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Dennison SR, Morton LH, Badiani K, Harris F, Phoenix DA. Bacterial susceptibility and resistance to modelin-5. SOFT MATTER 2023; 19:8247-8263. [PMID: 37869970 DOI: 10.1039/d3sm01007d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Modelin-5 (M5-NH2) killed Pseudomonas aeruginosa with a minimum lethal concentration (MLC) of 5.86 μM and strongly bound its cytoplasmic membrane (CM) with a Kd of 23.5 μM. The peptide adopted high levels of amphiphilic α-helical structure (75.0%) and penetrated the CM hydrophobic core (8.0 mN m-1). This insertion destabilised CM structure via increased lipid packing and decreased fluidity (ΔGmix < 0), which promoted high levels of lysis (84.1%) and P. aeruginosa cell death. M5-NH2 showed a very strong affinity (Kd = 3.5 μM) and very high levels of amphiphilic α-helical structure with cardiolipin membranes (96.0%,) which primarily drove the peptide's membranolytic action against P. aeruginosa. In contrast, M5-NH2 killed Staphylococcus aureus with an MLC of 147.6 μM and weakly bound its CM with a Kd of 117.6 μM, The peptide adopted low levels of amphiphilic α-helical structure (35.0%) and only penetrated the upper regions of the CM (3.3 mN m-1). This insertion stabilised CM structure via decreased lipid packing and increased fluidity (ΔGmix > 0) and promoted only low levels of lysis (24.3%). The insertion and lysis of the S. aureus CM by M5-NH2 showed a strong negative correlation with its lysyl phosphatidylglycerol (Lys-PG) content (R2 > 0.98). In combination, these data suggested that Lys-PG mediated mechanisms inhibited the membranolytic action of M5-NH2 against S. aureus, thereby rendering the organism resistant to the peptide. These results are discussed in relation to structure/function relationships of M5-NH2 and CM lipids that underpin bacterial susceptibility and resistance to the peptide.
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Affiliation(s)
- Sarah R Dennison
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, UK.
| | - Leslie Hg Morton
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, UK.
| | - Kamal Badiani
- Pepceuticals Limited, 4 Feldspar Close, Warrens Park, Enderby, Leicestershire, LE19 4JS, UK
| | - Frederick Harris
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, UK.
| | - David A Phoenix
- Office of the Vice Chancellor, London South Bank University, 103 Borough Road, London SE1 0AA, UK
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2
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Yamaguchi T, Hirakawa R, Ochiai H. Correlation between sphingomyelin and the membrane stability of mammalian erythrocytes. Comp Biochem Physiol B Biochem Mol Biol 2023; 265:110833. [PMID: 36738823 DOI: 10.1016/j.cbpb.2023.110833] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/29/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023]
Abstract
Lipid compositions of mammalian erythrocyte membranes are different among species. Therefore, the information on hemolysis from mammalian erythrocytes is useful to understand membrane properties of human erythrocytes. In this work, pressure-induced hemolysis and hypotonic one were examined using erythrocytes of human, sheep, cow, cat, dog, pig, horse, rat, and mouse. Pressure-induced hemolysis was suppressed by membrane sphingomyelin, whereas hypotonic hemolysis decreased upon increment of cell diameter. Mass spectra of erythrocyte membrane lipids demonstrated that sphingomyelin with an acyl chain 24:1 was associated with the suppression of pressure-induced hemolysis. In cow erythrocytes, pressure-induced hemolysis was greatly suppressed and the detachment of cytoskeletal proteins from the membrane under hypotonic conditions was also inhibited. Taken together, these results suggest that sphingomyelin with 24:1 fatty acid plays an important role in the stability of the erythrocyte membrane, perhaps via cholesterol.
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Affiliation(s)
- Takeo Yamaguchi
- Department of Chemistry, Faculty of Science, Fukuoka University, Nanakuma 8-19-1, Jonan-ku, Fukuoka 814-0180, Japan.
| | - Ruka Hirakawa
- Department of Chemistry, Faculty of Science, Fukuoka University, Nanakuma 8-19-1, Jonan-ku, Fukuoka 814-0180, Japan
| | - Hideharu Ochiai
- Research Institute of Bioscience, School of Veterinary Medicine, Azabu University, Sagamihara, Kanagawa 252-5201, Japan
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3
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Kanagasingam S, von Ruhland C, Welbury R, Singhrao SK. Antimicrobial, Polarizing Light, and Paired Helical Filament Properties of Fragmented Tau Peptides of Selected Putative Gingipains. J Alzheimers Dis 2022; 89:1279-1291. [PMID: 36031895 DOI: 10.3233/jad-220486] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Tau is an established substrate for gingipains secreted by Porphyromonas gingivalis. Hyperphosphorylation of tau and neurofibrillary tangle (NFT) formation is a defining lesion of Alzheimer's disease (AD) where NFT distribution is related to Braak stage and disease severity. OBJECTIVE To assess gingipains'-fragmented tau peptides for their antimicrobial properties and for the likelihood of paired helical/straight filament (PHF/SF) formation with implications for the NFT lesion. METHODS Seven non-phosphorylated (A-G) and three phosphorylated (A-C) tau peptides, were tested for antimicrobial properties against P. gingivalis. Polarizing light properties were determined using Congo Red staining. Secondary and tertiary structures of peptides B-F were determined using transmission electron microscopy (TEM) and circular dichroism (CD) was undertaken for the soluble peptides A in phosphorylated and non-phosphorylated states. RESULTS Phosphorylated tau peptide A displayed a significant effect against planktonic P. gingivalis. The CD results demonstrated that both peptides A, in phosphorylated and non-phosphorylated states, in aqueous solution, adopted mainly β-type structures. Non-phosphorylated peptides B-F and phosphorylated peptides B-C were insoluble and fibrillar under the TEM. The secondary and tertiary structures of the non-phosphorylated peptide B demonstrated fewer helical twists, whereas peptide C displayed significantly more helical twists along the whole fiber(s) length following its phosphorylation. CONCLUSION Phosphorylated peptide A reduced P. gingivalis viability. CD spectroscopy demonstrated the phosphorylated and the non-phosphorylated peptide A predominantly formed from β-sheet structures in aqueous solution with potential antimicrobial activity. Phosphorylation of tau peptides physically changed their tertiary structure into PHFs with potential for self-aggregation and binding to the NFT lesion.
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Affiliation(s)
- Shalini Kanagasingam
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | - Christopher von Ruhland
- Electron and Light Microscopy Facility, College of Biomedical and Life Sciences, Cardiff University, Wales, UK
| | - Richard Welbury
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | - Sim K Singhrao
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
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4
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Carboxyl group-modified myoglobin shows membrane-permeabilizing activity. Arch Biochem Biophys 2022; 728:109371. [DOI: 10.1016/j.abb.2022.109371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 06/16/2022] [Accepted: 07/21/2022] [Indexed: 01/05/2023]
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5
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Banerjee T, Sarkar N, Toner J, Basu A. Rolled Up or Crumpled: Phases of Asymmetric Tethered Membranes. PHYSICAL REVIEW LETTERS 2019; 122:218002. [PMID: 31283334 DOI: 10.1103/physrevlett.122.218002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Indexed: 06/09/2023]
Abstract
We show that inversion-asymmetric tethered membranes exhibit a new double-spiral phase with long range orientational order not present in symmetric membranes. We calculate the universal algebraic spiral shapes of these membranes in this phase. Asymmetry can trigger the crumpling of these membranes as well. In vitro experiments on lipid membranes, red blood cell membrane extracts, and on graphene coated on one side, could test these predictions.
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Affiliation(s)
- Tirthankar Banerjee
- LPTMS, UMR 8626, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay CEDEX, France
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700064, West Bengal, India
| | - Niladri Sarkar
- Max-Planck Institut für Physik Komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany
- Laboratoire Physico Chimie Curie, UMR 168, Institut Curie, PSL Research University, CNRS, Sorbonne Universitié, 75005 Paris, France
| | - John Toner
- Department of Physics and Institute of Theoretical Science, University of Oregon, Eugene, Oregon 97403, USA
| | - Abhik Basu
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700064, West Bengal, India
- Max-Planck Institut für Physik Komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany
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6
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Sarkar S, Bose D, Giri RP, Mukhopadhyay MK, Chakrabarti A. Effects of GM1 on brain spectrin-aminophospholipid interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:298-305. [PMID: 29920238 DOI: 10.1016/j.bbamem.2018.06.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 06/13/2018] [Accepted: 06/14/2018] [Indexed: 12/11/2022]
Abstract
Spectrin, a major component of the membrane skeletal meshwork of metazoan cells, is implicated to associate with membrane domains and is known to act as a scaffold for stabilization and activation of different signalling modules. We have studied the effect of GM1 (monosialotetrahexosyl ganglioside), a well-known model ganglioside and a signalling moiety, on the interaction of non-erythroid brain spectrin with both saturated and unsaturated aminophospholipids by spectroscopic methods. We observe that GM1 modulates brain spectrin-aminophospholipid interaction to the greatest degree whereas its effect on erythroid spectrin is not as pronounced. Fluorescence quenching studies show that brain spectrin interacts with DMPC/DMPE-based vesicles with a 10-fold increased affinity in presence of very low amounts of 2% and 5% GM1, and the extent of quenching decreases progressively in presence of increasing amounts of GM1. Interaction of brain spectrin with unsaturated membrane systems of DOPC/DOPE weakens in presence GM1. Increase in the mean lifetime of the Trp residues of brain spectrin in presence of GM1 indicates change in the microenvironment of spectrin, without affecting the secondary structure of the protein significantly. Studies on pressure - area isotherm of Langmuir-Blodgett monolayer and Brewster's angle microscopy show that GM1 has an expanding effect on the aminophospholipid monolayers, and ordered regions in DMPC/DMPE mixed monolayers are formed and are stabilized at higher pressure. GM1-induced fluidization of the phospholipid membranes and probable physical contact between bulky sugar head group of GM1 and spectrin, may explain the modulatory role of GM1 on aminophospholipid interactions with nonerythroid brain spectrin.
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Affiliation(s)
- Sauvik Sarkar
- Crystallography & Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064, India; Homi Bhabha National Institute, Mumbai 400094, India.
| | - Dipayan Bose
- Crystallography & Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064, India; Homi Bhabha National Institute, Mumbai 400094, India.
| | - Rajendra P Giri
- Homi Bhabha National Institute, Mumbai 400094, India; Surface Physics and Material Sciences Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064, India
| | - Mrinmay K Mukhopadhyay
- Homi Bhabha National Institute, Mumbai 400094, India; Surface Physics and Material Sciences Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064, India.
| | - Abhijit Chakrabarti
- Crystallography & Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064, India; Homi Bhabha National Institute, Mumbai 400094, India.
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7
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The Charge Properties of Phospholipid Nanodiscs. Biophys J 2017; 111:989-98. [PMID: 27602726 DOI: 10.1016/j.bpj.2016.06.041] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 03/22/2016] [Accepted: 06/15/2016] [Indexed: 11/23/2022] Open
Abstract
Phospholipids (PLs) are a major, diverse constituent of cell membranes. PL diversity arises from the nature of the fatty acid chains, as well as the headgroup structure. The headgroup charge is thought to contribute to both the strength and specificity of protein-membrane interactions. Because it has been difficult to measure membrane charge, ascertaining the role charge plays in these interactions has been challenging. Presented here are charge measurements on lipid Nanodiscs at 20°C in 100 mM NaCl, 50 mM Tris, at pH 7.4. Values are also reported for measurements made in the presence of Ca(2+) and Mg(2+) as a function of NaCl concentration, pH, and temperature, and in solvents containing other types of cations and anions. Measurements were made for neutral (phosphatidylcholine and phosphatidylethanolamine) and anionic (phosphatidylserine, phosphatidic acid, cardiolipin, and phosphatidylinositol 4,5-bisphosphate (PIP2)) PLs containing palmitoyl-oleoyl and dimyristoyl fatty acid chains. In addition, charge measurements were made on Nanodiscs containing an Escherichia coli lipid extract. The data collected reveal that 1) POPE is anionic and not neutral at pH 7.4; 2) high-anionic-content Nanodiscs exhibit polyelectrolyte behavior; 3) 3 mM Ca(2+) neutralizes a constant fraction of the charge, but not a constant amount of charge, for POPS and POPC Nanodiscs; 4) in contrast to some previous work, POPC only interacts weakly with Ca(2+); 5) divalent cations interact with lipids in a lipid- and ion-specific manner for POPA and PIP2 lipids; and 6) the monovalent anion type has little influence on the lipid charge. These results should help eliminate inconsistencies among data obtained using different techniques, membrane systems, and experimental conditions, and they provide foundational data for developing an accurate view of membranes and membrane-protein interactions.
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Exported Epoxide Hydrolases Modulate Erythrocyte Vasoactive Lipids during Plasmodium falciparum Infection. mBio 2016; 7:mBio.01538-16. [PMID: 27795395 PMCID: PMC5082902 DOI: 10.1128/mbio.01538-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Erythrocytes are reservoirs of important epoxide-containing lipid signaling molecules, including epoxyeicosatrienoic acids (EETs). EETs function as vasodilators and anti-inflammatory modulators in the bloodstream. Bioactive EETs are hydrolyzed to less active diols (dihydroxyeicosatrienoic acids) by epoxide hydrolases (EHs). The malaria parasite Plasmodium falciparum infects host red blood cells (RBCs) and exports hundreds of proteins into the RBC compartment. In this study, we show that two parasite epoxide hydrolases, P. falciparum epoxide hydrolases 1 (PfEH1) and 2 (PfEH2), both with noncanonical serine nucleophiles, are exported to the periphery of infected RBCs. PfEH1 and PfEH2 were successfully expressed in Escherichia coli, and they hydrolyzed physiologically relevant erythrocyte EETs. Mutations in active site residues of PfEH1 ablated the ability of the enzyme to hydrolyze an epoxide substrate. Overexpression of PfEH1 or PfEH2 in parasite-infected RBCs resulted in a significant alteration in the epoxide fatty acids stored in RBC phospholipids. We hypothesize that the parasite disruption of epoxide-containing signaling lipids leads to perturbed vascular function, creating favorable conditions for binding and sequestration of infected RBCs to the microvascular endothelium. The malaria parasite exports hundreds of proteins into the erythrocyte compartment. However, for most of these proteins, their physiological function is unknown. In this study, we investigate two “hypothetical” proteins of the α/β-hydrolase fold family that share sequence similarity with epoxide hydrolases (EHs)—enzymes that destroy bioactive epoxides. Altering EH expression in parasite-infected erythrocytes resulted in a significant change in the epoxide fatty acids stored in the host cell. We propose that these EH enzymes may help the parasite to manipulate host blood vessel opening and inflame the vessel walls as they pass through the circulation system. Understanding how the malaria parasite interacts with its host RBCs will aid in our ability to combat this deadly disease.
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9
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Fluorescence study of the effect of cholesterol on spectrin–aminophospholipid interactions. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:635-45. [DOI: 10.1007/s00249-015-1057-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Revised: 06/17/2015] [Accepted: 06/25/2015] [Indexed: 11/26/2022]
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10
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Spectrin and phospholipids - the current picture of their fascinating interplay. Cell Mol Biol Lett 2014; 19:158-79. [PMID: 24569979 PMCID: PMC6276000 DOI: 10.2478/s11658-014-0185-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 02/19/2014] [Indexed: 12/02/2022] Open
Abstract
The spectrin-based membrane skeleton is crucial for the mechanical stability and resilience of erythrocytes. It mainly contributes to membrane integrity, protein organization and trafficking. Two transmembrane protein macro-complexes that are linked together by spectrin tetramers play a crucial role in attaching the membrane skeleton to the cell membrane, but they are not exclusive. Considerable experimental data have shown that direct interactions between spectrin and membrane lipids are important for cell membrane cohesion. Spectrin is a multidomain, multifunctional protein with several distinctive structural regions, including lipid-binding sites within CH tandem domains, a PH domain, and triple helical segments, which are excellent examples of ligand specificity hidden in a regular repetitive structure, as recently shown for the ankyrin-sensitive lipid-binding domain of beta spectrin. In this review, we summarize the state of knowledge about interactions between spectrin and membrane lipids.
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11
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Thermodynamic interactions of a cis and trans benzanilide with Escherichia coli bacterial membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 41:687-93. [DOI: 10.1007/s00249-012-0835-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/15/2012] [Accepted: 06/22/2012] [Indexed: 10/28/2022]
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12
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Role of molecular architecture on the relative efficacy of aurein 2.5 and modelin 5. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2094-102. [PMID: 22617856 DOI: 10.1016/j.bbamem.2012.05.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 05/11/2012] [Accepted: 05/14/2012] [Indexed: 11/22/2022]
Abstract
In order to gain an insight into the mechanism of antimicrobial peptide action, aurein 2.5 and modelin-5 were studied. When tested against Staphylococcus aureus, aurein 2.5 showed approximately 5-fold greater efficacy even though the higher net positive charge and higher helix stability shown by modelin-5 would have predicated modelin-5 to be the more effective antimicrobial. However, in the presence of S. aureus membrane mimics, aurein 2.5 showed greater helical content (75% helical) relative to modelin-5 (51% helical) indicative of increase in membrane association. This was supported by monolayer data showing that aurein 2.5 (6.6mNm(-1)) generated greater pressure changes than modelin-5 (5.3mNm(-1)). Peptide monolayers indicted that modelin-5 formed a helix horizontal to the plane of an asymmetric interface which would be supported by the even distribution of charge and hydrophobicity along the helical long axis and facilitate lysis by non-specific membrane binding. In contrast, a groove structure observed on the surface of aurein 2.5 was predicted to be the cause of enhanced lipid binding (K(d)=75μM) relative to modelin-5 (K(d)=118μM) and the balance of hydrophobicity along the aurein 2.5 long axis supported deep penetration into the membrane in a tilt formation. This oblique orientation generates greater lytic efficacy in high anionic lipid (71%) compared to modelin-5 (32%).
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13
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Dennison SR, Phoenix DA. Effect of cholesterol on the membrane interaction of Modelin-5 isoforms. Biochemistry 2011; 50:10898-909. [PMID: 22082130 DOI: 10.1021/bi201267v] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modelin-5 isoforms were used to gain an insight into the effects of amidation on antimicrobial selectivity. When tested against Escherichia coli, amidation increased toxicity 10-fold (MIC = 31.25 μM) while showing limited increased hemolytic activity (2% lysis). Our results show that both the amidated and non-amidated peptides had a disordered structure in aqueous solution (<18% helical) and folded to form helices at the membrane interface (for example, >43% in the presence of DMPC). The stabilization of the helical structure by amidation has previously been shown to play a key role in increasing antibacterial efficacy. The presence of cholesterol in the membrane increases the packing density (C(s)(-1) values 25-33 mN m(-1)) and so prevents the peptide from forming stable association with the membrane, which is evidenced by the higher binding coefficient (K(d)) in the presence of cholesterol: 57.70 μM for Modelin-5-COOH and 35.64 μM for Modelin-5-CONH(2) compared to the presence of E. coli lipid extract (10 μM), which would prevent local concentration of the peptide at the bilayer interface as seen by reduction in monolayer interaction. This in turn would be predicted to inhibit activity.
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Affiliation(s)
- Sarah R Dennison
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, UK
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14
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Dennison SR, Phoenix DA. Influence of C-terminal amidation on the efficacy of modelin-5. Biochemistry 2011; 50:1514-23. [PMID: 21241054 DOI: 10.1021/bi101687t] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To gain insight into the effects of amidation on the mechanism of membrane interaction, we studied two peptides modelin-5-COOH and modelin-5-CONH(2) and found they exhibit high surface activities (23.2 and 27.1 mN/m, respectively). When they were tested against Escherichia coli, amidation was seen to increase efficacy approximately 10-fold. Our results demonstrated that both peptides adopted low levels of α-helix in solution (<20%); however, in the presence of E. coli lipid extract, modelin-5-CONH(2) had a greater propensity (69%) than modelin-5-COOH (32%) to generate α-helical structure. The binding coefficient for both peptides was ∼10 μM, and the Hill coefficient approximated 1, suggesting that for both peptides the interactions with E. coli membranes were monomeric and comparable in strength. The peptides showed a clear preference for anionic lipid, with monolayer data showing that enhanced levels of helicity were associated with a greater pressure change (∼6 mN/m). Use of fluorescein-phosphatidylethanolamine showed the amidated version was able to generate greater levels of membrane disruption, which was confirmed by thermodynamic analysis. The data would imply that both peptides are able to initially bind to bilayer structures, but upon binding, the amidation stabilizes helix formation. This would be expected to help overcome a key rate-limiting step and generate higher local concentrations of peptide at the bilayer interface, which in turn would be predicted to increase efficacy.
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Affiliation(s)
- Sarah R Dennison
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, U.K
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15
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Czogalla A, Grzymajło K, Jezierski A, Sikorski AF. Phospholipid-induced structural changes to an erythroid β spectrin ankyrin-dependent lipid-binding site. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2612-20. [DOI: 10.1016/j.bbamem.2008.07.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 07/01/2008] [Accepted: 07/18/2008] [Indexed: 12/01/2022]
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16
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Czogalla A, Jaszewski AR, Diakowski W, Bok E, Jezierski A, Sikorski AF. Structural insight into an ankyrin-sensitive lipid-binding site of erythroid beta-spectrin. Mol Membr Biol 2007; 24:215-24. [PMID: 17520478 DOI: 10.1080/09687860601102427] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
It was recently shown that the region within beta-spectrin responsible for interactions with ankyrin includes a lipid-binding site which displayed sensitivity to inhibition by ankyrin. We studied its structure by constructing a series of single and double spin-labeled beta-spectrin-derived peptides and analyzing their spin-spin distances via electron paramagnetic resonance spectroscopy and the Fourier deconvolution method. The results indicate that the whole ankyrin-sensitive lipid-binding site of beta-spectrin exhibits a helical conformation revealing a distinct 3(10)-helix contribution at its N-terminus. The start of the helix was located five residues upstream along the sequence compared to the theoretical predictions. A model based on the obtained data provides direct evidence that the examined lipid-binding site is a highly amphipathic helix, which is correlated with the specific conformation of its N-terminal fragment.
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Abstract
Spectrin is the major constituent protein of the erythrocyte cytoskeleton which forms a filamentous network on the cytoplasmic face of the membrane by providing a scaffold for a variety of proteins. In this review, several aspects of spectrin organization are highlighted, particularly with respect to its ability to bind hydrophobic ligands and its interaction with membrane surfaces. The characteristic binding of the fluorescent hydrophobic probes Prodan and pyrene to spectrin, which allows an estimation of the polarity of the hydrophobic probe binding site, is illustrated. In addition, the contribution of uniquely localized and conserved tryptophan residues in the 'spectrin repeats' in these processes is discussed. A functional implication of the presence of hydrophobic binding sites in spectrin is its recently discovered chaperone-like activity. Interestingly, spectrin exhibits residual structural integrity even after denaturation which could be considered as a hallmark of cytoskeletal proteins. Future research could provide useful information about the possible role played by spectrin in cellular physiology in healthy and diseased states.
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Affiliation(s)
- Abhijit Chakrabarti
- Biophysics Division, Saha Institute of Nuclear Physics, Kolkata 700 064, India.
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18
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Lipid composition of pea (Pisum sativum L.) and maize (Zea mays L.) root plasma membrane and membrane-bound peroxidase and superoxide dismutase. ARCH BIOL SCI 2007. [DOI: 10.2298/abs0704295k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Plasma membrane was isolated from roots of pea and maize plants and used to analyze POD and SOD isoforms, as well as lipid composition. Among lipids, phospholipids were the main lipid class, with phosphatidylcho?line being the most abundant individual component in both pea and maize plasma membranes. Significant differences between the two plant species were found in the contents of cerebrosides, free sterols, and steryl glycosides. Most maize POD isoforms were with neutral and anionic pI values, but the opposite was observed in pea. While both anionic and cationic SOD isoforms were isolated from maize, only two anionic SOD isoforms were detected in pea.
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Petelska AD, Figaszewski ZA. Interfacial tension of phosphatidylcholine–phosphatidylserine system in bilayer lipid membrane. Biophys Chem 2006; 120:199-206. [PMID: 16380205 DOI: 10.1016/j.bpc.2005.10.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 09/11/2005] [Accepted: 10/21/2005] [Indexed: 10/25/2022]
Abstract
The effect of pH of electrolyte solution on the interfacial tension of lipid membrane formed of phosphatidylcholine (PC, lecithin)-phosphatidylserine (PS) system was studied. In this article, three models describing the H+ and OH- ions adsorption in the bilayer lipid surface are presented. In Model I and Model II, the surface is continuous with uniformly distributed functional groups constituting the centres of H+ and OH- ions adsorption while in the other the surface is built of lipid molecules, free or with attached H+ and OH- ions. In these models contribution of the individual lipid molecule forms to interfacial tension of the bilayer were assumed to be additive. In Model III the adsorption of the H+ and OH- ions at the PC-PS bilayer surface was described in terms of the Gibbs isotherm. Theoretical equations are derived to describe this dependence in the whole pH range.
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Affiliation(s)
- Aneta D Petelska
- Institute of Chemistry, University of Bialystok, Al. J. Pilsudskiego 11/4, 15-443 Bialystok, Poland
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20
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Grzybek M, Chorzalska A, Bok E, Hryniewicz-Jankowska A, Czogalla A, Diakowski W, Sikorski AF. Spectrin-phospholipid interactions. Existence of multiple kinds of binding sites? Chem Phys Lipids 2006; 141:133-41. [PMID: 16566912 DOI: 10.1016/j.chemphyslip.2006.02.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Accepted: 02/20/2006] [Indexed: 11/28/2022]
Abstract
The object of this paper is to review briefly the studies on the interactions of erythroid and non-erythroid spectrins with lipids in model and natural membranes. An important progress on the identification of lipid-binding sites has recently been made although many questions remain still unanswered. In particular, our understanding of the physiological role of such interactions is still limited. Another important issue is the occurrence of spectrins in membrane rafts, how they are attached to the raft and what is their function in rafts.
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Affiliation(s)
- Michał Grzybek
- University of Wrocław, Institute of Biochemistry and Molecular Biology, Poland
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21
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Flaumenhaft R. Formation and fate of platelet microparticles. Blood Cells Mol Dis 2006; 36:182-7. [PMID: 16466949 DOI: 10.1016/j.bcmd.2005.12.019] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Accepted: 12/07/2005] [Indexed: 11/26/2022]
Abstract
There is increasing evidence that platelet microparticles participate in thrombus formation. Yet the origin of platelet microparticles and their fate in the circulation remain poorly defined. It is unknown, for example, whether circulating platelet microparticles found in healthy individuals are derived from activated platelets or generated during megakaryopoiesis. The life span of platelet microparticles and the mechanism of their clearance have also not been determined. This article addresses these fundamental aspects of the physiology of platelet microparticles.
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Affiliation(s)
- Robert Flaumenhaft
- Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center, 41 Ave Louis Pasteur, RE319, Boston, MA 02115, USA.
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22
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Diakowski W, Ozimek Ł, Bielska E, Bem S, Langner M, Sikorski AF. Cholesterol affects spectrin–phospholipid interactions in a manner different from changes resulting from alterations in membrane fluidity due to fatty acyl chain composition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:4-12. [PMID: 16464436 DOI: 10.1016/j.bbamem.2005.11.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 11/10/2005] [Accepted: 11/11/2005] [Indexed: 11/16/2022]
Abstract
We previously showed that erythrocyte and brain spectrins bind phospholipid vesicles and monolayers prepared from phosphatidylethanolamine and phosphatidylserine and their mixtures with phosphatidylcholine (Review: A.F. Sikorski, B. Hanus-Lorenz, A. Jezierski, A. R. Dluzewski, Interaction of membrane skeletal proteins with membrane lipid domain, Acta Biochim. Polon. 47 (2000) 565). Here, we show how changes in the fluidity of the phospholipid monolayer affect spectrin-phospholipid interaction. The presence of up to 10%-20% cholesterol in the PE/PC monolayer facilitates the penetration of the monolayer by both types of spectrin. For monolayers constructed from mixtures of PI/PC and cholesterol, the effect of spectrins was characterised by the presence of two maxima (at 5 and 30% cholesterol) of surface pressure for erythroid spectrin, and a single maximum (at 20% cholesterol) for brain spectrin. The binding assay results indicated a small but easily detectable decrease in the affinity of erythrocyte spectrin for FAT-liposomes prepared from a PE/PC mixture containing cholesterol, and a 2- to 5-fold increase in maximal binding capacity (B(max)) depending on the cholesterol content. On the other hand, the results from experiments with a monolayer constructed from homogenous synthetic phospholipids indicated an increase in deltapi change with the increase in the fatty acyl chain length of the phospholipids used to prepare the monolayer. This was confirmed by the results of a pelleting experiment. Adding spectrins into the subphase of raft-like monolayers constructed from DOPC, SM and cholesterol (1/1/1) induced an increase in surface pressure. The deltapi change values were, however, much smaller than those observed in the case of a natural PE/PC (6/4) monolayer. An increased binding capacity for spectrins of liposomes prepared from a "raft-like" mixture of lipids could also be concluded from the pelleting assay. In conclusion, we suggest that the effect of membrane lipid fluidity on spectrin-phospholipid interactions is not simple but depends on how it is regulated, i.e., by cholesterol content or by the chemical structure of the membrane lipids.
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Affiliation(s)
- Witold Diakowski
- Institute of Biochemistry and Molecular Biology, University of Wrocław, Przybyszewskiego 63/77, 51-148 Wrocław, Poland
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23
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Ciana A, Balduini C, Minetti G. Detergent-resistant membranes in human erythrocytes and their connection to the membrane-skeleton. J Biosci 2005; 30:317-28. [PMID: 16052070 DOI: 10.1007/bf02703669] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In cell membranes, local inhomogeneity in the lateral distribution of lipids and proteins is thought to exist in vivo in the form of lipid 'rafts', microdomains enriched in cholesterol and sphingolipids, and in specific classes of proteins, that appear to play specialized roles for signal transduction, cell-cell recognition, parasite or virus infection, and vesicular trafficking. These structures are operationally defined as membranes resistant to solubilization by nonionic detergents at 4 degree C (detergent-resistant membranes, DRMs). This definition appears to be necessary and sufficient, although additional manoeuvres, not always described with sufficient detail, may be needed to ensure isolation of DRMs, like mechanical homogenization, and changes in the pH and/or ionic strength of the solubilization medium. We show here for the human erythrocyte that the different conditions adopted may lead to the isolation of qualitatively and quantitatively different DRM fractions, thus contributing to the complexity of the notion itself of lipid raft. A significant portion of erythrocyte DRMs enriched in reported lipid raft markers, such as flotillin-1, flotillin-2 and GM1, is anchored to the spectrin membrane-skeleton via electrostatic interactions that can be disrupted by the simultaneous increase in pH and ionic strength of the solubilization medium.
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Affiliation(s)
- Annarita Ciana
- Università di Pavia, Dipartimento di Biochimica "A. Castellani", via Bassi, 21, 27100 Pavia, Italy
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24
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Hryniewicz-Jankowska A, Bok E, Dubielecka P, Chorzalska A, Diakowski W, Jezierski A, Lisowski M, Sikorski A. Mapping of an ankyrin-sensitive, phosphatidylethanolamine/phosphatidylcholine mono- and bi-layer binding site in erythroid beta-spectrin. Biochem J 2005; 382:677-85. [PMID: 15171729 PMCID: PMC1133825 DOI: 10.1042/bj20040358] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Revised: 05/13/2004] [Accepted: 06/02/2004] [Indexed: 11/17/2022]
Abstract
It has been shown previously that binding of vesicles and monolayers containing PE (phosphatidylethanolamine) by either erythroid or non-erythroid spectrin proved sensitive to inhibition by purified erythrocyte ankyrin. We tested the lipid-binding affinities of the purified ankyrin-binding domain of beta-spectrin and of its truncated mutants in four ways, by analysing: (1) penetration of 'loose' PE/PC (phosphatidylcholine) monolayers; (2) binding to liposomes in suspension; (3) competition with spectrin for liposomes; and (4) binding of a PE/PC monolayer in a surface plasmon resonance system. The results obtained indicated that the full-length ankyrin-binding domain bound PE/PC mono- and bi-layers with moderate affinity, penetrated monolayers and competed with spectrin for liposomes. Moreover, its truncated mutants that retained the N-terminal part, in contrast with those lacking eight or 38 N-terminal residues (which bound lipid mono- and bi-layers with lower affinity), bound PE/PC mono- and bi-layers with an affinity and capacity comparable with those of the full-length ankyrin-binding domain, and this activity was inhibited by purified erythrocyte ankyrin. The full-length domain, in contrast with the mutant lacking 38 N-terminal residues, induced a small increase in the fluidity of PE/PC membranes when probed with 5'-doxyl stearate, similar to the effect of purified spectrin. Therefore we conclude that the binding site for PE-rich lipids, which is sensitive to ankyrin inhibition, is located in a 38-residue N-terminal fragment of the beta-spectrin ankyrin-binding domain, and that the first eight residues play a key role in this activity.
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Affiliation(s)
- Anita Hryniewicz-Jankowska
- *Institute of Biochemistry and Molecular Biology, University of Wrocław, ul. Przybyszewskiego 63/77, 51–148 Wrocław, Poland
| | - Ewa Bok
- *Institute of Biochemistry and Molecular Biology, University of Wrocław, ul. Przybyszewskiego 63/77, 51–148 Wrocław, Poland
| | - Patrycja Dubielecka
- *Institute of Biochemistry and Molecular Biology, University of Wrocław, ul. Przybyszewskiego 63/77, 51–148 Wrocław, Poland
| | - Anna Chorzalska
- *Institute of Biochemistry and Molecular Biology, University of Wrocław, ul. Przybyszewskiego 63/77, 51–148 Wrocław, Poland
| | - Witold Diakowski
- *Institute of Biochemistry and Molecular Biology, University of Wrocław, ul. Przybyszewskiego 63/77, 51–148 Wrocław, Poland
| | - Adam Jezierski
- †Faculty of Chemistry, University of Wrocław, ul. I. Joliot-Curie 14, 50–383 Wrocław, Poland
| | - Marek Lisowski
- †Faculty of Chemistry, University of Wrocław, ul. I. Joliot-Curie 14, 50–383 Wrocław, Poland
| | - Aleksander F. Sikorski
- *Institute of Biochemistry and Molecular Biology, University of Wrocław, ul. Przybyszewskiego 63/77, 51–148 Wrocław, Poland
- To whom correspondence should be addressed (email )
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25
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An X, Guo X, Gratzer W, Mohandas N. Phospholipid binding by proteins of the spectrin family: a comparative study. Biochem Biophys Res Commun 2005; 327:794-800. [PMID: 15649416 DOI: 10.1016/j.bbrc.2004.12.063] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Indexed: 10/26/2022]
Abstract
Erythroid and neuronal spectrin (fodrin) are both known to interact strongly with the aminophospholipids that occur in the inner leaflet of plasma membranes. In erythroid spectrin the positions of the binding sites within the constituent (alphaI and betaI) polypeptide chains have been defined, and also the importance of the lipid interaction in regulating the properties of the membrane. Here we report the locations of the corresponding binding sites in the alphaII and betaII chains that make up the fodrin molecule. Of the 10 lipid-binding repeats in the erythroid spectrin chains 5 are conserved in fodrin; one cluster of 3 consecutive structural repeating units in alphaI erythroid spectrin (repeats 8-10) is displaced by one repeat in alphaII fodrin (repeats 9-11). Fodrin also contains one binding site at the N-terminus of the alphaII chain, not present in the erythroid protein. The regions of the two spectrins containing equivalent lipid-binding sites show a much higher degree of sequence identity than corresponding repeats that do not share this property. The evolutionary conservation of the distribution of a large proportion of strong lipid-binding sites in the polypeptide chains of these two proteins of disparate character argues for a specific function of fodrin-phospholipid interactions in the neuron.
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Affiliation(s)
- Xiuli An
- Red Cell Physiology Laboratory, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY 10021, USA.
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26
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Ray S, Chakrabarti A. Membrane interaction of erythroid spectrin: surface-density-dependent high-affinity binding to phosphatidylethanolamine. Mol Membr Biol 2004; 21:93-100. [PMID: 15204438 DOI: 10.1080/09687680310001625800] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Density-dependent spectrin binding to dimyristoylphosphatidylcholine/dimyristoylphosphatidylethanolamine (DMPC/DMPE) small uni-lamellar vesicles (SUVs) has been directly evaluated in this work from the increase in the extent of quenching of the tryptophan fluorescence of spectrin at two different temperatures, above and below the main phase transition temperatures (Tm). Results from the binding studies of spectrin to phospholipid SUVs indicated that the binding dissociation constant Kd, increased from 45 +/- 7 nM in pure DMPC SUVs to 219 +/- 20 nM in DMPC/DMPE (50:50) SUVs, both in the gel and liquid crystalline phase. However, in pure DMPE SUVs the Kd decreased drastically to 0.7 +/- 0.2 nM in the gel phase at 18 degrees C and to 2.6 +/- 0.7 nM in the fluid phase at 55 degrees C indicating a high affinity binding of spectrin for the bilayer-forming DMPE. The maximum extent of phospholipid-induced quenching and the number of spectrin molecules associated with one SUV particle, evaluated in the present work, led to a model in DMPC/DMPE bilayer membranes indicating the PE-binding site of spectrin to localize at one of the terminal domains of the dimeric spectrin. A direct evidence of the localization of the PE-binding site at one of the terminal ends of the spectrin dimer also came from electron microscopic observation in fluid membranes made of bovine brain PE.
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Affiliation(s)
- Sibnath Ray
- Biophysics Division, Saha Institute of Nuclear Physics, Kolkata, India
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27
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Fitchen N, O'Shea P, Williams P, Hardie KR. Electrostatic sensor for identifying interactions between peptides and bacterial membranes. Mol Immunol 2003; 40:407-11. [PMID: 14568386 DOI: 10.1016/s0161-5890(03)00153-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The use of the membrane probe fluorescein phosphatidylethanolamine (FPE) to investigate membrane binding is well established. However, until now, its use has been restricted to studies involving peptides and eukaryotic membranes. This useful tool has been developed to interrogate peptide:prokaryotic membrane interactions by introducing novel methodology to incorporate FPE into the membranes of UV killed, whole bacterial cells. The electrostatic potential of the membrane in the immediate vicinity of the probe affects the protonation state of the xanthene ring system in the fluorescein head group, which is held close to the membrane surface. When altered, e.g. by peptide binding and insertion, a change in fluorescence results, which can be measured spectrophotometrically. Applicability of this technique to bacterial surface interactions was confirmed by production of a binding curve for both a synthetic peptide and a 37kDa protein. Future investigations are anticipated to utilize this technology to characterize interactions of other toxins plus antimicrobial peptides such as lactoferricin and defensins with their target membranes.
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Affiliation(s)
- Nicola Fitchen
- Institute of Infection, Immunity, and Inflammation, University of Nottingham, Queen's Medical School, C-floor West block, Nottingham NG7 2UH, UK
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28
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Le Rumeur E, Fichou Y, Pottier S, Gaboriau F, Rondeau-Mouro C, Vincent M, Gallay J, Bondon A. Interaction of dystrophin rod domain with membrane phospholipids. Evidence of a close proximity between tryptophan residues and lipids. J Biol Chem 2003; 278:5993-6001. [PMID: 12480947 DOI: 10.1074/jbc.m207321200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dystrophin is assumed to act via the central rod domain as a flexible linker between the amino-terminal actin binding domain and carboxyl-terminal proteins associated with the membrane. The rod domain is made up of 24 spectrin-like repeats and has been shown to modify the physical properties of lipid membranes. The nature of this association still remains unclear. Tryptophan residues tend to cluster at or near to the water-lipid interface of the membrane. To assess dystrophin rod domain-membrane interactions, tryptophan residues properties of two recombinant proteins of the rod domain were examined by (1)H NMR and fluorescence techniques in the presence of membrane lipids. F114 (residues 439-553) is a partly folded protein as inferred from (1)H NMR, tryptophan fluorescence emission intensity, and the excited state lifetime. By contrast, F125 (residues 439-564) is a folded compact protein. Tryptophan fluorescence quenching shows that both proteins are characterized by structural fluctuations with their tryptophan residues only slightly buried from the surface. In the presence of negatively charged small vesicles, the fluorescence characteristics of F125 change dramatically, indicating that tryptophan residues are in a more hydrophobic environment. Interestingly, these modifications are not observed with F114. Fluorescence quenching experiments confirm that tryptophan residues are shielded from the solvent in the complex F125 lipids by a close contact with lipids. The use of membrane-bound quenchers allowed us to conclude that dystrophin rod domain lies along the membrane surface and may be involved in a structural array comprising membrane and cytoskeletal proteins as well as membrane lipids.
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Affiliation(s)
- Elisabeth Le Rumeur
- Laboratoire de Résonance Magnétique Nucléaire en Biologie et Médecine, Unité Propre de Recherche de l'Enseignement Supérieur EA 2230, Faculté de Médecine, CS 34317, Rennes 35043 cedex, France.
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29
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Abstract
Lipids in biological membranes are asymmetrically distributed across the bilayer; the amine-containing phospholipids are enriched on the cytoplasmic surface of the plasma membrane, while the choline-containing and sphingolipids are enriched on the outer surface. The maintenance of transbilayer lipid asymmetry is essential for normal membrane function, and disruption of this asymmetry is associated with cell activation or pathologic conditions. Lipid asymmetry is generated primarily by selective synthesis of lipids on one side of the membrane. Because passive lipid transbilayer diffusion is slow, a number of proteins have evolved to either dissipate or maintain this lipid gradient. These proteins fall into three classes: 1) cytofacially-directed, ATP-dependent transporters ("flippases"); 2) exofacially-directed, ATP-dependent transporters ("floppases"); and 3) bidirectional, ATP-independent transporters ("scramblases"). The flippase is highly selective for phosphatidylserine and functions to keep this lipid sequestered from the cell surface. Floppase activity has been associated with the ABC class of transmembrane transporters. Although they are primarily nonspecific, at least two members of this class display selectivity for their substrate lipid. Scramblases are inherently nonspecific and function to randomize the distribution of newly synthesized lipids in the endoplasmic reticulum or plasma membrane lipids in activated cells. It is the combined action of these proteins and the physical properties of the membrane bilayer that generate and maintain transbilayer lipid asymmetry.
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Affiliation(s)
- David L Daleke
- Medical Sciences Program, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Bloomington, IN 47405, USA.
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30
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Diakowski W, Sikorski A. Brain spectrin exerts much stronger effect on anionic phospholipid monolayers than erythroid spectrin. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1564:403-11. [PMID: 12175923 DOI: 10.1016/s0005-2736(02)00476-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Red blood cell spectrin and its nonerythroid analogues are linked to integral proteins of the membrane by several skeletal protein receptors, such as ankyrin and protein 4.1 together with p55. However, there are also many reasons for believing that they are insufficient to engender all the properties that characterise the native membrane. Therefore, we are concerned with the mechanism by which brain spectrin interacts with phospholipids of the membrane bilayer. Brain and erythrocyte spectrin were shown previously to bind phospholipid vesicles as well as monolayers prepared from aminophospholipids: phosphatidylethanolamine and phosphatidylserine and their mixtures with phosphatidylcholine (PC). In the present study, it is shown that brain spectrin binds to monolayers prepared from anionic phospholipids, such as phosphatidylinositol (PI), phosphatidic acid (PA), phosphatidyl glycerol, diphosphatidylglycerol, and their mixtures with PC. Brain spectrin injected into the subphase to reach nanomolar concentration induced a substantial increase in the surface pressure of monolayers prepared from the phospholipids and their mixtures mentioned above, possibly by penetrating them. This effect is stronger in the case of monolayers prepared from anionic phospholipids alone and weaker when monolayers were prepared from mixtures with PC. The weakest effect was observed in the case of phosphatidylinositol-4,5-bisphosphate monolayers. An interaction of brain spectrin with monolayers prepared from anionic phospholipids (PI/PC 7:3 and PA/PC 7:3) was inhibited (PI/PC much stronger than PA/PC) by purified erythrocyte ankyrin, which indicates that the binding site for those lipids is located in the beta-subunit, possibly in, or in close proximity of, the ankyrin-binding site. In contrast, erythrocyte spectrin injected into the subphase induced a change in the surface pressure of monolayers prepared from anionic phospholipids, which was equal or smaller than the value of surface pressure change induced by protein without a monolayer. This effect was different from what had been observed previously for monolayers prepared from aminophospholipids and their mixtures with PC, and from the data for nonerythroid spectrin presented here.
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Affiliation(s)
- Witold Diakowski
- Department of Genetic Biochemistry, Institute of Biochemistry and Molecular Biology, University of Wrocław, ul. Przybyszewskiego 63/77, 51-148, Wrocław, Poland
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31
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Affiliation(s)
- Peter J Quinn
- Division of Life Sciences, King's College London, 150 Stamford Street, London SE1 9NN, UK
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32
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Abstract
Several cytoskeletal proteins have been shown to interact in vitro with, and in some cases are regulated by, specific membrane lipids. In some cases, evidence for in situ interactions has been provided. The molecular basis for such interactions is now being unravelled. At least five structurally distinct types of lipid-binding sites in cytoskeletal proteins have been identified. However, our understanding of the physiological role of such interactions is still limited. Precise knowledge about the binding-site structures and the actual amino acid residues involved should now enable the expression of mutant proteins that specifically lack the ability to interact with lipids. The impact of these mutations on protein location and function can then be assessed.
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Affiliation(s)
- V Niggli
- Dept of Pathology, University of Bern, Murtenstrasse 31, CH-3010 Bern, Switzerland.
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