Voltage-dependent structural models of the human Hv1 proton channel from long-timescale molecular dynamics simulations

The voltage-gated Hv1 proton channel is a ubiquitous membrane protein that has roles in a variety of cellular processes, including proton extrusion, pH regulation, production of reactive oxygen species, proliferation of cancer cells, and increased brain damage during ischemic stroke. A crystal structure of an Hv1 construct in a putative closed state has been reported, and structural models for the channel open state have been proposed, but a complete characterization of the Hv1 conformational dynamics under an applied membrane potential has been elusive. We report structural models of the Hv1 voltage-sensing domain (VSD), both in a hyperpolarized state and a depolarized state resulting from voltage-dependent conformational changes during a 10-μs-timescale atomistic molecular dynamics simulation in an explicit membrane environment. In response to a depolarizing membrane potential, the S4 helix undergoes an outward displacement, leading to changes in the VSD internal salt-bridge network, resulting in a reshaping of the permeation pathway and a significant increase in hydrogen bond connectivity throughout the channel. The total gating charge displacement associated with this transition is consistent with experimental estimates. Molecular docking calculations confirm the proposed mechanism for the inhibitory action of 2-guanidinobenzimidazole (2GBI) derived from electrophysiological measurements and mutagenesis. The depolarized structural model is also consistent with the formation of a metal bridge between residues located in the core of the VSD. Taken together, our results suggest that these structural models are representative of the closed and open states of the Hv1 channel.

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Constant pH Molecular Dynamics Reveals How Proton Release Drives the Conformational Transition of a Transmembrane Efflux Pump

10.26434/chemrxiv.5496907 ◽

2017 ◽

Author(s):

Jana Shen ◽

Zhi Yue ◽

Helen Zgurskaya ◽

Wei Chen

Keyword(s):

Molecular Dynamics ◽

Conformational Changes ◽

Transmembrane Domain ◽

Conformational Transition ◽

Conformational Dynamics ◽

Proton Release ◽

Intrinsic Resistance ◽

Constant Ph ◽

Wide Range ◽

Constant Ph Molecular Dynamics

AcrB is the inner-membrane transporter of E. coli AcrAB-TolC tripartite efflux complex, which plays a major role in the intrinsic resistance to clinically important antibiotics. AcrB pumps a wide range of toxic substrates by utilizing the proton gradient between periplasm and cytoplasm. Crystal structures of AcrB revealed three distinct conformational states of the transport cycle, substrate access, binding and extrusion, or loose (L), tight (T) and open (O) states. However, the specific residue(s) responsible for proton binding/release and the mechanism of proton-coupled conformational cycling remain controversial. Here we use the newly developed membrane hybrid-solvent continuous constant pH molecular dynamics technique to explore the protonation states and conformational dynamics of the transmembrane domain of AcrB. Simulations show that both Asp407 and Asp408 are deprotonated in the L/T states, while only Asp408 is protonated in the O state. Remarkably, release of a proton from Asp408 in the O state results in large conformational changes, such as the lateral and vertical movement of transmembrane helices as well as the salt-bridge formation between Asp408 and Lys940 and other sidechain rearrangements among essential residues.Consistent with the crystallographic differences between the O and L protomers, simulations offer dynamic details of how proton release drives the O-to-L transition in AcrB and address the controversy regarding the proton/drug stoichiometry. This work offers a significant step towards characterizing the complete cycle of proton-coupled drug transport in AcrB and further validates the membrane hybrid-solvent CpHMD technique for studies of proton-coupled transmembrane proteins which are currently poorly understood.

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Molecular Basis of Glucose Transport Mechanism in Plants

10.26434/chemrxiv.8049848.v1 ◽

2019 ◽

Cited By ~ 2

Author(s):

Balaji Selvam ◽

Ya-Chi Yu ◽

Liqing Chen ◽

Diwakar Shukla

Keyword(s):

Molecular Dynamics ◽

Free Energy ◽

Molecular Dynamics Simulations ◽

Conformational Changes ◽

Transport Mechanism ◽

Conformational Dynamics ◽

Site Directed Mutagenesis ◽

Free Energy Barrier ◽

Transport Cycle ◽

Dynamics Simulations

The SWEET family belongs to a class of transporters in plants that undergoes large conformational changes to facilitate transport of sugar molecules across the cell membrane. However, the structures of their functionally relevant conformational states in the transport cycle have not been reported. In this study, we have characterized the conformational dynamics and complete transport cycle of glucose in OsSWEET2b transporter using extensive molecular dynamics simulations. Using Markov state models, we estimated the free energy barrier associated with different states as well as 1 for the glucose the transport mechanism. SWEETs undergoes structural transition to outward-facing (OF), Occluded (OC) and inward-facing (IF) and strongly support alternate access transport mechanism. The glucose diffuses freely from outside to inside the cell without causing major conformational changes which means that the conformations of glucose unbound and bound snapshots are exactly same for OF, OC and IF states. We identified a network of hydrophobic core residues at the center of the transporter that restricts the glucose entry to the cytoplasmic side and act as an intracellular hydrophobic gate. The mechanistic predictions from molecular dynamics simulations are validated using site-directed mutagenesis experiments. Our simulation also revealed hourglass like intermediate states making the pore radius narrower at the center. This work provides new fundamental insights into how substrate-transporter interactions actively change the free energy landscape of the transport cycle to facilitate enhanced transport activity.

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Conformational dynamics and membrane interactions of the E. coli outer membrane protein FecA: A molecular dynamics simulation study

Biochimica et Biophysica Acta (BBA) - Biomembranes ◽

10.1016/j.bbamem.2012.08.021 ◽

2013 ◽

Vol 1828 (2) ◽

pp. 284-293 ◽

Cited By ~ 41

Author(s):

Thomas J. Piggot ◽

Daniel A. Holdbrook ◽

Syma Khalid

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Membrane Protein ◽

Outer Membrane ◽

Simulation Study ◽

Outer Membrane Protein ◽

Conformational Dynamics ◽

Dynamics Simulation ◽

Membrane Interactions ◽

E Coli

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THE "FOLDING" BEHAVIORS OF HOMOPOLYMERS WITH ONE END FIXED

International Journal of Modern Physics B ◽

10.1142/s0217979204025294 ◽

2004 ◽

Vol 18 (15) ◽

pp. 2123-2139 ◽

Cited By ~ 4

Author(s):

BIN XUE ◽

JUN WANG ◽

WEI WANG

Keyword(s):

Molecular Dynamics ◽

Chain Length ◽

Conformational Changes ◽

Canonical Ensemble ◽

Interaction Strength ◽

Simulation Method ◽

Dynamics Simulation ◽

Radius Of Gyration ◽

Native Conformation ◽

Collapse Temperature

We study the "folding" behaviors of homopolymers with one end fixed. By using canonical ensemble molecular dynamics simulation method, we observe the conformational changes during folding processes. Long chains collapse to the helical nuclei, then regroup to helix from the free-end to form the compact conformations through the middle stages of helix-like coil and helix-like cone, while short chains do not apparently have the above mentioned middle stages. Through simulated annealing, the native conformation of homopolymer chain in our model is found to be helix. We show the relations between specific heat C v (T) and radius of gyration R g (T) as functions of temperature, chain length and the interaction strength, respectively. We find that these two quantities match well and can be combined to interpret the "folding" process of the homopolymer. It is found that the collapse temperature Tθ and the native-like folding temperature T f do not change with the chain length in our model, however the interaction strength affects the values of Tθ and T f .

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Conformational dynamics in bulk polyethylene: A molecular dynamics simulation study

The Journal of Chemical Physics ◽

10.1063/1.468134 ◽

1994 ◽

Vol 101 (1) ◽

pp. 788-797 ◽

Cited By ~ 104

Author(s):

Richard H. Boyd ◽

Richard H. Gee ◽

Jie Han ◽

Yong Jin

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Simulation Study ◽

Conformational Dynamics ◽

Dynamics Simulation

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S09A2 Conformational changes in F1-ATPase: Molecular dynamics simulation study(Mechanism of F_1-ATPase Molecular Motor-A Cross Talk among Single Molecule, Structural Biology, and Molecular Simulation Studies-)

Seibutsu Butsuri ◽

10.2142/biophys.47.s13_1 ◽

2007 ◽

Vol 47 (supplement) ◽

pp. S13

Author(s):

Mitsunori Ikeguchi

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Structural Biology ◽

Single Molecule ◽

Conformational Changes ◽

Simulation Study ◽

Molecular Motor ◽

Dynamics Simulation ◽

Simulation Studies ◽

F1 Atpase

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Comparison of the effect of poly(N-vinyl caprolactam) and poly(N-isopropyl acrylamide) trimers on the stability of hydrated Na-montmorillonite: A molecular dynamics study

Polymers and Polymer Composites ◽

10.1177/0967391120935249 ◽

2020 ◽

pp. 096739112093524

Author(s):

Jiafang Xu ◽

Moussa Camara ◽

Hualin Liao ◽

Hong Guo ◽

Kouassi Louis Kra ◽

...

Keyword(s):

Molecular Dynamics ◽

Conformational Changes ◽

Stable State ◽

Dynamics Simulation ◽

Effect Of Temperature ◽

Radius Of Gyration ◽

Molecular Arrangement ◽

Isopropyl Acrylamide ◽

The Stability ◽

The Impact

In the present study, we performed a molecular dynamics simulation of the intercalation of poly( N-isopropyl acrylamide) (NIPAM)3 and poly( N-vinyl caprolactam) (NVCL)3 trimers into Na-montmorillonite (Na-Mt) to evaluate their effects on the interlayer structure and the stability of hydrated Na-Mt. The impact of both trimers on the interlayer species and their dynamics properties at different temperatures in a canonical ensemble (NVT) were investigated. The results showed that the electrostatic forces exerted by Na cations on H2O molecules and the interlayer H2O molecular arrangement are not affected by the rise in temperature after adding both trimers. Trimer addition reinforced the structure of interlayer H2O molecules so that the effect of temperature increase on them became negligible. The structural dynamics evolution of the radius of gyration of both trimers showed the existence of conformation changes when temperature increased. These conformational changes are more complex in the case of (NVCL)3 than (NIPAM)3 due to its large monomers. Both trimers reduced the mobility of interlayer particles with a better inhibition effect obtained for (NVCL)3 compared to (NIPAM)3. The concentration profile of interlayers’ species showed the affinity of Na cations for clay mineral surfaces while H2O molecules moved away. Compared these two trimers, the most stable state of Na-Mt is achieved with (NVCL)3. These results could help highlight the inhibition properties of (NIPAM)3 and (NVCL)3 on hydrated Na-Mt and to predict its stability against changes in environmental conditions.

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