About

Sergei Sukharev is a Professor in the Department of Biology at the University of Maryland, with affiliate positions in Chemistry and Biochemistry Graduate Program. He earned his Ph.D. from Moscow State University in 1987, focusing on molecular mechanisms of mechanosensation and mechano-activated ion channels, their structure, and mechanisms of gating by membrane stretch. His research investigates the principles and molecules that cells use to detect mechanical force and pressure, encompassing phenomena from bacterial adaptation to osmotic changes to complex processes such as hearing, balance, and gravitropism in animals and plants. Dr. Sukharev has made significant contributions to the field, notably in the isolation and cloning of the Mechanosensitive Channel of Large conductance of Escherichia coli (MscL), the first identified channel of this class. His work involves interdisciplinary approaches including molecular modeling, genetic modifications, biochemical purification, reconstitution into membranes, single-channel recording, and video imaging. His research addresses the structure and gating mechanisms of mechanosensitive channels, with a focus on understanding how interactions within these proteins keep channels closed at rest and allow them to open under tension. He has received awards such as the J. W. Ritter Award in 1988 and the University of Maryland College of Life Sciences Junior Faculty Award in 2000.

Research topics

• Chemistry
• Biophysics
• Biology
• Materials science
• Cell biology

Selected publications

• Desensitization, Inactivation, and the tension-proof safety mechanism of inactivated MscS

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-03-16

  articleOpen accessSenior author

  ABSTRACT MscS is the main low-threshold tension-activated osmolyte release valve in bacteria. Working alone or together with high-threshold MscL, it regulates turgor and protects cells from mechanical rupture during osmotic down-shock. The channel exhibits complex adaptive behavior, including desensitization and full inactivation, both of which occur at relatively low sub-lytic tension. There is debate over whether the commonly observed non-conductive state of MscS with the tension-sensing helices splayed away from the gate corresponds to the closed or inactivated state. In this work, using specialized pressure protocols in patch-clamp electrophysiology, we highlight the difference between reversible adaptation (desensitization) and inactivation. We show that inactivated channels cannot be reactivated with high tension, up to the limit of patch stability. This aligns with cryo-EM studies by Zhang et al. ( Nature , 2021, 590:509-5018), who applied extreme tension to the splayed nanodisc-reconstituted MscS (PDB 6VYK) by depleting lipids with cyclodextrin, and observed a new flattened but apparently non-conductive structure (PDB 6VYM). To characterize these two states, we performed a steered Molecular Dynamics simulation from the initial splayed structure to the flattened conformation, confirming that they are connected through a smooth conformational pathway and remain largely dehydrated and entirely non-conductive throughout the transition. The data show that the initial splayed conformation meets all the criteria of the inactivated state, distorting but not opening under extreme tension. By combining patch-clamp experiments with simulations based on cryo-EM data, we demonstrate that inactivated MscS resists activation, thereby maintaining the membrane barrier when tension exceeds the activation threshold. SIGNIFICANCE Bacterial energetics, which relies on the electrochemical proton gradient across the inner membrane as an intermediary, conflicts with the presence of a dense population of highly conductive mechano-activated channels in the same cytoplasmic membrane, which must be proton-tight. Moreover, the tension activation threshold for the common MscS channel is low and can be easily exceeded by fluctuations in the concentrations of internal or external osmolytes. In this paper, we describe the important adaptive inactivation of MscS at tensions near its activation threshold, and specifically, the complete resistance of inactivated MscS to opening at any tension. The data show another layer of tight regulation of MscS residing in the energy-coupling membranes.

  PublisherOA PDFDOI

• BPS2026 – Structural and functional characterization of Vibrio cholerae mechanosensitive channel MSCs

  Biophysical Journal · 2026-02-01

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  PublisherDOI

• BPS2026 – The altered stoichiometry of a non-inactivating mutant suggests the assembly sequence of the mechanosensitive channel MSCs

  Biophysical Journal · 2026-02-01

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• BPS2026 – Turgor-driven recovery of the bacterial mechanosensitive channel MscS leads to its compact closed state

  Biophysical Journal · 2026-02-01

  articleSenior author
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• BPS2025 - Improving the force field for lipid interactions with calcium and beryllium

  Biophysical Journal · 2025-02-01

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  PublisherDOI

• BPS2025 - The lipid-mediated mechanism of MscS inactivation

  Biophysical Journal · 2025-02-01

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• BPS2025 - Calculation of the free energy of binding of arginine-rich peptides to POPA/POPC lipid membrane using CUFIX parameters

  Biophysical Journal · 2025-02-01

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• Towards high-resolution <i>in-situ</i> structural biology of membrane protein complexes

  Structural Dynamics · 2025-09-01

  articleOpen access

  Membrane protein structure determination is technically challenging and further complicated by the removal or displacement of lipids, which can result in complex dissociation, non-native conformations, or a strong preference for certain states at the exclusion of others. Here, we will showcase two examples where we use mild membrane protein extraction methods, followed by single-particle cryo-EM to reveal more native high- resolution structural information of membrane protein complexes. (1) P-type ATPases have been structurally characterized as monomers after being extracted from biological membranes using detergents. Here, we use a variety of detergents and polymers to extract and characterize magnesium transporter P-type ATPase MgtA from Escherichia coli and find that the protein exists and functions as a dimer when extracted using mild detergents or polymers. We obtained high-resolution cryo-EM structures of the homodimeric form, which shed light on the dimer interface, ion-binding sites as well as the predicted unstructured N-terminal tail, which is well resolved in our dimeric cryo-EM maps. (2) E. coli MscS, a model system for MSC gating, is an inner membrane protein that opens when external osmolarity changes cause water influx and stretches the membrane. The efflux of osmolytes through these channels reduces the osmotic gradient and prevents cell lysis, enabling bacteria to colonize osmotically challenging host environments and survive transmission through fresh water. As a tension sensor, MscS is very sensitive and highly adaptive. It readily opens under super-threshold tension and closes upon tension reduction, but under lower tensions, it slowly inactivates and can only recover after tension release. Existing cryo-EM structures do not explain the entire functional gating cycle of open, closed, and inactivated states. A central question in the field has been the assignment of the frequently observed non-conductive conformation to either a closed or inactivated state. Here, we solved a 3 Å cryo-EM structure of MscS in native nanodiscs obtained via extraction with the novel Glyco- DIBMA polymer, eliminating the detergent solubilization and lipid removal step common to all prior structures. We observe densities of endogenous phospholipids between the transmembrane helices, stabilized by electrostatics interactions. Through mutations we examine the functional effects of their destabilization, illustrating a novel lipid-mediated inactivation mechanism based on an uncoupling of the peripheral tension- sensing helices from the gate. The use of this polymer increased the predictive power of our cryo-EM structure, allowing us to associate the solved conformation with the inactivated state of the multi-state MSC MscS.

  PublisherDOI

• Fluorescent peptides for membrane tension and domain structure reporting

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-12-31

  articleOpen accessSenior authorCorresponding

  venom. Previously, we have shown that amphipathic GsMTx4 binds to lipids and inhibits mechanosensitive channels by inserting more deeply into the membrane at tensions near activation thresholds, thereby acting as a buffer clamping lateral pressure in the bilayer. We leverage this property of GsMTx4 to redistribute between the 'shallow' and 'deep' immersion states, thereby designing probes with a fluorescent moiety that increases quantum yield in nonpolar environments. GsMTx4 analogs carrying fluorescent groups at the two positions increase fluorescence intensity in osmotically shocked liposomes and aspirated giant vesicles in a near-linear fashion in response to physiological bilayer tensions. The responses show dependence on membrane composition, particularly lipid charge and the presence of lipid-ordering components, such as sphingomyelin and cholesterol. Langmuir compression isotherms recorded in the presence of NBD analogs indicated initial incorporation into the monolayer, followed by sharp expulsion at the monolayer-bilayer equivalence pressure, with correlated changes in monolayer compressibility and fluorescence, illustrating the basic principle of probe action. The probes show promise for monitoring tension in biological membranes at low, non-inhibitory concentrations. Experiments with native cell-derived membrane vesicles reveal heterogeneous baseline staining and tension responses, underscoring the probes' selectivity for distinct membrane domains. Significance: Cell mechanics are crucial for all cell functions, including division, survival, migration, and differentiation. Although many versions of fluorescent linear force sensors have been developed for cytoskeletal and ECM elements, few tools exist to monitor two-dimensional tension in cell membranes. Many cells are motile, actively deforming their membrane, supported and driven by the underlying cytoskeleton. There is a two-order-of-magnitude discrepancy between membrane tension estimates from the tether formation technique and the tensions that activate common mechanosensitive channels in most cells. This discrepancy highlights the need for non-invasive membrane probes that can independently measure membrane tension, especially since it can be highly localized and dynamic. Here, we introduce such probes and a new principle for tension measurement.

  PublisherOA PDFDOI

• Thermodynamics of arginine interactions with organic phosphates

  Biophysical Journal · 2025-05-20 · 2 citations

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  PublisherDOI

Recent grants

• The bacterial mechanosentitive channel as a multimodal sensor device

  NIH · $1.1M · 2013–2018

• A Comprehensive approach to bacterial osmotolerance

  NIH · $2.2M · 2018–2025

• NIH Grant R01NS039314

  NIH · $2.3M · 2011

• NIH Grant R01GM075225

  NIH · $1.1M · 2010

Frequent coauthors

• Andriy Anishkin

  University of Maryland, College Park

  83 shared

• Leonid Chernomordik

  Institute of Neuroimmunology of the Slovak Academy of Sciences

  23 shared

• Madolyn Britt

  University of Maryland, College Park

  22 shared

• Elissa Moller

  20 shared

• Vadim A. Klenchin

  University of Wisconsin–Madison

  18 shared

• Uğur Çetiner

  18 shared

• Kishore Kamaraju

  University of Maryland, College Park

  17 shared

• Ian Rowe

  University of Maryland, College Park

  17 shared

Education

• Ph.D., Biology

  Moscow State University

Awards & honors

• J. W. Ritter Award (1988)
• University of Maryland, College of Life Sciences Junior Facu…