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1. Membrane adaptation in the hyperthermophilic archaeon Pyrococcus furiosus relies upon a novel strategy involving glycerol monoalkyl glycerol tetraether lipids

Author

Maxime Tourte, Vincent Grossi, Philippe Schaeffer, Philippe Oger, Microbiologie, adaptation et pathogénie (MAP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de Strasbourg, Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE11-0012,ArchaeoMembranes,Des bicouches lipidiques stables au delà du point d'ébullition de l'eau(2017), Microbiology of Extreme Environments (M2E), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon)

Subjects
Glycerol, Pyrococcus, H-shaped lipids, [SDV]Life Sciences [q-bio], chemistry.chemical_element, Microbiology, 03 medical and health sciences, chemistry.chemical_compound, Membrane Lipids, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, tetraethers, Carbon source, Ecology, Evolution, Behavior and Systematics, extremophiles, 030304 developmental biology, 0303 health sciences, Archaeal membrane lipids, biology, 030306 microbiology, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, stress response, biology.organism_classification, Sulfur, Archaea, Carbon, Salinity, Pyrococcus furiosus, Membrane, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, chemistry, Biochemistry, Adaptation
Abstract

Microbes preserve membrane functionality under fluctuating environmental conditions by modulating their membrane lipid composition. Although several studies have documented membrane adaptations in Archaea, the influence of most biotic and abiotic factors on archaeal lipid compositions remains underexplored. Here, we studied the influence of temperature, pH, salinity, the presence/absence of elemental sulfur, the carbon source, and the genetic background on the core lipid composition of the hyperthermophilic neutrophilic marine archaeon Pyrococcus furiosus. Every growth parameter tested affected the core lipid composition to some extent, the carbon source and the genetic background having the greatest influence. Surprisingly, P. furiosus appeared to only marginally rely on the two major responses implemented by Archaea, i.e., the regulation of the ratio of diether to tetraether lipids and that of the number of cyclopentane rings in tetraethers. Instead, this species increased the ratio of glycerol monoalkyl glycerol tetraethers (GMGT, aka. H-shaped tetraethers) to glycerol dialkyl glycerol tetrathers (GDGT) in response to decreasing temperature and pH and increasing salinity, thus providing for the first time evidence of adaptive functions for GMGT. Besides P. furiosus, numerous other species synthesize significant proportions of GMGT, which suggests that this unprecedented adaptive strategy might be common in Archaea.Significance statementWe describe here the membrane adaptive strategies the hyperthermophilic, neutrophilic, and marine model archaeon Pyrococcus furiosus implements in response to one of the largest sets of environmental stressors tested to date, including temperature, pH, salinity, presence/absence of elemental sulfur, carbon source, and genetic background. In contrast to the other archaea investigated so far, which response mainly involves the modulation of their diether/tetraether ratio and/or of their average number of cyclopentane rings, P. furiosus regulates its monoalkyl (so called H-shaped) to dialkyl tetraether ratio. Our study thus provides for the first time evidence of adaptive functions of archaeal monoalkyl tetraethers towards low temperature and pH and high salinity.

Published
2022
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2. Acyclic Polyisoprenoid Hydrocarbons: Fundamental Regulators of the Archaeal Membrane?

Author

Vincent Grossi, Maxime Tourte, Philippe Schaeffer, Phil M. Oger, Microbiologie, adaptation et pathogénie (MAP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Institut de Chimie de Strasbourg, Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Chain length, Membrane, Phylogenetic tree, biology, Biochemistry, Chemistry, Lipid composition, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, biology.organism_classification, Hopanoids, Bacteria, ComputingMilieux_MISCELLANEOUS, Archaea
Abstract

Summary Sterols and hopanoids, the typical membrane regulators of Eukaryotes and Bacteria, are absent from Archaea, which might instead use acyclic polyisoprenoid hydrocarbons (APH). Although a few studies evidenced that APH do modulate membrane physicochemical properties as other membrane regulators, little is known about these intriguing compounds in the third domain of life. In an effort to elucidate APH distribution, physiological and adaptive functions, and biosynthetic pathway in Archaea, we collected all the literature data available and evaluated the APH composition of 65 archaeal species homogeneously distributed within the phylogenetic tree and ecological niches of Archaea. Fully saturated to fully unsaturated 30, 35, and 40-carbon long APH were detected in most species investigated, regardless of their phylogenetic position, lipid composition, or preferential environmental conditions, although the chain length could be correlated with growth conditions. Despite such a wide occurrence of APH in Archaea, only rare homologues of the eukaryotic and bacterial APH biosynthetic pathways were found. How they synthesize these compounds thus remains elusive and lipid analysis still prevails as the only mean to assess the production and functions of these essential archaeal membrane components.

Published
2021
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3. Uncommon Glycerol Monoalkyl Glycerol Tetraethers (GMGT) Support Membrane Adaption in the Archaeon Pyrococcus Furiosus

Author

Phil M. Oger, Maxime Tourte, Vincent Grossi, Philippe Schaeffer, Microbiologie, adaptation et pathogénie (MAP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de Strasbourg, Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Abiotic component, biology, Chemistry, chemistry.chemical_element, Homeoviscous adaptation, biology.organism_classification, Sulfur, Salinity, chemistry.chemical_compound, Membrane, Biochemistry, 13. Climate action, Pyrococcus furiosus, Glycerol, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, ComputingMilieux_MISCELLANEOUS, Archaea
Abstract

Summary Microbes preserve membrane functionality under fluctuating environmental conditions by modulating their membrane lipid composition, a strategy termed homeoviscous adaptation. Although several studies have documented this strategy in Archaea, the influence of the majority of biotic and abiotic factors on archaeal lipid compositions remains unexplored. To constrain the homeoviscous adaptation strategies in Archaea, we studied the influence of temperature, pH, salinity, elemental sulfur, carbon source, and genetic background on the remarkable core lipid composition of the hyperthermophilic and neutrophilic marine archaeon Pyrococcus furiosus. Most growth parameters tested here affected its core lipid composition, the carbon source and the genetic background having the greatest influences. Surprisingly, P. furiosus membrane adaptation appears to marginally rely on the two major homeoviscous responses implemented by Archaea, i.e., the regulation of the ratio between diethers and tetraethers and of the number of cyclopentane-rings in tetraethers. Instead, it increases the ratio of monoalkyl (GMGT) over dialkyl (GDGT) tetrathers in response to decreasing temperature and pH and increasing salinity. Besides P. furiosus, numerous other species synthesize significant proportions of GMGT, which indicates that this unprecedented homeoviscous strategy might be common in Archaea. This paves the way for developing novel, GMGT-based environmental proxies.

Published
2021
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4. Reappraisal of archaeal C20-C25 diether lipid (extended archaeol) origin and use as a biomarker of hypersalinity

Author

Maxime Tourte, Philippe Schaeffer, Flore Vandier, Vincent Grossi, Julien Plancq, Cara Doumbe-Kingue, Phil M. Oger, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Microbiologie, adaptation et pathogénie (MAP), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon, Microbiology of Extreme Environments (M2E), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Strasbourg (UNISTRA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), School of Geographical and Earth Sciences [Univ Glasgow], University of Glasgow, Institut de Chimie de Strasbourg, Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDE.MCG]Environmental Sciences/Global Changes, Zoology, 010502 geochemistry & geophysics, [SDV.BID.SPT]Life Sciences [q-bio]/Biodiversity/Systematics, Phylogenetics and taxonomy, 01 natural sciences, Natrialbales, 03 medical and health sciences, chemistry.chemical_compound, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, adaptation to pH and salinity, Statistical analysis, Archaeol, 0105 earth and related environmental sciences, 0303 health sciences, biology, 030306 microbiology, Saturation (genetic), biology.organism_classification, extended archaeol, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, Halophilic archaea, Salinity, Biomarker (petroleum), chemistry, Haloarchaea, lipids (amino acids, peptides, and proteins), Archaea
Abstract

International audience; The diether core membrane lipid sesterterpanyl-phytanyl-glycerol (so-called extended archaeol and often abbreviated C 20-C 25) is considered as a hallmark of Haloarchaea, a clade of archaea thriving under extreme high salinities. We here report about extended archaeol occurrence in different saline aquatic settings with salinity ranging from ca. 50 psu (5 % NaCl w/v) to saturation (ca. 350 psu). This demonstrates that this lipid is not restricted to extreme saline environments but suggests a minimum salinity threshold of ca. 50 psu above which C 20-C 25 is most commonly produced. The proportion of C 20-C 25 relative to that of archaeol (C 20-C 20) did not appear linearly dependent on the salinity of the site and was potentially also influenced by pH and temperature, preventing its direct use as a quantitative salinity proxy based on the present data set. An extensive literature review of archaeal membrane lipid compositions further highlighted that taxonomy also contributes to the distribution of this lipid in the environment and identifies Natrialbales (one of the three orders of Haloarchaea) as the main source. Statistical analysis showed that, among Haloarchaea, C 20-C 25 producers display pH and salinity growth optima slightly higher than non-producers and are distributed within two distinct groups, one composed mostly of neutrophiles and one of alkaliphiles. In contrast, the presence of C 20-C 25 was not correlated to the optimal growth temperature of the strains. This suggests that two confounding parameters, i.e., taxonomy and adaptation to changes in salinity and/or pH, contribute to the distribution of C 20-C 25 within Haloarchaea.

Published
2021
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5. Functionalized Membrane Domains: An Ancestral Feature of Archaea?

Author

Philippe Schaeffer, Phil M. Oger, Maxime Tourte, Vincent Grossi, Microbiologie, adaptation et pathogénie (MAP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Microbiology of Extreme Environments (M2E), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Institut de Chimie de Strasbourg, Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Microorganismes : Génome et Environnement - Clermont Auvergne (LMGE), Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE11-0012,ArchaeoMembranes,Des bicouches lipidiques stables au delà du point d'ébullition de l'eau(2017), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Microbiology (medical), lcsh:QR1-502, [SDV.BC.BC]Life Sciences [q-bio]/Cellular Biology/Subcellular Processes [q-bio.SC], adaptation, Microbiology, lcsh:Microbiology, 03 medical and health sciences, Pyrococcus horikoshii, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, evolution, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, Original Research, 0303 health sciences, biology, 030306 microbiology, Chemistry, Bilayer, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, biology.organism_classification, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, Archaea, Thermococcales, [SDV.BBM.BP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics, Thermococcus barophilus, Membrane, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, Membrane protein, membrane domains, membrane architecture, Biophysics, membrane function, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, archaeal lipids, Bacteria
Abstract

International audience; Bacteria and Eukarya organize their plasma membrane spatially into domains of distinct functions. Due to the uniqueness of their lipids, membrane functionalization in Archaea remains a debated area. A novel membrane ultrastructure predicts that monolayer and bilayer domains would be laterally segregated in the hyperthermophilic archaeon Thermococcus barophilus. With very different physico-chemical parameters of the mono-and bilayer, each domain type would thus allow the docking of different membrane proteins and express different biological functions in the membrane. To estimate the ubiquity of this putative membrane ultrastructure in and out of the order Thermococcales, we re-analyzed the core lipid composition of all the Thermococcales type species and collected all the literature data available for isolated archaea. We show that all species of Thermococcales synthesize a mixture of diether bilayer forming and tetraether monolayer forming lipids, in various ratio from 10 to 80% diether in Pyrococcus horikoshii and Thermococcus gorgonarius, respectively. Since the domain formation prediction rests only on the coexistence of di-and tetraether lipids, we show that all Thermococcales have the ability for domain formation, i.e., differential functionalization of their membrane. Extrapolating this view to the whole Archaea domain, we show that almost all archaea also have the ability to synthesize di-and tetraether lipids, which supports the view that functionalized membrane domains may be shared between all Archaea. Hence domain formation and membrane compartmentalization may have predated the separation of the three domains of life and be essential for the cell cycle.

Published
2020
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6. In Search for the Membrane Regulators of Archaea

Author

Marta Salvador-Castell, Philippe Oger, Maxime Tourte, Microbiologie, adaptation et pathogénie (MAP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Microbiology of Extreme Environments (M2E), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon, and Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon)

Subjects
0301 basic medicine, Polyterpenes, archaea, Lipid composition, 030106 microbiology, Regulator, Review, adaptation, Catalysis, lcsh:Chemistry, Inorganic Chemistry, 03 medical and health sciences, Membrane Lipids, neutron diffraction, polyterpenes, polyisoprenoids, polyprenols, diphytanyl phospholipids, Physical and Theoretical Chemistry, ether lipids, lcsh:QH301-705.5, Molecular Biology, Gene, Spectroscopy, quinones, biology, Chemistry, Organic Chemistry, Cell Membrane, carotenoids, General Medicine, membrane organization, biology.organism_classification, Adaptation, Physiological, Hopanoids, Computer Science Applications, [SDV.BBM.BP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics, 030104 developmental biology, Membrane, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, lcsh:Biology (General), lcsh:QD1-999, Biochemistry, phase transition, lipids (amino acids, peptides, and proteins), membrane modulators, Bacteria, Archaea
Abstract

International audience; Archaea, the most extremophilic domain of life, contain ether and branched lipids which provide extraordinary bilayer properties. We determined the structural characteristics of diether archaeal-like phospholipids as functions of hydration and temperature by neutron diffraction. Hydration and temperature are both crucial parameters for the self-assembly and physicochemical properties of lipid bilayers. In this study, we detected non-lamellar phases of archaeal-like lipids at low hydration levels, and lamellar phases at levels of 90% relative humidity or more exclusively. Moreover, at 90% relative humidity, a phase transition between two lamellar phases was discernible. At full hydration, lamellar phases were present up to 70ᵒC and no phase transition was observed within the temperature range studied (from 25 °C to 70 °C). In addition, we determined the neutron scattering length density and the bilayer's structural parameters from different hydration and temperature conditions. At the highest levels of hydration, the system exhibited rearrangements on its corresponding hydrophobic region. Furthermore, the water uptake of the lipids examined was remarkably high. We discuss the effect of ether linkages and branched lipids on the exceptional characteristics of archaeal phospholipids.

Published
2019
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