Lipid Acyl Chain cis Double Bond Position Modulates Membrane Domain Registration/Anti-Registration

2019 ◽  
Vol 141 (40) ◽  
pp. 15884-15890 ◽  
Author(s):  
Siya Zhang ◽  
Xubo Lin
Keyword(s):  
Double Bond ◽  
Acyl Chain ◽  
Double Bond Position ◽  
Membrane Domain

scholarly journals The Gb3-enriched CD59/flotillin plasma membrane domain regulates host cell invasion by Pseudomonas aeruginosa

2021 ◽  
Author(s):  
Annette Brandel ◽  
Sahaja Aigal ◽  
Simon Lagies ◽  
Manuel Schlimpert ◽  
Ana Valeria Meléndez ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Plasma Membrane ◽  
Host Cell ◽  
Acyl Chain ◽  
Mass Spectrometry Analysis ◽  
Bacterial Invasion ◽  
Fatty Acyl Chain ◽  
Membrane Domain ◽  
Host Cell Membrane ◽  
Plasma Membrane Domain

AbstractThe opportunistic pathogen Pseudomonas aeruginosa has gained precedence over the years due to its ability to develop resistance to existing antibiotics, thereby necessitating alternative strategies to understand and combat the bacterium. Our previous work identified the interaction between the bacterial lectin LecA and its host cell glycosphingolipid receptor globotriaosylceramide (Gb3) as a crucial step for the engulfment of P. aeruginosa via the lipid zipper mechanism. In this study, we define the LecA-associated host cell membrane domain by pull-down and mass spectrometry analysis. We unraveled a predilection of LecA for binding to saturated, long fatty acyl chain-containing Gb3 species in the extracellular membrane leaflet and an induction of dynamic phosphatidylinositol (3,4,5)-trisphosphate (PIP3) clusters at the intracellular leaflet co-localizing with sites of LecA binding. We found flotillins and the GPI-anchored protein CD59 not only to be an integral part of the LecA-interacting membrane domain, but also majorly influencing bacterial invasion as depletion of either of these host cell proteins resulted in about 50% reduced invasiveness of the P. aeruginosa strain PAO1. In summary, we report that the LecA-Gb3 interaction at the extracellular leaflet induces the formation of a plasma membrane domain enriched in saturated Gb3 species, CD59, PIP3 and flotillin thereby facilitating efficient uptake of PAO1.

Structural preferences for the double bond position in some unsaturated 3,3-diphenylpyrrolidines

1970 ◽  
Vol 48 (23) ◽  
pp. 3742-3745 ◽  
Author(s):  
M. M. A. Hassan ◽  
A. F. Casy
Keyword(s):  
Double Bond ◽  
Methyl Iodide ◽  
Quaternary Salt ◽  
Double Bond Position ◽  
Magnesium Bromide ◽  
Free Base ◽  
Spectroscopic Evidence ◽  
Structural Preferences ◽  
Ethyl Magnesium Bromide ◽  
Sole Product

The reaction between 3,3-diphenyl-3-cyano-1-methylpropyl isocyanate and ethyl magnesium bromide leads to 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline rather than the isomeric 2-ethylidenepyrrolidine. The protonated N-methyl analogue (identical with a major metabolite of methadone) retains the 1-pyrroline structure, but the free base is a cis-trans mixture of the corresponding 2-ethylidenepyrrolidines; the cis Me/Ph isomer preponderates and is the sole product (obtained as a quaternary salt) when the mixture is treated with methyl iodide. 5-Methyl-2-methylene-3,3-diphenylpyrrolidine, a lower homologue of the methadone metabolite, isomerizes to a 1-pyrroline derivative when protonated or methylated. All structural conclusions are based on i.r. and p.m.r. spectroscopic evidence.

High resolution ion mobility-mass spectrometry for separation and identification of isomeric lipids

The Analyst ◽  
2015 ◽  
Vol 140 (20) ◽  
pp. 6904-6911 ◽  
Author(s):  
M. Groessl ◽  
S. Graf ◽  
R. Knochenmuss
Keyword(s):  
Mass Spectrometry ◽  
Double Bond ◽  
High Resolution ◽  
Ion Mobility ◽  
Biological Samples ◽  
Drift Tube ◽  
Acyl Chain ◽  
Ion Mobility Mass Spectrometry

Separation and identification of isomeric species is a major challenge in lipidomics. Herein, we demonstrate that lipid isomers that differ only in position of the acyl chain, position of the double bond or double bond geometry can be distinguished using drift-tube ion mobility-mass spectrometry, even in complex biological samples.

scholarly journals Interplay of Unsaturated Phospholipids and Cholesterol in Membranes: Effect of the Double-Bond Position

2008 ◽  
Vol 95 (7) ◽  
pp. 3295-3305 ◽  
Author(s):  
Hector Martinez-Seara ◽  
Tomasz Róg ◽  
Marta Pasenkiewicz-Gierula ◽  
Ilpo Vattulainen ◽  
Mikko Karttunen ◽  
...  
Keyword(s):  
Double Bond ◽  
Double Bond Position

scholarly journals TAMI-55. THE EVOLUTIONARY ENIGMA OF FATTY ACID DESATURATION IN GLIOBLASTOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii225-ii225
Author(s):  
Nicole Oatman ◽  
Julie Reisz ◽  
Angelo D’Alessandro ◽  
Biplab Dasgupta
Keyword(s):  
Fatty Acid ◽  
Double Bond ◽  
Acyl Chain ◽  
Enzymatic Reaction ◽  
Monounsaturated Fatty Acids ◽  
Fatty Acid Desaturation ◽  
Dual Function ◽  
Storage Lipids ◽  
Essential Components ◽  
Unexpected Findings

Abstract Fatty acid desaturation is an enzymatic reaction in which a double bond is introduced into an acyl chain. Of the four functionally distinct desaturase subfamilies, the First Desaturase Family of enzymes introduce the first double bond into a saturated fatty acid, resulting in the synthesis of monounsaturated fatty acids (MUFA). MUFA are essential components of membrane and storage lipids and exert a profound influence on the fluidity of biological membranes. A disequilibrium in saturated to unsaturated fatty acid ratio alters cell growth, differentiation and response to external stimuli, and thus affects a range of pathologies including cancer. The most abundant and key First Desaturase Family enzyme is the delta 9 desaturate called Stearoyl Co-A Desaturase (SCD and SCD5 in humans, and SCD1-4 in mice). SCD desaturates Stearoyl-CoA (C18) and palmitoyl-CoA (C16) to oleoyl-CoA (C18:1) and palmitoyl-CoA (C16:1), respectively. Besides SCD, the only known First Desaturase in mammals with dual function is FADS2 which desaturates palmitate to Sapienate (C16:1, a positional isomer of palmitoleate) in skin cells. A recent study showed that some cancer cells can use FADS2 to bypass the SCD reaction. SCD and SCD5 are by far the most abundant desaturases expressed in the human brain. We made an unexpected discovery that SCD undergoes monoallelic codeletion with PTEN on chromosome 10, and is also highly methylated in glioblastoma (GBM). More surprisingly, all GBM cell lines with SCD codeletion/methylation (that expressed very little SCD protein) are completely resistant to SCD/SCD5 inhibition, yet their phospholipids contained abundant oleic acid. It is unknown if GBMs bypassed SCD, but retained the delta 9 desaturation reaction through a novel enzymatic activity. Our targeted and untargeted metabolomics studies revealed unexpected findings that cannot be explained by conventional wisdom, and may lead to identification of novel lipogenic targets in GBM.

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