaceuticalapproachesfortargetinghearingloss.
Vertebrate hearing relies on the proper function of mechanotransduction (MET) ion channel proteins, which transduce mechanical stimuli into electrical signals that are transmitted to the brain. Recently, a number of membrane proteins have been implicated as critical components of the inner ear MET channel complex. The aim of this proposal is to uncover the atomic structures of these component proteins, specifically TMC1, TMHS and TMIE. This will set the stage for further mutagenesis studies on their mechanical properties, motions and interactions using biophysical and structural approaches.