Search results for "Membrane Lipids"
showing 10 items of 80 documents
Neptuniibacter caesariensis gen. nov., sp. nov., a novel marine genome-sequenced gammaproteobacterium.
2007
7 pages, 1 figure, 1 table
Inverse Conformational Selection in Lipid–Protein Binding
2021
International audience; Interest in lipid interactions with proteins and other biomolecules is emerging not only in fundamental biochemistry but also in the field of nanobiotechnology where lipids are commonly used, for example, in carriers of mRNA vaccines. The outward-facing components of cellular membranes and lipid nanoparticles, the lipid headgroups, regulate membrane interactions with approaching substances, such as proteins, drugs, RNA, or viruses. Because lipid headgroup conformational ensembles have not been experimentally determined in physiologically relevant conditions, an essential question about their interactions with other biomolecules remains unanswered: Do headgroups excha…
A small HSP, Lo18, interacts with the cell membrane and modulates lipid physical state under heat shock conditions in a lactic acid bacterium
2005
International audience; The small heat shock proteins (sHSP) are characterized by a chaperone activity to prevent irreversible protein denaturation. This study deals with the sHSP Lo18 induced by multiple stresses in Oenococcus oeni, a lactic acid bacterium. Using in situ immunocytochemistry and cellular fractionation experiments, we demonstrated the association of Lo18 with the membrane in O. oeni cells submitted to heat shock. The same result was obtained after exposure of cells to ethanol or benzyl alcohol, agents known to have an influence on membranes. For the different stresses, the protein was located on the periphery of the cell at membrane level and was also found within the cytopl…
Gibberellic acid stimulates lipid metabolism in barley aleurone protoplasts
1991
Abstract Changes in the lipid composition of barley aleurone protoplasts following incubation in the presence or absence of gibberellic acid (GA) were studied and correlated with cell development. Analysis of neutral lipids in protoplast extracts and purified lipid bodies provide evidence for the strong effect of GA on the mobilization of storage lipids. In vivo protoplast staining with the membrane marker N -phenyl-l-naphthylamine (NPN) and phospholipid determinations of protoplast extracts show an increase in membrane lipids during protoplast incubation. GA stimulates phospholipid metabolism by increasing the synthesis of phosphatidyl ethanolamine and phosphatidyl choline, the major phosp…
Oligomerization and hemolytic properties of the C-terminal domain of pyolysin, a cholesterol-dependent cytolysin
2013
Pyolysin (PLO) belongs to the homologous family of the cholesterol- dependent cytolysins (CDCs), which bind to cell membranes containing cholesterol to form oligomeric pores of large size. The CDC monomer structure consists of 4 domains. Among these, the C-terminal domain 4 has been implicated in membrane binding of the monomer, while the subsequent processes of oligomerization and membrane insertion have primarily been assigned to other domains of the molecule. Recombinantly expressed or proteolytic fragments that span domain 4 of the CDCs streptolysin O and perfringolysin O bind to membranes but fail to oligomerize, and they inhibit the activity of the respective wild-type toxins. We repo…
ATR-FTIR spectroscopy for the routine quality control of exosome isolations
2021
Abstract Exosomes are nanosized vesicles containing specific cargos of DNA, RNA, proteins, metabolites, and intracellular and membrane lipids. Exosome isolation needs to be optimized carefully depending on the type of biofluid and tissue and the retrieved exosomes need to be characterized. The main objective of this study was to determine the feasibility of a multimodal analysis of Attenuated Total Reflectance – Fourier Transform Infrared (ATR-FTIR) spectroscopy and UPLC–QqTOF-MSMS for the development of a routine quality control tool of isolated exosomes and the rapid characterization of their lipid profiles and total protein content. Using human milk as model example, exosomes were isolat…
Membrane-insertion fragments of Bcl-xL, Bax, and Bid.
2004
Apoptosis regulators of the Bcl-2 family associate with intracellular membranes from mitochondria and the endoplasmic reticulum, where they perform their function. The activity of these proteins is related to the release of apoptogenic factors, sequestered in the mitochondria, to the cytoplasm, probably through the formation of ion and/or protein transport channels. Most of these proteins contain a C-terminal putative transmembrane (TM) fragment and a pair of hydrophobic alpha helices (alpha5-alpha6) similar to the membrane insertion fragments of the ion-channel domain of diphtheria toxin and colicins. Here, we report on the membrane-insertion properties of different segments from antiapopt…
N- and O-methylation of sphingomyelin markedly affects its membrane properties and interactions with cholesterol
2011
We have prepared palmitoyl sphingomyelin (PSM) analogs in which either the 2-NH was methylated to NMe, the 3-OH was methylated to OMe, or both were methylated simultaneously. The aim of the study was to determine how such modifications in the membrane interfacial region of the molecules affected interlipid interactions in bilayer membranes. Measuring DPH anisotropy in vesicle membranes prepared from the SM analogs, we observed that methylation decreased gel-phase stability and increased fluid phase disorder, when compared to PSM. Methylation of the 2-NH had the largest effect on gel-phase instability (T(m), was lowered by similar to 7 degrees C). Atomistic molecular dynamics simulations sho…
Stabilisation of mixed peptide/lipid complexes in selective antifungal hexapeptides
2004
AbstractThe design of antimicrobial peptides could have benefited from structural studies of known peptides having specific activity against targetmicrobes, but not toward other microorganisms. We have previously reported the identification of a series of peptides (PAF-series) activeagainst certain postharvest fungal phytopathogens, and devoid of toxicity towards E. coli and S. cerevisiae [Lo´pez-Garci´a et al. Appl.Environ. Microbiol. 68 (2002) 2453]. The peptides inhibited the conidia germination and hyphal growth. Here, we present a comparativestructural characterisation of selected PAF peptides obtained by single-amino-acid replacement, which differ in biological activity. Thepeptides w…
Double layer potential and degree of dissociation in charged lipid monolayers
2000
Abstract One of the contributions to the surface potential in charged phospholipid monolayers at air–water interfaces is the double layer potential. In this note several misconceptions found in the literature concerning the relationship between the double layer potential and the degree of dissociation of the lipid polar headgroups are critically analyzed. The deviations of the double layer potential measurements from the Gouy–Chapman theory observed by several authors are explained by taking into account the dependence of the degree of dissociation with concentration, area per lipid molecule and pH.