Mechanosensitive channels Piezo1 and Piezo2 play key roles in transduction of mechanical forces to cellular signals. They are of great importance to biological processes from appetite regulation and somatasensation, to cell growth and proliferation. In addition to mechanical stress, small molecules have been shown to interact with Piezo1. For instance, Yoda1 selectively activates Piezo1 at micromolar concentrations. To date, the structural mechanism of this process remained unknown. This is in no small part due to techinical challenges associated with experimental study. Both Piezo1 and Piezo2 exist as large triskelion homo-trimers, each subunit of which is thousands of amino acids in length. This sheer size, along with the membrane environment makes detailed structural studies difficult. Recently, cryo electron microscopy studies provided a high resolution structure for Piezo1. Using this structure as a starting point, we have conducted microsecond timescale all-atom simulations of Piezo1 to investigate structural mechanisms of activation via binding of Yoda1 and application of membrane tension. This has allowed us to locate a potential binding site and pathway for Yoda1 and to propose that Yoda1 acts as a molecular wedge to modulate propogation of conformational changes. Our binding site was validated with subsequent mutagenesis studies, showing that Yoda1 activation is silenced by mutation of key binding site alanine residues into bulky residues to induce steric barriers to Yoda1 binding. Furthermore, the proposed binding / insertion pathway is consistent with previous experimental studies, that suggest Yoda1 is more efficatious when applied intracellularly. Finally, we are currently investigating the free energy landscape of extracellular cap domain motions, which have been suggested to be correlated with transduction of shear flow and cytoskeletal attachment motions. It is hoped that this study may provide valuable insights for future structural and drug design investigations of Piezo 1 modulators.

Computational study of changes in conformational dynamics of Piezo1 induced by Yoda 1 agonist binding and membrane tension

2019 Fall National Meeting

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