1
|
Lu S, Lin J, Jin J, Zhang L, Guan Y, Chen H, Wu Y, Zhang W, Luan X. Tachyplesin I and its derivatives: A pharmaco-chemical perspective on their antimicrobial and antitumor potential. Expert Opin Drug Discov 2022; 17:1407-1423. [PMID: 36503335 DOI: 10.1080/17460441.2023.2157402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Increasing evidence suggests that intratumor microbiota are an intrinsic component in the tumor microenvironment across multiple cancer types, and that there is a close relationship between microbiota and tumor progression. Therefore, how to address the interaction between bacteria and malignances has become a growing concern. Tachyplesin I (TPI), a peptide with dual antimicrobial and antitumor effects, holds great promise as a therapeutic alternative for the aforementioned diseases, with the advantage of broad-spectrum activities, quick killing efficacy, and a low tendency to induce resistance. AREAS COVERED This review comprehensively summarizes the pharmacological mechanisms of TPI with an emphasis on its antimicrobial and antitumor potential. Furthermore, it presents advances in TPI derivatives and gives a perspective on their future development. The article is based on literature searches using PubMed and SciFinder to retrieve the most up-to-date information of TPI. EXPERT OPINION Bacterial infections and cancer both pose a serious threat to health due to their symbiotic interactions and drug resistance. TPI is anticipated to be a novel agent to control pathogenic bacteria and various tumors through multiple mechanisms of action. Indeed, the continuous advancements in chemical modification and innovative applications of TPI give hope for future improvements in therapeutic efficacy.
Collapse
Affiliation(s)
- Shengxin Lu
- Shanghai Frontiers Science Center for Chinese Medicine Chemical Biology, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Municipality, Shanghai, China
| | - Jiayi Lin
- Shanghai Frontiers Science Center for Chinese Medicine Chemical Biology, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Municipality, Shanghai, China
| | - Jinmei Jin
- Shanghai Frontiers Science Center for Chinese Medicine Chemical Biology, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Municipality, Shanghai, China
| | - Lijun Zhang
- Shanghai Frontiers Science Center for Chinese Medicine Chemical Biology, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Municipality, Shanghai, China
| | - Yingyun Guan
- Department of Pharmacy, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Municipality, Shanghai, China
| | - Hongzhuan Chen
- Shanghai Frontiers Science Center for Chinese Medicine Chemical Biology, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Municipality, Shanghai, China
| | - Ye Wu
- Shanghai Frontiers Science Center for Chinese Medicine Chemical Biology, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Municipality, Shanghai, China
| | - Weidong Zhang
- Shanghai Frontiers Science Center for Chinese Medicine Chemical Biology, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Municipality, Shanghai, China.,School of Pharmacy, Naval Medical University, Municipality, Shanghai, China
| | - Xin Luan
- Shanghai Frontiers Science Center for Chinese Medicine Chemical Biology, Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Municipality, Shanghai, China
| |
Collapse
|
2
|
Cameron AJ, Varnava KG, Edwards PJB, Harjes E, Sarojini V. Acyclic peptides incorporating the d-Phe-2-Abz turn motif: Investigations on antimicrobial activity and propensity to adopt β-hairpin conformations. J Pept Sci 2018; 24:e3094. [PMID: 29900628 DOI: 10.1002/psc.3094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 05/08/2018] [Accepted: 05/16/2018] [Indexed: 02/01/2023]
Abstract
Three linear peptides incorporating d-Phe-2-Abz as the turn motif are reported. Peptide 1, a hydrophobic β-hairpin, served as a proof of principle for the design strategy with both NMR and CD spectra strongly suggesting a β-hairpin conformation. Peptides 2 and 3, designed as amphipathic antimicrobials, exhibited broad spectrum antimicrobial activity, with potency in the nanomolar range against Staphylococcus aureus. Both compounds possess a high degree of selectivity, proving non-haemolytic at concentrations 500 to 800 times higher than their respective minimal inhibitory concentrations (MICs) against S. aureus. Peptide 2 induced cell membrane and cell wall disintegration in both S. aureus and Pseudomonas aeruginosa as observed by transmission electron microscopy. Peptide 2 also demonstrated moderate antifungal activity against Candida albicans with an MIC of 50 μM. Synergism was observed with sub-MIC levels of amphotericin B (AmB), leading to nanomolar MICs against C. albicans for peptide 2. Based on circular dichroism spectra, both peptides 2 and 3 appear to exist as a mixture of conformers with the β-hairpin as a minor conformer in aqueous solution, and a slight increase in hairpin population in 50% trifluoroethanol, which was more pronounced for peptide 3. NMR spectra of peptide 2 in a 1:1 CD3 CN/H2 O mixture and 30 mM deuterated sodium dodecyl sulfate showed evidence of an extended backbone conformation of the β-strand residues. However, inter-strand rotating frame Overhauser effects (ROE) could not be detected and a loosely defined divergent hairpin structure resulted from ROE structure calculation in CD3 CN/H2 O. The loosely defined hairpin conformation is most likely a result of the electrostatic repulsions between cationic strand residues which also probably contribute towards maintaining low haemolytic activity.
Collapse
Affiliation(s)
- Alan J Cameron
- School of Chemical Sciences, The University of Auckland, Auckland, 1142, New Zealand
| | - Kyriakos G Varnava
- School of Chemical Sciences, The University of Auckland, Auckland, 1142, New Zealand
| | - Patrick J B Edwards
- Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand
| | - Elena Harjes
- Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand
| | | |
Collapse
|
3
|
Liu C, Qi J, Shan B, Ma Y. Tachyplesin Causes Membrane Instability That Kills Multidrug-Resistant Bacteria by Inhibiting the 3-Ketoacyl Carrier Protein Reductase FabG. Front Microbiol 2018; 9:825. [PMID: 29765362 PMCID: PMC5938390 DOI: 10.3389/fmicb.2018.00825] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 04/11/2018] [Indexed: 12/19/2022] Open
Abstract
Tachyplesin is a type of cationic β-hairpin antimicrobial peptide discovered in horseshoe crab approximately 30 years ago that is well known for both its potential antimicrobial activities against multidrug-resistant bacteria and its cytotoxicity to mammalian cells. Though its physical interactions with artificial membranes have been well studied, details of its physiological mechanism of action the physiological consequences of its action remain limited. By using the DNA-binding fluorescent dye propidium iodide to monitor membrane integrity, confocal microscopy to assess the intracellular location of FITC-tagged tachyplesin, and RNA sequencing of the differentially expressed genes in four Gram-negative bacteria (Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa) treated with lethal or sublethal concentrations of tachyplesin, we found that compared with levofloxacin-treated bacteria, tachyplesin-treated bacteria showed significant effects on the pathways underlying unsaturated fatty acid biosynthesis. Notably, RNA levels of the conserved and essential 3-ketoacyl carrier protein reductase in this pathway (gene FabG) were elevated in all of the four bacteria after tachyplesin treatment. In vitro tests including surface plasmon resonance and enzyme activity assays showed that tachyplesin could bind and inhibit 3-ketoacyl carrier protein reductase, which was consistent with molecular docking prediction results. As unsaturated fatty acids are important for membrane fluidity, our results provided one possible mechanism to explain how tachyplesin kills bacteria and causes cytotoxicity by targeting membranes, which may be helpful for designing more specific and safer antibiotics based on the function of tachyplesin.
Collapse
Affiliation(s)
- Cunbao Liu
- Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Jialong Qi
- Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Bin Shan
- Department of Clinical Laboratory, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Yanbing Ma
- Laboratory of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| |
Collapse
|
4
|
Manzo G, Serra I, Pira A, Pintus M, Ceccarelli M, Casu M, Rinaldi AC, Scorciapino MA. The singular behavior of a β-type semi-synthetic two branched polypeptide: three-dimensional structure and mode of action. Phys Chem Chem Phys 2018; 18:30998-31011. [PMID: 27805179 DOI: 10.1039/c6cp05464a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Dendrimeric peptides make a versatile group of bioactive peptidomimetics and a potential new class of antimicrobial agents to tackle the pressing threat of multi-drug resistant pathogens. These are branched supramolecular assemblies where multiple copies of the bioactive unit are linked to a central core. Beyond their antimicrobial activity, dendrimeric peptides could also be designed to functionalize the surface of nanoparticles or materials for other medical uses. Despite these properties, however, little is known about the structure-function relationship of such compounds, which is key to unveil the fundamental physico-chemical parameters and design analogues with desired attributes. To close this gap, we focused on a semi-synthetic, two-branched peptide, SB056, endowed with remarkable activity against both Gram-positive and Gram-negative bacteria and limited cytotoxicity. SB056 can be considered the smallest prototypical dendrimeric peptide, with the core restricted to a single lysine residue and only two copies of the same highly cationic 10-mer polypeptide; an octanamide tail is present at the C-terminus. Combining NMR and Molecular Dynamics simulations, we have determined the 3D structure of two analogues. Fluorescence spectroscopy was applied to investigate the water-bilayer partition in the presence of vesicles of variable charge. Vesicle leakage assays were also performed and the experimental data were analyzed by applying an iterative Monte Carlo scheme to estimate the minimum number of bound peptides needed to achieve the release. We unveiled a singular beta hairpin-type structure determined by the peptide chains only, with the octanamide tail available for further functionalization to add new potential properties without affecting the structure.
Collapse
Affiliation(s)
- Giorgia Manzo
- Department of Biomedical Sciences - Biochemistry Unit, University of Cagliari, Monserrato, CA, Italy.
| | - Ilaria Serra
- Department of Chemical and Geological Sciences, University of Cagliari, Monserrato, CA, Italy
| | - Alessandro Pira
- Department of Chemical and Geological Sciences, University of Cagliari, Monserrato, CA, Italy
| | - Manuela Pintus
- Department of Biomedical Sciences - Biochemistry Unit, University of Cagliari, Monserrato, CA, Italy.
| | - Matteo Ceccarelli
- Department of Physics, University of Cagliari, Monserrato, CA, Italy
| | - Mariano Casu
- Department of Physics, University of Cagliari, Monserrato, CA, Italy
| | - Andrea C Rinaldi
- Department of Biomedical Sciences - Biochemistry Unit, University of Cagliari, Monserrato, CA, Italy.
| | | |
Collapse
|
5
|
Edwards IA, Elliott AG, Kavanagh AM, Zuegg J, Blaskovich MAT, Cooper MA. Contribution of Amphipathicity and Hydrophobicity to the Antimicrobial Activity and Cytotoxicity of β-Hairpin Peptides. ACS Infect Dis 2016; 2:442-450. [PMID: 27331141 PMCID: PMC4906375 DOI: 10.1021/acsinfecdis.6b00045] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Indexed: 12/12/2022]
Abstract
![]()
Bacteria have acquired
extensive resistance mechanisms to protect themselves against antibiotic
action. Today the bacterial membrane has become one of the “final
frontiers” in the search for new compounds acting on novel
targets to address the threat of multi-drug resistant (MDR) and XDR
bacterial pathogens. β-Hairpin antimicrobial peptides are amphipathic,
membrane-binding antibiotics that exhibit a broad range of activities
against Gram-positive, Gram-negative, and fungal pathogens. However,
most members of the class also possess adverse cytotoxicity and hemolytic
activity that preclude their development as candidate antimicrobials.
We examined peptide hydrophobicity, amphipathicity, and structure
to better dissect and understand the correlation between antimicrobial
activity and toxicity, membrane binding, and membrane permeability.
The hydrophobicity, pI, net charge at physiological
pH, and amphipathic moment for the β-hairpin antimicrobial peptides
tachyplesin-1, polyphemusin-1, protegrin-1, gomesin, arenicin-3, and
thanatin were determined and correlated with key antimicrobial activity
and toxicity data. These included antimicrobial activity against five
key bacterial pathogens and two fungi, cytotoxicity against human
cell lines, and hemolytic activity in human erythrocytes. Observed
antimicrobial activity trends correlated with compound amphipathicity
and, to a lesser extent, with overall hydrophobicity. Antimicrobial
activity increased with amphipathicity, but unfortunately so did toxicity.
Of note, tachyplesin-1 was found to be 8-fold more amphipathic than
gomesin. These analyses identify tachyplesin-1 as a promising scaffold
for rational design and synthetic optimization toward an antibiotic
candidate.
Collapse
Affiliation(s)
- Ingrid A. Edwards
- Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road (Building 80), Brisbane, Queensland 4072, Australia
| | - Alysha G. Elliott
- Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road (Building 80), Brisbane, Queensland 4072, Australia
| | - Angela M. Kavanagh
- Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road (Building 80), Brisbane, Queensland 4072, Australia
| | - Johannes Zuegg
- Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road (Building 80), Brisbane, Queensland 4072, Australia
| | - Mark A. T. Blaskovich
- Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road (Building 80), Brisbane, Queensland 4072, Australia
| | - Matthew A. Cooper
- Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road (Building 80), Brisbane, Queensland 4072, Australia
| |
Collapse
|
6
|
Han E, Lee H. Structural effects of tachyplesin I and its linear derivative on their aggregation and mobility in lipid bilayers. J Mol Graph Model 2015; 59:123-8. [DOI: 10.1016/j.jmgm.2015.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/09/2015] [Accepted: 04/17/2015] [Indexed: 10/23/2022]
|
7
|
Kier BL, Anderson JM, Andersen NH. Disulfide-Mediated β-Strand Dimers: Hyperstable β-Sheets Lacking Tertiary Interactions and Turns. J Am Chem Soc 2015; 137:5363-71. [PMID: 25835058 PMCID: PMC7450586 DOI: 10.1021/ja5117809] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Disulfide bonds between cysteine residues are essential to the structure and folding of many proteins. Yet their role in the design of structured peptides and proteins has frequently been limited to use as intrachain covalent staples that reinforce existing structure or induce knot-like conformations. In β-hairpins, their placement at non-H-bonding positions across antiparallel strands has proven useful for achieving fully folded positive controls. Here we report a new class of designed β-sheet peptide dimers with strand-central disulfides as a key element. We have found that the mere presence of a disulfide bond near the middle of a short peptide chain is sufficient to nucleate some antiparallel β-sheet structure; addition of β-capping units and other favorable cross-strand interactions yield hyperstable sheets. Strand-central cystines were found to be superior to the best designed reversing turns in terms of nucleating β-sheet structure formation. We have explored the limitations and possibilities of this technique (the use of disulfides as sheet nucleators), and we provide a set of rules and rationales for the application and further design of disulfide-tethered "turnless" β-sheets.
Collapse
Affiliation(s)
- Brandon L Kier
- Chemistry Department, University of Washington, Seattle, Washington 98195, United States
| | - Jordan M Anderson
- Chemistry Department, University of Washington, Seattle, Washington 98195, United States
| | - Niels H Andersen
- Chemistry Department, University of Washington, Seattle, Washington 98195, United States
| |
Collapse
|
8
|
Yan ECY, Wang Z, Fu L. Proteins at Interfaces Probed by Chiral Vibrational Sum Frequency Generation Spectroscopy. J Phys Chem B 2015; 119:2769-85. [DOI: 10.1021/jp508926e] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Elsa C. Y. Yan
- Department of Chemistry, Yale University, New Haven, CT 06511, United States
| | - Zhuguang Wang
- Department of Chemistry, Yale University, New Haven, CT 06511, United States
| | - Li Fu
- Department of Chemistry, Yale University, New Haven, CT 06511, United States
| |
Collapse
|
9
|
Boumaiza M, Ezzine A, Jaouen M, Sari MA, Marzouki MN. Molecular characterization of a novel hepcidin (HepcD) from Camelus dromedarius. Synthetic peptide forms exhibit antibacterial activity. J Pept Sci 2014; 20:680-8. [PMID: 24895313 DOI: 10.1002/psc.2644] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/27/2014] [Accepted: 04/01/2014] [Indexed: 01/15/2023]
Abstract
Hepcidin is a cysteine-rich peptide widely characterized in immunological processes and antimicrobial activity in several vertebrate species. Obviously, this hormone plays a central role in the regulation of systemic iron homeostasis. However, its role in camelids' immune response and whether it is involved in antibacterial immunity have not yet been proven. In this study, we characterized the Arabian camel hepcidin nucleotide sequence with an open reading frame of 252 bp encoding an 83-amino acid preprohepcidin peptide. Eight cysteine key residues conserved in all mammalian hepcidin sequences were identified. The model structure analysis of hepcidin-25 peptide showed a high homology structure and sequence identity to the human hepcidin. Two different hepcidin-25 analogs manually synthesized by SPPS shared significant cytotoxic capacity toward the Gram-negative bacterium Escherichia coli American Type Culture Collection (ATCC) 8739 as well as the Gram-positive bacteria Bacillus subtilis ATCC 11779 and Staphylococcus aureus ATCC 6538 in vitro. The three disulfide bridges hepcidin analog demonstrated bactericidal activity, against B. subtilis ATCC 11779 and S. aureus ATCC 6538 strains, at the concentration of 15 μM (50 µg/ml) or above at pH 6.2. This result correlates with the revealed structural features suggesting that camel hepcidin is proposed to be involved in antibacterial process of innate immune response.
Collapse
Affiliation(s)
- Mohamed Boumaiza
- Laboratoire d'ingénierie des protéines et des molécules bioactives, Institut National des Sciences Appliquées et de Technologie, Université de Carthage, BP 676, 1080, Tunis Cedex, Tunisia
| | | | | | | | | |
Collapse
|
10
|
Fu L, Wang Z, Yan EC. Chiral vibrational structures of proteins at interfaces probed by sum frequency generation spectroscopy. Int J Mol Sci 2011; 12:9404-25. [PMID: 22272140 PMCID: PMC3257137 DOI: 10.3390/ijms12129404] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 12/13/2011] [Accepted: 12/13/2011] [Indexed: 12/04/2022] Open
Abstract
We review the recent development of chiral sum frequency generation (SFG) spectroscopy and its applications to study chiral vibrational structures at interfaces. This review summarizes observations of chiral SFG signals from various molecular systems and describes the molecular origins of chiral SFG response. It focuses on the chiral vibrational structures of proteins and presents the chiral SFG spectra of proteins at interfaces in the C-H stretch, amide I, and N-H stretch regions. In particular, a combination of chiral amide I and N-H stretches of the peptide backbone provides highly characteristic vibrational signatures, unique to various secondary structures, which demonstrate the capacity of chiral SFG spectroscopy to distinguish protein secondary structures at interfaces. On the basis of these recent developments, we further discuss the advantages of chiral SFG spectroscopy and its potential application in various fields of science and technology. We conclude that chiral SFG spectroscopy can be a new approach to probe chiral vibrational structures of protein at interfaces, providing structural and dynamic information to study in situ and in real time protein structures and dynamics at interfaces.
Collapse
Affiliation(s)
- Li Fu
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT, 06520, USA; E-Mails: (L.F.); (Z.W.)
| | - Zhuguang Wang
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT, 06520, USA; E-Mails: (L.F.); (Z.W.)
| | - Elsa C.Y. Yan
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT, 06520, USA; E-Mails: (L.F.); (Z.W.)
| |
Collapse
|
11
|
Boughton AP, Nguyen K, Andricioaei I, Chen Z. Interfacial orientation and secondary structure change in tachyplesin I: molecular dynamics and sum frequency generation spectroscopy studies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:14343-14351. [PMID: 22054114 PMCID: PMC3235698 DOI: 10.1021/la203192c] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent advances in the collection and interpretation of surface-sensitive vibrational spectroscopic measurements have made it possible to study the orientation of peptides and proteins in situ in a biologically relevant environment. However, interpretation of sum frequency generation (SFG) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) vibrational spectroscopy is hindered by the fact that orientation cannot be inferred without some prior knowledge of the protein structure. In this work, molecular dynamics simulations were used to study the interfacial orientation and structural deformation of the short β-sheet peptide tachyplesin I at the polystyrene/water interface. By combining these results with ATR-FTIR and SFG measurements, reasonable agreement was found with the simulation results, suggesting that tachyplesin I lies parallel to the surface, although the simulation results imply a broader distribution of peptide twist angles than could be characterized using available experimental measurements. The interfacial structure was found to be deformable even when disulfide bonds were preserved, and these local deviations from a purely extended β-sheet conformation may be of importance to future developments in the interpretation of SFG and ATR-FTIR spectra.
Collapse
Affiliation(s)
- Andrew P. Boughton
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109 USA
| | - Khoi Nguyen
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109 USA
- Department of Applied Chemistry, School of Biotechnology, International University- Vietnam National University, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 70000 Vietnam
| | - Ioan Andricioaei
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences 2, Irvine, CA 92697 USA
| | - Zhan Chen
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109 USA
| |
Collapse
|
12
|
Ye S, Nguyen KT, Le Clair SV, Chen Z. In situ molecular level studies on membrane related peptides and proteins in real time using sum frequency generation vibrational spectroscopy. J Struct Biol 2009; 168:61-77. [PMID: 19306928 PMCID: PMC2753614 DOI: 10.1016/j.jsb.2009.03.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 03/11/2009] [Accepted: 03/13/2009] [Indexed: 12/11/2022]
Abstract
Sum frequency generation (SFG) vibrational spectroscopy has been demonstrated to be a powerful technique to study the molecular structures of surfaces and interfaces in different chemical environments. This review summarizes recent SFG studies on hybrid bilayer membranes and substrate-supported lipid monolayers and bilayers, the interaction between peptides/proteins and lipid monolayers/bilayers, and bilayer perturbation induced by peptides/proteins. To demonstrate the ability of SFG to determine the orientations of various secondary structures, studies on the interactions between different peptides/proteins (melittin, G proteins, alamethicin, and tachyplesin I) and lipid bilayers are discussed. Molecular level details revealed by SFG in these studies show that SFG can provide a unique understanding on the interactions between a lipid monolayer/bilayer and peptides/proteins in real time, in situ and without any exogenous labeling.
Collapse
Affiliation(s)
- Shuji Ye
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - Khoi Tan Nguyen
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
| | | | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
| |
Collapse
|
13
|
Yokoyama S, Iida Y, Kawasaki Y, Minami Y, Watanabe K, Yagi F. The chitin-binding capability of Cy-AMP1 from cycad is essential to antifungal activity. J Pept Sci 2009; 15:492-7. [PMID: 19466694 DOI: 10.1002/psc.1147] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Antimicrobial peptides are important components of the host innate immune responses by exerting broad-spectrum microbicidal activity against pathogenic microbes. Cy-AMP1 found in the cycad (Cycas revoluta) seeds has chitin-binding ability, and the chitin-binding domain was conserved in knottin-type and hevein-type antimicrobial peptides. The recombinant Cy-AMP1 was expressed in Escherichia coli and purified to study the role of chitin-binding domain. The mutants of Cy-AMP1 lost chitin-binding ability completely, and its antifungal activity was markedly decreased in comparison with native Cy-AMP1. However, the antimicrobial activities of the mutant peptides are nearly identical to that of native one. It was suggested that the chitin-binding domain plays an essential role in antifungal, but not antimicrobial, activity of Cy-AMP1.
Collapse
Affiliation(s)
- Seiya Yokoyama
- Department of Applied Biological Chemistry, The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24, Korimoto, Kagoshima, 890-0065, Japan
| | | | | | | | | | | |
Collapse
|
14
|
Rathinakumar R, Walkenhorst WF, Wimley WC. Broad-spectrum antimicrobial peptides by rational combinatorial design and high-throughput screening: the importance of interfacial activity. J Am Chem Soc 2009; 131:7609-17. [PMID: 19445503 PMCID: PMC2935846 DOI: 10.1021/ja8093247] [Citation(s) in RCA: 237] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We recently described 10 peptides selected from a 16,384-member combinatorial library based on their ability to permeabilize synthetic lipid vesicles in vitro. These peptides did not share a common sequence motif, length, or net charge; nonetheless, they shared a mechanism of action that is similar to the natural membrane permeabilizing antimicrobial peptides (AMP). To characterize the selected peptides and to compare the activity of AMPs in vivo and in vitro, we report on the biological activity of the same selected peptides in bacteria, fungi, and mammalian cells. Each of the peptides has sterilizing activity against all classes of microbes tested, at 2-8 microM peptide, with only slight hemolytic or cytotoxicity against mammalian cells. Similar to many natural AMPs, bacteria are killed within a few minutes of peptide addition, and the lethal step in vivo is membrane permeabilization. Single D-amino acid substitutions eliminated or diminished the secondary structure of the peptides, and yet, they retained activity against some microbes. Thus, secondary structure and biological activity are not coupled, consistent with the hypothesis that AMPs do not form pores of well-defined structure in membranes but rather destabilize membranes by partitioning into membrane interfaces and disturbing the organization of the lipids, a property that we have called "interfacial activity". The observation that broad-spectrum activity, but not all antimicrobial activity, is lost by small changes to the peptides suggests that the in vitro screen is specifically selecting for the rare peptides that have broad-spectrum activity. We put forth the hypothesis that methods focusing on screening peptide libraries in vitro for members with the appropriate interfacial activity can enable the design, selection, and discovery of novel, potent, and broad-spectrum membrane-active antibiotics.
Collapse
Affiliation(s)
- Ramesh Rathinakumar
- Department of Biochemistry, Tulane University Health Sciences Center, New Orleans LA, 70112
| | | | - William C. Wimley
- Department of Biochemistry, Tulane University Health Sciences Center, New Orleans LA, 70112
| |
Collapse
|
15
|
Udugamasooriya DG, Spaller MR. Conformational constraint in protein ligand design and the inconsistency of binding entropy. Biopolymers 2008; 89:653-67. [DOI: 10.1002/bip.20983] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
16
|
Mena NP, Esparza A, Tapia V, Valdés P, Núñez MT. Hepcidin inhibits apical iron uptake in intestinal cells. Am J Physiol Gastrointest Liver Physiol 2008; 294:G192-8. [PMID: 17962361 DOI: 10.1152/ajpgi.00122.2007] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hepcidin (Hepc) is considered a key mediator in iron trafficking. Although the mechanism of Hepc action in macrophages is fairly well established, much less is known about its action in intestinal cells, one of the main targets of Hepc. The current study investigated the effects of physiologically generated Hepc on iron transport in Caco-2 cell monolayers and rat duodenal segments compared with the effects on the J774 macrophage cell line. Addition of Hepc to Caco-2 cells or rat duodenal segments strongly inhibited apical (55)Fe uptake without apparent effects on the transfer of (55)Fe from the cells to the basolateral medium. Concurrently, the levels of divalent metal transporter 1 (DMT1) mRNA and protein in Caco-2 cells decreased while the mRNA and protein levels of the iron export transporter ferroportin did not change. Plasma membrane localization of ferroportin was studied by selective biotinylation of apical and basolateral membrane domains; Hepc induced rapid internalization of ferroportin in J774 cells but not in Caco-2 cells These results indicate that the effect of Hepc is cell dependent: in macrophages it inhibits iron export by inducing ferroportin degradation, whereas in enterocytes it inhibits apical iron uptake by inhibiting DMT1 transcription. Our results highlight the crucial role of Hepc in the control of intestinal iron absorption.
Collapse
Affiliation(s)
- Natalia P Mena
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
| | | | | | | | | |
Collapse
|
17
|
Hong M. Structure, topology, and dynamics of membrane peptides and proteins from solid-state NMR spectroscopy. J Phys Chem B 2007; 111:10340-51. [PMID: 17685648 DOI: 10.1021/jp073652j] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The high-resolution structure of membrane proteins is notoriously difficult to determine due to the hydrophobic nature of the protein-membrane complexes. Solid-state NMR spectroscopy is a unique and powerful atomic-resolution probe of the structure and dynamics of these important biological molecules. A number of new solid-state NMR methods for determining the depth of insertion, orientation, oligomeric structure, and long-range (10-15 A) distances of membrane proteins are summarized. Membrane protein depths can now be determined using several complementary techniques with varying site-specificity, distance precision, and mobility requirement on the protein. Membrane protein orientation can now be determined with or without macroscopic alignment, the latter providing a novel alternative for orientation determination of intrinsically curvature-inducing proteins. The novel analyses of beta-sheet membrane protein orientation are described. The quaternary structure of membrane peptide assemblies can now be elucidated using a 19F spin diffusion technique that simultaneously yields the oligomeric number and intermolecular distances up to 15 A. Finally, long-range distances up to approximately 10 A can now be measured using 1H spins with an accuracy of better than 1 A. These methods are demonstrated on several beta-sheet membrane peptides with antimicrobial activities and on two alpha-helical ion-channel proteins. Finally, we show that the nearly ubiquitous dynamics of membrane proteins can be readily examined using 2D correlation experiments. An intimate appreciation of molecular motion in these systems not only leads to important insights into the specific function of these membrane proteins but also may be exploited for other purposes such as orientation determination.
Collapse
Affiliation(s)
- Mei Hong
- Department of Chemistry, Iowa State University, Ames, Iowa, USA.
| |
Collapse
|
18
|
Nair D, Fry B, Alewood P, Kumar P, Kini R. Antimicrobial activity of omwaprin, a new member of the waprin family of snake venom proteins. Biochem J 2007; 402:93-104. [PMID: 17044815 PMCID: PMC1783991 DOI: 10.1042/bj20060318] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have isolated and characterized omwaprin, a 50-amino-acid cationic protein from the venom of inland taipan (Oxyuranus microlepidotus). It is a new member of the waprin family of snake venom proteins. A synthetic gene was designed and constructed for expressing the recombinant protein in Escherichia coli. Recombinant omwaprin was used for carrying out functional analyses. The protein is non-toxic to Swiss albino mice at doses of up to 10 mg/kg when administered intraperitoneally. However, it shows selective and dose-dependant antibacterial activity against Gram-positive bacteria. The minimum inhibitory doses were in the range 2-10 microg for selected species of bacteria in radial diffusion assays. The antibacterial activity is salt-tolerant up to 350 mM NaCl. However, omwaprin lost its antibacterial activity upon reduction and alkylation of its cysteine residues, or upon deletion of six N-terminal amino acid residues, four of which are positively charged. These observations indicate that the three-dimensional structure constrained by four disulfide bonds and the N-terminal residues are essential for its activity. The mechanism of action is via membrane disruption, as shown by scanning electron microscopy. Importantly, omwaprin lacks haemolytic activity on human erythrocytes. This demonstrates the specificity of omwaprin for bacterial membranes. Unlike other reported WAP (whey acidic protein) domain-containing antibacterial proteins, including elafin, EPPIN (epididymal proteinase inhibitor), SWAM1 and SWAM2 [single WAP (whey acidic protein) motif proteins 1 and 2] and SLPI (secretory leucocyte proteinase inhibitor), omwaprin shows species-specific activity on the Gram-positive bacteria tested.
Collapse
Affiliation(s)
- Dileep G. Nair
- *Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543
| | - Bryan G. Fry
- *Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543
- †Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia 4072
| | - Paul Alewood
- †Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia 4072
| | - Prakash P. Kumar
- *Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543
- ‡Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604
- Correspondence may be addressed to either of these authors (email or )
| | - R. Manjunatha Kini
- *Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543
- §Department of Biochemistry and Molecular Biophysics, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, U.S.A
- Correspondence may be addressed to either of these authors (email or )
| |
Collapse
|
19
|
Chen X, Chen Z. SFG studies on interactions between antimicrobial peptides and supported lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1257-73. [PMID: 16524559 DOI: 10.1016/j.bbamem.2006.01.017] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/11/2006] [Accepted: 01/24/2006] [Indexed: 11/29/2022]
Abstract
The mode of action of antimicrobial peptides (AMPs) in disrupting cell membrane bilayers is of fundamental importance in understanding the efficiency of different AMPs, which is crucial to design antibiotics with improved properties. Recent developments in the field of sum frequency generation (SFG) vibrational spectroscopy have made it a powerful and unique biophysical technique in investigating the interactions between AMPs and a single substrate supported planar lipid bilayer. We will review some of the recent progress in applying SFG to study membrane lipid bilayers and discuss how SFG can provide novel information such as real-time bilayer structure change and AMP orientation during AMP-lipid bilayer interactions in a very biologically relevant manner. Several examples of applying SFG to monitor such interactions between AMPs and a dipalmitoyl phosphatidylglycerol (DPPG) bilayer are presented. Different modes of actions are observed for melittin, tachyplesin I, d-magainin 2, MSI-843, and a synthetic antibacterial oligomer, demonstrating that SFG is very effective in the study of AMPs and AMP-lipid bilayer interactions.
Collapse
Affiliation(s)
- Xiaoyun Chen
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | | |
Collapse
|
20
|
Ramamoorthy A, Thennarasu S, Tan A, Gottipati K, Sreekumar S, Heyl DL, An FYP, Shelburne CE. Deletion of all cysteines in tachyplesin I abolishes hemolytic activity and retains antimicrobial activity and lipopolysaccharide selective binding. Biochemistry 2006; 45:6529-40. [PMID: 16700563 PMCID: PMC2515376 DOI: 10.1021/bi052629q] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tachyplesin I is a cyclic beta-sheet antimicrobial peptide isolated from the hemocytes of Tachypleus tridentatus. The four cysteine residues in tachyplesin I play a structural role in imparting amphipathicity to the peptide which has been shown to be essential for its activity. We investigated the role of amphipathicity using an analogue of tachyplesin I (TP-I), CDT (KWFRVYRGIYRRR-NH(2)), in which all four cysteines were deleted. Like TP-I, CDT shows antimicrobial activity and disrupts Escherichia coli outer membrane and model membranes mimicking bacterial inner membranes at micromolar concentrations. The CDT peptide does not cause hemolysis up to 200 microg/mL while TP-I showed about 10% hemolysis at 100 microg/mL and about 25% hemolysis at 150 microg/mL. Peptide-into-lipid titrations under isothermal conditions reveal that the interaction of CDT with lipid membranes is an enthalpy-driven process. Binding assays performed using fluorometry demonstrate that the peptide CDT binds and inserts into only negatively charged membranes. The peptide-induced thermotropic phase transition of MLVs formed of DMPC and the DMPC/DMPG (7:3) mixture suggests specific lipid-peptide interactions. The circular dichroism study shows that the peptide exists as an unordered structure in an aqueous buffer and adopts a more ordered beta-structure upon binding to negatively charged membrane. The NMR data suggest that CDT binding to negatively charged bilayers induces a change in the lipid headgroup conformation with the lipid headgroup moving out of the bilayer surface toward the water phase, and therefore, a barrel stave mechanism of membrane disruption is unlikely as the peptide is located near the headgroup region of lipids. The lamellar phase (31)P chemical shift spectra observed at various concentrations of the peptide in bilayers suggest that the peptide may function neither via fragmentation of bilayers nor by promoting nonlamellar structures. NMR and fluorescence data suggest that the presence of cholesterol inhibits the peptide binding to the bilayers. These properties help to explain that cysteine residues may not contribute to antimicrobial activity and that the loss of hemolytic activity is due to lack of hydrophobicity and amphipathicity.
Collapse
Affiliation(s)
- Ayyalusamy Ramamoorthy
- Department of Chemistry and Biophysics Research Division, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Doherty T, Waring AJ, Hong M. Peptide-lipid interactions of the beta-hairpin antimicrobial peptide tachyplesin and its linear derivatives from solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1285-91. [PMID: 16678119 DOI: 10.1016/j.bbamem.2006.03.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 03/13/2006] [Accepted: 03/14/2006] [Indexed: 10/24/2022]
Abstract
The peptide-lipid interaction of a beta-hairpin antimicrobial peptide tachyplesin-1 (TP-1) and its linear derivatives are investigated to gain insight into the mechanism of antimicrobial activity. (31)P and (2)H NMR spectra of uniaxially aligned lipid bilayers of varying compositions and peptide concentrations are measured to determine the peptide-induced orientational disorder and the selectivity of membrane disruption by tachyplesin. The disulfide-linked TP-1 does not cause any disorder to the neutral POPC and POPC/cholesterol membranes but induces both micellization and random orientation distribution to the anionic POPE/POPG membranes above a peptide concentration of 2%. In comparison, the anionic POPC/POPG bilayer is completely unaffected by TP-1 binding, suggesting that TP-1 induces negative curvature strain to the membrane as a mechanism of its action. Removal of the disulfide bonds by substitution of Cys residues with Tyr and Ala abolishes the micellization of POPE/POPG bilayers but retains the orientation randomization of both POPC/POPG and POPE/POPG bilayers. Thus, linear tachyplesin derivatives have membrane disruptive abilities but use different mechanisms from the wild-type peptide. The different lipid-peptide interactions between TP-1 and other beta-hairpin antimicrobial peptides are discussed in terms of their molecular structure.
Collapse
Affiliation(s)
- Timothy Doherty
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
| | | | | |
Collapse
|
22
|
Yenugu S, Hamil KG, French FS, Hall SH. Antimicrobial Actions of Human and Macaque Sperm Associated Antigen (SPAG) 11 Isoforms: influence of the N-terminal peptide. Mol Cell Biochem 2006; 284:25-37. [PMID: 16411022 DOI: 10.1007/s11010-005-9009-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Accepted: 09/15/2005] [Indexed: 11/30/2022]
Abstract
In addition to their role in sperm maturation, recent evidence has indicated that epididymal proteins have a role in male reproductive tract innate immunity. Herein we demonstrate that human and macaque epididymal protein isoforms in the SPAG (sperm associated antigen) 11 family, full length SPAG11C, K and L exhibit potent antibacterial activity against E. coli. Analysis of activities of the N- and C-terminal domains revealed that the human N-terminal peptide is bactericidal, while the C-terminal domains that contain the defensin-like 6 cysteine array in SPAG11C and partial arrays in SPAG11K and SPAG11L, lack antibacterial activity. The N-terminal peptide does not appear to contain all the determinants of activity since full-length human SPAG11C is more active than the isolated N-terminal peptide and since sulfhydryl reduction and alkylation, which would affect primarily the C-terminal peptides, completely abolished activities of the whole proteins. These results suggest that the structure conferred by the disulfide bonds in human SPAG11C contributes to the antibacterial activity of the whole molecule. The activities of the N-terminal peptide and of full length human SPAG11C were somewhat reduced in increasing NaCl concentrations. In contrast, the antibacterial activities of full length macaque SPAG11C, K and L were unaffected by the presence of NaCl suggesting a mechanism in the macaque that is less dependent upon electrostatic interactions. SPAG11C, K and L disrupted E. coli membranes but had no effect on erythrocyte membranes. Inhibition of E. coli RNA, DNA and protein synthesis by nonlethal concentrations of SPAG11 isoforms indicated an additional mechanism of bacterial killing.
Collapse
Affiliation(s)
- Suresh Yenugu
- Laboratories for Reproductive Biology, Department of Pediatrics, University of North Carolina, Chapel Hill, 27599-7500, USA
| | | | | | | |
Collapse
|
23
|
Abstract
Antimicrobial peptides (AMPs) have been isolated and characterized from tissues and organisms representing virtually every kingdom and phylum. Their amino acid composition, amphipathicity, cationic charge, and size allow them to attach to and insert into membrane bilayers to form pores by 'barrel-stave', 'carpet' or 'toroidal-pore' mechanisms. Although these models are helpful for defining mechanisms of AMP activity, their relevance to resolving how peptides damage and kill microorganisms still needs to be clarified. Moreover, many AMPs employ sophisticated and dynamic mechanisms of action to carry out their likely roles in antimicrobial host defense. Recently, it has been speculated that transmembrane pore formation is not the only mechanism of microbial killing by AMPs. In fact, several observations suggest that translocated AMPs can alter cytoplasmic membrane septum formation, reduce cell-wall, nucleic acid, and protein synthesis, and inhibit enzymatic activity. In this review, we present the structures of several AMPs as well as models of how AMPs induce pore formation. AMPs have received special attention as a possible alternative way to combat antibiotic-resistant bacterial strains. It may be possible to design synthetic AMPs with enhanced activity for microbial cells, especially those with antibiotic resistance, as well as synergistic effects with conventional antibiotic agents that lack cytotoxic or hemolytic activity.
Collapse
Affiliation(s)
- Yoonkyung Park
- Research Center for Proteineous Materials, Chosun University, Dong-Ku, Kwangju, Korea
| | | |
Collapse
|
24
|
Alewood D, Nielsen K, Alewood PF, Craik DJ, Andrews P, Nerrie M, White S, Domagala T, Walker F, Rothacker J, Burgess AW, Nice EC. The role of disulfide bonds in the structure and function of murine epidermal growth factor (mEGF). Growth Factors 2005; 23:97-110. [PMID: 16019431 DOI: 10.1080/08977190500096061] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A systematic study using solid phase peptide synthesis has been undertaken to examine the role of the disulfide bonds in the structure and function of mEGF. A combination of one, two and three native disulfide pair analogues of an active truncated (4-48) form of mEGF have been synthesised by replacing specific cysteine residues with isosteric a-amino-n-butyric acid (Abu). Oxidation of the peptides was performed using either conventional aerobic oxidation at basic pH, in DMSO under acidic conditions or via selective disulfide formation using orthogonal protection of the cysteine pairs. The contribution of individual, or pairs of, disulfide bonds to EGF structure was evaluated by CD and (1)H-NMR spectroscopy. The mitogenic activity of each analogue was determined using Balb/c 3T3 mouse fibroblastsAs we have reported previously (Barnham et al. 1998), the disulfide bond between residues 6 and 20 can be removed with significant retention of biological activity (EC50 20-50 nM). The overall structure of this analogue was similar to that of native mEGF, indicating that the loss of the 6-20 disulfide bridge did not affect the global fold of the molecule. We now show that removal of any other disulfide bond, either singly or in pairs, results in a major disruption of the tertiary structure, and a large loss of activity (EC50>900 nM). Remarkably, the linear analogue appears to have greater activity (EC50 580 nM) than most one and two disulfide bond analogues although it does not have a definable tertiary structure.
Collapse
Affiliation(s)
- Dianne Alewood
- The Institute for Molecular Bioscience, The University of Queensland, Australia
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Chen X, Wang J, Sniadecki JJ, Even MA, Chen Z. Probing alpha-helical and beta-sheet structures of peptides at solid/liquid interfaces with SFG. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:2662-2664. [PMID: 15779931 DOI: 10.1021/la050048w] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We demonstrated that sum frequency generation (SFG) vibrational spectroscopy can distinguish different secondary structures of proteins or peptides adsorbed at solid/liquid interfaces. The SFG spectrum for tachyplesin I at the polystyrene (PS)/solution interface has a fingerprint peak corresponding to the B1/B3 mode of the antiparallel beta-sheet. This peak disappeared upon the addition of dithiothreitol, which can disrupt the beta-sheet structure. The SFG spectrum indicative of the MSI594 alpha-helical structure was observed at the PS/MSI594 solution interface. This research validates SFG as a powerful technique for revealing detailed secondary structures of interfacial proteins and peptides.
Collapse
Affiliation(s)
- Xiaoyun Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | | | | | | |
Collapse
|
26
|
Yenugu S, Richardson RT, Sivashanmugam P, Wang Z, O'rand MG, French FS, Hall SH. Antimicrobial Activity of Human EPPIN, an Androgen-Regulated, Sperm-Bound Protein with a Whey Acidic Protein Motif1. Biol Reprod 2004; 71:1484-90. [PMID: 15229136 DOI: 10.1095/biolreprod.104.031567] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The role of epididymal sperm-binding proteins in reproductive tract immunity is now well recognized in addition to their role in sperm maturation. Spermatozoa acquire forward motility and fertilizing ability during their passage through the epididymis, where they acquire a wide variety of proteins belonging to different classes. Previously, we demonstrated that EPPIN (epididymal protease inhibitor), an androgen-regulated, sperm-binding protein containing protease-inhibitory motifs, is expressed specifically in the testis and epididymis. In the present study, we investigated the antibacterial activity of EPPIN against Escherichia coli and the mechanism of antimicrobial action. EPPIN exhibited dose- and time-dependent antibacterial activity that was relatively insensitive to salt. However, EPPIN lost its antibacterial activity completely on reduction and alkylation of its cysteines, indicating the importance of disulfide bonds for its activity. EPPIN permeabilized the outer and inner membranes of E. coli, which is consistent with its ability to induce striking morphological alterations of E. coli membranes as shown by scanning electron microscopy. EPPIN did not cause disruption of eukaryotic membranes in the rat erythrocyte hemolytic assay. The present results indicate that EPPIN has a role in the innate immune system of human epididymis.
Collapse
Affiliation(s)
- Suresh Yenugu
- Laboratories for Reproductive Biology, University of North Carolina, Chapel Hill, North Carolina 27599-7500, USA
| | | | | | | | | | | | | |
Collapse
|
27
|
Yenugu S, Hamil KG, Radhakrishnan Y, French FS, Hall SH. The androgen-regulated epididymal sperm-binding protein, human beta-defensin 118 (DEFB118) (formerly ESC42), is an antimicrobial beta-defensin. Endocrinology 2004; 145:3165-73. [PMID: 15033915 DOI: 10.1210/en.2003-1698] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Spermatozoa bind a variety of proteins as they pass through the proximal regions of the epididymis, where they acquire forward motility and fertilizing ability. Recent evidence indicates that certain epididymis-specific secretory proteins that bind sperm have antibacterial activity and may function as part of the innate immune system. We reported earlier that ESC42, now designated human beta-defensin 118 (DEFB118), is a sperm-binding protein. In this study, we demonstrate that DEFB118 has potent antibacterial activity that is dose, time, and structure dependent. Incubation of Escherichia coli for 60 min with 10 microg/ml DEFB118 reduced bacterial survival to 20% of the control, and 25 microg/ml reduced survival to 5% of the control. DEFB118 concentrations of 50 and 100 microg/ml further reduced survival to less than 2 and 1%, respectively. A biphasic effect of salt concentration on the antibacterial activity of DEFB118 was observed. Reduction of disulfide bonds and alkylation of cysteines resulted in the complete loss of antibacterial activity. DEFB118 caused rapid permeabilization of both outer and inner membranes of E. coli and striking morphological alterations in the bacterial surfaces visible by scanning electron microscopy consistent with a membrane-disruptive mechanism of bacterial killing. In contrast, eukaryotic cell membranes were not permeabilized by DEFB118, as indicated by the rat erythrocyte hemolytic assay. Studies on DEFB118 inhibition of macromolecular synthesis and membrane permeability in E. coli were consistent with a primary effect at the cell membrane level. DEFB118 may contribute to epididymal innate immunity and protect the sperm against attack by microorganisms in the male and female reproductive tracts.
Collapse
Affiliation(s)
- Suresh Yenugu
- Laboratories for Reproductive Biology, CB 7500, Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina 27599-7500, USA
| | | | | | | | | |
Collapse
|
28
|
Powers JPS, Hancock REW. The relationship between peptide structure and antibacterial activity. Peptides 2003; 24:1681-91. [PMID: 15019199 DOI: 10.1016/j.peptides.2003.08.023] [Citation(s) in RCA: 642] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Accepted: 08/08/2003] [Indexed: 10/26/2022]
Abstract
Cationic antimicrobial peptides are a class of small, positively charged peptides known for their broad-spectrum antimicrobial activity. These peptides have also been shown to possess anti-viral and anti-cancer activity and, most recently, the ability to modulate the innate immune response. To date, a large number of antimicrobial peptides have been chemically characterized, however, few high-resolution structures are available. Structure-activity studies of these peptides reveal two main requirements for antimicrobial activity, (1) a cationic charge and (2) an induced amphipathic conformation. In addition to peptide conformation, the role of membrane lipid composition, specifically non-bilayer lipids, on peptide activity will also be discussed.
Collapse
Affiliation(s)
- Jon-Paul S Powers
- Department of Microbiology and Immunology, University of British Columbia, #300-6174 University Boulevard, Vancouver, BC, Canada V6T 1Z3.
| | | |
Collapse
|
29
|
Yenugu S, Hamil KG, Birse CE, Ruben SM, French FS, Hall SH. Antibacterial properties of the sperm-binding proteins and peptides of human epididymis 2 (HE2) family; salt sensitivity, structural dependence and their interaction with outer and cytoplasmic membranes of Escherichia coli. Biochem J 2003; 372:473-83. [PMID: 12628001 PMCID: PMC1223422 DOI: 10.1042/bj20030225] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2003] [Revised: 03/06/2003] [Accepted: 03/11/2003] [Indexed: 11/17/2022]
Abstract
During passage through the epididymis, sperm interact with secreted epididymal proteins that promote maturation, including the acquisition of motility and fertilization competence. Viewed previously as distinct from sperm maturation, host defence capabilities are now recognized functions of the human epididymis 2 (HE2) family of sperm-binding proteins. We analysed the potent dose and time-dependent bactericidal activity of recombinant HE2alpha, HE2beta1 and HE2beta2 and found that the full-length proteins (10 microg/ml or approximately 1 microM) caused more than a 50% decrease in Escherichia coli colony forming units within 15 min. By contrast, human beta-defensin-1, at a similar concentration, required more than 90 min to exhibit similar antibacterial activity. The epididymis-specific lipocalin, LCN6, failed to kill bacteria. Higher concentrations (25-100 microg/ml) of HE2 proteins and a longer duration of treatment resulted in near total inhibition of bacterial growth. The C-terminal peptides of HE2alpha, HEbeta1 and HEbeta2 proteins exhibited antibacterial activity similar to their full-length counterparts, indicating that the antibacterial activity of HE2 proteins resides in these C-terminal regions. Antibacterial activities of HE2 proteins and peptides were slightly inhibited by NaCl concentrations of up to 150 mM, while human beta-defensin-1 activity was nearly eliminated. Reduction and alkylation of disulphide bonds in HE2 proteins and their C-terminal peptides abolished their antibacterial activity. Consistent with the ability to kill bacteria, full-length HE2 proteins and C-terminal peptides caused rapid dose-dependent permeabilization of outer and cytoplasmic E. coli membranes. A much longer exposure time was required for human beta-defensin-1-mediated permeabilization of membranes, suggesting a possible difference in mode of action compared with the HE2 antibacterial peptides.
Collapse
Affiliation(s)
- Suresh Yenugu
- Laboratories for Reproductive Biology, Department of Pediatrics, University of North Carolina, Chapel Hill 27599-7500, USA
| | | | | | | | | | | |
Collapse
|
30
|
Tam JP, Lu YA, Yang JL. Correlations of cationic charges with salt sensitivity and microbial specificity of cystine-stabilized beta -strand antimicrobial peptides. J Biol Chem 2002; 277:50450-6. [PMID: 12399464 DOI: 10.1074/jbc.m208429200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The electrostatic interaction of the charge cluster of an amphipathic peptide antibiotic with microbial membranes is a salt-sensitive step that often determines organism specificity. We have examined the correlation between charge clusters and salt insensitivity and microbial specificity in linear, cyclic, and retro-isomeric cystine-stabilized beta-strand (CSbeta) tachyplesin (TP) in a panel of 10 test organisms. Cyclic tachyplesins consisting of 14 and 18 amino acids are constrained by an end-to-end peptide backbone and two or three disulfide bonds to cross-brace the anti-parallel beta-strand that approximates a "beta-tile" structure. Circular dichroism measurements of beta-tile TPs showed that they displayed ordered structures. Control peptides containing the same number of basic amino acids as TP but lacking disulfide constraints were highly salt sensitive. Cyclic TP analogues with six cationic charges were more broadly active and salt-insensitive than those with fewer cationic charges. Reducing their proximity or number of cationic charges, particularly those with three or fewer basic amino acids, led to a significant decrease in potency and salt insensitivity, but an increased selectivity to certain Gram-positive bacteria. An end-group effect of the dibasic N-terminal Lys of TP in the open-chain TP and its retroisomer was observed in certain Gram-negative bacteria under high-salt conditions, an effect that was not found in the cyclic analogs. These results suggest that a stable folded structure together with three or more basic amino acids closely packed in a charged region in CSbeta peptides is important for salt insensitivity and organism specificity.
Collapse
Affiliation(s)
- James P Tam
- Department of Microbiology and Immunology, Vanderbilt University, A5119 MCN, Nashville, Tennessee 37232-2363, USA.
| | | | | |
Collapse
|
31
|
Park SH, Kim HE, Kim CM, Yun HJ, Choi EC, Lee BJ. Role of proline, cysteine and a disulphide bridge in the structure and activity of the anti-microbial peptide gaegurin 5. Biochem J 2002; 368:171-82. [PMID: 12164787 PMCID: PMC1222972 DOI: 10.1042/bj20020385] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2002] [Revised: 07/25/2002] [Accepted: 08/06/2002] [Indexed: 11/17/2022]
Abstract
Gaegurin 5 (GGN5) is a cationic 24-residue anti-microbial peptide isolated from the skin of a Korean frog, Rana rugosa. It contains a central proline residue and an intra-residue disulphide bridge in its C-terminus, which are common to the anti-microbial peptides found in Ranidae. We determined the solution structure of GGN5 bound to SDS micelles for the first time and investigated the role of proline, cysteine and a disulphide bridge on the structure and activity of GGN5. GGN5 adopts an amphipathic alpha-helical structure spanning residues 3-20 kinked around Pro-14, which allows the hydrophobic residues to reside in the concave helical region, and a disulphide-bridged loop-like conformation in its C-terminus. By replacement of proline with alanine (PAGGN5), a straight and rigid helix was formed in the central region and was more stable than the kinked helix. Reduction of a disulphide bridge in the C-terminus (GGN5SH) maintained the loosely ordered loop-like conformation, while the replacement of two cysteines with serines (CSGGN5) caused the C-terminal conformation to be completely disordered. The magnitude of anti-microbial activity of the peptides was closely related to their helical stability in the order PAGGN5>GGN5>GGN5SH>CSGGN5, suggesting that the helical stability of the peptides is important for anti-microbial activity. On the other hand, the significant increase of haemolytic activity of PAGGN5 implies that a helical kink of GGN5 could be involved in the selectivity of target cells. The location of GGN5 and PAGGN5, analysed using paramagnetic probes, was mainly at the surface of SDS micelles, although the location of the N-terminal region was slightly different between them.
Collapse
Affiliation(s)
- Sang-Ho Park
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea
| | | | | | | | | | | |
Collapse
|
32
|
Kobayashi S. [Bacteria-selective synergism between the antimicrobial peptides magainin 2 and tachyplesin I: toward cocktail therapy]. YAKUGAKU ZASSHI 2002; 122:967-73. [PMID: 12440153 DOI: 10.1248/yakushi.122.967] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Magainin 2 and tachyplesin I (T-SS) are membrane-permeabilizing antimicrobial peptides discovered in frog skin and horseshoe crab hemolymph, respectively. They are classified into different secondary structural classes, i.e., alpha-helix and cyclic beta-sheet, respectively. We found that F5W-magainin 2 (MG2) and T-SS showed marked synergistic effects against gram-negative and-positive bacteria without enhancing hemolytic activity as a measure of toxicity. The results of dye-release experiments using liposomes suggested that the selective synergism is mainly due to anionic phospholipid-specific synergism in membrane permeabilization. Furthermore, the cyclic structure of T-SS was found to be necessary for synergism because a linear analogue of T-SS did not show good synergism with MG2. These novel observations suggest the possibility of development of cocktail therapeutic regimens using combinations of antimicrobial peptides.
Collapse
Affiliation(s)
- Satoe Kobayashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| |
Collapse
|
33
|
Hunter HN, Fulton DB, Ganz T, Vogel HJ. The solution structure of human hepcidin, a peptide hormone with antimicrobial activity that is involved in iron uptake and hereditary hemochromatosis. J Biol Chem 2002; 277:37597-603. [PMID: 12138110 DOI: 10.1074/jbc.m205305200] [Citation(s) in RCA: 256] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The antibacterial and antifungal peptide hepcidin (LEAP-1) is expressed in the liver. This circulating peptide has recently been found to also act as a signaling molecule in iron metabolism. As such, it plays an important role in hereditary hemochromatosis, a serious iron overload disease. In this study, we report the solution structures of the hepcidin-20 and -25 amino acid peptides determined by standard two-dimensional (1)H NMR spectroscopy. These small cysteine-rich peptides form a distorted beta-sheet with an unusual vicinal disulfide bridge found at the turn of the hairpin, which is probably of functional significance. Both peptides exhibit an overall amphipathic structure with six of the eight Cys involved in maintaining interstrand connectivity. Hepcidin-25 assumes major and minor conformations centered about the Pro residue near the N-terminal end. Further NMR diffusion studies indicate that hepcidin-20 exists as a monomer in solution, whereas hepcidin-25 readily aggregates, a property that may contribute to the different activities of the two peptides. The nuclear Overhauser enhancement spectroscopy spectra of the hepcidin-25 aggregates indicate an interface for peptide interactions that again involves the first five residues from the N-terminal end.
Collapse
Affiliation(s)
- Howard N Hunter
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | | | | | | |
Collapse
|
34
|
Zhao H, Kinnunen PKJ. Binding of the antimicrobial peptide temporin L to liposomes assessed by Trp fluorescence. J Biol Chem 2002; 277:25170-7. [PMID: 11991956 DOI: 10.1074/jbc.m203186200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The structure and membrane topology of the antimicrobial peptide temporin L (FVQWFSKFLGRIL- NH(2)) were studied using liposomes as model bilayers. Circular dichroic spectra revealed temporin L to adopt an alpha-helical conformation when bound to liposomes. Binding of temporin L to liposomes induced significant blue shifts of the emission spectra of the single Trp residue (Trp(4)) and also changed its quantum yield. The observed changes in the characteristics of the Trp(4) fluorescence are in keeping with the insertion of this residue into the hydrophobic region of the liposomal bilayers. Access of the aqueous quencher acrylamide to Trp(4) decreased in the sequence 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC)/cholesterol (X(chol) = 0.1) > SOPC > SOPC/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG, X(POPG) = 0.1) > SOPC/POPG (X(POPG) = 0.2) approximately SOPC/POPG (X(POPG) = 0.4), where X represents molar fraction of the indicated lipid. Whereas quenching of Trp(4) by brominated phospholipids was significant in SOPC liposomes, the quenching efficiency was enhanced when the vesicles contained POPG. The depth of insertion of Trp(4) into lipid bilayers was calculated by both the parallax method and distribution analysis and revealed this residue to reside at an average distance of d approximately 8.0 +/- 0.5 A from the center of both SOPC and SOPC/POPG bilayers. However, in the presence of cholesterol, d was increased to 9.5 +/- 0.5 A, thus revealing Trp(4) to become accommodated more superficially in the bilayer. The above data suggest the presence of two populations of temporin L in SOPC- and POPG-containing membranes with parallel and perpendicular orientation with respect to the plane of the membrane surface.
Collapse
Affiliation(s)
- Hongxia Zhao
- Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine, University of Helsinki, Finland
| | | |
Collapse
|
35
|
Hirakura Y, Kobayashi S, Matsuzaki K. Specific interactions of the antimicrobial peptide cyclic beta-sheet tachyplesin I with lipopolysaccharides. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1562:32-6. [PMID: 11988219 DOI: 10.1016/s0005-2736(02)00358-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cyclic beta-sheet antimicrobial peptide tachyplesin I (T-SS) was found to show 280-fold higher affinity for lipopolysaccharides (LPS) compared with acidic phospholipids, whereas the linear alpha-helical peptide F5W-magainin 2 (MG2) could not discriminate between LPS and acidic phospholipids. The recognition site was the lipid A moiety and the cyclic structure was crucial to this specific binding. The cyclic structure also endowed the peptide with very rapid outer membrane (OM) permeabilization.
Collapse
Affiliation(s)
- Yutaka Hirakura
- Advanced Research Center for Human Sciences, Waseda University, Nishi-Tokyo, Tokyo 202-0021, Japan
| | | | | |
Collapse
|
36
|
Zhao H, Mattila JP, Holopainen JM, Kinnunen PK. Comparison of the membrane association of two antimicrobial peptides, magainin 2 and indolicidin. Biophys J 2001; 81:2979-91. [PMID: 11606308 PMCID: PMC1301762 DOI: 10.1016/s0006-3495(01)75938-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Interactions of two antimicrobial peptides, magainin 2 and indolicidin, with three different model biomembranes, namely, monolayers, large unilamellar vesicles (LUVs), and giant liposomes, were studied. Insertion of both peptides into lipid monolayers was progressively enhanced when the content of an acidic phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) in a film of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) was increased. Indolicidin and magainin 2 penetrated also into lipid monolayers containing cholesterol (mole fraction, X = 0.1). Membrane association of magainin 2 attenuated lipid lateral diffusion in POPG-containing LUVs as revealed by the decrease in the excimer/monomer fluorescence ratio I(e)/I(m) for the pyrene fatty-acid-containing phospholipid derivative 1-palmitoyl-2-[10-(pyren-1-yl) decanoyl]-sn-glycero-3-phospho-rac-glycerol (PPDPG). Likewise, an increase in steady-state fluorescence anisotropy of the membrane-incorporated diphenylhexatriene (DPH) was observed, revealing magainin 2 to increase acyl chain order and induce segregation of acidic phospholipids. Similar effects were observed for indolicidin. The topological effects of magainin 2 and indolicidin on phospholipid membranes were investigated using optical microscopy of giant vesicles. Magainin 2 had essentially no influence on either SOPC or SOPC:cholesterol (X = 0.1) giant liposomes. However, effective vesiculation was observed when acidic phospholipid (X(PG) = 0.1) was included in the giant vesicles. Indolicidin caused only a minor shrinkage of giant SOPC vesicles whereas the formation of endocytotic vesicles was observed when the giant liposome contained POPG (X(PG) = 0.1). Interestingly, for indolicidin, vesiculation was also observed for giant vesicles composed of SOPC/cholesterol (X(chol) = 0.1). Possible mechanisms of membrane transformation induced by these two peptides are discussed.
Collapse
Affiliation(s)
- H Zhao
- Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine, University of Helsinki, FIN-00014 Helsinki, Finland
| | | | | | | |
Collapse
|
37
|
Zhang L, Rozek A, Hancock RE. Interaction of cationic antimicrobial peptides with model membranes. J Biol Chem 2001; 276:35714-22. [PMID: 11473117 DOI: 10.1074/jbc.m104925200] [Citation(s) in RCA: 295] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A series of natural and synthetic cationic antimicrobial peptides from various structural classes, including alpha-helical, beta-sheet, extended, and cyclic, were examined for their ability to interact with model membranes, assessing penetration of phospholipid monolayers and induction of lipid flip-flop, membrane leakiness, and peptide translocation across the bilayer of large unilamellar liposomes, at a range of peptide/lipid ratios. All peptides were able to penetrate into monolayers made with negatively charged phospholipids, but only two interacted weakly with neutral lipids. Peptide-mediated lipid flip-flop generally occurred at peptide concentrations that were 3- to 5-fold lower than those causing leakage of calcein across the membrane, regardless of peptide structure. With the exception of two alpha-helical peptides V681(n) and V25(p,) the extent of peptide-induced calcein release from large unilamellar liposomes was generally low at peptide/lipid molar ratios below 1:50. Peptide translocation across bilayers was found to be higher for the beta-sheet peptide polyphemusin, intermediate for alpha-helical peptides, and low for extended peptides. Overall, whereas all studied cationic antimicrobial peptides interacted with membranes, they were quite heterogeneous in their impact on these membranes.
Collapse
Affiliation(s)
- L Zhang
- Department of Microbiology and Immunology, University of British Columbia, 300-6174 University Boulevard, Vancouver, British Columbia V6T 1Z3, Canada
| | | | | |
Collapse
|
38
|
Matsuzaki K, Murase O, Sugishita K, Yoneyama S, Akada K, Ueha M, Nakamura A, Kobayashi S. Optical characterization of liposomes by right angle light scattering and turbidity measurement. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1467:219-26. [PMID: 10930524 DOI: 10.1016/s0005-2736(00)00223-6] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Liposomes have frequently been used as models of biomembranes or vehicles for drug delivery. However, the systematic characterization of lipid vesicles by right angle light scattering and turbidity has not been carried out despite the usefulness of such studies for size estimation. In this study, liposomes of various sizes were prepared by sonication and extrusion. The mean cumulant radii of the vesicles were determined by dynamic light scattering. The lamellarities were estimated based on fluorescence quenching of N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)dipalmitoyl-L-alpha-phosph ati dylethanolamine by sodium dithionite. Right angle light scattering intensity and optical density at 436 nm per unit lipid concentration were measured as a function of vesicle radius. With a vesicle radius < or =100 nm, the optical parameters could be well explained by the Rayleigh-Gans-Debye theory in which the liposomes were modeled as homogeneous spheres with mean refractive indices determined by the volume fractions of lipids in vesicles.
Collapse
Affiliation(s)
- K Matsuzaki
- Graduate School of Biostudies and Graduate School of Pharmaceutical Sciences, Kyoto, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Abstract
Antibiotic peptides are a key component of the innate immune systems of most multicellular organisms. Despite broad divergences in sequence and taxonomy, most antibiotic peptides share a common mechanism of action, i.e., membrane permeabilization of the pathogen. This review provides a general introduction to the subject, with emphasis on aspects such as structural types, post-translational modifications, mode of action or mechanisms of resistance. Some of these questions are treated in depth in other reviews in this issue. The review also discusses the role of antimicrobial peptides in nature, including several pathological conditions, as well as recent accounts of their application at the preclinical level.
Collapse
Affiliation(s)
- D Andreu
- Department of Organic Chemistry, Universitat de Barcelona, Spain.
| | | |
Collapse
|
40
|
Castano S, Desbat B, Dufourcq J. Ideally amphipathic beta-sheeted peptides at interfaces: structure, orientation, affinities for lipids and hemolytic activity of (KL)(m)K peptides. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1463:65-80. [PMID: 10631295 DOI: 10.1016/s0005-2736(99)00175-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Designed to model ideally amphipathic beta-sheets, the minimalist linear (KL)(m)K peptides (m=4-7) were synthesized and proved to form stable films at the air/water interface, they insert into compressed dimyristoylphosphatidylcholine monolayers and interact with egg phosphatidylcholine vesicles. Whatever the interface or the lateral pressure applied to the films, FT-IR and polarization-modulated IRRAS spectroscopy developed in situ on the films indicated that all the peptides totally fold into intermolecular antiparallel beta-sheets. Calculated spectra of the amide region allowed us to define the orientation of the beta-strands compared to the interface. It is concluded that such beta-sheets remain flat-oriented without deep perturbation of zwitterionic phospholipids. Dansyl labelling at the N-terminus indicates that all the peptides are monomeric at a low concentration in aqueous buffer and bind to lipids with similar Dns burying. The affinities for zwitterionic lecithin mono- and bilayers, quantitatively estimated from buffer to lipid partition constants, monotonically increased with peptide length, indicating that hydrophobicity is a limiting parameter for lipid and membrane affinities. Peptides induced permeability increases on zwitterionic liposomes, they are strongly hemolytic towards human erythrocytes and their activity increases concurrently with length. Taking into account the lipid affinity, a hemolytic efficiency can be defined: at the same amount of peptide bound, this efficiency strongly increases with the peptide length. It is proposed that the first determinant step of membrane disturbance is the invasion of the outer membrane leaflet by these ideally amphipathic beta-sheeted structures lying flat at the interface, like large rafts depending on the number of beta-strands.
Collapse
Affiliation(s)
- S Castano
- Centre de Recherche Paul Pascal, Avenue A. Schweitzer, CNRS, 33600, Pessac, France
| | | | | |
Collapse
|
41
|
Matsuzaki K. Why and how are peptide-lipid interactions utilized for self-defense? Magainins and tachyplesins as archetypes. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1462:1-10. [PMID: 10590299 DOI: 10.1016/s0005-2736(99)00197-2] [Citation(s) in RCA: 714] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Animals as well as plants defend themselves against invading pathogenic microorganisms utilizing cationic antimicrobial peptides, which rapidly kill various microbes without exerting toxicity against the host. Physicochemical peptide-lipid interactions provide attractive mechanisms for innate immunity. Many of these peptides form cationic amphipathic secondary structures, typically alpha-helices and beta-sheets, which can selectively interact with anionic bacterial membranes by the aid of electrostatic interactions. Rapid, peptide-induced membrane permeabilization is an effective mechanism of antimicrobial action. This review article summarizes interactions with lipid bilayers of magainins (alpha-helix) and tachyplesins (beta-sheet) discovered in frog skin and horseshoe crab hemolymph, respectively, as archetypes, emphasizing that the mode of interaction is strongly dependent on the physicochemical properties not only of the peptide, but also of the target membrane.
Collapse
Affiliation(s)
- K Matsuzaki
- Graduate School of Biostudies, Kyoto University, Yoshida-Shimoadachi-Cho 46-29, Sakyo-ku, Kyoto, Japan.
| |
Collapse
|
42
|
Shai Y. Mechanism of the binding, insertion and destabilization of phospholipid bilayer membranes by alpha-helical antimicrobial and cell non-selective membrane-lytic peptides. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1462:55-70. [PMID: 10590302 DOI: 10.1016/s0005-2736(99)00200-x] [Citation(s) in RCA: 1380] [Impact Index Per Article: 55.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Permeation of the cell membrane leading to cell death is a mechanism used by a large number of membrane-lytic peptides. Some are linear, mostly helical, and others contain one or more disulfide bonds forming beta-sheet or both beta-sheet and alpha-helix structures. They are all soluble in solution but when they reach the target membrane, conformational changes occur which let them associate with and lyse the membrane. Some lytic peptides are not cell-selective and lyse different microorganisms and normal mammalian cells, while others are specific to either type of cells. Despite extensive studies, the mode of action of membrane-lytic peptides is not fully understood and the basis for their selectivity towards specific target cells is not known. Many studies have shown that peptide-lipid interactions leading to membrane permeation play a major role in their activity. Membrane permeation by amphipathic alpha-helical peptides has been proposed to occur via one of two general mechanisms: (i) transmembrane pore formation via a 'barrel-stave' mechanism; and (ii) membrane destruction/solubilization via a 'carpet' mechanism. This review, which is focused on the different stages of membrane permeation induced by representatives of amphipathic alpha-helical antimicrobial and cell non-selective lytic peptides distinguishes between the 'carpet' mechanism, which holds for antimicrobial peptides versus the 'barrel-stave' mechanism, which holds for cell non-selective lytic peptides.
Collapse
Affiliation(s)
- Y Shai
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
| |
Collapse
|
43
|
|
44
|
Matsuzaki K, Sugishita K, Harada M, Fujii N, Miyajima K. Interactions of an antimicrobial peptide, magainin 2, with outer and inner membranes of Gram-negative bacteria. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1327:119-30. [PMID: 9247173 DOI: 10.1016/s0005-2736(97)00051-5] [Citation(s) in RCA: 271] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Magainin peptides, isolated from Xenopus skin, have broad spectra of antimicrobial activity and low toxicities to normal eukaryotic cells, thus being good candidates for therapeutic agents. The mechanism of action is considered to be the permeabilization of bacterial membranes. A number of studies using lipid vesicles have elucidated its molecular detail. However, their interactions with bacteria are not yet well understood. In this paper, we synthesized several magainin analogs with different charges (0 to +6) and hydrophobicities, and systematically studied their interactions with the outer and inner membranes of three species of Gram-negative bacteria (Escherichia coli, Acinetobacter calcoaceticus, Proteus vulgaris). The treatment of the E. coli cells with native magainin 2 (+4) immediately induced the efflux of the intracellular K+ ions and the cell death. A number of blebs were formed on the bacterial surface and the outer membrane became leaky. An increase in the peptide's positive charge enhanced the outer membrane permeabilization and the bactericidal activity. The cationic peptides also effectively permeabilized the inner membranes rich in acidic phospholipids, indicating the importance of electrostatic interactions. Substitution of Trp for Phe simultaneously increased the bactericidal activity and the hemolytic activity. A strategy to develop potent antimicrobial peptides was discussed on the basis of these results.
Collapse
Affiliation(s)
- K Matsuzaki
- Faculty of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Japan.
| | | | | | | | | |
Collapse
|
45
|
Harwig SS, Waring A, Yang HJ, Cho Y, Tan L, Lehrer RI. Intramolecular disulfide bonds enhance the antimicrobial and lytic activities of protegrins at physiological sodium chloride concentrations. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 240:352-7. [PMID: 8841398 DOI: 10.1111/j.1432-1033.1996.0352h.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Protegrins are 2-kDa antimicrobial peptides that contain 16-18 amino acid residues and two intramolecular disulfide bonds. We studied the contribution of these disulfide bonds to the bactericidal activity of protegrins in physiological concentrations of NaCl by comparing protegrin PG-1 with variants that lacked one or both cysteine disulfides. Whereas the bactericidal and liposome-lytic properties of protegrin PG-1 were enhanced by adding 100 mM NaCl to the phosphate-buffered medium, NaCl addition strongly inhibited the effects of its linearized, disulfide-free variant, [A6, A8, A13, A15]protegrin-1. Whereas protegrin PG-1 manifested beta-sheet structure by CD (circular dichroism) and ATR-FTIR (attenuated-total-reflectance-Fourier-transform-infrared) spectroscopy in buffer or membrane-mimetic environments, [A6, A8, A13, A15]protegrin-1 manifested disordered structure in phosphate buffer and alpha-helical characteristics in membrane-mimetic environments. Both single-disulfide protegrin variants, [A8, A13]protegrin-1 and [A6, A15]protegrin-1, assumed beta-sheet conformations with liposomes that simulated bacterial membranes, and both retained substantial bactericidal activity when 100 mM NaCl was present. These findings demonstrate that the intramolecular disulfide bonds of protegrins are required for their antiparallel beta-sheet conformation in membrane-mimetic environments and for their potent antimicrobial activity in media containing NaCl concentrations comparable to those found in serum and extracellular fluids.
Collapse
Affiliation(s)
- S S Harwig
- Department of Medicine, UCLA 90095-1690, USA
| | | | | | | | | | | |
Collapse
|
46
|
Aumelas A, Mangoni M, Roumestand C, Chiche L, Despaux E, Grassy G, Calas B, Chavanieu A. Synthesis and solution structure of the antimicrobial peptide protegrin-1. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 237:575-83. [PMID: 8647100 DOI: 10.1111/j.1432-1033.1996.0575p.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Protegrins are members of a family of five Cys-rich, cationic antimicrobial peptides recently isolated from porcine cells. We have synthesised an 18-amino-acid peptide that corresponds to protegrin-1. After Cys oxidation, the peptide has bactericidal activity against gram-positive and gram-negative bacteria, similar to that described for the natural peptide. The solution structure of protegrin-1 was investigated by means of 1H-NMR spectroscopy in water and in (CD3)2SO, with distance-geometry and simulated-annealing calculations. The C6-C15 and C8-C13 disulfide pattern was determined on the basis of NMR-derived constraints. These two parallel disulfide bridges stabilised a beta-sheet structure which comprised two antiparallel strands (residues 5-9 and 12-16) linked by a distorted beta-turn (residues 9-12). The N-terminus and C-terminus were essentially disordered. The distribution of hydrophobic and hydrophilic residues at the peptide surface was found to be a structural feature shared with tachyplesin-1, a related peptide which displays cytolytic activity, and, to a lesser extent, with mammalian defensins. These findings led us to assume that the distribution pattern could be required for the cytolytic activity of these peptides.
Collapse
Affiliation(s)
- A Aumelas
- Centre de Biochimie Structurale, UMR C9955, U414 INSERM, Faculté de Pharmacie, Montpellier, France
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Mangoni ME, Aumelas A, Charnet P, Roumestand C, Chiche L, Despaux E, Grassy G, Calas B, Chavanieu A. Change in membrane permeability induced by protegrin 1: implication of disulphide bridges for pore formation. FEBS Lett 1996; 383:93-8. [PMID: 8612801 DOI: 10.1016/0014-5793(96)00236-0] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Protegrin 1 (PG-1) is a naturally occurring cationic antimicrobial peptide that is 18 residues long, has an aminated carboxy terminus and contains two disulphide bridges. Here, we investigated the antimicrobial activity of PG-1 and three linear analogues. Then, the membrane permeabilisation induced by these peptides was studied upon Xenopus laevis oocytes by electrophysiological methods. From the results obtained, we concluded that protegrin is able to form anion channels. Moreover, it seems clear that the presence of disulphide bridges is a prerequisite for the pore formation at the membrane level and not for the antimicrobial activity.
Collapse
Affiliation(s)
- M E Mangoni
- Centre de Recherches de Biochimie Macromoléculaire, CNRS-INSERM, Montpellier, France
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Matsuzaki K, Sugishita K, Fujii N, Miyajima K. Molecular basis for membrane selectivity of an antimicrobial peptide, magainin 2. Biochemistry 1995; 34:3423-9. [PMID: 7533538 DOI: 10.1021/bi00010a034] [Citation(s) in RCA: 330] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Magainin peptides, isolated from Xenopus skin, kill bacteria by permeabilizing their cell membranes whereas they do not lyse erythrocytes. To elucidate the rationale for this membrane selectivity, we compared the effects of the membrane lipid composition and the transmembrane potential on the membrane-lytic power of magainin 2 with that of hemolytic melittin. The activity of magainin to zwitterionic phospholipids constituting the erythrocyte surface was extremely weak compared with that of melittin, and acidic phospholipids are necessary for effective action. The presence of sterols reduced the susceptibility of the membrane to magainin. The generation of an inside-negative transmembrane potential enhanced magainin-induced hemolysis. We can conclude that the absence of any acidic phospholipids on the outer monolayer and the abundant presence of cholesterol, combined with the lack of the transmembrane potential, contribute to the protection of erythrocytes from magainin's attack.
Collapse
Affiliation(s)
- K Matsuzaki
- Faculty of Pharmaceutical Sciences, Kyoto University, Japan
| | | | | | | |
Collapse
|
49
|
Haris PI, Chapman D. The conformational analysis of peptides using Fourier transform IR spectroscopy. Biopolymers 1995; 37:251-63. [PMID: 7540054 DOI: 10.1002/bip.360370404] [Citation(s) in RCA: 431] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Fourier transform infrared spectroscopy (FTIR) can be used for conformational analysis of peptides in a wide range of environments. Measurements can be performed in aqueous solution, organic solvents, detergent micelles as well as in phospholipid membranes. Information on the secondary structure of peptides can be derived from the analysis of the strong amide I band. Orientation of secondary structural elements within a lipid bilayer matrix can be determined by means of polarized attenuated total reflectance-FTIR spectroscopy. Hydrogen-deuterium exchange can be monitored by the analysis of the amide II band. This review gives some example of peptide systems studied by FTIR spectroscopy. Studies on alamethicin and alpha-aminoisobutyric acid containing peptides have shown that FTIR spectroscopy is a sensitive tool for identifying 3(10)-helical structures. Changes in the structure of the magainins upon interaction with charged lipids were detected using FTIR spectroscopy. Tachyplesin is an example of a beta-sheet containing membrane active peptide. Polarized ir spectroscopy reveals that the antiparallel beta-sheet structures of tachyplesin are oriented parallel to the membrane surface. Synthesis of peptides corresponding to functionally/structurally important regions of large proteins is becoming increasingly popular. FTIR spectroscopy has been used to analyze the structure of synthetic peptides corresponding to the ion-selective pore of the voltage-gated potassium channel. In biomembrane systems these peptides adopt a highly helical structure. Under conditions, where these peptides are aggregated the presence of some intermolecular beta-sheet structure can also be detected.
Collapse
Affiliation(s)
- P I Haris
- Department of Protein and Molecular Biology, Royal Free Hospital School of Medicine, University of London, United Kingdom
| | | |
Collapse
|