Piezo1 is a mechanosensitive channel that converts applied force into electrical signals. Partial molecular structures show a bowl-shaped trimer with extended arms. Here we use cryo-electron microscopy (cryo-EM) to show that Piezo1 adopts different degrees of curvature in lipid vesicles of different size. We also use high-speed atomic force microscopy (HS-AFM) imaging to analyze the deformability of Piezo1 under force in membranes on a mica surface: Piezo1 can be flattened reversibly into the membrane plane. By approximating the absolute force applied, we estimate a range of values for a mechanical spring constant for Piezo1. Both methods demonstrate that Piezo1 can deform its shape towards a planar structure. This deformation could explain how lateral membrane tension can be converted into a conformation-dependent free energy change to gate the Piezo1 channel in response to mechanical perturbations.

Living cells are viscoelastic materials, with the elastic response dominating at long timescales (≳1 ms)1. At shorter timescales, the dynamics of individual cytoskeleton filaments are expected to emerge, but active microrheology measurements on cells accessing this regime are scarce2. Here, we develop high-frequency microrheology (HF-MR) to probe the viscoelastic response of living cells from 1Hz to 100 kHz. We report the viscoelasticity of different cell types and upon cytoskeletal drug treatments. At previously inaccessible short timescales, cells exhibit rich viscoelastic responses that depend on the state of the cytoskeleton. Benign and malignant cancer cells revealed remarkably different scaling laws at high frequency, providing a univocal mechanical fingerprint. Microrheology over a wide dynamic range up to the frequency of action of the molecular components provides a mechanistic understanding of cell mechanics.

Conventional atomic force microscopes (AFMs) take at least 30-60 s to capture an image, while dynamic biomolecular processes occur on a millisecond timescale or less. To narrow this large difference in timescale, various studies have been carried out in the past decade. These efforts have led to a maximum imaging rate of 30-60 ms/ frame for a scan range of~250 nm, with a weak tip-sample interaction force being maintained. Recent imaging studies using high-speed AFM with this capacity have shown that this new microscope can provide straightforward and prompt answers to how and what structural changes progress while individual biomolecules are at work. This article first compares high-speed AFM with its competitor (single-molecule fluorescence microscopy) on various aspects and then describes high-speed AFM instrumentation and imaging studies on biomolecular processes. The article concludes by discussing the future prospects of this cutting-edge microscopy.