Membrane lipids are key modulators of the endocannabinoid-hydrolase FAAH

2014 ◽  
Vol 457 (3) ◽  
pp. 463-472 ◽  
Author(s):  
Enrico Dainese ◽  
Gianni De Fabritiis ◽  
Annalaura Sabatucci ◽  
Sergio Oddi ◽  
Clotilde Beatrice Angelucci ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Molecular Dynamic ◽  
Binding Affinity ◽  
Free Cholesterol ◽  
Membrane Lipids ◽  
Membrane Binding ◽  
Dimeric Structure ◽  
Dynamic Studies

The dimeric structure of FAAH is stabilized by the membrane. The membrane-binding affinity of FAAH is relevant for subcellular localization. Free cholesterol within the membrane increases the activity of the enzyme. Molecular dynamic studies suggest that cholesterol increases substrate accessibility.

scholarly journals Impact of Membrane Lipids on UapA and AzgA Transporter Subcellular Localization and Activity in Aspergillus nidulans

2021 ◽  
Vol 7 (7) ◽  
pp. 514
Author(s):  
Mariangela Dionysopoulou ◽  
George Diallinas
Keyword(s):  
Plasma Membrane ◽  
Subcellular Localization ◽  
Aspergillus Nidulans ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Lipid Biosynthesis ◽  
Transport Kinetics ◽  
Negative Effect ◽  
And Function

Recent biochemical and biophysical evidence have established that membrane lipids, namely phospholipids, sphingolipids and sterols, are critical for the function of eukaryotic plasma membrane transporters. Here, we study the effect of selected membrane lipid biosynthesis mutations and of the ergosterol-related antifungal itraconazole on the subcellular localization, stability and transport kinetics of two well-studied purine transporters, UapA and AzgA, in Aspergillus nidulans. We show that genetic reduction in biosynthesis of ergosterol, sphingolipids or phosphoinositides arrest A. nidulans growth after germling formation, but solely blocks in early steps of ergosterol (Erg11) or sphingolipid (BasA) synthesis have a negative effect on plasma membrane (PM) localization and stability of transporters before growth arrest. Surprisingly, the fraction of UapA or AzgA that reaches the PM in lipid biosynthesis mutants is shown to conserve normal apparent transport kinetics. We further show that turnover of UapA, which is the transporter mostly sensitive to membrane lipid content modification, occurs during its trafficking and by enhanced endocytosis, and is partly dependent on autophagy and Hect-type HulARsp5 ubiquitination. Our results point out that the role of specific membrane lipids on transporter biogenesis and function in vivo is complex, combinatorial and transporter-dependent.

scholarly journals Membrane Translocation of 15-Lipoxygenase in Hematopoietic Cells Is Calcium-Dependent and Activates the Oxygenase Activity of the Enzyme

Blood ◽  
1998 ◽  
Vol 91 (1) ◽  
pp. 64-74 ◽  
Author(s):  
Roland Brinckmann ◽  
Kerstin Schnurr ◽  
Dagmar Heydeck ◽  
Thomas Rosenbach ◽  
Gerhard Kolde ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Immunoelectron Microscopy ◽  
Membrane Lipids ◽  
Membrane Binding ◽  
Hematopoietic Cells ◽  
Cell Fractionation ◽  
Calcium Dependent ◽  
Oxygenase Activity ◽  
Lipoxygenase Products

Abstract Mammalian 15-lipoxygenases, which have been implicated in the differentiation of hematopoietic cells are commonly regarded as cytosolic enzymes. Studying the interaction of the purified rabbit reticulocyte 15-lipoxygenase with various types of biomembranes, we found that the enzyme binds to biomembranes when calcium is present in the incubation mixture. Under these conditions, an oxidation of the membrane lipids was observed. The membrane binding was reversible and led to an increase in the fatty acid oxygenase activity of the enzyme. To find out whether such a membrane binding also occurs in vivo, we investigated the intracellular localization of the enzyme in stimulated and resting hematopoietic cells by immunoelectron microscopy, cell fractionation studies and activity assays. In rabbit reticulocytes, the 15-lipoxygenase was localized in the cytosol, but also bound to intracellular membranes. This membrane binding was also reversible and the detection of specific lipoxygenase products in the membrane lipids indicated the in vivo activity of the enzyme on endogenous substrates. Immunoelectron microscopy showed that in interleukin-4 –treated monocytes, the 15-lipoxygenase was localized in the cytosol, but also at the inner side of the plasma membrane and at the cytosolic side of intracellular vesicles. Here again, cell fractionation studies confirmed the in vivo membrane binding of the enzyme. In human eosinophils, which constitutively express the 15-lipoxygenase, the membrane bound share of the enzyme was augmented when the cells were stimulated with calcium ionophore. Only under these conditions, specific lipoxygenase products were detected in the membrane lipids. These data suggest that in hematopoietic cells the cytosolic 15-lipoxygenase translocates reversibly to the cellular membranes. This translocation, which increases the fatty acid oxygenase activity of the enzyme, is calcium-dependent, but may not require a special docking protein.

scholarly journals Multiple Parameters Beyond Lipid Binding Affinity Drive Cytotoxicity of Cholesterol-Dependent Cytolysins

Toxins ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 1 ◽  
Author(s):  
Sucharit Ray ◽  
Roshan Thapa ◽  
Peter Keyel
Keyword(s):  
Cell Death ◽  
Binding Affinity ◽  
Hemolytic Activity ◽  
Mammalian Cells ◽  
Pathogenic Bacteria ◽  
Calcium Influx ◽  
Membrane Binding ◽  
Lipid Binding ◽  
Membrane Repair ◽  
Death Kinetics

The largest superfamily of bacterial virulence factors is pore-forming toxins (PFTs). PFTs are secreted by both pathogenic and non-pathogenic bacteria. PFTs sometimes kill or induce pro-pathogen signaling in mammalian cells, all primarily through plasma membrane perforation, though the parameters that determine these outcomes are unclear. Membrane binding, calcium influx, pore size, and membrane repair are factors that influence PFT cytotoxicity. To test the contribution of membrane binding to cytotoxicity and repair, we compared the closely related, similarly-sized PFTs Perfringolysin O (PFO) from Clostridium perfringens and Streptolysin O (SLO) from Streptococcus pyogenes. Cell death kinetics for PFO and SLO were different because PFO increased in cytotoxicity over time. We introduced known L3 loop mutations that swap binding affinity between toxins and measured hemolytic activity, nucleated cell death kinetics and membrane repair using viability assays, and live cell imaging. Altered hemolytic activity was directly proportional to toxin binding affinity. In contrast, L3 loop alterations reduced nucleated cell death, and they had limited effects on cytotoxicity kinetics and membrane repair. This suggests other toxin structural features, like oligomerization, drives these parameters. Overall, these findings suggest that repair mechanisms and toxin oligomerization add constraints beyond membrane binding on toxin evolution and activity against nucleated cells.

scholarly journals Molecular Dynamic Studies of the Complex Polyethylenimine and Glucose Oxidase

2016 ◽  
Vol 17 (11) ◽  
pp. 1796 ◽  
Author(s):  
Beata Szefler ◽  
Mircea Diudea ◽  
Mihai Putz ◽  
Ireneusz Grudzinski
Keyword(s):  
Glucose Oxidase ◽  
Molecular Dynamic ◽  
Dynamic Studies

Molecular dynamic studies of the solubility of sodium chloride: fast calculations using seed crystalline cluster probe

2015 ◽  
Vol 113 (21) ◽  
pp. 3176-3181 ◽  
Author(s):  
Heather Wiebe ◽  
Johan Louwersheimer ◽  
Noham Weinberg
Keyword(s):  
Sodium Chloride ◽  
Molecular Dynamic ◽  
Dynamic Studies
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