1
|
Simeral ML, Demers SME, Sheth K, Hafner JH. A Raman spectral marker for the iso-octyl chain structure of cholesterol. ANALYTICAL SCIENCE ADVANCES 2024; 5:2300057. [PMID: 38828085 PMCID: PMC11142391 DOI: 10.1002/ansa.202300057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 11/17/2023] [Indexed: 06/05/2024]
Abstract
Raman spectroscopy provides label-free, specific analysis of biomolecular structure and interactions. It could have a greater impact with improved characterization of complex fingerprint vibrations. Many Raman peaks have been assigned to cholesterol, for example, but the molecular vibrations associated with those peaks are not known. In this report, time-dependent density functional theory calculations of the Raman spectrum of cholesterol are compared to measurements on microcrystalline powder to identify 23 peaks in the Raman spectrum. Among them, a band of six peaks is found to be sensitive to the conformational structure of cholesterol's iso-octyl chain. Calculations on 10 conformers in this spectral band are fit to experimental spectra to probe the cholesterol chain structure in purified powder and in phospholipid vesicles. In vesicles, the chain is found to bend perpendicular to the steroid rings, supporting the case that the chain is a dynamic structure that contributes to lipid condensation and other effects of cholesterol in biomembranes. Statement of Significance: Here we use density functional theory to identify a band of six peaks in cholesterol's Raman spectrum that is sensitive to the conformational structure of cholesterol's chain. Raman spectra were analyzed to show that in fluid-phase lipid membranes, about half of the cholesterol chains point perpendicular to the steroid rings. This new method of label-free structural analysis could make significant contributions to our understanding of cholesterol's critical role in biomembrane structure and function. More broadly, the results show that computational quantum chemistry Raman spectroscopy can make significant new contributions to molecular structure when spectra are interpreted with computational quantum chemistry.
Collapse
Affiliation(s)
| | | | - Kyle Sheth
- Department of Physics and AstronomyRice UniversityHoustonTexasUSA
| | - Jason H. Hafner
- Department of Physics and AstronomyRice UniversityHoustonTexasUSA
- Department of ChemistryRice UniversityHoustonTexasUSA
| |
Collapse
|
2
|
Ondevilla JC, Hanashima S, Mukogawa A, Miyazato DG, Umegawa Y, Murata M. Effect of the number of sugar units on the interaction between diosgenyl saponin and membrane lipids. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184145. [PMID: 36914020 DOI: 10.1016/j.bbamem.2023.184145] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 03/01/2023] [Accepted: 03/01/2023] [Indexed: 03/15/2023]
Abstract
Saponin is the main bioactive component of the Dioscorea species, which are traditionally used for treating chronic diseases. An understanding of the interaction process of bioactive saponins with biomembranes provides insights into their development as therapeutic agents. The biological effects of saponins have been thought to be associated with membrane cholesterol (Chol). To shed light on the exact mechanisms of their interactions, we investigated the effects of diosgenyl saponins trillin (TRL) and dioscin (DSN) on the dynamic behavior of lipids and membrane properties in palmitoyloleolylphosphatidylcholine (POPC) bilayers using solid-state NMR and fluorescence spectroscopy. The membrane effects of diosgenin, a sapogenin of TRL and DSN, are similar to those of Chol, suggesting that diosgenin plays a major role in membrane binding and POPC chain ordering. The amphiphilicity of TRL and DSN enabled them to interact with POPC bilayers, regardless of Chol. In the presence of Chol, the sugar residues more prominently influenced the membrane-disrupting effects of saponins. The activity of DSN, which bears three sugar units, led to perturbation and further disruption of the membrane in the presence of Chol. However, TRL, which bears one sugar residue, increased the ordering of POPC chains while maintaining the integrity of the bilayer. This effect on the phospholipid bilayers is similar to that of cholesteryl glucoside. The influence of the number of sugars in saponin is discussed in more detail.
Collapse
Affiliation(s)
- Joan Candice Ondevilla
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Department of Chemistry, De La Salle University, 2401 Taft Avenue, Manila 0922, Philippines
| | - Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-cho Minami, Tottori 680-8552, Japan.
| | - Akane Mukogawa
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Darcy Garza Miyazato
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Yuichi Umegawa
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Forefront Research Centre for Fundamental Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Forefront Research Centre for Fundamental Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
| |
Collapse
|
3
|
Paulose SK, Chakraborty K. Anti-hyperglycemic Δ 5 steroids, marginoids A-C from marine veined octopus Amphioctopus marginatus (Octopodidae): Prospective natural leads inhibit serineexopeptidase dipeptidyl peptidase-4. Steroids 2022; 186:109090. [PMID: 35850257 DOI: 10.1016/j.steroids.2022.109090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/25/2022] [Accepted: 07/01/2022] [Indexed: 10/17/2022]
Abstract
Three Δ5 steroid analogues, marginoids A-C were purified from the organic extract of marine veined octopus Amphioctopus marginatus (Taki, 1964) (family Octopodidae) distributed on the Asian and Mediterranean coasts. Their structures were elucidated as (5Z)-3β-acetoxy-cholesta-5-en-25-ethylene-22β-hydroxy-23,26-lactone (marginoid A), (5Z, 25Z)-3β-yl-(1'-(E)-3'-hydroxy-4'-methyl-hex-5'-enoate)-22-oxo-26-furanyl-cholesta-5,25-diene (marginoid B), and (5Z)-3β-yl-(7'-methoxypropan-8'-yl)-tetrahydro-2H-pyran-2-one-cholesta-5,24-dien (marginoid C) based on extensive spectroscopic experiments. Marginoid B with hydroxyl-methyl-hexanoate at the C-3 position in conjunction with the heterocyclic furanyl ring displayed superior anti-hyperglycemic properties as acknowledged by its promising serine protease dipeptidyl peptidase-4 attenuation potential (IC50 3.49 µM) displaying comparable activity with the standard DPP-4 inhibitor (DPP-4i) diprotin A (IC50 4.53 µM). The anti-hyperglycemic properties were corroborated by the promising antioxidant activities (IC50 ∼ 0.8-1.0 mM) of these Δ5 steroids, marginoids A-C. Sizeably greater electronic properties, balanced hydrophobic-lipophilic properties (log POW 6.4-8.3), and comparatively lower steric factors were directly proportional to their bioactive properties. Molecular simulation studies in the binding sites of DPP-4 and lesser binding energy (-12.17 kcal/mol) and inhibition constant (Ki 1.20 nM) of marginoid B could be correlated with anti-hyperglycemic properties. Promising bioactivities of marginoid B isolated from A. marginatus are anticipated for nutraceutical applications against hyperglycemia.
Collapse
Affiliation(s)
- Silpa Kunnappilly Paulose
- Marine Bioprospecting Section of Marine Biotechnology, Fish Nutrition and Health Division, Central Marine Fisheries Research Institute, Ernakulam North, P.B. No. 1603, Cochin, India
| | - Kajal Chakraborty
- Marine Bioprospecting Section of Marine Biotechnology, Fish Nutrition and Health Division, Central Marine Fisheries Research Institute, Ernakulam North, P.B. No. 1603, Cochin, India.
| |
Collapse
|
4
|
Sterols are required for the coordinated assembly of lipid droplets in developing seeds. Nat Commun 2021; 12:5598. [PMID: 34552075 PMCID: PMC8458542 DOI: 10.1038/s41467-021-25908-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 09/09/2021] [Indexed: 12/23/2022] Open
Abstract
Lipid droplets (LDs) are intracellular organelles critical for energy storage and lipid metabolism. They are typically composed of an oil core coated by a monolayer of phospholipids and proteins such as oleosins. The mechanistic details of LD biogenesis remain poorly defined. However, emerging evidence suggest that their formation is a spatiotemporally regulated process, occurring at specific sites of the endoplasmic reticulum defined by a specific set of lipids and proteins. Here, we show that sterols are required for formation of oleosin-coated LDs in Arabidopsis. Analysis of sterol pathway mutants revealed that deficiency in several ∆5-sterols accounts for the phenotype. Importantly, mutants deficient in these sterols also display reduced LD number, increased LD size and reduced oil content in seeds. Collectively, our data reveal a role of sterols in coordinating the synthesis of oil and oleosins and their assembly into LDs, highlighting the importance of membrane lipids in regulating LD biogenesis. Lipid droplet biogenesis originates at the endoplasmic reticulum and is defined by a specific set of lipids and proteins. Here, the authors show that sterols play an important role in coordinating oil and oleosin biosynthesis for the formation of lipid droplets in plant leaves and seeds.
Collapse
|
5
|
Ondevilla JC, Hanashima S, Mukogawa A, Umegawa Y, Murata M. Diosgenin-induced physicochemical effects on phospholipid bilayers in comparison with cholesterol. Bioorg Med Chem Lett 2021; 36:127816. [PMID: 33516912 DOI: 10.1016/j.bmcl.2021.127816] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/12/2021] [Accepted: 01/17/2021] [Indexed: 10/22/2022]
Abstract
Diosgenin (DGN), which is a sterol occurring in plants of the Dioscorea family, has attracted increasing attention for its various pharmacological activities. DGN has a structural similarity to cholesterol (Cho). In this study we investigated the effects of the common tetracyclic cores and the different side chains on the physicochemical properties of lipid bilayer membranes. Differential scanning calorimetry showed that DGN and Cho reduce the phase transition enthalpy to a similar extent. In 2H NMR, deuterated-DGN/Cho and POPC showed similar ordering in POPC bilayers, which revealed that DGN is oriented parallel to the membrane normal like Cho. It was suggested that the affinity of DGN-Cho in membrane is stronger than that of DGN-DGN or Cho-Cho interaction. 31P NMR of POPC in bilayers revealed that, unlike Cho, DGN altered the interactions of POPC headgroups at 30 mol%. These results suggest that DGN below 30 mol% has similar effects with Cho on basic biomembrane properties.
Collapse
Affiliation(s)
- Joan Candice Ondevilla
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
| | - Akane Mukogawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan; ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yuichi Umegawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan; ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
| |
Collapse
|
6
|
Salas S, Chakraborty K. First report of bioactive sterols from the muricid gastropod Chicoreus ramosus. Steroids 2018; 137:57-63. [PMID: 30055192 DOI: 10.1016/j.steroids.2018.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 06/21/2018] [Accepted: 07/09/2018] [Indexed: 01/07/2023]
Abstract
Two unusual △5 sterols with unprecedented skeletons were isolated from the organic extract of muricid gastropod Chicoreus ramosus collected off the Gulf of Mannar Coast. This is the first report of isolation of bioactive sterols endowed with anti-inflammatory potentials from this species. The compounds were characterized as (5Z)-24a-homo-cholesta-5,24a1(24a2) dien-3β-ol (1) and 27(25 → 23)-abeo-(5Z)-3β-hydroxy-24-isopropyl cholesteno-26,23-lactone (2) by the interpretation of a series of spectroscopic techniques involving two-dimensional nuclear magnetic resonance and mass spectral data. The compound 1 is unusual in that it has an ethylene attachment stemming from the additional methylene group at the 24a position of the steroid side chain, whereas compound 2 has a unique side chain bearing a γ-valerolactone ring. The △5 sterol bearing ethylene group (1) displayed comparatively better antidiabetic activity as characterized by inhibitory effects towards α-amylase and α-glucosidase enzymes (IC50 1.97 mM and 1.78 mM, respectively), whereas the cholestenolactone analogue (2) manifested higher anti-inflammatory activity (IC50 1.42 mM) as determined by in vitro 5-lipoxygenase inhibitory potential. Structure-activity correlation study showed that the biological activities of the studied sterols were directly related to their electronic properties. The homosterol (1) exhibiting improved antidiabetic properties showed higher lipophilic character coupled with lesser steric restrictions.
Collapse
Affiliation(s)
- Soumya Salas
- Department of Chemistry, Mangalore University, Mangalagangothri-574199, Karnataka State, India
| | - Kajal Chakraborty
- Department of Chemistry, Mangalore University, Mangalagangothri-574199, Karnataka State, India.
| |
Collapse
|
7
|
Importance of Hydrophilic Groups on Modulating the Structural, Mechanical, and Interfacial Properties of Bilayers: A Comparative Molecular Dynamics Study of Phosphatidylcholine and Ion Pair Amphiphile Membranes. Int J Mol Sci 2018; 19:ijms19061552. [PMID: 29882873 PMCID: PMC6032153 DOI: 10.3390/ijms19061552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/16/2018] [Accepted: 05/18/2018] [Indexed: 12/25/2022] Open
Abstract
An ion pair amphiphile (IPA), a molecular complex composed of two oppositely charged amphiphiles, is a phospholipid mimic which differs from a phospholipid only in the hydrophilic compositions. Here, we utilized molecular dynamics (MD) simulations to compare the bilayer systems composed of phosphatidylcholines (PC) and alkyltrimethylammonium-alkylsulfate IPAs with various alkyl chain lengths. The membrane properties for both liquid-disordered (Ld) and gel (S) phase bilayers were examined via running simulations above and below the main transition temperatures. The electrostatic attraction between the IPA hydrophilic groups leads to a more ordered molecular packing within both S and Ld phase IPA membranes, as revealed by the molecular area, deuterium order parameter, and gauche conformation analyses. Furthermore, IPA bilayers possess a higher area compressibility modulus, molecular tilt modulus, and effective bending rigidity than PC systems. The variation of hydrophilic groups of IPA also leads to fewer hydrogen bonds on the membrane surface and smaller electrostatic potentials for the biomimetic bilayer. The non-covalently linked head groups of IPA further decouple alkyl tilting and surface water retention. The combined results reveal the importance of hydrophilic groups of amphiphiles on modulating the membrane properties, which also provides insights for designs of biomimetic membranes.
Collapse
|
8
|
Hilsch M, Haralampiev I, Müller P, Huster D, Scheidt HA. Membrane properties of hydroxycholesterols related to the brain cholesterol metabolism. Beilstein J Org Chem 2017; 13:720-727. [PMID: 28503207 PMCID: PMC5405690 DOI: 10.3762/bjoc.13.71] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/04/2017] [Indexed: 12/11/2022] Open
Abstract
Compared to cholesterol, hydroxycholesterols contain an additional hydroxy group in the alkyl chain and are able to efficiently cross the brain-blood barrier. Therefore, they are responsible for the sterol transfer between brain and circulation. The current study compares the membrane properties of several hydroxycholesterols with those of cholesterol using 2H NMR spectroscopy, a membrane permeability assay, and fluorescence microscopy experiments. It is shown that hydroxycholesterols do not exert the unique impact on membrane properties characteristic for cholesterol with regard to the influence on lipid chain order, membrane permeability and formation of lateral domains.
Collapse
Affiliation(s)
- Malte Hilsch
- Department of Biology, Humboldt University Berlin, Invalidenstraße 43, D-10115 Berlin, Germany
| | - Ivan Haralampiev
- Department of Biology, Humboldt University Berlin, Invalidenstraße 43, D-10115 Berlin, Germany
| | - Peter Müller
- Department of Biology, Humboldt University Berlin, Invalidenstraße 43, D-10115 Berlin, Germany
| | - Daniel Huster
- Institute for Medical Physics and Biophysics, Leipzig University, Härtelstr. 16–18, D-04107 Leipzig, Germany
| | - Holger A Scheidt
- Institute for Medical Physics and Biophysics, Leipzig University, Härtelstr. 16–18, D-04107 Leipzig, Germany
| |
Collapse
|
9
|
Amaro M, Filipe HAL, Prates Ramalho JP, Hof M, Loura LMS. Fluorescence of nitrobenzoxadiazole (NBD)-labeled lipids in model membranes is connected not to lipid mobility but to probe location. Phys Chem Chem Phys 2016; 18:7042-54. [PMID: 26727975 DOI: 10.1039/c5cp05238f] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Nitrobenzoxadiazole (NBD)-labeled lipids are popular fluorescent membrane probes. However, the understanding of important aspects of the photophysics of NBD remains incomplete, including the observed shift in the emission spectrum of NBD-lipids to longer wavelengths following excitation at the red edge of the absorption spectrum (red-edge excitation shift or REES). REES of NBD-lipids in membrane environments has been previously interpreted as reflecting restricted mobility of solvent surrounding the fluorophore. However, this requires a large change in the dipole moment (Δμ) of NBD upon excitation. Previous calculations of the value of Δμ of NBD in the literature have been carried out using outdated semi-empirical methods, leading to conflicting values. Using up-to-date density functional theory methods, we recalculated the value of Δμ and verified that it is rather small (∼2 D). Fluorescence measurements confirmed that the value of REES is ∼16 nm for 1,2-dioleoyl-sn-glycero-3-phospho-l-serine-N-(NBD) (NBD-PS) in dioleoylphosphatidylcholine vesicles. However, the observed shift is independent of both the temperature and the presence of cholesterol and is therefore insensitive to the mobility and hydration of the membrane. Moreover, red-edge excitation leads to an increased contribution of the decay component with a shorter lifetime, whereas time-resolved emission spectra of NBD-PS displayed an atypical blue shift following excitation. This excludes restrictions to solvent relaxation as the cause of the measured REES and TRES of NBD, pointing instead to the heterogeneous transverse location of probes as the origin of these effects. The latter hypothesis was confirmed by molecular dynamics simulations, from which the calculated heterogeneity of the hydration and location of NBD correlated with the measured fluorescence lifetimes/REES. Globally, our combination of theoretical and experiment-based techniques has led to a considerably improved understanding of the photophysics of NBD and a reinterpretation of its REES in particular.
Collapse
Affiliation(s)
- Mariana Amaro
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 3, 182 23 Prague, Czech Republic.
| | - Hugo A L Filipe
- Centro de Química de Coimbra, Largo D. Dinis, Rua Larga, 3004-535 Coimbra, Portugal. and Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Largo D. Dinis, Rua Larga, 3004-535 Coimbra, Portugal and Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004-504 Coimbra, Portugal
| | - J P Prates Ramalho
- Departamento de Química and Centro de Química de Évora, Escola de Ciências e Tecnologia, Universidade de Évora, Rua Romão Ramalho, 59, 7000-671 Évora, Portugal
| | - Martin Hof
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 3, 182 23 Prague, Czech Republic.
| | - Luís M S Loura
- Centro de Química de Coimbra, Largo D. Dinis, Rua Larga, 3004-535 Coimbra, Portugal. and Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004-504 Coimbra, Portugal and Faculdade de Farmácia, Universidade de Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| |
Collapse
|
10
|
Vogel A, Scheidt HA, Baek DJ, Bittman R, Huster D. Structure and dynamics of the aliphatic cholesterol side chain in membranes as studied by (2)H NMR spectroscopy and molecular dynamics simulation. Phys Chem Chem Phys 2016; 18:3730-8. [PMID: 26762541 DOI: 10.1039/c5cp05084g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cholesterol is an evolutionarily highly optimized molecule particularly known for its ability to condense the phospholipids in cellular membranes. Until recently, the accompanying increase in the chain order of the surrounding phospholipids was attributed to the planar and rigid tetracyclic ring structure of cholesterol. However, detailed investigations of cholesterol's aliphatic side chain demonstrated that this side chain is responsible for approximately half of the condensation effect. Therefore, we investigated the structure and dynamics of the aliphatic side chain of cholesterol using (2)H solid-state nuclear magnetic resonance (NMR) spectroscopy and microsecond timescale all-atom molecular dynamics (MD) simulations in four different model membranes: POPC, DPPC, PSM, and POPC/PSM (1 : 1 mol/mol) and at three different temperatures: 5 °C, 37 °C, and 50 °C. A cholesterol variant, in which 11 hydrogens of the aliphatic side chain were exchanged for deuterium, was used and the respective (2)H NMR spectra confirmed the axially asymmetric rotational diffusion of cholesterol in DPPC and PSM. Furthermore, NMR spectra indicated that some hydrogens showed an unexpected magnetic inequivalency. This finding was confirmed by all-atom molecular dynamics simulations and detailed analysis revealed that the hydrogens of the methylene groups at C22, C23, and C24 are magnetically inequivalent. This inequivalency is caused by steric clashes of the aliphatic side chain with the ring structure of cholesterol as well as the branched C21 methyl group. These excluded volume effects result in reduced conformational flexibility of the aliphatic side chain of cholesterol and explain its high order (order parameter of 0.78 for chain motions) and large contribution to the condensation effect. Additionally, the motional pattern of the side chain becomes highly anisotropic such that it shows larger fluctuations perpendicular to the ring plane of cholesterol with a biaxiality of the distribution of 0.046. Overall, our results shed light on the mechanism how the aliphatic side chain is able to contribute about half of the condensation effect of cholesterol.
Collapse
Affiliation(s)
- Alexander Vogel
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, 04275 Leipzig, Germany.
| | - Holger A Scheidt
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, 04275 Leipzig, Germany.
| | - Dong Jae Baek
- College of Pharmacy and Natural Medicine Research Institute, Mokpo National University, Jeonnam, Republic of Korea and Department of Chemistry and Biochemistry, Queens College of the City University of New York, Flushing, NY 11367-1597, USA
| | - Robert Bittman
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, Flushing, NY 11367-1597, USA
| | - Daniel Huster
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, 04275 Leipzig, Germany.
| |
Collapse
|
11
|
Lin X, Zhang S, Ding H, Levental I, Gorfe AA. The aliphatic chain of cholesterol modulates bilayer interleaflet coupling and domain registration. FEBS Lett 2016; 590:3368-3374. [PMID: 27590031 DOI: 10.1002/1873-3468.12383] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 08/25/2016] [Accepted: 08/29/2016] [Indexed: 11/10/2022]
Abstract
Cholesterol is a necessary component and critical regulator of liquid-ordered membrane domains. However, the structural features that determine its unique physicochemical behaviors are not fully understood. In particular, very little is known about the specific functions of the terminal aliphatic chain of cholesterol, as previous studies have focused mainly on the rigid sterol ring structure and its hydroxyl head. In the current work, we used coarse-grained molecular dynamics simulations to investigate the effect of cholesterol aliphatic chain length on the dynamics and structure of coexisting lipid domains. We found that the aliphatic chain has no appreciable effect on phase separation per se, but it significantly affects the rate of cholesterol flip-flop and intermonolayer interaction. These effects are accompanied by changes in domain dynamics, lateral pressure, and interleaflet coupling. Our study provides useful insight into how biological sterols modulate communication between the outer and inner surfaces of the plasma membrane and, therefore, cellular signaling.
Collapse
Affiliation(s)
- Xubo Lin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Texas 77030, USA
| | - Siya Zhang
- State Key Laboratory of Medical Molecular Biology, School of Basic Medicine, Peking Union Medical College and Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Beijing 100005, China.,Department of Immunology, The University of Texas MD Anderson Cancer Center, Texas 77054, USA
| | - Hui Ding
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Texas 77030, USA.,Department of Respiratory Medicine, Yixing Hospital affiliated Jiangsu University, Jiangsu 214200, China
| | - Ilya Levental
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Texas 77030, USA
| | - Alemayehu A Gorfe
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Texas 77030, USA
| |
Collapse
|
12
|
Shaghaghi M, Chen MT, Hsueh YW, Zuckermann MJ, Thewalt JL. Effect of Sterol Structure on the Physical Properties of 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine Membranes Determined Using (2)H Nuclear Magnetic Resonance. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:7654-7663. [PMID: 27341069 DOI: 10.1021/acs.langmuir.6b01401] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The effect of a series of phytosterols on lipid chain ordering in 1-palmitoyl((2)H31)-2-oleoyl-sn-glycero-3-phosphocholine (POPC-d31) multibilayer vesicles was examined by (2)H NMR spectroscopy at 25 °C. These results, along with existing data for other sterols, indicate that the ordering power of sterols in POPC-d31 depends on subtle aspects of sterol structure. Cholesterol, 7-dehydrocholesterol (7-DHC), campesterol, β-sitosterol, ergosterol, brassicasterol, and stigmasterol all increase the lipid chain order as sterol concentration is increased. However, saturation of the ordering occurs at different sterol concentrations for ergosterol (as previously reported), brassicasterol, β-sitosterol, and stigmasterol. Here our interest lies in finding which part of the sterol structure is responsible for the observed saturation of the palmitoyl chain order as a function of sterol concentration. In particular, we propose that the saturation of the ordering of POPC-d31/brassicasterol and POPC-d31/stigmasterol membranes at quite low sterol concentrations is due to the presence of a double bond at C22. We also discuss how the structural differences between the sterols affect their ability to intercalate between the POPC acyl chains. Furthermore, the effective solubility of sterols in POPC is discussed in relation to the dependence of maximum POPC-d31 chain order vs sterol concentration.
Collapse
Affiliation(s)
| | - Mei-Ting Chen
- Department of Physics, National Central University , Jung-Li 32001, Taiwan
| | - Ya-Wei Hsueh
- Department of Physics, National Central University , Jung-Li 32001, Taiwan
| | | | | |
Collapse
|
13
|
do Canto AMTM, Robalo JR, Santos PD, Carvalho AJP, Ramalho JPP, Loura LMS. Diphenylhexatriene membrane probes DPH and TMA-DPH: A comparative molecular dynamics simulation study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2647-2661. [PMID: 27475296 DOI: 10.1016/j.bbamem.2016.07.013] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/05/2016] [Accepted: 07/25/2016] [Indexed: 10/21/2022]
Abstract
Fluorescence spectroscopy and microscopy have been utilized as tools in membrane biophysics for decades now. Because phospholipids are non-fluorescent, the use of extrinsic membrane probes in this context is commonplace. Among the latter, 1,6-diphenylhexatriene (DPH) and its trimethylammonium derivative (TMA-DPH) have been extensively used. It is widely believed that, owing to its additional charged group, TMA-DPH is anchored at the lipid/water interface and reports on a bilayer region that is distinct from that of the hydrophobic DPH. In this study, we employ atomistic MD simulations to characterize the behavior of DPH and TMA-DPH in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and POPC/cholesterol (4:1) bilayers. We show that although the dynamics of TMA-DPH in these membranes is noticeably more hindered than that of DPH, the location of the average fluorophore of TMA-DPH is only ~3-4Å more shallow than that of DPH. The hindrance observed in the translational and rotational motions of TMA-DPH compared to DPH is mainly not due to significant differences in depth, but to the favorable electrostatic interactions of the former with electronegative lipid atoms instead. By revealing detailed insights on the behavior of these two probes, our results are useful both in the interpretation of past work and in the planning of future experiments using them as membrane reporters.
Collapse
Affiliation(s)
- António M T M do Canto
- Centro de Química de Évora e Departamento de Química, Escola de Ciências e Tecnologia, Colégio Luís Verney, Rua Romão Ramalho 59, P-7002-554 Évora, Portugal
| | - João R Robalo
- Centro de Química de Évora e Departamento de Química, Escola de Ciências e Tecnologia, Colégio Luís Verney, Rua Romão Ramalho 59, P-7002-554 Évora, Portugal; Theory and Bio-Systems Department, Max Planck Institute of Colloids and Interfaces, Wissenschaftspark Golm, D-14424 Potsdam, Germany
| | - Patrícia D Santos
- Centro de Química de Évora e Departamento de Química, Escola de Ciências e Tecnologia, Colégio Luís Verney, Rua Romão Ramalho 59, P-7002-554 Évora, Portugal
| | - Alfredo J Palace Carvalho
- Centro de Química de Évora e Departamento de Química, Escola de Ciências e Tecnologia, Colégio Luís Verney, Rua Romão Ramalho 59, P-7002-554 Évora, Portugal
| | - J P Prates Ramalho
- Centro de Química de Évora e Departamento de Química, Escola de Ciências e Tecnologia, Colégio Luís Verney, Rua Romão Ramalho 59, P-7002-554 Évora, Portugal
| | - Luís M S Loura
- Faculdade de Farmácia, Universidade de Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, P-3000-548 Coimbra, Portugal; Centro de Química de Coimbra, Largo D. Dinis, Rua Larga, P-3004-535 Coimbra, Portugal.
| |
Collapse
|