scholarly journals Crowding-induced opening of the mechanosensitive Piezo1 channel in silico

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Wenjuan Jiang ◽  
John Smith Del Rosario ◽  
Wesley Botello-Smith ◽  
Siyuan Zhao ◽  
Yi-chun Lin ◽  
...  
Keyword(s):  
Binding Sites ◽  
Ion Permeation ◽  
Channel Activity ◽  
Bending Rigidity ◽  
Hyperbolic Tangent ◽  
Ionic Selectivity ◽  
Potential Binding ◽  
Activation Gate ◽  
Dynamics Simulations ◽  
Mutant Phenotypes

AbstractMechanosensitive Piezo1 channels are essential mechanotransduction proteins in eukaryotes. Their curved transmembrane domains, called arms, create a convex membrane deformation, or footprint, which is predicted to flatten in response to increased membrane tension. Here, using a hyperbolic tangent model, we show that, due to the intrinsic bending rigidity of the membrane, the overlap of neighboring Piezo1 footprints produces a flattening of the Piezo1 footprints and arms. Multiple all-atom molecular dynamics simulations of Piezo1 further reveal that this tension-independent flattening is accompanied by gating motions that open an activation gate in the pore. This open state recapitulates experimentally obtained ionic selectivity, unitary conductance, and mutant phenotypes. Tracking ion permeation along the open pore reveals the presence of intracellular and extracellular fenestrations acting as cation-selective sites. Simulations also reveal multiple potential binding sites for phosphatidylinositol 4,5-bisphosphate. We propose that the overlap of Piezo channel footprints may act as a cooperative mechanism to regulate channel activity.

scholarly journals A Piezo1 Open State Reveals a Multi-fenestrated Ion Permeation Pathway

2020 ◽  
Author(s):  
Wenjuan Jiang ◽  
John Smith Del Rosario ◽  
Wesley Botello-Smith ◽  
Siyuan Zhao ◽  
Yi-chun Lin ◽  
...  
Keyword(s):  
Membrane Lipids ◽  
Boundary Effect ◽  
Experimental Studies ◽  
Ion Permeation ◽  
Ion Diffusion ◽  
Ionic Selectivity ◽  
Electrophysiological Characterization ◽  
Dynamics Simulations ◽  
Mutant Phenotypes

ABSTRACTForce-sensing Piezo channels are essential to many aspects of vertebrate physiology. Activation of Piezo1 is facilitated by the presence of negative membrane lipids in the inner leaflet, such as phosphatidylinositol-4,5-bisphosphate (PIP2). Here, to study how Piezo1 opens, we performed molecular dynamics simulations of Piezo1 in membranes flattened by the periodic boundary effect and with or without PIP2 lipids. The Piezo1 pore spontaneously opens in the asymmetrical bilayer but not in the symmetric membrane or when PIP2 lipids are neutralized. Electrophysiological characterization of putative PIP2-interacting Piezo1 residues suggests the contribution of multiple PIP2 binding sites. Our Piezo1 open state recapitulates ionic selectivity, unitary conductance and mutant phenotypes obtained from numerous experimental studies. Tracking ion diffusion through the open pore reveals the presence of intracellular and extracellular fenestrations, delineating a multi-fenestrated permeation pathway. This open state sheds light on the mechanisms of lipid modulation, permeation, and selectivity in a Piezo channel.

scholarly journals Desensitization of Mouse Nicotinic Acetylcholine Receptor Channels

1998 ◽  
Vol 112 (2) ◽  
pp. 181-197 ◽  
Author(s):  
Anthony Auerbach ◽  
Gustav Akk
Keyword(s):  
Acetylcholine Receptor ◽  
Rate Constant ◽  
Binding Sites ◽  
Single Channel ◽  
Ion Permeation ◽  
Activation Gate ◽  
The Status ◽  
Single Channel Currents ◽  
Cyclic Models ◽  
Channel Currents

The rate constants of acetylcholine receptor channels (AChR) desensitization and recovery were estimated from the durations and frequencies of clusters of single-channel currents. Diliganded-open AChR desensitize much faster than either unliganded- or diliganded-closed AChR, which indicates that the desensitization rate constant depends on the status of the activation gate rather than the occupancy of the transmitter binding sites. The desensitization rate constant does not change with the nature of the agonist, the membrane potential, the species of permeant cation, channel block by ACh, the subunit composition (ε or γ), or several mutations that are near the transmitter binding sites. The results are discussed in terms of cyclic models of AChR activation, desensitization, and recovery. In particular, a mechanism by which activation and desensitization are mediated by two distinct, but interrelated, gates in the ion permeation pathway is proposed.

scholarly journals Chemistry of cation hydration and conduction in a skeletal muscle ryanodine receptor

2019 ◽  
Author(s):  
Zhaolong Wu ◽  
Congcong Liu ◽  
Hua Yu ◽  
Duan Kang ◽  
Yinping Ma ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Binding Sites ◽  
Ryanodine Receptors ◽  
Cation Binding ◽  
Water Molecules ◽  
Ion Permeation ◽  
Multiscale Dynamics ◽  
Hydration Shells ◽  
Cation Hydration ◽  
Dynamics Simulations

AbstractRyanodine receptors (RyRs) are Ca2+-regulated Ca2+ channels of 2.2-megadalton in muscles and neurons for calcium signaling. How Ca2+ regulates ion conduction in the RyR channels remains elusive. We determined a 2.6-Å cryo-EM structure of rabbit skeletal muscle RyR1, and used multiscale dynamics simulations to elucidate cation interactions with RyR1. We investigated 21 potential cation-binding sites that may together rationalize biphasic Ca2+ response of RyR1. The selectivity filter captures a cation hydration complex by hydrogen-bonding with both the inner and outer hydration shells of water molecules. Molecular dynamics simulations suggest that adjacent Ca2+ ions moving in concert along ion-permeation pathway are separated by at least two cation-binding sites. Our analysis reveals that RyR1 has been evolved to favor its interactions with two hydration shells of cations.

scholarly journals On the dynamics of some small structural motifs in rRNA upon ligand binding

2008 ◽  
Vol 73 (1) ◽  
pp. 41-53
Author(s):  
Aleksandra Rakic ◽  
Petar Mitrasinovic
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Binding Sites ◽  
De Novo ◽  
Reference Structure ◽  
Base Pairs ◽  
Rna Sequences ◽  
Conformational Model ◽  
Thermodynamic Variables ◽  
Dynamics Simulations

The present study characterizes using molecular dynamics simulations the behavior of the GAA (1186-1188) hairpin triloops with their closing c-g base pairs in large ribonucleoligand complexes (PDB IDs: 1njn, 1nwy, 1jzx). The relative energies of the motifs in the complexes with respect to that in the reference structure (unbound form of rRNA; PDB ID: 1njp) display the trends that agree with those of the conformational parameters reported in a previous study1 utilizing the de novo pseudotorsional (?,?) approach. The RNA regions around the actual RNA-ligand contacts, which experience the most substantial conformational changes upon formation of the complexes were identified. The thermodynamic parameters, based on a two-state conformational model of RNA sequences containing 15, 21 and 27 nucleotides in the immediate vicinity of the particular binding sites, were evaluated. From a more structural standpoint, the strain of a triloop, being far from the specific contacts and interacting primarily with other parts of the ribosome, was established as a structural feature which conforms to the trend of the average values of the thermodynamic variables corresponding to the three motifs defined by the 15-, 21- and 27-nucleotide sequences. From a more functional standpoint, RNA-ligand recognition is suggested to be presumably dictated by the types of ligands in the complexes.

scholarly journals Connecting Structure with Kinetics of Single-Stranded DNA Fluctuations that Provide Potential Binding Sites for Replication Proteins

2021 ◽  
Vol 120 (3) ◽  
pp. 219a
Author(s):  
Claire Albrecht ◽  
Brett A. Israels ◽  
Chloe Chvatal ◽  
Peter H. von Hippel ◽  
Andrew H. Marcus
Keyword(s):  
Binding Sites ◽  
Replication Proteins ◽  
Single Stranded Dna ◽  
Potential Binding ◽  
Kinetics Of

scholarly journals An In-Silico Study of Stable and Environment-Friendly Oryza sativa Urease

2020 ◽  
Vol 11 (3) ◽  
pp. 10238-10247
Keyword(s):  
Oryza Sativa ◽  
Binding Sites ◽  
3D Structure ◽  
Crop Productivity ◽  
Environment Friendly ◽  
Potential Binding ◽  
Urease Enzyme ◽  
In Silico Study ◽  
Stable Mutant ◽  
Detrimental Impact

Urea is one of the most extensively used fertilizers in agriculture but has a detrimental impact on the environment. One of the strategies to reduce this impact can be engineering modified plants containing urease enzyme with a considerably higher affinity for urea so that the urea applied in the fields can be significantly reduced. In this study, we have selected Oryza sativa Urease and generated stable mutants having a high affinity for urea. We modeled the 3D structure of the enzyme and identified the potential binding sites by analyzing the binding sites of similar proteins, i.e., 48 urea binding proteins. We found that mutation of Arg578 with Cys near the substrate-binding site of Oryza sativa Urease leads to a stable mutant protein that has a higher binding affinity for urea. This study will lead to a generation of environment-friendly, stable, genetically modified rice crop that consumes lesser urea, without compromising with crop productivity.

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