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Biochemistry and Biophysics of Archaea Membranes

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Biophysics".

Deadline for manuscript submissions: closed (30 April 2020) | Viewed by 20281

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Special Issue Editors

Prof. Dr. Parkson Lee-Gau Chong

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Guest Editor

Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine at Temple University, 3420 North Broad Street, Philadelphia, PA 19140, USA
Interests: liposomes; fluorescence; drug delivery; membrane biophysics
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Hans-Joachim Freisleben

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Co-Guest Editor

Faculty of Medicine Universitas Indonesia (FMUI), Depok, Indonesia
Interests: Archaea; thermoplasmatales; archaeal tetraether lipid; liposomal therapeutic systems; archaeosomes; mitochondrial energy turnover; hypoxia, ischemia and reperfusion injury; reactive oxygen species and antioxidants; iron overload and oxidative stress in ß-thalassemia; iron- chelating and antioxidant plant extracts

Special Issue Information

Dear colleagues,

Archaea are a domain of life that is distinctly different from bacteria and eukarya, with the most noticeable difference lying in their cell membrane. To date, archaeal lipid membranes and membrane proteins have been extensively studied. However, many critical biochemical and biophysical issues related to archaea membranes remain elusive. Archaea inhabit extreme environments such as volcanic areas; deep sea hydrothermal vents; as well as non-extreme environments such as soils, lakes, and pelagic areas. How the cytoplasmic membrane of archaea adapts to such a wide variety of environments is still an active research area. All archaea contain an S-layer as the outermost shell. Protein insertion into and transport across the cytoplasmic membrane, as well as protein interaction with the S-layer, are currently topics of many interesting studies. Why the dominating lipids in the cytoplasmic membrane of crenarchaeota do not appear in the microvesicles released from the cell is a mystery and a topic currently under active investigation. Tetraether lipids, which are the dominating lipid species, particularly in crenarchaeota, are extremely stable. In recent years, there is an increase in archaeosome usage for gene and drug delivery. As such, it is timely to compile a Special Issue to report or review the new findings on archaea membrane.

The topics to be covered in this Special Issue entitled “Biochemistry and Biophysics of Archaea Membranes” include but are not limited to the following:

- The structural characterization of newly found native or newly synthesized archaeal lipids;
- Lipidomics or proteomics of archaea membranes;
- The structure (including protein folding and trafficking) and function of archaea membrane proteins;
- The dynamics and organization of archaea membranes;
- Archaea membrane adaptation to environmental stress;
- Studies on microvesicles released from archaea;
- Computer simulations of archaea membranes;
- The use of archaeosomes and archaea lipid planar membranes for technology applications.

Prof. Dr. Parkson Lee-Gau Chong
Prof. Dr. Hans-Joachim Freisleben
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

archaea proteins
tetraether lipids
cytoplasmic membrane
lipid–protein interactions
membrane adaptation
archaeosomes
physicochemical characterization

Published Papers (6 papers)

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Research

Jump to: Review

11 pages, 1606 KiB

Open AccessArticle

Non-Polar Lipids as Regulators of Membrane Properties in Archaeal Lipid Bilayer Mimics

by Marta Salvador-Castell, Nicholas J. Brooks, Roland Winter, Judith Peters and Philippe M. Oger

Int. J. Mol. Sci. 2021, 22(11), 6087; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22116087 - 04 Jun 2021

Cited by 2 | Viewed by 2617

Abstract

The modification of archaeal lipid bilayer properties by the insertion of apolar molecules in the lipid bilayer midplane has been proposed to support cell membrane adaptation to extreme environmental conditions of temperature and hydrostatic pressure. In this work, we characterize the insertion effects of the apolar polyisoprenoid squalane on the permeability and fluidity of archaeal model membrane bilayers, composed of lipid analogues. We have monitored large molecule and proton permeability and Laurdan generalized polarization from lipid vesicles as a function of temperature and hydrostatic pressure. Even at low concentration, squalane (1 mol%) is able to enhance solute permeation by increasing membrane fluidity, but at the same time, to decrease proton permeability of the lipid bilayer. The squalane physicochemical impact on membrane properties are congruent with a possible role of apolar intercalants on the adaptation of Archaea to extreme conditions. In addition, such intercalant might be used to cheaply create or modify chemically resistant liposomes (archeaosomes) for drug delivery. Full article

(This article belongs to the Special Issue Biochemistry and Biophysics of Archaea Membranes)

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12 pages, 3343 KiB

Open AccessArticle

Structural Characterization of an Archaeal Lipid Bilayer as a Function of Hydration and Temperature

by Marta Salvador-Castell, Bruno Demé, Philippe Oger and Judith Peters

Int. J. Mol. Sci. 2020, 21(5), 1816; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms21051816 - 06 Mar 2020

Cited by 6 | Viewed by 2386

Abstract

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 70 °C 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. Full article

(This article belongs to the Special Issue Biochemistry and Biophysics of Archaea Membranes)

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17 pages, 1619 KiB

Open AccessArticle

Sulfolobus acidocaldarius Microvesicles Exhibit Unusually Tight Packing Properties as Revealed by Optical Spectroscopy

by Alexander Bonanno, Robert C. Blake II and Parkson Lee-Gau Chong

Int. J. Mol. Sci. 2019, 20(21), 5308; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms20215308 - 25 Oct 2019

Cited by 4 | Viewed by 2358

Abstract

In this study, we used optical spectroscopy to characterize the physical properties of microvesicles released from the thermoacidophilic archaeon Sulfolobus acidocaldarius (Sa-MVs). The most abundant proteins in Sa-MVs are the S-layer proteins, which self-assemble on the vesicle surface forming an array of crystalline structures. Lipids in Sa-MVs are exclusively bipolar tetraethers. We found that when excited at 275 nm, intrinsic protein fluorescence of Sa-MVs at 23 °C has an emission maximum at 303 nm (or 296 nm measured at 75 °C), which is unusually low for protein samples containing multiple tryptophans and tyrosines. In the presence of 10–11 mM of the surfactant n-tetradecyl-β-d-maltoside (TDM), Sa-MVs were disintegrated, the emission maximum of intrinsic protein fluorescence was shifted to 312 nm, and the excitation maximum was changed from 288 nm to 280.5 nm, in conjunction with a significant decrease (>2 times) in excitation band sharpness. These data suggest that most of the fluorescent amino acid residues in native Sa-MVs are in a tightly packed protein matrix and that the S-layer proteins may form J-aggregates. The membranes in Sa-MVs, as well as those of unilamellar vesicles (LUVs) made of the polar lipid fraction E (PLFE) tetraether lipids isolated from S. acidocaldarius (LUV_PLFE), LUVs reconstituted from the tetraether lipids extracted from Sa-MVs (LUV_MV) and LUVs made of the diester lipids, were investigated using the probe 6-dodecanoyl-2-dimethylaminonaphthalene (Laurdan). The generalized polarization (GP) values of Laurdan in tightly packed Sa-MVs, LUV_MV, and LUV_PLFE were found to be much lower than those obtained from less tightly packed DPPC gel state, which echoes the previous finding that the GP values from tetraether lipid membranes cannot be directly compared with the GP values from diester lipid membranes, due to differences in probe disposition. Laurdan’s GP and red-edge excitation shift (REES) values in Sa-MVs and LUV_MV decrease with increasing temperature monotonically with no sign for lipid phase transition. Laurdan’s REES values are high (9.3–18.9 nm) in the tetraether lipid membrane systems (i.e., Sa-MVs, LUV_MV and LUV_PLFE) and low (0.4–5.0 nm) in diester liposomes. The high REES and low GP values suggest that Laurdan in tetraether lipid membranes, especially in the membrane of Sa-MVs, is in a very motionally restricted environment, bound water molecules and the polar moieties in the tetraether lipid headgroups strongly interact with Laurdan’s excited state dipole moment, and “solvent” reorientation around Laurdan’s chromophore in tetraether lipid membranes occurs very slowly compared to Laurdan’s lifetime. Full article

(This article belongs to the Special Issue Biochemistry and Biophysics of Archaea Membranes)

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Review

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22 pages, 2086 KiB

Open AccessReview

The Cell Membrane of Sulfolobus spp.—Homeoviscous Adaption and Biotechnological Applications

by Kerstin Rastädter, David J. Wurm, Oliver Spadiut and Julian Quehenberger

Int. J. Mol. Sci. 2020, 21(11), 3935; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms21113935 - 30 May 2020

Cited by 15 | Viewed by 3939

Abstract

The microbial cell membrane is affected by physicochemical parameters, such as temperature and pH, but also by the specific growth rate of the host organism. Homeoviscous adaption describes the process of maintaining membrane fluidity and permeability throughout these environmental changes. Archaea, and thereby, Sulfolobus spp. exhibit a unique lipid composition of ether lipids, which are altered in regard to the ratio of diether to tetraether lipids, number of cyclopentane rings and type of head groups, as a coping mechanism against environmental changes. The main biotechnological application of the membrane lipids of Sulfolobus spp. are so called archaeosomes. Archaeosomes are liposomes which are fully or partly generated from archaeal lipids and harbor the potential to be used as drug delivery systems for vaccines, proteins, peptides and nucleic acids. This review summarizes the influence of environmental parameters on the cell membrane of Sulfolobus spp. and the biotechnological applications of their membrane lipids. Full article

(This article belongs to the Special Issue Biochemistry and Biophysics of Archaea Membranes)

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26 pages, 12940 KiB

Open AccessReview

The Main (Glyco) Phospholipid (MPL) of Thermoplasma acidophilum

by Hans-Joachim Freisleben

Int. J. Mol. Sci. 2019, 20(20), 5217; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms20205217 - 21 Oct 2019

Cited by 6 | Viewed by 3828

Abstract

The main phospholipid (MPL) of Thermoplasma acidophilum DSM 1728 was isolated, purified and physico-chemically characterized by differential scanning calorimetry (DSC)/differential thermal analysis (DTA) for its thermotropic behavior, alone and in mixtures with other lipids, cholesterol, hydrophobic peptides and pore-forming ionophores. Model membranes from MPL were investigated; black lipid membrane, Langmuir-Blodgett monolayer, and liposomes. Laboratory results were compared to computer simulation. MPL forms stable and resistant liposomes with highly proton-impermeable membrane and mixes at certain degree with common bilayer-forming lipids. Monomeric bacteriorhodopsin and ATP synthase from Micrococcus luteus were co-reconstituted and light-driven ATP synthesis measured. This review reports about almost four decades of research on Thermoplasma membrane and its MPL as well as transfer of this research to Thermoplasma species recently isolated from Indonesian volcanoes. Full article

(This article belongs to the Special Issue Biochemistry and Biophysics of Archaea Membranes)

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26 pages, 4523 KiB

Open AccessReview

In Search for the Membrane Regulators of Archaea

by Marta Salvador-Castell, Maxime Tourte and Philippe M. Oger

Int. J. Mol. Sci. 2019, 20(18), 4434; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms20184434 - 09 Sep 2019

Cited by 25 | Viewed by 4518

Abstract

Membrane regulators such as sterols and hopanoids play a major role in the physiological and physicochemical adaptation of the different plasmic membranes in Eukarya and Bacteria. They are key to the functionalization and the spatialization of the membrane, and therefore indispensable for the cell cycle. No archaeon has been found to be able to synthesize sterols or hopanoids to date. They also lack homologs of the genes responsible for the synthesis of these membrane regulators. Due to their divergent membrane lipid composition, the question whether archaea require membrane regulators, and if so, what is their nature, remains open. In this review, we review evidence for the existence of membrane regulators in Archaea, and propose tentative location and biological functions. It is likely that no membrane regulator is shared by all archaea, but that they may use different polyterpenes, such as carotenoids, polyprenols, quinones and apolar polyisoprenoids, in response to specific stressors or physiological needs. Full article

(This article belongs to the Special Issue Biochemistry and Biophysics of Archaea Membranes)

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