DOCSLIB.ORG

Direct Binding of Phosphatidylglycerol at Specific Sites Modulates

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Direct Binding of Phosphatidylglycerol at Specific Sites Modulates bioRxiv preprint doi: https://doi.org/10.1101/722512; this version posted August 7, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 2 3 4 5 6 7 8 9 Direct Binding of Phosphatidylglycerol at Specific Sites Modulates 10 Desensitization of a Pentameric Ligand-Gated Ion Channel 11 12 13 Ailing Tong1, John T. Petroff II1, Fong-Fu Hsu2, Philipp A. M. Schmidpeter3, Crina M. Nimigean3, 14 Liam Sharp4, Grace Brannigan4,5, Wayland W. L. Cheng1,* 15 16 From the Departments of 1Anesthesiology, and 2Internal Medicine, Mass Spectrometry 17 Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Washington 18 University in St. Louis, MO, USA, 3Departments of Anesthesiology, and Physiology and 19 Biophysics, Weill Cornell Medicine, NY, USA, and the 4Center for Computational and Integrative 20 Biology and 5Department of Physics, Rutgers University, Camden, NJ, USA. 21 22 23 *To whom correspondence should be addressed: Professor Wayland W. L. Cheng, Department 24 of Anesthesiology, Washington University School of Medicine, Campus Box 8054, St. Louis, MO 25 63110. Telephone: (314)273-7958; E-mail: [email protected] 26 bioRxiv preprint doi: https://doi.org/10.1101/722512; this version posted August 7, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 27 Abstract 28 Pentameric ligand-gated ion channels (pLGICs) are essential determinants of synaptic 29 transmission, and are modulated by specific lipids including anionic phospholipids. The exact 30 modulatory effect of anionic phospholipids in pLGICs and the mechanism of this effect are not 31 well understood. Using native mass spectrometry, coarse-grained molecular dynamics 32 simulations and functional assays, we show that the anionic phospholipid, 1-palmitoyl-2-oleoyl- 33 phosphatidylglycerol (POPG), preferentially binds to and stabilizes the pLGIC, Erwinia ligand- 34 gated ion channel (ELIC), and decreases ELIC desensitization. Mutations of five arginines located 35 in the interfacial regions of the transmembrane domain (TMD) reduce POPG binding, and a 36 subset of these mutations increase ELIC desensitization. In contrast, the L240A mutant known to 37 decrease ELIC desensitization, increases POPG binding. The results support a mechanism by 38 which POPG stabilizes the open state of ELIC relative to the desensitized state by direct binding 39 at specific sites. 40 41 Introduction 42 Pentameric ligand-gated ion channels (pLGICs) are essential determinants of synaptic 43 transmission, and the targets of many allosteric modulators including general anesthetics and 44 anti-epileptics (1). These ion channels are embedded in a heterogeneous and dynamic lipid 45 environment (2), and the presence of specific lipids fine-tunes the function of pLGICs and may 46 play a role in regulating neuronal excitability and drug sensitivity (3-5). One nearly ubiquitous 47 example is that of anionic phospholipids, which are known to modulate pentameric ligand-gated 48 ion channels (pLGICs) such as the nicotinic acetylcholine receptor (nAchR) (6), as well as inward 49 rectifying potassium channels (7), K(2P) channels (8), voltage-gated potassium channels (9, 10), 50 and cyclic nucleotide-gated channels (11). In pLGICs, anionic phospholipids have been shown to 51 shift the conformational equilibrium of the channel from an uncoupled or desensitized state to a 52 resting state, in which agonist binding is effectively coupled to channel activation (12-14). 2 bioRxiv preprint doi: https://doi.org/10.1101/722512; this version posted August 7, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 53 Studies of lipid modulation of ion channel function including modulation of pLGICs have 54 focused on two central questions: 1) what is the exact effect of the lipid on channel function and 55 structure, and 2) is the effect attributable to direct binding of the lipid at specific sites? Torpedo 56 nAchR channel activity measured from flux assays (6, 15, 16) and agonist-induced conformational 57 changes (13, 17) depend on anionic phospholipids. However, only a few studies have employed 58 fast solution changes to measure current responses of pLGICs in model membranes (18), which 59 is necessary to distinguish the effect of lipids on channel gating, specifically transitions between 60 resting, open and desensitized states. With regard to lipid binding, early studies using electron 61 paramagnetic resonance (EPR) of spin-labeled lipids or lipid-induced modification of fluorescent 62 probes revealed an immobilized layer of lipids surrounding nAchRs that is enriched for certain 63 phospholipids (19, 20) with lipids occupying specific sites (21, 22). These approaches are, 64 however, an indirect means to examine lipid binding to ion channels. More recently, crystal 65 structures of the pLGIC, Gloeobacter ligand-gated ion channel (GLIC), revealed bound, co- 66 purified phospholipids in a putative open structure, and the absence of one of these phospholipids 67 in a locally-closed structure (23, 24). Similarly, a putative desensitized structure of GLIC with a 68 bound polyunsaturated fatty acid showed loss of the aforementioned phospholipid density that is 69 bound to the open state (25). Both of these studies suggest that bound phospholipids at specific 70 sites stabilize the open state of the channel, although the identity of these lipids remains unknown. 71 Furthermore, the absence of a lipid density in a crystal structure is not necessarily an indication 72 of lack of binding. 73 Native mass spectrometry (MS) has proven to be a powerful tool to directly measure 74 binding of endogenous and exogenous lipids to membrane proteins (26, 27). In addition, coarse- 75 grained molecular dynamics (MD) simulations provide a complementary approach to examine 76 lipid interactions with membrane-embedded pLGICs at time scales that allow equilibration of lipid 77 binding sites (28, 29). We sought to determine whether phospholipids bind directly and selectively 78 to a pLGIC by native MS and coarse-grained MD simulations, and whether specific binding 3 bioRxiv preprint doi: https://doi.org/10.1101/722512; this version posted August 7, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 79 interactions modulate channel function by measuring ELIC activity in liposomes of defined lipid 80 composition. Erwinia ligand-gated ion channel (ELIC), a prototypical pLGIC and biochemically 81 tractable target, is also sensitive to its lipid environment. ELIC was found to be inactive when 82 reconstituted in 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) membranes fused to Xenopus 83 oocyte membranes, similar to the nAchR (30). After optimizing native MS for ELIC, we 84 demonstrate that phospholipids directly bind to ELIC, with more binding observed for the anionic 85 phospholipid, 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) compared to zwitterionic 86 phospholipids, 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE) and POPC. Consistent 87 with this finding, coarse-grained simulations of ELIC in a lipid bilayer show enrichment of annular 88 POPG compared to POPC or POPE. In addition, POPG selectively stabilizes ELIC against 89 thermal denaturation indicative of a specific binding interaction, and reduces channel 90 desensitization. Mutations of five arginines at the transmembrane domain (TMD) intracellular and 91 extracellular interfaces decrease POPG binding while a subset of these mutations increase 92 desensitization. Likewise, the L240A mutant, which reduces desensitization, increases POPG 93 binding. The results support the hypothesis that anionic phospholipids stabilize the open state of 94 pLGICs by direct binding to sites in the TMD adjacent to the lipid-facing transmembrane helix 4 95 (TM4) (3). 96 97 Results 98 99 Selective binding of phospholipids to ELIC 100 Native MS of ELIC purified in dodecyl maltoside (DDM) was optimized on a Q-Exactive 101 EMR mass spectrometer as previously described (27). Optimal desolvation of the pentamer 102 required activation energies that resulted in some dissociation into tetramer and monomer (Fig. 103 1A). Nevertheless, both the pentamer and tetramer species showed multiple bound small 104 molecules of ~750 Da, likely corresponding to co-purified phospholipids (up to 8 and 6 lipids per 105 multimer were observed for the pentamer and tetramer, respectively) (Fig. 1A). To determine the 4 bioRxiv preprint doi: https://doi.org/10.1101/722512; this version posted August 7, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Figure 1. POPG binds selectively to ELIC. (A) Native MS spectra of ELIC in DDM, C10E5, and C10E5 with 12 µM POPG. Left shows full spectra and right shows deconvoluted spectra. (B) Deconvoluted spectra of ELIC in 12 µM of the indicated phospholipid. (C) Plot of the average number of bound phospholipids per pentamer at varying concentrations of POPG, POPE and POPC (n=3-6, ±SD). 106 identity of these lipids, we performed a lipid extraction from the purified ELIC preparation, and 107 analyzed the
Load more

Recommended publications
  • Suramin Alters Phosphoinositide Synthesis and Inhibits Growth Factor Receptor Binding in HT-29 Cells'
    (CANCER RESEARCH 50. 6490-6496. October 15. 1990] Suramin Alters Phosphoinositide Synthesis and Inhibits Growth Factor Receptor Binding in HT-29 Cells' Reinhard Kopp2 and Andreas Pfeiffer Departments of Surgery and Internal Medicine II, Klinikum (irosshadern. University of Munich, West Germany ABSTRACT levels and a stimulation of calcium/calmodulin kinases. Di acylglycerol activates protein kinase C, a family of Ca2+-sensi- Initiation of cell growth frequently involves activation of growth factor tive and phospholipid-dependent isoenzymes, known to phos- receptor-coupled u rosine kinases and stimulation of the phosphoinositide phorylate regulatory proteins and to elevate cytosolic pH levels second messenger system. The antitrypanosomal and antifiliarial drug suramin has been shown to exert antiproliferative activities by inhibition (5, 6). Activation of protein kinase C by phorbol esters and of growth factor receptor binding. We therefore investigated the effect of elevation of intracellular calcium levels by calcium ionophores suramin on epidermal growth factor receptor-binding characteristics and, have been shown to be mitogenically active cofactors during the additionally, searched for effects on basal or cholinergically stimulated initiation of DNA synthesis (7-10). phospholipid metabolism in HT-29 cells. HT-29 colon carcinoma cells have recently been shown to Suramin caused a dose-dependent and noncompetitive inhibition of produce EGF/transforming growth factor «and insulin-like '"I-epidermal growth factor binding (concentration producing 50% inhi growth factor 1-like activities (11), indicating a possible auto bition, 44.2 Mg/ml)but did not alter muscarinic receptor binding. Suramin did not affect the basal '-'I* incorporation into phosphoinositides at crine proliferative effect of these growth factors.
    [Show full text]
  • Inositol Triphosphate-Triggered Calcium Release Blocks Lipid Exchange at Endoplasmic Reticulum- Golgi Contact Sites
    ARTICLE https://doi.org/10.1038/s41467-021-22882-x OPEN Inositol triphosphate-triggered calcium release blocks lipid exchange at endoplasmic reticulum- Golgi contact sites Mouhannad Malek 1, Anna M. Wawrzyniak 1, Peter Koch1, Christian Lüchtenborg2, Manuel Hessenberger1, ✉ Timo Sachsenheimer2, Wonyul Jang 1, Britta Brügger 2 & Volker Haucke 1,3 fi 1234567890():,; Vesicular traf c and membrane contact sites between organelles enable the exchange of proteins, lipids, and metabolites. Recruitment of tethers to contact sites between the endo- plasmic reticulum (ER) and the plasma membrane is often triggered by calcium. Here we reveal a function for calcium in the repression of cholesterol export at membrane contact sites between the ER and the Golgi complex. We show that calcium efflux from ER stores induced by inositol-triphosphate [IP3] accumulation upon loss of the inositol 5-phosphatase INPP5A or receptor signaling triggers depletion of cholesterol and associated Gb3 from the cell surface, resulting in a blockade of clathrin-independent endocytosis (CIE) of Shiga toxin. This phenotype is caused by the calcium-induced dissociation of oxysterol binding protein (OSBP) from the Golgi complex and from VAP-containing membrane contact sites. Our findings reveal a crucial function for INPP5A-mediated IP3 hydrolysis in the control of lipid exchange at membrane contact sites. 1 Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany. 2 Heidelberg University Biochemistry Center (BZH), Heidelberg ✉ University, Heidelberg, Germany. 3 Faculty of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany. email: [email protected] NATURE COMMUNICATIONS | (2021) 12:2673 | https://doi.org/10.1038/s41467-021-22882-x | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-021-22882-x ellular membrane homeostasis and the exchange of Results material between compartments can occur by vesicular INPP5A is required for Gb3-mediated Shiga toxin cell entry.
    [Show full text]
  • Regulation of Signaling and Metabolism by Lipin-Mediated Phosphatidic Acid Phosphohydrolase Activity
    biomolecules Review Regulation of Signaling and Metabolism by Lipin-mediated Phosphatidic Acid Phosphohydrolase Activity Andrew J. Lutkewitte and Brian N. Finck * Center for Human Nutrition, Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, Euclid Avenue, Campus Box 8031, St. Louis, MO 63110, USA; [email protected] * Correspondence: bfi[email protected]; Tel: +1-3143628963 Received: 4 September 2020; Accepted: 24 September 2020; Published: 29 September 2020 Abstract: Phosphatidic acid (PA) is a glycerophospholipid intermediate in the triglyceride synthesis pathway that has incredibly important structural functions as a component of cell membranes and dynamic effects on intracellular and intercellular signaling pathways. Although there are many pathways to synthesize and degrade PA, a family of PA phosphohydrolases (lipin family proteins) that generate diacylglycerol constitute the primary pathway for PA incorporation into triglycerides. Previously, it was believed that the pool of PA used to synthesize triglyceride was distinct, compartmentalized, and did not widely intersect with signaling pathways. However, we now know that modulating the activity of lipin 1 has profound effects on signaling in a variety of cell types. Indeed, in most tissues except adipose tissue, lipin-mediated PA phosphohydrolase activity is far from limiting for normal rates of triglyceride synthesis, but rather impacts critical signaling cascades that control cellular homeostasis. In this review, we will discuss how lipin-mediated control of PA concentrations regulates metabolism and signaling in mammalian organisms. Keywords: phosphatidic acid; diacylglycerol; lipin; signaling 1. Introduction Foundational work many decades ago by the laboratory of Dr. Eugene Kennedy defined the four sequential enzymatic steps by which three fatty acyl groups were esterified onto the glycerol-3-phosphate backbone to synthesize triglyceride [1].
    [Show full text]
  • Phosphatidylglycerol Incorporates Into Cardiolipin to Improve
    www.nature.com/scientificreports OPEN Phosphatidylglycerol Incorporates into Cardiolipin to Improve Mitochondrial Activity and Inhibits Received: 3 July 2017 Accepted: 7 March 2018 Infammation Published: xx xx xxxx Wei-Wei Chen1, Yu-Jen Chao1, Wan-Hsin Chang1, Jui-Fen Chan1 & Yuan-Hao Howard Hsu1,2 Chronic infammation and concomitant oxidative stress can induce mitochondrial dysfunction due to cardiolipin (CL) abnormalities in the mitochondrial inner membrane. To examine the responses of mitochondria to infammation, macrophage-like RAW264.7 cells were activated by Kdo2-Lipid A (KLA) in our infammation model, and then the mitochondrial CL profle, mitochondrial activity, and the mRNA expression of CL metabolism-related genes were examined. The results demonstrated that KLA activation caused CL desaturation and the partial loss of mitochondrial activity. KLA activation also induced the gene upregulation of cyclooxygenase (COX)-2 and phospholipid scramblase 3, and the gene downregulation of COX-1, lipoxygenase 5, and Δ-6 desaturase. We further examined the phophatidylglycerol (PG) inhibition efects on infammation. PG supplementation resulted in a 358- fold inhibition of COX-2 mRNA expression. PG(18:1)2 and PG(18:2)2 were incorporated into CLs to considerably alter the CL profle. The decreased CL and increased monolysocardiolipin (MLCL) quantity resulted in a reduced CL/MLCL ratio. KLA-activated macrophages responded diferentially to PG(18:1)2 and PG(18:2)2 supplementation. Specifcally, PG(18:1)2 induced less changes in the CL/MLCL ratio than did PG(18:2)2, which resulted in a 50% reduction in the CL/MLCL ratio. However, both PG types rescued 20–30% of the mitochondrial activity that had been afected by KLA activation.
    [Show full text]
  • Lipid–Protein and Protein–Protein Interactions in the Pulmonary Surfactant System and Their Role in Lung Homeostasis
    International Journal of Molecular Sciences Review Lipid–Protein and Protein–Protein Interactions in the Pulmonary Surfactant System and Their Role in Lung Homeostasis Olga Cañadas 1,2,Bárbara Olmeda 1,2, Alejandro Alonso 1,2 and Jesús Pérez-Gil 1,2,* 1 Departament of Biochemistry and Molecular Biology, Faculty of Biology, Complutense University, 28040 Madrid, Spain; [email protected] (O.C.); [email protected] (B.O.); [email protected] (A.A.) 2 Research Institut “Hospital Doce de Octubre (imasdoce)”, 28040 Madrid, Spain * Correspondence: [email protected]; Tel.: +34-913944994 Received: 9 May 2020; Accepted: 22 May 2020; Published: 25 May 2020 Abstract: Pulmonary surfactant is a lipid/protein complex synthesized by the alveolar epithelium and secreted into the airspaces, where it coats and protects the large respiratory air–liquid interface. Surfactant, assembled as a complex network of membranous structures, integrates elements in charge of reducing surface tension to a minimum along the breathing cycle, thus maintaining a large surface open to gas exchange and also protecting the lung and the body from the entrance of a myriad of potentially pathogenic entities. Different molecules in the surfactant establish a multivalent crosstalk with the epithelium, the immune system and the lung microbiota, constituting a crucial platform to sustain homeostasis, under health and disease. This review summarizes some of the most important molecules and interactions within lung surfactant and how multiple lipid–protein and protein–protein interactions contribute to the proper maintenance of an operative respiratory surface. Keywords: pulmonary surfactant film; surfactant metabolism; surface tension; respiratory air–liquid interface; inflammation; antimicrobial activity; apoptosis; efferocytosis; tissue repair 1.
    [Show full text]
  • Studies of the Structure of Potassium Channel Kcsa in the Open Conformation and the Effect of Anionic Lipids on Channel Inactivation
    Studies of the structure of potassium channel KcsA in the open conformation and the effect of anionic lipids on channel inactivation Dongyu (Allison) Zhang Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences COLUMBIA UNIVERSITY 2019 © 2019 Dongyu Zhang All rights reserved Abstract Studies of the structure of potassium channel KcsA in the open conformation and the effect of anionic lipids on channel inactivation Dongyu Zhang Membrane proteins play a vital role in cellular processes. In this thesis, we use KcsA, a prokaryotic potassium channel, as a model to investigate the gating mechanism of ion channels and the effect of anionic lipids on the channel activity using solid-state NMR spectroscopy. KcsA activity is known to be highly dependent on the presence of negatively charged lipids. Multiple crystal structures combined with biochemistry assays suggest that KcsA is co-purified with anionic lipids with phosphatidylglycerol headgroup. Here, we identified this specifically bound, isotopically labeled lipid in the protein 13C-13C correlation spectra. Our results reveal that the lipid cross peaks show stronger intensity when the channel is in the inactivated state compared to the activated state, which indicates a stronger protein-lipid interaction when KcsA is inactivated. In addition, our data shows that including anionic lipids into proteoliposomes leads to a weaker potassium ion affinity at the selectivity filter. Considering ion loss as a model of inactivation, our results suggest anionic lipids promote channel inactivation. However, the surface charge is not the only physical parameter that regulates channel gating or conformational preference.
    [Show full text]
  • The Role of Phosphatidylserine in Recognition of Apoptotic Cells by Phagocytes
    Cell Death and Differentiation (1998) 5, 551 ± 562 1998 Stockton Press All rights reserved 13509047/98 $12.00 http://www.stockton-press.co.uk/cdd Review The role of phosphatidylserine in recognition of apoptotic cells by phagocytes Valerie A. Fadok1,2, Donna L. Bratton1, S. Courtney Frasch1, epithelial cells and vascular smooth muscle cells). To date, Mary L. Warner1 and Peter M. Henson1 there have been a number of receptors described for macrophages and other cells which bind to apoptotic cells 1 Department of Pediatrics, National Jewish Medical and Research Center, 1400 and mediate their uptake. These include lectin-like receptors Jackson Street, Denver, Colorado 80206 USA (Duvall et al, 1985, Dini et al, 1992; 1995; Hall et al, 1994; 2 corresponding author: tel: 1-303-398-1281 fax: 1-303-398-1381 Morris et al, 1994; Falasca et al, 1996), the vitronectin receptor email: [email protected] avb3 (Savill et al, 1990; Hall et al, 1994; Hughes et al, 1997), CD36 (Savill et al, 1992), an uncharacterized phosphatidyl- Received: 15.10.97; revised: 23.3.98; accepted: 2.4.98 Edited by M. Piacentini serine-recognizing receptor (Fadok et al, 1992a,b, 1993; Pradhan et al, 1997), CD14 (Flora and Gregory 1994; Devitt et al, 1998), and scavenger receptors (Sambrano and Steinberg, Abstract 1995; Fukasawa et al, 1996; Platt et al, 1996; Murao et al, 1997). The ABC1 transporter, also involved in uptake of Exposure of phosphatidylserine on the outer leaflet of the mammalian apoptotic cells, has recently been shown to plasma membrane is a surface change common to many mediate anion transport (Luciani and Chimini, 1996; Becq et apoptotic cells.
    [Show full text]
  • New Insights Into Multiple Sclerosis Mechanisms: Lipids on the Track to Control Inflammation and Neurodegeneration
    International Journal of Molecular Sciences Review New Insights into Multiple Sclerosis Mechanisms: Lipids on the Track to Control Inflammation and Neurodegeneration Maria Podbielska 1,2,* , Joan O’Keeffe 3 and Anna Pokryszko-Dragan 4 1 Department of Biochemistry & Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA 2 Laboratory of Microbiome Immunobiology, Ludwik Hirszfeld Institute of Immunology & Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland 3 Department of Analytical, Biopharmaceutical and Medical Sciences, School of Science & Computing, Galway-Mayo Institute of Technology, Galway, Ireland; [email protected] 4 Department of Neurology, Wroclaw Medical University, 50-556 Wroclaw, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-71-370-9912 Abstract: Multiple sclerosis (MS) is a central nervous system disease with complex pathogenesis, including two main processes: immune-mediated inflammatory demyelination and progressive degeneration with axonal loss. Despite recent progress in our understanding and management of MS, availability of sensitive and specific biomarkers for these both processes, as well as neuroprotec- tive therapeutic options targeted at progressive phase of disease, are still being sought. Given their abundance in the myelin sheath, lipids are believed to play a central role in underlying immunopatho- genesis in MS and seem to be a promising subject of investigation in this field. On the basis of our previous research and a review of the literature, we discuss the current understanding of lipid-related mechanisms involved in active relapse, remission, and progression of MS. These insights highlight Citation: Podbielska, M.; O’Keeffe, J.; potential usefulness of lipid markers in prediction or monitoring the course of MS, particularly in its Pokryszko-Dragan, A.
    [Show full text]
  • Formation of Lipophilic Complexes with Phosphatidic Acid And
    476 Notizen Action of Polymyxin B on Bacterial Membranes, II Mono-A^-acetyl-14C-derivatives of polymyxin B (PX) Formation of Lipophilic Complexes with were prepared as previously reported 6. The specific activity was 14.7 juCi/jumole. Polymyxin B sulfate Phosphatidic Acid and Phosphatidylglycerol (sterile powder) was a gift of Pfizer GmbH (Karls­ M. Teuber ruhe, Germany). Radioactivity was determined in a Abteilung Mikrobiologie, Institut für Botanik, Technische toluene based scintillation liquid with a Beckman Universität München LSI00 spectrometer. (Z. Naturforsch. 28 c, 476 — 477 [1973] ; received Since it is generally assumed that phospholipids April 9, 1973) are arranged in biological membranes in bilayers Salmonella typhimurium, phospholipids, cell membrane, forming the hydrophobic permeability barrier7, it polymyxin B, antibiotic was of interest to search for a polymyxin-phospho- The bactericidal mechanism of action of poly­ lipid complex which would be stable in a hydro- myxin B against susceptible bacteria has been sug­ phobic environment. Because the polymyxin mole­ gested to result from electrostatic interactions of the cule is very polar at neutral pH (5 free amino- basic polypeptide antibiotic with acidic cell envelope groups) it does not migrate away from the origin phospholipids 1,2. This process causes the breakdown when chromatographed with chloroform-methanol- of the selective permeability barrier of the cyto­ water on Whatman No. 1 paper. However, when plasmic membrane, and finally cell death. The mixed with PA or PG, part of the radioactive anti- identities of the polymyxin receptor molecules in sensitive bacteria, however, have never been deter­ mined with certainty. The problem is further com­ plicated by the fact that polymyxin exhibits a strikingly selective activity against Gram-negative bacteria3 which, in addition to the plasma mem­ brane, possess a second membrane structure, the outer membrane or plastic layer composed of pro­ teins, lipopolysaccharide and phospholipids4.
    [Show full text]
  • Phospholipids Across Scales: Lipid Patterns and Plant Development Leia Axelle Colin, Yvon Jaillais
    Phospholipids across scales: lipid patterns and plant development Leia Axelle Colin, Yvon Jaillais To cite this version: Leia Axelle Colin, Yvon Jaillais. Phospholipids across scales: lipid patterns and plant develop- ment. Current Opinion in Plant Biology, Elsevier, 2020, 53, pp.1-9. 10.1016/j.pbi.2019.08.007. hal-02349861 HAL Id: hal-02349861 https://hal.archives-ouvertes.fr/hal-02349861 Submitted on 5 Nov 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution - NonCommercial - NoDerivatives| 4.0 International License Phospholipids across scales: lipid patterns and plant development Leia Axelle Colin and Yvon Jaillais Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342 Lyon, France Corresponding author: Yvon Jaillais ([email protected]) Abstract: Phospholipids are major building blocks of cell membranes and as such they have a key structural role in maintaining their integrity as a hydrophobic barrier. However, phospholipids not only have structural but also regulatory functions that are involved in a myriad of signaling pathways. Integrative approaches in plants recently revealed that certain phospholipids have distinct patterns of accumulation at the tissue or organ scales, which turned out to be important cues in a developmental context.
    [Show full text]
  • Analysis of Labeling and Clearance of Lung Surfactant Phospholipids in Rabbit: EVIDENCE of BIDIRECTIONAL SURFACTANT FLUX BETWEEN LAMELLAR BODIES and ALVEOLAR LAVAGE
    Analysis of Labeling and Clearance of Lung Surfactant Phospholipids in Rabbit: EVIDENCE OF BIDIRECTIONAL SURFACTANT FLUX BETWEEN LAMELLAR BODIES AND ALVEOLAR LAVAGE Mikko Hallman, … , Benita L. Epstein, Louis Gluck J Clin Invest. 1981;68(3):742-751. https://doi.org/10.1172/JCI110310. Turnover and clearance of lung surfactant phospholipids were studied with particular reference to myoinositol-induced perturbation in the acidic phospholipids. Administration of myoinositol decreased [3H]palmitate and [32P]phosphate incorporation into phosphatidylglycerol by 80-90% in whole lung, and by 94-99% in lamellar bodies and in alveolar lavage. The increased incorporation of radioactive isotopes into phosphatidylinositol following myoinositol, was inverse to the decrease in phosphatidyl-glycerol incorporation. Myoinositol treatment affected neither content nor labeling of phosphatidylcholine or disaturated phosphatidylcholine as studied within 50 h of administration. Phosphatidylglycerol was pulse labeled by intravenous [32P]phosphate and [3H]palmitate, followed by myoinositol. The biological half-lives of phosphatidylglycerol in the microsomal fraction, lamellar bodies, and alveolar lavage were 1.6, 4.6, 5.4 h (with 3H), and 2.8, 6.5, 7.0 h (with 32P), respectively. 32P-labeled lung surfactant tracer was applied to the airways in saline suspension and the clearance of phospholipid radioactivity was measured in alveolar lavage, alveolar macrophages, lamellar bodies and lung homogenates. The clearance rates of phosphatidylcholine, disaturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylinositol as studied in whole lung over 6 h were 3.4-5.8% h. Only a small amount of phospholipid radioactivity was recovered in the alveolar macrophage fraction (including bis-[monoacylglycerol]phosphate). Phospholipid radioactivity in alveolar lavage fell to 40-70% of the maximum during the 1st h, and to 5-18% over the next 6 h.
    [Show full text]
  • Current Research in Phospholipids and Their Use in Drug Delivery
    pharmaceutics Review Review TheThe PhospholipidPhospholipid ResearchResearch Center:Center: CurrentCurrent ResearchResearch inin PhospholipidsPhospholipids andand TheirTheir UseUse inin DrugDrug DeliveryDelivery SimonSimon DrescherDrescher ** andand Peter Peter van van Hoogevest Hoogevest PhospholipidPhospholipid ResearchResearch Center,Center, ImIm NeuenheimerNeuenheimerFeld Feld 515, 515, 69120 69120 Heidelberg, Heidelberg, Germany; Germany; [email protected] [email protected] * Correspondence: [email protected]; Tel.: +49-06221-588-83-60 * Correspondence: [email protected]; Tel.: +49-06221-588-83-60 Received:Received: 24 November 2020;2020; Accepted:Accepted: 14 December 2020; Published: 18 December 2020 Abstract:Abstract: ThisThis reviewreview summarizessummarizes thethe researchresearch onon phospholipidsphospholipids andand theirtheir useuse forfor drugdrug deliverydelivery relatedrelated toto thethe PhospholipidPhospholipid ResearchResearch CenterCenter HeidelbergHeidelberg (PRC).(PRC). TheThe focusfocus isis onon projectsprojects thatthat havehave beenbeen approvedapproved by by the the PRC PRC since since 2017 2017 and areand currently are currently still ongoing still ongoing or have recentlyor have been recently completed. been Thecompleted. different The projects different cover projects all facets cover of all phospholipid facets of phospholipid research, fromresearch, basic from to applied basic to research, applied includingresearch, including the
    [Show full text]