DOI: 10.5061/dryad.stqjq2c8s
title: Data from: Nanomechanics of wild-type and mutant dimers of the tip-link protein protocadherin 15

description: Mechanical force controls the opening and closing of mechanosensitive ion
 channels atop the hair bundles of the inner ear. The filamentous tip link
 connecting transduction channels to the tallest neighboring stereocilium
 modulates the force transmitted to the channels and thus changes their
 probability of opening. Each tip link comprises four molecules: a dimer of
 protocadherin 15 and a dimer of cadherin 23, all of
 which are stabilized by Ca2+ binding. Using a high-speed optical trap to
 examine dimeric PCDH15, we find that the protein's configuration is
 sensitive to Ca2+ and that the molecule exhibits limited unfolding at a
 physiological Ca2+ concentration. PCDH15 can therefore modulate its
 stiffness without undergoing large unfolding events in physiological Ca2+
 conditions. The experimentally determined stiffness of PCDH15 accords with
 published values for the stiffness of the gating spring, the mechanical
 element that controls the opening of mechanotransduction channels. When
 PCDH15 has a point mutation, V507D, associated with non-syndromic hearing
 loss, unfolding events occur more frequently under tension and refolding
 events occur less often than in the wild-type protein. Our results suggest
 that the maintenance of appropriate tension in the gating spring is
 critical to the appropriate transmission of force to transduction
 channels, and hence to hearing.
description: These are force-extension datasets collected using a custom-built
 optical trap system. Custom written LabVIEW (2013) software was used to
 acquire the raw data. It has been calibrated and the zero position
 adjusted to correspond to three standard deviations below the mean
 position of the construct at the inter-ramp resting force of 1
 pN.
description: # Nanomechanics of wild-type and mutant dimers of the tip-link protein
 protocadherin 15 Camila M. Villasante<sup>1</sup>, Xinyue
 Deng<sup>1</sup>, Joel E. Cohen<sup>2,3,4</sup>,
 and A. J. Hudspeth<sup>1,5</sup>
 <sup>1</sup>Laboratory of Sensory Neuroscience, The
 Rockefeller University, New York, NY 10065 USA;
 <sup>2</sup>Laboratory of Populations, The Rockefeller
 University, New York, NY 10065 USA; <sup>3</sup>Earth
 Institute and Department of Statistics, Columbia University, New York, NY
 10027 USA; <sup>4</sup>Department of Statistics, University of
 Chicago, Chicago, IL 60637 USA; <sup>5</sup>Howard Hughes
 Medical Institute, The Rockefeller University, New York, NY 10065 USA
 Dryad DOI:
 [https://doi.org/10.5061/dryad.stqjq2c8s](https://doi.org/10.5061/dryad.stqjq2c8s) Associated with bioRxiv pre-print: [https://doi.org/10.1101/2023.10.17.562769](https://doi.org/10.1101/2023.10.17.562769) ## Description of the data and file structure All datasets underlying the work in *Nanomechanics of wild-type and mutant dimers of the tip-link protein protocadherin 15* are included in this repository. There are three constructs: wild-type PCDH15, V507D PCDH15, and the anchors only. There are three buffer conditions: saturating (3 mM) Ca<sup>2+</sup>, physiological (20 uM) Ca<sup>2+</sup>, and no Ca<sup>2+ </sup>(1 mM EDTA). Each dataset is an .hdf file containing a dictionary. The keys of the dictionary are: 'ywavecut', 'forcewavecut', 'ywavesmooth', and 'forcewavesmooth', and each corresponds to a Numpy array. 'ywavecut': end-to-end distance data (nm) that has been calibrated and the zero position adjusted to be three standard deviations below the mean position of the construct at the low inter-ramp resting force. The time range includes all cycles from a given dataset. The temporal resolution of the data is 10 μs. 'forcewavecut': force data (pN) that has been calibrated. The time range is the same as ywavecut. The temporal resolution of the data is 10 μs. 'ywavesmooth': end-to-end distance data (nm) that is the same as 'ywavecut' except it has been smoothed with a Savitzky-Golay filter with a window of 101 points, which reduced the temporal resolution of the data from 10 μs to 1 ms. 'forcewavesmooth': force data (pN) that is the same as 'forcewavecut' except it has been smoothed with a Savitzky-Golay filter with a window of 101 points, which reduced the temporal resolution of the data from 10 μs to 1 ms. ## Code/Software Scripts used to analyze this data are located in [https://github.com/cvillasante/VDCH-2023](https://github.com/cvillasante/VDCH-2023).