1
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Huang Y, Chandran Suja V, Yang M, Malkovskiy AV, Tandon A, Colom A, Qin J, Fuller GG. Interfacial stresses on droplet interface bilayers using two photon fluorescence lifetime imaging microscopy. J Colloid Interface Sci 2024; 653:1196-1204. [PMID: 37793246 DOI: 10.1016/j.jcis.2023.09.092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 09/06/2023] [Accepted: 09/14/2023] [Indexed: 10/06/2023]
Abstract
HYPOTHESIS Response of lipid bilayers to external mechanical stimuli is an active area of research with implications for fundamental and synthetic cell biology. Developing novel tools for systematically imposing mechanical strains and non-invasively mapping out interfacial (membrane) stress distributions on lipid bilayers can accelerate research in this field. EXPERIMENTS We report a miniature platform to manipulate model cell membranes in the form of droplet interface bilayers (DIBs), and non-invasively measure spatio-temporally resolved interfacial stresses using two photon fluorescence lifetime imaging of an interfacially active molecular flipper (Flipper-TR). We established the effectiveness of the developed framework by investigating interfacial stresses accompanying three key processes associated with DIBs: thin film drainage between lipid monolayer coated droplets, bilayer formation, and bilayer separation. FINDINGS The measurements revealed fundamental aspects of DIBs including the existence of a radially decaying interfacial stress distribution post bilayer formation, and the simultaneous build up and decay of stress respectively at the bilayer corner and center during bilayer separation. Finally, utilizing interfacial rheology measurements and MD simulations, we also reveal that the tested molecular flipper is sensitive to membrane fluidity that changes with interfacial stress - expanding the scientific understanding of how molecular flippers sense stress.
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Affiliation(s)
- Yaoqi Huang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Vineeth Chandran Suja
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA; School of Engineering and Applied Sciences, Harvard University, MA - 02138, USA.
| | - Menghao Yang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Andrey V Malkovskiy
- Carnegie Institute for Science, Department of Plant Biology, Stanford CA 94305, USA
| | - Arnuv Tandon
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Adai Colom
- Biofisika Institute (CSIC, UPV/EHU), 48940 Leioa, Spain; Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, Campus Universitario, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain
| | - Jian Qin
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Gerald G Fuller
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
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2
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Nestorovich EM, Bezrukov SM. Beta-Barrel Channel Response to High Electric Fields: Functional Gating or Reversible Denaturation? Int J Mol Sci 2023; 24:16655. [PMID: 38068977 PMCID: PMC10706840 DOI: 10.3390/ijms242316655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 11/16/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
Ion channels exhibit gating behavior, fluctuating between open and closed states, with the transmembrane voltage serving as one of the essential regulators of this process. Voltage gating is a fundamental functional aspect underlying the regulation of ion-selective, mostly α-helical, channels primarily found in excitable cell membranes. In contrast, there exists another group of larger, and less selective, β-barrel channels of a different origin, which are not directly associated with cell excitability. Remarkably, these channels can also undergo closing, or "gating", induced by sufficiently strong electric fields. Once the field is removed, the channels reopen, preserving a memory of the gating process. In this study, we explored the hypothesis that the voltage-induced closure of the β-barrel channels can be seen as a form of reversible protein denaturation by the high electric fields applied in model membranes experiments-typically exceeding twenty million volts per meter-rather than a manifestation of functional gating. Here, we focused on the bacterial outer membrane channel OmpF reconstituted into planar lipid bilayers and analyzed various characteristics of the closing-opening process that support this idea. Specifically, we considered the nearly symmetric response to voltages of both polarities, the presence of multiple closed states, the stabilization of the open conformation in channel clusters, the long-term gating memory, and the Hofmeister effects in closing kinetics. Furthermore, we contemplate the evolutionary aspect of the phenomenon, proposing that the field-induced denaturation of membrane proteins might have served as a starting point for their development into amazing molecular machines such as voltage-gated channels of nerve and muscle cells.
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Affiliation(s)
- Ekaterina M. Nestorovich
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Sergey M. Bezrukov
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA;
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3
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Samineni L, Acharya B, Behera H, Oh H, Kumar M, Chowdhury R. Protein engineering of pores for separation, sensing, and sequencing. Cell Syst 2023; 14:676-691. [PMID: 37591205 DOI: 10.1016/j.cels.2023.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 06/13/2023] [Accepted: 07/19/2023] [Indexed: 08/19/2023]
Abstract
Proteins are critical to cellular function and survival. They are complex molecules with precise structures and chemistries, which allow them to serve diverse functions for maintaining overall cell homeostasis. Since the discovery of the first enzyme in 1833, a gamut of advanced experimental and computational tools has been developed and deployed for understanding protein structure and function. Recent studies have demonstrated the ability to redesign/alter natural proteins for applications in industrial processes of interest and to make customized, novel synthetic proteins in the laboratory through protein engineering. We comprehensively review the successes in engineering pore-forming proteins and correlate the amino acid-level biochemistry of different pore modification strategies to the intended applications limited to nucleotide/peptide sequencing, single-molecule sensing, and precise molecular separations.
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Affiliation(s)
- Laxmicharan Samineni
- Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, TX 78712, USA
| | - Bibek Acharya
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
| | - Harekrushna Behera
- Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, TX 78712, USA
| | - Hyeonji Oh
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712, USA
| | - Manish Kumar
- Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, TX 78712, USA; McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712, USA
| | - Ratul Chowdhury
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA.
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4
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Mayse LA, Movileanu L. Gating of β-Barrel Protein Pores, Porins, and Channels: An Old Problem with New Facets. Int J Mol Sci 2023; 24:12095. [PMID: 37569469 PMCID: PMC10418385 DOI: 10.3390/ijms241512095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/23/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
β barrels are ubiquitous proteins in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. These transmembrane proteins (TMPs) execute a wide variety of tasks. For example, they can serve as transporters, receptors, membrane-bound enzymes, as well as adhesion, structural, and signaling elements. In addition, multimeric β barrels are common structural scaffolds among many pore-forming toxins. Significant progress has been made in understanding the functional, structural, biochemical, and biophysical features of these robust and versatile proteins. One frequently encountered fundamental trait of all β barrels is their voltage-dependent gating. This process consists of reversible or permanent conformational transitions between a large-conductance, highly permeable open state and a low-conductance, solute-restrictive closed state. Several intrinsic molecular mechanisms and environmental factors modulate this universal property of β barrels. This review article outlines the typical signatures of voltage-dependent gating. Moreover, we discuss recent developments leading to a better qualitative understanding of the closure dynamics of these TMPs.
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Affiliation(s)
- Lauren A. Mayse
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244, USA;
- Department of Biomedical and Chemical Engineering, Syracuse University, 223 Link Hall, Syracuse, NY 13244, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244, USA;
- Department of Biomedical and Chemical Engineering, Syracuse University, 223 Link Hall, Syracuse, NY 13244, USA
- The BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
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5
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Ju H, Kim D, Oh YK. Lipid nanoparticle-mediated CRISPR/Cas9 gene editing and metabolic engineering for anticancer immunotherapy. Asian J Pharm Sci 2022; 17:641-652. [DOI: 10.1016/j.ajps.2022.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 05/17/2022] [Accepted: 07/26/2022] [Indexed: 11/30/2022] Open
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6
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Kim D, Wu Y, Shim G, Oh YK. Genome-Editing-Mediated Restructuring of Tumor Immune Microenvironment for Prevention of Metastasis. ACS NANO 2021; 15:17635-17656. [PMID: 34723493 DOI: 10.1021/acsnano.1c05420] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Modulating the tumor immune microenvironment to activate immune cells has been investigated to convert cold to hot tumors. Here, we report that metal-lipid hybrid nanoparticle (MLN)-mediated gene editing of transforming growth factor-β (TGF-β) can restructure the tumor microenvironment to an "immune activated" state for subsequent immunotherapy. MLNs with cationic lipids and elemental metallic Au inside were designed to deliver plasmid DNA encoding TGF-β single guide RNA and Cas9 protein (pC9sTgf) and to convert near-infrared light (NIR) to heat. Upon NIR irradiation, MLNs induced photothermal anticancer effects and calreticulin exposure on B16F10 cancer cells. Lipoplexes of pC9sTgf and MLN (pC9sTgf@MLN) provided gene editing of B16F10 cells and in vivo tumor tissues. In mice treated with pC9sTgf@MLNs and NIR irradiation, the tumor microenvironment showed increases in mature dendritic cells, cytotoxic T cells, and interferon-γ expression. In B16F10 tumor-bearing mice, intratumoral injection of pC9sTgf@MLNs and NIR irradiation resulted in ablation of primary tumors. Application of pC9sTgf@MLNs and NIR irradiation prevented the growth of secondarily challenged B16F10 cells at distant sites and B16F10 lung metastasis. Combined TGF-β gene editing and phototherapy is herein supported as a modality for restructuring the tumor immune microenvironment and preventing tumor recurrence.
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Affiliation(s)
- Dongyoon Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Yina Wu
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Gayong Shim
- School of Systems Biomedical Science, Soongsil University, Seoul 06978, Republic of Korea
| | - Yu-Kyoung Oh
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
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7
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Lee S, Roesel D, Roke S. Imaging Cu 2+ binding to charged phospholipid membranes by high-throughput second harmonic wide-field microscopy. J Chem Phys 2021; 155:184704. [PMID: 34773948 DOI: 10.1063/5.0063362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The interaction of divalent copper ions (Cu2+) with cell membranes is crucial for a variety of physiological processes of cells, such as hormone synthesis and cellular energy production. These interactions would not be possible without membrane hydration. However, the role of water has not received a lot of attention in membrane studies. Here, we use high-throughput wide-field second harmonic (SH) microscopy to study the interaction between Cu2+ and hydrated freestanding Montal-Müller lipid membranes. The symmetric lipid membranes are composed of 1,2-diphytanoyl-sn-glycero-3-phosphocholine and either 1,2-diphytanoyl-sn-glycero-3-phosphate or 1,2-diphytanoyl-sn-glycero-3-phospho L-serine and are brought into contact with divalent Cu2+, which are added to one leaflet while maintaining the ionic strength balance. We observe transient domains of high SH intensity. In these areas, Cu2+ ions bind to the charged head groups, leading to charge neutralization on one side of the membrane. This exposes the ordered water at the non-interacting side of the membrane interface, which can be used to compute the interfacial membrane potential difference. We find that the domains of lipids with phosphatidic acid head groups display a higher interfacial membrane potential than those with phosphatidylserine head groups, which converts into higher dynamic electrostatic free energies and binding constants.
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Affiliation(s)
- Seonwoo Lee
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - David Roesel
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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8
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Guros NB, Balijepalli A, Klauda JB. Microsecond-timescale simulations suggest 5-HT-mediated preactivation of the 5-HT 3A serotonin receptor. Proc Natl Acad Sci U S A 2020; 117:405-414. [PMID: 31871207 PMCID: PMC6955379 DOI: 10.1073/pnas.1908848117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Aided by efforts to improve their speed and efficiency, molecular dynamics (MD) simulations provide an increasingly powerful tool to study the structure-function relationship of pentameric ligand-gated ion channels (pLGICs). However, accurate reporting of the channel state and observation of allosteric regulation by agonist binding with MD remains difficult due to the timescales necessary to equilibrate pLGICs from their artificial and crystalized conformation to a more native, membrane-bound conformation in silico. Here, we perform multiple all-atom MD simulations of the homomeric 5-hydroxytryptamine 3A (5-HT3A) serotonin receptor for 15 to 20 μs to demonstrate that such timescales are critical to observe the equilibration of a pLGIC from its crystalized conformation to a membrane-bound conformation. These timescales, which are an order of magnitude longer than any previous simulation of 5-HT3A, allow us to observe the dynamic binding and unbinding of 5-hydroxytryptamine (5-HT) (i.e., serotonin) to the binding pocket located on the extracellular domain (ECD) and allosteric regulation of the transmembrane domain (TMD) from synergistic 5-HT binding. While these timescales are not long enough to observe complete activation of 5-HT3A, the allosteric regulation of ion gating elements by 5-HT binding is indicative of a preactive state, which provides insight into molecular mechanisms that regulate channel activation from a resting state. This mechanistic insight, enabled by microsecond-timescale MD simulations, will allow a careful examination of the regulation of pLGICs at a molecular level, expanding our understanding of their function and elucidating key structural motifs that can be targeted for therapeutic regulation.
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Affiliation(s)
- Nicholas B Guros
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742
- Biophysics Group, Microsystems and Nanotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Arvind Balijepalli
- Biophysics Group, Microsystems and Nanotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742;
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9
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The Role of Lipid Interactions in Simulations of the α-Hemolysin Ion-Channel-Forming Toxin. Biophys J 2018; 115:1720-1730. [PMID: 30287110 DOI: 10.1016/j.bpj.2018.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 09/04/2018] [Accepted: 09/07/2018] [Indexed: 01/25/2023] Open
Abstract
Molecular dynamics simulations were performed to describe the function of the ion-channel-forming toxin α-hemolysin (αHL) in lipid membranes that were composed of either 1,2-diphytanoyl-sn-glycero-3-phospho-choline or 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-choline. The simulations highlight the importance of lipid type in maintaining αHL structure and function, enabling direct comparison to experiments for biosensing applications. We determined that although the two lipids studied are similar in structure, 1,2-diphytanoyl-sn-glycero-3-phospho-choline membranes better match the hydrophobic thickness of αHL compared to 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-choline membranes. This hydrophobic match is essential to maintaining proper alignment of β-sheet loops at the trans entrance of αHL, which, when disrupted, creates an additional constriction to ion flow that decreases the channel current below experimental values and creates greater variability in channel conductance. Agreement with experiments was further improved with sufficient lipid membrane equilibration and allowed the discrimination of subtle αHL conduction states with lipid type. Finally, we explore the effects of truncating the extramembrane cap of αHL and its role in maintaining proper alignment of αHL in the membrane and channel conductance. Our results demonstrate the essential role of lipid type and lipid-protein interactions in simulations of αHL and will considerably improve the interpretation of experimental data.
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10
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Liu Z, Ghai I, Winterhalter M, Schwaneberg U. Engineering Enhanced Pore Sizes Using FhuA Δ1-160 from E. coli Outer Membrane as Template. ACS Sens 2017; 2:1619-1626. [PMID: 29052976 DOI: 10.1021/acssensors.7b00481] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Biological membranes are the perfect example of a molecular filter using membrane channels to control the permeability of small water-soluble molecules. To allow filtering of larger hydrophilic molecules we started from the known mutant channel FhuA Δ1-160 in which the cork domain closing the channel had been removed. Here we further expand the pore diameter by copying the amino acid sequence of two β-strands in a stepwise manner increasing the total number of β-strands from 22 to 34. The pore size of the respective expanded channel protein was characterized by single-channel conductance. Insertion of additional β-strands increased the pore conductance but also induced more ion current flickering on the millisecond scale. Further, polymer exclusion measurements were performed by analyzing single-channel conductance in the presence of differently sized polyethylene glycol of known polymer random coil radii. The conclusion from channel conductance of small channel penetrating polymers versus larger excluded ones suggested an increase in pore radii from 1.6 nm for FhuA Δ1-160 up to a maximum of about 2.7 nm for +8 β insertion. Integration of more β-strand caused instability of the channel and exclusion of smaller sized polymer. FhuA Δ1-160 + 10 β and FhuA Δ1-160 + 12 β effective radius decreased to 1.4 and 1.3 nm, respectively, showing the limitations of this approach.
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Affiliation(s)
- Zhanzhi Liu
- Institute
of Biotechnology, RWTH Aachen University, Worringer Weg 3, 52074, Aachen, Germany
| | - Ishan Ghai
- Department
of Life Sciences and Chemistry, Jacobs University Bremen, 28719, Bremen, Germany
| | - Mathias Winterhalter
- Department
of Life Sciences and Chemistry, Jacobs University Bremen, 28719, Bremen, Germany
| | - Ulrich Schwaneberg
- Institute
of Biotechnology, RWTH Aachen University, Worringer Weg 3, 52074, Aachen, Germany
- DWI - Leibniz-Institute for Interactive Materials, Forckenbeckstrasse 50, D-52074 Aachen, Germany
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11
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Wolfe AJ, Si W, Zhang Z, Blanden AR, Hsueh YC, Gugel JF, Pham B, Chen M, Loh SN, Rozovsky S, Aksimentiev A, Movileanu L. Quantification of Membrane Protein-Detergent Complex Interactions. J Phys Chem B 2017; 121:10228-10241. [PMID: 29035562 DOI: 10.1021/acs.jpcb.7b08045] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although fundamentally significant in structural, chemical, and membrane biology, the interfacial protein-detergent complex (PDC) interactions have been modestly examined because of the complicated behavior of both detergents and membrane proteins in aqueous phase. Membrane proteins are prone to unproductive aggregation resulting from poor detergent solvation, but the participating forces in this phenomenon remain ambiguous. Here, we show that using rational membrane protein design, targeted chemical modification, and steady-state fluorescence polarization spectroscopy, the detergent desolvation of membrane proteins can be quantitatively evaluated. We demonstrate that depleting the detergent in the sample well produced a two-state transition of membrane proteins between a fully detergent-solvated state and a detergent-desolvated state, the nature of which depended on the interfacial PDC interactions. Using a panel of six membrane proteins of varying hydrophobic topography, structural fingerprint, and charge distribution on the solvent-accessible surface, we provide direct experimental evidence for the contributions of the electrostatic and hydrophobic interactions to the protein solvation properties. Moreover, all-atom molecular dynamics simulations report the major contribution of the hydrophobic forces exerted at the PDC interface. This semiquantitative approach might be extended in the future to include studies of the interfacial PDC interactions of other challenging membrane protein systems of unknown structure. This would have practical importance in protein extraction, solubilization, stabilization, and crystallization.
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Affiliation(s)
- Aaron J Wolfe
- Department of Physics, Syracuse University , 201 Physics Building, Syracuse, New York 13244-1130, United States.,Structural Biology, Biochemistry, and Biophysics Program, Syracuse University , 111 College Place, Syracuse, New York 13244-4100, United States
| | - Wei Si
- Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments and School of Mechanical Engineering, Southeast University , Nanjing 210096, China.,Department of Physics, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Zhengqi Zhang
- Department of Chemistry and Biochemistry, University of Delaware , 136 Brown Laboratory, Newark, Delaware 19716, United States
| | - Adam R Blanden
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University , 4249 Weiskotten Hall, 766 Irving Av., Syracuse, New York 13210, United States
| | - Yi-Ching Hsueh
- Department of Physics, Syracuse University , 201 Physics Building, Syracuse, New York 13244-1130, United States
| | - Jack F Gugel
- Department of Physics, Syracuse University , 201 Physics Building, Syracuse, New York 13244-1130, United States
| | - Bach Pham
- Department of Chemistry, University of Massachusetts , 820 LGRT, 710 North Pleasant Street, Amherst, Massachusetts 01003-9336, United States
| | - Min Chen
- Department of Chemistry, University of Massachusetts , 820 LGRT, 710 North Pleasant Street, Amherst, Massachusetts 01003-9336, United States
| | - Stewart N Loh
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University , 4249 Weiskotten Hall, 766 Irving Av., Syracuse, New York 13210, United States
| | - Sharon Rozovsky
- Department of Chemistry and Biochemistry, University of Delaware , 136 Brown Laboratory, Newark, Delaware 19716, United States
| | - Aleksei Aksimentiev
- Department of Physics, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Liviu Movileanu
- Department of Physics, Syracuse University , 201 Physics Building, Syracuse, New York 13244-1130, United States.,Structural Biology, Biochemistry, and Biophysics Program, Syracuse University , 111 College Place, Syracuse, New York 13244-4100, United States.,Department of Biomedical and Chemical Engineering, Syracuse University , 329 Link Hall, Syracuse, New York 13244, United States
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12
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Mohammad MM, Tomita N, Ohta M, Movileanu L. The Transmembrane Domain of a Bicomponent ABC Transporter Exhibits Channel-Forming Activity. ACS Chem Biol 2016; 11:2506-18. [PMID: 27379442 PMCID: PMC5026576 DOI: 10.1021/acschembio.6b00383] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that expresses two unique forms of lipopolysaccharides (LPSs) on its bacterial surface, the A- and B-bands. The A-band polysaccharides (A-band PSs) are thought to be exported into the periplasm via a bicomponent ATP-binding cassette (ABC) transporter located within the inner membrane. This ABC protein complex consists of the transmembrane (TMD) Wzm and nucleotide-binding (NBD) Wzt domain proteins. Here, we were able to probe ∼1.36 nS-average conductance openings of the Wzm-based protein complex when reconstituted into a lipid membrane buffered by a 200 mM KCl solution, demonstrating the large-conductance, channel-forming ability of the TMDs. In agreement with this finding, transmission electron microscopy (TEM) imaging revealed the ring-shaped structure of the transmembrane Wzm protein complex. As hypothesized, using liposomes, we demonstrated that Wzm interacts with Wzt. Further, the Wzt polypeptide indeed hydrolyzed ATP but exhibited a ∼75% reduction in the ATPase activity when its Walker A domain was deleted. The distribution and average unitary conductance of the TMD Wzm protein complex were altered by the presence of the NBD Wzt protein, confirming the regulatory role of the latter polypeptide. To our knowledge, the large-conductance, channel-like activity of the Wzm protein complex, although often hypothesized, has not previously been demonstrated. These results constitute a platform for future structural, biophysical, and functional explorations of this bicomponent ABC transporter.
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Affiliation(s)
- Mohammad M. Mohammad
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
| | - Noriko Tomita
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Makoto Ohta
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, USA
- The Syracuse Biomaterials Institute, Syracuse University, 121 Link Hall, Syracuse, New York 13244, USA
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13
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Hadi-Alijanvand H, Rouhani M. Journey of poly-nucleotides through OmpF porin. J Phys Chem B 2015; 119:6113-28. [PMID: 25965338 DOI: 10.1021/acs.jpcb.5b00763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OmpF is an abundant porin in many bacteria which attracts attention as a promising biological nanopore for DNA sequencing. We study the interactions of OmpF with pentameric poly-nucleotides (poly-Ns) in silico. The poly-N molecule is forced to translocate through the lumen of OmpF. Subsequently, the structural and dynamical effects of translocation steps on protein and poly-N molecules are explored in detail. The external loops of OmpF are introduced as the main region for discrimination of poly-Ns based on their organic bases. Structural network analyses of OmpF in the presence or absence of poly-Ns characterize special residues in the structural network of porin. These residues pave the way for engineering OmpF protein. The poly-N-specific pattern of OmpF's local conductance is detected in the current study. Computing the potential of mean force for translocation steps, we define the energetic barrier ahead of poly-N to move through OmpF's lumen. We suggest that fast translocation of the examined poly-N molecules through OmpF seems unattainable by small external driving forces. Our computational results suggest some abilities for OmpF porin like OmpF's potential for being used in poly-N sequencing.
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Affiliation(s)
- Hamid Hadi-Alijanvand
- Department of Biological Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, 45137-66731, Iran
| | - Maryam Rouhani
- Department of Biological Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, 45137-66731, Iran
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14
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Aguilella VM, Verdiá-Báguena C, Alcaraz A. Lipid charge regulation of non-specific biological ion channels. Phys Chem Chem Phys 2014; 16:3881-93. [DOI: 10.1039/c3cp54690j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lipid charge regulation effects in different protein–lipid conformations highlight the role of electrostatic interactions in conductance and selectivity of non-specific biological ion channels.
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Affiliation(s)
| | | | - Antonio Alcaraz
- Dept. Physics
- Lab. Molecular Biophysics
- Universitat Jaume I
- 12080 Castellón, Spain
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