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Billah MM, Ahmed M, Islam MZ, Yamazaki M. Processes and mechanisms underlying burst of giant unilamellar vesicles induced by antimicrobial peptides and compounds. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184330. [PMID: 38679311 DOI: 10.1016/j.bbamem.2024.184330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 04/05/2024] [Accepted: 04/23/2024] [Indexed: 05/01/2024]
Abstract
To clarify the damage of lipid bilayer region in bacterial cell membrane caused by antimicrobial peptides (AMPs) and antimicrobial compounds (AMCs), their interactions with giant unilamellar vesicles (GUVs) of various lipid compositions have been examined. The findings revealed two main causes for the leakage: nanopore formation in the membrane and burst of GUVs. Although GUV burst has been explained previously based on the carpet model, the supporting evidence is limited. In this review, to better clarify the mechanism of GUV burst by AMPs, AMCs, and other membrane-active peptides, we described current knowledge of the conditions, characteristics, and detailed processes of GUV burst and the changes in the shape of the GUVs during burst. We identified several physical factors that affect GUV burst, such as membrane tension, electrostatic interaction, structural changes of GUV membrane such as membrane folding, and oil in the membrane. We also clarified one of the physical mechanisms underlying the instability of lipid bilayers that are associated with leakage in the carpet model. Based on these results, we propose a mechanism underlying some types of GUV burst induced by these substances: the growth of a nanopore to a micropore, resulting in GUV burst.
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Affiliation(s)
- Md Masum Billah
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan; Department of Physics, Jashore University and Science and Technology, Jashore 7408, Bangladesh
| | - Marzuk Ahmed
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Md Zahidul Islam
- Nanomaterials Research Division, Research Institute of Electronics, Shizuoka University, Shizuoka 422-8529, Japan
| | - Masahito Yamazaki
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan; Nanomaterials Research Division, Research Institute of Electronics, Shizuoka University, Shizuoka 422-8529, Japan; Department of Physics, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan.
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2
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Ahmed M, Islam MZ, Billah MM, Yamazaki M. Effect of Phosphatidylethanolamine on Pore Formation Induced by the Antimicrobial Peptide PGLa. J Phys Chem B 2024; 128:2684-2696. [PMID: 38450565 DOI: 10.1021/acs.jpcb.3c08098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Most antimicrobial peptides (AMPs) induce pore formation and a burst of lipid bilayers and plasma membranes. This causes severe leakage of the internal contents and cell death. The AMP PGLa forms nanopores in giant unilamellar vesicles (GUVs) comprising dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylglycerol (DOPG). We here elucidated the effect of the line tension of a prepore rim on PGLa-induced nanopore formation by investigating the interaction of PGLa with single GUVs comprising dioleoylphosphatidylethanolamine (DOPE)/DOPG (6:4) in buffer using the single GUV method. We found that PGLa forms nanopores in the GUV membrane, which evolved into a local burst and burst of GUVs. The rate of pore formation in DOPE/DOPG-GUVs was smaller than that in DOPC/DOPG-GUVs. PGLa is located only in the outer leaflet of a GUV bilayer just before a fluorescent probe AF647 leakage from the inside, indicating that this asymmetric distribution induces nanopore formation. PGLa-induced local burst and burst of GUVs were observed at 10 ms-time resolution. After nanopore formation started, dense particles and small vesicles appeared in the GUVs, followed by a decrease in the GUV diameter. The GUV was finally converted into smaller GUV or lipid membrane aggregates. We discuss the mechanisms of PGLa-induced nanopore formation and its direct evolution to a GUV burst.
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Affiliation(s)
- Marzuk Ahmed
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Md Zahidul Islam
- Nanomaterials Research Division, Research Institute of Electronics, Shizuoka University, Shizuoka 422-8529, Japan
| | - Md Masum Billah
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Masahito Yamazaki
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
- Nanomaterials Research Division, Research Institute of Electronics, Shizuoka University, Shizuoka 422-8529, Japan
- Department of Physics, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan
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3
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M N, Vincent O, Sarangi BR, Kumar B. Kinetics of Nisin-Induced Pore Formation in Giant Unilamellar Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:11231-11237. [PMID: 37526639 DOI: 10.1021/acs.langmuir.3c00515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
We have studied the kinetics of pore formation in giant unilamellar vesicles (GUV) with the antimicrobial peptide nisin. The role of charged lipid composition in the rate of pore formation by nisin in the vesicle membrane is investigated using fluorescence microscopy. We propose a model and obtain an analytical expression for the variation in the fluorescence intensity of a GUV as a function of time. We find that the analytical equation fits well to the experimental data, and the membrane surface potential can be estimated from the fit parameters. We further show that the formation of multiple pores on the vesicle membrane is affected by the charged lipid composition of the membrane.
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Affiliation(s)
- Nithya M
- Department of Physics, Central University of Karnataka, Kadaganchi, Karnataka 585367, India
| | - Olivia Vincent
- Department of Physics, Indian Institute of Technology Palakkad, Palakkad, Kerala 678623, India
| | - Bibhu Ranjan Sarangi
- Department of Physics, Indian Institute of Technology Palakkad, Palakkad, Kerala 678623, India
- Department of Biological Science and Engineering, Indian Institute of Technology Palakkad, Palakkad, Kerala 678557, India
| | - Bharat Kumar
- Department of Physics, Central University of Karnataka, Kadaganchi, Karnataka 585367, India
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4
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Dai H, Peterson KL, Flatten KS, Meng XW, Venkatachalam A, Correia C, Ramirez-Alvarado M, Pang YP, Kaufmann SH. A BAK subdomain that binds mitochondrial lipids selectively and releases cytochrome C. Cell Death Differ 2023; 30:794-808. [PMID: 36376382 PMCID: PMC9984382 DOI: 10.1038/s41418-022-01083-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 10/20/2022] [Accepted: 10/28/2022] [Indexed: 11/16/2022] Open
Abstract
How BAK and BAX induce mitochondrial outer membrane (MOM) permeabilization (MOMP) during apoptosis is incompletely understood. Here we have used molecular dynamics simulations, surface plasmon resonance, and assays for membrane permeabilization in vitro and in vivo to assess the structure and function of selected BAK subdomains and their derivatives. Results of these studies demonstrate that BAK helical regions α5 and α6 bind the MOM lipid cardiolipin. While individual peptides corresponding to these helical regions lack the full biological activity of BAK, tandem peptides corresponding to α4-α5, α5-α6, or α6-α7/8 can localize exogenous proteins to mitochondria, permeabilize liposomes composed of MOM lipids, and cause MOMP in the absence of the remainder of the BAK protein. Importantly, the ability of these tandem helices to induce MOMP under cell-free conditions is diminished by mutations that disrupt the U-shaped helix-turn-helix structure of the tandem peptides or decrease their lipid binding. Likewise, BAK-induced apoptosis in intact cells is diminished by CLS1 gene interruption, which decreases mitochondrial cardiolipin content, or by BAK mutations that disrupt the U-shaped tandem peptide structure or diminish lipid binding. Collectively, these results suggest that BAK structural rearrangements during apoptosis might mobilize helices involved in specific protein-lipid interactions that are critical for MOMP.
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Affiliation(s)
- Haiming Dai
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA.
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA.
- Anhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, China.
- Hefei Cancer Hospital, Chinese Academy of Sciences, Hefei, 230031, China.
| | - Kevin L Peterson
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA
| | - Karen S Flatten
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA
| | - X Wei Meng
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
| | | | - Cristina Correia
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
| | | | - Yuan-Ping Pang
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
| | - Scott H Kaufmann
- Division of Oncology Research, Mayo Clinic, Rochester, MN, 55905, USA.
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA.
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5
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Barisch C, Holthuis JCM, Cosentino K. Membrane damage and repair: a thin line between life and death. Biol Chem 2023; 404:467-490. [PMID: 36810295 DOI: 10.1515/hsz-2022-0321] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/03/2023] [Indexed: 02/24/2023]
Abstract
Bilayered membranes separate cells from their surroundings and form boundaries between intracellular organelles and the cytosol. Gated transport of solutes across membranes enables cells to establish vital ion gradients and a sophisticated metabolic network. However, an advanced compartmentalization of biochemical reactions makes cells also particularly vulnerable to membrane damage inflicted by pathogens, chemicals, inflammatory responses or mechanical stress. To avoid potentially lethal consequences of membrane injuries, cells continuously monitor the structural integrity of their membranes and readily activate appropriate pathways to plug, patch, engulf or shed the damaged membrane area. Here, we review recent insights into the cellular mechanisms that underly an effective maintenance of membrane integrity. We discuss how cells respond to membrane lesions caused by bacterial toxins and endogenous pore-forming proteins, with a primary focus on the intimate crosstalk between membrane proteins and lipids during wound formation, detection and elimination. We also discuss how a delicate balance between membrane damage and repair determines cell fate upon bacterial infection or activation of pro-inflammatory cell death pathways.
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Affiliation(s)
- Caroline Barisch
- Molecular Infection Biology Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
| | - Joost C M Holthuis
- Molecular Cell Biology Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
| | - Katia Cosentino
- Molecular Cell Biophysics Division, Department of Biology and Center of Cellular Nanoanalytics, Osnabrück University, D-49076 Osnabrück, Germany
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6
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Flores‐Romero H, Hohorst L, John M, Albert M, King LE, Beckmann L, Szabo T, Hertlein V, Luo X, Villunger A, Frenzel LP, Kashkar H, Garcia‐Saez AJ. BCL-2-family protein tBID can act as a BAX-like effector of apoptosis. EMBO J 2022; 41:e108690. [PMID: 34931711 PMCID: PMC8762556 DOI: 10.15252/embj.2021108690] [Citation(s) in RCA: 76] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 11/14/2021] [Accepted: 11/22/2021] [Indexed: 12/26/2022] Open
Abstract
During apoptosis, the BCL-2-family protein tBID promotes mitochondrial permeabilization by activating BAX and BAK and by blocking anti-apoptotic BCL-2 members. Here, we report that tBID can also mediate mitochondrial permeabilization by itself, resulting in release of cytochrome c and mitochondrial DNA, caspase activation and apoptosis even in absence of BAX and BAK. This previously unrecognized activity of tBID depends on helix 6, homologous to the pore-forming regions of BAX and BAK, and can be blocked by pro-survival BCL-2 proteins. Importantly, tBID-mediated mitochondrial permeabilization independent of BAX and BAK is physiologically relevant for SMAC release in the immune response against Shigella infection. Furthermore, it can be exploited to kill leukaemia cells with acquired venetoclax resistance due to lack of active BAX and BAK. Our findings define tBID as an effector of mitochondrial permeabilization in apoptosis and provide a new paradigm for BCL-2 proteins, with implications for anti-bacterial immunity and cancer therapy.
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Affiliation(s)
- Hector Flores‐Romero
- Institute for GeneticsUniversity of CologneCologneGermany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
- Interfaculty Institute of BiochemistryEberhard‐Karls‐Universität TübingenTübingenGermany
| | - Lisa Hohorst
- Institute for GeneticsUniversity of CologneCologneGermany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Malina John
- Interfaculty Institute of BiochemistryEberhard‐Karls‐Universität TübingenTübingenGermany
| | - Marie‐Christine Albert
- Institute for Molecular Immunology, and Center for Molecular Medicine Cologne (CMMC)Faculty of MedicineUniversity Hospital of CologneUniversity of CologneCologneGermany
| | - Louise E King
- Institute for GeneticsUniversity of CologneCologneGermany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Laura Beckmann
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
- Department I of Internal MedicineUniversity Hospital of CologneCologneGermany
- Center of Integrated Oncology ABCDUniversity Hospital of CologneCologneGermany
| | - Tamas Szabo
- Division of Developmental ImmunologyBiocenterMedical University of InnsbruckInnsbruckAustria
| | - Vanessa Hertlein
- Interfaculty Institute of BiochemistryEberhard‐Karls‐Universität TübingenTübingenGermany
- Present address:
Children Cancer Research Institute (CCRI)ViennaAustria
| | - Xu Luo
- Eppley Institute for Research in Cancer and Allied DiseasesFred & Pamela Buffett Cancer CenterUniversity of Nebraska Medical CenterOmahaMEUSA
- Department of Pathology and MicrobiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Andreas Villunger
- Division of Developmental ImmunologyBiocenterMedical University of InnsbruckInnsbruckAustria
- CeMM Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
- Ludwig Boltzmann Institute for Rare and Undiagnosed DiseasesViennaAustria
| | - Lukas P Frenzel
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
- Department I of Internal MedicineUniversity Hospital of CologneCologneGermany
- Center of Integrated Oncology ABCDUniversity Hospital of CologneCologneGermany
| | - Hamid Kashkar
- Institute for Molecular Immunology, and Center for Molecular Medicine Cologne (CMMC)Faculty of MedicineUniversity Hospital of CologneUniversity of CologneCologneGermany
| | - Ana J Garcia‐Saez
- Institute for GeneticsUniversity of CologneCologneGermany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
- Interfaculty Institute of BiochemistryEberhard‐Karls‐Universität TübingenTübingenGermany
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7
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Hausig-Punke F, Richter F, Hoernke M, Brendel JC, Traeger A. Tracking the Endosomal Escape: A Closer Look at Calcein and Related Reporters. Macromol Biosci 2022; 22:e2200167. [PMID: 35933579 DOI: 10.1002/mabi.202200167] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 07/19/2022] [Indexed: 11/11/2022]
Abstract
Crossing the cellular membrane and delivering active pharmaceuticals or biologicals into the cytosol of cells is an essential step in the development of nanomedicines. One of the most important intracellular processes regarding the cellular uptake of biologicals is the endolysosomal pathway. Sophisticated nanocarriers have been developed overcoming a major hurdle, the endosomal entrapment, and delivering their cargo to the required site of action. In parallel, in vitro assays have been established analyzing the performance of these nanocarriers. Among them, the release of the membrane-impermeable dye calcein has become a popular and straightforward method. It is accessible for most researchers worldwide, allows for rapid conclusions about the release potential, and enables the study of release mechanisms. This review is intended to provide an overview and guidance for scientists applying the calcein release assay. It comprises a survey of several applications in the study of endosomal escape, considerations of potential pitfalls, challenges and limitations of the assay, and a brief summary of complementary methods. Based on this review, we hope to encourage further research groups to take advantage of the calcein release assay for their own purposes and help to create a database for more efficient cross-correlations between nanocarriers. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Franziska Hausig-Punke
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
| | - Friederike Richter
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
| | - Maria Hoernke
- Chemistry and Pharmacy, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 9, 79104, Freiburg i.Br., Germany
| | - Johannes C Brendel
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
| | - Anja Traeger
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
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8
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Pore-forming proteins: From defense factors to endogenous executors of cell death. Chem Phys Lipids 2020; 234:105026. [PMID: 33309552 DOI: 10.1016/j.chemphyslip.2020.105026] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 12/07/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023]
Abstract
Pore-forming proteins (PFPs) and small antimicrobial peptides (AMPs) represent a large family of molecules with the common ability to punch holes in cell membranes to alter their permeability. They play a fundamental role as infectious bacteria's defensive tools against host's immune system and as executors of endogenous machineries of regulated cell death in eukaryotic cells. Despite being highly divergent in primary sequence and 3D structure, specific folds of pore-forming domains have been conserved. In fact, pore formation is considered an ancient mechanism that takes place through a general multistep process involving: membrane partitioning and insertion, oligomerization and pore formation. However, different PFPs and AMPs assemble and form pores following different mechanisms that could end up either in the formation of protein-lined or protein-lipid pores. In this review, we analyze the current findings in the mechanism of action of different PFPs and AMPs that support a wide role of membrane pore formation in nature. We also provide the newest insights into the development of state-of-art techniques that have facilitated the characterization of membrane pores. To understand the physiological role of these peptides/proteins or develop clinical applications, it is essential to uncover the molecular mechanism of how they perforate membranes.
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9
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Martínez-Calle M, Parra-Ortiz E, Cruz A, Olmeda B, Pérez-Gil J. Towards the Molecular Mechanism of Pulmonary Surfactant Protein SP-B: At the Crossroad of Membrane Permeability and Interfacial Lipid Transfer. J Mol Biol 2020; 433:166749. [PMID: 33309854 DOI: 10.1016/j.jmb.2020.166749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/14/2020] [Accepted: 12/03/2020] [Indexed: 11/17/2022]
Abstract
Pulmonary surfactant is a lipid-protein complex that coats the alveolar air-liquid interface, enabling the proper functioning of lung mechanics. The hydrophobic surfactant protein SP-B, in particular, plays an indispensable role in promoting the rapid adsorption of phospholipids into the interface. For this, formation of SP-B ring-shaped assemblies seems to be important, as oligomerization could be required for the ability of the protein to generate membrane contacts and to mediate lipid transfer among surfactant structures. SP-B, together with the other hydrophobic surfactant protein SP-C, also promotes permeability of surfactant membranes to polar molecules although the molecular mechanisms underlying this property, as well as its relevance for the surface activity of the protein, remain undefined. In this work, the contribution of SP-B and SP-C to surfactant membrane permeability has been further investigated, by evaluation of the ability of differently-sized fluorescent polar probes to permeate through giant vesicles with different lipid/protein composition. Our results are consistent with the generation by SP-B of pores with defined size in surfactant membranes. Furthermore, incubation of surfactant with an anti-SP-B antibody not only blocked membrane permeability but also affected lipid transfer into the air-water interface, as observed in a captive bubble surfactometer device. Our findings include the identification of SP-C and anionic phospholipids as modulators required for maintaining native-like permeability features in pulmonary surfactant membranes. Proper permeability through membrane assemblies could be crucial to complement the overall role of surfactant in maintaining alveolar equilibrium, beyond its biophysical function in stabilizing the respiratory air-liquid interface.
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Affiliation(s)
- Marta Martínez-Calle
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain; Research Institute "Hospital 12 de Octubre (imas12)", Complutense University, Madrid, Spain
| | - Elisa Parra-Ortiz
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain
| | - Antonio Cruz
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain; Research Institute "Hospital 12 de Octubre (imas12)", Complutense University, Madrid, Spain
| | - Barbara Olmeda
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain; Research Institute "Hospital 12 de Octubre (imas12)", Complutense University, Madrid, Spain.
| | - Jesús Pérez-Gil
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain; Research Institute "Hospital 12 de Octubre (imas12)", Complutense University, Madrid, Spain
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10
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Flores‐Romero H, Ros U, Garcia‐Saez AJ. Pore formation in regulated cell death. EMBO J 2020; 39:e105753. [PMID: 33124082 PMCID: PMC7705454 DOI: 10.15252/embj.2020105753] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/13/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022] Open
Abstract
The discovery of alternative signaling pathways that regulate cell death has revealed multiple strategies for promoting cell death with diverse consequences at the tissue and organism level. Despite the divergence in the molecular components involved, membrane permeabilization is a common theme in the execution of regulated cell death. In apoptosis, the permeabilization of the outer mitochondrial membrane by BAX and BAK releases apoptotic factors that initiate the caspase cascade and is considered the point of no return in cell death commitment. Pyroptosis and necroptosis also require the perforation of the plasma membrane at the execution step, which involves Gasdermins in pyroptosis, and MLKL in the case of necroptosis. Although BAX/BAK, Gasdermins and MLKL share certain molecular features like oligomerization, they form pores in different cellular membranes via distinct mechanisms. Here, we compare and contrast how BAX/BAK, Gasdermins, and MLKL alter membrane permeability from a structural and biophysical perspective and discuss the general principles of membrane permeabilization in the execution of regulated cell death.
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Affiliation(s)
- Hector Flores‐Romero
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Uris Ros
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Ana J Garcia‐Saez
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
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11
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Flores-Romero H, Ros U, García-Sáez AJ. A lipid perspective on regulated cell death. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2019; 351:197-236. [PMID: 32247580 DOI: 10.1016/bs.ircmb.2019.11.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lipids are fundamental to life as structural components of cellular membranes and for signaling. They are also key regulators of different cellular processes such as cell division, proliferation, and death. Regulated cell death (RCD) requires the engagement of lipids and lipid metabolism for the initiation and execution of its killing machinery. The permeabilization of lipid membranes is a hallmark of RCD that involves, for each kind of cell death, a unique lipid profile. While the permeabilization of the mitochondrial outer membrane allows the release of apoptotic factors to the cytosol during apoptosis, permeabilization of the plasma membrane facilitates the release of intracellular content in other nonapoptotic types of RCD like necroptosis and ferroptosis. Lipids and lipid membranes are important accessory molecules required for the activation of protein executors of cell death such as BAX in apoptosis and MLKL in necroptosis. Peroxidation of membrane phospholipids and the subsequent membrane destabilization is a prerequisite to ferroptosis. Here, we discuss how lipids are essential players in apoptosis, the most common form of RCD, and also their role in necroptosis and ferroptosis. Altogether, we aim to highlight the contribution of lipids and membrane dynamics in cell death regulation.
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Affiliation(s)
- Hector Flores-Romero
- Interfaculty Institute of Biochemistry, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
| | - Uris Ros
- Interfaculty Institute of Biochemistry, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, Eberhard-Karls-Universität Tübingen, Tübingen, Germany.
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12
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Stulz A, Vogt A, Saar JS, Akil L, Lienkamp K, Hoernke M. Quantified Membrane Permeabilization Indicates the Lipid Selectivity of Membrane-Active Antimicrobials. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16366-16376. [PMID: 31710807 DOI: 10.1021/acs.langmuir.9b01849] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Most antimicrobial peptides (AMPs) and their synthetic mimics (SMAMPs) are thought to act by permeabilizing cell membranes. For antimicrobial therapy, selectivity for pathogens over mammalian cells is a key requirement. Understanding membrane selectivity is thus essential for designing AMPs and SMAMPs to complement classical antibiotics in the future. This study focuses on membrane permeabilization induced by SMAMPs and their selectivity for membranes with different lipid compositions. We measure release and fluorescence lifetime of a self-quenching dye in lipid vesicles. Apart from the dose-response, we quantify the strength of individual leakage events, and, employing cumulative kinetics, categorize permeabilization behavior. We propose that differing selectivities in a series of SMAMPs arise from a combination of the effect of the antimicrobial agent and the susceptibility of the membrane (with a given lipid composition) for certain types of leakage behavior. The unselective and hemolytic SMAMP is found to act mainly by the asymmetry stress mechanism, mediated by hydrophobic insertion of SMAMPs into lipid layers. The more selective SMAMPs induced leakage events occurring stochastically over several hours. Lipid intrinsic properties might additionally amplify the efficiency of leakage events. Leakage behavior changes with both the design of the SMAMP and the lipid composition of the membrane. Understanding how leakage behavior contributes to the selectivity and activity of antimicrobial agents will aid the design and screening of antimicrobials. An understanding of the underlying processes facilitates the comparison of membrane permeabilization across in vitro and in vivo assays.
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Affiliation(s)
- Anja Stulz
- Pharmaceutical Technology and Biopharmacy , Albert-Ludwigs-Universität , Freiburg i.Br ., Germany
| | - Annika Vogt
- Pharmaceutical Technology and Biopharmacy , Albert-Ludwigs-Universität , Freiburg i.Br ., Germany
- Faculty of Applied Chemistry , Reutlingen University , Reutlingen , Germany
| | - Julia Selina Saar
- Department of Microsystems Engineering (IMTEK) and Freiburg Center for Interactive Materials and Bioinspired Technologies (FIT) , Albert-Ludwigs-Universität , Freiburg i.Br ., Germany
| | - Larissa Akil
- Pharmaceutical Technology and Biopharmacy , Albert-Ludwigs-Universität , Freiburg i.Br ., Germany
| | - Karen Lienkamp
- Department of Microsystems Engineering (IMTEK) and Freiburg Center for Interactive Materials and Bioinspired Technologies (FIT) , Albert-Ludwigs-Universität , Freiburg i.Br ., Germany
| | - Maria Hoernke
- Pharmaceutical Technology and Biopharmacy , Albert-Ludwigs-Universität , Freiburg i.Br ., Germany
- BIOSS Centre for Biological Signalling Studies , Albert-Ludwigs-Universität , Freiburg i.Br ., Germany
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13
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Arribas Perez M, Moriones OH, Bastús NG, Puntes V, Nelson A, Beales PA. Mechanomodulation of Lipid Membranes by Weakly Aggregating Silver Nanoparticles. Biochemistry 2019; 58:4761-4773. [DOI: 10.1021/acs.biochem.9b00390] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marcos Arribas Perez
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
| | - Oscar H. Moriones
- Institut Català de Nanociència y Nanotecnologia (ICN2), Campus UAB, 08193 Bellaterra, Barcelona, Spain
- Universitat Autonòma de Barcelona (UAB), Campus UAB, 08193 Bellaterra, Barcelona, Spain
| | - Neus G. Bastús
- Institut Català de Nanociència y Nanotecnologia (ICN2), Campus UAB, 08193 Bellaterra, Barcelona, Spain
| | - Victor Puntes
- Institut Català de Nanociència y Nanotecnologia (ICN2), Campus UAB, 08193 Bellaterra, Barcelona, Spain
- Universitat Autonòma de Barcelona (UAB), Campus UAB, 08193 Bellaterra, Barcelona, Spain
- Vall d’Hebron Institut de Recerca (VHIR), 08035 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| | - Andrew Nelson
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
| | - Paul A. Beales
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
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14
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Spontaneous and Stress-Induced Pore Formation in Membranes: Theory, Experiments and Simulations. J Membr Biol 2019; 252:241-260. [PMID: 31363808 DOI: 10.1007/s00232-019-00083-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/17/2019] [Indexed: 10/26/2022]
Abstract
The large plasticity, dynamics and adaptability of biological membranes allow different modes of intrinsic and inducible permeability. These phenomena are of physiological importance for a number of natural functions related to cell death and can also be manipulated artificially for practical purposes like gene transfer, drug delivery, prevention of infections or anticancer therapy. For these advances to develop in a controllable and specific way, we need a sufficient understanding of the membrane permeability phenomena. Since the formulation of early concepts of pore formation, there has been an enormous effort to describe membrane permeability by using theory, simulations and experiments. A major breakthrough has come recently through theoretical developments that allow building continuous trajectories of pore formation both in the absence and presence of stress conditions. The new model provides a coherent quantitative view of membrane permeabilization, useful to test the impact of known lipid properties, make predictions and postulate specific pore intermediates that can be studied by simulations. For example, this theory predicts unprecedented dependencies of the line tension on the pore radius and on applied lateral tension which explain previous puzzling results. In parallel, important concepts have also come from molecular dynamics simulations, of which the role of water for membrane permeabilization is of special interest. These advances open new challenges and perspectives for future progress in the study of membrane permeability, as experiments and simulations will need to test the theoretical predictions, while theory achieves new refinements that provide a physical ground for observations.
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15
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Dhuriya YK, Sharma D, Naik AA. Cellular demolition: Proteins as molecular players of programmed cell death. Int J Biol Macromol 2019; 138:492-503. [PMID: 31330212 DOI: 10.1016/j.ijbiomac.2019.07.113] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 06/25/2019] [Accepted: 07/19/2019] [Indexed: 12/11/2022]
Abstract
Apoptosis, a well-characterized and regulated cell death programme in eukaryotes plays a fundamental role in developing or later-life periods to dispose of unwanted cells to maintain typical tissue architecture, homeostasis in a spatiotemporal manner. This silent cellular death occurs without affecting any neighboring cells/tissue and avoids triggering of immunological response. Furthermore, diminished forms of apoptosis result in cancer and autoimmune diseases, whereas unregulated apoptosis may also lead to the development of a myriad of neurodegenerative diseases. Unraveling the mechanistic events in depth will provide new insights into understanding physiological control of apoptosis, pathological consequences of abnormal apoptosis and development of novel therapeutics for diseases. Here we provide a brief overview of molecular players of programmed cell death with discussion on the role of caspases, modifications, ubiquitylation in apoptosis, removal of the apoptotic body and its relevance to diseases.
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Affiliation(s)
- Yogesh Kumar Dhuriya
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, Lucknow 226 001, India
| | - Divakar Sharma
- Department of Biochemistry, National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Tajganj, Agra, India; Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India.
| | - Aijaz A Naik
- Neurology, School of Medicine, University of Virginia, Charlottesville 22908, United States of America
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16
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Hasan M, Yamazaki M. Elementary Processes and Mechanisms of Interactions of Antimicrobial Peptides with Membranes-Single Giant Unilamellar Vesicle Studies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1117:17-32. [PMID: 30980351 DOI: 10.1007/978-981-13-3588-4_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
To elucidate the mechanisms of action of antimicrobial peptides (AMPs) and to develop de novo designed peptides with activities similar to those of AMPs, it is essential to elucidate the detailed processes of AMP interactions with plasma membranes of bacterial and fungal cells and model membranes (lipid bilayers). In this mini-review, we summarize the present state of knowledge of the interactions of AMPs with lipid vesicles obtained using the single giant unilamellar vesicle (GUV) method. Currently, three modes of action of AMPs on GUVs have been defined. The elementary processes of interactions of AMPs with lipid vesicles revealed by the single GUV method, and the advantages of this technique, are described and discussed. For example, the single GUV method can be used to determine rate constants of AMP-induced pore formation or local rupture and membrane permeation of internal contents through the pore or the local rupture, the transbilayer movement of lipids, and the relationship between the location of AMPs and pore formation. Effects of membrane tension and of asymmetric lipid packing in the bilayer on AMP-induced pore formation also are described. On the basis of these data, we discuss the present state of understanding of the interaction of AMPs with lipid bilayers and future prospects for AMP studies.
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Affiliation(s)
- Moynul Hasan
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka, Japan
| | - Masahito Yamazaki
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka, Japan.
- Nanomaterials Research Division, Research Institute of Electronics, Shizuoka University, Shizuoka, Japan.
- Department of Physics, Graduate School of Science, Shizuoka University, Shizuoka, Japan.
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17
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Abstract
Bacterial membranes represent an attractive target for the design of new antibiotics to combat widespread bacterial resistance to traditional inhibitor-based antibiotics. Understanding how antimicrobial peptides (AMPs) and other membrane-active agents attack membranes could facilitate the design of new, effective antimicrobials. AMPs, which are small, gene-encoded host defense proteins, offer a promising basis for the study of membrane-active antimicrobial agents. These peptides are cationic and amphipathic, spontaneously binding to bacterial membranes and inducing transmembrane permeability to small molecules. Yet there are often confusions surrounding the details of the molecular mechanisms of AMPs. Following the doctrine of structure-function relationship, AMPs are often viewed as the molecular scaffolding of pores in membranes. Instead we believe that the full mechanism of AMPs is understandable if we consider the interactions of AMPs with the whole membrane domain, where interactions induce structural transformations of the entire membrane, rather than forming localized molecular structures. We believe that it is necessary to consider the entire soft matter peptide-membrane system as it evolves through several distinct states. Accordingly, we have developed experimental techniques to investigate the state and structure of the membrane as a function of the bound peptide to lipid ratio, exactly as AMPs in solution progressively bind to the membrane and induce structural changes to the entire system. The results from these studies suggest that global interactions of AMPs with the membrane domain are of fundamental importance to understanding the antimicrobial mechanisms of AMPs.
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18
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Hasan M, Karal MAS, Levadnyy V, Yamazaki M. Mechanism of Initial Stage of Pore Formation Induced by Antimicrobial Peptide Magainin 2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3349-3362. [PMID: 29446954 DOI: 10.1021/acs.langmuir.7b04219] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Antimicrobial peptide magainin 2 forms pores in lipid bilayers, a property that is considered the main cause of its bactericidal activity. Recent data suggest that tension or stretching of the inner monolayer plays an important role in magainin 2-induced pore formation in lipid bilayers. Here, to elucidate the mechanism of magainin 2-induced pore formation, we investigated the effect on pore formation of asymmetric lipid distribution in two monolayers. First, we developed a method to prepare giant unilamellar vesicles (GUVs) composed of dioleoylphosphatidylglycerol (DOPG), dioleoylphosphatidylcholine (DOPC), and lyso-PC (LPC) in the inner monolayer and of DOPG/DOPC in the outer monolayer. We consider that in these GUVs, the lipid packing in the inner monolayer was larger than that in the outer monolayer. Next, we investigated the interaction of magainin 2 with these GUVs with an asymmetric distribution of LPC using the single GUV method, and found that the rate constant of magainin 2-induced pore formation, kp, decreased with increasing LPC concentration in the inner monolayer. We constructed a quantitative model of magainin 2-induced pore formation, whereby the binding of magainin 2 to the outer monolayer of a GUV induces stretching of the inner monolayer, causing pore formation. A theoretical equation defining kp as a function of magainin 2 surface concentration, X, reasonably explains the experimental relationship between kp and X. This model quantitatively explains the effect on kp of the LPC concentration in the inner monolayer. On the basis of these results, we discuss the mechanism of the initial stage of magainin 2-induced pore formation.
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Affiliation(s)
- Moynul Hasan
- Integrated Bioscience Section, Graduate School of Science and Technology , Shizuoka University , Shizuoka 422-8529 , Japan
| | - Mohammad Abu Sayem Karal
- Integrated Bioscience Section, Graduate School of Science and Technology , Shizuoka University , Shizuoka 422-8529 , Japan
| | - Victor Levadnyy
- Integrated Bioscience Section, Graduate School of Science and Technology , Shizuoka University , Shizuoka 422-8529 , Japan
- Theoretical Problem Center of Physico-Chemical Pharmacology , Russian Academy of Sciences , Kosugina, 4 , 117977 Moscow , Russia
| | - Masahito Yamazaki
- Integrated Bioscience Section, Graduate School of Science and Technology , Shizuoka University , Shizuoka 422-8529 , Japan
- Nanomaterials Research Division, Research Institute of Electronics , Shizuoka University , 836 Oya , Suruga-ku, Shizuoka 422-8529 , Japan
- Department of Physics, Faculty of Science , Shizuoka University , Shizuoka 422-8529 , Japan
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19
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Savini F, Bobone S, Roversi D, Mangoni ML, Stella L. From liposomes to cells: Filling the gap between physicochemical and microbiological studies of the activity and selectivity of host‐defense peptides. Pept Sci (Hoboken) 2018. [DOI: 10.1002/pep2.24041] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Filippo Savini
- Department of Chemical Science and TechnologiesUniversity of Rome Tor VergataRome00133 Italy
| | - Sara Bobone
- Department of Chemical Science and TechnologiesUniversity of Rome Tor VergataRome00133 Italy
| | - Daniela Roversi
- Department of Chemical Science and TechnologiesUniversity of Rome Tor VergataRome00133 Italy
| | - Maria Luisa Mangoni
- Department of Biochemical Sciences, Laboratory affiliated to Pasteur Italia‐Fondazione Cenci BolognettiSapienza University of RomeRome, via degli Apuli9‐00185 Italy
| | - Lorenzo Stella
- Department of Chemical Science and TechnologiesUniversity of Rome Tor VergataRome00133 Italy
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20
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Braun S, Pokorná Š, Šachl R, Hof M, Heerklotz H, Hoernke M. Biomembrane Permeabilization: Statistics of Individual Leakage Events Harmonize the Interpretation of Vesicle Leakage. ACS NANO 2018; 12:813-819. [PMID: 29244483 DOI: 10.1021/acsnano.7b08184] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The mode of action of membrane-active molecules, such as antimicrobial, anticancer, cell penetrating, and fusion peptides and their synthetic mimics, transfection agents, drug permeation enhancers, and biological signaling molecules (e.g., quorum sensing), involves either the general or local destabilization of the target membrane or the formation of defined, rather stable pores. Some effects aim at killing the cell, while others need to be limited in space and time to avoid serious damage. Biological tests reveal translocation of compounds and cell death but do not provide a detailed, mechanistic, and quantitative understanding of the modes of action and their molecular basis. Model membrane studies of membrane leakage have been used for decades to tackle this issue, but their interpretation in terms of biology has remained challenging and often quite limited. Here we compare two recent, powerful protocols to study model membrane leakage: the microscopic detection of dye influx into giant liposomes and time-correlated single photon counting experiments to characterize dye efflux from large unilamellar vesicles. A statistical treatment of both data sets does not only harmonize apparent discrepancies but also makes us aware of principal issues that have been confusing the interpretation of model membrane leakage data so far. Moreover, our study reveals a fundamental difference between nano- and microscale systems that needs to be taken into account when conclusions about microscale objects, such as cells, are drawn from nanoscale models.
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Affiliation(s)
- Stefan Braun
- Department of Pharmaceutical Technology and Biopharmacy, University of Freiburg , 79104 Freiburg im Breisgau, Germany
| | - Šárka Pokorná
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic , 182 23 Prague, Czech Republic
| | - Radek Šachl
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic , 182 23 Prague, Czech Republic
| | - Martin Hof
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic , 182 23 Prague, Czech Republic
| | - Heiko Heerklotz
- Department of Pharmaceutical Technology and Biopharmacy, University of Freiburg , 79104 Freiburg im Breisgau, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg , 79104 Freiburg im Breisgau, Germany
- Leslie Dan Faculty of Pharmacy, University of Toronto , 144 College St., Toronto, Ontario M5S 3M2, Canada
| | - Maria Hoernke
- Department of Pharmaceutical Technology and Biopharmacy, University of Freiburg , 79104 Freiburg im Breisgau, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg , 79104 Freiburg im Breisgau, Germany
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21
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Peña‐Blanco A, García‐Sáez AJ. Bax, Bak and beyond — mitochondrial performance in apoptosis. FEBS J 2017; 285:416-431. [DOI: 10.1111/febs.14186] [Citation(s) in RCA: 340] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/12/2017] [Accepted: 07/26/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Aida Peña‐Blanco
- Interfaculty Institute of Biochemistry Tübingen University Germany
| | - Ana J. García‐Sáez
- Interfaculty Institute of Biochemistry Tübingen University Germany
- Max‐Planck Institute for Intelligent Systems Stuttgart Germany
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22
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Dingeldein APG, Pokorná Š, Lidman M, Sparrman T, Šachl R, Hof M, Gröbner G. Apoptotic Bax at Oxidatively Stressed Mitochondrial Membranes: Lipid Dynamics and Permeabilization. Biophys J 2017; 112:2147-2158. [PMID: 28538152 DOI: 10.1016/j.bpj.2017.04.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 02/23/2017] [Accepted: 04/05/2017] [Indexed: 12/20/2022] Open
Abstract
Mitochondria are crucial compartments of eukaryotic cells because they function as the cellular power plant and play a central role in the early stages of programmed cell death (apoptosis). To avoid undesired cell death, this apoptotic pathway is tightly regulated by members of the Bcl-2 protein family, which interact on the external surface of the mitochondria, i.e., the mitochondrial outer membrane (MOM), and modulate its permeability to apoptotic factors, controlling their release into the cytosol. A growing body of evidence suggests that the MOM lipids play active roles in this permeabilization process. In particular, oxidized phospholipids (OxPls) formed under intracellular stress seem to directly induce apoptotic activity at the MOM. Here we show that the process of MOM pore formation is sensitive to the type of OxPls species that are generated. We created MOM-mimicking liposome systems, which resemble the cellular situation before apoptosis and upon triggering of oxidative stress conditions. These vesicles were studied using 31P solid-state magic-angle-spinning nuclear magnetic resonance spectroscopy and differential scanning calorimetry, together with dye leakage assays. Direct polarization and cross-polarization nuclear magnetic resonance experiments enabled us to probe the heterogeneity of these membranes and their associated molecular dynamics. The addition of apoptotic Bax protein to OxPls-containing vesicles drastically changed the membranes' dynamic behavior, almost completely negating the previously observed effect of temperature on the lipids' molecular dynamics and inducing an ordering effect that led to more cooperative membrane melting. Our results support the hypothesis that the mitochondrion-specific lipid cardiolipin functions as a first contact site for Bax during its translocation to the MOM in the onset of apoptosis. In addition, dye leakage assays revealed that different OxPls species in the MOM-mimicking vesicles can have opposing effects on Bax pore formation.
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Affiliation(s)
| | - Šárka Pokorná
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Lidman
- Department of Chemistry, Umeå University, Umeå, Sweden
| | | | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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23
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Faust JE, Yang PY, Huang HW. Action of Antimicrobial Peptides on Bacterial and Lipid Membranes: A Direct Comparison. Biophys J 2017; 112:1663-1672. [PMID: 28445757 PMCID: PMC5406281 DOI: 10.1016/j.bpj.2017.03.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 03/02/2017] [Accepted: 03/03/2017] [Indexed: 11/29/2022] Open
Abstract
The bacterial membrane represents an attractive target for the design of new antibiotics to combat widespread bacterial resistance. Understanding how antimicrobial peptides (AMPs) and other membrane-active agents attack membranes could facilitate the design of new, effective antimicrobials. Despite intense study of AMPs on model membranes, we do not know how well the mechanism of attack translates to real biological membranes. To that end, we have characterized the attack of AMPs on Escherichia coli cytoplasmic membranes and directly compared this action to model membranes. AMPs induce membrane permeability in E. coli spheroplasts or giant unilamellar vesicles (GUVs) under well-defined concentrations of AMPs and fluorescent molecules. The action of AMPs on spheroplasts is unique in producing an intracellular fluorescence intensity time curve that increases in a sigmoidal fashion to a steady state. This regular pattern is reproducible by melittin, LL37, and alamethicin but not by CCCP or daptomycin, agents known to cause ion leakage. Remarkably, a similar pattern was also reproduced in GUVs. Indeed the steady-state membrane permeability induced by AMPs is quantitatively the same in spheroplasts and GUVs. There are, however, interesting dissimilarities in details that reveal differences between bacterial and lipid membranes. Spheroplast membranes are permeabilized by a wide range of AMP concentrations to the same steady-state membrane permeability. In contrast, only a narrow range of AMP concentrations permeabilized GUVs to a steady state. Tension in GUVs also influences the action of AMPs, whereas the spheroplast membranes are tensionless. Despite these differences, our results provide a strong support for using model membranes to study the molecular interactions of AMPs with bacterial membranes. As far as we know, this is the first time the actions of AMPs, on bacterial membranes and on model membranes, have been directly and quantitatively compared.
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Affiliation(s)
- Joseph E Faust
- Department of Physics and Astronomy, Rice University, Houston, Texas
| | - Pei-Yin Yang
- Department of Physics and Astronomy, Rice University, Houston, Texas
| | - Huey W Huang
- Department of Physics and Astronomy, Rice University, Houston, Texas.
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24
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Cosentino K, García-Sáez AJ. Bax and Bak Pores: Are We Closing the Circle? Trends Cell Biol 2016; 27:266-275. [PMID: 27932064 DOI: 10.1016/j.tcb.2016.11.004] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/28/2016] [Accepted: 11/07/2016] [Indexed: 01/19/2023]
Abstract
Bax and its homolog Bak are key regulators of the mitochondrial pathway of apoptosis. On cell stress Bax and Bak accumulate at distinct foci on the mitochondrial surface where they undergo a conformational change, oligomerize, and mediate cytochrome c release, leading to cell death. The molecular mechanisms of Bax and Bak assembly and mitochondrial permeabilization have remained a longstanding question in the field. Recent structural and biophysical studies at several length scales have shed light on key aspects of Bax and Bak function that have shifted how we think this process occurs. These discoveries reveal an unexpected molecular mechanism in which Bax (and likely Bak) dimers assemble into oligomers with an even number of molecules that fully or partially delineate pores of different sizes to permeabilize the mitochondrial outer membrane (MOM) during apoptosis.
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Affiliation(s)
- Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany; Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, Stuttgart, Germany.
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25
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PE and PS Lipids Synergistically Enhance Membrane Poration by a Peptide with Anticancer Properties. Biophys J 2016; 109:936-47. [PMID: 26331251 PMCID: PMC4564682 DOI: 10.1016/j.bpj.2015.07.033] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 07/10/2015] [Accepted: 07/22/2015] [Indexed: 11/26/2022] Open
Abstract
Polybia-MP1 (MP1) is a bioactive host-defense peptide with known anticancer properties. Its activity is attributed to excess serine (phosphatidylserine (PS)) on the outer leaflet of cancer cells. Recently, higher quantities of phosphatidylethanolamine (PE) were also found at these cells’ surface. We investigate the interaction of MP1 with model membranes in the presence and absence of POPS (PS) and DOPE (PE) to understand the role of lipid composition in MP1’s anticancer characteristics. Indeed we find that PS lipids significantly enhance the bound concentration of peptide on the membrane by a factor of 7–8. However, through a combination of membrane permeability assays and imaging techniques we find that PE significantly increases the susceptibility of the membrane to disruption by these peptides and causes an order-of-magnitude increase in membrane permeability by facilitating the formation of larger transmembrane pores. Significantly, atomic-force microscopy imaging reveals differences in the pore formation mechanism with and without the presence of PE. Therefore, PS and PE lipids synergistically combine to enhance membrane poration by MP1, implying that the combined enrichment of both these lipids in the outer leaflet of cancer cells is highly significant for MP1’s anticancer action. These mechanistic insights could aid development of novel chemotherapeutics that target pathological changes in the lipid composition of cancerous cells.
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26
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Amaro M, Šachl R, Jurkiewicz P, Coutinho A, Prieto M, Hof M. Time-resolved fluorescence in lipid bilayers: selected applications and advantages over steady state. Biophys J 2016; 107:2751-2760. [PMID: 25517142 DOI: 10.1016/j.bpj.2014.10.058] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/23/2014] [Accepted: 10/29/2014] [Indexed: 01/23/2023] Open
Abstract
Fluorescence methods are versatile tools for obtaining dynamic and topological information about biomembranes because the molecular interactions taking place in lipid membranes frequently occur on the same timescale as fluorescence emission. The fluorescence intensity decay, in particular, is a powerful reporter of the molecular environment of a fluorophore. The fluorescence lifetime can be sensitive to the local polarity, hydration, viscosity, and/or presence of fluorescence quenchers/energy acceptors within several nanometers of the vicinity of a fluorophore. Illustrative examples of how time-resolved fluorescence measurements can provide more valuable and detailed information about a system than the time-integrated (steady-state) approach will be presented in this review: 1), determination of membrane polarity and mobility using time-dependent spectral shifts; 2), identification of submicroscopic domains by fluorescence lifetime imaging microscopy; 3), elucidation of membrane leakage mechanisms from dye self-quenching assays; and 4), evaluation of nanodomain sizes by time-resolved Förster resonance energy transfer measurements.
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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., Prague, Czech Republic
| | - Radek Šachl
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic
| | - Piotr Jurkiewicz
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic
| | - Ana Coutinho
- Centre for Molecular Chemistry and Physics and Instituto de Nanociência e Nanotecnologia, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; Departamento Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Manuel Prieto
- Centre for Molecular Chemistry and Physics and Instituto de Nanociência e Nanotecnologia, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, 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., Prague, Czech Republic.
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27
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Lira RB, Steinkühler J, Knorr RL, Dimova R, Riske KA. Posing for a picture: vesicle immobilization in agarose gel. Sci Rep 2016; 6:25254. [PMID: 27140695 PMCID: PMC4853705 DOI: 10.1038/srep25254] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/13/2016] [Indexed: 01/14/2023] Open
Abstract
Taking a photo typically requires the object of interest to stand still. In science, imaging is potentiated by optical and electron microscopy. However, living and soft matter are not still. Thus, biological preparations for microscopy usually include a fixation step. Similarly, immobilization strategies are required for or substantially facilitate imaging of cells or lipid vesicles, and even more so for acquiring high-quality data via fluorescence-based techniques. Here, we describe a simple yet efficient method to immobilize objects such as lipid vesicles with sizes between 0.1 and 100 μm using agarose gel. We show that while large and giant unilamellar vesicles (LUVs and GUVs) can be caged in the pockets of the gel meshwork, small molecules, proteins and micelles remain free to diffuse through the gel and interact with membranes as in agarose-free solutions, and complex biochemical reactions involving several proteins can proceed in the gel. At the same time, immobilization in agarose has no adverse effect on the GUV size and stability. By applying techniques such as FRAP and FCS, we show that the lateral diffusion of lipids is not affected by the gel. Finally, our immobilization strategy allows capturing high-resolution 3D images of GUVs.
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Affiliation(s)
- Rafael B. Lira
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Jan Steinkühler
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Roland L. Knorr
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Rumiana Dimova
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Karin A. Riske
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil
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28
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Lidman M, Pokorná Š, Dingeldein APG, Sparrman T, Wallgren M, Šachl R, Hof M, Gröbner G. The oxidized phospholipid PazePC promotes permeabilization of mitochondrial membranes by Bax. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1288-97. [PMID: 26947183 DOI: 10.1016/j.bbamem.2016.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 02/24/2016] [Accepted: 03/02/2016] [Indexed: 12/25/2022]
Abstract
Mitochondria play a crucial role in programmed cell death via the intrinsic apoptotic pathway, which is tightly regulated by the B-cell CLL/lymphoma-2 (Bcl-2) protein family. Intracellular oxidative stress causes the translocation of Bax, a pro-apoptotic family member, to the mitochondrial outer membrane (MOM) where it induces membrane permeabilization. Oxidized phospholipids (OxPls) generated in the MOM during oxidative stress directly affect the onset and progression of mitochondria-mediated apoptosis. Here we use MOM-mimicking lipid vesicles doped with varying concentrations of 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC), an OxPl species known to significantly enhance Bax-membrane association, to investigate three key aspects of Bax's action at the MOM: 1) induction of Bax pores in membranes without additional mediator proteins, 2) existence of a threshold OxPl concentration required for Bax-membrane action and 3) mechanism by which PazePC disturbs membrane organization to facilitate Bax penetration. Fluorescence leakage studies revealed that Bax-induced leakage, especially its rate, increased with the vesicles' PazePC content without any detectable threshold neither for OxPl nor Bax. Moreover, the leakage rate correlated with the Bax to lipid ratio and the PazePC content. Solid state NMR studies and calorimetric experiments on the lipid vesicles confirmed that OxPl incorporation disrupted the membrane's organization, enabling Bax to penetrate into the membrane. In addition, 15N cross polarization (CP) and insensitive nuclei enhanced by polarization transfer (INEPT) MAS NMR experiments using uniformly (15)N-labeled Bax revealed dynamically restricted helical segments of Bax embedded in the membrane, while highly flexible protein segments were located outside or at the membrane surface.
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Affiliation(s)
- Martin Lidman
- Department of Chemistry, University of Umeå, SE-901 87 Umeå, Sweden
| | - Šárka Pokorná
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 182 23 Prague 8, Czech Republic; Department of Biochemistry, Charles University, Hlavova 8, 128 40 Prague 2, Czech Republic
| | | | - Tobias Sparrman
- Department of Chemistry, University of Umeå, SE-901 87 Umeå, Sweden
| | - Marcus Wallgren
- Department of Medical Chemistry and Biophysics, University of Umeå, SE-901 87 Umeå, Sweden
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 182 23 Prague 8, Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 182 23 Prague 8, Czech Republic
| | - Gerhard Gröbner
- Department of Chemistry, University of Umeå, SE-901 87 Umeå, Sweden.
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29
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Salvador-Gallego R, Mund M, Cosentino K, Schneider J, Unsay J, Schraermeyer U, Engelhardt J, Ries J, García-Sáez AJ. Bax assembly into rings and arcs in apoptotic mitochondria is linked to membrane pores. EMBO J 2016; 35:389-401. [PMID: 26783362 DOI: 10.15252/embj.201593384] [Citation(s) in RCA: 215] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/01/2015] [Indexed: 11/09/2022] Open
Abstract
Bax is a key regulator of apoptosis that, under cell stress, accumulates at mitochondria, where it oligomerizes to mediate the permeabilization of the mitochondrial outer membrane leading to cytochrome c release and cell death. However, the underlying mechanism behind Bax function remains poorly understood. Here, we studied the spatial organization of Bax in apoptotic cells using dual-color single-molecule localization-based super-resolution microscopy. We show that active Bax clustered into a broad distribution of distinct architectures, including full rings, as well as linear and arc-shaped oligomeric assemblies that localized in discrete foci along mitochondria. Remarkably, both rings and arcs assemblies of Bax perforated the membrane, as revealed by atomic force microscopy in lipid bilayers. Our data identify the supramolecular organization of Bax during apoptosis and support a molecular mechanism in which Bax fully or partially delineates pores of different sizes to permeabilize the mitochondrial outer membrane.
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Affiliation(s)
- Raquel Salvador-Gallego
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Markus Mund
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Katia Cosentino
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | | | - Joseph Unsay
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Ulrich Schraermeyer
- Core Facility for Electron Microscopy Section for Experimental Vitreoretinal Surgery, Universitätsklinikum Tübingen, Tübingen, Germany
| | | | - Jonas Ries
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany Max Planck Institute for Intelligent Systems, Stuttgart, Germany
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30
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Moniruzzaman M, Alam JM, Dohra H, Yamazaki M. Antimicrobial Peptide Lactoferricin B-Induced Rapid Leakage of Internal Contents from Single Giant Unilamellar Vesicles. Biochemistry 2015; 54:5802-14. [DOI: 10.1021/acs.biochem.5b00594] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Md. Moniruzzaman
- Integrated Bioscience Section, Graduate School of
Science and Technology, ‡Nanomaterials Research
Division, Research Institute of Electronics, §Instrumental Research Support Office,
Research Institute of Green Science and Technology, and ∥Department of Physics, Faculty of
Science, Shizuoka University, Shizuoka 422-8529, Japan
| | - Jahangir Md. Alam
- Integrated Bioscience Section, Graduate School of
Science and Technology, ‡Nanomaterials Research
Division, Research Institute of Electronics, §Instrumental Research Support Office,
Research Institute of Green Science and Technology, and ∥Department of Physics, Faculty of
Science, Shizuoka University, Shizuoka 422-8529, Japan
| | - Hideo Dohra
- Integrated Bioscience Section, Graduate School of
Science and Technology, ‡Nanomaterials Research
Division, Research Institute of Electronics, §Instrumental Research Support Office,
Research Institute of Green Science and Technology, and ∥Department of Physics, Faculty of
Science, Shizuoka University, Shizuoka 422-8529, Japan
| | - Masahito Yamazaki
- Integrated Bioscience Section, Graduate School of
Science and Technology, ‡Nanomaterials Research
Division, Research Institute of Electronics, §Instrumental Research Support Office,
Research Institute of Green Science and Technology, and ∥Department of Physics, Faculty of
Science, Shizuoka University, Shizuoka 422-8529, Japan
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31
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Hovakeemian SG, Liu R, Gellman SH, Heerklotz H. Correlating antimicrobial activity and model membrane leakage induced by nylon-3 polymers and detergents. SOFT MATTER 2015; 11:6840-51. [PMID: 26234884 PMCID: PMC4666704 DOI: 10.1039/c5sm01521a] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Most antimicrobial peptides act upon target microorganisms by permeabilizing their membranes. The mode of action is often assessed by vesicle leakage experiments that use model membranes, with the assumption that biological activity correlates with the permeabilization of the lipid bilayer. The current work aims to extend the interpretation of vesicle leakage results and examine the correlation between vesicle leakage and antimicrobial activity. To this end, we used a lifetime-based leakage assay with calcein-loaded vesicles to study the membrane permeabilizing properties of a novel antifungal polymer poly-NM, two of its analogs, and a series of detergents. In conjunction, the biological activities of these compounds against Candida albicans were assessed and correlated with data from vesicle leakage. Poly-NM induces all-or-none leakage in polar yeast lipid vesicles at the polymer's MIC, 3 μg mL(-1). At this and higher concentrations, complete leakage after an initial lag time was observed. Concerted activity tests imply that this polymer acts independently of the detergent octyl glucoside (OG) for both vesicle leakage and activity against C. albicans spheroplasts. In addition, poly-NM was found to have negligible activity against zwitterionic vesicles and red blood cells. Our results provide a consistent, detailed picture of the mode of action of poly-NM: this polymer induces membrane leakage by electrostatic lipid clustering. In contrast, poly-MM:CO, a nylon-3 polymer comprised of both cationic and hydrophobic segments, seems to act by a different mechanism that involves membrane asymmetry stress. Vesicle leakage for this polymer is transient (limited to <100%) and graded, non-specific among zwitterionic and polar yeast lipid vesicles, additive with detergent action, and correlates poorly with biological activity. Based on these results, we conclude that comprehensive leakage experiments can provide a detailed description of the mode of action of membrane permeabilizing compounds. Without this thorough approach, it would have been logical to assume that the two nylon-3 polymers we examined act via similar mechanisms; it is surprising that their mechanisms are so distinct. Some, but not all mechanisms of vesicle permeabilization allow for antimicrobial activity.
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32
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Correia C, Lee SH, Meng XW, Vincelette ND, Knorr KLB, Ding H, Nowakowski GS, Dai H, Kaufmann SH. Emerging understanding of Bcl-2 biology: Implications for neoplastic progression and treatment. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1658-71. [PMID: 25827952 DOI: 10.1016/j.bbamcr.2015.03.012] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/20/2015] [Accepted: 03/22/2015] [Indexed: 02/07/2023]
Abstract
Bcl-2, the founding member of a family of apoptotic regulators, was initially identified as the protein product of a gene that is translocated and overexpressed in greater than 85% of follicular lymphomas (FLs). Thirty years later we now understand that anti-apoptotic Bcl-2 family members modulate the intrinsic apoptotic pathway by binding and neutralizing the mitochondrial permeabilizers Bax and Bak as well as a variety of pro-apoptotic proteins, including the cellular stress sensors Bim, Bid, Puma, Bad, Bmf and Noxa. Despite extensive investigation of all of these proteins, important questions remain. For example, how Bax and Bak breach the outer mitochondrial membrane remains poorly understood. Likewise, how the functions of anti-apoptotic Bcl-2 family members such as eponymous Bcl-2 are affected by phosphorylation or cancer-associated mutations has been incompletely defined. Finally, whether Bcl-2 family members can be successfully targeted for therapeutic advantage is only now being investigated in the clinic. Here we review recent advances in understanding Bcl-2 family biology and biochemistry that begin to address these questions.
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Affiliation(s)
- Cristina Correia
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, MN 55905, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA
| | - Sun-Hee Lee
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, MN 55905, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA
| | - X Wei Meng
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, MN 55905, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA
| | - Nicole D Vincelette
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA
| | - Katherine L B Knorr
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA
| | - Husheng Ding
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, MN 55905, USA
| | - Grzegorz S Nowakowski
- Division of Hematology, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Haiming Dai
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, MN 55905, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA.
| | - Scott H Kaufmann
- Division of Oncology Research, Department of Oncology, Mayo Clinic, Rochester, MN 55905, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA; Division of Hematology, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
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33
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Giménez D, Sánchez-Muñoz OL, Salgado J. Direct observation of nanometer-scale pores of melittin in supported lipid monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3146-58. [PMID: 25705986 DOI: 10.1021/la504293q] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Melittin is the most studied membrane-active peptide and archetype within a large and diverse group of pore formers. However, the molecular characteristics of melittin pores remain largely unknown. Herein, we show by atomic force microscopy (AFM) that lipid monolayers in the presence of melittin are decorated with numerous regularly shaped circular pores that can be distinguished from nonspecific monolayer defects. The specificity of these pores is reinforced through a statistical evaluation of depressions found in Langmuir-Blodgett monolayers in the presence and absence of melittin, which eventually allows characterization of the melittin-induced pores at a quantitative low-resolution level. We observed that the large majority of pores exhibit near-circular symmetry and a Gaussian distribution in size, with a mean diameter of ∼8.7 nm. A distinctive feature is a ring of material found around the pores, made by, on average, three positive peaks, with a height over the level of the lipidic background of ∼0.23 nm. This protruding rim is most likely due to the presence of melittin near the pore border. Although the current resolution of the AFM images in the {x, y} plane does not allow distinction of the specific organization of the peptide molecules, these results provide an unprecedented view of melittin pores formed in lipidic interfaces and open new perspectives for future structural investigations of these and other pore-forming peptides and proteins using supported monolayers.
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Affiliation(s)
- Diana Giménez
- Institute of Molecular Science (ICMol), University of Valencia. C/Catedrático José Beltrán, 2, 46980 Paterna, Valencia, Spain
| | - Orlando L Sánchez-Muñoz
- Institute of Molecular Science (ICMol), University of Valencia. C/Catedrático José Beltrán, 2, 46980 Paterna, Valencia, Spain
| | - Jesús Salgado
- Institute of Molecular Science (ICMol), University of Valencia. C/Catedrático José Beltrán, 2, 46980 Paterna, Valencia, Spain
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34
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Kristensen K, Ehrlich N, Henriksen JR, Andresen TL. Single-vesicle detection and analysis of peptide-induced membrane permeabilization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2472-2483. [PMID: 25664684 DOI: 10.1021/la504752u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The capability of membrane-active peptides to disrupt phospholipid membranes is often studied by investigating peptide-induced leakage of quenched fluorescent molecules from large unilamellar lipid vesicles. In this article, we explore two fluorescence microscopy-based single-vesicle detection methods as alternatives to the quenching-based assays for studying peptide-induced leakage from large unilamellar lipid vesicles. Specifically, we use fluorescence correlation spectroscopy (FCS) to study the leakage of fluorescent molecules of different sizes from large unilamellar lipid vesicles dispersed in aqueous solution, and we use confocal imaging of surface-immobilized large unilamellar lipid vesicles to investigate whether there are heterogeneities in leakage between individual vesicles. Of importance, we design an experimental protocol that allows us to quantitatively correlate the results of the two methods; accordingly, it can be assumed that the two methods provide complementary information about the same leakage process. We use the two methods to investigate the membrane-permeabilizing activities of three well-studied cationic membrane-active peptides: mastoparan X, melittin, and magainin 2. The FCS results show that leakage induced by magainin 2 is less dependent on the size of the encapsulated fluorescent molecules than leakage induced by mastoparan X and melittin. The confocal imaging results show that all three peptides induce leakage by a heterogeneous process in which one portion of the vesicles are completely emptied of their contents but another portion of the vesicles are only partially emptied. These pieces of information regarding leakage induced by mastoparan X, melittin, and magainin 2 could not readily have been obtained by the established assays for studying peptide-induced leakage from lipid vesicles.
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Affiliation(s)
- Kasper Kristensen
- Department of Micro- and Nanotechnology, DTU Nanotech, Technical University of Denmark , 2800 Kongens Lyngby, Denmark
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35
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Sun D, Forsman J, Woodward CE. Amphipathic membrane-active peptides recognize and stabilize ruptured membrane pores: exploring cause and effect with coarse-grained simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:752-761. [PMID: 25490714 DOI: 10.1021/la5038266] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Induction of membrane pores has been suggested as the common molecular action by which a variety of amphipathic membrane-active peptides cause damage to cells. In this study, we have performed coarse-grained molecular dynamics simulations to establish two clear molecular processes that seem critical for the activity of amphipathic peptides. They are (i) the recognition and (ii) the stabilization of ruptured membrane pores. By considering 12 structurally different peptide types, we reveal that peptide secondary structure content, hydrophobicity, and length are important physicochemical factors that allow amphipathic peptides to aggregate in and stabilize ruptured membrane pores. The simulated inner diameters of peptide-stabilized membrane pores are in good agreement with available experimental data. However, the orientations of α-helical peptides in the membrane pore were found to be quite dispersed. This supports recent challenges to the traditional depictions to peptide orientations in the classical toroidal and barrel-stave pore models.
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Affiliation(s)
- Delin Sun
- School of Physical, Environmental and Mathematical Sciences, University of New South Wales , Canberra ACT 2600, Australia
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36
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Beales PA, Ciani B, Cleasby AJ. Nature's lessons in design: nanomachines to scaffold, remodel and shape membrane compartments. Phys Chem Chem Phys 2015; 17:15489-507. [DOI: 10.1039/c5cp00480b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Our understanding of the membrane sculpting capabilities of proteins from experimental model systems could be used to construct functional compartmentalised architectures for the engineering of synthetic cells.
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Affiliation(s)
- Paul A. Beales
- School of Chemistry and Astbury Centre for Structural Molecular Biology
- University of Leeds
- Leeds LS2 9JT
- UK
| | - Barbara Ciani
- Centre for Membrane Interaction and Dynamics
- Department of Chemistry
- University of Sheffield
- Sheffield S3 7HF
- UK
| | - Alexa J. Cleasby
- Centre for Membrane Interaction and Dynamics
- Department of Chemistry
- University of Sheffield
- Sheffield S3 7HF
- UK
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37
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Patel H, Huynh Q, Bärlehner D, Heerklotz H. Additive and synergistic membrane permeabilization by antimicrobial (lipo)peptides and detergents. Biophys J 2014; 106:2115-25. [PMID: 24853740 DOI: 10.1016/j.bpj.2014.04.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 03/10/2014] [Accepted: 04/01/2014] [Indexed: 12/27/2022] Open
Abstract
Certain antibiotic peptides are thought to permeabilize membranes of pathogens by effects that are also observed for simple detergents, such as membrane thinning and disordering, asymmetric bilayer expansion, toroidal pore formation, and micellization. Here we test the hypothesis that such peptides act additively with detergents when applied in parallel. Additivity is defined analogously to a fractional inhibitory concentration index of unity, and the extent and mechanism of leakage is measured by the fluorescence lifetime-based vesicle leakage assay using calcein-loaded vesicles. Good additivity was found for the concerted action of magainin 2, the fungicidal lipopeptide class of surfactins from Bacillus subtilis QST713, and the detergent octyl glucoside, respectively, with the detergent C12EO8. Synergistic or superadditive action was observed for fengycins from B. subtilis, as well as the detergent CHAPS, when combined with C12EO8. The results illustrate two mechanisms of synergistic action: First, maximal leakage requires an optimum degree of heterogeneity in the system that may be achieved by mixing a graded with an all-or-none permeabilizer. (The optimal perturbation should be focused to certain defect structures, yet not to the extent that some vesicles are not affected at all.) Second, a cosurfactant may enhance the bioavailability of a poorly soluble peptide. The results are important for understanding the concerted action of membrane-permeabilizing compounds in biology as well as for optimizing formulations of such antimicrobials for medical applications or crop protection.
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Affiliation(s)
- Hiren Patel
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada; Department of Biophysics and Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Quang Huynh
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Dominik Bärlehner
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Heiko Heerklotz
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada; Institut für Medizinische Physik und Biophysik, Universität Leipzig, Leipzig, Germany.
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38
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Gilbert RJ, Serra MD, Froelich CJ, Wallace MI, Anderluh G. Membrane pore formation at protein–lipid interfaces. Trends Biochem Sci 2014; 39:510-6. [DOI: 10.1016/j.tibs.2014.09.002] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/13/2014] [Accepted: 09/15/2014] [Indexed: 11/15/2022]
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39
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Apoptotic pore formation is associated with in-plane insertion of Bak or Bax central helices into the mitochondrial outer membrane. Proc Natl Acad Sci U S A 2014; 111:E4076-85. [PMID: 25228770 DOI: 10.1073/pnas.1415142111] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The pivotal step on the mitochondrial pathway to apoptosis is permeabilization of the mitochondrial outer membrane (MOM) by oligomers of the B-cell lymphoma-2 (Bcl-2) family members Bak or Bax. However, how they disrupt MOM integrity is unknown. A longstanding model is that activated Bak and Bax insert two α-helices, α5 and α6, as a hairpin across the MOM, but recent insights on the oligomer structures question this model. We have clarified how these helices contribute to MOM perforation by determining that, in the oligomers, Bak α5 (like Bax α5) remains part of the protein core and that a membrane-impermeable cysteine reagent can label cysteines placed at many positions in α5 and α6 of both Bak and Bax. The results are inconsistent with the hairpin insertion model but support an in-plane model in which α5 and α6 collapse onto the membrane and insert shallowly to drive formation of proteolipidic pores.
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40
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Abstract
Pneumolysin is a member of the cholesterol-dependent cytolysin (CDC) family of pore-forming proteins that are produced as water-soluble monomers or dimers, bind to target membranes and oligomerize into large ring-shaped assemblies comprising approximately 40 subunits and approximately 30 nm across. This pre-pore assembly then refolds to punch a large hole in the lipid bilayer. However, in addition to forming large pores, pneumolysin and other CDCs form smaller lesions characterized by low electrical conductance. Owing to the observation of arc-like (rather than full-ring) oligomers by electron microscopy, it has been hypothesized that smaller oligomers explain smaller functional pores. To investigate whether this is the case, we performed cryo-electron tomography of pneumolysin oligomers on model lipid membranes. We then used sub-tomogram classification and averaging to determine representative membrane-bound low-resolution structures and identified pre-pores versus pores by the presence of membrane within the oligomeric curve. We found pre-pore and pore forms of both complete (ring) and incomplete (arc) oligomers and conclude that arc-shaped oligomeric assemblies of pneumolysin can form pores. As the CDCs are evolutionarily related to the membrane attack complex/perforin family of proteins, which also form variably sized pores, our findings are of relevance to that class of proteins as well.
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Affiliation(s)
- Andreas F-P Sonnen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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41
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Cosentino K, García-Sáez AJ. Mitochondrial alterations in apoptosis. Chem Phys Lipids 2014; 181:62-75. [PMID: 24732580 DOI: 10.1016/j.chemphyslip.2014.04.001] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/20/2014] [Accepted: 04/02/2014] [Indexed: 12/31/2022]
Abstract
Besides their conventional role as energy suppliers for the cell, mitochondria in vertebrates are active regulators of apoptosis. They release apoptotic factors from the intermembrane space into the cytosol through a mechanism that involves the Bcl-2 protein family, mediating permeabilization of the outer mitochondrial membrane. Associated with this event, a number of additional changes affect mitochondria during apoptosis. They include loss of important mitochondrial functions, such as the ability to maintain calcium homeostasis and to generate ATP, as well as mitochondrial fragmentation and cristae remodeling. Moreover, the lipidic component of mitochondrial membranes undergoes important alterations in composition and distribution, which have turned out to be relevant regulatory events for the proteins involved in apoptotic mitochondrial damage.
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Affiliation(s)
- Katia Cosentino
- German Cancer Research Center, Heidelberg, Germany; Max-Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Ana J García-Sáez
- German Cancer Research Center, Heidelberg, Germany; Max-Planck Institute for Intelligent Systems, Stuttgart, Germany; Interfaculty Institute of Biochemistry (IFIB), University of Tübingen, Tübingen, Germany.
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42
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Wiedman G, Fuselier T, He J, Searson PC, Hristova K, Wimley WC. Highly efficient macromolecule-sized poration of lipid bilayers by a synthetically evolved peptide. J Am Chem Soc 2014; 136:4724-31. [PMID: 24588399 PMCID: PMC3985440 DOI: 10.1021/ja500462s] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Indexed: 12/30/2022]
Abstract
Peptides that self-assemble, at low concentration, into bilayer-spanning pores which allow the passage of macromolecules would be beneficial in multiple areas of biotechnology. However, there are few, if any, natural or designed peptides that have this property. Here we show that the 26-residue peptide "MelP5", a synthetically evolved gain-of-function variant of the bee venom lytic peptide melittin identified in a high-throughput screen for small molecule leakage, enables the passage of macromolecules across bilayers under conditions where melittin and other pore-forming peptides do not. In surface-supported bilayers, MelP5 forms unusually high conductance, equilibrium pores at peptide:lipid ratios as low as 1:25000. The increase in bilayer conductance due to MelP5 is dramatically higher, per peptide, than the increase due to the parent sequence of melittin or other peptide pore formers. Here we also develop two novel assays for macromolecule leakage from vesicles, and we use them to characterize MelP5 pores in bilayers. We show that MelP5 allows the passage of macromolecules across vesicle membranes at peptide:lipid ratios as low as 1:500, and under conditions where neither osmotic lysis nor gross vesicle destabilization occur. The macromolecule-sized, equilibrium pores formed by MelP5 are unique as neither melittin nor other pore-forming peptides release macromolecules significantly under the same conditions. MelP5 thus appears to belong to a novel functional class of peptide that could form the foundation of multiple potential biotechnological applications.
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Affiliation(s)
- Gregory Wiedman
- Department
of Materials Science and Engineering, Johns
Hopkins University, Baltimore, Maryland 21218, United States
- Institute
for Nanobiotechnology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Taylor Fuselier
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Jing He
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Peter C. Searson
- Department
of Materials Science and Engineering, Johns
Hopkins University, Baltimore, Maryland 21218, United States
- Institute
for Nanobiotechnology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kalina Hristova
- Department
of Materials Science and Engineering, Johns
Hopkins University, Baltimore, Maryland 21218, United States
- Institute
for Nanobiotechnology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - William C. Wimley
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
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43
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Hermann E, Bleicken S, Subburaj Y, García-Sáez AJ. Automated analysis of giant unilamellar vesicles using circular Hough transformation. ACTA ACUST UNITED AC 2014; 30:1747-54. [PMID: 24554630 DOI: 10.1093/bioinformatics/btu102] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
MOTIVATION In order to obtain statistically relevant results, the study of membrane effects at the single-vesicle level requires the analysis of several hundreds of giant unilamellar vesicles (GUVs), which becomes a very time-consuming task if carried out manually. Complete and user-friendly software for fast and bias-free automated analysis has not been reported yet. RESULTS We developed a framework for the automated detection, tracking and analysis of individual GUVs on digital microscopy images. Our tool is suited to quantify protein binding to membranes as well as several aspects of membrane permeabilization on single vesicles. We demonstrate the applicability of the approach by comparing alternative activation methods for Bax, a pore-forming protein involved in mitochondrial permeabilization during apoptosis. AVAILABILITY AND IMPLEMENTATION The complete software is implemented in MATLAB (The MathWorks, Inc., USA) and available as a standalone as well as the full source code at http://www.ifib.uni-tuebingen.de/research/garcia-saez/guv-software.html.
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Affiliation(s)
- Eduard Hermann
- Max-Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart and Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Straße 4, 72076 Tübingen, Germany
| | - Stephanie Bleicken
- Max-Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart and Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Straße 4, 72076 Tübingen, Germany
| | - Yamunadevi Subburaj
- Max-Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart and Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Straße 4, 72076 Tübingen, Germany
| | - Ana J García-Sáez
- Max-Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart and Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Straße 4, 72076 Tübingen, Germany
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44
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Wheaten SA, Lakshmanan A, Almeida PF. Statistical analysis of peptide-induced graded and all-or-none fluxes in giant vesicles. Biophys J 2014; 105:432-43. [PMID: 23870264 DOI: 10.1016/j.bpj.2013.05.055] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 05/27/2013] [Accepted: 05/31/2013] [Indexed: 10/26/2022] Open
Abstract
Antimicrobial, cytolytic, and cell-penetrating peptides induce pores or perturbations in phospholipid membranes that result in fluxes of dyes into or out of lipid vesicles. Here we examine the fluxes induced by four of these membrane-active peptides in giant unilamellar vesicles. The type of flux is determined from the modality of the distributions of vesicles as a function of their dye content using the statistical Hartigan dip test. Graded and all-or-none fluxes correspond to unimodal and bimodal distributions, respectively. To understand how these distributions arise, we perform Monte Carlo simulations of peptide-induced dye flux into vesicles using a very simple model. The modality of the distributions depends on the rate constants of pore opening and closing, and dye flux. If the rate constants of pore opening and closing are both much smaller than that of dye flux through the pore, all-or-none influx occurs. However, if one of them, especially the rate constant for pore opening, increases significantly relative to the flux rate constant, the process becomes graded. In the experiments, we find that the flux type is the same in giant and large vesicles, for all peptides except one. But this one exception indicates that the flux type cannot be used to unambiguously predict the mechanism of membrane permeabilization by the peptides.
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Affiliation(s)
- Sterling A Wheaten
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina, USA
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45
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Islam MZ, Ariyama H, Alam JM, Yamazaki M. Entry of Cell-Penetrating Peptide Transportan 10 into a Single Vesicle by Translocating Across Lipid Membrane and Its Induced Pores. Biochemistry 2014; 53:386-96. [DOI: 10.1021/bi401406p] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Md. Zahidul Islam
- Integrated
Bioscience Section, Graduate School of Science and Technology, ‡Nanomaterials Research
Division, Research Institute of Electronics, and §Department of Physics, Graduate School
of Science, Shizuoka University, Shizuoka 422-8529, Japan
| | - Hirotaka Ariyama
- Integrated
Bioscience Section, Graduate School of Science and Technology, ‡Nanomaterials Research
Division, Research Institute of Electronics, and §Department of Physics, Graduate School
of Science, Shizuoka University, Shizuoka 422-8529, Japan
| | - Jahangir Md. Alam
- Integrated
Bioscience Section, Graduate School of Science and Technology, ‡Nanomaterials Research
Division, Research Institute of Electronics, and §Department of Physics, Graduate School
of Science, Shizuoka University, Shizuoka 422-8529, Japan
| | - Masahito Yamazaki
- Integrated
Bioscience Section, Graduate School of Science and Technology, ‡Nanomaterials Research
Division, Research Institute of Electronics, and §Department of Physics, Graduate School
of Science, Shizuoka University, Shizuoka 422-8529, Japan
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46
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Bleicken S, García-Sáez AJ. New biophysical methods to study the membrane activity of Bcl-2 proteins. Methods Mol Biol 2014; 1176:191-207. [PMID: 25030929 DOI: 10.1007/978-1-4939-0992-6_16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The proteins of Bcl-2 family are key regulators of apoptosis. Many Bcl-2 proteins have the unique ability to switch between two possible conformations, soluble in the cytosol or associated to cellular membranes. Importantly, their membrane-inserted form is the main responsible for their apoptotic function. Unfortunately, there are only a limited number of methods available to study the membrane activity of these proteins. Here, we present a methodology to study protein binding to membranes and membrane permeabilization at the single vesicle level. It is based on purified proteins and giant unilamellar vesicles and involves directly visualization of the process with a confocal microscope. This approach allows for the characterization of the membrane activity of the Bcl-2 proteins (or of any other pore-forming molecule) with unprecedented detail.
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Affiliation(s)
- Stephanie Bleicken
- Membrane Biophysics, Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569, Stuttgart, Germany
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47
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Islam MZ, Alam JM, Tamba Y, Karal MAS, Yamazaki M. The single GUV method for revealing the functions of antimicrobial, pore-forming toxin, and cell-penetrating peptides or proteins. Phys Chem Chem Phys 2014; 16:15752-67. [DOI: 10.1039/c4cp00717d] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The single GUV method provides detailed information on the elementary processes of peptide/protein-induced pore formation in lipid membranes and the entry of peptides into a GUV; specifically, the GUV method provides the rate constants of these processes.
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Affiliation(s)
- Md. Zahidul Islam
- Integrated Bioscience Section
- Graduate School of Science and Technology
- Shizuoka University
- Shizuoka, Japan
| | - Jahangir Md. Alam
- Nanomaterials Research Division
- Research Institute of Electronics
- Shizuoka University
- Shizuoka, Japan
| | | | - Mohammad Abu Sayem Karal
- Integrated Bioscience Section
- Graduate School of Science and Technology
- Shizuoka University
- Shizuoka, Japan
| | - Masahito Yamazaki
- Integrated Bioscience Section
- Graduate School of Science and Technology
- Shizuoka University
- Shizuoka, Japan
- Nanomaterials Research Division
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48
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Han E, Lee H. Effect of the structural difference between Bax-α5 and Bcl-xL-α5 on their interactions with lipid bilayers. Phys Chem Chem Phys 2014; 16:981-8. [DOI: 10.1039/c3cp53486c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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49
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The rheostat in the membrane: BCL-2 family proteins and apoptosis. Cell Death Differ 2013; 21:206-15. [PMID: 24162659 DOI: 10.1038/cdd.2013.153] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 08/22/2013] [Accepted: 09/17/2013] [Indexed: 12/19/2022] Open
Abstract
Apoptosis, a mechanism for programmed cell death, has key roles in human health and disease. Many signals for cellular life and death are regulated by the BCL-2 family proteins and converge at mitochondria, where cell fate is ultimately decided. The BCL-2 family includes both pro-life (e.g. BCL-XL) and pro-death (e.g. BAX, BAK) proteins. Previously, it was thought that a balance between these opposing proteins, like a simple 'rheostat', could control the sensitivity of cells to apoptotic stresses. Later, this rheostat concept had to be extended, when it became clear that BCL-2 family proteins regulate each other through a complex network of bimolecular interactions, some transient and some relatively stable. Now, studies have shown that the apoptotic circuitry is even more sophisticated, in that BCL-2 family interactions are spatially dynamic, even in nonapoptotic cells. For example, BAX and BCL-XL can shuttle between the cytoplasm and the mitochondrial outer membrane (MOM). Upstream signaling pathways can regulate the cytoplasmic-MOM equilibrium of BAX and thereby adjust the sensitivity of cells to apoptotic stimuli. Thus, we can view the MOM as the central locale of a dynamic life-death rheostat. BAX invariably forms extensive homo-oligomers after activation in membranes. However, recent studies, showing that activated BAX monomers determine the kinetics of MOM permeabilization (MOMP), perturb the lipid bilayer and form nanometer size pores, pose questions about the role of the oligomerization. Other lingering questions concern the molecular mechanisms of BAX redistribution between MOM and cytoplasm and the details of BAX/BAK-membrane assemblies. Future studies need to delineate how BCL-2 family proteins regulate MOMP, in concert with auxiliary MOM proteins, in a dynamic membrane environment. Technologies aimed at elucidating the structure and function of the full-length proteins in membranes are needed to illuminate some of these critical issues.
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50
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Bleicken S, Landeta O, Landajuela A, Basañez G, García-Sáez AJ. Proapoptotic Bax and Bak proteins form stable protein-permeable pores of tunable size. J Biol Chem 2013; 288:33241-52. [PMID: 24100034 DOI: 10.1074/jbc.m113.512087] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The Bcl-2 proapoptotic proteins Bax and Bak mediate the permeabilization of the mitochondrial outer membrane during apoptosis. Current models consider that Bax and Bak form pores at the mitochondrial outer membrane that are responsible for the release of cytochrome c and other larger mitochondrial apoptotic factors (i.e. Smac/DIABLO, AIF, and endoglycosidase G). However, the properties and nature of Bax/Bak apoptotic pores remain enigmatic. Here, we performed a detailed analysis of the membrane permeabilizing activity of Bax and Bak at the single vesicle level. We directly visualized that cBid-activated Bax and BakΔC21 can form membrane pores large enough to release not only cytochrome c, but also allophycocyanine, a protein of 104 kDa. Interestingly, the size of Bax and BakΔC21 pores is not constant, as typically observed in purely proteinaceous channels, but evolves with time and depends on protein concentration. We found that Bax and BakΔC21 formed long-lived pores, whose areas changed with the amount of Bax/BakΔC21 but not with cardiolipin concentration. Altogether, our results demonstrate that Bax and BakΔC21 follow similar mechanisms of membrane permeabilization characterized by the formation of protein-permeable pores of dynamic size, in agreement with the proteolipidic nature of these apoptotic pores.
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Affiliation(s)
- Stephanie Bleicken
- From the German Cancer Research Center, BioQuant, ImNeuenheimer Feld 267, 69120 Heidelberg, Germany
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