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Jaap Sinninghe S. Damsté - One of the best experts on this subject based on the ideXlab platform.
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New Insights Into the Polar Lipid Composition of Extremely Halo(alkali)philic Euryarchaea From Hypersaline Lakes
Frontiers Media S.A., 2019Co-Authors: Nicole J. Bale, Dimitry Y. Sorokin, Ellen C. Hopmans, Michel Koenen, Irene W. C. Rijpstra, Laura Villanueva, Hans Wienk, Jaap Sinninghe S. DamstéAbstract:We analyzed the polar membrane lipids of 13 strains of halo(alkali)philic euryarchaea from hypersaline lakes. Nine belong to the class Halobacteria, representing two functional groups: aerobic polysaccharide utilizers and sulfur-respiring anaerobes. The other four strains represent halo(alkali)philic methanogens from the class Methanomicrobia and a recently discovered class Methanonatronarchaeia. A wide range of polar lipids were detected across the 13 strains including dialkyl glycerol diethers (archaeols), membrane-spanning glycerol tetraethers and diether-based cardiolipins. The archaeols contained a range of core lipid structures, including combinations of C20 and C25 isoprenoidal alkyl chains, unsaturations, and hydroxy moieties. Several diether lipids were novel, including: (a) a phosphatidylglycerolhexose (PG-Gly) headgroup, (b) a N,N,N-trimethyl aminopentanetetrol (APT)-like lipid with a methoxy group in place of a hydroxy group on the pentanetetrol, (c) a series of polar lipids with a headgroup with elemental composition of either C12H25NO13S or C12H25NO16S2, and (d) novel cardiolipins containing a putative phosphatidylglycerolphosphate glycerophosphate (PGPGP) polar moiety. We found that the lipid distribution of the 13 strains could be generally separated into two groups, the methanogens (group) and the Halobacteria (class) based on the presence of specific core lipids. Within the methanogens, adaption to a high or more moderate salt concentration resulted in different ratios of glycerol dialkyl glycerol tetraethers (GDGTs) to archaeol. The methanogen Methanosalsum natronophilum AME2T had the most complex diether lipid composition of any of the 13 strains, including hydroxy archaeol and macrocyclic archaeol which we surmise is an order-specific membrane adaption. The zwitterionic Headgroups APT and APT-Me were detected only in the Methanomicrobiales member Methanocalculus alkaliphilus AMF2T which also contained the highest level of unsaturated lipids. Only alkaliphilic members of the Natrialbales order contained PGPGP cardiolipins and the PG-Gly headgroup. The four analyzed neutrophilic members of the Halobacteria were characterized by the presence of sulfur-containing Headgroups and glycolipids. The presence of cardiolipins with one or more i-C25 alkyl chains, generally termed extended archaeol (EXT-AR), in one of the Methanonatronarchaeia strains was unexpected as only one other order of methanogenic archaea has been reported to produce EXT-AR. We examined this further by looking into the genomic potential of various archaea to produce EXT-AR
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Table_1_New Insights Into the Polar Lipid Composition of Extremely Halo(alkali)philic Euryarchaea From Hypersaline Lakes.docx
2019Co-Authors: Nicole J. Bale, Dimitry Y. Sorokin, Ellen C. Hopmans, Michel Koenen, Irene W. C. Rijpstra, Laura Villanueva, Hans Wienk, Jaap Sinninghe S. DamstéAbstract:We analyzed the polar membrane lipids of 13 strains of halo(alkali)philic euryarchaea from hypersaline lakes. Nine belong to the class Halobacteria, representing two functional groups: aerobic polysaccharide utilizers and sulfur-respiring anaerobes. The other four strains represent halo(alkali)philic methanogens from the class Methanomicrobia and a recently discovered class Methanonatronarchaeia. A wide range of polar lipids were detected across the 13 strains including dialkyl glycerol diethers (archaeols), membrane-spanning glycerol tetraethers and diether-based cardiolipins. The archaeols contained a range of core lipid structures, including combinations of C20 and C25 isoprenoidal alkyl chains, unsaturations, and hydroxy moieties. Several diether lipids were novel, including: (a) a phosphatidylglycerolhexose (PG-Gly) headgroup, (b) a N,N,N-trimethyl aminopentanetetrol (APT)-like lipid with a methoxy group in place of a hydroxy group on the pentanetetrol, (c) a series of polar lipids with a headgroup with elemental composition of either C12H25NO13S or C12H25NO16S2, and (d) novel cardiolipins containing a putative phosphatidylglycerolphosphate glycerophosphate (PGPGP) polar moiety. We found that the lipid distribution of the 13 strains could be generally separated into two groups, the methanogens (group) and the Halobacteria (class) based on the presence of specific core lipids. Within the methanogens, adaption to a high or more moderate salt concentration resulted in different ratios of glycerol dialkyl glycerol tetraethers (GDGTs) to archaeol. The methanogen Methanosalsum natronophilum AME2T had the most complex diether lipid composition of any of the 13 strains, including hydroxy archaeol and macrocyclic archaeol which we surmise is an order-specific membrane adaption. The zwitterionic Headgroups APT and APT-Me were detected only in the Methanomicrobiales member Methanocalculus alkaliphilus AMF2T which also contained the highest level of unsaturated lipids. Only alkaliphilic members of the Natrialbales order contained PGPGP cardiolipins and the PG-Gly headgroup. The four analyzed neutrophilic members of the Halobacteria were characterized by the presence of sulfur-containing Headgroups and glycolipids. The presence of cardiolipins with one or more i-C25 alkyl chains, generally termed extended archaeol (EXT-AR), in one of the Methanonatronarchaeia strains was unexpected as only one other order of methanogenic archaea has been reported to produce EXT-AR. We examined this further by looking into the genomic potential of various archaea to produce EXT-AR.
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compound specific stable isotope analysis of nitrogen containing intact polar lipids
Rapid Communications in Mass Spectrometry, 2015Co-Authors: Elisabeth Svensson, Stefan Schouten, Axel Stam, Jack J Middelburg, Jaap Sinninghe S. DamstéAbstract:RATIONALE: Compound-specific isotope analysis (CSIA) of nitrogen in amino acids has proven a valuable tool in manyfields (e.g. ecology). Several intact polar lipids (IPLs) also contain nitrogen, and their nitrogen isotope ratios have thepotential to elucidate food-web interactions or metabolic pathways. Here we have developed novel methodology forthe determination of d15N values of nitrogen-containing Headgroups of IPLs using gas chromatography coupled withisotope-ratio mass spectrometry. METHODS: Intact polar lipids with nitrogen-containing Headgroups were hydrolyzed and the resulting compoundswere derivatized by (1) acetylation with pivaloyl chloride for compounds with amine and hydroxyl groups or(2) esterification using acidified 2-propanol followed by acetylation with pivaloyl chloride for compounds withboth carboxyl and amine groups. The d15N values of the derivatives were subsequently determined using gaschromatography/combustion/isotope-ratio mass spectrometry. RESULTS: Intact polar lipids with ethanolamine and amino acid Headgroups, such as phosphatidylethanolamine andphosphatidylserine, were successfully released from the IPLs and derivatized. Using commercially available purecompounds it was established that d15N values of ethanolamine and glycine were not statistically different from theoffline-determined values. Application of the technique to microbial cultures and a microbial mat showed that themethod works well for the release and derivatization of the headgroup of phosphatidylethanolamine, a common IPLin bacteria. CONCLUSIONS: A method to enable CSIA of nitrogen of selected IPLs has been developed. The method is suitable formeasuring natural stable nitrogen isotope ratios in microbial lipids, in particular phosphatidylethanolamine, and will beespecially useful for tracing the fate of nitrogen in deliberate tracer experiments. Copyright © 2015 JohnWiley & Sons, Ltd.
Avinash Bajaj - One of the best experts on this subject based on the ideXlab platform.
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nature of the charged headgroup determines the fusogenic potential and membrane properties of lithocholic acid phospholipids
Journal of Physical Chemistry B, 2014Co-Authors: Priyanshu Bhargava, Manish Singh, Vedagopuram Sreekanth, Avinash BajajAbstract:Phospholipids play a crucial role in many cellular processes ranging from selective membrane permeability, to membrane fission and fusion, to cellular signaling. Headgroups of phospholipids determine the membrane properties and fusogenicity of these lipids with target cell membranes. We studied the fusogenic and membrane properties of phospholipids possessing unnatural charged Headgroups with model membranes using laurdan based membrane hydration studies, DPH based membrane fluidity, and differential scanning calorimetry. We unravel that fusogenicity, membrane hydration, and fluidity of membranes are strongly contingent on the nature of the phospholipid charged headgroup. Our studies unraveled that introduction of bulky Headgroups like dimethylamino pyridine induces maximum membrane hydration and perturbations with high fusogenicity as compared to small headgroup based phospholipids. These phospholipids also have the capability of high retention in DPPC membranes. Hydration and fluidity of these phospholi...
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Membranes of Cationic Gemini Lipids based on Cholesterol with Hydroxyl Headgroups and their Interactions with DNA and Phospholipid
The journal of physical chemistry. B, 2010Co-Authors: Joydeep Biswas, Avinash Bajaj, Santanu BhattacharyaAbstract:Two series of cholesterol-based cationic gemini lipids with and without hydroxyl functions at the Headgroups possessing different lengths of polymethylene -(CH2)(n)-] (n = 3, 4, 5, 6, 12) spacer have been synthesized. Each gemini lipid formed stable suspension in water. The suspensions of these gemini lipids in water were investigated using transmission electron microscopy, dynamic light scattering, zeta potential measurements and X-ray diffraction to characterize the nature of the individual aggregates formed therein. The aggregation properties of these gemini lipids in water were found to strongly depend upon the length of the spacer and the presence of hydroxyl group at the headgroup region. Lipoplex formation (DNA binding) and the release of the DNA from such lipoplexes were performed to understand the nature of interactions that prevail between these cationic cholesterol aggregates and duplex DNA. The interactions between such gemini lipids and DNA depend both on the presence of OH on the Headgroups and the spacer length between the Headgroups. Finally, we studied the effect of incorporation of each cationic gemini lipid into dipalmitoyl phosphatidylcholine vesicles using differential scanning calorimetry. The properties of the resulting mixed membranes were found again to depend upon the nature of the headgroup and the spacer chain length.
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membrane forming properties of gemini lipids possessing aromatic backbone between the hydrocarbon chains and the cationic headgroup
Journal of Physical Chemistry B, 2007Co-Authors: Santanu Bhattacharya, Avinash BajajAbstract:Membrane-forming properties of five new gemini cationic lipids possessing an aromatic backbone between the headgroup and hydrocarbon chains have been presented. These gemini lipids differ by the number of polymethylene units [−(CH2)n−] between the cationic ammonium −[N+(CH3)2]− Headgroups. The membrane-forming properties of these gemini lipids have been studied in detail by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), high-sensitivity differential scanning calorimetry (DSC), Paldan fluorescence studies, and UV−vis absorption spectroscopy. The electron micrographs and dynamic light scattering of their aqueous suspensions confirmed the formation of vesicular-type aggregates. The vesicle sizes and morphologies were found to depend strongly on the n-value of the spacer. Information on the thermotropic and hydration properties of the resulting vesicles was obtained from differential scanning calorimetry and temperature-dependent Paldan fluorescence studies, r...
Mathias Losche - One of the best experts on this subject based on the ideXlab platform.
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structure of functional staphylococcus aureus α hemolysin channels in tethered bilayer lipid membranes
Biophysical Journal, 2009Co-Authors: Duncan J Mcgillivray, Gintaras Valincius, Frank Heinrich, Joseph W F Robertson, David J Vanderah, Wilma Feboayala, Ilja Ignatjev, Mathias LoscheAbstract:We demonstrate a method for simultaneous structure and function determination of integral membrane proteins. Electrical impedance spectroscopy shows that Staphylococcus aureus α-hemolysin channels in membranes tethered to gold have the same properties as those formed in free-standing bilayer lipid membranes. Neutron reflectometry provides high-resolution structural information on the interaction between the channel and the disordered membrane, validating predictions based on the channel's x-ray crystal structure. The robust nature of the membrane enabled the precise localization of the protein within 1.1 A. The channel's extramembranous cap domain affects the lipid headgroup region and the alkyl chains in the outer membrane leaflet and significantly dehydrates the Headgroups. The results suggest that this technique could be used to elucidate molecular details of the association of other proteins with membranes and may provide structural information on domain organization and stimuli-responsive reorganization for transmembrane proteins in membrane mimics.
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Structural reorganization of phospholipid Headgroups upon recrystallization of an S-layer lattice
The Journal of Physical Chemistry B, 2002Co-Authors: Markus J. Weygand, Kristian Kjaer, Paul B. Howes, Barbara Wetzer, Dietmar Pum, Uwe B. Sleytr, Mathias LoscheAbstract:Structural details of the coupling of bacterial surface (S)-layers to the phospholipid, dipalmitoylphosphatidylethanolamine (DPPE), have been characterized using X-ray and neutron reflectometry. We studied the binding andrecrystallization of S-protein isolated from B. sphaericus CCM2177 at DPPE monolayers on aqueous surfaces. Particular emphasis has been put on investigations of the lipid/protein interface in a joint refinement of X-ray and neutron data which reveals alterations of the molecular-level organization of the lipid Headgroups upon protein binding and recrystallization: Peptide material interpenetrates the phospholipid Headgroups almost in its entire depth but does not affect the hydrophobic lipid acyl chains. Consistent with FTIR results, we find that the headgroup hydration is reduced by ∼40% upon peptide interpenetration. On average, the equivalent of ∼65 electrons associated with the peptide, i.e., less than one peptide side group, interacts directly with one DPPE headgroup within the surface film. This suggests that the protein attaches to specific molecular moieties within the lipid monolayer which may form a lateral pattern within the film area that reflects the properties of the monomolecular protein crystal sheet.
Mobeen Raja - One of the best experts on this subject based on the ideXlab platform.
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do small Headgroups of phosphatidylethanolamine and phosphatidic acid lead to a similar folding pattern of the k channel
The Journal of Membrane Biology, 2011Co-Authors: Mobeen RajaAbstract:Phospholipid Headgroups act as major determinants in proper folding of oligomeric membrane proteins. The K+-channel KcsA is the most popular model protein among these complexes. The presence of zwitterionic nonbilayer lipid phosphatidylethanolamine (PE) is crucial for efficient tetramerization and stabilization of KcsA in a lipid bilayer. In this study, the influence of PE on KcsA folding properties was analyzed by tryptophan fluorescence and acrylamide quenching experiments and compared with the effect of anionic phosphatidic acid (PA). The preliminary studies suggest that the small size and hydrogen bonding capability of the PE headgroup influences KcsA folding via a mechanism quite similar to that observed for anionic PA.
George W Gokel - One of the best experts on this subject based on the ideXlab platform.
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activity of synthetic ion channels is influenced by cation π interactions with phospholipid Headgroups
Organic and Biomolecular Chemistry, 2006Co-Authors: Michelle E Weber, Elizabeth K Elliott, George W GokelAbstract:A suite of synthetic hydraphile ion channels has been used to probe the possibility of cation–π interactions between the channel and the phospholipid bilayer. The hydraphiles selected for this study contained either no sidearm, aliphatic sidearms or aromatic sidearms that varied in electron-richness. An ion selective electrode (ISE) method was used to evaluate the ion transport ability of these hydraphiles across synthetic bilayers. Transport was dependent on sidearm identity. Ion transport activity for the aromatic sidechained compounds was greatest when the sidearms were electron rich and vesicles were prepared from 100% DOPC (trimethylammonium cation headgroup, overall neutral). When the lipid Headgroups were made more negative by changing the composition from DOPC to 70 : 30 (w/w) DOPC : DOPA, transport by the aromatic-sidechained channels was reduced. Fluorescence studies showed that when the lipid composition changed, the Headgroups experienced a different polarity, suggesting reorientation. The data are in accord with a stabilizing cation–π interaction between the aromatic sidearm of the hydraphile channel and the ammonium phospholipid headgroup.
