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International Journal of Molecular... Sep 2023Several discoveries show that with age and cataract formation, β-crystallin binds with the lens membrane or associates with other lens proteins, which bind with the...
Several discoveries show that with age and cataract formation, β-crystallin binds with the lens membrane or associates with other lens proteins, which bind with the fiber cell plasma membrane, accompanied by light scattering and cataract formation. However, how lipids (phospholipids and sphingolipids) and cholesterol (Chol) influence β-crystallin binding to the membrane is unclear. This research aims to elucidate the role of lipids and Chol in the binding of β-crystallin to the membrane and the membrane's physical properties (mobility, order, and hydrophobicity) with β-crystallin binding. We used electron paramagnetic resonance (EPR) spin-labeling methods to investigate the binding of β-crystallin with a model of porcine lens-lipid (MPLL), model of mouse lens-lipid (MMLL), and model of human lens-lipid (MHLL) membrane with and without Chol. Our results show that β-crystallin binds with all of the investigated membranes in a saturation manner, and the maximum parentage of the membrane surface occupied (MMSO) by β-crystallin and the binding affinity (K) of β-crystallin to the membranes followed trends: MMSO (MPLL) > MMSO (MMLL) > MMSO (MHLL) and K (MHLL) > K (MMLL) ≈ K (MPLL), respectively, in which the presence of Chol reduces the MMSO and K for all membranes. The mobility near the headgroup regions of the membranes decreases with an increase in the binding of β-crystallin; however, the decrease is more pronounced in the MPLL and MMLL membranes than the MHLL membrane. In the MPLL and MMLL membranes, the membranes become slightly ordered near the headgroup with an increase in β-crystallin binding compared to the MHLL membrane. The hydrophobicity near the headgroup region of the membrane increases with β-crystallin binding; however, the increase is more pronounced in the MPLL and MMLL membranes than the MHLL membrane, indicating that β-crystallin binding creates a hydrophobic barrier for the passage of polar molecules, which supports the barrier hypothesis in cataract formation. However, in the presence of Chol, there is no significant increase in hydrophobicity with β-crystallin binding, suggesting that Chol prevents the formation of a hydrophobic barrier, possibly protecting against cataract formation.
Topics: Mice; Humans; Animals; Swine; Crystallins; Lens, Crystalline; beta-Crystallins; Cataract; Phospholipids
PubMed: 37686406
DOI: 10.3390/ijms241713600 -
Frontiers in Endocrinology 2020A huge diversification of phospholipids, forming the aqueous interfaces of all biomembranes, cannot be accommodated within a simple concept of their role as membrane... (Review)
Review
A huge diversification of phospholipids, forming the aqueous interfaces of all biomembranes, cannot be accommodated within a simple concept of their role as membrane building blocks. Indeed, a number of signaling functions of (phospho)lipid molecules has been discovered. Among these signaling lipids, a particular group of oxygenated polyunsaturated fatty acids (PUFA), so called lipid mediators, has been thoroughly investigated over several decades. This group includes oxygenated octadecanoids, eicosanoids, and docosanoids and includes several hundreds of individual species. Oxygenation of PUFA can occur when they are esterified into major classes of phospholipids. Initially, these events have been associated with non-specific oxidative injury of biomembranes. An alternative concept is that these post-synthetically oxidatively modified phospholipids and their adducts with proteins are a part of a redox epiphospholipidome that represents a rich and versatile language for intra- and inter-cellular communications. The redox epiphospholipidome may include hundreds of thousands of individual molecular species acting as meaningful biological signals. This review describes the signaling role of oxygenated phospholipids in programs of regulated cell death. Although phospholipid peroxidation has been associated with almost all known cell death programs, we chose to discuss enzymatic pathways activated during apoptosis and ferroptosis and leading to peroxidation of two phospholipid classes, cardiolipins (CLs) and phosphatidylethanolamines (PEs). This is based on the available LC-MS identification and quantitative information on the respective peroxidation products of CLs and PEs. We focused on molecular mechanisms through which two proteins, a mitochondrial hemoprotein cytochrome (cyt ), and non-heme Fe lipoxygenase (LOX), change their catalytic properties to fulfill new functions of generating oxygenated CL and PE species. Given the high selectivity and specificity of CL and PE peroxidation we argue that enzymatic reactions catalyzed by cyt /CL complexes and 15-lipoxygenase/phosphatidylethanolamine binding protein 1 (15LOX/PEBP1) complexes dominate, at least during the initiation stage of peroxidation, in apoptosis and ferroptosis. We contrast cell-autonomous nature of CLox signaling in apoptosis correlating with its anti-inflammatory functions non-cell-autonomous ferroptotic signaling facilitating pro-inflammatory (necro-inflammatory) responses. Finally, we propose that small molecule mechanism-based regulators of enzymatic phospholipid peroxidation may lead to highly specific anti-apoptotic and anti-ferroptotic therapeutic modalities.
Topics: Animals; Apoptosis; Catalysis; Cell Death; Fatty Acids, Unsaturated; Ferroptosis; Humans; Lipidomics; Oxidation-Reduction; Phospholipids; Signal Transduction
PubMed: 33679610
DOI: 10.3389/fendo.2020.628079 -
Biomolecules Apr 2018Cellular membranes are composed of thousands of different lipids usually maintained within a narrow range of concentrations. In addition to their well-known structural... (Review)
Review
Cellular membranes are composed of thousands of different lipids usually maintained within a narrow range of concentrations. In addition to their well-known structural and metabolic roles, signaling functions for many lipids have also emerged over the last two decades. The latter largely depend on the ability of particular classes of lipids to interact specifically with a great variety of proteins and to regulate their localization and activity. Among these lipids, phosphatidic acid (PA) plays a unique role in a large repertoire of cellular activities, most likely in relation to its unique biophysical properties. However, until recently, only incomplete information was available to model the interaction between PA and its protein partners. The development of new liposome-based assays as well as molecular dynamic simulation are now providing novel information. We will review the different factors that have shown to modulate the capacity of PA to interact with specific domains in target proteins.
Topics: Animals; Cell Membrane; Humans; Phosphatidic Acids; Phospholipase D; Protein Binding; Static Electricity
PubMed: 29690573
DOI: 10.3390/biom8020020 -
Biochimica Et Biophysica Acta.... Apr 2017It was first discovered in 1992 that P-glycoprotein (Pgp, ABCB1), an ATP binding cassette (ABC) transporter, can transport phospholipids such as phosphatidylcholine,... (Review)
Review
It was first discovered in 1992 that P-glycoprotein (Pgp, ABCB1), an ATP binding cassette (ABC) transporter, can transport phospholipids such as phosphatidylcholine, -ethanolamine and -serine as well as glucosylceramide and glycosphingolipids. Subsequently, many other ABC transporters were identified to act as lipid transporters. For substrate transport by ABC transporters, typically a classic, alternating access model with an ATP-dependent conformational switch between a high and a low affinity substrate binding site is evoked. Transport of small hydrophilic substrates can easily be imagined this way, as the molecule can in principle enter and exit the transporter in the same orientation. Lipids on the other hand need to undergo a 180° degree turn as they translocate from one membrane leaflet to the other. Lipids and lipidated molecules are highly diverse, so there may be various ways how to achieve their flipping and flopping. Nonetheless, an increase in biophysical, biochemical and structural data is beginning to shed some light on specific aspects of lipid transport by ABC transporters. In addition, there is now abundant evidence that lipids affect ABC transporter conformation, dynamics as well as transport and ATPase activity in general. In this review, we will discuss different ways in which lipids and ABC transporters interact and how lipid translocation may be achieved with a focus on the techniques used to investigate these processes. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
Topics: ATP Binding Cassette Transporter, Subfamily B; Binding Sites; Biological Transport; Fatty Acids; Gene Expression; Humans; Models, Molecular; Phosphatidylcholines; Phosphatidylethanolamines; Phosphatidylserines; Protein Binding; Protein Isoforms; Substrate Specificity
PubMed: 27693344
DOI: 10.1016/j.bbamem.2016.09.023 -
ACS Applied Bio Materials Dec 2023Delivering cargo to the cell membranes of specific cell types in the body is a major challenge for a range of treatments, including immunotherapy. This study...
Delivering cargo to the cell membranes of specific cell types in the body is a major challenge for a range of treatments, including immunotherapy. This study investigates employing protein-decorated microbubbles (MBs) and ultrasound (US) to "tag" cellular membranes of interest with a specific protein. Phospholipid-coated MBs were produced and functionalized with a model protein using a metallochelating complex through an NTA(Ni) and histidine residue interaction. Successful "tagging" of the cellular membrane was observed using microscopy in adherent cells and was promoted by US exposure. Further modification of the MB surface to enable selective binding to target cells was then achieved by functionalizing the MBs with a targeting protein (transferrin) that specifically binds to a receptor on the target cell membrane. Attachment and subsequent transfer of material from MBs functionalized with transferrin to the target cells significantly increased, even in the absence of US. This work demonstrates the potential of these MBs as a platform for the noninvasive delivery of proteins to the surface of specific cell types.
Topics: Microbubbles; Ultrasonography; Cell Membrane; Phospholipids; Transferrins
PubMed: 38048163
DOI: 10.1021/acsabm.3c00861 -
Biochimica Et Biophysica Acta.... Feb 2018Heat shock protein 90 (Hsp90) is an essential molecular chaperone with versatile functions in cell homeostatic control under both normal and stress conditions. Hsp90 has...
Heat shock protein 90 (Hsp90) is an essential molecular chaperone with versatile functions in cell homeostatic control under both normal and stress conditions. Hsp90 has been found to be expressed on the cell surface, but the mechanism of Hsp90 association to the membrane remains obscure. In this study, the direct interaction of Hsp90 and phospholipid vesicles was characterized, and the role of Hsp90 on membrane physical state was explored. Using surface plasmon resonance (SPR), we observed a strong interaction between Hsp90 and different compositions of lipid. Hsp90 had a preference to bind with more unsaturated phospholipid species and the affinity was higher with negatively charged lipids than zwitterionic lipids. Increasing the mole fraction of cholesterol in the phospholipid led to a decrease of binding affinity to Hsp90. Circular dichroism (CD) spectroscopy of Hsp90 in PC membranes showed more α-helix structure than in aqueous buffer. The differential scanning calorimeter (DSC) and fluorescence polarization results showed Hsp90 could affect the transition temperature and fluidity of the bilayer. We postulate from these results that the association between Hsp90 and membranes may involve both electrostatic and hydrophobic force, and constitute a possible mechanism that modulates membrane lipid order during thermal fluctuations.
Topics: Animals; Binding, Competitive; Calorimetry, Differential Scanning; Cholesterol; Circular Dichroism; Ducks; Fluorescence Polarization; HSP90 Heat-Shock Proteins; Lipid Bilayers; Membrane Fluidity; Membrane Lipids; Phosphatidylcholines; Phospholipids; Protein Binding; Protein Structure, Secondary; Surface Plasmon Resonance; Transition Temperature
PubMed: 29166573
DOI: 10.1016/j.bbamem.2017.11.011 -
International Journal of Molecular... Mar 2021The interactions at the atomic level between small molecules and the main components of cellular plasma membranes are crucial for elucidating the mechanisms allowing for...
The interactions at the atomic level between small molecules and the main components of cellular plasma membranes are crucial for elucidating the mechanisms allowing for the entrance of such small species inside the cell. We have performed molecular dynamics and metadynamics simulations of tryptophan, serotonin, and melatonin at the interface of zwitterionic phospholipid bilayers. In this work, we will review recent computer simulation developments and report microscopic properties, such as the area per lipid and thickness of the membranes, atomic radial distribution functions, angular orientations, and free energy landscapes of small molecule binding to the membrane. Cholesterol affects the behaviour of the small molecules, which are mainly buried in the interfacial regions. We have observed a competition between the binding of small molecules to phospholipids and cholesterol through lipidic hydrogen-bonds. Free energy barriers that are associated to translational and orientational changes of melatonin have been found to be between 10-20 kJ/mol for distances of 1 nm between melatonin and the center of the membrane. Corresponding barriers for tryptophan and serotonin that are obtained from reversible work methods are of the order of 10 kJ/mol and reveal strong hydrogen bonding between such species and specific phospholipid sites. The diffusion of tryptophan and melatonin is of the order of 10-7 cm2/s for the cholesterol-free and cholesterol-rich setups.
Topics: 1,2-Dipalmitoylphosphatidylcholine; Cholesterol; Dimyristoylphosphatidylcholine; Hydrogen Bonding; Lipid Bilayers; Melatonin; Molecular Dynamics Simulation; Serotonin; Solutions; Static Electricity; Thermodynamics; Tryptophan; Water
PubMed: 33799606
DOI: 10.3390/ijms22062842 -
The Journal of Biological Chemistry Aug 2020TMEM16 Ca-activated phospholipid scramblases (CaPLSases) mediate rapid transmembrane phospholipid flip-flop and as such play essential roles in various physiological and...
TMEM16 Ca-activated phospholipid scramblases (CaPLSases) mediate rapid transmembrane phospholipid flip-flop and as such play essential roles in various physiological and pathological processes such as blood coagulation, skeletal development, viral infection, cell-cell fusion, and ataxia. Pharmacological tools specifically targeting TMEM16 CaPLSases are urgently needed to understand these novel membrane transporters and their contributions to health and disease. Tannic acid (TA) and epigallocatechin gallate (EGCG) were recently reported as promising TMEM16F CaPLSase inhibitors. However, our present study shows that TA and EGCG do not inhibit the phospholipid-scrambling or ion conduction activities of the dual-functional TMEM16F. Instead, we found that TA and EGCG mainly acted as fluorescence quenchers that rapidly suppress the fluorophores conjugated to annexin V, a phosphatidylserine-binding probe commonly used to report on TMEM16 CaPLSase activity. These data demonstrate the false positive effects of TA and EGCG on inhibiting TMEM16F phospholipid scrambling and discourage the use of these polyphenols as CaPLSase inhibitors. Appropriate controls as well as a combination of both fluorescence imaging and electrophysiological validation are necessary in future endeavors to develop TMEM16 CaPLSase inhibitors.
Topics: Animals; Anoctamins; Catechin; Enzyme Inhibitors; HEK293 Cells; Humans; Mice; Phospholipid Transfer Proteins; Phospholipids; Polyphenols; Tannins
PubMed: 32709749
DOI: 10.1074/jbc.AC120.014872 -
Biochimica Et Biophysica Acta.... Jun 2020Ole e 7 allergen from Olea europaea pollen possesses a major clinical relevance because it produces severe symptoms, such as anaphylaxis, in allergic patients exposed to...
Ole e 7 allergen from Olea europaea pollen possesses a major clinical relevance because it produces severe symptoms, such as anaphylaxis, in allergic patients exposed to high olive pollen counts. Ole e 7 is a non-specific lipid transfer protein (nsLTP) characterized by the presence of a tunnel-like hydrophobic cavity, which may be suitable for hosting and, thus, transporting lipids -as it has been described for other nsLTPs-. The identification of the primary amino acid sequence of Ole e 7, and its production as a recombinant allergen, allowed characterizing its lipid-binding properties and its effect at air-liquid interfaces. Fluorescence and interferometry experiments were performed using different phospholipid molecular species and free fatty acids to analyse the lipid-binding ability and specificity of the allergen. Molecular modelling of the allergen was used to determine the potential regions involved in lipid interaction. Changes in Ole e 7 structure after lipid interaction were analysed by circular dichroism. Changes in the IgE binding upon ligand interaction were determined by ELISA. Wilhelmy balance measurements and fluorescence surfactant adsorption tests were performed to analyse the surface activity of the allergen. Using these different approaches, we have demonstrated the ability of Ole e 7 to interact and bind to a wide range of lipids, especially negatively charged phospholipids and oleic acid. We have also identified the protein structural regions and the residues potentially involved in that interaction, suggesting how lipid-protein interactions could define the behaviour of the allergen once inhaled at the airways.
Topics: Immunoglobulin E; Lipid Metabolism; Models, Molecular; Molecular Structure; Olea; Oleic Acid; Phospholipids; Plant Proteins; Protein Binding
PubMed: 32142819
DOI: 10.1016/j.bbamem.2020.183258 -
The Journal of Physical Chemistry. B Jul 2019In this study, we provide a quantitative description of the adsorption of water-soluble -substituted glycine oligomers (peptoids) to supported lipid bilayers that mimic...
In this study, we provide a quantitative description of the adsorption of water-soluble -substituted glycine oligomers (peptoids) to supported lipid bilayers that mimic mammalian plasma membranes. We prepared a small array of systematically varied peptoid sequences ranging in length from 3 to 15 residues. Using the nonlinear optical method second harmonic generation (SHG), we directly monitored adsorption of aqueous solutions of 3- and 15-residue peptoids to phospholipid membranes of varying physical phase, cholesterol content, and head group charge in physiologically relevant pH buffer conditions without the use of extrinsic labels. Equilibrium binding constants and relative surface coverages of adsorbed peptoids were determined from fits to the Langmuir model. Three- and 15-residue peptoids did not interact with cholesterol-containing lipids or charged lipids in the same manner, suggesting that a peptoid's adsorption mechanism changes with sequence length. In a comparison of four three-residue peptoids, we observed a correlation between equilibrium binding constants and calculated log values. Cationic charge modulated surface coverage. Principles governing how peptoid sequence and membrane composition alter peptoid-lipid interactions may be extended to predict physiological effects of peptoids used as therapeutics or as coatings in medical devices.
Topics: Binding Sites; Hydrogen-Ion Concentration; Molecular Structure; Peptoids; Phospholipids; Solubility; Water
PubMed: 31251622
DOI: 10.1021/acs.jpcb.9b04641