TY - JOUR
T1 - Computational Dissection of Membrane Transport at a Microscopic Level
AU - Jiang, Tao
AU - Wen, Po Chao
AU - Trebesch, Noah
AU - Zhao, Zhiyu
AU - Pant, Shashank
AU - Kapoor, Karan
AU - Shekhar, Mrinal
AU - Tajkhorshid, Emad
N1 - Funding Information:
The authors acknowledge support by the National Institutes of Health under award numbers P41-GM104601 (to E.T.) and R01-GM123455 (to E.T.), the National Science Foundation Graduate Research Fellowship Program under Grant No. 1746047 (to N.T.), and the Beckman Institute Graduate Fellowship (to S.P.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health and the National Science Foundation. We also acknowledge computing resources provided by Blue Waters at National Center for Supercomputing Applications, and Extreme Science and Engineering Discovery Environment (grant MCA06N060 to E.T.).
Funding Information:
The authors acknowledge support by the National Institutes of Health under award numbers P41-GM104601 (to E.T.) and R01-GM123455 (to E.T.), the National Science Foundation Graduate Research Fellowship Program under Grant No. 1746047 (to N.T.), and the Beckman Institute Graduate Fellowship (to S.P.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health and the National Science Foundation. We also acknowledge computing resources provided by Blue Waters at National Center for Supercomputing Applications, and Extreme Science and Engineering Discovery Environment (grant MCA06N060 to E.T.). Cholesterol a lipid component that appears in eukaryotic membranes exclusively. It is believed to cluster with itself and sphingolipids, thereby locally rigidifying the membrane into a gel phase in contrast to the fluid, cholesterol-free phase of the membrane. The formation of cholesterol-rich microdomains influences the localization and functional regulation of many membrane proteins. Coarse-grained (CG) methods simplifiy simulation systems using reduced representations that typically represent a group of atoms with one interaction site, instead of individual atoms as in all-atom MD, thereby allowing the construction and simulation of very large systems and the study of long-term dynamics efficiently. Since the reduced representations in CG models lack chemical detail, their structural and energetic accuracy is sacrificed to trade for the computational efficiency. Cryo-electron microscopy (cryo-EM) observes molecular structures using a transmission electron microscope under cryogenic conditions. Recent development in single-particle cryo-EM allows structural determination at near-atomic resolutions for large biomolecular and cellular systems. Enhanced sampling methods are often used to address the insufficient timescale of conventional (unbiased) MD at describing the functional dynamics of biomolecules. The approaches of enhanced sampling typically involve a structural and thermodynamic characterization of a process along a specific pathway (defined by reaction coordinate). Force field in MD, refers to the parameters describing the interactions between atoms or simulation particles. Typically, parameters of an all-atom force field consist of bonded terms (including bond stretching, bond angles, and torsional angles) as well as nonbonded terms (van der Waals and electrostatic interactions). Hydrogen–deuterium exchange mass spectrometry (HDX-MS) probes solvent accessibility of protein residues by measuring the exchange rate between polar protons of the protein and the deuterium of heavy water using protein mass spectrometry. Molecular dynamics (MD) a physics-based method to simulate the thermal fluctuations and movements in molecular systems. The simulated molecules are presented in structural models that are composed of individual atoms and their interactions are defined in the force field. Usually, MD simulations are carried out under equilibrium (unbiased) conditions, however, additional forces (biases) can be introduced for thermodynamic and/or kinetic characterizations. Reaction coordinate the abstraction of the changes that occurred during a process, usually mapped onto geometrical features of the molecular systems, which is used to represent the transition pathway associated with the process. For example, the distance between a substrate and its binding site residues can be used as a reaction coordinate for the substrate unbinding process. Conversely, the relative orientation of two major structural domains in a transporter can be used to map its global conformational change during the transport cycle. X-ray crystallography determines structures of biological molecules by resolving the X-ray defraction patterns from crystals of purified samples.
Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2020/3
Y1 - 2020/3
N2 - Membrane transporters are key gatekeeper proteins at cellular membranes that closely control the traffic of materials. Their function relies on structural rearrangements of varying degrees that facilitate substrate translocation across the membrane. Characterizing these functionally important molecular events at a microscopic level is key to our understanding of membrane transport, yet challenging to achieve experimentally. Recent advances in simulation technology and computing power have rendered molecular dynamics (MD) simulation a powerful biophysical tool to investigate a wide range of dynamical events spanning multiple spatial and temporal scales. Here, we review recent studies of diverse membrane transporters using computational methods, with an emphasis on highlighting the technical challenges, key lessons learned, and new opportunities to illuminate transporter structure and function.
AB - Membrane transporters are key gatekeeper proteins at cellular membranes that closely control the traffic of materials. Their function relies on structural rearrangements of varying degrees that facilitate substrate translocation across the membrane. Characterizing these functionally important molecular events at a microscopic level is key to our understanding of membrane transport, yet challenging to achieve experimentally. Recent advances in simulation technology and computing power have rendered molecular dynamics (MD) simulation a powerful biophysical tool to investigate a wide range of dynamical events spanning multiple spatial and temporal scales. Here, we review recent studies of diverse membrane transporters using computational methods, with an emphasis on highlighting the technical challenges, key lessons learned, and new opportunities to illuminate transporter structure and function.
KW - conformational change
KW - drug target
KW - free energy calculation
KW - lipid–protein interaction
KW - membrane transporter
KW - molecular dynamics simulation
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U2 - 10.1016/j.tibs.2019.09.001
DO - 10.1016/j.tibs.2019.09.001
M3 - Review article
C2 - 31813734
AN - SCOPUS:85076251060
SN - 0968-0004
VL - 45
SP - 202
EP - 216
JO - Trends in Biochemical Sciences
JF - Trends in Biochemical Sciences
IS - 3
ER -