1
|
Sokolov S, Zyrina A, Akimov S, Knorre D, Severin F. Toxic Effects of Penetrating Cations. Membranes (Basel) 2023; 13:841. [PMID: 37888013 PMCID: PMC10608470 DOI: 10.3390/membranes13100841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/08/2023] [Accepted: 10/19/2023] [Indexed: 10/28/2023]
Abstract
As mitochondria are negatively charged organelles, penetrating cations are used as parts of chimeric molecules to deliver specific compounds into mitochondria. In other words, they are used as electrophilic carriers for such chemical moieties as antioxidants, dyes, etc., to transfer them inside mitochondria. However, unmodified penetrating cations affect different aspects of cellular physiology as well. In this review, we have attempted to summarise the data about the side effects of commonly used natural (e.g., berberine) and artificial (e.g., tetraphenylphosphonium, rhodamine, methylene blue) penetrating cations on cellular physiology. For instance, it was shown that such types of molecules can (1) facilitate proton transport across membranes; (2) react with redox groups of the respiratory chain; (3) induce DNA damage; (4) interfere with pleiotropic drug resistance; (5) disturb membrane integrity; and (6) inhibit enzymes. Also, the products of the biodegradation of penetrating cations can be toxic. As penetrating cations accumulate in mitochondria, their toxicity is mostly due to mitochondrial damage. Mitochondria from certain types of cancer cells appear to be especially sensitive to penetrating cations. Here, we discuss the molecular mechanisms of the toxic effects and the anti-cancer activity of penetrating cations.
Collapse
Affiliation(s)
- Svyatoslav Sokolov
- Department of Molecular Energetics of Microorganisms, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1–40 Leninskie Gory, 119991 Moscow, Russia; (S.S.); (D.K.)
| | - Anna Zyrina
- Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products of Russian Academy of Sciences, Premises 8, Bldg. 1, Village of Institute of Poliomyelitis, Settlement “Moskovskiy”, 108819 Moscow, Russia;
| | - Sergey Akimov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 LeninskiyProspekt, 119071 Moscow, Russia;
| | - Dmitry Knorre
- Department of Molecular Energetics of Microorganisms, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1–40 Leninskie Gory, 119991 Moscow, Russia; (S.S.); (D.K.)
| | - Fedor Severin
- Department of Molecular Energetics of Microorganisms, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1–40 Leninskie Gory, 119991 Moscow, Russia; (S.S.); (D.K.)
| |
Collapse
|
2
|
Abhinav, Jurkiewicz P, Hof M, Allolio C, Sýkora J. Modulation of Anionic Lipid Bilayers by Specific Interplay of Protons and Calcium Ions. Biomolecules 2022; 12. [PMID: 36551322 DOI: 10.3390/biom12121894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 12/07/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
Biomembranes, important building blocks of living organisms, are often exposed to large local fluctuations of pH and ionic strength. To capture changes in the membrane organization under such harsh conditions, we investigated the mobility and hydration of zwitterionic and anionic lipid bilayers upon elevated H3O+ and Ca2+ content by the time-dependent fluorescence shift (TDFS) technique. While the zwitterionic bilayers remain inert to lower pH and increased calcium concentrations, anionic membranes are responsive. Specifically, both bilayers enriched in phosphatidylserine (PS) and phosphatidylglycerol (PG) become dehydrated and rigidified at pH 4.0 compared to at pH 7.0. However, their reaction to the gradual Ca2+ increase in the acidic environment differs. While the PG bilayers exhibit strong rehydration and mild loosening of the carbonyl region, restoring membrane properties to those observed at pH 7.0, the PS bilayers remain dehydrated with minor bilayer stiffening. Molecular dynamics (MD) simulations support the strong binding of H3O+ to both PS and PG. Compared to PS, PG exhibits a weaker binding of Ca2+ also at a low pH.
Collapse
|
3
|
Basham CM, Spittle S, Sangoro J, El-Beyrouthy J, Freeman E, Sarles SA. Entrapment and Voltage-Driven Reorganization of Hydrophobic Nanoparticles in Planar Phospholipid Bilayers. ACS Appl Mater Interfaces 2022; 14:54558-54571. [PMID: 36459500 DOI: 10.1021/acsami.2c16677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Engineered nanoparticles (NPs) possess diverse physical and chemical properties, which make them attractive agents for targeted cellular interactions within the human body. Once affiliated with the plasma membrane, NPs can become embedded within its hydrophobic core, which can limit the intended therapeutic functionality and affect the associated toxicity. As such, understanding the physical effects of embedded NPs on a plasma membrane is critical to understanding their design and clinical use. Here, we demonstrate that functionalized, hydrophobic gold NPs dissolved in oil can be directly trapped within the hydrophobic interior of a phospholipid membrane assembled using the droplet interface bilayer technique. This approach to model membrane formation preserves lateral lipid diffusion found in cell membranes and permits simultaneous imaging and electrophysiology to study the effects of embedded NPs on the electromechanical properties of the bilayer. We show that trapped NPs enhance ion conductance and lateral membrane tension in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) bilayers while lowering the adhesive energy of the joined droplets. Embedded NPs also cause changes in bilayer capacitance and area in response to applied voltage, which are nonmonotonic for DOPC bilayers. This electrophysical characterization can reveal NP entrapment without relying on changes in membrane thickness. By evaluating the energetic components of membrane tension under an applied potential, we demonstrate that these nonmonotonic, voltage-dependent responses are caused by reversible clustering of NPs within the unsaturated DOPC membrane core; aggregates form spontaneously at low voltages and are dispersed by higher transmembrane potentials of magnitude similar to those found in the cellular environment. These findings allow for a better understanding of lipid-dependent NP interactions, while providing a platform to study relationships between other hydrophobic nanomaterials and organic membranes.
Collapse
Affiliation(s)
- Colin M Basham
- Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Stephanie Spittle
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Joshua Sangoro
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Joyce El-Beyrouthy
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, Georgia30602, United States
| | - Eric Freeman
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, Georgia30602, United States
| | - Stephen A Sarles
- Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| |
Collapse
|
4
|
Chi S, Zuo M, Zhu M, Wang Z, Liu Z. Loading Drugs in Natural Phospholipid Bilayers of Cell Membrane Shells to Construct Biomimetic Nanocomposites for Enhanced Tumor Therapy. ACS Appl Mater Interfaces 2022; 14:28671-28682. [PMID: 35703029 DOI: 10.1021/acsami.2c08587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Drug-based oncotherapy is seriously challenged by insufficient drug accumulation at tumor sites, mainly resulting from low drug loading efficiency and poor tumor-targeting ability of drug carriers. We herein proposed a "one-stone, two-bird" strategy to circumvent both obstacles, utilizing the source cancer cell membrane (CM) as a dual-function carrier to simultaneously achieve sufficient drug loading and homologous tumor targeting. Combining the use of TPGS (d-α-tocopherol polyethylene glycol 1000 succinate) to inhibit the drug efflux process of drug-resistant tumor, we constructed core-shell-structured nanocomposites CMGNPs consisting of ICG (indocyanine green)/DOX (doxorubicin)-loaded, TPGS/OA (oleic acid)-stabilized upconversion nanoparticles as the core and ICG-loaded MCF7/ADR CMs as the shell, for combined chemo/phototherapy of MCF7/ADR tumor. The employment of phospholipid bilayers of CMs as natural pockets for extra drug loading while preserving the homologous targeting ability greatly enhanced drug concentration at tumor sites, endowing CMGNPs with excellent therapeutic efficacy. Our effort provides a versatile approach for facilitating drug delivery in diverse therapeutic systems.
Collapse
Affiliation(s)
- Siyu Chi
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Miaomiao Zuo
- College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, China
| | - Mengting Zhu
- College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, China
| | - Zijun Wang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Zhihong Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
- College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, China
| |
Collapse
|
5
|
Zhang O, Zhou W, Lu J, Wu T, Lew MD. Resolving the Three-Dimensional Rotational and Translational Dynamics of Single Molecules Using Radially and Azimuthally Polarized Fluorescence. Nano Lett 2022; 22:1024-1031. [PMID: 35073487 PMCID: PMC8893020 DOI: 10.1021/acs.nanolett.1c03948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report a radially and azimuthally polarized (raPol) microscope for high detection and estimation performance in single-molecule orientation-localization microscopy (SMOLM). With 5000 photons detected from Nile red (NR) transiently bound within supported lipid bilayers (SLBs), raPol SMOLM achieves 2.9 nm localization precision, 1.5° orientation precision, and 0.17 sr precision in estimating rotational wobble. Within DPPC SLBs, SMOLM imaging reveals the existence of randomly oriented binding pockets that prevent NR from freely exploring all orientations. Treating the SLBs with cholesterol-loaded methyl-β-cyclodextrin (MβCD-chol) causes NR's orientational diffusion to be dramatically reduced, but curiously NR's median lateral displacements drastically increase from 20.8 to 75.5 nm (200 ms time lag). These jump diffusion events overwhelmingly originate from cholesterol-rich nanodomains within the SLB. These detailed measurements of single-molecule rotational and translational dynamics are made possible by raPol's high measurement precision and are not detectable in standard SMLM.
Collapse
|
6
|
Palko-Łabuz A, Błaszczyk M, Środa-Pomianek K, Wesołowska O. Isobavachalcone as an Active Membrane Perturbing Agent and Inhibitor of ABCB1 Multidrug Transporter. Molecules 2021; 26:molecules26154637. [PMID: 34361789 PMCID: PMC8347294 DOI: 10.3390/molecules26154637] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/26/2021] [Accepted: 07/29/2021] [Indexed: 11/16/2022] Open
Abstract
Isobavachalcone (IBC) is an active substance from the medicinal plant Psoralea corylifolia. This prenylated chalcone was reported to possess antioxidative, anti-inflammatory, antibacterial, and anticancer activities. Multidrug resistance (MDR) associated with the over-expression of the transporters of vast substrate specificity such as ABCB1 (P-glycoprotein) belongs to the main causes of cancer chemotherapy failure. The cytotoxic, MDR reversing, and ABCB1-inhibiting potency of isobavachalcone was studied in two cellular models: human colorectal adenocarcinoma HT29 cell line and its resistant counterpart HT29/Dx in which doxorubicin resistance was induced by prolonged drug treatment, and the variant of MDCK cells transfected with the human gene encoding ABCB1. Because MDR modulators are frequently membrane-active substances, the interaction of isobavachalcone with model phosphatidylcholine bilayers was studied by means of differential scanning calorimetry. Molecular modeling was employed to characterize the process of membrane permeation by isobavachalcone. IBC interacted with ABCB1 transporter, being a substrate and/or competitive inhibitor of ABCB1. Moreover, IBC intercalated into model membranes, significantly affecting the parameters of their main phospholipid phase transition. It was concluded that isobavachalcone interfered both with the lipid phase of cellular membrane and with ABCB1 transporter, and for this reason, its activity in MDR cancer cells was presumptively beneficial.
Collapse
MESH Headings
- ATP Binding Cassette Transporter, Subfamily B/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B/genetics
- ATP Binding Cassette Transporter, Subfamily B/metabolism
- Animals
- Antibiotics, Antineoplastic/pharmacology
- Antineoplastic Agents, Phytogenic/chemistry
- Antineoplastic Agents, Phytogenic/isolation & purification
- Antineoplastic Agents, Phytogenic/pharmacology
- Binding, Competitive
- Cell Line, Tumor
- Chalcones/chemistry
- Chalcones/isolation & purification
- Chalcones/pharmacology
- Dogs
- Doxorubicin/pharmacology
- Drug Combinations
- Drug Resistance, Neoplasm/drug effects
- Drug Resistance, Neoplasm/genetics
- Gene Expression
- HT29 Cells
- Humans
- Inhibitory Concentration 50
- Lipid Bilayers/chemistry
- Lipid Bilayers/metabolism
- Madin Darby Canine Kidney Cells
- Membranes, Artificial
- Models, Molecular
- Phosphatidylcholines/chemistry
- Phosphatidylcholines/metabolism
- Plant Extracts/chemistry
- Plants, Medicinal
- Protein Binding
- Psoralea/chemistry
- Transgenes
- Verapamil/pharmacology
Collapse
|
7
|
Voskoboynikova N, Orekhov P, Bozdaganyan M, Kodde F, Rademacher M, Schowe M, Budke-Gieseking A, Brickwedde B, Psathaki OE, Mulkidjanian AY, Cosentino K, Shaitan KV, Steinhoff HJ. Lipid Dynamics in Diisobutylene-Maleic Acid (DIBMA) Lipid Particles in Presence of Sensory Rhodopsin II. Int J Mol Sci 2021; 22:2548. [PMID: 33806280 DOI: 10.3390/ijms22052548] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 01/01/2023] Open
Abstract
Amphiphilic diisobutylene/maleic acid (DIBMA) copolymers extract lipid-encased membrane proteins from lipid bilayers in a detergent-free manner, yielding nanosized, discoidal DIBMA lipid particles (DIBMALPs). Depending on the DIBMA/lipid ratio, the size of DIBMALPs can be broadly varied which makes them suitable for the incorporation of proteins of different sizes. Here, we examine the influence of the DIBMALP sizes and the presence of protein on the dynamics of encased lipids. As shown by a set of biophysical methods, the stability of DIBMALPs remains unaffected at different DIBMA/lipid ratios. Coarse-grained molecular dynamics simulations confirm the formation of viable DIBMALPs with an overall size of up to 35 nm. Electron paramagnetic resonance spectroscopy of nitroxides located at the 5th, 12th or 16th carbon atom positions in phosphatidylcholine-based spin labels reveals that the dynamics of enclosed lipids are not altered by the DIBMALP size. The presence of the membrane protein sensory rhodopsin II from Natronomonas pharaonis (NpSRII) results in a slight increase in the lipid dynamics compared to empty DIBMALPs. The light-induced photocycle shows full functionality of DIBMALPs-embedded NpSRII and a significant effect of the protein-to-lipid ratio during preparation on the NpSRII dynamics. This study indicates a possible expansion of the applicability of the DIBMALP technology on studies of membrane protein–protein interaction and oligomerization in a constraining environment.
Collapse
|
8
|
Lerner DA, Bégu S, Aubert-Pouëssel A, Polexe R, Devoisselle JM, Azaïs T, Tichit D. Synthesis and Properties of New Multilayer Chitosan@layered Double Hydroxide/Drug Loaded Phospholipid Bilayer Nanocomposite Bio-Hybrids. Materials (Basel) 2020; 13:ma13163565. [PMID: 32806728 PMCID: PMC7476003 DOI: 10.3390/ma13163565] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/06/2020] [Accepted: 08/10/2020] [Indexed: 12/17/2022]
Abstract
A novel bio-hybrid drug delivery system was obtained involving a Mg/Al-NO3 layered double hydroxide (LDH) intercalated either with ibuprofenate anions (IBU) or a phospholipid bilayer (BL) containing a neutral drug, i.e., 17β-estradiol, and then embedded in chitosan beads. The combination of these components in a hierarchical structure led to synergistic effects investigated through characterization of the intermediates and the final bio-composites by XRD, TG, SEM, and TEM. That allowed determining the presence and yield of IBU and of BL in the interlayer space of LDH, and of the encapsulated LDH in the beads, as well as the morphology of the latter. Peculiar attention has been paid to the intercalation process of the BL for which all available data substantiate the hypothesis of a first interaction at the defect of the LDH, as well as on the interaction mode of these components. 1H, 31P and 27Al MAS-NMR studies allowed establishing that the intercalated BL is not homogeneous and likely formed patches. Release kinetics were performed for sodium ibuprofenate as well as for the association of 17β-estradiol within the negatively charged BL, each encapsulated in the LDH/chitosan hybrid materials. Such new bio-hybrids offer an interesting outlook into the pharmaceutical domain with the ability to be used as sustained release systems for a wide variety of anionic and, importantly, neutral drugs.
Collapse
Affiliation(s)
- Dan A. Lerner
- ICGM, University of Montpellier, CNRS UMR 5253, ENSCM, 34296 Montpellier, France; (S.B.); (A.A.-P.); (R.P.); (J.-M.D.)
- Correspondence: (D.A.L.); (D.T.)
| | - Sylvie Bégu
- ICGM, University of Montpellier, CNRS UMR 5253, ENSCM, 34296 Montpellier, France; (S.B.); (A.A.-P.); (R.P.); (J.-M.D.)
| | - Anne Aubert-Pouëssel
- ICGM, University of Montpellier, CNRS UMR 5253, ENSCM, 34296 Montpellier, France; (S.B.); (A.A.-P.); (R.P.); (J.-M.D.)
| | - Ramona Polexe
- ICGM, University of Montpellier, CNRS UMR 5253, ENSCM, 34296 Montpellier, France; (S.B.); (A.A.-P.); (R.P.); (J.-M.D.)
| | - Jean-Marie Devoisselle
- ICGM, University of Montpellier, CNRS UMR 5253, ENSCM, 34296 Montpellier, France; (S.B.); (A.A.-P.); (R.P.); (J.-M.D.)
| | - Thierry Azaïs
- Laboratoire de Chimie de la Matière Condensèe de Paris (LCMCP), Collège de France, Sorbonne Université, CNRS, F-75005 Paris, France;
| | - Didier Tichit
- ICGM, University of Montpellier, CNRS UMR 5253, ENSCM, 34296 Montpellier, France; (S.B.); (A.A.-P.); (R.P.); (J.-M.D.)
- Correspondence: (D.A.L.); (D.T.)
| |
Collapse
|
9
|
Padmanabha Das KM, Shih WM, Wagner G, Nasr ML. Large Nanodiscs: A Potential Game Changer in Structural Biology of Membrane Protein Complexes and Virus Entry. Front Bioeng Biotechnol 2020; 8:539. [PMID: 32596222 PMCID: PMC7304444 DOI: 10.3389/fbioe.2020.00539] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 05/05/2020] [Indexed: 01/22/2023] Open
Abstract
Phospho-lipid bilayer nanodiscs have gathered much scientific interest as a stable and tunable membrane mimetic for the study of membrane proteins. Until recently the size of the nanodiscs that could be produced was limited to ~ 16 nm. Recent advances in nanodisc engineering such as covalently circularized nanodiscs (cND) and DNA corralled nanodiscs (DCND) have opened up the possibility of engineering nanodiscs of size up to 90 nm. This enables widening the application of nanodiscs from single membrane proteins to investigating large protein complexes and biological processes such as virus-membrane fusion and synaptic vesicle fusion. Another aspect of exploiting the large available surface area of these novel nanodiscs could be to engineer more realistic membrane mimetic systems with features such as membrane asymmetry and curvature. In this review, we discuss the recent technical developments in nanodisc technology leading to construction of large nanodiscs and examine some of the implicit applications.
Collapse
Affiliation(s)
- Krishna M Padmanabha Das
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
| | - William M Shih
- Wyss Institute for Biologically Inspired Engineering at Harvard, Boston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - Mahmoud L Nasr
- Renal Division and Engineering in Medicine Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| |
Collapse
|
10
|
Patra MC, Batool M, Haseeb M, Choi S. A Computational Probe into the Structure and Dynamics of the Full-Length Toll-Like Receptor 3 in a Phospholipid Bilayer. Int J Mol Sci 2020; 21:ijms21082857. [PMID: 32325904 PMCID: PMC7215789 DOI: 10.3390/ijms21082857] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 04/14/2020] [Accepted: 04/16/2020] [Indexed: 02/07/2023] Open
Abstract
Toll-like receptor 3 (TLR3) provides the host with antiviral defense by initiating an immune signaling cascade for the production of type I interferons. The X-ray structures of isolated TLR3 ectodomain (ECD) and transmembrane (TM) domains have been reported; however, the structure of a membrane-solvated, full-length receptor remains elusive. We investigated an all-residue TLR3 model embedded inside a phospholipid bilayer using molecular dynamics simulations. The TLR3-ECD exhibited a ~30°–35° tilt on the membrane due to the electrostatic interaction between the N-terminal subdomain and phospholipid headgroups. Although the movement of dsRNA did not affect the dimer integrity of TLR3, its sugar-phosphate backbone was slightly distorted with the orientation of the ECD. TM helices exhibited a noticeable tilt and curvature but maintained a consistent crossing angle, avoiding the hydrophobic mismatch with the bilayer. Residues from the αD helix and the CD and DE loops of the Toll/interleukin-1 receptor (TIR) domains were partially absorbed into the lower leaflet of the bilayer. We found that the previously unknown TLR3-TIR dimerization interface could be stabilized by the reciprocal contact between αC and αD helices of one subunit and the αC helix and the BB loop of the other. Overall, the present study can be helpful to understand the signaling-competent form of TLR3 in physiological environments.
Collapse
|
11
|
Staus DP, Wingler LM, Pichugin D, Prosser RS, Lefkowitz RJ. Detergent- and phospholipid-based reconstitution systems have differential effects on constitutive activity of G-protein-coupled receptors. J Biol Chem 2019; 294:13218-13223. [PMID: 31362983 DOI: 10.1074/jbc.ac119.009848] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 07/23/2019] [Indexed: 01/07/2023] Open
Abstract
A hallmark of G-protein-coupled receptors (GPCRs) is the conversion of external stimuli into specific cellular responses. In this tightly-regulated process, extracellular ligand binding by GPCRs promotes specific conformational changes within the seven transmembrane helices, leading to the coupling and activation of intracellular "transducer" proteins, such as heterotrimeric G proteins. Much of our understanding of the molecular mechanisms that govern GPCR activation is derived from experiments with purified receptors reconstituted in detergent micelles. To elucidate the influence of the phospholipid bilayer on GPCR activation, here we interrogated the functional, pharmacological, and biophysical properties of a GPCR, the β2-adrenergic receptor (β2AR), in high-density lipoprotein (HDL) particles. Compared with detergent-reconstituted β2AR, the β2AR in HDL particles had greatly enhanced levels of basal (constitutive) activity and displayed increased sensitivity to agonist activation, as assessed by activation of heterotrimeric G protein and allosteric coupling between the ligand-binding and transducer-binding pockets. Using 19F NMR spectroscopy, we directly linked these functional differences in detergent- and HDL-reconstituted β2AR to a change in the equilibrium between inactive and active receptor states. The contrast between the low levels of β2AR constitutive activity in cells and the high constitutive activity observed in an isolated phospholipid bilayer indicates that β2AR basal activity depends on the reconstitution system and further suggests that various cellular mechanisms suppress β2AR basal activity physiologically. Our findings provide critical additional insights into GPCR activation and reveal how dramatically reconstitution systems can impact membrane protein function.
Collapse
Affiliation(s)
- Dean P Staus
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710; Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710
| | - Laura M Wingler
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710; Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710
| | - Dmitry Pichugin
- Department of Chemistry, University of Toronto, UTM, Mississauga, Ontario L5L 1C6, Canada
| | - Robert Scott Prosser
- Department of Chemistry, University of Toronto, UTM, Mississauga, Ontario L5L 1C6, Canada.
| | - Robert J Lefkowitz
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710; Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710; Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
| |
Collapse
|
12
|
Willems N, Urtizberea A, Verre AF, Iliut M, Lelimousin M, Hirtz M, Vijayaraghavan A, Sansom MSP. Biomimetic Phospholipid Membrane Organization on Graphene and Graphene Oxide Surfaces: A Molecular Dynamics Simulation Study. ACS Nano 2017; 11:1613-1625. [PMID: 28165704 DOI: 10.1021/acsnano.6b07352] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Supported phospholipid membrane patches stabilized on graphene surfaces have shown potential in sensor device functionalization, including biosensors and biocatalysis. Lipid dip-pen nanolithography (L-DPN) is a method useful in generating supported membrane structures that maintain lipid functionality, such as exhibiting specific interactions with protein molecules. Here, we have integrated L-DPN, atomic force microscopy, and coarse-grained molecular dynamics simulation methods to characterize the molecular properties of supported lipid membranes (SLMs) on graphene and graphene oxide supports. We observed substantial differences in the topologies of the stabilized lipid structures depending on the nature of the surface (polar graphene oxide vs nonpolar graphene). Furthermore, the addition of water to SLM systems resulted in large-scale reorganization of the lipid structures, with measurable effects on lipid lateral mobility within the supported membranes. We also observed reduced lipid ordering within the supported structures relative to free-standing lipid bilayers, attributed to the strong hydrophobic interactions between the lipids and support. Together, our results provide insight into the molecular effects of graphene and graphene oxide surfaces on lipid bilayer membranes. This will be important in the design of these surfaces for applications such as biosensor devices.
Collapse
Affiliation(s)
- Nathalie Willems
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Ainhoa Urtizberea
- Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT) , 76344 Eggenstein-Leopoldshafen, Germany
| | - Andrea F Verre
- School of Materials and National Graphene Institute, University of Manchester , Manchester M13 9PL, United Kingdom
| | - Maria Iliut
- School of Materials and National Graphene Institute, University of Manchester , Manchester M13 9PL, United Kingdom
| | - Mickael Lelimousin
- CERMAV, CNRS and Université Grenoble Alpes , BP 53, Grenoble 38041 Cedex 9, France
| | - Michael Hirtz
- Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT) , 76344 Eggenstein-Leopoldshafen, Germany
| | - Aravind Vijayaraghavan
- School of Materials and National Graphene Institute, University of Manchester , Manchester M13 9PL, United Kingdom
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
| |
Collapse
|
13
|
Tan LTH, Chan KG, Pusparajah P, Lee WL, Chuah LH, Khan TM, Lee LH, Goh BH. Targeting Membrane Lipid a Potential Cancer Cure? Front Pharmacol 2017; 8:12. [PMID: 28167913 PMCID: PMC5253362 DOI: 10.3389/fphar.2017.00012] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 01/06/2017] [Indexed: 12/21/2022] Open
Abstract
Cancer mortality and morbidity is projected to increase significantly over the next few decades. Current chemotherapeutic strategies have significant limitations, and there is great interest in seeking novel therapies which are capable of specifically targeting cancer cells. Given that fundamental differences exist between the cellular membranes of healthy cells and tumor cells, novel therapies based on targeting membrane lipids in cancer cells is a promising approach that deserves attention in the field of anticancer drug development. Phosphatidylethanolamine (PE), a lipid membrane component which exists only in the inner leaflet of cell membrane under normal circumstances, has increased surface representation on the outer membrane of tumor cells with disrupted membrane asymmetry. PE thus represents a potential chemotherapeutic target as the higher exposure of PE on the membrane surface of cancer cells. This feature as well as a high degree of expression of PE on endothelial cells in tumor vasculature, makes PE an attractive molecular target for future cancer interventions. There have already been several small molecules and membrane-active peptides identified which bind specifically to the PE molecules on the cancer cell membrane, subsequently inducing membrane disruption leading to cell lysis. This approach opens up a new front in the battle against cancer, and is of particular interest as it may be a strategy that may be prove effective against tumors that respond poorly to current chemotherapeutic agents. We aim to highlight the evidence suggesting that PE is a strong candidate to be explored as a potential molecular target for membrane targeted novel anticancer therapy.
Collapse
Affiliation(s)
- Loh Teng-Hern Tan
- Novel Bacteria and Drug Discovery Research Group, School of Pharmacy, Monash University Malaysia Bandar Sunway, Malaysia
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia
| | - Priyia Pusparajah
- Biomedical Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia Bandar Sunway, Malaysia
| | - Wai-Leng Lee
- School of Science, Monash University Malaysia Selangor, Malaysia
| | - Lay-Hong Chuah
- Novel Bacteria and Drug Discovery Research Group, School of Pharmacy, Monash University Malaysia Bandar Sunway, Malaysia
| | - Tahir Mehmood Khan
- Novel Bacteria and Drug Discovery Research Group, School of Pharmacy, Monash University MalaysiaBandar Sunway, Malaysia; Department of Pharmacy, Abasyn University PeshawarPeshawar, Pakistan
| | - Learn-Han Lee
- Novel Bacteria and Drug Discovery Research Group, School of Pharmacy, Monash University MalaysiaBandar Sunway, Malaysia; Center of Health Outcomes Research and Therapeutic Safety, School of Pharmaceutical Sciences, University of PhayaoPhayao, Thailand
| | - Bey-Hing Goh
- Novel Bacteria and Drug Discovery Research Group, School of Pharmacy, Monash University MalaysiaBandar Sunway, Malaysia; Center of Health Outcomes Research and Therapeutic Safety, School of Pharmaceutical Sciences, University of PhayaoPhayao, Thailand
| |
Collapse
|
14
|
Moulay G, Leborgne C, Mason AJ, Aisenbrey C, Kichler A, Bechinger B. Histidine-rich designer peptides of the LAH4 family promote cell delivery of a multitude of cargo. J Pept Sci 2017; 23:320-328. [PMID: 28067008 DOI: 10.1002/psc.2955] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 11/09/2022]
Abstract
The histidine-rich designer peptides of the LAH4 family exhibit potent antimicrobial, transfection, transduction and cell-penetrating properties. They form non-covalent complexes with their cargo, which often carry a negative overall charge at pH 7.4 and include a large range of molecules and structures such as oligonucleotides, including siRNA and DNA, peptides, proteins, nanodots and adeno-associated viruses. These complexes are thought to enter the cells through an endosomal pathway where the acidification of the organelle is essential for efficient endosomal escape. Biophysical measurements indicate that, upon acidification, almost half the peptides are released from DNA cargo, leading to the suggestion of a self-promoted uptake mechanism where the liberated peptides lyse the endosomal membranes. LAH4 derivatives also help in cellular transduction using lentiviruses. Here, we compare the DNA transfection activities of LAH4 derivatives, which vary in overall charge and/or the composition in the hydrophobic core region. In addition, LAH4 is shown to mediate the transport of functional β-galactosidase, a large tetrameric protein of about 0.5 MDa, into the cell interior. Interestingly, the LAH1 peptide efficiently imports this protein, while it is inefficient during DNA transfection assays. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Gilles Moulay
- Genethon, 1bis rue de l'Internationale, 91002, Evry, France
| | | | - A James Mason
- Université de Strasbourg, CNRS, UMR7177, Institut de Chimie, 4, Rue Blaise Pascal, 67070, Strasbourg, France.,Institute of Pharmaceutical Science, King's College London, 150 Stamford Street, London, UK
| | - Christopher Aisenbrey
- Université de Strasbourg, CNRS, UMR7177, Institut de Chimie, 4, Rue Blaise Pascal, 67070, Strasbourg, France
| | - Antoine Kichler
- Genethon, 1bis rue de l'Internationale, 91002, Evry, France.,Faculté de Pharmacie, Laboratoire de Conception et Application de Molécules Bioactives UMR7199 CNRS - Université de Strasbourg, Labex Medalis, 67401, Illkirch, France
| | - Burkhard Bechinger
- Université de Strasbourg, CNRS, UMR7177, Institut de Chimie, 4, Rue Blaise Pascal, 67070, Strasbourg, France
| |
Collapse
|
15
|
Huang Y, Cole SP, Cai T, Cai YU. Applications of nanoparticle drug delivery systems for the reversal of multidrug resistance in cancer. Oncol Lett 2016; 12:11-5. [PMID: 27347092 DOI: 10.3892/ol.2016.4596] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Accepted: 04/29/2016] [Indexed: 11/05/2022] Open
Abstract
Multidrug resistance (MDR) to chemotherapy presents a major obstacle in the treatment of cancer patients, which directly affects the clinical success rate of cancer therapy. Current research aims to improve the efficiency of chemotherapy, whilst reducing toxicity to prolong the lives of cancer patients. As with good biocompatibility, high stability and drug release targeting properties, nanodrug delivery systems alter the mechanism by which drugs function to reverse MDR, via passive or active targeting, increasing drug accumulation in the tumor tissue or reducing drug elimination. Given the potential role of nanodrug delivery systems used in multidrug resistance, the present study summarizes the current knowledge on the properties of liposomes, lipid nanoparticles, polymeric micelles and mesoporous silica nanoparticles, together with their underlying mechanisms. The current review aims to provide a reliable basis and useful information for the development of new treatment strategies of multidrug resistance reversal using nanodrug delivery systems.
Collapse
|
16
|
Collu F, Spiga E, Lorenz CD, Fraternali F. Assembly of Influenza Hemagglutinin Fusion Peptides in a Phospholipid Bilayer by Coarse-grained Computer Simulations. Front Mol Biosci 2015; 2:66. [PMID: 26636093 PMCID: PMC4649048 DOI: 10.3389/fmolb.2015.00066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 11/03/2015] [Indexed: 11/22/2022] Open
Abstract
Membrane fusion is critical to eukaryotic cellular function and crucial to the entry of enveloped viruses such as influenza and human immunodeficiency virus. Influenza viral entry in the host cell is mediated by a 20–23 amino acid long sequence, called the fusion peptide (FP). Recently, possible structures for the fusion peptide (ranging from an inverted V shaped α-helical structure to an α-helical hairpin, or to a complete α-helix) and their implication in the membrane fusion initiation have been proposed. Despite the large number of studies devoted to the structure of the FP, the mechanism of action of this peptide remains unclear with several mechanisms having been suggested, including the induction of local disorder, promoting membrane curvature, and/or altering local membrane composition. In recent years, several research groups have employed atomistic and/or coarse-grained molecular dynamics (MD) simulations to investigate the matter. In all previous works, the behavior of a single FP monomer was studied, while in this manuscript, we use a simplified model of a tripeptide (TP) monomer of FP (TFP) instead of a single FP monomer because each Influenza Hemagglutinin contains three FP molecules in the biological system. In this manuscript we report findings targeted at understanding the fusogenic properties and the collective behavior of these trimers of FP peptides on a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine model membrane. Here we show how the TFP monomers self-assemble into differently sized oligomers in the presence of the membrane. We measure the perturbation to the structure of the phospholipid membrane caused by the presence of these TFP oligomers. Our work (i) shows how self-assembly of TFP in the presence of the membrane induces non negligible deformation to the membrane and (ii) could be a useful starting point to stimulate discussion and further work targeted to fusion pore formation.
Collapse
Affiliation(s)
- Francesca Collu
- Randall Division of Cell and Molecular Biophysics, Bioinformatics Computational Biology, King's College London London, UK
| | - Enrico Spiga
- Mill Hill Laboratory, Mathematical Biology, The Francis Crick Institute London, UK
| | - Christian D Lorenz
- Theory and Simulation of Condensed Matter Group, Department of Physics, King's College London London, UK
| | - Franca Fraternali
- Randall Division of Cell and Molecular Biophysics, Bioinformatics Computational Biology, King's College London London, UK
| |
Collapse
|
17
|
Taheri S, Cavallaro A, Christo SN, Majewski P, Barton M, Hayball JD, Vasilev K. Antibacterial Plasma Polymer Films Conjugated with Phospholipid Encapsulated Silver Nanoparticles. ACS Biomater Sci Eng 2015; 1:1278-1286. [PMID: 33429675 DOI: 10.1021/acsbiomaterials.5b00338] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Medical device associated infections are a persistent medical problem which has not found a comprehensive solution yet. Over the last decades, there have been intense research efforts toward developing antibacterial coatings that could potentially improve medical outcomes. Silver nanoparticles have attracted a great deal of attention as a potent alternative to conventional antibiotics. Herein, we present a biologically inspired approach to synthesize phospholipid encapsulated silver nanoparticles and their surface immobilization to a functional plasma polymer interlayer to generate antibacterial coatings. The antibacterial efficacy of the coatings was evaluated against three medically relevant pathogens including the Gram-positive Staphylococcus aureus and Staphylococcus epidermidis, and the Gram-negative Pseudomonas aeruginosa. The innate immune response to the coatings was assessed in vitro using primary bone marrow derived macrophages (BMDM). Any potential cytotoxicity was studied with primary human dermal fibroblasts (HDFs). Overall, the coatings had excellent inhibition of bacterial growth. We also observed reduced expression of pro-inflammatory cytokines from BMDM which suggests a reduced inflammatory response. The combined properties of coatings developed in this study may make them a good candidate for application on medical devices such as catheters and wound dressings.
Collapse
Affiliation(s)
- Shima Taheri
- School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Alex Cavallaro
- School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Susan N Christo
- Sansom Institute, University of South Australia, Adelaide, SA 5000, Australia
| | - Peter Majewski
- School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Mary Barton
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - John D Hayball
- Sansom Institute, University of South Australia, Adelaide, SA 5000, Australia.,School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Krasimir Vasilev
- School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia
| |
Collapse
|
18
|
Tian Y, Lu GJ, Marassi FM, Opella SJ. Structure of the membrane protein MerF, a bacterial mercury transporter, improved by the inclusion of chemical shift anisotropy constraints. J Biomol NMR 2014; 60:67-71. [PMID: 25103921 PMCID: PMC4154067 DOI: 10.1007/s10858-014-9852-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/04/2014] [Indexed: 05/28/2023]
Abstract
MerF is a mercury transport membrane protein from the bacterial mercury detoxification system. By performing a solid-state INEPT experiment and measuring chemical shift anisotropy frequencies in aligned samples, we are able to improve on the accuracy and precision of the initial structure that we presented. MerF has four N-terminal and eleven C-terminal residues that are mobile and unstructured in phospholipid bilayers. The structure presented here has average pairwise RMSDs of 1.78 Å for heavy atoms and 0.92 Å for backbone atoms.
Collapse
Affiliation(s)
- Ye Tian
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0307, USA
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - George J. Lu
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0307, USA
| | - Francesca M. Marassi
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Stanley J. Opella
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0307, USA
| |
Collapse
|
19
|
Zheng H, Jiménez-Flores R, Gragson D, Everett DW. Phospholipid Architecture of the Bovine Milk Fat Globule Membrane Using Giant Unilamellar Vesicles as a Model. J Agric Food Chem 2014; 62:3236-3243. [PMID: 24641452 DOI: 10.1021/jf500093p] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Giant unilamellar vesicles (GUVs) were constructed using an electroformation technique to mimic the morphology of the native milk fat globule membrane (MFGM) for the purpose of structural investigation. Bovine milk derived phospholipids were selected to manufacture GUVs which were characterized by confocal laser scanning microscopy after fluorescent staining. Circular nonfluorescent dark regions were observed in a 3/7 (mol/mol) surface mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3 phosphoethanolamine. Linear shaped dark lipid domains were found in GUVs containing sphingomyelin (SM) in the absence of cholesterol. The dark regions were interpreted as a gel phase formed by a high gel-liquid phase transition temperature (Tm) of DPPC and SM. This study provides a strategy for investigating the lipid structural organization within the native MFGM using a model lipid bilayer system and reveals that a SM and cholesterol association network is not the only requirement for nonfluorescent lipid domain formation and that PE is preferably located in the inner leaflet of the phospholipid bilayer.
Collapse
Affiliation(s)
- Haotian Zheng
- Riddet Institute , Palmerston North, 4442 Manawatu, New Zealand
- Department of Food Science, University of Otago , Dunedin, 9054 Otago, New Zealand
- Dairy Products Technology Center, California Polytechnic State University , San Luis Obispo, 93407 California, United States
| | - Rafael Jiménez-Flores
- Dairy Products Technology Center, California Polytechnic State University , San Luis Obispo, 93407 California, United States
| | - Derek Gragson
- Department of Chemistry and Biochemistry, California Polytechnic State University , San Luis Obispo, 93407 California, United States
| | - David W Everett
- Riddet Institute , Palmerston North, 4442 Manawatu, New Zealand
- Department of Food Science, University of Otago , Dunedin, 9054 Otago, New Zealand
| |
Collapse
|
20
|
Abstract
Biological membranes are complex assemblies of many different molecules of which analysis demands a variety of experimental and computational approaches. In this article, we explain challenges and advantages of atomistic Monte Carlo (MC) simulation of lipid membranes. We provide an introduction into the various move sets that are implemented in current MC methods for efficient conformational sampling of lipids and other molecules. In the second part, we demonstrate for a concrete example, how an atomistic local-move set can be implemented for MC simulations of phospholipid monomers and bilayer patches. We use our recently devised chain breakage/closure (CBC) local move set in the bond-/torsion angle space with the constant-bond-length approximation (CBLA) for the phospholipid dipalmitoylphosphatidylcholine (DPPC). We demonstrate rapid conformational equilibration for a single DPPC molecule, as assessed by calculation of molecular energies and entropies. We also show transition from a crystalline-like to a fluid DPPC bilayer by the CBC local-move MC method, as indicated by the electron density profile, head group orientation, area per lipid, and whole-lipid displacements. We discuss the potential of local-move MC methods in combination with molecular dynamics simulations, for example, for studying multi-component lipid membranes containing cholesterol.
Collapse
Affiliation(s)
- Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M DK-5230, Denmark.
| | - Heinz Sklenar
- Theoretical Biophysics Group, Max Delbrück Center for Molecular Medicine, Robert-Rössle-Str. 10, Berlin D-13125, Germany.
| |
Collapse
|
21
|
Park SH, Casagrande F, Chu M, Maier K, Kiefer H, Opella SJ. Optimization of purification and refolding of the human chemokine receptor CXCR1 improves the stability of proteoliposomes for structure determination. Biochim Biophys Acta 2012; 1818:584-91. [PMID: 22024025 PMCID: PMC3777732 DOI: 10.1016/j.bbamem.2011.10.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 10/03/2011] [Accepted: 10/06/2011] [Indexed: 12/11/2022]
Abstract
The human chemokine receptor CXCR1 is a G-protein coupled receptor that has been successfully expressed in E. coli as inclusion bodies, and purified and refolded in multi-milligram quantities required for structural studies. Expression in E. coli enables selective and uniform isotopic labeling with (13)C and (15)N for NMR studies. Long-term chemical and conformational stability and oligomeric homogeneity of CXCR1 in phospholipid bilayers are crucial for structural studies under physiological conditions. Here we describe substantial refinements in our previously described purification and reconstitution procedures for CXCR1 in phospholipid bilayers. These refinements have led to the preparation of highly purified, completely monomeric, proteoliposome samples that are stable for months at 35°C while subject to the high power radiofrequency irradiations of solid-state NMR experiments. The principal changes from the previously described methods include: 1) ensure that CXCR1 is pure and homogeneously monomeric within the limits of detection (>98%); 2) monitor and control the pH at all times especially following the addition of TCEP, which serves as a reducing agent but also changes the pH; 3) slowly refold CXCR1 with the complete removal of all traces of SDS using a KCl precipitation/dialysis method; and 4) ensure that the molar ratio between the CXCR1 and the phospholipids does not change during refolding and detergent removal. NMR samples prepared with these protocols yield reproducible results over a period of many months at 35°C. This purification and refolding protocol is likely to be applicable with minimal changes to other GPCRs as well as other membrane proteins.
Collapse
Affiliation(s)
- Sang Ho Park
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307, USA
| | - Fabio Casagrande
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307, USA
| | - Mignon Chu
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307, USA
| | - Klaus Maier
- Membrane Receptor Technologies, San Diego, CA 92121-3832, USA
| | | | - Stanley J. Opella
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307, USA
| |
Collapse
|
22
|
Kelly CV, Liroff MG, Triplett LD, Leroueil PR, Mullen DG, Wallace JM, Meshinchi S, Baker JR, Orr BG, Banaszak Holl MM. Stoichiometry and Structure of Poly(amidoamine) Dendrimer-Lipid Complexes. ACS Nano 2009; 3:1886-1896. [PMID: 19534489 PMCID: PMC2888816 DOI: 10.1021/nn900173e] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The energetics, stoichiometry, and structure of poly(amidoamine) (PAMAM) dendrimer-phospholipid interactions were measured with isothermal titration calorimetry (ITC), transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and molecular dynamics (MD) simulations. Dendrimers of sixth-generation and smaller interacted with the lipids at an average stoichiometry and enthalpy proportional to the number of primary amines per dendrimers (4.5 ± 0.1 lipids/primary amine and 6.3 ± 0.3 kJ/mol of primary amines, respectively). Larger dendrimers, however, demonstrated a decreased number of bound lipids and heat release per primary amine, presumably due to the steric restriction of dendrimer deformation on the lipid bilayer. For example, eighth-generation PAMAM dendrimers bound to 44% fewer lipids per primary amine and released 63% less heat per primary amine as compared to the smaller dendrimers. These differences in binding stoichiometry support generation-dependent models for dendrimer-lipid complexation, which are consistent with previously observed generation-dependent differences in dendrimer-induced membrane disruption. Dendrimers of seventh-generation and larger bound to lipids with an average stoichiometry consistent with each dendrimer having been wrapped by a bilayer of lipids, whereas smaller dendrimers did not.
Collapse
|
23
|
Abstract
Using fluorescence microscopy, we show that previously isolated membrane-binding RNAs coat artificial phospholipid membranes relatively uniformly, except for a frequent tendency to concentrate at bends, membrane junctions, and other unusual sites. Membrane RNAs can also be visualized as single molecules or isolated complexes by atomic force microscopy (AFM) of free RNAs on mica. Finally, RNAs can be seen within membranes by AFM of RNA-liposomes immobilized on hydrophobic mica surfaces. Monomer RNAs appear globular, as expected for small RNAs. When mixed under conditions in which RNAs bind bilayers, RNA 9 and RNA 10 combine to yield about 80% of RNAs as mainly linear oligomers of approximately 2-8 molecules. Once inserted in membranes, the RNAs oligomerize further, yielding larger, irregular ropelike structures that prefer the edges of altered lipid patches. These properties can be interpreted in terms of RNA-RNA loop interactions, and the RNA effects on membranes can be explained in terms of an RNA preference for irregular lipid conformations. The RNA-bilayer system poses new opportunities for combining the properties of membranes and RNA in contemporary cells, and also in the ribocytes of an RNA world.
Collapse
Affiliation(s)
- Tadeusz Janas
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309-0347, USA
| | | |
Collapse
|
24
|
LeGrue SJ. Carrier and adjuvant properties of liposome-borne tumor-specific antigens. Cancer Immunol Immunother 1984; 17:135-41. [PMID: 6565518 PMCID: PMC11039198 DOI: 10.1007/bf00200050] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/1983] [Accepted: 04/06/1984] [Indexed: 10/26/2022]
Abstract
The purpose of this study was to examine (1) the association of tumor extract proteins with phospholipid vesicles of varying physiochemical properties, and (2) the adjuvant and carrier properties of liposome-borne tumor antigens in the in vivo induction of an antitumor immune response. Cell surface antigens of the 3-methylcholanthrene-induced fibrosarcoma of C3H/HeJ mice, MCA-F, were extracted using 2.5% 1-butanol. Crude and electrofocused antigen preparations capable of eliciting a protective antitumor immune response were used to prepare liposome vaccines. The incorporation of extract proteins into liposomes formed by butanol dialysis (BVD) was three- to five-fold greater than the encapsulation of protein into the aqueous compartment of multilamellar vesicles (MLV). The electrochemical properties of the BDV had a significant effect on the induction of an antitumor response: Antigens borne on negatively charged, but not uncharged, liposomes were effective in protecting hosts against supralethal tumor challenge, and displayed a specific activity 20- to 50-fold greater than soluble antigen. Antigens carried by MLV were not effective in generating an immunoprotective response. The lipophilic characteristics of butanol-extracted antigens allowed (1) the passive adsorption of immunoprotective tumor antigen onto the surface of preformed vesicles, and (2) adsorption of MCA-F antigen onto the surface of an antigenically distinct tumor MCA-D. In the latter experiment, adsorption of MCA-F-specific antigen onto MCA-D cells resulted in a change in the membrane antigen phenotype as measured by indirect immunofluorescence. Although butanol released a lipophilic moiety from cells which spontaneously reassociated with phospholipid bilayers, no evidence for a lipoidal antigen was obtained when tumor-derived lipids were used as immunogens. This study demonstrates that butanol-extracted tumor antigen is lipophilic without being a lipid, and that negatively charged liposomes can be effective as carriers and adjuvants for tumor antigens in the induction of an antitumor immune response.
Collapse
|
25
|
Mashimo T, Ueda I, Shieh DD, Kamaya H, Eyring H. Hydrophilic region of lecithin membranes studied by bromothymol blue and effects of an inhalation anesthetic, enflurane. Proc Natl Acad Sci U S A 1979; 76:5114-8. [PMID: 41238 PMCID: PMC413090 DOI: 10.1073/pnas.76.10.5114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A pH-indicator dye, bromothymol blue, was used to probe the hydrophilic surface of dimyristoyl-, dipalmitoyl-, and distearoylphosphatidylcholine bilayer vesicles. The apparent pK of the surface-adsorbed dye was larger than the bulk pK value. The contribution of the choline positive charge on the dissociation constant of the dye adsorbed on the vesicle surface was estimated by screening the charge interaction with 2 M KCl. The effective surface potentials interacting with the dye were thus estimated to be 33.2, 45.6, and 46.8 mV, respectively, for the dimyristoyl-, dipalmitoyl-, and distearoylphosphatidylcholine vesicles. From the differences between the obtained effective potentials and the calculated surface potentials of the charge-determining plane of the choline head, the distances between the prototropic part of the dye and the choline charge-determining plane were estimated to be 10.5, 8.0, and 7.8 A, respectively. These values were obtained at 25 degrees C; the dimyristoylphosphatidylcholine membrane was in the liquid-crystalline phase and the other two were in the solid gel phase. Addition of an inhalation anesthetic, enflurane, decreased the distance in the dimyristoylphosphatidylcholine vesicles and increased the distance in the dipalmitoyl- and distearoylphosphatidylcholine vesicles. The increase of precessional motion of choline head by the inhalation anesthetic is apparently responsible for the changes.
Collapse
|