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Pflüger T, Gschell M, Zhang L, Shnitsar V, Zabadné AJ, Zierep P, Günther S, Einsle O, Andrade SLA. How sensor Amt-like proteins integrate ammonium signals. SCIENCE ADVANCES 2024; 10:eadm9441. [PMID: 38838143 DOI: 10.1126/sciadv.adm9441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 04/30/2024] [Indexed: 06/07/2024]
Abstract
Unlike aquaporins or potassium channels, ammonium transporters (Amts) uniquely discriminate ammonium from potassium and water. This feature has certainly contributed to their repurposing as ammonium receptors during evolution. Here, we describe the ammonium receptor Sd-Amt1, where an Amt module connects to a cytoplasmic diguanylate cyclase transducer module via an HAMP domain. Structures of the protein with and without bound ammonium were determined to 1.7- and 1.9-Ångstrom resolution, depicting the ON and OFF states of the receptor and confirming the presence of a binding site for two ammonium cations that is pivotal for signal perception and receptor activation. The transducer domain was disordered in the crystals, and an AlphaFold2 prediction suggests that the helices linking both domains are flexible. While the sensor domain retains the trimeric fold formed by all Amt family members, the HAMP domains interact as pairs and serve to dimerize the transducer domain upon activation.
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Affiliation(s)
- Tobias Pflüger
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Mathias Gschell
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Lin Zhang
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Volodymyr Shnitsar
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Annas J Zabadné
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Paul Zierep
- Faculty of Chemistry and Pharmacy, Institute for Pharmaceutical Sciences, University Freiburg, Hermann-Herder-Str. 9, 79104 Freiburg, Germany
| | - Stefan Günther
- Faculty of Chemistry and Pharmacy, Institute for Pharmaceutical Sciences, University Freiburg, Hermann-Herder-Str. 9, 79104 Freiburg, Germany
| | - Oliver Einsle
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University Freiburg, Schänzlerstr. 1, 79104 Freiburg, Germany
| | - Susana L A Andrade
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University Freiburg, Schänzlerstr. 1, 79104 Freiburg, Germany
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2
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Bazzone A, Barthmes M, George C, Brinkwirth N, Zerlotti R, Prinz V, Cole K, Friis S, Dickson A, Rice S, Lim J, Fern Toh M, Mohammadi M, Pau D, Stone DJ, Renger JJ, Fertig N. A Comparative Study on the Lysosomal Cation Channel TMEM175 Using Automated Whole-Cell Patch-Clamp, Lysosomal Patch-Clamp, and Solid Supported Membrane-Based Electrophysiology: Functional Characterization and High-Throughput Screening Assay Development. Int J Mol Sci 2023; 24:12788. [PMID: 37628970 PMCID: PMC10454728 DOI: 10.3390/ijms241612788] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/09/2023] [Accepted: 08/12/2023] [Indexed: 08/27/2023] Open
Abstract
The lysosomal cation channel TMEM175 is a Parkinson's disease-related protein and a promising drug target. Unlike whole-cell automated patch-clamp (APC), lysosomal patch-clamp (LPC) facilitates physiological conditions, but is not yet suitable for high-throughput screening (HTS) applications. Here, we apply solid supported membrane-based electrophysiology (SSME), which enables both direct access to lysosomes and high-throughput electrophysiological recordings. In SSME, ion translocation mediated by TMEM175 is stimulated using a concentration gradient at a resting potential of 0 mV. The concentration-dependent K+ response exhibited an I/c curve with two distinct slopes, indicating the existence of two conducting states. We measured H+ fluxes with a permeability ratio of PH/PK = 48,500, which matches literature findings from patch-clamp studies, validating the SSME approach. Additionally, TMEM175 displayed a high pH dependence. Decreasing cytosolic pH inhibited both K+ and H+ conductivity of TMEM175. Conversely, lysosomal pH and pH gradients did not have major effects on TMEM175. Finally, we developed HTS assays for drug screening and evaluated tool compounds (4-AP, Zn as inhibitors; DCPIB, arachidonic acid, SC-79 as enhancers) using SSME and APC. Additionally, we recorded EC50 data for eight blinded TMEM175 enhancers and compared the results across all three assay technologies, including LPC, discussing their advantages and disadvantages.
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Affiliation(s)
- Andre Bazzone
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Maria Barthmes
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Cecilia George
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Nina Brinkwirth
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Rocco Zerlotti
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
- RIGeL-Regensburg International Graduate School of Life Sciences, University of Regensburg, 93053 Regensburg, Germany
| | - Valentin Prinz
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Kim Cole
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Søren Friis
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Alexander Dickson
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - Simon Rice
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - Jongwon Lim
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - May Fern Toh
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | | | - Davide Pau
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - David J. Stone
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - John J. Renger
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - Niels Fertig
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
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3
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He X, Ewing AG. Hofmeister Series: From Aqueous Solution of Biomolecules to Single Cells and Nanovesicles. Chembiochem 2023; 24:e202200694. [PMID: 37043703 DOI: 10.1002/cbic.202200694] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/30/2023] [Indexed: 04/14/2023]
Abstract
Hofmeister effects play a critical role in numerous physicochemical and biological phenomena, including the solubility and/or accumulation of proteins, the activities of enzymes, ion transport in biochannels, the structure of lipid bilayers, and the dynamics of vesicle opening and exocytosis. This minireview focuses on how ionic specificity affects the physicochemical properties of biomolecules to regulate cellular exocytosis, vesicular content, and nanovesicle opening. We summarize recent progress in further understanding Hofmeister effects on biomacromolecules and their applications in biological systems. These important steps have increased our understanding of the Hofmeister effects on cellular exocytosis, vesicular content, and nanovesicle opening. Increasing evidence is firmly establishing that the ions along the Hofmeister series play an important role in living organisms that has often been ignored.
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Affiliation(s)
- Xiulan He
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, 41296, Gothenburg, Sweden
| | - Andrew G Ewing
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, 41296, Gothenburg, Sweden
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4
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Dong Y, Fu L, Song J, Zhang S, Li X, Fang W, Cui Q, Gao L. Thermodynamic Driving Forces for Divalent Cations Binding to Zwitterionic Phospholipid Membranes. J Phys Chem Lett 2022; 13:11237-11244. [PMID: 36448843 DOI: 10.1021/acs.jpclett.2c03019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We calculated the free energies for calcium, magnesium, and zinc ions binding to a zwitterionic phospholipid bilayer by using molecular dynamics simulations and the enhanced umbrella sampling technique. By decomposing the free energy into entropic and enthalpic contributions, we found that Ca2+ has the highest binding affinity and that the overall process is endothermic combined with a secondary exothermic process at higher ion concentrations. The relatively low dehydration free energy of Ca2+ allows it to release coordinated water upon binding to the membrane. The dehydrated Ca2+ further coordinates with lipids, resulting in a weaker influence on the water orientation and increased entropy. However, when sufficient Ca2+ ions are adsorbed, the concentrated cation layer induces a positive electrostatic field, which enhances the energy barrier for further ion binding and orients the adjacent water, resulting in decreased entropy. In contrast, binding of Mg2+ and Zn2+ is exothermic and less favored because they remain fully hydrated when interacting with lipids.
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Affiliation(s)
- Yi Dong
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Lei Fu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts02215, United States
| | - Junjie Song
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Shan Zhang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Xiangyuan Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Weihai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Qiang Cui
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts02215, United States
| | - Lianghui Gao
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
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5
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Bazzone A, Körner A, Meincke M, Bhatt M, Dondapati S, Barthmes M, Kubick S, Fertig N. SSM-based electrophysiology, a label-free real-time method reveals sugar binding & transport events in SGLT1. Biosens Bioelectron 2022; 197:113763. [PMID: 34768066 DOI: 10.1016/j.bios.2021.113763] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/26/2021] [Accepted: 10/30/2021] [Indexed: 01/26/2023]
Abstract
Here, we present a solid-supported membrane (SSM)-based electrophysiological approach to study sugar binding and Na+/glucose cotransport by SGLT1 in membrane vesicles. SSM-based electrophysiology delivers a cumulative real-time current readout from numerous SGLT1 proteins simultaneously using a gold-coated sensor chip. In contrast to conventional techniques, which mainly operate with voltage steps, currents are triggered by sugar or sodium addition. Sugar concentration jumps in the presence of sodium lead to transport currents between 5 and 10 nA. Remarkably, in the absence of sodium (i.e. no transport), we observed fast pre-steady-state (PSS) currents with time constants between 3 and 10 ms. These PSS currents mainly originate from sugar binding. Sodium binding does not induce PSS currents. Due to high time resolution, PSS currents were distinguished from transport and eventually correlated with conformational transitions within the sugar translocation pathway. In addition, we analyzed the impact of driving forces on transport and binding currents, showing that membrane voltage and sodium concentration gradients lead to an increased transport rate without affecting sugar binding kinetics. We also compared Na+/sugar efflux with physiologically relevant influx and found similar transport rates, but lower affinity in efflux mode. SSM-based electrophysiology is a powerful technique, which overcomes bottlenecks for transport measurements observed in other techniques such as the requirement of labels or the lack of real-time data. Rapid solution exchange enables the observation of substrate-induced electrogenic events like conformational transitions, opening novel perspectives for in-depth functional studies of SGLT1 and other transporters.
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Affiliation(s)
- Andre Bazzone
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339, Munich, Germany.
| | - Alexander Körner
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476, Potsdam, Germany; Institute of Biotechnology, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355, Berlin, Germany
| | - Melanie Meincke
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339, Munich, Germany
| | - Manan Bhatt
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339, Munich, Germany
| | - Srujan Dondapati
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476, Potsdam, Germany
| | - Maria Barthmes
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339, Munich, Germany
| | - Stefan Kubick
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476, Potsdam, Germany; Freie Universität Berlin, Institute of Chemistry and Biochemistry - Biochemistry, 14195, Berlin, Germany; Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus - Senftenberg, the Brandenburg Medical School Theodor Fontane and the University of Potsdam, Germany
| | - Niels Fertig
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339, Munich, Germany
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6
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Abstract
The ubiquity of aqueous solutions in contact with charged surfaces and the realization that the molecular-level details of water-surface interactions often determine interfacial functions and properties relevant in many natural processes have led to intensive research. Even so, many open questions remain regarding the molecular picture of the interfacial organization and preferential alignment of water molecules, as well as the structure of water molecules and ion distributions at different charged interfaces. While water, solutes and charge are present in each of these systems, the substrate can range from living tissues to metals. This diversity in substrates has led to different communities considering each of these types of aqueous interface. In this Review, by considering water in contact with metals, oxides and biomembranes, we show the essential similarity of these disparate systems. While in each case the classical mean-field theories can explain many macroscopic and mesoscopic observations, it soon becomes apparent that such theories fail to explain phenomena for which molecular properties are relevant, such as interfacial chemical conversion. We highlight the current knowledge and limitations in our understanding and end with a view towards future opportunities in the field.
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7
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He X, Ewing AG. Counteranions in the Stimulation Solution Alter the Dynamics of Exocytosis Consistent with the Hofmeister Series. J Am Chem Soc 2020; 142:12591-12595. [PMID: 32598145 PMCID: PMC7386575 DOI: 10.1021/jacs.0c05319] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
![]()
We
show that the Hofmeister series of ions can be used to explain
the cellular changes in exocytosis observed by single-cell amperometry
for different counteranions. The formation, expansion, and closing
of the membrane fusion pore during exocytosis was found to be strongly
dependent on the counteranion species in solution. With stimulation
of chaotropic anions (e.g., ClO4–), the
expansion and closing time of the fusion pore are longer, suggesting
chaotropes can extend the duration of exocytosis compared with kosmotropic
anions (e.g., Cl–). At a concentration of 30 mM,
the two parameters (e.g., t1/2 and tfall) that define the duration of exocytosis
vary with the Hofmeister series (Cl– < Br– < NO3– ≤ ClO4– < SCN–). More interestingly,
fewer (e.g., Nfoot/Nevents) and smaller (e.g., Ifoot) prespike events are observed when chaotropes are counterions in
the stimulation solution, and the values can be sorted by the reverse
Hofmeister series (Cl– ≥ Br– > NO3– > ClO4– > SCN–). Based on ion specificity,
an adsorption-repulsion
mechanism, we suggest that the exocytotic Hofmeister series effect
originates from a looser swelling lipid bilayer structure due to the
adsorption and electrostatic repulsion of chaotropes on the hydrophobic
portion of the membrane. Our results provide a chemical link between
the Hofmeister series and the cellular process of neurotransmitter
release via exocytosis and provide a better physical framework to
understand this important phenomenon.
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Affiliation(s)
- Xiulan He
- Department of Chemistry and Molecular Biology, University of Gothenburg, 41296 Gothenburg, Sweden
| | - Andrew G Ewing
- Department of Chemistry and Molecular Biology, University of Gothenburg, 41296 Gothenburg, Sweden
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8
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Ha Y, Kwon JH. Effects of lipid membrane composition on the distribution of biocidal guanidine oligomer with solid supported lipid membranes. RSC Adv 2020; 10:22343-22351. [PMID: 35514581 PMCID: PMC9054620 DOI: 10.1039/d0ra03108a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/04/2020] [Indexed: 11/21/2022] Open
Abstract
Polyhexamethylene guanidine (PHMG) is a cationic antimicrobial oligomer that has been used prevalently over the past few decades. However, due to the lack of inhalation toxicity assessment of PHMG, it has caused severe health damage, including fatal lung fibrosis, after being used as one of the major active ingredients of humidifier disinfectants in Korea. Because the first step of the entry of PHMG into airway is its association with cell membranes, the distribution of PHMG between lipid membranes and water is very important to know the depositional flux in the respiratory systems and related toxic mechanisms. We developed a quantitative method to determine the distribution constant (Klipw) of PHMG between solid supported lipid membranes and water and evaluated the effects of lipid membrane compositions on the Klipw of PHMG. PHMG accumulated into anionic lipid membranes rapidly compared to into cationic or zwitterionic lipid membranes, suggesting fast adsorption of PHMG onto anionic lipid head groups. Klipw values with anionic/zwitterionic lipid mixtures were higher than Klipw values with anionic lipids only, potentially due to the later phase separation after preferential interaction between PHMG and anionic lipids in lipid mixtures. In addition, Klipw values increased with increasing single acyl chain lipid content in unsaturated lipids and decreasing cholesterol content. These results imply that changes in lipid spontaneous curvature and lipid bilayer packing density also affect the membrane distribution of PHMG. This study experimentally determined the Klipw of PHMG and assessed the effects of lipid membrane composition on Klipw values.![]()
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Affiliation(s)
- Yeonjeong Ha
- Division of Environmental Science and Ecological Engineering, Korea University 145 Anam-ro Seongbuk-gu Seoul 02841 Republic of Korea +82 2 3290 3041
| | - Jung-Hwan Kwon
- Division of Environmental Science and Ecological Engineering, Korea University 145 Anam-ro Seongbuk-gu Seoul 02841 Republic of Korea +82 2 3290 3041
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9
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Xia Z, Lau BLT. Mitigating effects of osmolytes on the interactions between nanoparticles and supported lipid bilayer. J Colloid Interface Sci 2020; 568:1-7. [PMID: 32070850 DOI: 10.1016/j.jcis.2020.02.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 10/25/2022]
Abstract
To maintain osmotic balance, cells usually produce neutral solutes (i.e., osmolytes), together with charged species to cope with salinity stress. Osmolytes are known to be important in stabilizing/destabilizing macromolecules (e.g., proteins) via depletion /accumulation around their surfaces. To better understand the physiological fate of nanoparticles (NPs), we investigated the effect of osmolytes [(urea and trimethylamine N-oxide (TMAO)] and specific anions (NO3- and F-) on the interactions between NPs and supported lipid bilayers (SLBs). Carboxylated polystyrene NPs (60 nm) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) were chosen as model NPs and lipid. Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to quantify NP deposition dynamics. Microscale thermophoresis (MST) was used to characterize the affinity between DOPC vesicles (or NPs) and osmolytes. Our results show that osmolytes are capable of protecting SLBs from NP-induced disruption. Upon NP deposition onto supported vesicle layers (SVLs), the leakage of encapsulated dyes decreased with the addition of osmolytes. The combination of kosmotropes (TMAO and F-) are more efficient than that of chaotropes (urea and NO3-) in weakening the hydrophobic interaction between NPs and SLBs by preferential binding to NPs and/or SLBs.
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Affiliation(s)
- Zehui Xia
- Department of Civil & Environmental Engineering, University of Massachusetts Amherst, 130 Natural Resources Road, Amherst, MA 01003, USA
| | - Boris L T Lau
- Department of Civil & Environmental Engineering, University of Massachusetts Amherst, 130 Natural Resources Road, Amherst, MA 01003, USA.
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10
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Li S, Wu L, Zhang X, Jiang X. The Structure of Water Bonded to Phosphate Groups at the Electrified Zwitterionic Phospholipid Membranes/Aqueous Interface. Angew Chem Int Ed Engl 2020; 59:6627-6630. [DOI: 10.1002/anie.202000511] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Shanshan Li
- State Key Laboratory of Electroanalytical ChemistryChangchun Institute of Applied ChemistryChinese Academy of Sciences Changchun 130022, Jilin China
- University of Science and Technology of China Hefei Anhui 230029 P. R. China
| | - Lie Wu
- State Key Laboratory of Electroanalytical ChemistryChangchun Institute of Applied ChemistryChinese Academy of Sciences Changchun 130022, Jilin China
| | - Xiaofei Zhang
- State Key Laboratory of Electroanalytical ChemistryChangchun Institute of Applied ChemistryChinese Academy of Sciences Changchun 130022, Jilin China
- University of Science and Technology of China Hefei Anhui 230029 P. R. China
| | - Xiue Jiang
- State Key Laboratory of Electroanalytical ChemistryChangchun Institute of Applied ChemistryChinese Academy of Sciences Changchun 130022, Jilin China
- University of Science and Technology of China Hefei Anhui 230029 P. R. China
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11
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Li S, Wu L, Zhang X, Jiang X. The Structure of Water Bonded to Phosphate Groups at the Electrified Zwitterionic Phospholipid Membranes/Aqueous Interface. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Shanshan Li
- State Key Laboratory of Electroanalytical ChemistryChangchun Institute of Applied ChemistryChinese Academy of Sciences Changchun 130022, Jilin China
- University of Science and Technology of China Hefei Anhui 230029 P. R. China
| | - Lie Wu
- State Key Laboratory of Electroanalytical ChemistryChangchun Institute of Applied ChemistryChinese Academy of Sciences Changchun 130022, Jilin China
| | - Xiaofei Zhang
- State Key Laboratory of Electroanalytical ChemistryChangchun Institute of Applied ChemistryChinese Academy of Sciences Changchun 130022, Jilin China
- University of Science and Technology of China Hefei Anhui 230029 P. R. China
| | - Xiue Jiang
- State Key Laboratory of Electroanalytical ChemistryChangchun Institute of Applied ChemistryChinese Academy of Sciences Changchun 130022, Jilin China
- University of Science and Technology of China Hefei Anhui 230029 P. R. China
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12
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Abstract
Here, we present a protocol for the functional characterization of the H+-coupled human peptide transporter PepT1 and sufficient notes to transfer the protocol to the Na+-coupled sugar transporter SGLT1, the organic cation transporter OCT2, the Na+/Ca2+ exchanger NCX, and the neuronal glutamate transporter EAAT3.The assay was developed for the commercially available SURFE2R N1 instrument (Nanion Technologies GmbH) which applies solid supported membrane (SSM)-based electrophysiology. This technique is widely used for the functional characterization of membrane transporters with more than 100 different transporters characterized so far. The technique is cost-effective, easy to use, and capable of high-throughput measurements.SSM-based electrophysiology utilizes SSM-coated gold sensors to physically adsorb membrane vesicles containing the protein of interest. A fast solution exchange provides the substrate and activates transport. For the measurement of PepT1 activity, we applied a peptide concentration jump to activate H+/peptide symport. Proton influx charges the sensor. A capacitive current is measured reflecting the transport activity of PepT1 . Multiple measurements on the same sensor allow for comparison of transport activity under different conditions. Here, we determine EC50 for PepT1-mediated glycylglycine transport and perform an inhibition experiment using the specific peptide inhibitor Lys[Z(NO2)]-Val.
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13
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Mikušević V, Schrecker M, Kolesova N, Patiño-Ruiz M, Fendler K, Hänelt I. A channel profile report of the unusual K + channel KtrB. J Gen Physiol 2019; 151:1357-1368. [PMID: 31624134 PMCID: PMC6888753 DOI: 10.1085/jgp.201912384] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 09/03/2019] [Accepted: 09/27/2019] [Indexed: 11/20/2022] Open
Abstract
KtrAB is a key player in bacterial K+ uptake required for K+ homeostasis and osmoadaptation. The system is unique in structure and function. It consists of the K+-translocating channel subunit KtrB, which forms a dimer in the membrane, and the soluble regulatory subunit KtrA, which attaches to the cytoplasmic side of the dimer as an octameric ring conferring Na+ and ATP dependency to the system. Unlike most K+ channels, KtrB lacks the highly conserved T(X)GYG selectivity filter sequence. Instead, only a single glycine residue is found in each pore loop, which raises the question of how selective the ion channel is. Here, we characterized the KtrB subunit from the Gram-negative pathogen Vibrio alginolyticus by isothermal titration calorimetry, solid-supported membrane-based electrophysiology, whole-cell K+ uptake, and ACMA-based transport assays. We found that, despite its simple selectivity filter, KtrB selectively binds K+ with micromolar affinity. Rb+ and Cs+ bind with millimolar affinities. However, only K+ and the poorly binding Na+ are efficiently translocated, based on size exclusion by the gating loop. Importantly, the physiologically required K+ over Na+ selectivity is provided by the channel's high affinity for potassium, which interestingly results from the presence of the sodium ions themselves. In the presence of the KtrA subunit, sodium ions further decrease the Michaelis-Menten constant for K+ uptake from milli- to micromolar concentrations and increase the Vmax, suggesting that Na+ also facilitates channel gating. In conclusion, high binding affinity and facilitated K+ gating allow KtrAB to function as a selective K+ channel.
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Affiliation(s)
- Vedrana Mikušević
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Marina Schrecker
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Natalie Kolesova
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Miyer Patiño-Ruiz
- Department of Biophysical Chemistry, Max Planck Institute for Biophysics, Frankfurt, Germany
| | - Klaus Fendler
- Department of Biophysical Chemistry, Max Planck Institute for Biophysics, Frankfurt, Germany
| | - Inga Hänelt
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany
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14
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Melcrová A, Pokorna S, Vošahlíková M, Sýkora J, Svoboda P, Hof M, Cwiklik L, Jurkiewicz P. Concurrent Compression of Phospholipid Membranes by Calcium and Cholesterol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:11358-11368. [PMID: 31393734 DOI: 10.1021/acs.langmuir.9b00477] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Regulation of cell metabolism, membrane fusion, association of proteins with cellular membranes, and cellular signaling altogether would not be possible without Ca2+ ions. The distribution of calcium within the cell is uneven with the negatively charged inner leaflet of the plasma membrane being one of the primary targets of its accumulation. Therefore, we decided to map the influence of Ca2+ on the properties of lipid bilayers closely resembling natural lipid membranes. We combined fluorescence spectroscopy (analysis of time-resolved emission spectra of Laurdan probe and derived parameters: integrated relaxation time related to local lipid mobility, and total emission shift reflecting membrane polarity and hydration) with molecular dynamics simulations to determine the effect of the increasing CaCl2 concentration on model lipid membranes containing POPC, POPS, and cholesterol. On top of that, the impact of calcium on the plasma membranes isolated from HEK293 cells was investigated using the steady-state fluorescence of Laurdan. We found that calcium increases rigidity of all the model lipid membranes used, elevates their thickness, increases lipid packing and ordering, and impedes the local lipid mobility. All these effects were to a great extent similar to those elicited by cholesterol. However, the changes of the membrane properties induced by calcium and cholesterol seem largely independent from each other. At sufficiently high concentrations of calcium or cholesterol, the steric effects hindered a further alteration of membrane organization, i.e., the compressibility limit of membrane structures was reached. We found no indication for mutual interaction between Ca2+ and cholesterol, nor competition of Ca2+ ions and hydroxyl groups of cholesterol for binding to phospholipids. Fluorescence measurements indicated that Ca2+ adsorption decreases mobility within the carbonyl region of model bilayers more efficiently than monovalent ions do (Ca2+ ≫ Li+ > Na+ > K+ > Cs+). The effects of calcium ions were to a great extent mitigated in the plasma membranes isolated from HEK293 cells when compared to the model lipid membranes. Noticeably, the plasma membranes showed remarkably higher resistance toward rigidification induced by calcium ions even when compared with the model membranes containing cholesterol.
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Affiliation(s)
- Adéla Melcrová
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , 182 23 Prague 8 , Czech Republic
| | - Sarka Pokorna
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , 182 23 Prague 8 , Czech Republic
| | - Miroslava Vošahlíková
- Institute of Physiology of the Czech Academy of Sciences , Vídeňská 1083 , 14220 Prague 4 , Czech Republic
| | - Jan Sýkora
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , 182 23 Prague 8 , Czech Republic
| | - Petr Svoboda
- Institute of Physiology of the Czech Academy of Sciences , Vídeňská 1083 , 14220 Prague 4 , Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , 182 23 Prague 8 , Czech Republic
| | - Lukasz Cwiklik
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , 182 23 Prague 8 , Czech Republic
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , 166 10 Prague 6 , Czech Republic
| | - Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , 182 23 Prague 8 , Czech Republic
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15
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Garcia A, Pochinda S, Elgaard-Jørgensen PN, Khandelia H, Clarke RJ. Evidence for ATP Interaction with Phosphatidylcholine Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:9944-9953. [PMID: 31291108 DOI: 10.1021/acs.langmuir.9b01240] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
ATP is a fundamental intracellular molecule and is thought to diffuse freely throughout the cytosol. Evidence obtained from nucleotide-sensing sarcolemmal ion channels and red blood cells, however, suggest that ATP is compartmentalized or buffered, especially beneath the sarcolemma, but no definitive mechanism for restricted diffusion or potential buffering system has been postulated. In this study, we provide evidence from alterations to membrane dipole potential, membrane conductance, changes in enthalpy of phospholipid phase transition, and from free energy calculations that ATP associates with phospholipid bilayers. Furthermore, all-atom molecular dynamics simulations show that ATP can form aggregates in the aqueous phase at high concentrations. ATP interaction with membranes provides a new model to understand the diffusion of ATP through the cell. Coupled with previous reports of diffusion restriction in the subsarcolemmal space, these findings support the existence of compartmentalized or buffered pools of ATP.
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Affiliation(s)
- Alvaro Garcia
- School of Life Sciences , University of Technology Sydney , Ultimo , NSW 2007 , Australia
| | - Simon Pochinda
- PHYLIFE: Physical Life Sciences at SDU, Department of Physics, Chemistry and Pharmacy and MEMPHYS: Center for Biomembrane Physics , University of Southern Denmark , DK-5230 Odense M , Denmark
| | - Paninnguaq N Elgaard-Jørgensen
- PHYLIFE: Physical Life Sciences at SDU, Department of Physics, Chemistry and Pharmacy and MEMPHYS: Center for Biomembrane Physics , University of Southern Denmark , DK-5230 Odense M , Denmark
| | - Himanshu Khandelia
- PHYLIFE: Physical Life Sciences at SDU, Department of Physics, Chemistry and Pharmacy and MEMPHYS: Center for Biomembrane Physics , University of Southern Denmark , DK-5230 Odense M , Denmark
| | - Ronald J Clarke
- School of Chemistry , University of Sydney , Sydney , NSW 2006 , Australia
- The University of Sydney Nano Institute , Sydney , NSW 2006 , Australia
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16
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Kuznietsova HM, Hurmach VV, Bychko AV, Tykhoniuk OI, Milokhov DS, Khilya OV, Volovenko YM, Rybalchenko VK. Synthesis and biological activity of 4-amino-3-chloro-1 H-pyrrole-2,5-diones. In Silico Pharmacol 2019; 7:2. [PMID: 31032168 DOI: 10.1007/s40203-019-0051-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/04/2019] [Indexed: 12/22/2022] Open
Abstract
4-Amino-3-chloro-1H-pyrrole-2,5-dione derivatives were designed and synthesized as potential tyrosine kinase inhibitors. One of them has been shown to inhibit growth of cancer cell lines and in vivo tumors. To determine the impact of side groups on biological activity the ability of different 4-amino-3-chloro-1H-pyrrole-2,5-diones to interact with ATP-binding domains of growth factor receptors and with model cell membranes were aimed to be discovered. The methods of molecular docking, short-molecular dynamics (in silico) and non-steady cyclic current-voltage characteristics (in vitro) were used. Five 4-amino-3-chloro-1H-pyrrole-2,5-diones were synthesized from 3,4-dichloro-1H-pyrrole-2,5-diones. All of them demonstrated the potential ability to form complexes with ATP-binding domains of EGFR and VEGFR2. These complexes were more stable compared to those with ANP. 4-Amino-3-chloro-1H-pyrrole-2,5-diones while interact with different bilayer lipid membranes caused an increase of their specific conductance and electric capacity, demonstrating the certain disturbance in lipid packing. Obtained data allowed us to suggest that proposed chemicals can interact with the surface of lipid bilayer, do likely intercalate into the membrane and form stable complexes with EGFR and VEGFR2. So, the prospect of developed chemicals to be effective EGFR and VEGFR2 inhibitors and therefore realize antitumor activity was concluded.
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Affiliation(s)
- Halyna M Kuznietsova
- 1Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska St., Kiev, 01601 Ukraine
| | - Vasyl V Hurmach
- 1Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska St., Kiev, 01601 Ukraine
| | - Andriy V Bychko
- 2Bogomolets National Medical University, 13, T. Shevchenko Blvd, Kiev, 01601 Ukraine
| | - Olena I Tykhoniuk
- 1Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska St., Kiev, 01601 Ukraine
| | - Demyd S Milokhov
- 1Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska St., Kiev, 01601 Ukraine
| | - Olga V Khilya
- 1Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska St., Kiev, 01601 Ukraine
| | - Yulian M Volovenko
- 1Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska St., Kiev, 01601 Ukraine
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17
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Cebecauer M, Amaro M, Jurkiewicz P, Sarmento MJ, Šachl R, Cwiklik L, Hof M. Membrane Lipid Nanodomains. Chem Rev 2018; 118:11259-11297. [PMID: 30362705 DOI: 10.1021/acs.chemrev.8b00322] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Lipid membranes can spontaneously organize their components into domains of different sizes and properties. The organization of membrane lipids into nanodomains might potentially play a role in vital functions of cells and organisms. Model membranes represent attractive systems to study lipid nanodomains, which cannot be directly addressed in living cells with the currently available methods. This review summarizes the knowledge on lipid nanodomains in model membranes and exposes how their specific character contrasts with large-scale phase separation. The overview on lipid nanodomains in membranes composed of diverse lipids (e.g., zwitterionic and anionic glycerophospholipids, ceramides, glycosphingolipids) and cholesterol aims to evidence the impact of chemical, electrostatic, and geometric properties of lipids on nanodomain formation. Furthermore, the effects of curvature, asymmetry, and ions on membrane nanodomains are shown to be highly relevant aspects that may also modulate lipid nanodomains in cellular membranes. Potential mechanisms responsible for the formation and dynamics of nanodomains are discussed with support from available theories and computational studies. A brief description of current fluorescence techniques and analytical tools that enabled progress in lipid nanodomain studies is also included. Further directions are proposed to successfully extend this research to cells.
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Affiliation(s)
- Marek Cebecauer
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Mariana Amaro
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Maria João Sarmento
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Lukasz Cwiklik
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
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18
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Meynaq MYK, Lindholm-Sethson B, Tesfalidet S. Interaction of anions with lipid cubic phase membranes, an electrochemical impedance study. J Colloid Interface Sci 2018; 528:263-270. [PMID: 29859451 DOI: 10.1016/j.jcis.2018.05.071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 11/30/2022]
Abstract
HYPOTHESIS Electrochemical impedance spectroscopy is useful to monitor anionic interactions with a Lipid Cubic Phase, as previously demonstrated for cationic interaction (Khani Meynaq et al., 2016). It was expected that the smaller hydrophilic anions, acetate and chloride, would interact differently than the large tryptophan anion with its hydrophobic tail. EXPERIMENT The impedance measurements enabled estimation of resistances and capacitances of a freestanding lipid cubic phase membrane at exposure to 4 and 40 mM solutions of NaCl, NaOAc and NaTrp. Small-angle X-ray scattering was used for cubic phase identification and to track structural changes within the cubic phase when exposed to the different electrolytes. FINDINGS The membrane resistance increases at exposure to the electrolytes in the order Cl- < OAc- < Trp-. The membrane resistance decreases with time at exposure to the hydrophilic anions and increases with time at Trp- exposure. The membrane capacitances were lower for NaTrp compared to NaCl and NaOAc at the corresponding concentrations which is consistent with the results from SAXRD. It is concluded that Trp- ions do not enter the aqueous channels of the cubic phase but are strongly adsorbed to the membrane/electrolyte interface leading to large alteration of the lipid phase structure and a high membrane resistance.
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19
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Kotyńska J, Figaszewski ZA. Binding of trivalent metal ions (Al 3+, In 3+, La 3+) with phosphatidylcholine liposomal membranes investigated by microelectrophoresis. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:70. [PMID: 29802496 DOI: 10.1140/epje/i2018-11679-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
Interactions between trivalent metal ions (Al3+, In3+, La3+) and phosphatidylcholine (PC) liposomes are studied by microelectrophoresis. The dependence of the PC membrane surface charge density and zeta potential on [Formula: see text] ([Formula: see text] range from 2 to 10) of the aqueous metal chloride solutions is determined. The obtained results indicate the adsorption of Al3+, In3+ and La3+ ions on phosphatidylcholine model membranes, leading to changes in the electrical properties of the membranes. The theoretical considerations on equilibria occurring between phosphatidylcholine liposomal membrane and trivalent metal ions are presented. A mathematical model describing the interactions in a quantitative way is proposed.
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Affiliation(s)
- Joanna Kotyńska
- Institute of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245, Bialystok, Poland.
| | - Zbigniew A Figaszewski
- Institute of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245, Bialystok, Poland
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20
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When a transmembrane channel isn't, or how biophysics and biochemistry (mis)communicate. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1099-1104. [PMID: 29408340 DOI: 10.1016/j.bbamem.2018.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 11/21/2022]
Abstract
Annexins are a family of soluble proteins that bind to acidic phospholipids such as phosphatidylserine in a calcium-dependent manner. The archetypical member of the annexin family is annexin A5. For many years, its function remained unknown despite the availability of a high-resolution structure. This, combined with the observations of specific ion conductance in annexin-bound membranes, fueled speculations about the possible membrane-spanning forms of annexins that functioned as ion channels. The channel hypothesis remained controversial and did not gather sufficient evidence to become accepted. Yet, it continues to draw attention as a framework for interpreting indirect (e.g., biochemical) data. The goal of the mini-review is to examine the data on annexin-lipid interactions from the last ~30 years from the point of view of the controversy between the two lines of inquiry: the well-characterized peripheral assembly of the annexins at membranes vs. their putative transmembrane insertion. In particular, the potential role of lipid rearrangements induced by annexin binding is highlighted.
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21
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Adams EM, Verreault D, Jayarathne T, Cochran RE, Stone EA, Allen HC. Surface organization of a DPPC monolayer on concentrated SrCl 2 and ZnCl 2 solutions. Phys Chem Chem Phys 2018; 18:32345-32357. [PMID: 27854367 DOI: 10.1039/c6cp06887a] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transition metals are known to be enriched in organic-coated marine aerosols, but the impact these cations have on their surface properties is not well understood. Here the effect of Zn2+ enrichment on the surface properties of a dipalmitoylphosphatidylcholine (DPPC) monolayer was investigated and compared to that of the alkaline earth metal Sr2+, an ion not enriched in aerosols. Phase behavior of the DPPC film on concentrated aqueous solutions was probed with surface pressure-area isotherms while domain morphology was monitored with Brewster angle microscopy (BAM). Infrared reflection-absorption spectroscopy (IRRAS) and vibrational sum frequency generation (VSFG) spectroscopy were used to assess the impact of cations on the conformation and orientation of alkyl chains as well as the hydration state of the carbonyl and phosphatidylcholine (PC) moieties. Results of compression isotherms and BAM show that Zn2+ strongly interacts with DPPC molecules, and induces condensation of the monolayer while Sr2+ only weakly interacts with the monolayer in expanded phases. Conformational order and orientation of alkyl chains in the condensed phase are not significantly altered by either cation. IRRAS indicates that Sr2+ has weak interactions with the PC headgroup. Zn2+ ions cause dehydration of carbonyl groups and binds to the phosphate group in a 2 : 1 bridging complex. Findings here suggest that Sr2+ is not enriched in aerosols because it behaves similar to a monovalent ion and only weakly interacts with the monolayer, while enrichment of Zn2+ is due to strong binding to the lipid film.
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Affiliation(s)
- Ellen M Adams
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA.
| | - Dominique Verreault
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA.
| | | | - Richard E Cochran
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - Elizabeth A Stone
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA
| | - Heather C Allen
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA.
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22
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Abstract
Biomembranes assemble and operate at the interface with electrolyte solutions. Interactions between ions in solutions and the lipid affect the membrane structure, dynamics and electrostatic potential. In this article, I review some of the experimental and computational methods that are used to study membrane–ions interactions. Experimental methods that account for membrane–ion interactions directly and indirectly are presented first. Then, studies in which molecular dynamics simulations were used to gain an understanding of membrane–ion interactions are surveyed. Finally, the current view on membrane–ion interactions and their significance is briefly discussed.
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Affiliation(s)
- Ran Friedman
- Department of Chemistry and Biomedical Sciences and Centre of Excellence "Biomaterials Chemistry", Linnæus University, Kalmar, Sweden.
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23
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Kong Q, Zhuang W, Li G, Jiang Q, Wang Y. Cation–anion interaction-directed formation of functional vesicles and their biological application for nucleus-specific imaging. NEW J CHEM 2018. [DOI: 10.1039/c8nj01503a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A strategy for the construction of counterion-induced vesicles in aqueous media has been described. Furthermore, the imidazolium salt with an AIE fluorophore exhibits highly specific nucleus imaging in the living cells.
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Affiliation(s)
- Qunshou Kong
- National Engineering Research Center for Biomaterials
- Sichuan University
- Chengdu 610064
- China
| | - Weihua Zhuang
- National Engineering Research Center for Biomaterials
- Sichuan University
- Chengdu 610064
- China
| | - Gaocan Li
- National Engineering Research Center for Biomaterials
- Sichuan University
- Chengdu 610064
- China
| | - Qing Jiang
- National Engineering Research Center for Biomaterials
- Sichuan University
- Chengdu 610064
- China
| | - Yunbing Wang
- National Engineering Research Center for Biomaterials
- Sichuan University
- Chengdu 610064
- China
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24
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Fernández–d'Arlas B, Huertos MÁ, Müller AJ. Ion-macromolecule interactions studied with model polyurethanes. J Colloid Interface Sci 2018; 509:102-112. [DOI: 10.1016/j.jcis.2017.08.099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 08/29/2017] [Accepted: 08/30/2017] [Indexed: 11/25/2022]
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25
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Effects of Ca2+, Glu and GABA on hBest1 and composite hBest1/POPC surface films. Colloids Surf B Biointerfaces 2018; 161:192-199. [DOI: 10.1016/j.colsurfb.2017.10.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 10/11/2017] [Accepted: 10/17/2017] [Indexed: 12/22/2022]
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26
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Abstract
Functional characterization of transport proteins using conventional electrophysiology can be challenging, especially for low turnover transporters or transporters from bacteria and intracellular compartments. Solid-supported membrane (SSM)-based electrophysiology is a sensitive and cell-free assay technique for the characterization of electrogenic membrane proteins. Purified proteins reconstituted into proteoliposomes or membrane vesicles from cell culture or native tissues are adsorbed to the sensor holding an SSM. A substrate or a ligand is applied via rapid solution exchange. The electrogenic transporter activity charges the sensor, which is recorded as a transient current. The high stability of the SSM allows cumulative measurements on the same sensor using different experimental conditions. This allows the determination of kinetic properties including EC50, IC50, Km, KD, and rate constants of electrogenic reactions. About 100 different transporters have been measured so far using this technique, among them symporters, exchangers, uniporters, ATP-, redox-, and light-driven ion pumps, as well as receptors and ion channels. Different instruments apply this technique: the laboratory setups use a closed flow-through arrangement, while the commercially available SURFE2R N1 resembles a pipetting robot. For drug screening purposes high-throughput systems, such as the SURFE2R 96SE enable the simultaneous measurement of up to 96 sensors.
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Affiliation(s)
- Andre Bazzone
- Max Planck Institute of Biophysics, Frankfurt/Main, Germany; Nanion Technologies GmbH, Munich, Germany
| | | | - Klaus Fendler
- Max Planck Institute of Biophysics, Frankfurt/Main, Germany.
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27
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Leontidis E. Investigations of the Hofmeister series and other specific ion effects using lipid model systems. Adv Colloid Interface Sci 2017; 243:8-22. [PMID: 28395857 DOI: 10.1016/j.cis.2017.04.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 04/02/2017] [Indexed: 11/28/2022]
Abstract
From the ion point-of-view specific ion effects (SIE) arise as an interplay of ionic size and shape and charge distribution. However in aqueous systems SIE invariably involve water, and at surfaces they involve both interacting surface groups and local fields emanating from the surface. In this review we highlight the fundamental importance of ionic size and hydration on SIE, properties which encompass all types of interacting forces and ion-pairing phenomena and make the Hofmeister or lyotropic series of ions pertinent to a broad range of systems and phenomena. On the other hand ionic hydrophobicity and complexation capacity also determine ionic behavior in a variety of contexts. Over the years we have carried out carefully designed experiments on a few selected soft matter model systems, most involving zwitterionic phospholipids, to assess the importance of fundamental ionic and interfacial properties on ion specific effects. By tuning down direct Coulomb interactions, working with different interfacial geometries, and carefully tuning ion-lipid headgroup interactions it is possible to assess the importance of different parameters contributing to ion specific behavior. We argue that the majority of specific ion effects involving relatively simple soft matter systems can be at least qualitatively understood and demystified.
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28
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Gurnev PA, Roark TC, Petrache HI, Sodt AJ, Bezrukov SM. Cation-Selective Channel Regulated by Anions According to Their Hofmeister Ranking. Angew Chem Int Ed Engl 2017; 56:3506-3509. [PMID: 28198582 PMCID: PMC5518747 DOI: 10.1002/anie.201611335] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/05/2017] [Indexed: 11/08/2022]
Abstract
Specificity of small ions, the Hofmeister ranking, is long-known and has many applications including medicine. Yet it evades consistent theoretical description. Here we study the effect of Hofmeister anions on gramicidin A channels in lipid membranes. Counterintuitively, we find that conductance of this perfectly cation-selective channel increases about two-fold in the H2 PO4-
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Affiliation(s)
- Philip A Gurnev
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bldg. 9, Rm 1 N-124B, Bethesda, MD, 20892, USA
| | - Torri C Roark
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bldg. 9, Rm 1 N-124B, Bethesda, MD, 20892, USA
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Horia I Petrache
- Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Alexander J Sodt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bldg. 9, Rm 1 N-124B, Bethesda, MD, 20892, USA
| | - Sergey M Bezrukov
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bldg. 9, Rm 1 N-124B, Bethesda, MD, 20892, USA
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29
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Gurnev PA, Roark TC, Petrache HI, Sodt AJ, Bezrukov SM. Cation‐Selective Channel Regulated by Anions According to Their Hofmeister Ranking. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Philip A. Gurnev
- Eunice Kennedy Shriver National Institute of Child Health and Human Development NIH Bldg. 9, Rm 1 N-124B Bethesda MD 20892 USA
| | - Torri C. Roark
- Eunice Kennedy Shriver National Institute of Child Health and Human Development NIH Bldg. 9, Rm 1 N-124B Bethesda MD 20892 USA
- Department of Physics Indiana University Purdue University Indianapolis Indianapolis IN 46202 USA
| | - Horia I. Petrache
- Department of Physics Indiana University Purdue University Indianapolis Indianapolis IN 46202 USA
| | - Alexander J. Sodt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development NIH Bldg. 9, Rm 1 N-124B Bethesda MD 20892 USA
| | - Sergey M. Bezrukov
- Eunice Kennedy Shriver National Institute of Child Health and Human Development NIH Bldg. 9, Rm 1 N-124B Bethesda MD 20892 USA
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30
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Effect of Sodium and Chloride Binding on a Lecithin Bilayer. A Molecular Dynamics Study. MEMBRANES 2017; 7:membranes7010005. [PMID: 28125062 PMCID: PMC5371966 DOI: 10.3390/membranes7010005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/12/2017] [Accepted: 01/14/2017] [Indexed: 01/17/2023]
Abstract
The effect of ion binding on the structural, mechanical, dynamic and electrostatic properties of a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer in a 0.5 M aqueous NaCl solution is investigated using classical atomistic molecular dynamics simulation with different force-field descriptions for ion-ion and ion-lipid interactions. Most importantly, the repulsive Lennard-Jones parameters for the latter were modified, such that approximately similar binding of cations and anions to the lipid membrane is achieved. This was done to qualitatively improve the apparent ion-lipid binding constants obtained from simulations with the original force field (Berger lipids and GROMOS87 ions in combination with the SPC water model) in comparison to experimental data. Furthermore, various parameters characterizing membrane structure, elasticity, order and dynamics are analyzed. It is found that ion binding as observed in simulations involving the modified in comparison to the original force-field description leads to: (i) a smaller salt-induced change in the area per lipid, which is in closer agreement with the experiment; (ii) a decrease in the area compressibility and bilayer thickness to values comparable to a bilayer in pure water; (iii) lipid deuterium order parameters and lipid diffusion coefficients on nanosecond timescales that are very similar to the values for a membrane in pure water. In general, salt effects on the structural properties of a POPC bilayer in an aqueous sodium-chloride solution appear to be reproduced reasonably well by the new force-field description. An analysis of membrane-membrane disjoining pressure suggests that the smaller salt-induced change in area per lipid induced by the new force-field description is not due to the alteration of membrane-associated net charge, but must rather be understood as a consequence of ion-specific effects on the arrangement of lipid molecules.
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Lin ST, Lin CS, Chang YY, Whitten AE, Sokolova A, Wu CM, Ivanov VA, Khokhlov AR, Tung SH. Effects of Alkali Cations and Halide Anions on the Self-Assembly of Phosphatidylcholine in Oils. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:12166-12174. [PMID: 27802053 DOI: 10.1021/acs.langmuir.6b03449] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The interactions between ions and phospholipids are closely associated with the structures and functions of cell membrane. Instead of conventional aqueous systems, we systematically investigated the effects of inorganic ions on the self-assembly of lecithin, a zwitterionic phosphatidylcholine, in cyclohexane. Previous studies have shown that addition of inorganic salts with specific divalent and trivalent cations can transform lecithin organosols into organogels. In this study, we focused on the effect of monovalent alkali halides. Fourier transform infrared spectroscopy was used to demonstrate that the binding strength of the alkali cations with the phosphate of lecithin is in the order Li+ > Na+ > K+. More importantly, the cation-phosphate interaction is affected by the paired halide anions, and the effect follows the series I- > Br- > Cl-. The salts of stronger interactions with lecithin, including LiCl, LiBr, LiI, and NaI, were found to induce cylindrical micelles sufficiently long to form organogels, while others remain organosols. A mechanism based on the charge density of ions and the enthalpy change of the ion exchange between alkali halides and lecithin headgroup is provided to explain the contrasting interactions and the effectiveness of the salts to induce organogelation.
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Affiliation(s)
- Shih-Ting Lin
- Institute of Polymer Science and Engineering, National Taiwan University , Taipei 10617, Taiwan
| | - Chen-Shin Lin
- Institute of Polymer Science and Engineering, National Taiwan University , Taipei 10617, Taiwan
| | - Ya-Ying Chang
- Institute of Polymer Science and Engineering, National Taiwan University , Taipei 10617, Taiwan
| | - Andrew E Whitten
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Anna Sokolova
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Chun-Ming Wu
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Viktor A Ivanov
- Faculty of Physics, Moscow State University , Moscow 119991, Russia
| | | | - Shih-Huang Tung
- Institute of Polymer Science and Engineering, National Taiwan University , Taipei 10617, Taiwan
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32
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Násztor Z, Bogár F, Dér A. The interfacial tension concept, as revealed by fluctuations. Curr Opin Colloid Interface Sci 2016. [DOI: 10.1016/j.cocis.2016.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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33
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Schwierz N, Horinek D, Sivan U, Netz RR. Reversed Hofmeister series—The rule rather than the exception. Curr Opin Colloid Interface Sci 2016. [DOI: 10.1016/j.cocis.2016.04.003] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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34
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Tadini-Buoninsegni F, Bartolommei G. Electrophysiological Measurements on Solid Supported Membranes. Methods Mol Biol 2016; 1377:293-303. [PMID: 26695041 DOI: 10.1007/978-1-4939-3179-8_26] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The solid supported membrane (SSM) represents a convenient model system for a biological membrane with the advantage of being mechanically so stable that solutions can be rapidly exchanged at the surface. The SSM consists of a hybrid alkanethiol-phospholipid bilayer supported by a gold electrode. Proteoliposomes, membrane vesicles, or membrane fragments containing the transport protein of interest are adsorbed on the SSM surface and are subjected to a rapid substrate concentration jump. The substrate concentration jump activates the protein and the charge displacement concomitant with its transport activity is recorded as a current transient. Since this technique is well suited for the functional characterization of electrogenic membrane transporters, it is expected to become a promising platform technology for drug screening and development.
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Affiliation(s)
| | - Gianluca Bartolommei
- Department of Chemistry "Ugo Schiff", University of Florence, 50019, Sesto Fiorentino, Italy
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35
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Catte A, Girych M, Javanainen M, Loison C, Melcr J, Miettinen MS, Monticelli L, Määttä J, Oganesyan VS, Ollila OHS, Tynkkynen J, Vilov S. Molecular electrometer and binding of cations to phospholipid bilayers. Phys Chem Chem Phys 2016; 18:32560-32569. [DOI: 10.1039/c6cp04883h] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The molecular electrometer – reorientation of lipid head due to bound charge – allows direct quantitative vetting of simulations against noninvasive NMR experiments; most simulation models overestimated lipid–cation affinities.
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36
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Tadini-Buoninsegni F, Moncelli MR, Peruzzi N, Ninham BW, Dei L, Nostro PL. Hofmeister effect of anions on calcium translocation by sarcoplasmic reticulum Ca(2+)-ATPase. Sci Rep 2015; 5:14282. [PMID: 26435197 PMCID: PMC4593048 DOI: 10.1038/srep14282] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/24/2015] [Indexed: 11/18/2022] Open
Abstract
The occurrence of Hofmeister (specific ion) effects in various membrane-related physiological processes is well documented. For example the effect of anions on the transport activity of the ion pump Na+, K+-ATPase has been investigated. Here we report on specific anion effects on the ATP-dependent Ca2+ translocation by the sarcoplasmic reticulum Ca2+-ATPase (SERCA). Current measurements following ATP concentration jumps on SERCA-containing vesicles adsorbed on solid supported membranes were carried out in the presence of different potassium salts. We found that monovalent anions strongly interfere with ATP-induced Ca2+ translocation by SERCA, according to their increasing chaotropicity in the Hofmeister series. On the contrary, a significant increase in Ca2+ translocation was observed in the presence of sulphate. We suggest that the anions can affect the conformational transition between the phosphorylated intermediates E1P and E2P of the SERCA cycle. In particular, the stabilization of the E1P conformation by chaotropic anions seems to be related to their adsorption at the enzyme/water and/or at the membrane/water interface, while the more kosmotropic species affect SERCA conformation and functionality by modifying the hydration layers of the enzyme.
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Affiliation(s)
| | - Maria Rosa Moncelli
- Department of Chemistry "Ugo Schiff", University of Florence, 50019 Sesto Fiorentino (Firenze), Italy
| | - Niccolò Peruzzi
- Department of Chemistry "Ugo Schiff", University of Florence, 50019 Sesto Fiorentino (Firenze), Italy.,CSGI, University of Florence, 50019 Sesto Fiorentino (Firenze), Italy
| | - Barry W Ninham
- Research School of Physical Sciences and Engineering, Australian National University, Canberra, Australia 0200
| | - Luigi Dei
- Department of Chemistry "Ugo Schiff", University of Florence, 50019 Sesto Fiorentino (Firenze), Italy.,CSGI, University of Florence, 50019 Sesto Fiorentino (Firenze), Italy
| | - Pierandrea Lo Nostro
- Department of Chemistry "Ugo Schiff", University of Florence, 50019 Sesto Fiorentino (Firenze), Italy.,CSGI, University of Florence, 50019 Sesto Fiorentino (Firenze), Italy
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37
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Pandiscia LA, Schweitzer-Stenner R. Coexistence of Native-Like and Non-Native Cytochrome c on Anionic Liposomes with Different Cardiolipin Content. J Phys Chem B 2015; 119:12846-59. [PMID: 26369421 DOI: 10.1021/acs.jpcb.5b07328] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We employed a combination of fluorescence, visible circular dichroism, and absorption spectroscopy to study the conformational changes of ferricytochrome c upon its binding to cardiolipin-containing small unilamellar vesicles. The measurements were performed as a function of the cardiolipin concentration, the cardiolipin content of the liposomes, and the NaCl concentration of the solvent. The data were analyzed with a novel model that combines a single binding step with a conformational equilibrium between native-like and non-native-like proteins bound to the membrane surface. The equilibrium between the two conformations, which themselves are comprised of structurally slightly different subconformations, shifts to the more non-native-like conformation with increasing cardiolipin concentration. For the binding isotherms described in this paper, we explicitly considered the enthalpic and entropic contributions of molecular crowding to protein binding at low lipid concentrations and high occupancy of the liposome surface. Increasing the CL content of liposomes increases the overall binding affinity but makes the conformational distribution much more susceptible to the influence of sodium and chloride ions, which shifts the equilibrium toward the more native-like state and directly inhibits binding, particularly to liposomes with 100% cardiolipin content. Spectroscopic evidence further suggests that a fraction of the non-native conformers adopts a pentacoordinated state similar to those obtained in class C peroxidases. On the basis of our results, we propose a hypothesis that describes the balance between facilitating and impeding forces controlling the peroxidase activity of cytochrome c in the inner membrane space of mitochondria.
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Affiliation(s)
- Leah A Pandiscia
- Department of Chemistry, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Reinhard Schweitzer-Stenner
- Department of Chemistry, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
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38
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Biophysical properties of cationic lipophosphoramidates: Vesicle morphology, bilayer hydration and dynamics. Colloids Surf B Biointerfaces 2015; 136:192-200. [PMID: 26398144 DOI: 10.1016/j.colsurfb.2015.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 08/10/2015] [Accepted: 09/06/2015] [Indexed: 02/04/2023]
Abstract
Cationic lipids are used to deliver genetic material to living cells. Their proper biophysical characterization is needed in order to design and control this process. In the present work we characterize some properties of recently synthetized cationic lipophosphoramidates. The studied compounds share the same structure of their hydrophobic backbone, but differ in their hydrophilic cationic headgroup, which is formed by a trimethylammonium, a trimethylarsonium or a dicationic moiety. Dynamic light scattering and cryo-transmission electron microscopy proves that the studied lipophosphoramidates create stable unilamellar vesicles. Fluorescence of polarity probe, Laurdan, analyzed using time-dependent fluorescence shift method (TDFS) and generalized polarization (GP) gives important information about the phase, hydration and dynamics of the lipophosphoramidate bilayers. While all of the compounds produced lipid bilayers that were sufficiently fluid for their potential application in gene therapy, their polarity/hydration and mobility was lower than for the standard cationic lipid - DOTAP. Mixing cationic lipophosphoramidates with DOPC helps to reduce this difference. The structure of the cationic headgroup has an important and complex influence on bilayer hydration and mobility. Both TDFS and GP methods are suitable for the characterization of cationic amphiphiles and can be used for screening of the newly synthesized compounds.
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39
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Wen Q, Chen JX, Tang YL, Wang J, Yang Z. Assessing the toxicity and biodegradability of deep eutectic solvents. CHEMOSPHERE 2015; 132:63-9. [PMID: 25800513 DOI: 10.1016/j.chemosphere.2015.02.061] [Citation(s) in RCA: 200] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/01/2015] [Accepted: 02/26/2015] [Indexed: 05/16/2023]
Abstract
Deep eutectic solvents (DESs) have emerged as a new type of promising ionic solvents with a broad range of potential applications. Although their ecotoxicological profile is still poorly known, DESs are generally regarded as "green" because they are composed of ammonium salts and H-bond donors (HBDs) which are considered to be eco-friendly. In this work, cholinium-based DESs comprised of choline chloride (ChCl) and choline acetate (ChAc) as the salt and urea (U), acetamide (A), glycerol (G) and ethylene glycol (EG) as the HBD were evaluated for their toxic effects on different living organisms such as Escherichia coli (a bacterium), Allium sativum (garlic, a plant) and hydra (an invertebrate), and their biodegradabilities were assessed by means of closed bottle tests. These DESs possessed an anti-bacterial property and exhibited inhibitory effects on the test organisms adopted, depending on the composition and concentration of the DES. The mechanism for the impact of DESs and their components on different living organisms can be associated to their interactions with the cellular membranes. Not all DESs can be considered readily biodegradable. By extending the limited knowledge about the toxicity and biodegradation of this particular solvent family, this investigation on DESs provides insight into our structure-based understanding of their ecotoxicological behavior.
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Affiliation(s)
- Qing Wen
- College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology, Shenzhen University, Shenzhen 518060, Guangdong, China
| | - Jing-Xin Chen
- College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology, Shenzhen University, Shenzhen 518060, Guangdong, China
| | - Yu-Lin Tang
- College of Life Sciences, Shenzhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, Guangdong, China
| | - Juan Wang
- College of Life Sciences, Shenzhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, Guangdong, China
| | - Zhen Yang
- College of Life Sciences, Shenzhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, Guangdong, China.
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40
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Rycovska-Blume A, Lü W, Andrade S, Fendler K, Einsle O. Structural and Functional Studies of NirC from Salmonella typhimurium. Methods Enzymol 2015; 556:475-97. [PMID: 25857796 DOI: 10.1016/bs.mie.2014.12.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
NirC is a pentameric transport system for monovalent anions that is expressed in the context of assimilatory nitrite reductase NirBD in a wide variety of enterobacterial species. A NirC pentamer contains individual pores in each protomer that mediate the passage of at least the nitrite [Formula: see text] and nitrate [Formula: see text] anions. As a member of the formate/nitrite transporter family of membrane transport proteins, NirC shares a range of structural and functional features with the formate channel FocA and the hydrosulfide channel AsrD (HSC). NirC from the enteropathogen Salmonella typhimurium has been studied by X-ray crystallography, proton uptake assays, and different electrophysiological techniques, and the picture that has emerged shows a fast and versatile transport system for nitrite that doubles as a defense system during the enteric life of the bacterium. Structural and functional assays are described, which shed light on the transport mechanism of this important molecular machine.
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Affiliation(s)
- Adriana Rycovska-Blume
- Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
| | - Wei Lü
- Institute for Biochemistry, Albert-Ludwigs-University Freiburg, Freiburg im Breisgau, Germany
| | - Susana Andrade
- Institute for Biochemistry, Albert-Ludwigs-University Freiburg, Freiburg im Breisgau, Germany; BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg im Breisgau, Germany
| | - Klaus Fendler
- Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Oliver Einsle
- Institute for Biochemistry, Albert-Ludwigs-University Freiburg, Freiburg im Breisgau, Germany; BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg im Breisgau, Germany
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41
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Tisor O, Muzzio M, Lopez D, Lee S. Adaptability of monoglyceride-induced crystallization of K2SO4: effect of various anions and lipid chain splay. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2112-2119. [PMID: 25645981 DOI: 10.1021/la5049419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding the interaction of a surfactant assembly with surrounding ionic compositions is critical in controlling the nanostructure formed by amphiphilic systems. In this study, we investigated the influence of specific anions upon the character of the crystallization process of a model inorganic salt (K2SO4) in an aqueous microdroplet (10-100 μm) in the presence of monolayers of monoelaidin (ME), monovaccenin (MV), monoolein (MO), and monolinolein (ML) assembled at a water-decanol interface. In particular, control monolayers of each monoglyceride at the water-oil interface did not accelerate nucleation (i.e., act as a template) of the crystallization of K2SO4. However, in the presence of 1-10 mM exogenous anions, certain types of monoglycerides did induce nucleation. The influence of the anions was consistent with the Hofmeister series. Monoglyceride monolayers in combination with chaotropic anions, such as SCN(-), imparted a euhedral crystal habit with a relatively lower C(onset), while kosmotropic anions showed less notable changes in the crystallization characteristics. However, this specific anion effect was seen only for monolayers of ME, MV, and MO but not for ML. This enhancement of nucleation-inducing ability upon addition of chaotropic anions appears to be related to the degree of chain splay: the larger the chain splay, the less anion efficiency in enhancing the templating capability. Our findings indicate that the improved nucleation-enhancing capabilities may originate from mutual interactions between anions and the monolayer, allowing the monoglyceride monolayers to adapt to a modulated self-assembled structure resulting in the greatest degree of control over K2SO4 crystallization.
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Affiliation(s)
- Omoakhe Tisor
- Department of Chemistry, Iona College , 715 North Avenue, New Rochelle, New York 10801, United States
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42
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Schwierz N, Horinek D, Netz RR. Specific ion binding to carboxylic surface groups and the pH dependence of the Hofmeister series. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:215-225. [PMID: 25494656 DOI: 10.1021/la503813d] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ion binding to acidic groups is a central mechanism for ion-specificity of macromolecules and surfaces. Depending on pH, acidic groups are either protonated or deprotonated and thus change not only charge but also chemical structure with crucial implications for their interaction with ions. In a two-step modeling approach, we first determine single-ion surface interaction potentials for a few selected halide and alkali ions at uncharged carboxyl (COOH) and charged carboxylate (COO(-)) surface groups from atomistic MD simulations with explicit water. Care is taken to subtract the bare Coulomb contribution due to the net charge of the carboxylate group and thereby to extract the nonelectrostatic ion-surface potential. Even at this stage, pronounced ion-specific effects are observed and the ion surface affinity strongly depends on whether the carboxyl group is protonated or not. In the second step, the ion surface interaction potentials are used in a Poisson-Boltzmann model to calculate the surface charge and the potential distribution in the solution depending on salt type, salt concentration, and solution pH in a self-consistent manner. Hofmeister phase diagrams are derived on the basis of the long-ranged forces between two carboxyl-functionalized surfaces. For cations we predict direct, reversed, and altered Hofmeister series as a function of the pH, qualitatively similar to recent experimental results for silica surfaces. The Hofmeister series reversal for cations is rationalized by a reversal of the single-cation affinity to the carboxyl group depending on its protonation state: the deprotonated carboxylate (COO(-)) surface group interacts most favorably with small cations such as Li(+) and Na(+), whereas the protonated carboxyl (COOH) surface group interacts most favorably with large cations such as Cs(+) and thus acts similarly to a hydrophobic surface group. Our results provide a general mechanism for the pH-dependent reversal of the Hofmeister series due to the different specific ion binding to protonated and deprotonated surface groups.
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Affiliation(s)
- Nadine Schwierz
- Chemistry Department, University of California , Berkeley, California 94720, United States
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43
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Pokorna S, Jurkiewicz P, Vazdar M, Cwiklik L, Jungwirth P, Hof M. Does fluoride disrupt hydrogen bond network in cationic lipid bilayer? Time-dependent fluorescence shift of Laurdan and molecular dynamics simulations. J Chem Phys 2014; 141:22D516. [DOI: 10.1063/1.4898798] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Sarka Pokorna
- J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic v.v.i., Dolejskova 3, 18223 Prague 8, Czech Republic
| | - Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic v.v.i., Dolejskova 3, 18223 Prague 8, Czech Republic
| | - Mario Vazdar
- Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute, P.O.B. 180, HR-10002 Zagreb, Croatia
| | - Lukasz Cwiklik
- J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic v.v.i., Dolejskova 3, 18223 Prague 8, Czech Republic
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
- Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic v.v.i., Dolejskova 3, 18223 Prague 8, Czech Republic
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Ionic strength and composition govern the elasticity of biological membranes. A study of model DMPC bilayers by force- and transmission IR spectroscopy. Chem Phys Lipids 2014; 186:17-29. [PMID: 25447291 DOI: 10.1016/j.chemphyslip.2014.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 11/05/2014] [Accepted: 11/11/2014] [Indexed: 12/15/2022]
Abstract
Infrared (IR) spectroscopy was used to quantify the ion mixture effect of seawater (SW), particularly the contribution of Mg(2+) and Ca(2+) as dominant divalent cations, on the thermotropic phase behaviour of 1,2-dimyristoyl-sn-glycero-3-posphocholine (DMPC) bilayers. The changed character of the main transition at 24 °C from sharp to gradual in films and the 1 °C shift of the main transition temperature in dispersions reflect the interactions of lipid headgroups with the ions in SW. Force spectroscopy was used to quantify the nanomechanical hardness of a DMPC supported lipid bilayer (SLB). Considering the electrostatic and ion binding equilibrium contributions while systematically probing the SLB in various salt solutions, we showed that ionic strength had a decisive influence on its nanomechanics. The mechanical hardness of DMPC SLBs in the liquid crystalline phase linearly increases with the increasing fraction of all ion-bound lipids in a series of monovalent salt solutions. It also linearly increases in the gel phase but almost three times faster (the corresponding slopes are 4.9 nN/100 mM and 13.32 nN/100 mM, respectively). We also showed that in the presence of divalent ions (Ca(2+) and Mg(2+)) the bilayer mechanical hardness was unproportionally increased, and that was accompanied with the decrease of Na(+) ion and increase of Cl(-) ion bound lipids. The underlying process is a cooperative and competitive ion binding in both the gel and the liquid crystalline phase. Bilayer hardness thus turned out to be very sensitive to ionic strength as well as to ionic composition of the surrounding medium. In particular, the indicated correlation helped us to emphasize the colligative properties of SW as a naturally occurring complex ion mixture.
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45
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Jing B, Abot RCT, Zhu Y. Semihydrophobic Nanoparticle-Induced Disruption of Supported Lipid Bilayers: Specific Ion Effect. J Phys Chem B 2014; 118:13175-82. [DOI: 10.1021/jp5074945] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Benxin Jing
- Department of Chemical and
Biomolecular Engineering, University of Notre Dame, 182 Fitzpatrick
Hall, Notre
Dame, Indiana 46556, United States
| | - Rosary C. T. Abot
- Department of Chemical and
Biomolecular Engineering, University of Notre Dame, 182 Fitzpatrick
Hall, Notre
Dame, Indiana 46556, United States
| | - Yingxi Zhu
- Department of Chemical and
Biomolecular Engineering, University of Notre Dame, 182 Fitzpatrick
Hall, Notre
Dame, Indiana 46556, United States
- Department of Chemistry and
Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States
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46
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Lidón López M, Queralt-Martín M, Alcaraz A. Experimental demonstration of charge inversion in a protein channel in the presence of monovalent cations. Electrochem commun 2014. [DOI: 10.1016/j.elecom.2014.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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47
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Przybyło M, Drabik D, Łukawski M, Langner M. Effect of Monovalent Anions on Water Transmembrane Transport. J Phys Chem B 2014; 118:11470-9. [DOI: 10.1021/jp505687d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Magda Przybyło
- Laboratory for Biophysics of Macromolecular Aggregates,
Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Pl. Grunwaldzki 13, 50-370 Wroclaw, Poland
| | - Dominik Drabik
- Laboratory for Biophysics of Macromolecular Aggregates,
Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Pl. Grunwaldzki 13, 50-370 Wroclaw, Poland
| | - Maciej Łukawski
- Laboratory for Biophysics of Macromolecular Aggregates,
Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Pl. Grunwaldzki 13, 50-370 Wroclaw, Poland
| | - Marek Langner
- Laboratory for Biophysics of Macromolecular Aggregates,
Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Pl. Grunwaldzki 13, 50-370 Wroclaw, Poland
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48
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Direct observation of electrogenic NH4(+) transport in ammonium transport (Amt) proteins. Proc Natl Acad Sci U S A 2014; 111:9995-10000. [PMID: 24958855 DOI: 10.1073/pnas.1406409111] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Ammonium transport (Amt) proteins form a ubiquitous family of integral membrane proteins that specifically shuttle ammonium across membranes. In prokaryotes, archaea, and plants, Amts are used as environmental NH4(+) scavengers for uptake and assimilation of nitrogen. In the eukaryotic homologs, the Rhesus proteins, NH4(+)/NH3 transport is used instead in acid-base and pH homeostasis in kidney or NH4(+)/NH3 (and eventually CO2) detoxification in erythrocytes. Crystal structures and variant proteins are available, but the inherent challenges associated with the unambiguous identification of substrate and monitoring of transport events severely inhibit further progress in the field. Here we report a reliable in vitro assay that allows us to quantify the electrogenic capacity of Amt proteins. Using solid-supported membrane (SSM)-based electrophysiology, we have investigated the three Amt orthologs from the euryarchaeon Archaeoglobus fulgidus. Af-Amt1 and Af-Amt3 are electrogenic and transport the ammonium and methylammonium cation with high specificity. Transport is pH-dependent, with a steep decline at pH values of ∼5.0. Despite significant sequence homologies, functional differences between the three proteins became apparent. SSM electrophysiology provides a long-sought-after functional assay for the ubiquitous ammonium transporters.
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49
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Khvostichenko DS, Ng JJD, Perry SL, Menon M, Kenis PJA. Effects of detergent β-octylglucoside and phosphate salt solutions on phase behavior of monoolein mesophases. Biophys J 2014; 105:1848-59. [PMID: 24138861 DOI: 10.1016/j.bpj.2013.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 08/16/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022] Open
Abstract
Using small-angle x-ray scattering (SAXS), we investigated the phase behavior of mesophases of monoolein (MO) mixed with additives commonly used for the crystallization of membrane proteins from lipidic mesophases. In particular, we examined the effect of sodium and potassium phosphate salts and the detergent β-octylglucoside (βOG) over a wide range of compositions relevant for the crystallization of membrane proteins in lipidic mesophases. We studied two types of systems: 1), ternary mixtures of MO with salt solutions above the hydration boundary; and 2), quaternary mixtures of MO with βOG and salt solutions over a wide range of hydration conditions. All quaternary mixtures showed highly regular lyotropic phase behavior with the same sequence of phases (Lα, Ia3d, and Pn3m) as MO/water mixtures at similar temperatures. The effects of additives in quaternary systems agreed qualitatively with those found in ternary mixtures in which only one additive is present. However, quantitative differences in the effects of additives on the lattice parameters of fully hydrated mesophases were found between ternary and quaternary mixtures. We discuss the implications of these findings for mechanistic investigations of membrane protein crystallization in lipidic mesophases and for studies of the suitability of precipitants for mesophase-based crystallization methods.
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Affiliation(s)
- Daria S Khvostichenko
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois
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50
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van der Post ST, Hunger J, Bonn M, Bakker HJ. Observation of Water Separated Ion-Pairs between Cations and Phospholipid Headgroups. J Phys Chem B 2014; 118:4397-403. [DOI: 10.1021/jp411458z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
| | - Johannes Hunger
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mischa Bonn
- Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Huib J. Bakker
- FOM Institute AMOLF, Science
Park 104, Amsterdam, The Netherlands
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