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Sathyanarayana P, Visweswariah SS, Ayappa KG. Mechanistic Insights into Pore Formation by an α-Pore Forming Toxin: Protein and Lipid Bilayer Interactions of Cytolysin A. Acc Chem Res 2021; 54:120-131. [PMID: 33291882 DOI: 10.1021/acs.accounts.0c00551] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Pore forming toxins (PFTs) are the largest class of bacterial toxins playing a central role in bacterial pathogenesis. They are proteins specifically designed to form nanochannels in the membranes of target cells, ultimately resulting in cell death and establishing infection. PFTs are broadly classified as α- and β-PFTs, depending on secondary structures that form the transmembrane channel. A unique feature about this class of proteins is the drastic conformational changes and complex oligomerization pathways that occur upon exposure to the plasma membrane. A molecular understanding of pore formation has implications in designing novel intervention strategies to combat rising antimicrobial resistance, targeted-cancer therapy, as well as designing nanopores for specialized technologies. Central to unraveling the pore formation pathway is the availability of high resolution crystal structures. In this regard, β-toxins are better understood, when compared with α-toxins whose pore forming mechanisms are complicated by an incomplete knowledge of the driving forces for amphiphatic membrane-inserted helices to organize into functional pores. With the publication of the first crystal structure for an α-toxin, cytolysin A (ClyA), in 2009 we embarked on an extensive multiscale study to unravel its pore forming mechanism. This Account represents the collective mechanistic knowledge gained in our laboratories using a variety of experimental and theoretical techniques which include large scale molecular dynamics (MD) simulations, kinetic modeling studies, single-molecule fluorescence imaging, and super-resolution spectroscopy. We reported MD simulations of the ClyA protomer, oligomeric intermediates, and full pore complex in a lipid bilayer and mapped the conformational transitions that accompany membrane binding. Using single-molecule fluorescence imaging, the conformational transition was experimentally verified by analysis of various diffusion states of membrane bound ClyA. Importantly, we have uncovered a hitherto unknown putative cholesterol binding motif in the membrane-inserted helix of ClyA. Distinct binding pockets for cholesterol formed by adjacent membrane-inserted helices are revealed in MD simulations. Cholesterol appears to play a dual role by stabilizing both the membrane-inserted protomer as well as oligomeric intermediates. Molecular dynamics simulations and kinetic modeling studies suggest that the membrane-inserted arcs oligomerize reversibly to form the predominant transmembrane oligomeric intermediates during pore formation. We posit that this mechanistic understanding of the complex action of α-PFTs has implications in unraveling pore assembly across the wider family of bacterial toxins. With emerging antimicrobial resistance, alternate therapies may rely on disrupting pore functionality or oligomerization of these pathogenic determinants utilized by bacteria, and our study includes assessing the potential for dendrimers as pore blockers.
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Affiliation(s)
- Pradeep Sathyanarayana
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India 560012
| | - Sandhya S. Visweswariah
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India 560012
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India 560012
| | - K. Ganapathy Ayappa
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India 560012
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, India 560012
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Shi S, Quarta N, Zhang H, Lu Z, Hof M, Šachl R, Liu R, Hoernke M. Hidden complexity in membrane permeabilization behavior of antimicrobial polycations. Phys Chem Chem Phys 2021; 23:1475-1488. [DOI: 10.1039/d0cp05651k] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
There are diverse membrane permeabilization behaviors of antimicrobial polycations in zwitterionic or charged vesicles; different mechanisms may occur over time.
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Affiliation(s)
- Shuai Shi
- Chemistry and Pharmacy
- Albert-Ludwigs-Universität
- 79104 Freiburg i.Br
- Germany
| | - Ndjali Quarta
- Chemistry and Pharmacy
- Albert-Ludwigs-Universität
- 79104 Freiburg i.Br
- Germany
- Department of Chemistry, Biochemistry
| | - Haodong Zhang
- State Key Laboratory of Bioreactor Engineering
- Frontiers Science Center for Materiobiology and Dynamic Chemistry
- School of Materials Science and Engineering
- East China University of Science and Technology
- Shanghai 200237
| | - Ziyi Lu
- State Key Laboratory of Bioreactor Engineering
- Frontiers Science Center for Materiobiology and Dynamic Chemistry
- School of Materials Science and Engineering
- East China University of Science and Technology
- Shanghai 200237
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences
- 182 23 Prague
- Czech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences
- 182 23 Prague
- Czech Republic
| | - Runhui Liu
- State Key Laboratory of Bioreactor Engineering
- Frontiers Science Center for Materiobiology and Dynamic Chemistry
- School of Materials Science and Engineering
- East China University of Science and Technology
- Shanghai 200237
| | - Maria Hoernke
- Chemistry and Pharmacy
- Albert-Ludwigs-Universität
- 79104 Freiburg i.Br
- Germany
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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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4
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Melittin-Induced Permeabilization, Re-sealing, and Re-permeabilization of E. coli Membranes. Biophys J 2019; 114:368-379. [PMID: 29401434 DOI: 10.1016/j.bpj.2017.10.046] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/18/2017] [Accepted: 10/26/2017] [Indexed: 11/21/2022] Open
Abstract
The permeabilization of model lipid bilayers by cationic peptides has been studied extensively over decades, with the bee-sting toxin melittin perhaps serving as the canonical example. However, the relevance of these studies to the permeabilization of real bacterial membranes by antimicrobial peptides remains uncertain. Here, we employ single-cell fluorescence microscopy in a detailed study of the interactions of melittin with the outer membrane (OM) and the cytoplasmic membrane (CM) of live Escherichia coli. Using periplasmic green fluorescent protein (GFP) as a probe, we find that melittin at twice the minimum inhibitory concentration first induces abrupt cell shrinkage and permeabilization of the OM to GFP. Within ∼4 s of OM permeabilization, the CM invaginates to form inward facing "periplasmic bubbles." Seconds later the bubbles begin to leak periplasmic GFP into the cytoplasm. Permeabilization is localized, consistent with possible formation of toroidal pores. Within ∼20 s, first the OM and then the CM re-seals to GFP. Some 2-20 min later, both CM and OM are re-permeabilized to GFP. We invoke a mechanism based on curvature stress concepts derived from model bilayer studies. The permeabilization and re-sealing events involve sequential, time-dependent build-up of melittin density within the outer and inner leaflets of each bilayer. We also propose a mechanical explanation for the early cell shrinkage event induced by melittin and a variety of other cationic peptides. As peptides gain access to the periplasm, they bind to the anionic peptido-crosslinks of the lipopolysaccharide layer, increasing its longitudinal elastic modulus. The cell wall shrinks because it can withstand the same turgor pressure with smaller overall extension. Shrinkage in turn induces invagination of the CM, preserving its surface area. We conclude by comparing the behavior of different peptides.
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Agrawal A, Apoorva K, Ayappa KG. Transmembrane oligomeric intermediates of pore forming toxin Cytolysin A determine leakage kinetics. RSC Adv 2017. [DOI: 10.1039/c7ra07304f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Leakage kinetics of Cytolysin A, an α pore forming toxin, occurs through stochastic insertion of oligomeric intermediates or ‘arcs’.
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Affiliation(s)
- Ayush Agrawal
- Department of Chemical Engineering
- Indian Institute of Science
- Bangalore-560012
- India
| | - K. Apoorva
- Department of Chemical Engineering
- Indian Institute of Technology
- Hyderabad-502205
- India
| | - K. G. Ayappa
- Department of Chemical Engineering
- Indian Institute of Science
- Bangalore-560012
- India
- Centre for Biosystems Science and Engineering
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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: 53] [Impact Index Per Article: 6.6] [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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Chulkov EG, Ostroumova OS. Phloretin modulates the rate of channel formation by polyenes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:289-94. [DOI: 10.1016/j.bbamem.2015.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 11/05/2015] [Accepted: 12/01/2015] [Indexed: 12/12/2022]
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8
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Tabaei SR, Rabe M, Zhdanov VP, Cho NJ, Höök F. Single vesicle analysis reveals nanoscale membrane curvature selective pore formation in lipid membranes by an antiviral α-helical peptide. NANO LETTERS 2012; 12:5719-5725. [PMID: 23092308 DOI: 10.1021/nl3029637] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Using tethered sub-100 nm lipid vesicles that mimic enveloped viruses with nanoscale membrane curvature, we have in this work designed a total internal reflection fluorescence microscopy-based single vesicle assay to investigate how an antiviral amphipathic α-helical (AH) peptide interacts with lipid membranes to induce membrane curvature-dependent pore formation and membrane destabilization. Based on a combination of statistics from single vesicle imaging, binding kinetics data, and theoretical analysis, we propose a mechanistic model that is consistent with the experimentally observed peptide association and pore formation kinetics at medically relevant peptide concentrations (10 nM to 1 μM) and unusually low peptide-to-lipid (P/L) ratio (~1/1000). Importantly, the preference of the AH peptide to selectively rupture virions with sub-100 nm diameters appears to be related to membrane strain-dependent pore formation rather than to previously observed nanoscale membrane curvature facilitated binding of AH peptides. Compared to other known proteins and peptides, the combination of low effective P/L ratio and high specificity for nm-sized membrane curvature lends this particular AH peptide great potential to serve as a framework for developing a highly specific and potent antiviral agent for prophylactic and therapeutic applications while avoiding toxic side effects against host cell membranes.
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Affiliation(s)
- Seyed R Tabaei
- Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden
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9
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Su CJ, Wu SS, Jeng US, Lee MT, Su AC, Liao KF, Lin WY, Huang YS, Chen CY. Peptide-induced bilayer thinning structure of unilamellar vesicles and the related binding behavior as revealed by X-ray scattering. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:528-34. [PMID: 23123565 DOI: 10.1016/j.bbamem.2012.10.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 10/22/2012] [Accepted: 10/26/2012] [Indexed: 11/18/2022]
Abstract
We have studied the bilayer thinning structure of unilamellar vesicles (ULV) of a phospholipid 1,2-dierucoyl-sn-glycero-3-phosphocholine (di22:1PC) upon binding of melittin, a water-soluble amphipathic peptide. Successive thinning of the ULV bilayers with increasing peptide concentration was monitored via small-angle X-ray scattering (SAXS). Results suggest that the two leaflets of the ULV of closed bilayers are perturbed and thinned asymmetrically upon free peptide binding, in contrast to the centro-symmetric bilayer thinning of the substrate-oriented multilamellar membranes (MLM) with premixed melittin. Moreover, thinning of the melittin-ULV bilayer associates closely with peptide concentration in solution and saturates at ~4%, compared to the ~8% maximum thinning observed for the correspondingly premixed peptide-MLM bilayers. Linearly scaling the thinning of peptide-ULV bilayers to that of the corresponding peptide-MLM of a calibrated peptide-to-lipid ratio, we have deduced the number of bound peptides on the ULV bilayers as a function of free peptide concentration in solution. The hence derived X-ray-based binding isotherm allows extraction of a low binding constant of melittin to the ULV bilayers, on the basis of surface partition equilibrium and the Gouy-Chapman theory. Moreover, we show that the ULV and MLM bilayers of di22:1PC share a same thinning constant upon binding of a hydrophobic peptide alamethicin; this result supports the linear scaling approach used in the melittin-ULV bilayer thinning for thermodynamic binding parameters of water-soluble peptides.
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Affiliation(s)
- Chun-Jen Su
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
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10
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Vachon V, Laprade R, Schwartz JL. Current models of the mode of action of Bacillus thuringiensis insecticidal crystal proteins: A critical review. J Invertebr Pathol 2012; 111:1-12. [DOI: 10.1016/j.jip.2012.05.001] [Citation(s) in RCA: 283] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 05/01/2012] [Accepted: 05/03/2012] [Indexed: 12/29/2022]
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11
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Sanderson JM. Resolving the kinetics of lipid, protein and peptide diffusion in membranes. Mol Membr Biol 2012; 29:118-43. [DOI: 10.3109/09687688.2012.678018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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12
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Shpasser D, Balazs YS, Kapon M, Sheynis T, Jelienk R, Eisen MS. A Paradigm for Solvent and Temperature Induced Conformational Changes. Chemistry 2011; 17:8285-9. [DOI: 10.1002/chem.201100339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 04/05/2011] [Indexed: 11/06/2022]
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13
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Won A, Pripotnev S, Ruscito A, Ianoul A. Effect of Point Mutations on the Secondary Structure and Membrane Interaction of Antimicrobial Peptide Anoplin. J Phys Chem B 2011; 115:2371-9. [DOI: 10.1021/jp108343g] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Amy Won
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| | - Stahs Pripotnev
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| | - Annamaria Ruscito
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| | - Anatoli Ianoul
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
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Mazzuca C, Orioni B, Coletta M, Formaggio F, Toniolo C, Maulucci G, De Spirito M, Pispisa B, Venanzi M, Stella L. Fluctuations and the rate-limiting step of peptide-induced membrane leakage. Biophys J 2011; 99:1791-800. [PMID: 20858423 DOI: 10.1016/j.bpj.2010.07.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 06/28/2010] [Accepted: 07/07/2010] [Indexed: 11/16/2022] Open
Abstract
Peptide-induced vesicle leakage is a common experimental test for the membrane-perturbing activity of antimicrobial peptides. The leakage kinetics is usually very slow, requiring minutes to hours for complete release of vesicle contents, and exhibits a biphasic behavior. We report here that, in the case of the peptaibol trichogin GA IV, all processes involved in peptide-membrane interaction, such as peptide-membrane association, peptide aggregation, and peptide translocation, take place on a timescale much shorter than the leakage kinetics. On the basis of these findings, we propose a stochastic model in which the leakage kinetics is determined by the discrete nature of a vesicle suspension: peptides are continuously exchanging among vesicles, producing significant fluctuations over time in the number of peptide molecules bound to each vesicle, and in the formation of pores. According to this model, the fast initial leakage is caused by vesicles that contain at least one pore after the peptides are randomly distributed among the liposomes, whereas the slower release is associated with the time needed to occasionally reach in an intact vesicle the critical number of bound peptides necessary for pore formation. Fluctuations due to peptide exchange among vesicles therefore represent the rate-limiting step of such a slow mechanism.
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Affiliation(s)
- C Mazzuca
- Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Rome, Italy
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15
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Leite NB, da Costa LC, Dos Santos Alvares D, Dos Santos Cabrera MP, de Souza BM, Palma MS, Ruggiero Neto J. The effect of acidic residues and amphipathicity on the lytic activities of mastoparan peptides studied by fluorescence and CD spectroscopy. Amino Acids 2010; 40:91-100. [PMID: 20195659 DOI: 10.1007/s00726-010-0511-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 02/03/2010] [Indexed: 11/27/2022]
Abstract
Some mastoparan peptides extracted from social wasps display antimicrobial activity and some are hemolytic and cytotoxic. Although the cell specificity of these peptides is complex and poorly understood, it is believed that their net charges and their hydrophobicity contribute to modulate their biological activities. We report a study, using fluorescence and circular dichroism spectroscopies, evaluating the influence of these two parameters on the lytic activities of five mastoparans in zwitterionic and anionic phospholipid vesicles. Four of these peptides, extracted from the venom of the social wasp Polybia paulista, present both acidic and basic residues with net charges ranging from +1 to +3 which were compared to Mastoparan-X with three basic residues and net charge +4. Previous studies revealed that these peptides have moderate-to-strong antibacterial activity against Gram-positive and Gram-negative microorganisms and some of them are hemolytic. Their affinity and lytic activity in zwitterionic vesicles decrease with the net electrical charges and the dose response curves are more cooperative for the less charged peptides. Higher charged peptides display higher affinity and lytic activity in anionic vesicles. The present study shows that the acidic residues play an important role in modulating the peptides' lytic and biological activities and influence differently when the peptide is hydrophobic or when the acidic residue is in a hydrophilic peptide.
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Affiliation(s)
- Natália Bueno Leite
- Department of Physics IBILCE, São Paulo State University, rua Cristóvão Colombo 2265, 15054-000, São José do Rio Preto, Brazil
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16
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Abstract
Measurement of binding and activity of antimicrobial and cytolytic amphipathic peptides on membranes is essential to understanding their function and cell specificity. The use of model systems has provided a wealth of information on the interactions of amphipathic peptides with membranes. Binding of peptides to membranes can be monitored by measuring Förster resonance energy transfer from a Trp residue on the peptide to a lipid fluorophore incorporated in the membrane. Especially for peptides that perturb or disrupt the membrane, it is advantageous to perform these measurements as a function of time, rather than in steady state. The activity of these amphipathic peptides toward model membranes is usually measured by dye efflux kinetics. One of those methods, based on self-quenching of carboxyfluorescein, is described here, together with a discussion of caveats and pitfalls of the corresponding analysis and interpretation.
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Affiliation(s)
- Paulo F Almeida
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC, USA
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Yandek LE, Pokorny A, Almeida PFF. Wasp mastoparans follow the same mechanism as the cell-penetrating peptide transportan 10. Biochemistry 2009; 48:7342-51. [PMID: 19594111 DOI: 10.1021/bi9008243] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have been examining the mechanism and kinetics of the interactions of a selected set of peptides with phospholipid membranes in a quantitative manner. This set was chosen to cover a broad range of physical-chemical properties and cell specificities. Mastoparan (masL) and mastoparan X (masX) are two similar peptides from the venoms of the wasps Vespula lewisii and Vespa xanthoptera, respectively, and were chosen to complete the set. The rate constants for masX association with and dissociation from membranes are reported here for the first time. The kinetics of dye efflux induced by both mastoparans from phospholipid vesicles were also examined and quantitatively analyzed. We find that masL and masX follow the same graded kinetic model that we previously proposed for the cell-penetrating peptide transportan 10 (tp10), but with different parameters. This comparison is relevant because tp10 is derived from masL by addition of a mostly nonpolar segment of seven residues at the N-terminus. Tp10 is more active than the mastoparans toward phosphatidylcholine vesicles, but the mastoparans are more sensitive to the effect of anionic lipids. Furthermore, the Gibbs free energies of binding and insertion of the peptides calculated using the Wimley-White transfer scales are in good agreement with the values derived from our experimental data and are useful for understanding peptide behavior.
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Affiliation(s)
- Lindsay E Yandek
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina 28403, USA
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18
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Szilluweit R, Boll A, Lukowski S, Gerlach H, Fackler OT, Geyer M, Steinem C. HIV-1 Nef perturbs artificial membranes: investigation of the contribution of the myristoyl anchor. Biophys J 2009; 96:3242-50. [PMID: 19383468 DOI: 10.1016/j.bpj.2008.12.3947] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 12/03/2008] [Accepted: 12/30/2008] [Indexed: 12/19/2022] Open
Abstract
Nef, an accessory protein from human immunodeficiency virus type 1, is critical for optimal viral replication and pathogenesis. Here, we analyzed the influence of full-length myristoylated and nonmyristoylated Nef on artificial lipid bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). By means of cosedimentation assays, we found that neither nonmyristoylated nor myristoylated Nef stably binds to POPC unilamellar vesicles. Time-resolved ellipsometry rather indicates that the proteins perturb the assembly of POPC planar bilayers. This observation was corroborated by fluorescence and scanning force microscopy, suggesting that membrane disordering occurs upon interaction of full-length myristoylated and nonmyristoylated Nef with planar POPC membranes immobilized on SiO(2) surfaces resulting in loss of material from the surface. The membrane perturbations were further investigated by vesicle release experiments, demonstrating that the disordering results in defects through which the fluorophor carboxyfluorescein can pass. From these results, we conclude that Nef is capable of disordering and perturbing lipid membranes and that the myristoyl group is not the decisive determinant for the action of the protein on lipid membranes.
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Affiliation(s)
- Ruth Szilluweit
- Institute of Organic and Biomolecular Chemistry, Georg-August University, 37077 Göttingen, Germany
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19
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Huang YH, Colgrave ML, Daly NL, Keleshian A, Martinac B, Craik DJ. The biological activity of the prototypic cyclotide kalata b1 is modulated by the formation of multimeric pores. J Biol Chem 2009; 284:20699-707. [PMID: 19491108 DOI: 10.1074/jbc.m109.003384] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cyclotides are a large family of circular mini-proteins containing a cystine knot motif. They are expressed in plants as defense-related proteins, with insecticidal activity. Here we investigate their role in membrane interaction and disruption. Kalata B1, a prototypic cyclotide, was found to induce leakage of the self-quenching fluorophore, carboxyfluorescein, from phospholipid vesicles. Alanine-scanning mutagenesis of kalata B1 showed that residues essential for lytic activity are clustered, forming a bioactive face. Kalata B1 was sequestered at the membrane surface and showed slow dissociation from vesicles. Electrophysiological experiments showed that conductive pores were induced in liposome patches on incubation with kalata B1. The conductance calculated from the current-voltage relationship indicated that the diameter of the pores formed in the bilayer patches is 41-47 A. Collectively, the findings provide a mechanistic explanation for the diversity of biological functions ascribed to this fascinating family of ultrastable macrocyclic peptides.
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Affiliation(s)
- Yen-Hua Huang
- Institute for Molecular Bioscience, The University of Queensland, Brisbane 4072, Australia
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20
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Brändén M, Dahlin S, Höök F. Label-Free Measurements of Molecular Transport across Liposome Membranes using Evanescent-Wave Sensing. Chemphyschem 2008; 9:2480-5. [DOI: 10.1002/cphc.200800614] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Harvey RD, Lawrence MJ, Bui TT. Probing the steric barrier of nonionic surfactant vesicles with melittin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2081-90. [DOI: 10.1016/j.bbamem.2008.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/24/2008] [Accepted: 04/07/2008] [Indexed: 10/22/2022]
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22
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23
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Literature Alerts. J Microencapsul 2008. [DOI: 10.3109/02652049109069569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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24
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Dalla Serra M, Cirioni O, Vitale RM, Renzone G, Coraiola M, Giacometti A, Potrich C, Baroni E, Guella G, Sanseverino M, De Luca S, Scalise G, Amodeo P, Scaloni A. Structural features of distinctin affecting peptide biological and biochemical properties. Biochemistry 2008; 47:7888-99. [PMID: 18597491 DOI: 10.1021/bi800616k] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The antimicrobial peptide distinctin consists of two peptide chains linked by a disulfide bridge; it presents a peculiar fold in water resulting from noncovalent dimerization of two heterodimeric molecules. To investigate the contribution of each peptide chain and the S-S bond to distinctin biochemical properties, different monomeric and homodimeric peptide analogues were synthesized and comparatively evaluated with respect to the native molecule. Our experiments demonstrate that the simultaneous occurrence of both peptide chains and the disulfide bond is essential for the formation of the quaternary structure of distinctin in aqueous media, able to resist protease action. In contrast, distinctin and monomeric and homodimeric analogues exhibited comparable antimicrobial activities, suggesting only a partial contribution of the S-S bond to peptide killing effectiveness. Relative bactericidal properties paralleled liposome permeabilization results, definitively demonstrating that microbial membranes are the main target of distinctin activity. Various biophysical experiments performed in membrane-mimicking media, before and after peptide addition, provided information about peptide secondary structure, lipid bilayer organization, and lipid-peptide orientation with respect to membrane surface. These data were instrumental in the generation of putative models of peptide-lipid supramolecular pore complexes.
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Affiliation(s)
- Mauro Dalla Serra
- Bruno Kessler Foundation, Institute of Biophysics, National Research Council, 38100 Povo, Trento, Italy
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25
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dos Santos Cabrera MP, Costa STB, de Souza BM, Palma MS, Ruggiero JR, Ruggiero Neto J. Selectivity in the mechanism of action of antimicrobial mastoparan peptide Polybia-MP1. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2008; 37:879-91. [DOI: 10.1007/s00249-008-0299-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 02/10/2008] [Accepted: 02/26/2008] [Indexed: 10/22/2022]
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26
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Danoff EJ, Wang X, Tung SH, Sinkov NA, Kemme AM, Raghavan SR, English DS. Surfactant vesicles for high-efficiency capture and separation of charged organic solutes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:8965-71. [PMID: 17658858 DOI: 10.1021/la070215n] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We demonstrate the unique ability of catanionic vesicles, formed by mixing single-tailed cationic and anionic surfactants, to capture ionic solutes with remarkable efficiency. In an initial study (Wang, X.; Danoff, E. J.; Sinkov, N. A.; Lee, J.-H.; Raghavan, S. R.; English, D. S. Langmuir 2006, 22, 6461) with vesicles formed from cetyl trimethylammonium tosylate (CTAT) and sodium dodecylbenzenesulfonate (SDBS), we showed that CTAT-rich (cationic) vesicles could capture the anionic solute carboxyfluorescein with high efficiency (22%) and that the solute was retained by the vesicles for very long times (t1/2 = 84 days). Here we expand on these findings by investigating the interactions of both anionic and cationic solutes, including the chemotherapeutic agent doxorubicin, with both CTAT-rich and SDBS-rich vesicles. The ability of these vesicles to capture and hold dyes is extremely efficient (>20%) when the excess charge of the vesicle bilayer is opposite that of the solute (i.e., for anionic solutes in CTAT-rich vesicles and for cationic solutes in SDBS-rich vesicles). This charge-dependent effect is strong enough to enable the use of vesicles to selectively capture and separate an oppositely charged solute from a mixture of solutes. Our results suggest that catanionic surfactant vesicles could be useful for a variety of separation and drug delivery applications because of their unique properties and long-term stability.
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Affiliation(s)
- Emily J Danoff
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-2111, USA
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27
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Andersson A, Danielsson J, Gräslund A, Mäler L. Kinetic models for peptide-induced leakage from vesicles and cells. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:621-35. [PMID: 17273853 DOI: 10.1007/s00249-007-0131-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 12/19/2006] [Accepted: 01/03/2007] [Indexed: 10/23/2022]
Abstract
In this article analytical expressions for peptide-induced membrane leakage are presented. Two different models for time-dependent leakage have been developed. In the first, the leakage is assumed to be coupled by pores formed by the peptides. In the second model the peptide is assumed to induce a stress/perturbation in the membrane, and in order to reduce the stress, rearrangements in the membrane are induced. The leakage is coupled to these rearrangements, and when equilibrium is achieved no more leakage occurs. From the kinetic models simple fitting routines have been developed involving only two fitting parameters, and these have been used to fit experimental data for two prion protein-derived peptides as well as the honey bee toxin melittin in both vesicles and erythrocytes with good results. The fitted parameters provide both a quantitative and a qualitative basis for interpreting the experimental results. In addition a model for the peptide concentration-dependent leakage is presented, which was used to fit experimental data for leakage induced by the prion protein-derived peptides. The models presented in this article are compared with other models for peptide-induced membrane leakage.
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Affiliation(s)
- August Andersson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories, Stockholm University, 106 91, Stockholm, Sweden
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28
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Silva L, Coutinho A, Fedorov A, Prieto M. Nystatin-induced lipid vesicles permeabilization is strongly dependent on sterol structure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:452-9. [PMID: 16626629 DOI: 10.1016/j.bbamem.2006.03.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 03/03/2006] [Accepted: 03/06/2006] [Indexed: 10/24/2022]
Abstract
The selectivity of the antibiotic nystatin towards ergosterol compared to cholesterol is believed to be a crucial factor in its specificity for fungi. In order to define the structural features of sterols that control this effect, nystatin interaction with ergosterol-, cholesterol-, brassicasterol- and 7-dehydrocholesterol-containing palmitoyloleoylphosphocholine vesicles was studied by fluorescence spectroscopy. Variations in sterol structure were correlated with their effect on nystatin photophysical and activity properties. Substitution of cholesterol by either 7-dehydrocholesterol or brassicasterol enhance nystatin ability to dissipate a transmembrane K+ gradient, showing that the presence of additional double bonds in these sterols-carbon C7 and C22, plus an additional methyl group on C-24, respectively-as compared to cholesterol, is fundamental for nystatin-sterol interaction. However, both modifications of the cholesterol molecule, like in the fungal sterol ergosterol, are critical for the formation of very compact nystatin oligomers in the lipid bilayer that present a long mean fluorescence lifetime and induce a very fast transmembrane dissipation. These observations are relevant to the molecular mechanism underlying the high selectivity presented by nystatin towards fungal cells (with ergosterol) as compared to mammalian cells (with cholesterol).
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Affiliation(s)
- Liana Silva
- CQFM, Complexo I, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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29
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Silva L, Coutinho A, Fedorov A, Prieto M. Competitive binding of cholesterol and ergosterol to the polyene antibiotic nystatin. A fluorescence study. Biophys J 2006; 90:3625-31. [PMID: 16500971 PMCID: PMC1440743 DOI: 10.1529/biophysj.105.075408] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Competition studies between cholesterol and ergosterol were carried out to gain insight into the binding interactions between nystatin and these sterols. Lipid vesicles were prepared with mixtures of palmitoyloleoylphosphocholine/ergosterol/cholesterol, and both sterol molar ratio and total content were varied. The inhibitory effect of cholesterol toward the ergosterol ability to induce the formation of long-lived fluorescent antibiotic species was used to detect nystatin-cholesterol interactions. It was found that the key factor controlling nystatin photophysical properties in the ternary lipid mixtures was their ergosterol/cholesterol molar ratio and not their overall sterol content. Moreover, permeabilization studies showed that nystatin was able to form pores in all the mixed vesicles, but the initial rate of pore formation was also dependent on the ergosterol/cholesterol molar ratio. Our data show that ergosterol is displaced by competing cholesterol, indirectly confirming cholesterol's ability to coassemble with nystatin. The distinct spectroscopic properties emphasize the different molecular architecture adopted by nystatin-cholesterol and -ergosterol complexes, and therefore are relevant to understanding the interaction of the antibiotic with membranes.
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Affiliation(s)
- Liana Silva
- CQFM, Instituto Superior Técnico, Lisbon, Portugal
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30
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Pokorny A, Almeida PFF. Kinetics of dye efflux and lipid flip-flop induced by delta-lysin in phosphatidylcholine vesicles and the mechanism of graded release by amphipathic, alpha-helical peptides. Biochemistry 2004; 43:8846-57. [PMID: 15236593 DOI: 10.1021/bi0497087] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Delta-lysin is a 26-residue, amphipathic, alpha-helical peptide of bacterial origin. Its specificity is to some extent complementary to that of antimicrobial peptides. Therefore, understanding its mechanism is important for the more general goal of understanding the interaction of amphipathic peptides with membranes. In this article, we show that delta-lysin induces graded efflux of the contents of phosphatidylcholine vesicles. In view of this finding, carboxyfluorescein efflux kinetics were re-examined. In addition, peptide-induced lipid flip-flop was directly measured using fluorescence energy transfer between two lipid fluorophores initially placed on opposite leaflets of the bilayer. Carboxyfluorescein efflux and lipid flip-flop occur with essentially identical rate constants. On the basis of a detailed, quantitative analysis of the kinetics of peptide-vesicle interactions, we conclude that the peptide translocates across the bilayer as a small, transient aggregate, most likely a trimer. Dye efflux and lipid flip-flop occur concomitantly with the transient peptide-induced perturbation of the membrane. The experimental data are interpreted by comparing the predictions of the available models for the mechanism of action of amphipathic alpha-helical peptides. We demonstrate how the combination of the quantitative kinetic analysis, graded efflux, and reversibility of the peptide-vesicle interaction can be used to reject several models for this particular peptide. Two models are compatible with the data, the toroidal pore model and the sinking raft model. On the basis of the small aggregate size, a trimer, the latter appears to be more plausible. Some significant modifications are introduced in the sinking raft model to take into account the new finding of graded dye release. Furthermore, we present an explanation for the phenomenon of graded release in general, which, contrary to all-or-none efflux, has not been well-understood.
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Affiliation(s)
- Antje Pokorny
- Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, North Carolina 28403, USA
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31
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Coutinho A, Silva L, Fedorov A, Prieto M. Cholesterol and ergosterol influence nystatin surface aggregation: relation to pore formation. Biophys J 2004; 87:3264-76. [PMID: 15315952 PMCID: PMC1304795 DOI: 10.1529/biophysj.104.044883] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nystatin interaction with liposomes mimicking fungal and mammalian membranes (ergosterol- and cholesterol-containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) large unilamellar vesicles, respectively) was studied by fluorescence spectroscopy. The activity of this antibiotic was also measured using a pyranine fluorescence detected K+/H+ exchange assay. Nystatin mean fluorescence lifetime varied with the antibiotic concentration and ergosterol content (0-30 mol%) of the lipid vesicles. It sharply increased from 5 to 37 ns upon reaching 100 molecules per liposome, reporting nystatin oligomerization in the membrane. Concomitantly, spectral alterations typical of excitonic coupling were detected and there was a pronounced increase in the initial rate of pore formation by nystatin. These findings suggest that nystatin exerts its antibiotic activity via a two-stage mechanism: at low antibiotic concentrations, surface-adsorbed monomeric antibiotic molecules perturb the lipid packing, changing the permeability properties of the ergosterol-rich liposomes. Upon reaching a critical threshold, nystatin mode of action switches to the classical model of transmembrane aqueous channel formation. In the presence of cholesterol-containing POPC liposomes, neither nystatin spectroscopic properties, nor the kinetics of K+ efflux varied with the antibiotic concentration suggesting that in this case the first stage of antibiotic mode of action always prevails or the assemblies formed by nystatin and cholesterol are very loose.
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Affiliation(s)
- Ana Coutinho
- Centro de Química-Física Molecular, Instituto Superior Técnico, P-1049-001 Lisbon, Portugal.
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32
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Affiliation(s)
- Mauro Dalla Serra
- CMR-ITC Institute of Biophysics, Section at Trento, Via Sommarive 18, Povo, Trento 38050, Italy
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33
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Tachi T, Epand RF, Epand RM, Matsuzaki K. Position-dependent hydrophobicity of the antimicrobial magainin peptide affects the mode of peptide-lipid interactions and selective toxicity. Biochemistry 2002; 41:10723-31. [PMID: 12186559 DOI: 10.1021/bi0256983] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cationic antimicrobial peptides are promising candidates as novel antibiotics of clinical usefulness. Magainin 2, a representative antimicrobial peptide isolated from the skin of the African clawed frog Xenopus leavis, electrostatically recognizes anionic lipids that are abundant in bacterial membranes, forming a peptide-lipid supramolecular complex pore, whereas the peptide does not effectively bind to zwitterionic phospholipids constituting the outer leaflets of mammalian cell membranes because of the low hydrophobicity of the peptide [Matsuzaki, K. (1999) Biochim. Biophys. Acta 1462, 1-10]. In this study, two magainin analogues with enhanced hydrophobicity, MG-H1 (GIKKFLHIIWKFIKAFVGEIMNS) and MG-H2 (IIKKFLHSIWKFGKAFVGEIMNI), with identical amino acid compositions were designed and interactions with lipid bilayers and biological activities were examined in comparison with those of MG (GIGKWLHSAKKFGKAFVGEIMNS = F5W-magainin 2). The apparent hydrophobicities and hydrophobic moments of MG-H1 and MG-H2, conventionally calculated assuming that all residues are involved in helix formation, were almost the same. MG-H2 behaved like MG except for greatly enhanced activity against zwitterionic membranes and erythrocytes. In contrast, despite a very similar calculated hydrophobicity, the observed hydrophobicity of MG-H1 was larger than that of MG-H2 because of a tendency toward helix fraying near the termini. Therefore, the physicochemical parameters of only the helical portion should be considered in characterizing peptide-lipid interactions, although this point was overlooked in most studies. Moreover, MG-H1 induced aggregation and/or fusion of negatively charged membranes. Furthermore, the peptide hydrophobicity was found to affect pore formation rate, pore size, and pore stability. These observations demonstrate that the hydrophobicity of the peptide also controls the mode of action and is dependent on the position of the hydrophobic amino acids in the peptide sequence.
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Affiliation(s)
- Tomoya Tachi
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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34
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Montes LR, Ruiz-Argüello MB, Goñi FM, Alonso A. Membrane restructuring via ceramide results in enhanced solute efflux. J Biol Chem 2002; 277:11788-94. [PMID: 11796726 DOI: 10.1074/jbc.m111568200] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The capacity of ceramides to modify the permeability barrier of cell membranes has been explored. Membrane efflux induced either by in situ generated ceramides (through enzymatic cleavage of sphingomyelin) or by addition of ceramides to preformed membranes has been studied. Large unilamellar vesicles composed of different phospholipids and cholesterol, and containing entrapped fluorescent molecules, have been used as a system to assay ceramide-dependent efflux. Small proportions of ceramide (10 mol % of total lipid) that may exist under physiological conditions of ceramide-dependent signaling have been used in most experiments. When long chain (egg-derived) ceramides are used, both externally added or enzymatically produced ceramides induce release of vesicle contents. However, the same proportion of ceramides generated by sphingomyelinase induce faster and more extensive efflux than when added in organic solution to the preformed vesicles. Under our conditions 10 mol % of N-acetylsphingosine (C(2)-ceramide) did not induce any efflux. On the other hand, sphingomyelinase treatment of bilayers containing 50 mol % sphingomyelin gave rise to release of fluorescein-derivatised dextrans of molecular mass approximately 20 kDa, i.e. larger than cytochrome c. These results have been discussed in the light of our own previous data (Ruiz-Argüello, M. B., Basañez, G., Goñi, F. M., and Alonso, A. (1996) J. Biol. Chem. 271, 26616-26621) and of the observations by Siskind and Colombini (Siskind, L. J., and Colombini, M. (2000) J. Biol. Chem. 275, 38640-38644). Our spectroscopic observations appear to be in good agreement with the electrophysiological studies of the latter authors. Furthermore, some experiments in this paper have been designed to explore the mechanism of ceramide-induced efflux. Two properties of ceramide, namely its capacity to induce negative monolayer curvature and its tendency to segregate into ceramide-rich domains, appear to be important in the membrane restructuring process.
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Affiliation(s)
- L Ruth Montes
- Unidad de Biofisica (Centro Mixto Consejo Superior de Investigaciones Cientificas/Universidad del Pais Vasco/Euskal Herriko Unibertsitatea) Bilbao, Spain
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35
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Hara T, Kodama H, Kondo M, Wakamatsu K, Takeda A, Tachi T, Matsuzaki K. Effects of peptide dimerization on pore formation: Antiparallel disulfide-dimerized magainin 2 analogue. Biopolymers 2001; 58:437-46. [PMID: 11180056 DOI: 10.1002/1097-0282(20010405)58:4<437::aid-bip1019>3.0.co;2-i] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To elucidate the effects of peptide dimerization on pore formation by magainin 2 (MG2), a covalently linked antiparallel dimer of the MG2 analogue [(F5Y, L6C, F16W, I20C-MG2)(2): II] was synthesized based on the dimer structure revealed by our NMR study. The interactions of the dimer with lipid bilayers were investigated by CD and fluorescence in comparison with a monomer analogue (F5Y, F16W-MG2: I). Similar to I, II was found to form a peptide-lipid supramolecular complex pore accompanied with lipid flip-flop and peptide translocation. The pore formed by II was characterized by a slightly larger pore diameter and a threefold longer lifetime than that of I, although the pore formation rate of the dimer was lower than that of the monomer. The coexistence of the dimer and the monomer exhibited slight but significant synergism in membrane permeabilization, which was maximal at a monomer/dimer ratio of 3. Therefore, we concluded that a pentameric pore composed of one pore-stabilizing dimer and three monomers maximized the overall leakage activity in keeping with our kinetic prediction.
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Affiliation(s)
- T Hara
- Department of Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
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36
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Uematsu N, Matsuzaki K. Polar angle as a determinant of amphipathic alpha-helix-lipid interactions: a model peptide study. Biophys J 2000; 79:2075-83. [PMID: 11023911 PMCID: PMC1301097 DOI: 10.1016/s0006-3495(00)76455-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Various physicochemical properties play important roles in the membrane activities of amphipathic antimicrobial peptides. To examine the effects of the polar angle, two model peptides, thetap100 and thetap180, with polar angles of 100 degrees and 180 degrees, respectively, were designed, and their interactions with membranes were investigated in detail. These peptides have almost identical physicochemical properties except for polar angle. Like naturally occurring peptides, these peptides selectively bind to acidic membranes, assuming amphipathic alpha-helices, and formed peptide-lipid supramolecular complex pores accompanied by lipid flip-flop and peptide translocation. Despite its somewhat lower membrane affinity, thetap100 exhibited higher membrane permeabilization activity, a greater flip-flop rate, as well as more antimicrobial activity due to a higher pore formation rate compared with thetap180. Consistent with these results, the peptide translocation rate of thetap100 was higher. Furthermore, the number of peptides constituting thetap100 pores was less than that of thetap180, and thetap100 pores involved more lipid molecules, as reflected by its cation selectivity. The polar angle was found to be an important parameter determining peptide-lipid interactions.
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Affiliation(s)
- N Uematsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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37
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Saito M, Korsmeyer SJ, Schlesinger PH. BAX-dependent transport of cytochrome c reconstituted in pure liposomes. Nat Cell Biol 2000; 2:553-5. [PMID: 10934477 DOI: 10.1038/35019596] [Citation(s) in RCA: 345] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- M Saito
- Department of Physiology and Cell Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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38
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Thomas JL, Tirrell1 DA. Polymer-induced leakage of cations from dioleoyl phosphatidylcholine and phosphatidylglycerol liposomes. J Control Release 2000; 67:203-9. [PMID: 10825554 DOI: 10.1016/s0168-3659(00)00209-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The amphipathic polyacid, poly(2-ethylacrylic acid) (PEAA) has recently been shown to form fluctuating channels in patch-clamp measurements of phospholipid bilayers ¿J.C. Chung, D.J. Gross, J.L. Thomas, D.A. Tirrell, L.R. Opsahl-Ong, Macromolecules 29 (1996) 4636-4641.. To explore this phenomenon further, we have quantified the PEAA-mediated pH-dependent release of sodium and calcium ions from phospholipid vesicles. Permeability to calcium increases linearly with polymer concentration and exponentially with decreasing pH. Permeabilization of negatively charged phosphatidylglycerol (PG) liposomes occurs to a similar extent and with a similar pH dependence to that of zwitterionic phosphatidylcholine (PC) liposomes, implying that a charge neutral species is responsible for the leakage. The pH dependence of leakage shows that the cooperative protonation of from three to five carboxylate anions is required for permeabilization. Such neutralization could result in a neutral segment of polymer chain of sufficient length to span the bilayer.
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Affiliation(s)
- J L Thomas
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA
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39
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Abstract
Leakage from liposomes induced by several peptides is reviewed and a pore model is described. According to this model peptide molecules become incorporated into the vesicle bilayer and aggregate reversibly or irreversibly within the surface. When a peptide aggregate reaches a critical size, peptide translocation can occur and a pore is formed. With the peptide GALA the pores are stable and persist for at least 10 minutes. The model predicts that for a given lipid/peptide ratio, the extent of leakage should decrease as the vesicle diameter decreases, and for a given amount of peptide bound per vesicle less leakage would be observed at higher temperatures due to the increase in reversibility of surface aggregates of the peptide. Effect of membrane composition on pore formation is reviewed. When cholesterol was included in the liposomes the efficiency of inducation of leakage by the peptide GALA was reduced due to reduced binding and increased reversibility of surface aggregation of the peptide. Phospholipids which contain less ordered acyl-chains and have a slightly wedge-like shape, can better accommodate peptide surface aggregates, and consequently insertion and translocation of the peptide may be less favored. Demonstrations of antagonism between pore formation and fusion are presented. The choice of factors which promote vesicle aggregation, e.g., larger peptides, increased vesicle and peptide concentration results in enhanced vesicle fusion at the expense of formation of intravesicular pores. FTIR studies with HIV-1 fusion peptides indicate that in systems where extensive vesicle fusion occurred the beta conformation of the peptides was predominant, whereas the alpha conformation was exhibited in cases where leakage was the main outcome. Antagonism between leakage and fusion was exhibited by 1-palmitoyl-2-oleoylphosphatidylglycerol vesicles, where the order of addition of peptide (HIV(arg)) or Ca(2+)dictated whether pore formation or vesicle fusion would occur. The current study emphasizes that the addition of Ca(2+), which promotes vesicle aggregation can also reduce peptide translocation in isolated vesicles.
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Affiliation(s)
- S Nir
- Seagram Center for Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, Rehovot, Israel.
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40
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Bechinger B. The structure, dynamics and orientation of antimicrobial peptides in membranes by multidimensional solid-state NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1462:157-83. [PMID: 10590307 DOI: 10.1016/s0005-2736(99)00205-9] [Citation(s) in RCA: 397] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Linear peptide antibiotics have been isolated from amphibians, insects and humans and used as templates to design cheaper and more potent analogues for medical applications. Peptides such as cecropins or magainins are < or = 40 amino acids in length. Many of them have been prepared by solid-phase peptide synthesis with isotopic labels incorporated at selected sites. Structural analysis by solid-state NMR spectroscopy and other biophysical techniques indicates that these peptide antibiotics strongly interact with lipid membranes. In bilayer environments they exhibit amphipathic alpha-helical conformations and alignments of the helix axis parallel to the membrane surface. This contrasts the transmembrane orientations observed for alamethicin or gramicidin A. Models that have been proposed to explain the antibiotic and pore-forming activities of membrane-associated peptides, as well as other experimental results, include transmembrane helical bundles, wormholes, carpets, detergent-like effects or the in-plane diffusion of peptide-induced bilayer instabilities.
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Affiliation(s)
- B Bechinger
- Max Planck Institute for Biochemistry, Am Klopferspitz 18A, 82152, Martinsried, Germany.
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41
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Silberstein A, Mirzabekov T, Anderson WF, Rozenberg Y. Membrane destabilization assay based on potassium release from liposomes. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1461:103-12. [PMID: 10556492 DOI: 10.1016/s0005-2736(99)00152-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inorganic ions are highly suitable markers for monitoring release of the inner content of liposomes. In the present study, a potassium (K(+)) selective electrode was used to evaluate the rate of K(+) release from large unilamellar vesicles (LUV). The developed method is highly sensitive, reproducible and inexpensive. Since the K(+) ion is smaller than other markers conventionally used, the method described is more sensitive than one of the standard methods that uses ANTS/DPX. In addition, the method allows us to expand the set of molecules used as inner content markers to a lower size range. The experimental protocol we described contains improvements on the method of Breukink et al. (Biochemistry, 36 (1997) 6968). Our developed method was applied to compare the destabilizing activities of two amphipathic peptides of natural origin (Melittin and HIV env seg I, 827-851) and of two artificial peptides (Hels 7:11 and 9:9) synthesized de novo by Kiyota et al. (Biochemistry, 35 (1996) 13196). The tested peptides released 20% of the liposomal K(+) in 1 min at peptide-to-lipid ratio of a few mmol per mol of total lipids (LUV sized to 0.2 micrometer, molar composition is POPC:POPS:Chol 2:2:1).
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Affiliation(s)
- A Silberstein
- Gene Therapy Laboratories, School of Medicine, University of Southern California, 1441 EastLake Ave., Room 610, Los Angeles, CA, USA
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42
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Arbuzova A, Schwarz G. Pore-forming action of mastoparan peptides on liposomes: a quantitative analysis. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1420:139-52. [PMID: 10446298 DOI: 10.1016/s0005-2736(99)00098-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We have investigated the wasp venom peptides mastoparan X and polistes mastoparan regarding their apparent potential to induce pore-like defects in phosphatidylcholine unilamellar vesicles. Based on a fundamental theoretical model, the pore activation and deactivation kinetics have been evaluated from the observed efflux of liposome entrapped carboxyfluorescein in relation to the bound peptide to lipid ratio. We can quantitatively describe our experimental data very well in terms of a specific reaction scheme resulting in only a few short-lived pores. They evidently emerge rapidly from a prepore nucleus being produced by two rate-limiting monomeric states of bound peptide. These peculiar states would be favorably populated in an early stage of bilayer perturbation, but tend to die out in the course of a peptide/lipid restabilization process.
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Affiliation(s)
- A Arbuzova
- Department of Biophysical Chemistry, Biocenter of the University of Basle, Klingelbergstrasse 70, CH-4056, Basle, Switzerland
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43
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Nir S, Nicol F, Szoka FC. Surface aggregation and membrane penetration by peptides: relation to pore formation and fusion. Mol Membr Biol 1999; 16:95-101. [PMID: 10332743 DOI: 10.1080/096876899294814] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The peptide GALA undergoes a conformational change to an amphipathic alpha-helix when the pH is reduced, inducing leakage of contents from vesicles. Leakage from neutral or negatively-charged vesicles at pH 5.0 was similar and could be adequately explained by a mathematical model which assumed that GALA becomes incorporated into the vesicle bilayer and irreversibly aggregates to form a pore consisting of M = 10 +/- 2 peptides. Increasing cholesterol content in the membranes resulted in reduced leakage, and increased reversibility of surface aggregation of the peptide. Employing fluorescently labelled peptides confirmed that the degree of reversibility of surface aggregation of GALA was significantly larger in cholesterol containing liposomes. Orientation of the peptide GALA in bilayers was determined by a bodipy-avidin/biotin binding assay. The peptide was labelled by biotin at the N- or C-terminus and bodipy-avidin molecules were added externally or were preencapsulated in the vesicles. The peptides are arranged in the pore perpendicularly to the membrane, such that 3/4 of the N-termini are on the internal side of the membrane. The pores are stable and persist for at least 10 min. When the peptides form an aggregate of size smaller than M, the orientation of the peptide is mostly parallel to the surface and the biotinylated peptide does not translocate. When a critical size of the aggregate is attained, a rearrangement of the peptide occurs, which amounts to rapid penetration and formation of a pore structure. Induction of fusion by peptides may be antagonistic to pore formation, the outcome being dependent on vesicle aggregation.
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Affiliation(s)
- S Nir
- Seagram Center for Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, Rehovot, Israel.
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44
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Rex S, Schwarz G. Quantitative studies on the melittin-induced leakage mechanism of lipid vesicles. Biochemistry 1998; 37:2336-45. [PMID: 9485380 DOI: 10.1021/bi971009p] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have investigated, both experimentally and theoretically, the efflux of carboxyfluorescein (a self-quenching fluorescent dye) from vesicles of different sizes and lipid species (POPC, DOPC) after having added the bee venom peptide melittin. This comprises quantitative analyses regarding the extent of lipid-associated peptide, the mode as well as the temporal progress of dye release and the possible leakage mechanism. Our results indicate a graded efflux characterized by a single-pore retention factor reflecting the formation of pores whose lifetimes are rather small (millisecond range). The observed fluorescence signal arising from the dequenching of effluent dye has been converted to the number of pore openings over the course of time. All the resulting curves exhibit a pronounced slowing down of the pore formation rate revealing two distinct relaxation steps at about 20 and 200 s, respectively, being largely independent of vesicle type and peptide to lipid ratio. The pore formation rate itself increases in proportion to the amount of membrane bound peptide. We give a quantitative account of our experimental findings based on a novel reaction scheme applicable to any of our various liposome systems. It implies that the pore formation rate is controlled by a passage through two intermediate monomeric peptide states. These states are thought to become well populated in the initial stage of lipid bilayer perturbation, but would practically die out after some time owing to a restabilization of the membrane system.
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Affiliation(s)
- S Rex
- Department of Biophysical Chemistry, Biocenter of the University of Basel, Basel, Switzerland
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45
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Kumar TK, Jayaraman G, Lee CS, Arunkumar AI, Sivaraman T, Samuel D, Yu C. Snake venom cardiotoxins-structure, dynamics, function and folding. J Biomol Struct Dyn 1997; 15:431-63. [PMID: 9439993 DOI: 10.1080/07391102.1997.10508957] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Snake cardiotoxins are highly basic (pI > 10) small molecular weight (approximately 6.5 kDa), all beta-sheet proteins. They exhibit a broad spectrum of interesting biological activities. The secondary structural elements in these toxins include antiparallel double and triple stranded beta-sheets. The three dimensional structures of these toxins reveal an unique asymmetric distribution of the hydrophobic and hydrophilic amino acids. The 3D structures of closely related snake venom toxins such as neurotoxins and cardiotoxin-like basic proteins (CLBP) fail to show similar pattern(s) in the distribution of polar and nonpolar residues. Recently, many novel biological activities have been reported for cardiotoxins. However, to-date, there is no clear structure-function correlation(s) available for snake venom cardiotoxins. The aim of this comprehensive review is to summarize and critically evaluate the progress in research on the structure, dynamics, function and folding aspects of snake venom cardiotoxins.
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Affiliation(s)
- T K Kumar
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
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46
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Mayhew E, Ahmad I, Bhatia S, Dause R, Filep J, Janoff AS, Kaisheva E, Perkins WR, Zha Y, Franklin JC. Stability of association of 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine with liposomes is composition dependent. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1329:139-48. [PMID: 9370251 DOI: 10.1016/s0005-2736(97)00102-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The ether lipid, 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine (ET-18-OCH3), has anticancer activity, but it has serious side-effects, including hemolysis, which prevent its optimal use. We surmised if ET-18-OCH3 could be stably associated with liposomes, less free ET-18-OCH3 would be available for lytic interaction with red cells. Liposome composition variables investigated included acyl chain saturation, phospholipid head group and mole ratio of Chol and ET-18-OCH3. It was found that attenuation of hemolysis was strongly liposome composition dependent. Some ET-18-OCH3 liposome compositions were minimally hemolytic. For example, whereas the HI5 (drug concentration required to cause 5% human red cell lysis) was 5-6 microM for free ET-18-OCH3, it was approximately 250 microM for DOPC (dioleoylphosphatidylcholine):Chol (cholesterol):DOPE-GA (glutaric acid derivatized DOPE):ET-18-OCH3, (4:3:1:2) and 640 microM for DOPE (dioleyolphosphatidylethanolamine):Chol:DOPE-GA:ET-18-OCH3 (4:3:1:2) liposomes. Efflux of carboxyfluorescein (CF) from liposomes and Langmuir trough determinations of mean molecular area of lipids in monolayers (MMAM) were used as indicators of membrane packing and stability. Incorporation of ET-18-OCH3 in liposomes reduced the MMAM. Reduction in CF permeation was correlated with reduction in hemolysis. The most stable liposomes included components, such as cholesterol, DOPC and DOPE, which have complementary shapes to ET-18-OCH3.
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Affiliation(s)
- E Mayhew
- The Liposome Company Inc., Princeton Forrestal Center, NJ 08540-6619, USA
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47
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Rochel N, Cowan JA. Dependence of the lytic activity of the N-terminal domain of human perforin on membrane lipid composition--implications for T-cell self-preservation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 249:223-31. [PMID: 9363773 DOI: 10.1111/j.1432-1033.1997.00223.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The kinetics and thermodynamics of pore formation by the 22-residue N-terminal domain of human perforin-(1-22)-peptide have been studied for a variety of model phospholipid membranes. Peptide binding and aggregation, and cell lysis were monitored through the change in the fluorescence of Trp, or vesicle-encapsulated carboxyfluorescein, respectively. Peptide binding was analyzed in terms of a model that incorporates non-ideal interactions and aggregation in a membrane bilayer. The minimum number of peptide monomers required to form an active pore averaged from four to six, according to the lipid composition of the vesicle. This combined kinetic and thermodynamic approach has provided quantitative information that allows a direct comparison of the binding behavior of the perforin-(1-22)-peptide in different lipid vesicles and affords molecular insight on the factors controlling pore formation. Pore formation is most favorable in thinner membranes with low melting temperatures. No significant difference in activity is observed for different zwitterionic headgroups. Rather, the gel state of the lipid chain, which diminishes the incorporation and aggregation of the perforin-(1-22)-peptide shows the strongest influence. This effect is observed in both the thermodynamic (incorporation isotherm) and kinetic (carboxyfluorescein release) studies. Insertion and aggregation are more facile in membranes with less densely packed lipids. The dependence of pore-forming activity on lipid composition provides important clues to understanding the self-protection mechanism employed by cytotoxic T lymphocytes (CTL) against perforin-mediated lysis.
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Affiliation(s)
- N Rochel
- Evans Laboratory of Chemistry, The Ohio State University, Columbus 43210, USA
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48
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Polozov IV, Polozova AI, Tytler EM, Anantharamaiah GM, Segrest JP, Woolley GA, Epand RM. Role of lipids in the permeabilization of membranes by class L amphipathic helical peptides. Biochemistry 1997; 36:9237-45. [PMID: 9230057 DOI: 10.1021/bi970045l] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We studied the mechanism of membrane permeabilization by the 18L model peptide (GIKKFLGSIWKFIKAFVG), which features the consensus class L sequence averaged from the number of naturally occurring lytic peptides. Two aspects of membrane lipid composition significantly affected peptide-membrane interactions: the presence of acidic lipids and, in zwitterionic membranes, and the presence of nonbilayer forming lipids. In zwitterionic membranes, 18L peptide destabilizes the membrane, leading to a transient formation of large defects in the membrane which result generally in contents leakage, but in the presence of bilayer-bilayer contact can alternatively lead to vesicle fusion. In membranes containing acidic lipids (DOPC:DOPG, DOPG), 18L caused leakage but not fusion, probably due to mutual repulsion of acidic vesicles. While the extent of contents leakage was approximately the same as for zwitterionic membranes, the kinetics of leakage could be resolved only by using stopped-flow, leakage being essentially complete within the first minute. Previously, we reported that apolipoprotein (class A) and lytic (class L) peptide analogs have opposing effects on some properties of biological membranes. This reciprocal effect of 18L and Ac-18A-NH2, class A model peptide, is restricted to membranes with a high propensity for nonbilayer phase formation (DOPE, Me-DOPE, DOPC:DOPE, DOPC:Me-DOPE). The decrease in the content of nonbilayer phase forming lipid or the addition of acidic lipids reduces or eliminates the reciprocal effects. This suggests the importance of nonbilayer phase propensity for certain functions of biological membranes.
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Affiliation(s)
- I V Polozov
- Department of Biochemistry, McMaster University Health Sciences Center, 1200 Main St. West, Hamilton, Ontario L8N 3Z5, Canada
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49
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Nicol F, Nir S, Szoka FC. Effect of cholesterol and charge on pore formation in bilayer vesicles by a pH-sensitive peptide. Biophys J 1996; 71:3288-301. [PMID: 8968598 PMCID: PMC1233816 DOI: 10.1016/s0006-3495(96)79521-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The effect of cholesterol on the bilayer partitioning of the peptide GALA (WEAALAEALAEALAEHLAEALAEALEALAA) and its assembly into a pore in large unilamellar vesicles composed of neutral and negatively charged phospholipids has been determined. GALA undergoes a conformational change from a random coil to an amphipathic alpha-helix when the pH is reduced from 7.0 to 5.0, inducing at low pH leakage of contents from vesicles. Leakage from neutral or negatively charged vesicles at pH 5.0 was similar and could be adequately explained by the mathematical model (Parente, R. A., S. Nir, and F. C. Szoka, Jr., 1990. Mechanism of leakage of phospholipid vesicle contents induced by the peptide GALA. Biochemistry. 29:8720-8728) which assumed that GALA becomes incorporated into the vesicle bilayer and irreversibly aggregates to form a pore consisting of 10 +/- 2 peptides. Increasing cholesterol content in the membranes resulted in a reduced efficiency of the peptide to induce leakage. Part of the cholesterol effect was due to reduced binding of the peptide to cholesterol-containing membranes. An additional effect of cholesterol was to increase reversibility of surface aggregation of the peptide in the membrane. Results could be explained and predicted with a model that retains the same pore size, i.e., 10 +/- 2 peptides, but includes reversible aggregation of the monomers to form the pore. Resonance energy transfer experiments using fluorescently labeled peptides confirmed that the degree of reversibility of surface aggregation of GALA was significantly larger in cholesterol-containing liposomes, thus reducing the efficiency of pore formation.
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Affiliation(s)
- F Nicol
- University of California, School of Pharmacy, Department of Biopharmaceutics, San Francisco 94143-0446, USA
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50
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Tejuca M, Serra MD, Ferreras M, Lanio ME, Menestrina G. Mechanism of membrane permeabilization by sticholysin I, a cytolysin isolated from the venom of the sea anemone Stichodactyla helianthus. Biochemistry 1996; 35:14947-57. [PMID: 8942660 DOI: 10.1021/bi960787z] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Actinaria cytolysins are very potent basic toxins isolated from the venom of sea anemones, which are supposed to exert their toxic activity through formation of oligomeric pores in the host plasma membrane. To gain insight into their mechanism of action, the interaction of Stichodactyla helianthus sticholysin I (St-I) with lipid bilayers was studied. St-I increased the permeability of calcein-loaded lipid vesicles composed of different phospholipids. The rate of permeabilization improved when sphingomyelin (SM) was introduced into phosphatidylcholine (PC) vesicles, reaching an optimum value at equimolar concentrations of these two phospholipids. It was also a function of the pH, showing a local maximum of activity between pH 8 and 9 and a marked decrease at pH 10 and 11. Under optimal conditions (e.g., PC:SM 1:1, pH 8, toxin to vesicle ratio < 200), most of the toxin is bound to the lipid phase. The reduced toxin effect at low and high SM content, or at high pH, is principally due to a decreased toxin binding. From the dose dependence of the permeabilization, at constant lipid concentration, it was inferred that St-I increases membrane permeability by forming oligomeric pores comprising at least three cytolysin monomers. The involvement of oligomers was also suggested by the dependence of calcein release on the vesicle concentration at constant toxin dose. In fact, the time course of dye release was well described under all circumstances by a kinetic model which assumes that trimerization leads to a conductive pore. All the relevant equilibrium and rate constants were derived. Addition of St-I to one side of a planar lipid membrane increased the conductivity of the film in discrete steps of defined amplitude, indicating the formation of ion channels. The dose dependence of this effect was the same as with LUV. The channel was cation-selective and its conductance suggested a functional radius of about 1.0 nm, consistent with the size of the lesion previously observed in red blood cells. Pores exhibited rectification and voltage-dependent gating.
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Affiliation(s)
- M Tejuca
- Centro di Fisica degli Stati Aggregati, Consiglio Nazionale delle Richerche-Istituto Trentino di Cultura, Povo (Trento), Italy
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