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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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Bahreman A, Rabe M, Kros A, Bruylants G, Bonnet S. Binding of a ruthenium complex to a thioether ligand embedded in a negatively charged lipid bilayer: a two-step mechanism. Chemistry 2014; 20:7429-38. [PMID: 24782232 DOI: 10.1002/chem.201400377] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Indexed: 01/14/2023]
Abstract
The interaction between the ruthenium polypyridyl complex [Ru(terpy)(dcbpy)(H2O)](2+) (terpy = 2,2';6',2"-terpyridine, dcbpy = 6,6'-dichloro-2,2'-bipyridine) and phospholipid membranes containing either thioether ligands or cholesterol were investigated using UV-visible spectroscopy, Langmuir-Blodgett monolayer surface pressure measurements, and isothermal titration calorimety (ITC). When embedded in a membrane, the thioether ligand coordinated to the dicationic metal complex only when the phospholipids of the membrane were negatively charged, that is, in the presence of attractive electrostatic interaction. In such a case coordination is much faster than in homogeneous conditions. A two-step model for the coordination of the metal complex to the membrane-embedded sulfur ligand is proposed, in which adsorption of the complex to the negative surface of the monolayers or bilayers occurs within minutes, whereas formation of the coordination bond between the surface-bound metal complex and ligand takes hours. Finally, adsorption of the aqua complex to the membrane is driven by entropy. It does not involve insertion of the metal complex into the hydrophobic lipid layer, but rather simple electrostatic adsorption at the water-bilayer interface.
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Affiliation(s)
- Azadeh Bahreman
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, Leiden, 2300 RA (The Netherlands)
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Alley SH, Ces O, Barahona M, Templer RH. X-ray diffraction measurement of the monolayer spontaneous curvature of dioleoylphosphatidylglycerol. Chem Phys Lipids 2008; 154:64-7. [PMID: 18405663 DOI: 10.1016/j.chemphyslip.2008.03.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 03/05/2008] [Accepted: 03/12/2008] [Indexed: 11/17/2022]
Abstract
Phosphatidylglycerol (PG) is an anionic lipid commonly found in large proportions in the cell membranes of bacteria and plants and, to a lesser extent, in animal cells. PG plays an important role in the regulation and determination of the elastic properties of the membrane. Using small angle X-ray scattering experiments, we obtain that the monolayer spontaneous curvature of dioleoylphosphatidylglycerol (DOPG) is -1/150+/-0.021 nm(-1) when measured in 150 mM NaCl. When the experiments are carried out in 150 mM NaCl and 20mM MgCl(2), the value obtained for the monolayer spontaneous curvature is -1/8.7+/-0.037 nm(-1). These values are of importance in modelling the effects of curvature elastic stress in membrane lipid homeostasis in the bacterium Acholeplasma laidlawii [Alley, S.H., Barahona, M., Ces, O., Templer, R.H., in press. Biophysical regulation of lipid biosynthesis in the plasma membrane. Biophys. J.] and indicate that divalent cations can play a significant role in altering curvature elastic stress.
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Affiliation(s)
- Stephen H Alley
- Department of Bioengineering, Imperial College London, United Kingdom
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Pedersen UR, Leidy C, Westh P, Peters GH. The effect of calcium on the properties of charged phospholipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:573-82. [PMID: 16730642 DOI: 10.1016/j.bbamem.2006.03.035] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Revised: 03/08/2006] [Accepted: 03/14/2006] [Indexed: 11/28/2022]
Abstract
We have performed molecular dynamics simulations to investigate the structure and dynamics of charged bilayers as well as the distribution of counterions at the bilayer interface. For this, we have considered the negatively charged di-myristoyl-phosphatidyl-glycerol (DMPG) and di-myristoyl-phosphatidyl-serine (DMPS) bilayers as well as a protonated di-myristoyl-phosphatidyl-serine (DMPSH) bilayer. We were particularly interested in calcium ions due to their important role in biological systems. Simulations performed in the presence of calcium ions (DMPG, DMPS) or sodium ions (DMPS) were run for 45-60 ns. Simulation results for DMPG are compared with fluorescence measurements. The average areas per molecule were 47.4+/-0.5 A2 (DMPG with calcium), 47.3+/-0.5 A2 (DMPS with calcium), 51.3+/-1.0 A2 (DMPS with sodium) and 45.3+/-0.5 A2 (DMPSH). The structure of the negatively charged lipids is significantly affected by the counterions, where calcium ions have a more pronounced effect than sodium ions. Calcium ions were found to be tightly bound to the anionic groups of the lipid molecules and as such appear to constitute an integral part of the membrane interface on nanoseconds time scales. In contrast to sodium ions, calcium ions are localised in a narrow (approximately 10 A) band around the phosphate group. The interaction of calcium with the lipid molecules enhances the molecular packing of the PG and PS lipids. This observation is in good agreement with emission spectra of the membrane partitioning probe Laurdan in DMPG multilamellar vesicles that indicate an increase in the ordering of the DMPG bilayer due to the presence of calcium. Our results indicate that calcium ions, which often function as a second messengers in living cells have a pronounced effect on membrane structures, which may have implications during signal transduction events.
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Affiliation(s)
- Ulf R Pedersen
- Department of Life Science and Chemistry, Roskilde University, MEMPHYS-Center for Biomembrane Physics, 1 Universitetsvej, DK-4000 Roskilde, Denmark
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Wu F, Yang Z, Su X, Gong Y, Kuang T. Molecular reorganization induced by Ca2+ of plant photosystem I reconstituted into phosphatidylglycerol liposomes. Chem Phys Lipids 2005; 136:73-82. [PMID: 15936008 DOI: 10.1016/j.chemphyslip.2005.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 04/04/2005] [Accepted: 04/25/2005] [Indexed: 11/30/2022]
Abstract
The interaction of divalent cations with biomembranes is important for a number of biological processes. In this study, the regulatory effect of Ca2+ on the interaction between plant spinach photosystem I (PSI) particles and negatively charged lipid phosphatidylglycerol (PG) was investigated by circular dichroism (CD) spectroscopy. It was found that in the absence of CaCl2, PG causes an increase in alpha-helix and a decrease in disordered conformations of protein secondary structures of PSI, the beta-sheet and turns being almost unaffected. Meanwhile, the same effect also enhances the excitonic interactions relating to Chl a and Chl b from the PSI core complex and external antenna light-harvesting complex (LHCI). By contrast, in the presence of CaCl2, PG hardly interferes with the structure of the proteins' skeleton of PSI, but it can depress the excitonic interactions for Chl b of LHCI and for PSI core complex Chl a at (-) 433.5 nm of the CD signal which is accompanied by a blue shift of its peak. It is most likely that the neutralization of the phosphate groups in the PSI-PG complex and the negative surface charges of PSI, and partial dehydration in the vicinity of the ester CO region of the PG polar head group by the Ca-ions modify the interaction between PSI and PG, thereby inducing molecular reorganization of protein and pigments within both the external antenna LHCI and PSI core complex in proteoliposomes.
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Affiliation(s)
- Feng Wu
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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Yang Z, Su X, Wu F, Gong Y, Kuang T. Photochemical activities of plant photosystem I particles reconstituted into phosphatidylglycerol liposomes. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2005; 78:125-34. [PMID: 15664499 DOI: 10.1016/j.jphotobiol.2004.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Revised: 10/24/2004] [Accepted: 10/24/2004] [Indexed: 11/26/2022]
Abstract
Phosphatidylglycerol (PG) is the only anionic phospholipid in photosynthetic membrane and the important component of photosystem I (PSI). In this study, the interaction of PG with PSI particle from spinach was investigated by using reconstitution method. The results from the properties of electron transport, fluorescence emission, turbidity, and protein secondary structures in PSI complex incorporated into PG liposomes revealed the existence of PSI-PG interactions. A stimulation and an inhibition of oxygen uptake in PSI particle at a low and higher PG/chlorophyll mass ratio, respectively, were observed. Moreover, an additional enhancement and depression of electron flow in the PSI-PG complexes were occurred in the reaction medium containing CaCl2 at concentrations below and above 5 mM, the aggregation threshold of the reconstituted membranes, respectively. The results demonstrated that the maintenance of the structural optimization was needed for a stimulation of electron transport at a low PG/PSI mass ratio, while a decay of this PSI activity at high PG/PSI ratio was the result of inhibition of the energy transfer from LHCI to PSI reaction center induced by the dissociation of LHCI-680.
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Affiliation(s)
- Zhenle Yang
- Key Laboratory of Photosynthesis and Environmental, Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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Garidel P, Blume A, Hübner W. A Fourier transform infrared spectroscopic study of the interaction of alkaline earth cations with the negatively charged phospholipid 1, 2-dimyristoyl-sn-glycero-3-phosphoglycerol. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1466:245-59. [PMID: 10825446 DOI: 10.1016/s0005-2736(00)00166-8] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The interaction of aqueous phospholipid dispersions of negatively charged 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol, sodium salt (DMPG) with the divalent cations Mg(2+), Ca(2+) and Sr(2+) at equimolar ratios in 100 mM NaCl at pH 7 was investigated by Fourier transform infrared spectroscopy. The binding of the three cations induces a crystalline-like gel phase with highly ordered and rigid all-trans acyl chains. These features are observed after storage below room temperature for 24 h. When the gel phase is heated after prolonged incubation at low temperature phase transitions into the liquid crystalline phase are observed at 58 degrees C for the DMPG:Sr(2+), 65 degrees C for the DMPG:Mg(2+), and 80 degrees C for the DMPG:Ca(2+) complex. By subsequent cooling from temperatures above T(m) these complexes retain the features of a liquid crystalline phase with disordered acyl chains until a metastable gel phase is formed at temperatures between 38 and 32 degrees C. This phase is characterized by predominantly all-trans acyl chains, arranged in a loosely packed hexagonal or distorted hexagonal subcell lattice. Reheating the DMPG:Sr(2+) samples after a storage time of 2 h at 4 degrees C results in the transition of the metastable gel to the liquid crystalline phase at 35 degrees C. This phase transition into the liquid crystalline state at 35 degrees C is also observed for the Mg(2+) complex. However, for DMPG:Mg(2+) at higher temperatures, a partial recrystallization of the acyl chains occurs and the high temperature phase transition at 65 degrees C is also detected. In contrast, DMPG:Ca(2+) exhibits only the phase transition at 80 degrees C from the crystalline gel into the fluid state upon reheating. Below 20 degrees C, the rate of conversion from the metastable gel to a thermodynamically stable, crystalline-like gel phase decreases in the order Ca(2+)&z. Gt;Mg(2+)>Sr(2+). This conversion into the crystalline gel phase is accompanied by a complete dehydration of the phosphate groups in DMPG:Mg(2+) and by a reorientation of the polar lipid head groups in DMPG:Ca(2+) and in DMPG:Sr(2+). The primary binding sites of the cations are the PO(2)(-) groups of the phosphodiester moiety. Our infrared spectroscopic results suggest a deep penetration of the divalent cations into the polar head group region of DMPG bilayers, whereby the ester carbonyl groups, located in the interfacial region of the bilayers, are indirectly affected by strong hydrogen bonding of immobilized water molecules. In the liquid crystalline phase, the interaction of all three cations with DMPG is weak, but still observable in the infrared spectra of the DMPG:Ca(2+) complex by a slight ordering effect induced in the acyl chains, when compared to pure DMPG liposomes.
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Affiliation(s)
- P Garidel
- Martin-Luther-University Halle-Wittenberg, Institute of Physical Chemistry, Muehlpforte 1, D-06108, Halle/Saale, Germany
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Ségui JA, Maire V, Gabashvili IS, Fragata M. Oxygen evolution loss and structural transitions in photosystem II induced by low intensity UV-B radiation of 280 nm wavelength. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2000; 56:39-47. [PMID: 11073314 DOI: 10.1016/s1011-1344(00)00057-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
UV-B radiation of 280 nm wavelength (UV280) and low intensity (2.0 W/m2) gives rise to an important oxygen evolution (OE) loss in photosystem II (PSII) particles isolated from the thylakoid membrane of plant chloroplasts on the one hand, and to structural changes, or transitions, in the proteins of the PSII complex on the other hand. The latter UV280 effect was studied in this work by Fourier transform infrared (FT-IR) spectroscopy. First, irradiation of the PSII particles with UV280 for about 40 min causes an almost complete loss of OE activity. The remaining OE after 15, 20, 30 and 40 min is respectively 52, 44, 27 and 12% of the OE activity in control PSH particles kept in darkness. Secondly, difference FT-IR spectra of PSII particles irradiated for 30 min, i.e., [PSII irradiated with UV280]-minus-[PSII non-irradiated], show that the UV280 light is at the origin of significant IR absorbance changes in several spectral regions: (i) amide I (1696-1620 cm(-1)) and amide II (1580-1520 cm(-1)), (ii) tyrosine side chain (1620-1580 cm(-1) and 1520-1500 cm(-1), i.e., the v8a, v8b and v19a vibrational modes, respectively), and (iii) chlorophylls (1750-1696 cm(-1)). Thirdly, comparison of the UV-B effect reported here with structural changes induced by heat-stress in PSII proteins [M. Joshi, M. Fragata, Z. Naturforsch. 54c (1999) 35-43] clearly indicates that the stability of the functional centers in the PSII complex is dependent on a dynamic equilibrium between a-helix conformers and extended chain (beta-strand) structures. In this framework, transient 'alpha-helix-to-beta-strand transitions' are susceptible of giving rise in vivo to recurrent changes in the activity of the PSII complex, and as such act as a control mechanism of the photosynthetic function in the thylakoid membrane.
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Affiliation(s)
- J A Ségui
- Université du Québec à Trois-Rivières, Département de Chimie et Biologie, Trois-Rivieres, Canada
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Affiliation(s)
- Marianne L. McKelvy
- Analytical Sciences Laboratory, The Dow Chemical Company, U.S.A., Midland, Michigan 48667, and Applied Extrusion Technologies, 15 Reads Way, Newcastle, Delaware 19720
| | - Thomas R. Britt
- Analytical Sciences Laboratory, The Dow Chemical Company, U.S.A., Midland, Michigan 48667, and Applied Extrusion Technologies, 15 Reads Way, Newcastle, Delaware 19720
| | - Bradley L. Davis
- Analytical Sciences Laboratory, The Dow Chemical Company, U.S.A., Midland, Michigan 48667, and Applied Extrusion Technologies, 15 Reads Way, Newcastle, Delaware 19720
| | - J. Kevin Gillie
- Analytical Sciences Laboratory, The Dow Chemical Company, U.S.A., Midland, Michigan 48667, and Applied Extrusion Technologies, 15 Reads Way, Newcastle, Delaware 19720
| | - Felicia B. Graves
- Analytical Sciences Laboratory, The Dow Chemical Company, U.S.A., Midland, Michigan 48667, and Applied Extrusion Technologies, 15 Reads Way, Newcastle, Delaware 19720
| | - L. Alice Lentz
- Analytical Sciences Laboratory, The Dow Chemical Company, U.S.A., Midland, Michigan 48667, and Applied Extrusion Technologies, 15 Reads Way, Newcastle, Delaware 19720
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Interaction of photosystem II proteins with non-aggregated membranes constituted of phosphatidylglycerol and the electrically neutral phosphatidylcholine enhances the oxygen-evolving activity. Chem Phys Lipids 1998. [DOI: 10.1016/s0009-3084(97)00107-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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