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Kaushik D, Hitaishi P, Kumar A, Sen D, Kamil SM, Ghosh SK. Modulating a model membrane of sphingomyelin by a tricyclic antidepressant drug. Chem Phys Lipids 2024; 263:105419. [PMID: 38964567 DOI: 10.1016/j.chemphyslip.2024.105419] [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: 05/04/2024] [Revised: 06/15/2024] [Accepted: 06/28/2024] [Indexed: 07/06/2024]
Abstract
Tricyclic medicine such as amitriptyline (AMT) hydrochloride, initially developed to treat depression, is also used to treat neuropathic pain, anxiety disorder, and migraines. The mechanism of functioning of this type of drugs is ambiguous. Understanding the mechanism is important for designing new drug molecules with higher pharmacological efficiency. Hence, in the present study, biophysical approaches have been taken to shed light on their interactions with a model cellular membrane of brain sphingomyelin in the form of monolayer and multi-lamellar vesicles. The surface pressure-area isotherm infers the partitioning of a drug molecule into the lipid monolayer at the air water interface, providing a higher surface area per molecule and reducing the in-plane elasticity. Further, the surface electrostatic potential of the lipid monolayer is found to increase due to the insertion of drug molecule. The interfacial rheology revealed a reduction of the in-plane viscoelasticity of the lipid film, which, depends on the adsorption of the drug molecule onto the film. Small-angle X-ray scattering (SAXS) measurements on multilamellar vesicles (MLVs) have revealed that the AMT molecules partition into the hydrophobic core of the lipid membrane, modifying the organization of lipids in the membrane. The modified physical state of less rigid membrane and the transformed electrostatics of the membrane could influence its interaction with synaptic vesicles and neurotransmitters making higher availability of the neurotransmitters in the synaptic cleft.
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Affiliation(s)
- Devansh Kaushik
- Department of Physics, School of Natural Sciences, Shiv Nadar Institution of Eminence, NH 91, Tehsil Dadri, Uttar Pradesh 201214, India
| | - Prashant Hitaishi
- Department of Physics, School of Natural Sciences, Shiv Nadar Institution of Eminence, NH 91, Tehsil Dadri, Uttar Pradesh 201214, India
| | - Ashwani Kumar
- Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Debasis Sen
- Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Syed M Kamil
- Department of Physics, School of Natural Sciences, Shiv Nadar Institution of Eminence, NH 91, Tehsil Dadri, Uttar Pradesh 201214, India
| | - Sajal K Ghosh
- Department of Physics, School of Natural Sciences, Shiv Nadar Institution of Eminence, NH 91, Tehsil Dadri, Uttar Pradesh 201214, India.
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Gault S, Fonseca F, Cockell CS. Preservation of Bacillus subtilis' cellular liquid state at deep sub-zero temperatures in perchlorate brines. Commun Biol 2024; 7:588. [PMID: 38755264 PMCID: PMC11099114 DOI: 10.1038/s42003-024-06277-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 05/02/2024] [Indexed: 05/18/2024] Open
Abstract
Although a low temperature limit for life has not been established, it is thought that there exists a physical limit imposed by the onset of intracellular vitrification, typically occurring at ~-20 °C for unicellular organisms. Here, we show, through differential scanning calorimetry, that molar concentrations of magnesium perchlorate can depress the intracellular vitrification point of Bacillus subtilis cells to temperatures much lower than those previously reported. At 2.5 M Mg(ClO4)2, the peak vitrification temperature was lowered to -83 °C. Our results show that inorganic eutectic salts can in principle maintain liquid water in cells at much lower temperatures than those previously claimed as a lower limit to life, raising the prospects of active biochemical processes in low temperature natural settings. Our results may have implications for the habitability of Mars, where perchlorate salts are pervasive and potentially other terrestrial and extraterrestrial, cryosphere environments.
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Affiliation(s)
- Stewart Gault
- UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
| | - Fernanda Fonseca
- Université Paris-Saclay, INRAE, AgroParisTech, UMR SayFood, F-91120, Palaiseau, France
| | - Charles S Cockell
- UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
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Tortorella A, Oliva R, Giancola C, Petraccone L, Winter R. Bacterial model membranes under the harsh subsurface conditions of Mars. Phys Chem Chem Phys 2024; 26:760-769. [PMID: 37862004 DOI: 10.1039/d3cp03911k] [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: 10/21/2023]
Abstract
Biomembranes are a key component of all living systems. Most research on membranes is restricted to ambient physiological conditions. However, the influence of extreme conditions, such as the deep subsurface on Earth or extraterrestrial environments, is less well understood. The deep subsurface of Mars is thought to harbour high concentrations of chaotropic salts in brines, yet we know little about how these conditions would influence the habitability of such environments. Here, we investigated the combined effects of high concentrations of Mars-relevant salts, including sodium and magnesium perchlorate and sulphate, and high hydrostatic pressure on the stability, structure, and function of a bacterial model membrane. To this end, several biophysical techniques have been employed, including calorimetry, fluorescence and CD spectroscopy, confocal microscopy, and small-angle X-ray scattering. We demonstrate that sulphate and perchlorate salts affect the properties of the membrane differently, depending on the counterion present (Na+vs. Mg2+). We found that the perchlorates, which are believed to be abundant salts in the Martian environment, induce a more hydrated and less ordered membrane, strongly favouring the physiologically relevant fluid-like phase of the membrane even under high-pressure stress. Moreover, we show that the activity of the phospholipase A2 is strongly modulated by both high pressure and salt. Compellingly, in the presence of the chaotropic perchlorate, the enzymatic reaction proceeded at a reasonable rate even in the presence of condensing Mg2+ and at high pressure, suggesting that bacterial membranes could still persist when challenged to function in such a highly stressed Martian environment.
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Affiliation(s)
- Attila Tortorella
- Scuola Superiore Meridionale (SSM), Via Mezzocannone 4, 80138, Naples, Italy
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 26, 80126, Naples, Italy.
| | - Rosario Oliva
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 26, 80126, Naples, Italy.
| | - Concetta Giancola
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, 80131, Naples, Italy.
| | - Luigi Petraccone
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 26, 80126, Naples, Italy.
| | - Roland Winter
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, Otto-Hahn-Str. 4a, 44227, Dortmund, Germany.
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Bacalum M, Radu M, Osella S, Knippenberg S, Ameloot M. Generalized polarization and time-resolved fluorescence provide evidence for different populations of Laurdan in lipid vesicles. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2024; 250:112833. [PMID: 38141326 DOI: 10.1016/j.jphotobiol.2023.112833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/29/2023] [Accepted: 12/18/2023] [Indexed: 12/25/2023]
Abstract
The solvatochromic dye Laurdan is widely used in sensing the lipid packing of both model and biological membranes. The fluorescence emission maximum shifts from about 440 nm (blue channel) in condensed membranes (So) to about 490 nm (green channel) in the liquid-crystalline phase (Lα). Although the fluorescence intensity based generalized polarization (GP) is widely used to characterize lipid membranes, the fluorescence lifetime of Laurdan, in the blue and the green channel, is less used for that purpose. Here we explore the correlation between GP and fluorescence lifetimes by spectroscopic measurements on the So and Lα phases of large unilamellar vesicles of DMPC and DPPC. A positive correlation between GP and the lifetimes is observed in each of the optical channels for the two lipid phases. Microfluorimetric determinations on giant unilamellar vesicles of DPPC and DOPC at room temperature are performed under linearly polarized two-photon excitation to disentangle possible subpopulations of Laurdan at a scale below the optical resolution. Fluorescence intensities, GP and fluorescence lifetimes depend on the angle between the orientation of the linear polarization of the excitation light and the local normal to the membrane of the optical cross-section. This angular variation depends on the lipid phase and the emission channel. GP and fluorescence intensities in the blue and green channel in So and in the blue channel in Lα exhibit a minimum near 90o. Surprisingly, the intensity in the green channel in Lα reaches a maximum near 90o. The fluorescence lifetimes in the two optical channels also reach a pronounced minimum near 90o in So and Lα, apart from the lifetime in the blue channel in Lα where the lifetime is short with minimal angular variation. To our knowledge, these experimental observations are the first to demonstrate the existence of a bent conformation of Laurdan in lipid membranes, as previously suggested by molecular dynamics calculations.
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Affiliation(s)
- Mihaela Bacalum
- Department of Life and Environmental Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, Reactorului, 30, Măgurele 077125, Romania
| | - Mihai Radu
- Department of Life and Environmental Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, Reactorului, 30, Măgurele 077125, Romania
| | - Silvio Osella
- Chemical and Biological Systems Simulation Lab, Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland
| | - Stefan Knippenberg
- Biomedical Research Institute, Hasselt University, Agoralaan Bldg. C, 3590 Diepenbeek, Belgium; Theory Lab, Hasselt University, Agoralaan Bldg. D, 3590 Diepenbeek, Belgium
| | - Marcel Ameloot
- Biomedical Research Institute, Hasselt University, Agoralaan Bldg. C, 3590 Diepenbeek, Belgium.
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Knop JM, Mukherjee S, Jaworek MW, Kriegler S, Manisegaran M, Fetahaj Z, Ostermeier L, Oliva R, Gault S, Cockell CS, Winter R. Life in Multi-Extreme Environments: Brines, Osmotic and Hydrostatic Pressure─A Physicochemical View. Chem Rev 2023; 123:73-104. [PMID: 36260784 DOI: 10.1021/acs.chemrev.2c00491] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Elucidating the details of the formation, stability, interactions, and reactivity of biomolecular systems under extreme environmental conditions, including high salt concentrations in brines and high osmotic and high hydrostatic pressures, is of fundamental biological, astrobiological, and biotechnological importance. Bacteria and archaea are able to survive in the deep ocean or subsurface of Earth, where pressures of up to 1 kbar are reached. The deep subsurface of Mars may host high concentrations of ions in brines, such as perchlorates, but we know little about how these conditions and the resulting osmotic stress conditions would affect the habitability of such environments for cellular life. We discuss the combined effects of osmotic (salts, organic cosolvents) and hydrostatic pressures on the structure, stability, and reactivity of biomolecular systems, including membranes, proteins, and nucleic acids. To this end, a variety of biophysical techniques have been applied, including calorimetry, UV/vis, FTIR and fluorescence spectroscopy, and neutron and X-ray scattering, in conjunction with high pressure techniques. Knowledge of these effects is essential to our understanding of life exposed to such harsh conditions, and of the physical limits of life in general. Finally, we discuss strategies that not only help us understand the adaptive mechanisms of organisms that thrive in such harsh geological settings but could also have important ramifications in biotechnological and pharmaceutical applications.
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Affiliation(s)
- Jim-Marcel Knop
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Sanjib Mukherjee
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Michel W Jaworek
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Simon Kriegler
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Magiliny Manisegaran
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Zamira Fetahaj
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Lena Ostermeier
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Rosario Oliva
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany.,Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126Naples, Italy
| | - Stewart Gault
- UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, EH9 3FDEdinburgh, United Kingdom
| | - Charles S Cockell
- UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, EH9 3FDEdinburgh, United Kingdom
| | - Roland Winter
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
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Structural Responses of Nucleic Acids to Mars-Relevant Salts at Deep Subsurface Conditions. Life (Basel) 2022; 12:life12050677. [PMID: 35629344 PMCID: PMC9144689 DOI: 10.3390/life12050677] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 11/28/2022] Open
Abstract
High pressure deep subsurface environments of Mars may harbor high concentrations of dissolved salts, such as perchlorates, yet we know little about how these salts influence the conditions for life, particularly in combination with high hydrostatic pressure. We investigated the effects of high magnesium perchlorate concentrations compared to sodium and magnesium chloride salts and high pressure on the conformational dynamics and stability of double-stranded B-DNA and, as a representative of a non-canonical DNA structure, a DNA-hairpin (HP), whose structure is known to be rather pressure-sensitive. To this end, fluorescence spectroscopies including single-molecule FRET methodology were applied. Our results show that the stability both of the B-DNA as well as the DNA-HP is largely preserved at high pressures and high salt concentrations, including the presence of chaotropic perchlorates. The perchlorate anion has a small destabilizing effect compared to chloride, however. These results show that high pressures at the kbar level and perchlorate anions can modify the stability of nucleic acids, but that they do not represent a barrier to the gross stability of such molecules in conditions associated with the deep subsurface of Mars.
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Somkuti J, Molnár OR, Grád A, Smeller L. Pressure Perturbation Studies of Noncanonical Viral Nucleic Acid Structures. BIOLOGY 2021; 10:1173. [PMID: 34827166 PMCID: PMC8615049 DOI: 10.3390/biology10111173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/08/2021] [Accepted: 11/08/2021] [Indexed: 12/16/2022]
Abstract
G-quadruplexes are noncanonical structures formed by guanine-rich sequences of the genome. They are found in crucial loci of the human genome, they take part in the regulation of important processes like cell proliferation and cell death. Much less is known about the subjects of this work, the viral G-quadruplexes. We have chosen three potentially G-quadruplex-forming sequences of hepatitis B. We measured the stability and the thermodynamic parameters of these quadruplexes. We also investigated the potential stabilization of these G-quadruplexes by binding a special ligand that was originally developed for cancer therapy. Fluorescence and infrared spectroscopic measurements were performed over wide temperature and pressure ranges. Our experiments indicate the small unfolding volume change of all three oligos. We found a difference between the unfolding of the 2-quartet and the 3-quartet G-quadruplexes. All three G-quadruplexes were stabilized by TMPyP4, which is a cationic porphyrin developed for stabilizing the human telomere.
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Affiliation(s)
| | | | | | - László Smeller
- Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Budapest, Hungary; (J.S.); (O.R.M.); (A.G.)
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Jahmidi-Azizi N, Gault S, Cockell CS, Oliva R, Winter R. Ions in the Deep Subsurface of Earth, Mars, and Icy Moons: Their Effects in Combination with Temperature and Pressure on tRNA-Ligand Binding. Int J Mol Sci 2021; 22:ijms221910861. [PMID: 34639202 PMCID: PMC8509373 DOI: 10.3390/ijms221910861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/03/2021] [Accepted: 10/06/2021] [Indexed: 01/12/2023] Open
Abstract
The interactions of ligands with nucleic acids are central to numerous reactions in the biological cell. How such reactions are affected by harsh environmental conditions such as low temperatures, high pressures, and high concentrations of destructive ions is still largely unknown. To elucidate the ions’ role in shaping habitability in extraterrestrial environments and the deep subsurface of Earth with respect to fundamental biochemical processes, we investigated the effect of selected salts (MgCl2, MgSO4, and Mg(ClO4)2) and high hydrostatic pressure (relevant for the subsurface of that planet) on the complex formation between tRNA and the ligand ThT. The results show that Mg2+ salts reduce the binding tendency of ThT to tRNA. This effect is largely due to the interaction of ThT with the salt anions, which leads to a strong decrease in the activity of the ligand. However, at mM concentrations, binding is still favored. The ions alter the thermodynamics of binding, rendering complex formation that is more entropy driven. Remarkably, the pressure favors ligand binding regardless of the type of salt. Although the binding constant is reduced, the harsh conditions in the subsurface of Earth, Mars, and icy moons do not necessarily preclude nucleic acid–ligand interactions of the type studied here.
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Affiliation(s)
- Nisrine Jahmidi-Azizi
- Physical Chemistry I-Biophysical Chemistry, Department of Chemistry and Chemical Biology, TU Dortmund University, 44227 Dortmund, Germany;
| | - Stewart Gault
- UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Edinburgh EH9 3FD, UK; (S.G.); (C.S.C.)
| | - Charles S. Cockell
- UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Edinburgh EH9 3FD, UK; (S.G.); (C.S.C.)
| | - Rosario Oliva
- Physical Chemistry I-Biophysical Chemistry, Department of Chemistry and Chemical Biology, TU Dortmund University, 44227 Dortmund, Germany;
- Correspondence: (R.O.); (R.W.)
| | - Roland Winter
- Physical Chemistry I-Biophysical Chemistry, Department of Chemistry and Chemical Biology, TU Dortmund University, 44227 Dortmund, Germany;
- Correspondence: (R.O.); (R.W.)
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