Biology subjects

Schoenherr, R.

Publications and source records attributed to Schoenherr, R..

4 recordsLinked to original sources

bioRxiv2026

Structural compatibility enables functional co-assembly of Kir2.1 channels and the voltage-sensing domain of voltage-sensitive phosphatases

Voltage-sensing domains (VSDs), which are integral parts of voltage-gated K+ channel (KV) proteins, are highly modular protein components that function largely independently of ion-conducting pores - a property exploited in genetically encoded voltage indicators (GEVIs). Conversely, inward-rectifier K+ channels such as Kir2.1 possess a pore-only architecture and lack a VSD. Here, we demonstrate an unexpected and functionally relevant structural compatibility between the independently evolved pore-only and VSD-only membrane protein families. When co-expressed, Kir2.1 and ASAP-type GEVIs form complexes that constrain VSD movement and markedly interfere with voltage-dependent fluorescence responses. Molecular modeling combined with targeted mutagenesis identified a conserved hydrophobic interface that mediates this interaction. A single bulky substitution in the VSD of the GEVI rEstus-NI (A79W) disrupted the impact of Kir2.1 while preserving the GEVIs voltage-sensing performance. These findings suggest that pore-only and VSD-only proteins can assemble into functional KV-like architectures, and highlight that membrane proteins may engage in unexpected interactions capable of altering experimental readouts in physiological voltage imaging studies. The study also raises the possibility that independently functional membrane proteins may assemble into previously unrecognized higher-order complexes with distinct functional properties under native physiological conditions.

physiology↗

bioRxiv2026

Sub-Millivolt Voltage Imaging Reveals Gap Junction-Mediated Bioelectric Contact Inhibition

Sub-millivolt membrane potential (Vm) dynamics in multicellular non-excitable networks have remained largely invisible due to a lack of sufficiently sensitive imaging tools. Here, we introduce rEstus2s, a next-generation genetically encoded voltage indicator that overcomes this barrier by enabling high-resolution Vm imaging across the full physiological resting Vm range (-100 to 0 mV). Using rEstus2s, we uncover bioelectric contact inhibition (BCI), a fundamental biophysical principle where gap junction coupling acts as a passive noise filter to stabilize Vm. We demonstrate that the time-dependent variance of Vm (electrical volatility) relative to the number of cells (n) in a network follows a 1/n scaling law, reflecting a transition from stochastic single-cell behavior to collective electrical stability. While Ca2+-activated oncogenic ion channels, including ANO1 and KCa3.1, promote pronounced electrical volatility in isolated cells, BCI effectively attenuates volatility in electrically coupled networks. Disruption of gap junction coupling in cancer cells abolishes BCI and restores high electrical volatility. These findings establish a unifying biophysical framework for understanding how multicellularity maintains electrical homeostasis in health and disease. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=168 SRC="FIGDIR/small/701308v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@120fcb9org.highwire.dtl.DTLVardef@affa2aorg.highwire.dtl.DTLVardef@150ffa7org.highwire.dtl.DTLVardef@c05392_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2023

An ultrasensitive genetically encoded voltage indicator uncovers the electrical activity of non-excitable cells

Genetically encoded voltage indicators (GEVIs) are powerful, non-invasive tools for recording action potentials in excitable cells. However, most animal cell types are non-excitable, and yet variations in the membrane potential are biologically relevant in these cells as well. Resolving such small voltage signals demands GEVIs with exceptionally high sensitivity. In this study, we applied structure-guided engineering to the GEVI ASAP3 to generate rEstus, a sensor with optimized brightness, voltage sensitivity, and voltage range. rEstus is most sensitive in the resting voltage range of non-excitable cells, exhibits a 3.6-fold improvement in fast voltage spike detection, and allows for absolute voltage calibration at the single-cell level. Using rEstus, we resolved endogenous voltage fluctuations in several non-excitable cell types and demonstrate that correlation analysis of these optically recorded fluctuations provides an easy, non-invasive, real-time readout of electrical gap-junction coupling. Our work provides greatly enhanced tools and methods for the non-invasive study of electrical signaling in excitable and non-excitable cells.

biophysics↗

bioRxiv2023

InCellCryst - A streamlined approach to structure elucidation using in cellulo crystallized recombinant proteins

With the advent of serial X-ray crystallography on microfocus beamlines at free-electron laser and synchrotron facilities, the demand for protein microcrystals has significantly risen in recent years. However, by conventional methods extensive efforts are usually required to purify proteins and produce sufficiently homogeneous microcrystals. Here, we present InCellCryst, an advanced pipeline for producing homogeneous microcrystals directly within living insect cells. Our baculovirus-based cloning system enables the production of crystals from completely unmodified proteins as well as the screening of different cellular compartments to maximize chances for protein crystallization. By optimizing cloning procedures, recombinant virus production, crystallization and crystal detection, X-ray diffraction data can be collected 24 days after the start of target gene cloning. Furthermore, new strategies for serial synchrotron diffraction data collection directly from crystals within living cells abolish the need to purify the recombinant protein or the associated microcrystals.

biophysics↗