scholarly journals The Effect of Highly Hydroxylated Fullerenol C60(OH)36on Human Erythrocyte Membrane Organization

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Jacek Grebowski ◽  
Anita Krokosz
Keyword(s):  
Membrane Proteins ◽  
Membrane Fluidity ◽  
Erythrocyte Membrane ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Erythrocyte Membranes ◽  
Resonance Spectroscopy ◽  
Protein Protein Interactions ◽  
Hydrophobic Region ◽  
Sh Groups

The mechanism of the interaction of highly hydroxylated fullerenol C60(OH)36with erythrocyte membranes was studied by electron spin resonance spectroscopy (ESR) of stearic acid derivatives labeled with a nitroxyl radical at C-12 or C-16 and with a nitroxyl derivative of maleimide covalently attached to sulfhydryl groups of membrane proteins. A significant increase in membrane fluidity in the hydrophobic region of the lipid bilayer was observed for 12-doxylstearic acid at fullerenol concentrations of 100 mg/L or 150 mg/L, while for 16-doxylstearic acid significant increase in fluidity was only observed at 150 mg/L. Fullerenol at 100 mg/L or 150 mg/L caused conformational changes in membrane proteins, expressed as an increase in thehw/hsparameter, when fullerenol was added before the maleimide spin label (MSL) to the membrane suspension. The increase of thehw/hsparameter may be caused by changes in lipid-protein or protein-protein interactions which increase the mobility of the MSL label and as a result increase the membrane fluidity. Incubation of the membranes with the MSL before the addition of fullerenol blocked the available membrane protein –SH groups and minimized the interaction of fullerenol with them. This confirms that fullerenol interacts with erythrocyte membrane proteins via available protein –SH groups.

Structural alterations of erythrocyte membrane components induced by exhaustive exercise

2008 ◽  
Vol 33 (6) ◽  
pp. 1223-1231 ◽  
Author(s):  
Joanna Brzeszczynska ◽  
Anna Pieniazek ◽  
Lukasz Gwozdzinski ◽  
Krzysztof Gwozdzinski ◽  
Anna Jegier
Keyword(s):  
Lipid Peroxidation ◽  
Membrane Proteins ◽  
Membrane Fluidity ◽  
Erythrocyte Membrane ◽  
Conformational Changes ◽  
Membrane Dynamics ◽  
Resonance Spectroscopy ◽  
Reducing Ability ◽  
Exercise Induced ◽  
Membrane Components

Physical exercise was used as a model of the physiological modulator of free radical production to examine the effects of exercise-induced oxidative modifications on the physico-biochemical properties of erythrocyte membrane. The aim of our work was to investigate conformational changes of erythrocyte membrane proteins, membrane fluidity, and membrane susceptibility to disintegration. Venous blood was taken before, immediately after, and 1 h after an exhaustive incremental cycling test (30 W·min–1ramp), performed by 11 healthy untrained males on balanced diets (mean age, 22 ± 2 years; mean body mass index, 25 ± 4.5 kg·m–2). In response to this exercise, individual maximum heart rate was 195 ± 12 beats·min–1and maximum wattage was 292 ± 27 W. Electron paramagnetic resonance spectroscopy was used to investigate alterations in membrane proteins and membrane dynamics, and to measure production of radical species. The reducing potential of plasma (RPP) was measured using the reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the ferric-reducing ability of plasma. Exercise induced decreases in erythrocyte membrane fluidity in the polar region (p < 0.0001) and alterations in the conformational state of membrane proteins (p < 0.05). An increase in RPP was observed immediately after exercise (p < 0.001), with a further increase 1 h postexercise (p < 0.0001). Supporting measurements of lipid peroxidation showed an increase in thiobarbituric acid reactive substances immediately after exercise (p < 0.05) and at 1 h of recovery (p < 0.001); however, free radicals were not detected. Results indicate the existence of early postexercise mild oxidative stress after single-exercise performance, which induced structural changes in erythrocyte membrane components (protein aggregation) and in the membrane organization (lipids rigidization) that followed lipid peroxidation but did not lead to cellular hemolysis.

scholarly journals Domains of alpha-SNAP required for the stimulation of exocytosis and for N-ethylmalemide-sensitive fusion protein (NSF) binding and activation.

1996 ◽  
Vol 7 (5) ◽  
pp. 693-701 ◽  
Author(s):  
R J Barnard ◽  
A Morgan ◽  
R D Burgoyne
Keyword(s):  
Membrane Proteins ◽  
Fusion Protein ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Atp Hydrolysis ◽  
Coiled Coil ◽  
Protein Protein Interactions ◽  
Permeabilized Cells ◽  
C Terminus ◽  
Adrenal Chromaffin

The binding of alpha-SNAP to the membrane proteins syntaxin, SNAP-25, and synaptobrevin leads to the recruitment of the N-ethylmaleimide-sensitive fusion protein (NSF). ATP hydrolysis by NSF has been suggested to drive conformational changes in one or more of these membrane proteins that are essential for regulated exocytosis. Functional evidence for a role of alpha-SNAP in exocytosis in adrenal chromaffin cells comes from the ability of this protein to stimulate Ca(2+)-dependent exocytosis in digitonin-permeabilized cells. Here we examine the effect of a series of deletion mutants of alpha-SNAP on exocytosis, and on the ability of alpha-SNAP to interact with NSF, to define essential domains involved in protein-protein interactions in exocytosis. Deletion of extreme N- or C-terminal regions of alpha-SNAP produced proteins unable to bind to syntaxin or to stimulate exocytosis, suggesting that these domains participate in essential interactions. Deletion of C-terminal residues abolished the ability of alpha-SNAP to bind NSF. In contrast, deletion of up to 120 N-terminal residues did not prevent the binding of NSF to immobilized alpha-SNAP and such mutants were also able to stimulate the ATPase activity of NSF. These results suggest that the C-terminus, but not the N-terminus, of alpha-SNAP is crucial for interactions with NSF. The involvement of the C-terminus of alpha-SNAP, which contains a predicted coiled-coil domain, in the binding of both syntaxin and NSF would place the latter two proteins in proximity in a ternary complex whereupon the energy derived from ATP hydrolysis by NSF could induce a conformational change in syntaxin required for exocytosis to proceed.

The mobility and reactivity of maleimide-binding proteins in the rat erythrocyte membrane. Effects of dietary zinc deficiency and incubation with zinc in vitro

1988 ◽  
Vol 66 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Stan J. Kubow ◽  
William J. Bettger
Keyword(s):  
Membrane Proteins ◽  
Erythrocyte Membrane ◽  
Zinc Deficiency ◽  
Binding Proteins ◽  
Thermal Sensitivity ◽  
Erythrocyte Membranes ◽  
Resonance Spectroscopy ◽  
Dietary Zinc ◽  
Membrane Effects

Erythrocyte ghosts, prepared from rats fed zinc-deficient diets, were analyzed for the mobility of membrane proteins by electron spin resonance spectroscopy of the sulfhydryl-binding spin probe, 4-maleimido-2,2,6,6-tetramethylpiperidine-N-oxyl. Compared with erythrocyte membranes from rats fed zinc-adequate diets ad libitum or pair-fed, erythrocyte membranes from zinc-deficient rats had a significantly increased ratio of weakly immobilized to strongly immobilized probe-binding proteins. This suggests that dietary zinc deficiency causes a conformational change in erythrocyte membrane proteins. Dietary zinc deficiency did not significantly affect N-ethylmaleimide (NEM)-induced thermal sensitivity or NEM-induced mechanical fragility in rat erythrocytes; however, the addition of zinc in vitro to red cells significantly inhibits NEM-induced mechanical fragility.

scholarly journals Insights into the Role of Membrane Lipids in the Structure, Function and Regulation of Integral Membrane Proteins

2021 ◽  
Vol 22 (16) ◽  
pp. 9026
Author(s):  
Kenta Renard ◽  
Bernadette Byrne
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Membrane Lipids ◽  
Protein Protein Interactions ◽  
Technological Advances ◽  
Highly Hydrophobic ◽  
Dynamics Simulations ◽  
And Function

Membrane proteins exist within the highly hydrophobic membranes surrounding cells and organelles, playing key roles in cellular function. It is becoming increasingly clear that the membrane does not just act as an appropriate environment for these proteins, but that the lipids that make up these membranes are essential for membrane protein structure and function. Recent technological advances in cryogenic electron microscopy and in advanced mass spectrometry methods, as well as the development of alternative membrane mimetic systems, have allowed experimental study of membrane protein–lipid complexes. These have been complemented by computational approaches, exploiting the ability of Molecular Dynamics simulations to allow exploration of membrane protein conformational changes in membranes with a defined lipid content. These studies have revealed the importance of lipids in stabilising the oligomeric forms of membrane proteins, mediating protein–protein interactions, maintaining a specific conformational state of a membrane protein and activity. Here we review some of the key recent advances in the field of membrane protein–lipid studies, with major emphasis on respiratory complexes, transporters, channels and G-protein coupled receptors.

scholarly journals POT1-TPP1 differentially regulates telomerase via POT1 His266 and as a function of single-stranded telomere DNA length

2019 ◽  
Vol 116 (47) ◽  
pp. 23527-23533 ◽  
Author(s):  
Mengyuan Xu ◽  
Janna Kiselar ◽  
Tawna L. Whited ◽  
Wilnelly Hernandez-Sanchez ◽  
Derek J. Taylor
Keyword(s):  
Conformational Changes ◽  
Protein Interactions ◽  
Environmental Changes ◽  
Lymphocytic Leukemia ◽  
Protein Protein Interactions ◽  
Cellular Environment ◽  
Multiple Protein ◽  
Linear Chromosomes ◽  
Hydroxyl Radical Footprinting ◽  
Regulate Telomere Length

Telomeres cap the ends of linear chromosomes and terminate in a single-stranded DNA (ssDNA) overhang recognized by POT1-TPP1 heterodimers to help regulate telomere length homeostasis. Here hydroxyl radical footprinting coupled with mass spectrometry was employed to probe protein–protein interactions and conformational changes involved in the assembly of telomere ssDNA substrates of differing lengths bound by POT1-TPP1 heterodimers. Our data identified environmental changes surrounding residue histidine 266 of POT1 that were dependent on telomere ssDNA substrate length. We further determined that the chronic lymphocytic leukemia-associated H266L substitution significantly reduced POT1-TPP1 binding to short ssDNA substrates; however, it only moderately impaired the heterodimer binding to long ssDNA substrates containing multiple protein binding sites. Additionally, we identified a telomerase inhibitory role when several native POT1-TPP1 proteins coat physiologically relevant lengths of telomere ssDNA. This POT1-TPP1 complex-mediated inhibition of telomerase is abrogated in the context of the POT1 H266L mutation, which leads to telomere overextension in a malignant cellular environment.

Quantitative analysis of the interactions between HIV-1 integrase and retroviral reverse transcriptases

2008 ◽  
Vol 412 (1) ◽  
pp. 163-170 ◽  
Author(s):  
Alon Herschhorn ◽  
Iris Oz-Gleenberg ◽  
Amnon Hizi
Keyword(s):  
Conformational Changes ◽  
Protein Interactions ◽  
Molecular Mechanisms ◽  
Reaction Model ◽  
Protein Protein Interactions ◽  
Common Site ◽  
Leukaemia Virus ◽  
Reverse Transcriptases ◽  
Interaction Kinetics ◽  
Hiv 1

The RT (reverse transcriptase) of HIV-1 interacts with HIV-1 IN (integrase) and inhibits its enzymatic activities. However, the molecular mechanisms underling these interactions are not well understood. In order to study these mechanisms, we have analysed the interactions of HIV-1 IN with HIV-1 RT and with two other related RTs: those of HIV-2 and MLV (murine-leukaemia virus). All three RTs inhibited HIV-1 IN, albeit to a different extent, suggesting a common site of binding that could be slightly modified for each one of the studied RTs. Using surface plasmon resonance technology, which monitors direct protein–protein interactions, we performed kinetic analyses of the binding of HIV-1 IN to these three RTs and observed interesting binding patterns. The interaction of HIV-1 RT with HIV-1 IN was unique and followed a two-state reaction model. According to this model, the initial IN–RT complex formation was followed by a conformational change in the complex that led to an elevation of the total affinity between these two proteins. In contrast, HIV-2 and MLV RTs interacted with IN in a simple bi-molecular manner, without any apparent secondary conformational changes. Interestingly, HIV-1 and HIV-2 RTs were the most efficient inhibitors of HIV-1 IN activity, whereas HIV-1 and MLV RTs showed the highest affinity towards HIV-1 IN. These modes of direct protein interactions, along with the apparent rate constants calculated and the correlations of the interaction kinetics with the capacity of the RTs to inhibit IN activities, are all discussed.

scholarly journals Molecular dynamics shows complex interplay and long-range effects of post-translational modifications in yeast protein interactions

2021 ◽  
Vol 17 (5) ◽  
pp. e1008988
Author(s):  
Nikolina ŠoŠtarić ◽  
Vera van Noort
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Protein Structures ◽  
Cellular Protein ◽  
Free Energy Calculations ◽  
Protein Protein Interactions ◽  
Post Translational Modifications ◽  
Protein Properties ◽  
Dynamics Simulations

Post-translational modifications (PTMs) play a vital, yet often overlooked role in the living cells through modulation of protein properties, such as localization and affinity towards their interactors, thereby enabling quick adaptation to changing environmental conditions. We have previously benchmarked a computational framework for the prediction of PTMs’ effects on the stability of protein-protein interactions, which has molecular dynamics simulations followed by free energy calculations at its core. In the present work, we apply this framework to publicly available data on Saccharomyces cerevisiae protein structures and PTM sites, identified in both normal and stress conditions. We predict proteome-wide effects of acetylations and phosphorylations on protein-protein interactions and find that acetylations more frequently have locally stabilizing roles in protein interactions, while the opposite is true for phosphorylations. However, the overall impact of PTMs on protein-protein interactions is more complex than a simple sum of local changes caused by the introduction of PTMs and adds to our understanding of PTM cross-talk. We further use the obtained data to calculate the conformational changes brought about by PTMs. Finally, conservation of the analyzed PTM residues in orthologues shows that some predictions for yeast proteins will be mirrored to other organisms, including human. This work, therefore, contributes to our overall understanding of the modulation of the cellular protein interaction networks in yeast and beyond.

scholarly journals Mitochondria: Regulators of Cell Death and Survival

2002 ◽  
Vol 2 ◽  
pp. 1569-1578 ◽  
Author(s):  
David J. Granville ◽  
Roberta A. Gottlieb
Keyword(s):  
Cell Death ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Apoptotic Cell ◽  
Critical Role ◽  
Death Process ◽  
Protein Protein Interactions ◽  
Ionic Changes ◽  
A Cell ◽  
Cyt C

The past 5 years has seen an intense surge in research devoted toward understanding the critical role of mitochondria in the regulation of cell death. Apoptosis can be initiated by a wide array of stimuli, inducing multiple signaling pathways that, for the most part, converge at the mitochondrion. Although classically considered the powerhouses of the cell, it is now understood that mitochondria are also “gatekeepers” that ultimately determine the fate of the cell. The mitochondrial decision as to whether a cell lives or dies is complex, involving protein-protein interactions, ionic changes, reactive oxygen species, and other mechanisms that require further elucidation. Once the death process is initiated, mitochondria undergo conformational changes, resulting in the release of cytochrome c (cyt c), caspases, endonucleases, and other factors leading to the onset and execution of apoptosis. The present review attempts to outline the complex milieu of events regulating the mitochondrial commitment to and processes involved in the implementation of the executioner phase of apoptotic cell death.

scholarly journals Novel pathogenic XK mutations in McLeod syndrome and interaction between XK protein and chorein

2019 ◽  
Vol 5 (3) ◽  
pp. e328 ◽  
Author(s):  
Yuka Urata ◽  
Masayuki Nakamura ◽  
Natsuki Sasaki ◽  
Nari Shiokawa ◽  
Yoshiaki Nishida ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Erythrocyte Membrane ◽  
Molecular Analysis ◽  
Cultured Cells ◽  
Immunoblot Analysis ◽  
Erythrocyte Membranes ◽  
Onset Age ◽  
Novel Mutations ◽  
Erythrocyte Membrane Proteins ◽  
Normal Controls

ObjectiveTo identify XK pathologic mutations in 6 patients with suspected McLeod syndrome (MLS) and a possible interaction between the chorea-acanthocytosis (ChAc)- and MLS-responsible proteins: chorein and XK protein.MethodsErythrocyte membrane proteins from patients with suspected MLS and patients with ChAc, ChAc mutant carriers, and normal controls were analyzed by XK and chorein immunoblotting. We performed mutation analysis and XK immunoblotting to molecularly diagnose the patients with suspected MLS. Lysates of cultured cells were co-immunoprecipitated with anti-XK and anti-chorein antibodies.ResultsAll suspected MLS cases were molecularly diagnosed with MLS, and novel mutations were identified. The average onset age was 46.8 ± 8 years, which was older than that of the patients with ChAc. The immunoblot analysis revealed remarkably reduced chorein immunoreactivity in all patients with MLS. The immunoprecipitation analysis indicated a direct or indirect chorein-XK interaction.ConclusionsIn this study, XK pathogenic mutations were identified in all 6 MLS cases, including novel mutations. Chorein immunoreactions were significantly reduced in MLS erythrocyte membranes. In addition, we demonstrated a possible interaction between the chorein and XK protein via molecular analysis. The reduction in chorein expression is similar to that between Kell antigens and XK protein, although the chorein-XK interaction is a possibly noncovalent binding unlike the covalent Kell-XK complex. Our results suggest that reduced chorein levels following lack of XK protein are possibly associated with molecular pathogenesis in MLS.

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