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Arachidonic Acid Kills Staphylococcus aureus through a Lipid Peroxidation Mechanism.
Beavers WN, Monteith AJ, Amarnath V, Mernaugh RL, Roberts LJ, Chazin WJ, Davies SS, Skaar EP
(2019) mBio 10:
MeSH Terms: Animals, Anti-Bacterial Agents, Arachidonic Acid, Brain, Dose-Response Relationship, Drug, Drug Resistance, Bacterial, Female, Kidney, Lipid Peroxidation, Lipids, Mice, Mice, Inbred BALB C, Microbial Sensitivity Tests, Mutation, Neutrophils, Oxidative Stress, Reactive Oxygen Species, Spleen, Staphylococcal Infections, Staphylococcus aureus, Teichoic Acids
Show Abstract · Added March 11, 2020
infects every niche of the human host. In response to microbial infection, vertebrates have an arsenal of antimicrobial compounds that inhibit bacterial growth or kill bacterial cells. One class of antimicrobial compounds consists of polyunsaturated fatty acids, which are highly abundant in eukaryotes and encountered by at the host-pathogen interface. Arachidonic acid (AA) is one of the most abundant polyunsaturated fatty acids in vertebrates and is released in large amounts during the oxidative burst. Most of the released AA is converted to bioactive signaling molecules, but, independently of its role in inflammatory signaling, AA is toxic to Here, we report that AA kills through a lipid peroxidation mechanism whereby AA is oxidized to reactive electrophiles that modify macromolecules, eliciting toxicity. This process is rescued by cotreatment with antioxidants as well as in a strain genetically inactivated for (USA300 mutant) that produces lower levels of reactive oxygen species. However, resistance to AA stress in the USA300 mutant comes at a cost, making the mutant more susceptible to β-lactam antibiotics and attenuated for pathogenesis in a murine infection model compared to the parental methicillin-resistant (MRSA) strain, indicating that resistance to AA toxicity increases susceptibility to other stressors encountered during infection. This report defines the mechanism by which AA is toxic to and identifies lipid peroxidation as a pathway that can be modulated for the development of future therapeutics to treat infections. Despite the ability of the human immune system to generate a plethora of molecules to control infections, is among the pathogens with the greatest impact on human health. One class of host molecules toxic to consists of polyunsaturated fatty acids. Here, we investigated the antibacterial properties of arachidonic acid, one of the most abundant polyunsaturated fatty acids in humans, and discovered that the mechanism of toxicity against proceeds through lipid peroxidation. A better understanding of the molecular mechanisms by which the immune system kills , and by which avoids host killing, will enable the optimal design of therapeutics that complement the ability of the vertebrate immune response to eliminate infections.
Copyright © 2019 Beavers et al.
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21 MeSH Terms
Upgraded molecular models of the human KCNQ1 potassium channel.
Kuenze G, Duran AM, Woods H, Brewer KR, McDonald EF, Vanoye CG, George AL, Sanders CR, Meiler J
(2019) PLoS One 14: e0220415
MeSH Terms: Humans, Hydrogen Bonding, KCNQ1 Potassium Channel, Lipids, Loss of Function Mutation, Models, Molecular, Molecular Docking Simulation, Molecular Dynamics Simulation, Protein Binding, Protein Conformation, Structure-Activity Relationship
Show Abstract · Added March 21, 2020
The voltage-gated potassium channel KCNQ1 (KV7.1) assembles with the KCNE1 accessory protein to generate the slow delayed rectifier current, IKS, which is critical for membrane repolarization as part of the cardiac action potential. Loss-of-function (LOF) mutations in KCNQ1 are the most common cause of congenital long QT syndrome (LQTS), type 1 LQTS, an inherited genetic predisposition to cardiac arrhythmia and sudden cardiac death. A detailed structural understanding of KCNQ1 is needed to elucidate the molecular basis for KCNQ1 LOF in disease and to enable structure-guided design of new anti-arrhythmic drugs. In this work, advanced structural models of human KCNQ1 in the resting/closed and activated/open states were developed by Rosetta homology modeling guided by newly available experimentally-based templates: X. leavis KCNQ1 and various resting voltage sensor structures. Using molecular dynamics (MD) simulations, the capacity of the models to describe experimentally established channel properties including state-dependent voltage sensor gating charge interactions and pore conformations, PIP2 binding sites, and voltage sensor-pore domain interactions were validated. Rosetta energy calculations were applied to assess the utility of each model in interpreting mutation-evoked KCNQ1 dysfunction by predicting the change in protein thermodynamic stability for 50 experimentally characterized KCNQ1 variants with mutations located in the voltage-sensing domain. Energetic destabilization was successfully predicted for folding-defective KCNQ1 LOF mutants whereas wild type-like mutants exhibited no significant energetic frustrations, which supports growing evidence that mutation-induced protein destabilization is an especially common cause of KCNQ1 dysfunction. The new KCNQ1 Rosetta models provide helpful tools in the study of the structural basis for KCNQ1 function and can be used to generate hypotheses to explain KCNQ1 dysfunction.
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Two Specific Sulfatide Species Are Dysregulated during Renal Development in a Mouse Model of Alport Syndrome.
Gessel MM, Spraggins JM, Voziyan PA, Abrahamson DR, Caprioli RM, Hudson BG
(2019) Lipids 54: 411-418
MeSH Terms: Animals, Disease Models, Animal, Kidney Tubules, Lipid Metabolism, Mice, Nephritis, Hereditary, Sulfoglycosphingolipids
Show Abstract · Added January 22, 2020
Alport syndrome is caused by mutations in collagen IV that alter the morphology of renal glomerular basement membrane. Mutations result in proteinuria, tubulointerstitial fibrosis, and renal failure but the pathogenic mechanisms are not fully understood. Using imaging mass spectrometry, we aimed to determine whether the spatial and/or temporal patterns of renal lipids are perturbed during the development of Alport syndrome in the mouse model. Our results show that most sulfatides are present at similar levels in both the wild-type (WT) and the Alport kidneys, with the exception of two specific sulfatide species, SulfoHex-Cer(d18:2/24:0) and SulfoHex-Cer(d18:2/16:0). In the Alport but not in WT kidneys, the levels of these species mirror the previously described abnormal laminin expression in Alport syndrome. The presence of these sulfatides in renal tubules but not in glomeruli suggests that this specific aberrant lipid pattern may be related to the development of tubulointerstitial fibrosis in Alport disease.
© 2019 AOCS.
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7 MeSH Terms
Plasma apoM and S1P levels are inversely associated with mortality in African Americans with type 2 diabetes mellitus.
Liu M, Frej C, Langefeld CD, Divers J, Bowden DW, Carr JJ, Gebre AK, Xu J, Larsson B, Dahlbäck B, Freedman BI, Parks JS
(2019) J Lipid Res 60: 1425-1431
MeSH Terms: African Americans, Apolipoproteins M, Biomarkers, Diabetes Mellitus, Type 2, Disease-Free Survival, Female, Humans, Lysophospholipids, Male, Middle Aged, Sphingosine, Survival Rate
Show Abstract · Added January 10, 2020
apoM is a minor HDL apolipoprotein and carrier for sphingosine-1-phosphate (S1P). HDL apoM and S1P concentrations are inversely associated with atherosclerosis progression in rodents. We evaluated associations between plasma concentrations of S1P, plasma concentrations of apoM, and HDL apoM levels with prevalent subclinical atherosclerosis and mortality in the African American-Diabetes Heart Study participants (N = 545). Associations between plasma S1P, plasma apoM, and HDL apoM with subclinical atherosclerosis and mortality were assessed using multivariate parametric, nonparametric, and Cox proportional hazards models. At baseline, participants' median (25th percentile, 75th percentile) age was 55 (49, 62) years old and their coronary artery calcium (CAC) mass score was 26.5 (0.0, 346.5). Plasma S1P, plasma apoM, and HDL apoM were not associated with CAC. After 64 (57.6, 70.3) months of follow-up, 81 deaths were recorded. Higher concentrations of plasma S1P [odds ratio (OR) = 0.14, = 0.01] and plasma apoM (OR = 0.10, = 0.02), but not HDL apoM ( = 0.89), were associated with lower mortality after adjusting for age, sex, statin use, CAC, kidney function, and albuminuria. We conclude that plasma S1P and apoM concentrations are inversely and independently associated with mortality, but not CAC, in African Americans with type 2 diabetes after accounting for conventional risk factors.
Copyright © 2019 Liu et al.
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12 MeSH Terms
Transfer of Functional Cargo in Exomeres.
Zhang Q, Higginbotham JN, Jeppesen DK, Yang YP, Li W, McKinley ET, Graves-Deal R, Ping J, Britain CM, Dorsett KA, Hartman CL, Ford DA, Allen RM, Vickers KC, Liu Q, Franklin JL, Bellis SL, Coffey RJ
(2019) Cell Rep 27: 940-954.e6
MeSH Terms: Amphiregulin, Animals, Cell Line, Tumor, Colonic Neoplasms, Dogs, ErbB Receptors, Exosomes, Humans, Lipids, Madin Darby Canine Kidney Cells, Mice, Mice, Knockout, Nanoparticles, Nucleic Acids, Particle Size, Principal Component Analysis, Proteome, Proteomics, Sialyltransferases
Show Abstract · Added April 24, 2019
Exomeres are a recently discovered type of extracellular nanoparticle with no known biological function. Herein, we describe a simple ultracentrifugation-based method for separation of exomeres from exosomes. Exomeres are enriched in Argonaute 1-3 and amyloid precursor protein. We identify distinct functions of exomeres mediated by two of their cargo, the β-galactoside α2,6-sialyltransferase 1 (ST6Gal-I) that α2,6- sialylates N-glycans, and the EGFR ligand, amphiregulin (AREG). Functional ST6Gal-I in exomeres can be transferred to cells, resulting in hypersialylation of recipient cell-surface proteins including β1-integrin. AREG-containing exomeres elicit prolonged EGFR and downstream signaling in recipient cells, modulate EGFR trafficking in normal intestinal organoids, and dramatically enhance the growth of colonic tumor organoids. This study provides a simplified method of exomere isolation and demonstrates that exomeres contain and can transfer functional cargo. These findings underscore the heterogeneity of nanoparticles and should accelerate advances in determining the composition and biological functions of exomeres.
Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.
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19 MeSH Terms
Gastroesophageal Reflux Induces Protein Adducts in the Esophagus.
Caspa Gokulan R, Adcock JM, Zagol-Ikapitte I, Mernaugh R, Williams P, Washington KM, Boutaud O, Oates JA, Dikalov SI, Zaika AI
(2019) Cell Mol Gastroenterol Hepatol 7: 480-482.e7
MeSH Terms: Acetylcysteine, Animals, Benzylamines, Bile Acids and Salts, Cell Line, Cyclic N-Oxides, Esophagus, Gastroesophageal Reflux, Humans, Lipids, Mice, Spin Labels, Tumor Suppressor Protein p53
Added March 26, 2019
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13 MeSH Terms
Ion mobility conformational lipid atlas for high confidence lipidomics.
Leaptrot KL, May JC, Dodds JN, McLean JA
(2019) Nat Commun 10: 985
MeSH Terms: Animals, Databases, Chemical, Lipids, Mass Spectrometry, Metabolomics, Molecular Conformation, Molecular Structure
Show Abstract · Added August 7, 2019
Lipids are highly structurally diverse molecules involved in a wide variety of biological processes. Here, we use high precision ion mobility-mass spectrometry to compile a structural database of 456 mass-resolved collision cross sections (CCS) of sphingolipid and glycerophospholipid species. Our CCS database comprises sphingomyelin, cerebroside, ceramide, phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, and phosphatidic acid classes. Primary differences observed are between lipid categories, with sphingolipids exhibiting 2-6% larger CCSs than glycerophospholipids of similar mass, likely a result of the sphingosine backbone's restriction of the sn1 tail length, limiting gas-phase packing efficiency. Acyl tail length and degree of unsaturation are found to be the primary structural descriptors determining CCS magnitude, with degree of unsaturation being four times as influential per mass unit. The empirical CCS values and previously unmapped quantitative structural trends detailed in this work are expected to facilitate prediction of CCS in broadscale lipidomics research.
1 Communities
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MeSH Terms
Absolute Configurations of Naturally Occurring [5]- and [3]-Ladderanoic Acids: Isolation, Chiroptical Spectroscopy, and Crystallography.
Raghavan V, Johnson JL, Stec DF, Song B, Zajac G, Baranska M, Harris CM, Schley ND, Polavarapu PL, Harris TM
(2018) J Nat Prod 81: 2654-2666
MeSH Terms: Biomass, Bioreactors, Circular Dichroism, Crystallography, X-Ray, Esters, Lipids, Molecular Conformation, Molecular Structure, Spectrum Analysis, Raman, Stereoisomerism
Show Abstract · Added March 3, 2020
We have isolated mixtures of [5]- and [3]-ladderanoic acids 1a and 2a from the biomass of an anammox bioreactor and have separated the acids and their phenacyl esters for the first time by HPLC. The absolute configurations of the naturally occurring acids and their phenacyl esters are assigned as R at the site of side-chain attachment by comparison of experimental specific rotations with corresponding values predicted using quantum chemical (QC) methods. The absolute configurations for 1a and 2a were independently verified by comparison of experimental Raman optical activity spectra with corresponding spectra predicted using QC methods. The configurational assignments of 1a and 2a and of the phenacyl ester of 1a were also confirmed by X-ray crystallography.
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Lysophospholipases cooperate to mediate lipid homeostasis and lysophospholipid signaling.
Wepy JA, Galligan JJ, Kingsley PJ, Xu S, Goodman MC, Tallman KA, Rouzer CA, Marnett LJ
(2019) J Lipid Res 60: 360-374
MeSH Terms: Amino Acid Sequence, Cell Differentiation, Cell Line, Gene Knockout Techniques, Homeostasis, Humans, Hydrolysis, Lysophospholipids, Models, Molecular, Neurons, Protein Conformation, Signal Transduction, Thiolester Hydrolases
Show Abstract · Added April 12, 2019
Lysophospholipids (LysoPLs) are bioactive lipid species involved in cellular signaling processes and the regulation of cell membrane structure. LysoPLs are metabolized through the action of lysophospholipases, including lysophospholipase A1 (LYPLA1) and lysophospholipase A2 (LYPLA2). A new X-ray crystal structure of LYPLA2 compared with a previously published structure of LYPLA1 demonstrated near-identical folding of the two enzymes; however, LYPLA1 and LYPLA2 have displayed distinct substrate specificities in recombinant enzyme assays. To determine how these in vitro substrate preferences translate into a relevant cellular setting and better understand the enzymes' role in LysoPL metabolism, CRISPR-Cas9 technology was utilized to generate stable KOs of and/or in Neuro2a cells. Using these cellular models in combination with a targeted lipidomics approach, LysoPL levels were quantified and compared between cell lines to determine the effect of losing lysophospholipase activity on lipid metabolism. This work suggests that LYPLA1 and LYPLA2 are each able to account for the loss of the other to maintain lipid homeostasis in cells; however, when both are deleted, LysoPL levels are dramatically increased, causing phenotypic and morphological changes to the cells.
Copyright © 2019 Wepy et al.
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13 MeSH Terms
Simplified LC/MS assay for the measurement of isolevuglandin protein adducts in plasma and tissue samples.
Yermalitsky VN, Matafonova E, Tallman K, Li Z, Zackert W, Roberts LJ, Amarnath V, Davies SS
(2019) Anal Biochem 566: 89-101
MeSH Terms: Aldehydes, Animals, Chromatography, Liquid, Ketones, Lipids, Mice, Mice, Inbred C57BL, Protein Processing, Post-Translational, Proteins, Tandem Mass Spectrometry
Show Abstract · Added July 17, 2019
Isolevuglandins (IsoLGs) are a family of highly reactive 4-ketoaldehydes formed by lipid peroxidation that modify the lysyl residues of cellular proteins. Modification of proteins by IsoLGs have been shown to contribute to disease processes such as the development of hypertension. Accurate quantitation of the extent of protein modification by IsoLGs is essential for understanding the mechanisms whereby these modifications contribute to disease and the efficacy of interventions designed to prevent this modification. The previously described LC/MS assay to quantitate IsoLG protein adducts was extremely labor-intensive and time consuming, and while it offered reasonably low intra-day variation for replicate samples, variation when replicate samples were processed on separate days was significant. These limitations significantly restricted utilization of this approach. We therefore performed a series of studies to optimize the assay. We now report a significantly simplified LC/MS assay for measurement of IsoLG protein adducts with increased sensitivity and lower intra-day and inter-day variability.
Copyright © 2018. Published by Elsevier Inc.
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10 MeSH Terms