1
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Shen H, Zhang N, Kong X, Wang N, Hu HG, Cong W, Liu C. Benzyl stapled modification and anticancer activity of antimicrobial peptide A4K14-Citropin 1.1. Bioorg Med Chem Lett 2023; 96:129499. [PMID: 37804993 DOI: 10.1016/j.bmcl.2023.129499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 09/25/2023] [Accepted: 10/04/2023] [Indexed: 10/09/2023]
Abstract
A4K14-Citropin 1.1 (GLFAVIKKVASVIKGL-NH2) is a derived antimicrobial peptide (AMP) with a more stable α-helical structure at the C-terminal compared to prototype Citropin 1.1 which was obtained from glandular skin secretions of Australian freetail lizards. In a previous report, A4K14-Citropin 1.1 has been considered as an anti-cancer lead compound. However, linear peptides are difficult to maintain stable secondary structure, resulted in poor pharmacokinetic properties. In this study, we designed and synthesized a series of benzyl-stapled derivatives of A4K14-Citropin 1.1. And their physical and chemical properties, as well as biological activity, were both explored. The result showed that AC-CCSP-2-o and AC-CCSP-3-o exhibited a higher degree of helicity and greater anti-cancer activity compared with the prototype peptide. Besides, there was no significant difference in the hemolytic effect between the stapled peptides and the prototype peptide. AC-CCSP-2-o and AC-CCSP-3-o could serve as promising anti-cancer lead compounds for the novel anti-cancer drug development.
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Affiliation(s)
- Huaxing Shen
- School of Medicine, Shanghai University, Shanghai 200444, China
| | - Nan Zhang
- School of Medicine, Shanghai University, Shanghai 200444, China
| | - Xianglong Kong
- School of Pharmacy, Weifang Medical University, Weifang 261053, PR. China
| | - Nan Wang
- School of Medicine, Shanghai University, Shanghai 200444, China
| | - Hong-Gang Hu
- School of Medicine, Shanghai University, Shanghai 200444, China
| | - Wei Cong
- School of Medicine, Shanghai University, Shanghai 200444, China.
| | - Chao Liu
- School of Medicine, Shanghai University, Shanghai 200444, China.
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2
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Islam MM, Asif F, Zaman SU, Arnab MKH, Rahman MM, Hasan M. Effect of charge on the antimicrobial activity of alpha-helical amphibian antimicrobial peptide. CURRENT RESEARCH IN MICROBIAL SCIENCES 2023; 4:100182. [PMID: 36926259 PMCID: PMC10011193 DOI: 10.1016/j.crmicr.2023.100182] [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: 03/06/2023] Open
Abstract
Antibiotic resistance is a severe threat to the world's public health, which has increased the need to discover novel antibacterial molecules. In this context, an emerging class of naturally occurring short peptide molecules called antimicrobial peptides (AMPs) has been considered potent antibacterial agents. Amphibians are one of the significant sources of AMPs, which have been extensively studied for the last few decades. Most amphibian AMPs are cationic, and several of these cationic AMPs adopt a well-defined alpha-helical structure in the presence of bacterial membranes. These cationic alpha-helical amphibian AMPs (CαAMPs) can selectively and preferentially bind with the negatively charged surfaces of Gram-positive and Gram-negative bacteria through electrostatic interaction, considered the main reason for their antibacterial activities. Here, we categorized these CαAMPs according to their charge, and to calculate the charge density; we divided the charge of each peptide by its corresponding length. To investigate the effect of charge among these categories, charge or charge density under each charge category was plotted against their corresponding minimum inhibitory concentration (MIC). Moreover, the effect of charge modification of some CαAMPs under specific charge categories in the context of MIC and hemolysis was also discussed. The information in this review will help us understand the antibacterial activity of accessible CαAMPs depending on each charge category across species. Additionally, this study suggests that designing novel functional antibacterial agents requires charge modification optimally.
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Affiliation(s)
- Md Monirul Islam
- Department of Pharmacy, Noakhali Science and Technology University, Noakhali 3814, Bangladesh
| | - Fahim Asif
- Department of Pharmacy, Jagannath University, Dhaka 1100, Bangladesh
| | - Sabbir Uz Zaman
- Department of Pharmacy, Jagannath University, Dhaka 1100, Bangladesh
| | | | | | - Moynul Hasan
- Department of Pharmacy, Jagannath University, Dhaka 1100, Bangladesh
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3
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Zhao J, Ge G, Huang Y, Hou Y, Hu SQ. Butelase 1-Mediated Enzymatic Cyclization of Antimicrobial Peptides: Improvements on Stability and Bioactivity. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:15869-15878. [PMID: 36471508 DOI: 10.1021/acs.jafc.2c06588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Antimicrobial peptides (AMPs) have broad-spectrum antibacterial properties and safety as food preservatives, whereas the stability and antibacterial activity require improvement. Here, the "head-to-tail" cyclization of linear AMP GKE was catalyzed by butelase 1, which resulted in an improved pronouncedly antibacterial effect. Cell morphology and propidium iodide uptake revealed that the increased membrane permeability was one of the bacteriostatic mechanisms of GKE and could be enhanced after cyclization. As cyclic GKE (cGKE) exhibited more stability than the linear counterpart under the microorganism culture environment, the increase in effective bacteriostatic concentration should be a reason for the superior antibacterial effect. Moreover, cGKE exhibited the ordered secondary structure, while GKE possessed a similar structure only in sodium dodecyl sulfate micelles. The structure was also beneficial to improve the antibacterial activity caused by the increased affinity of cGKE to the membranes. Overall, butelase 1-mediated cyclization is a promising strategy for enhancing the antibacterial activity of linear AMPs.
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Affiliation(s)
- Jinsong Zhao
- Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - Ge Ge
- Beijing Food Safety Monitoring and Risk Assessment Center, Beijing 100094, China
| | - Yanbo Huang
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Yi Hou
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Song-Qing Hu
- Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China
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4
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Ragonis-Bachar P, Rayan B, Barnea E, Engelberg Y, Upcher A, Landau M. Natural Antimicrobial Peptides Self-assemble as α/β Chameleon Amyloids. Biomacromolecules 2022; 23:3713-3727. [PMID: 35947777 DOI: 10.1021/acs.biomac.2c00582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amyloid protein fibrils and some antimicrobial peptides (AMPs) share biophysical and structural properties. This observation suggests that ordered self-assembly can act as an AMP-regulating mechanism, and, vice versa, that human amyloids play a role in host defense against pathogens, as opposed to their common association with neurodegenerative and systemic diseases. Based on previous structural information on toxic amyloid peptides, we developed a sequence-based bioinformatics platform and, led by its predictions, experimentally identified 14 fibril-forming AMPs (ffAMPs) from living organisms, which demonstrated cross-β and cross-α amyloid properties. The results support the amyloid-antimicrobial link. The high prevalence of ffAMPs produced by amphibians and marine creatures among other species suggests that they confer unique advantageous properties in distinctive environments, potentially providing stability and adherence properties. Most of the newly identified 14 ffAMPs showed lipid-induced and/or time-dependent secondary structure transitions in the fibril form, indicating structural and functional cross-α/β chameleons. Specifically, ffAMP cytotoxicity against human cells correlated with the inherent or lipid-induced α-helical fibril structure. The findings raise hypotheses about the role of fibril secondary structure switching in regulation of processes, such as the transition between a stable storage conformation and an active state with toxicity against specific cell types.
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Affiliation(s)
- Peleg Ragonis-Bachar
- Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Bader Rayan
- Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Eilon Barnea
- Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Yizhaq Engelberg
- Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Alexander Upcher
- Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Meytal Landau
- Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.,European Molecular Biology Laboratory (EMBL) and Centre for Structural Systems Biology, Hamburg 22607, Germany
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5
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Zheng X, Zhu L, Li T, Xu W, Liu D, Sheng J, Cao H, Shi Y, Wang F. Improve Stability of Bioactive Peptides by Enzymatic Modular Synthesis of Peptides with O-Linked Sialyl Lewis x. ACS Catal 2021. [DOI: 10.1021/acscatal.1c00955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Xiaoju Zheng
- Key Laboratory of Chemical Biology (Ministry of Education), Institute of Biochemical and Biotechnological Drug, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Lin Zhu
- Key Laboratory of Chemical Biology (Ministry of Education), Institute of Biochemical and Biotechnological Drug, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Tianlu Li
- Laboratory of Carbohydrate Chemistry and Glycobiology, National Glycoengineering Research Center, Shandong University, Jinan 250012, China
| | - Wenjia Xu
- Key Laboratory of Chemical Biology (Ministry of Education), Institute of Biochemical and Biotechnological Drug, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Dongke Liu
- Key Laboratory of Chemical Biology (Ministry of Education), Institute of Biochemical and Biotechnological Drug, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Juzheng Sheng
- Key Laboratory of Chemical Biology (Ministry of Education), Institute of Biochemical and Biotechnological Drug, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Hongzhi Cao
- Laboratory of Carbohydrate Chemistry and Glycobiology, National Glycoengineering Research Center, Shandong University, Jinan 250012, China
| | - Yikang Shi
- Laboratory of Carbohydrate Chemistry and Glycobiology, National Glycoengineering Research Center, Shandong University, Jinan 250012, China
| | - Fengshan Wang
- Key Laboratory of Chemical Biology (Ministry of Education), Institute of Biochemical and Biotechnological Drug, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
- Laboratory of Carbohydrate Chemistry and Glycobiology, National Glycoengineering Research Center, Shandong University, Jinan 250012, China
- NMPA Key Laboratory for Quality Research and Evaluation of Carbohydrate Based Medicine, Shandong University, Jinan 250012, China
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6
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Müller AT, Posselt G, Gabernet G, Neuhaus C, Bachler S, Blatter M, Pfeiffer B, Hiss JA, Dittrich PS, Altmann KH, Wessler S, Schneider G. Morphing of Amphipathic Helices to Explore the Activity and Selectivity of Membranolytic Antimicrobial Peptides. Biochemistry 2020; 59:3772-3781. [PMID: 32936629 PMCID: PMC7547863 DOI: 10.1021/acs.biochem.0c00565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/07/2020] [Indexed: 01/17/2023]
Abstract
Naturally occurring membranolytic antimicrobial peptides (AMPs) are rarely cell-type selective and highly potent at the same time. Template-based peptide design can be used to generate AMPs with improved properties de novo. Following this approach, 18 linear peptides were obtained by computationally morphing the natural AMP Aurein 2.2d2 GLFDIVKKVVGALG into the synthetic model AMP KLLKLLKKLLKLLK. Eleven of the 18 chimeric designs inhibited the growth of Staphylococcus aureus, and six peptides were tested and found to be active against one resistant pathogenic strain or more. One of the peptides was broadly active against bacterial and fungal pathogens without exhibiting toxicity to certain human cell lines. Solution nuclear magnetic resonance and molecular dynamics simulation suggested an oblique-oriented membrane insertion mechanism of this helical de novo peptide. Temperature-resolved circular dichroism spectroscopy pointed to conformational flexibility as an essential feature of cell-type selective AMPs.
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Affiliation(s)
- Alex T. Müller
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
| | - Gernot Posselt
- Department
of Biosciences, Division of Microbiology, Paris Lodron University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria
| | - Gisela Gabernet
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
| | - Claudia Neuhaus
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
| | - Simon Bachler
- Department
of Biosystems Science and Engineering, ETH
Zurich, Mattenstrasse
26, 4058 Basel, Switzerland
| | - Markus Blatter
- Novartis
Institutes for BioMedical Research, Novartis
Pharma AG, Novartis Campus, 4002 Basel, Switzerland
| | - Bernhard Pfeiffer
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
| | - Jan A. Hiss
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
| | - Petra S. Dittrich
- Department
of Biosystems Science and Engineering, ETH
Zurich, Mattenstrasse
26, 4058 Basel, Switzerland
| | - Karl-Heinz Altmann
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
| | - Silja Wessler
- Department
of Biosciences, Division of Microbiology, Paris Lodron University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria
| | - Gisbert Schneider
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
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7
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Bioinformatic Analysis of 1000 Amphibian Antimicrobial Peptides Uncovers Multiple Length-Dependent Correlations for Peptide Design and Prediction. Antibiotics (Basel) 2020; 9:antibiotics9080491. [PMID: 32784626 PMCID: PMC7459754 DOI: 10.3390/antibiotics9080491] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/29/2020] [Accepted: 08/03/2020] [Indexed: 12/18/2022] Open
Abstract
Amphibians are widely distributed on different continents, except for the polar regions. They are important sources for the isolation, purification and characterization of natural compounds, including peptides with various functions. Innate immune antimicrobial peptides (AMPs) play a critical role in warding off invading pathogens, such as bacteria, fungi, parasites, and viruses. They may also have other biological functions such as endotoxin neutralization, chemotaxis, anti-inflammation, and wound healing. This article documents a bioinformatic analysis of over 1000 amphibian antimicrobial peptides registered in the Antimicrobial Peptide Database (APD) in the past 18 years. These anuran peptides were discovered in Africa, Asia, Australia, Europe, and America from 1985 to 2019. Genomic and peptidomic studies accelerated the discovery pace and underscored the necessity in establishing criteria for peptide entry into the APD. A total of 99.9% of the anuran antimicrobial peptides are less than 50 amino acids with an average length of 24 and a net charge of +2.5. Interestingly, the various amphibian peptide families (e.g., temporins, brevinins, esculentins) can be connected through multiple length-dependent relationships. With an increase in length, peptide net charge increases, while the hydrophobic content decreases. In addition, glycine, leucine, lysine, and proline all show linear correlations with peptide length. These correlations improve our understanding of amphibian peptides and may be useful for prediction and design of new linear peptides with potential applications in treating infectious diseases, cancer and diabetes.
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8
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Souza BBP, Cardozo Fh JL, Murad AM, Prates MV, Coura MM, Brand GD, Barbosa EA, Bloch C. Identification and characterization of phospholipases A2 from the skin secretion of Pithecopus azureus anuran. Toxicon 2019; 167:10-19. [DOI: 10.1016/j.toxicon.2019.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/17/2019] [Accepted: 06/03/2019] [Indexed: 11/26/2022]
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9
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Agbale CM, Sarfo JK, Galyuon IK, Juliano SA, Silva GGO, Buccini DF, Cardoso MH, Torres MDT, Angeles-Boza AM, de la Fuente-Nunez C, Franco OL. Antimicrobial and Antibiofilm Activities of Helical Antimicrobial Peptide Sequences Incorporating Metal-Binding Motifs. Biochemistry 2019; 58:3802-3812. [PMID: 31448597 DOI: 10.1021/acs.biochem.9b00440] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Antimicrobial peptides (AMPs) represent alternative strategies to combat the global health problem of antibiotic resistance. However, naturally occurring AMPs are generally not sufficiently active for use as antibiotics. Optimized synthetic versions incorporating additional design principles are needed. Here, we engineered amino-terminal Cu(II) and Ni(II) (ATCUN) binding motifs, which can enhance biological function, into the native sequence of two AMPs, CM15 and citropin1.1. The incorporation of metal-binding motifs modulated the antimicrobial activity of synthetic peptides against a panel of carbapenem-resistant enterococci (CRE) bacteria, including carbapenem-resistant Klebsiella pneumoniae (KpC+) and Escherichia coli (KpC+). Activity modulation depended on the type of ATCUN variant utilized. Membrane permeability assays revealed that the in silico selected lead template, CM15, and its ATCUN analogs increased bacterial cell death. Mass spectrometry, circular dichroism, and molecular dynamics simulations indicated that coordinating ATCUN derivatives with Cu(II) ions did not increase the helical tendencies of the AMPs. CM15 ATCUN variants, when combined with Meropenem, streptomycin, or chloramphenicol, showed synergistic effects against E. coli (KpC+ 1812446) biofilms. Motif addition also reduced the hemolytic activity of the wild-type AMP and improved the survival rate of mice in a systemic infection model. The dependence of these bioactivities on the particular amino acids of the ATCUN motif highlights the possible use of size, charge, and hydrophobicity to fine-tune AMP biological function. Our data indicate that incorporating metal-binding motifs into peptide sequences leads to synthetic variants with modified biological properties. These principles may be applied to augment the activities of other peptide sequences.
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Affiliation(s)
- Caleb M Agbale
- S-INOVA Biotech, Programa de Pós-Graduação em Biotecnologia , Universidade Católica Dom Bosco , Campo Grande , Mato Grosso Do Sul, MS 79117-900 , Brazil.,Department of Biochemistry, School of Biological Sciences, College of Agriculture and Natural Sciences , University of Cape Coast , Cape Coast , Ghana.,Department of Molecular Biology and Biotechnology, School of Biological Sciences, College of Agriculture and Natural Sciences , University of Cape Coast , Cape Coast , Ghana
| | - Justice K Sarfo
- S-INOVA Biotech, Programa de Pós-Graduação em Biotecnologia , Universidade Católica Dom Bosco , Campo Grande , Mato Grosso Do Sul, MS 79117-900 , Brazil
| | - Isaac K Galyuon
- Department of Molecular Biology and Biotechnology, School of Biological Sciences, College of Agriculture and Natural Sciences , University of Cape Coast , Cape Coast , Ghana
| | - Samuel A Juliano
- Department of Chemistry , University of Connecticut , Storrs , Connecticut 06269 , United States
| | - Gislaine G O Silva
- S-INOVA Biotech, Programa de Pós-Graduação em Biotecnologia , Universidade Católica Dom Bosco , Campo Grande , Mato Grosso Do Sul, MS 79117-900 , Brazil
| | - Danieli F Buccini
- S-INOVA Biotech, Programa de Pós-Graduação em Biotecnologia , Universidade Católica Dom Bosco , Campo Grande , Mato Grosso Do Sul, MS 79117-900 , Brazil
| | - Marlon H Cardoso
- S-INOVA Biotech, Programa de Pós-Graduação em Biotecnologia , Universidade Católica Dom Bosco , Campo Grande , Mato Grosso Do Sul, MS 79117-900 , Brazil.,Centro de Análises de Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia , Universidade Católica de Brasília , Brasília , DF 70790-160 , Brazil.,Programa de Pós-Graduação em Patologia Molecular, Faculdade de Medicina , Universidade de Brasília , Brasília , DF 70910-900 , Brazil
| | - Marcelo D T Torres
- Machine Biology Group, Departments of Psychiatry and Microbiology, Perelman School of Medicine, and Department of Bioengineering , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Alfredo M Angeles-Boza
- Department of Chemistry , University of Connecticut , Storrs , Connecticut 06269 , United States.,Institute of Materials Science , University of Connecticut , Storrs , Connecticut 06269 , United States
| | - Cesar de la Fuente-Nunez
- Machine Biology Group, Departments of Psychiatry and Microbiology, Perelman School of Medicine, and Department of Bioengineering , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Octavio L Franco
- S-INOVA Biotech, Programa de Pós-Graduação em Biotecnologia , Universidade Católica Dom Bosco , Campo Grande , Mato Grosso Do Sul, MS 79117-900 , Brazil.,Centro de Análises de Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia , Universidade Católica de Brasília , Brasília , DF 70790-160 , Brazil.,Programa de Pós-Graduação em Patologia Molecular, Faculdade de Medicina , Universidade de Brasília , Brasília , DF 70910-900 , Brazil
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10
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Sikora K, Jaśkiewicz M, Neubauer D, Bauer M, Bartoszewska S, Barańska-Rybak W, Kamysz W. Counter-ion effect on antistaphylococcal activity and cytotoxicity of selected antimicrobial peptides. Amino Acids 2018; 50:609-619. [PMID: 29307075 PMCID: PMC5917001 DOI: 10.1007/s00726-017-2536-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 12/28/2017] [Indexed: 12/13/2022]
Abstract
In view of an appreciable increase in resistance of Staphylococcus aureus to the conventional antibiotics, it is desired to develop new effective drugs. Antimicrobial peptides (AMPs) seem to be attractive candidates. In general, AMPs samples used for in vitro studies consist of a peptide, counter-ion, and water. The presence of the counter-ion could be significant as it affects peptide secondary structure and biological activity. The purpose of this study was to estimate the impact of counter-ion on antistaphylococcal activity of selected AMPs (CAMEL, citropin 1.1, LL-37, pexiganan, temporin A). To do this, three kinds of salts were prepared, namely, acetates, hydrochlorides, and trifluoroacetates. In addition, the hemolytic activity against human red blood cells (hRBCs) and cytotoxicity (HaCaT) were determined. The results indicate that there is a substantial difference between different salts, but the pattern is not consistent for the peptides. In general, the antistaphylococcal activity decreased in the order: CAMEL > temporin A > pexiganan > citropin 1.1 ≫ LL-37. The highest selectivity indexes were determined for CAMEL hydrochloride, pexiganan acetate, and temporin A trifluoroacetate. This study shows how important is to take into account the kind of counter-ions when designing novel peptide-based antimicrobials.
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Affiliation(s)
- Karol Sikora
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland.
| | - Maciej Jaśkiewicz
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Damian Neubauer
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Marta Bauer
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Sylwia Bartoszewska
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Wioletta Barańska-Rybak
- Chair and Clinic of Dermatology, Venereology and Allergology, Medical University of Gdańsk, Gdańsk, Poland
| | - Wojciech Kamysz
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
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11
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Cardoso MH, Oshiro KG, Rezende SB, Cândido ES, Franco OL. The Structure/Function Relationship in Antimicrobial Peptides: What Can we Obtain From Structural Data? THERAPEUTIC PROTEINS AND PEPTIDES 2018; 112:359-384. [DOI: 10.1016/bs.apcsb.2018.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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12
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Lee MR, Raman N, Gellman SH, Lynn DM, Palecek SP. Incorporation of β-Amino Acids Enhances the Antifungal Activity and Selectivity of the Helical Antimicrobial Peptide Aurein 1.2. ACS Chem Biol 2017; 12:2975-2980. [PMID: 29091404 DOI: 10.1021/acschembio.7b00843] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Antimicrobial peptides (AMPs) are attractive antifungal drug candidates because they kill microbes via membrane disruption and are thus unlikely to provoke development of resistance. Low selectivity for fungal vs human cells and instability in physiological environments have limited the development of AMPs as therapeutics, but peptidomimetic AMPs can overcome these obstacles and also provide useful insight into AMP structure-function relationships. Here, we describe antifungal peptidomimetic α/β-peptides templated on the natural α-peptidic AMP aurein 1.2. These α/β-aurein analogs fold into i → i + 4 H-bonded helices that present arrays of side chain functionality in a manner virtually identical to that of aurein 1.2. By varying charge, hydrophobicity, conformational stability, and α/β-amino acid organization, we designed active and selective α/β-peptide aurein analogs that exhibit minimum inhibitory concentrations (MIC) against the opportunistic pathogen Candida albicans that are 4-fold lower than that of aurein 1.2 and elicit less than 5% hemolysis at the MIC. These α/β-aurein analogs are promising candidates for development as antifungal therapeutics and as tools to elucidate mechanisms of AMP activity and specificity.
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Affiliation(s)
- Myung-Ryul Lee
- Department
of Chemical and Biological Engineering and ‡Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Namrata Raman
- Department
of Chemical and Biological Engineering and ‡Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Samuel H. Gellman
- Department
of Chemical and Biological Engineering and ‡Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - David M. Lynn
- Department
of Chemical and Biological Engineering and ‡Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Sean P. Palecek
- Department
of Chemical and Biological Engineering and ‡Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
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13
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Sani MA, Separovic F. Antimicrobial Peptide Structures: From Model Membranes to Live Cells. Chemistry 2017; 24:286-291. [PMID: 29068097 DOI: 10.1002/chem.201704362] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Indexed: 01/12/2023]
Abstract
The rise in antibiotic resistance has led to a renewed interest in antimicrobial peptides (AMPs) that target membranes. The mode of action of AMPs involves the disruption of the lipid bilayer and leads to growth inhibition and death of the bacteria. However, details at the molecular level of how these peptides kill bacteria and the reasons for the observed differences in selectivity remain unclear. Structural information is crucial for defining the molecular mechanism by which these peptides recognize, self-assemble and interact with a particular lipid membrane. Solid-state NMR is a non-invasive technique that allows the study of the structural details of lipid-peptide and peptide-peptide interactions. Following on from studies of antibiotic and lytic peptides, gramicidin A and melittin, respectively, we investigated maculatin 1.1, an AMP from the skin of Australian tree frogs that acts against Gram-positive bacteria. By using perdeuterated phospholipids and specifically labelled peptides, 2 H, 31 P and {31 P}15 N REDOR solid-state NMR experiments have been used to localize, maculatin 1.1 in neutral and anionic model membranes. However, the structure, location and activity depend on the composition of the model membrane and current advances in solid-state NMR spectroscopy now allow structure determination of AMPs in live bacteria.
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Affiliation(s)
- Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
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14
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Booth V, Warschawski DE, Santisteban NP, Laadhari M, Marcotte I. Recent progress on the application of 2H solid-state NMR to probe the interaction of antimicrobial peptides with intact bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1500-1511. [PMID: 28844739 DOI: 10.1016/j.bbapap.2017.07.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 07/13/2017] [Accepted: 07/25/2017] [Indexed: 10/19/2022]
Abstract
Discoveries relating to innate immunity and antimicrobial peptides (AMPs) granted Bruce Beutler and Jules Hoffmann a Nobel prize in medicine in 2011, and opened up new avenues for the development of therapies against infections, and even cancers. The mechanisms by which AMPs interact with, and ultimately disrupt, bacterial cell membranes is still, to a large extent, incompletely understood. Up until recently, this mechanism was studied using model lipid membranes that failed to reproduce the complexity of molecular interactions present in real cells comprising lipids but also membrane proteins, a cell wall containing peptidoglycan or lipopolysaccharides, and other molecules. In this review, we focus on recent attempts to study, at the molecular level, the interaction between cationic AMPs and intact bacteria, by 2H solid-state NMR. Specifically-labeled lipids allow us to focus on the interaction of AMPs with the heart of the bacterial membrane, and measure the lipid order and its variation upon interaction with various peptides. We will review the important parameters to consider in such a study, and summarize the results obtained in the past 5years on various peptides, in particular aurein 1.2, caerin 1.1, MSI-78 and CA(1-8)M(1-10). This article is part of a Special Issue entitled: Biophysics in Canada, edited by Lewis Kay, John Baenziger, Albert Berghuis and Peter Tieleman.
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Affiliation(s)
- Valerie Booth
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada; Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada
| | - Dror E Warschawski
- UMR 7099, CNRS - Université Paris Diderot, IBPC, 13 rue Pierre et Marie Curie, F-75005 Paris, France; Department of Chemistry, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montréal H3C 3P8, Canada
| | - Nury P Santisteban
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada
| | - Marwa Laadhari
- Department of Chemistry, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montréal H3C 3P8, Canada
| | - Isabelle Marcotte
- Department of Chemistry, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montréal H3C 3P8, Canada.
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15
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Retro analog concept: comparative study on physico-chemical and biological properties of selected antimicrobial peptides. Amino Acids 2017; 49:1755-1771. [PMID: 28756544 PMCID: PMC5602100 DOI: 10.1007/s00726-017-2473-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 07/20/2017] [Indexed: 01/03/2023]
Abstract
Increasing drug resistance of common pathogens urgently needs discovery of new effective molecules. Antimicrobial peptides are believed to be one of the possible solutions of this problem. One of the approaches for improvement of biological properties is reversion of the sequence (retro analog concept). This research is based on investigation of antimicrobial activity against Gram-positive, Gram-negative bacteria, and fungi, hemolysis of erythrocytes, interpretation of the circular dichroism spectra, measurement of counter-ion content, and assessment of the peptide hydrophobicity and self-assembly using reversed-phase chromatography. The experiments were conducted using the following peptides: aurein 1.2, CAMEL, citropin 1.1, omiganan, pexiganan, temporin A, and their retro analogs. Among the compounds studied, only retro omiganan showed an enhanced antimicrobial and a slightly increased hemolytic activity as compared to parent molecule. Moreover, retro pexiganan exhibited high activity towards Klebsiella pneumoniae, whereas pexiganan was in general more or equally active against the rest of tested microorganisms. Furthermore, the determined activity was closely related to the peptide hydrophobicity. In general, the reduced hemolytic activity correlates with lower antimicrobial activity. The tendency to self-association and helicity fraction in SDS seems to be correlated. The normalized RP-HPLC—temperature profiles of citropin 1.1 and aurein 1.2, revealed an enhanced tendency to self-association than that of their retro analogs.
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16
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Maciejewska M, Bauer M, Neubauer D, Kamysz W, Dawgul M. Influence of Amphibian Antimicrobial Peptides and Short Lipopeptides on Bacterial Biofilms Formed on Contact Lenses. MATERIALS 2016; 9:ma9110873. [PMID: 28773992 PMCID: PMC5457276 DOI: 10.3390/ma9110873] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/22/2016] [Accepted: 10/20/2016] [Indexed: 12/28/2022]
Abstract
The widespread use of contact lenses is associated with several complications, including ocular biofilm-related infections. They are very difficult to manage with standard antimicrobial therapies, because bacterial growth in a biofilm is associated with an increased antibiotic resistance. The principal aim of this study was to evaluate the efficacy of antimicrobial peptides (AMPs) in eradication of bacterial biofilms formed on commercially available contact lenses. AMPs were synthesized according to Fmoc/tBu chemistry using the solid-phase method. Minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of the compounds were determined. Anti-biofilm activity of the antimicrobial peptides determined at different temperatures (25 °C and 37 °C) were compared with the effectiveness of commercially available contact lens solutions. All of the tested compounds exhibited stronger anti-biofilm properties as compared to those of the tested lens solutions. The strongest activity of AMPs was noticed against Gram-positive strains at a temperature of 25 °C. Conclusions: The results of our experiments encourage us toward further studies on AMPs and their potential application in the prophylaxis of contact lens-related eye infections.
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Affiliation(s)
- Magdalena Maciejewska
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk 80-416, Poland.
- Pharmaceutical Laboratory, Avena SJ, Osielsko 86-031, Poland.
| | - Marta Bauer
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk 80-416, Poland.
| | - Damian Neubauer
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk 80-416, Poland.
| | - Wojciech Kamysz
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk 80-416, Poland.
| | - Malgorzata Dawgul
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk 80-416, Poland.
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17
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Abstract
The structure-function relationship for a family of antimicrobial peptides (AMPs) from the skin of Australian tree frogs is discussed and compared with that of peptide toxins from bee and Australian scorpion venoms. Although these membrane-active peptides induce a similar cellular fate by disrupting the lipid bilayer integrity, their lytic activity is achieved via different modes of action, which are investigated in relation to amino acid sequence, secondary structure, and membrane lipid composition. In order to better understand what structural features govern the interaction between peptides and lipid membranes, cell-penetrating peptides (CPPs), which translocate through the membrane without compromising its integrity, are also discussed. AMPs possess membrane lytic activities that are naturally designed to target the cellular membrane of pathogens or competitors. They are extremely diverse in amino acid composition and often show specificity against a particular strain of microbe. Since our antibiotic arsenal is declining precariously in the face of the rise in multiantibiotic resistance, AMPs increasingly are seen as a promising alternative. In an effort to understand their molecular mechanism, biophysical studies of a myriad of AMPs have been reported, yet no unifying mechanism has emerged, rendering difficult the rational design of drug leads. Similarly, a wide variety of cytotoxic peptides are found in venoms, the best known being melittin, yet again, predicting their activity based on a particular amino acid composition or secondary structure remains elusive. A common feature of these membrane-active peptides is their preference for the lipid environment. Indeed, they are mainly unstructured in solution and, in the presence of lipid membranes, quickly adsorb onto the surface, change their secondary structure, eventually insert into the hydrophobic core of the membrane bilayer, and finally disrupt the bilayer integrity. These steps define the molecular mechanism by which these membrane-active peptides lyse membranes. The last class of membrane-active peptides discussed are the CPPs, which translocate across the lipid bilayer without inducing severe disruption and have potential as drug vehicles. CPPs are typically highly charged and can show antimicrobial activity by targeting an intracellular target rather than via a direct membrane lytic mechanism. A critical aspect in the structure-function relationship of membrane-active peptides is their specific activity relative to the lipid membrane composition of the cell target. Cell membranes have a wide diversity of lipids, and those of eukaryotic and prokaryotic species differ greatly in composition and structure. The activity of AMPs from Australian tree frogs, toxins, and CPPs has been investigated within various lipid systems to assess whether a relationship between peptide and membrane composition could be identified. NMR spectroscopy techniques are being used to gain atomistic details of how these membrane-active peptides interact with model membranes and cells, and in particular, competitive assays demonstrate the difference between affinity and activity for a specific lipid environment. Overall, the interactions between these relatively small sized peptides and various lipid bilayers give insight into how these peptides function at the membrane interface.
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Affiliation(s)
- Marc-Antoine Sani
- School of Chemistry, Bio21
Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Frances Separovic
- School of Chemistry, Bio21
Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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18
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Li M, Tao Y, Shu Y, LaRochelle JR, Steinauer A, Thompson D, Schepartz A, Chen ZY, Liu DR. Discovery and Characterization of a Peptide That Enhances Endosomal Escape of Delivered Proteins in Vitro and in Vivo. J Am Chem Soc 2015; 137:14084-93. [DOI: 10.1021/jacs.5b05694] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Margie Li
- Department of Chemistry & Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Yong Tao
- Department
of Otolaryngology and Program in Neuroscience, Harvard Medical School and Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, United States
| | - Yilai Shu
- Department
of Otolaryngology and Program in Neuroscience, Harvard Medical School and Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, United States
- Department
of Otology and Skull Base Survery, Eye, Ear, Nose and Throat Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China
- Key
Laboratory of Hearing Medicine, Ministry of Health, Shanghai, 200031, China
| | - Jonathan R. LaRochelle
- Department
of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Angela Steinauer
- Department
of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - David Thompson
- Department of Chemistry & Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Alanna Schepartz
- Department
of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8107, United States
- Department
of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Zheng-Yi Chen
- Department
of Otolaryngology and Program in Neuroscience, Harvard Medical School and Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, United States
| | - David R. Liu
- Department of Chemistry & Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
- Howard
Hughes Medical Institute, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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19
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Carbohydrate scaffolds as glycosyltransferase inhibitors with in vivo antibacterial activity. Nat Commun 2015; 6:7719. [PMID: 26194781 PMCID: PMC4530474 DOI: 10.1038/ncomms8719] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 06/05/2015] [Indexed: 02/08/2023] Open
Abstract
The rapid rise of multi-drug-resistant bacteria is a global healthcare crisis, and new antibiotics are urgently required, especially those with modes of action that have low-resistance potential. One promising lead is the liposaccharide antibiotic moenomycin that inhibits bacterial glycosyltransferases, which are essential for peptidoglycan polymerization, while displaying a low rate of resistance. Unfortunately, the lipophilicity of moenomycin leads to unfavourable pharmacokinetic properties that render it unsuitable for systemic administration. In this study, we show that using moenomycin and other glycosyltransferase inhibitors as templates, we were able to synthesize compound libraries based on novel pyranose scaffold chemistry, with moenomycin-like activity, but with improved drug-like properties. The novel compounds exhibit in vitro inhibition comparable to moenomycin, with low toxicity and good efficacy in several in vivo models of infection. This approach based on non-planar carbohydrate scaffolds provides a new opportunity to develop new antibiotics with low propensity for resistance induction.
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20
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Xu X, Lai R. The chemistry and biological activities of peptides from amphibian skin secretions. Chem Rev 2015; 115:1760-846. [PMID: 25594509 DOI: 10.1021/cr4006704] [Citation(s) in RCA: 220] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Xueqing Xu
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology , Kunming 650223, Yunnan, China
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21
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König E, Bininda-Emonds ORP, Shaw C. The diversity and evolution of anuran skin peptides. Peptides 2015; 63:96-117. [PMID: 25464160 DOI: 10.1016/j.peptides.2014.11.003] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 02/06/2023]
Abstract
Amphibians exhibit various, characteristic adaptations related to their "incomplete" shift from the aquatic to the terrestrial habitat. In particular, the integument was subject to a number of specialized modifications during the evolution of these animals. In this review, we place special emphasis on endogenous host-defence skin peptides from the cuteanous granular glands anuran amphibians (frogs and toads). The overview on the two broad groups of neuroactive and antimicrobial peptides (AMPs) goes beyond a simple itemization in that we provide a new perspective into the evolution and function of anuran AMPs. Briefly, these cationic, amphipathic and α-helical peptides are traditionally viewed as being part of the innate immune system, protecting the moist skin against invading microorganisms through their cytolytic action. However, the complete record of anuran species investigated to date suggests that AMPs are distributed sporadically (i.e., non-universally) across Anura. Together with the intriguing observation that virtually all anurans known to produce neuropeptides in their granular glands also co-secrete cytolytic peptides, we call the traditional role for AMPs as being purely antimicrobial into question and present an alternative scenario. We hypothesize AMPs to assist neuroactive peptides in their antipredator role through their cytolytic action increasing the delivery of the latter to the endocrine and nervous system of the predator. Thus, AMPs are more accurately viewed as cytolysins and their contribution to the immune system is better regarded as an accessory benefit.
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Affiliation(s)
- Enrico König
- AG Systematik und Evolutionsbiologie, IBU - Fakultät V, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky Strasse 9-11, 26129 Oldenburg, Germany.
| | - Olaf R P Bininda-Emonds
- AG Systematik und Evolutionsbiologie, IBU - Fakultät V, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky Strasse 9-11, 26129 Oldenburg, Germany
| | - Chris Shaw
- School of Pharmacy, Medical Biology Center, Queen's University, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
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22
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Praporski S, Mechler A, Separovic F, Martin LL. Subtle Differences in Initial Membrane Interactions Underpin the Selectivity of Small Antimicrobial Peptides. Chempluschem 2014. [DOI: 10.1002/cplu.201402318] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Slavica Praporski
- School of Chemistry, Monash University, Clayton, VIC 3800 (Australia)
- Current address: Heart Research, Murdoch Childrens Research Institute, Parkville, VIC 3052 (Australia)
| | - Adam Mechler
- School of Chemistry, Monash University, Clayton, VIC 3800 (Australia)
- Current address: School of Molecular Sciences, La Trobe University, Bundoora, VIC 3086 (Australia)
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC 3010 (Australia)
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23
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Uggerhøj LE, Poulsen TJ, Munk JK, Fredborg M, Sondergaard TE, Frimodt-Moller N, Hansen PR, Wimmer R. Rational Design of Alpha-Helical Antimicrobial Peptides: Do's and Don'ts. Chembiochem 2014; 16:242-53. [DOI: 10.1002/cbic.201402581] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Indexed: 11/06/2022]
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24
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Comparison of reversible membrane destabilisation induced by antimicrobial peptides derived from Australian frogs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2205-15. [PMID: 24593995 DOI: 10.1016/j.bbamem.2014.02.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/21/2014] [Accepted: 02/21/2014] [Indexed: 12/28/2022]
Abstract
The membrane destabilising properties of the antimicrobial peptides (AMP) aurein 1.2, citropin 1.1, maculatin 1.1 and caerin 1.1, have been studied by dual polarisation interferometry (DPI). The overall process of peptide induced membrane destabilisation was examined by the changes in bilayer order as a function of membrane-bound peptide mass per unit area and revealed three different modes of action. Aurein 1.2 was the only peptide that significantly destabilised the neutral membrane (DMPC), while all four peptides induced destabilisation of the negatively charged membrane (DMPC/DMPG). On DMPC, citropin 1.1, maculatin 1.1 and caerin 1.1 bound irreversibly at low concentrations but caused a reversible drop in the bilayer order. In contrast to DMPC/DMPG, these three peptides caused a mass drop at the higher concentrations, which may correspond to insertion and bilayer expansion. The critical level of bound peptide necessary to induce membrane destabilisation (peptide:lipid ratio) was determined and correlated with peptide structure. As the most lytic peptide, aurein 1.2 adsorbed strongly prior to dissolution of the bilayer. In contrast, the binding of citropin 1.1, maculatin 1.1 and caerin 1.1 needed to reach a critical level prior to insertion into the membrane and incremental expansion and disruption. Our results demonstrate that sequential events can be monitored in real-time under fluidic conditions to elucidate the complex molecular mechanism of AMP action. In particular, the analysis of birefringence in real time allows the description of a detailed mechanistic model of the impact of peptides on the membrane bilayer order. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.
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25
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Ribosomally synthesized peptides from natural sources. J Antibiot (Tokyo) 2014; 67:277-89. [DOI: 10.1038/ja.2013.138] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 10/07/2013] [Accepted: 11/25/2013] [Indexed: 01/28/2023]
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26
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Robertson LS, Fellers GM, Marranca JM, Kleeman PM. Expression analysis and identification of antimicrobial peptide transcripts from six North American frog species. DISEASES OF AQUATIC ORGANISMS 2013; 104:225-236. [PMID: 23759560 DOI: 10.3354/dao02601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Frogs secrete antimicrobial peptides onto their skin. We describe an assay to preserve and analyze antimicrobial peptide transcripts from field-collected skin secretions that will complement existing methods for peptide analysis. We collected skin secretions from 4 North American species in the field in California and 2 species in the laboratory. Most frogs appeared healthy after release; however, Rana boylii in the Sierra Nevada foothills, but not the Coast Range, showed signs of morbidity and 2 died after handling. The amount of total RNA extracted from skin secretions was higher in R. boylii and R. sierrae compared to R. draytonii, and much higher compared to Pseudacris regilla. Interspecies variation in amount of RNA extracted was not explained by size, but for P. regilla it depended upon collection site and date. RNA extracted from skin secretions from frogs handled with bare hands had poor quality compared to frogs handled with gloves or plastic bags. Thirty-four putative antimicrobial peptide precursor transcripts were identified. This study demonstrates that RNA extracted from skin secretions collected in the field is of high quality suitable for use in sequencing or quantitative PCR (qPCR). However, some species do not secrete profusely, resulting in very little extracted RNA. The ability to measure transcript abundance of antimicrobial peptides in field-collected skin secretions complements proteomic analyses and may provide insight into transcriptional mechanisms that could affect peptide abundance.
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27
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Calabrese AN, Markulic K, Musgrave IF, Guo H, Zhang L, Bowie JH. Structural and activity changes in three bioactive anuran peptides when Asp is replaced by isoAsp. Peptides 2012; 38:427-36. [PMID: 23069634 DOI: 10.1016/j.peptides.2012.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 10/04/2012] [Accepted: 10/04/2012] [Indexed: 12/12/2022]
Abstract
The Asp and isoAsp isomers of three bioactive peptides, Crinia angiotensin 11 [APGDRIYHPF(OH)], uperin 1.1 [pEADPNAFYGLM(NH(2))] and citropin 1.1 [GLFDVIKKVASVIGGL(NH(2))] were tested for changes in (i) susceptibility towards proteolytic cleavage, (ii) activity (smooth muscle activity for Crinia angiotensin 11 and uperin 1.1 isomers, and antimicrobial activity for the two isomers of citropin 1.1), and (iii) 3D structures in water, trifluoroethanol-d(3)/water (1:1) and DPC micelles as determined by 2D nuclear magnetic resonance spectroscopy. Proteolytic cleavage with trypsin was identical for each pair of Asp/isoAsp isomers. Cleavage with chymotrypsin was the same for the Crinia angiotensin and uperin 1.1 isomeric pairs, but different for the two Asp/isoAsp citropin 1.1 isomers. Chymotrypsin cleaved at Phe3 (adjacent to Asp4) for citropin 1.1, but not at Phe3 (adjacent to isoAsp4) for isoAsp citropin 1.1. The smooth muscle activity of the isoAsp isomer of Crinia angiotensin 11 was less than that of the Asp isomer. The smooth muscle activity of isoAsp3-uperin 1.1 is greater than that of the Asp isomer at low concentration (<10(-9)M) but no different from the Asp isomer at concentrations>10(-9) M. Citropin 1.1 is a wide-spectrum antibiotic against Gram positive organisms, while the isoAsp isomer is inactive against the test pathogens Staphylococcus aureus and Bacillus subtilis. The observed changes in activity are accompanied by changes in the 3D structures of isomers as determined by 2D nuclear magnetic resonance spectroscopy.
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Affiliation(s)
- Antonio N Calabrese
- Department of Chemistry, School of Chemistry and Physics, The University of Adelaide, South Australia 5005, Australia
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28
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Bowie JH, Separovic F, Tyler MJ. Host-defense peptides of Australian anurans. Part 2. Structure, activity, mechanism of action, and evolutionary significance. Peptides 2012; 37:174-88. [PMID: 22771617 DOI: 10.1016/j.peptides.2012.06.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 06/26/2012] [Accepted: 06/26/2012] [Indexed: 01/01/2023]
Abstract
A previous review summarized research prior to 2004 carried out on the bioactive host-defense peptides contained in the skin secretions of Australian anurans (frogs and toads). This review covers the extension of that research from 2004 to 2012, and includes membrane-active peptides (including antibacterial, anticancer, antifungal and antiviral peptides) together with the mechanisms by which these peptides interact with model membranes, peptides that may be classified as "neuropeptides" (including smooth muscle active peptides, opioids and immunomodulators) and peptides which inhibit the formation of nitric oxide from neuronal nitric oxide synthase. The review discusses the outcome of cDNA sequencing of signal-spacer-active peptides from an evolutionary viewpoint, and also lists those peptides for which activities have not been found to this time.
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Affiliation(s)
- John H Bowie
- Department of Chemistry, School of Chemistry and Physics, The University of Adelaide, South Australia 5005, Australia.
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29
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Chia CSB, Gong Y, Bowie JH, Zuegg J, Cooper MA. Membrane binding and perturbation studies of the antimicrobial peptides caerin, citropin, and maculatin. Biopolymers 2011; 96:147-57. [PMID: 20564028 DOI: 10.1002/bip.21438] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Citropin 1.1, maculatin 1.1, and caerin 1.1 are short antibacterial cationic peptides from the skin glands of the Australian tree frog Litoria species. Several analogues have been synthesized to give a better insight into the relationship between the structure of the peptides and their antibacterial and haemolytic activity. Binding studies using a surface plasmon resonance (SPR) biosensor together with a vesicle-capture sensor chip have been used to investigate selectivity of the peptides and their analogues for 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) vesicles, as well as for vesicles made from lipid extracts from Escherichia coli and bovine brain. Data obtained for membrane selectivity using natural lipid extracts show better correlation with minimum inhibitory concentration (MIC) values against Gram-positive bacteria and haemolytic activity than that obtained using synthetic DMPG and DMPC. Electron microscopy and membrane leakage studies using Gram-positive bacteria gave further insight into the membrane disruption properties of the peptides. For maculatin 1.1, it was found that the central proline residue, which is responsible for a bend in the alpha-helical structure, is essential not only for the antibacterial activity but also for binding, and perturbation of membranes. The caerin analogues showed only small variations in their MIC values and membrane binding. In contrast, for citropin 1.1, the analogue replacing the aspartate with a lysine showed the lowest MIC against Gram-positive bacteria and best membrane binding to E. coli lipid extracts, coinciding with an increased hydrophobic moment of the peptide. These data give further insight into these antimicrobial natural products, toward the development and evaluation of these and other analogues as potential antibiotics.
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Affiliation(s)
- C S Brian Chia
- Experimental Therapeutics Centre, Agency for Science, Technology and Research, 31 Biopolis Way, #03-01 Nanos, 138669, Singapore
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Abstract
AbstractIncreased prevalence of multi-drug resistance in pathogens has encouraged researchers to focus on finding novel forms of anti-infective agents. Antimicrobial peptides (AMPs) found in animal secretions are components of host innate immune response and have survived eons of pathogen evolution. Thus, they are likely to be active against pathogens and even those that are resistant to conventional drugs. Many peptides have been isolated and shown to be effective against multi-drug resistant pathogens. More than 500 AMPs have been identified from amphibians. The abundance of AMPs in frog skin is remarkable and constitutes a rich source for design of novel pharmaceutical molecules. Expression and post-translational modifications, discovery, activities and probable therapeutic application prospects of amphibian AMPs will be discussed in this article.
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Affiliation(s)
- Yao Xiao
- 1Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan, China
| | - Cunbao Liu
- 1Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan, China
| | - Ren Lai
- 1Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan, China
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Chen R, Mark AE. The effect of membrane curvature on the conformation of antimicrobial peptides: implications for binding and the mechanism of action. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2011; 40:545-53. [PMID: 21267557 PMCID: PMC3070085 DOI: 10.1007/s00249-011-0677-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 12/06/2010] [Accepted: 01/11/2011] [Indexed: 01/20/2023]
Abstract
Short cationic antimicrobial peptides (AMPs) are believed to act either by inducing transmembrane pores or disrupting membranes in a detergent-like manner. For example, the antimicrobial peptides aurein 1.2, citropin 1.1, maculatin 1.1 and caerin 1.1, despite being closely related, appear to act by fundamentally different mechanisms depending on their length. Using molecular dynamics simulations, the structural properties of these four peptides have been examined in solution as well as in a variety of membrane environments. It is shown that each of the peptides has a strong preference for binding to regions of high membrane curvature and that the structure of the peptides is dependent on the degree of local curvature. This suggests that the shorter peptides aurein 1.2 and citropin 1.1 act via a detergent-like mechanism because they can induce high local, but not long-range curvature, whereas the longer peptides maculatin 1.1 and caerin 1.1 require longer range curvature to fold and thus bind to and stabilize transmembrane pores.
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Affiliation(s)
- Rong Chen
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Alan E. Mark
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072 Australia
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Importance of residue 13 and the C-terminus for the structure and activity of the antimicrobial peptide aurein 2.2. Biophys J 2011; 99:2926-35. [PMID: 21044590 DOI: 10.1016/j.bpj.2010.08.077] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 08/24/2010] [Accepted: 08/30/2010] [Indexed: 11/22/2022] Open
Abstract
Previous studies on aurein 2.2 and 2.3 in DMPC/DMPG and POPC/POPG membranes have shown that bilayer thickness and phosphatidylglycerol content have a significant impact on the interaction of these peptides with membrane bilayers. Further examination with the DiSC(3)5 assay has indicated that aurein 2.2 induces greater membrane leakage than aurein 2.3 in Staphylococcus aureus C622. The only difference between these peptides is a Leu to Ile mutation at residue 13. To better understand the importance of this residue, the structure and activity of the L13A, L13F, and L13V mutants were investigated. In addition, we investigated a number of peptides with truncations at the C-terminus to determine whether the C-terminus, which contains residue 13, is crucial for antimicrobial activity. Solution circular dichroism results demonstrated that the L13F mutation and the truncation of the C-terminus by six residues resulted in decreased helical content, whereas the L13A or L13V mutation and the truncation of the C-terminus by three residues showed little to no effect on the structure. Oriented circular dichroism results demonstrated that only an extensive C-terminal truncation reduced the ability of the peptide to insert into lipid bilayers. (31)P NMR spectroscopy showed that all peptides disorder the headgroups. The implications of these results in terms of antimicrobial activity and the ability of these peptides to induce leakage in S. aureus are discussed. The results suggest that the presence of the 13th residue in aurein 2.2 is important for structure and activity, but the exact nature of residue 13 is less important as long as it is a hydrophobic residue.
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Abstract
Many bioactive peptides are featured by their unique amino acid compositions such as argine/lysine-rich peptides. However, histidine-rich bioactive peptides are hardly found. In this study, histidine-containing peptides were constructed by selectively replacing the corresponded lysine residues in a lytic peptide LL-1 with histidines. Interestingly, all resulting peptides demonstrated pH-dependent activities. The cell lysis activities of these peptides could be increased up to four times as the solution pHs dropped from pH = 7.4 to pH = 5.5. The pH sensitivity of a histidine-containing peptide was determined by histidine substitution numbers. Peptide derivatives with more histidines were associated with increased pH sensitivity. Results showed that not the secondary structures but pH-affected cell affinity changes were responsible for the pH-dependent activities of histidine-containing peptides. The histidine substitution approach demonstrated here may present a general strategy to construct bioactive peptides with desired pH sensitivity for various applications.
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Affiliation(s)
- Zhigang Tu
- Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
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Sherman PJ, Jackway RJ, Gehman JD, Praporski S, McCubbin GA, Mechler A, Martin LL, Separovic F, Bowie JH. Solution Structure and Membrane Interactions of the Antimicrobial Peptide Fallaxidin 4.1a: An NMR and QCM Study. Biochemistry 2009; 48:11892-901. [DOI: 10.1021/bi901668y] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Patrick J. Sherman
- Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
| | - Rebecca J. Jackway
- Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
| | - John D. Gehman
- School of Chemistry, Bio21 Institute, University of Melbourne, Victoria 3010, Australia
| | | | | | - Adam Mechler
- School of Chemistry, Monash University, Victoria 3800, Australia
| | | | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Victoria 3010, Australia
| | - John H. Bowie
- Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
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Tu Z, Volk M, Shah K, Clerkin K, Liang JF. Constructing bioactive peptides with pH-dependent activities. Peptides 2009; 30:1523-8. [PMID: 19464332 PMCID: PMC2735074 DOI: 10.1016/j.peptides.2009.05.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 05/06/2009] [Accepted: 05/11/2009] [Indexed: 10/20/2022]
Abstract
Many bioactive peptides are featured by their arginine and lysine rich contents. In this study, lysine and arginine residues in lytic peptides were selectively replaced by histidines. Although resulting histidine-containing lytic peptides had decreased activity, they did show pH-dependent cytotoxicity. The activity of the constructed histidine-containing lytic peptides increased 2-8 times as the solution pH changed from 7.4 to 5.5. More importantly, these histidine-containing peptides maintain the same cell killing mechanism as their parent peptides by causing cell lysis. Both the activity and pH-sensitivity of histidine-containing peptides are tunable by adjusting histidine substitution numbers and positions. This study has presented a general strategy to create bioactive peptides with desired pH-sensitivity to meet the needs of various applications such as cancer treatments.
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Affiliation(s)
| | | | | | | | - Jun F. Liang
- Corresponding Author Dr. Jun F. Liang, Department of Chemistry, Chemical Biology, and Biomedical Engineering Stevens Institute of Technology Hoboken, NJ 07030 USA Tel.: 201-216-5640; Fax: 201-216-8240 Email.:
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Sikorska E, Greber K, Rodziewicz-Motowidło S, Szultka L, Lukasiak J, Kamysz W. Synthesis and antimicrobial activity of truncated fragments and analogs of citropin 1.1: The solution structure of the SDS micelle-bound citropin-like peptides. J Struct Biol 2009; 168:250-8. [PMID: 19616100 DOI: 10.1016/j.jsb.2009.07.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 07/11/2009] [Accepted: 07/14/2009] [Indexed: 01/13/2023]
Abstract
Citropin 1.1 is a basic, highly hydrophobic, 16-amino acid peptide (GLFDVIKKVASVIGGL-NH(2)), displaying wide-spectrum antimicrobial activities. In this paper we describe the synthesis and antimicrobial properties of citropin 1.1 and its 18 analogs constituting mostly truncated fragments of citropin 1.1. Moreover, we examined conformational properties of citropin 1.1 and its two analogs, (1-12)citropin and (1-13)[Ala(4)]citropin, using FTIR, CD and NMR spectroscopies. Three-dimensional structures of the peptides were determined using molecular dynamics (MD) simulations with time-averaged (TAV) restraints obtained from NMR spectra measured in micellar concentration of sodium dodecyl sulfate (SDS). Earlier investigations showed that in TFE solution, citropin 1.1 is a single helix all along the backbone. However, this structure is not retained in the presence of SDS micelle. In H(2)O/SDS-d(25) solution, citropin 1.1 adopts two alpha-helices in the fragments 4-7 and 10-16, respectively, separated by betaIV-turn at position 8, 9. The (1-12)citropin adopts an alpha-helical structure along the entire backbone. In turn, (1-13)[Ala(4)]citropin demonstrates the tendency to adopt only a short alpha-helix in the middle part. Moreover, the conversion of alpha-helix to 3(10)-helix has been noticed in about 30% of conformations. The 3(10)-helical units could be thermodynamic intermediates during folding and unfolding of the alpha-helical segment of the peptide.
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Cheng JTJ, Hale JD, Elliot M, Hancock REW, Straus SK. Effect of membrane composition on antimicrobial peptides aurein 2.2 and 2.3 from Australian southern bell frogs. Biophys J 2009; 96:552-65. [PMID: 19167304 DOI: 10.1016/j.bpj.2008.10.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 10/09/2008] [Indexed: 12/25/2022] Open
Abstract
The effects of hydrophobic thickness and the molar phosphatidylglycerol (PG) content of lipid bilayers on the structure and membrane interaction of three cationic antimicrobial peptides were examined: aurein 2.2, aurein 2.3 (almost identical to aurein 2.2, except for a point mutation at residue 13), and a carboxy C-terminal analog of aurein 2.3. Circular dichroism results indicated that all three peptides adopt an alpha-helical structure in the presence of a 3:1 molar mixture of 1,2-dimyristoyl-sn-glycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPC/DMPG), and 1:1 and 3:1 molar mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPC/POPG). Oriented circular dichroism data for three different lipid compositions showed that all three peptides were surface-adsorbed at low peptide concentrations, but were inserted into the membrane at higher peptide concentrations. The (31)P solid-state NMR data of the three peptides in the DMPC/DMPG and POPC/POPG bilayers showed that all three peptides significantly perturbed lipid headgroups, in a peptide or lipid composition-dependent manner. Differential scanning calorimetry results demonstrated that both amidated aurein peptides perturbed the overall phase structure of DMPC/DMPG bilayers, but perturbed the POPC/POPG chains less. The nature of the perturbation of DMPC/DMPG bilayers was most likely micellization, and for the POPC/POPG bilayers, distorted toroidal pores or localized membrane aggregate formation. Calcein release assay results showed that aurein peptide-induced membrane leakage was more severe in DMPC/DMPG liposomes than in POPC/POPG liposomes, and that aurein 2.2 induced higher calcein release than aurein 2.3 and aurein 2.3-COOH from 1:1 and 3:1 POPC/POPG liposomes. Finally, DiSC(3)5 assay data further delineated aurein 2.2 from the others by showing that it perturbed the lipid membranes of intact S. aureus C622 most efficiently, whereas aurein 2.3 had the same efficiency as gramicidin S, and aurein 2.3-COOH was the least efficient. Taken together, these data show that the membrane interactions of aurein peptides are affected by the hydrophobic thickness of the lipid bilayers and the PG content.
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Affiliation(s)
- John T J Cheng
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
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Abstract
Amphibians have been found to be a source of agents with anticancer properties. Bufalin, for example, is an anticancer agent that may induce apoptosis by its interaction with other genes and cellular components. Certain peptides with anticancer activities have been found in amphibian skin; they include magainins, aureins, citropin 1.1 and gaegurins. These peptides may exert a cytotoxic effect on human cancer cells through various mechanisms. Onconase, amphinase, cSBL (sialic acid-binding lectin purified from Rana catesbeiana eggs) and jSBL (sialic acid-binding lectin purified from Rana japonica eggs), which belong to the RNase A family, were purified from the oocyte cells and eggs of three amphibians, and they induce cytotoxicity by degrading cellular RNA. This paper discusses the medical and pharmaceutical significance of products derived from amphibians.
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40
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Haney EF, Hunter HN, Matsuzaki K, Vogel HJ. Solution NMR studies of amphibian antimicrobial peptides: linking structure to function? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1639-55. [PMID: 19272309 DOI: 10.1016/j.bbamem.2009.01.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 12/19/2008] [Accepted: 01/09/2009] [Indexed: 10/21/2022]
Abstract
The high-resolution three-dimensional structure of an antimicrobial peptide has implications for the mechanism of its antimicrobial activity, as the conformation of the peptide provides insights into the intermolecular interactions that govern the binding to its biological target. For many cationic antimicrobial peptides the negatively charged membranes surrounding the bacterial cell appear to be a main target. In contrast to what has been found for other classes of antimicrobial peptides, solution NMR studies have revealed that in spite of the wide diversity in the amino acid sequences of amphibian antimicrobial peptides (AAMPs), they all adopt amphipathic alpha-helical structures in the presence of membrane-mimetic micelles, bicelles or organic solvent mixtures. In some cases the amphipathic AAMP structures are directly membrane-perturbing (e.g. magainin, aurein and the rana-box peptides), in other instances the peptide spontaneously passes through the membrane and acts on intracellular targets (e.g. buforin). Armed with a high-resolution structure, it is possible to relate the peptide structure to other relevant biophysical and biological data to elucidate a mechanism of action. While many linear AAMPs have significant antimicrobial activity of their own, mixtures of peptides sometimes have vastly improved antibiotic effects. Thus, synergy among antimicrobial peptides is an avenue of research that has recently attracted considerable attention. While synergistic relationships between AAMPs are well described, it is becoming increasingly evident that analyzing the intermolecular interactions between these peptides will be essential for understanding the increased antimicrobial effect. NMR structure determination of hybrid peptides composed of known antimicrobial peptides can shed light on these intricate synergistic relationships. In this work, we present the first NMR solution structure of a hybrid peptide composed of magainin 2 and PGLa bound to SDS and DPC micelles. The hybrid peptide adopts a largely helical conformation and some information regarding the inter-helix organization of this molecule is reported. The solution structure of the micelle associated MG2-PGLa hybrid peptide highlights the importance of examining structural contributions to the synergistic relationships but it also demonstrates the limitations in the resolution of the currently used solution NMR techniques for probing such interactions. Future studies of antimicrobial peptide synergy will likely require stable isotope-labeling strategies, similar to those used in NMR studies of proteins.
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Affiliation(s)
- Evan F Haney
- Structural Biology Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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Bilusich D, Bowie JH. Fragmentations of (M-H)- anions of underivatised peptides. Part 2: Characteristic cleavages of Ser and Cys and of disulfides and other post-translational modifications, together with some unusual internal processes. MASS SPECTROMETRY REVIEWS 2009; 28:20-34. [PMID: 18989895 DOI: 10.1002/mas.20206] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In a previous review (Bowie, Brinkworth, & Dua (2002); Mass Spectrom Rev 21:87-107) we described the characteristic backbone cleavages and side chain fragmentations which occur from (M-H)(-) parent anions of underivatized peptides. This work is briefly summarized in the present review. Cys was not described in the previous review: here we describe the Cys characteristic side chain loss of H(2)S, together with its gamma backbone cleavage. These processes are compared with those of the related Ser. All experimental observations are backed up with theoretical studies at the HF/6-31G(d)//AM1 level of theory, a level of theory which we have shown gives good geometries and acceptable relative energies. The negative ion cleavages of a number of post-translational modifications are described. Negative ion mass spectrometry is the method of choice for identification of disulfides in both peptides and proteins. Intramolecular disulfides are identified by the presence of the fragment anion [(M-H)(-)-H(2)S(2)], and CID MS2 of this fragment normally identifies the positions of the two Cys residues and often the full sequence of the peptide. An unsymmetrically substituted intermolecular disulfide can give up to eight characteristic fragment anions, and CID MS2 of some, or all of these often provides the full sequence of those peptides which form the initial intermolecular disulfide linkage. Negative ion cleavages of disulfides are the most energetically favored of all peptide negative cleavages studied to date. Negative ion mass spectrometry is also valuable for the identification of pyroglutamates, sulfates and phosphates. Finally, some unusual fragmentations are described which involve cyclization/elimination reactions which require the decomposing (M-H)(-) parent anions to adopt the same helical conformation that these peptides have in solution.
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Affiliation(s)
- Daniel Bilusich
- Department of Chemistry, The University of Adelaide, SA 5005, Australia
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42
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Pukala TL, Urathamakul T, Watt SJ, Beck JL, Jackway RJ, Bowie JH. Binding studies of nNOS-active amphibian peptides and Ca2+ calmodulin, using negative ion electrospray ionisation mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2008; 22:3501-3509. [PMID: 18853393 DOI: 10.1002/rcm.3757] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Amphibian peptides which inhibit the formation of nitric oxide by neuronal nitric oxide synthase (nNOS) do so by binding to the protein cofactor, Ca2+calmodulin (Ca2+CaM). Complex formation between active peptides and Ca2+CaM has been demonstrated by negative ion electrospray ionisation mass spectrometry using an aqueous ammonium acetate buffer system. In all cases studied, the assemblies are formed with a 1:1:4 calmodulin/peptide/Ca2+ stoichiometry. In contrast, the complex involving the 20-residue binding domain of the plasma Ca2+ pump C20W (LRRGQILWFRGLNRIQTQIK-OH) with CaM has been shown by previous two-dimensional nuclear magnetic resonance (2D NMR) studies to involve complexation of the C-terminal end of CaM. Under identical conditions to those used for the amphibian peptide study, the ESI complex between C20W and CaM shows specific 1:1:2 stoichiometry. Since complex formation with the studied amphibian peptides requires Ca2+CaM to contain its full complement of four Ca2+ ions, this indicates that the amphibian peptides require both ends of the CaM to effect complex formation. Charge-state analysis and an H/D exchange experiment (with caerin 1.8) suggest that complexation involves Ca2+CaM undergoing a conformational change to a more compact structure.
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Affiliation(s)
- Tara L Pukala
- Department of Chemistry, The University of Adelaide, South Australia, 5005, Australia
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Fernandez DI, Gehman JD, Separovic F. Membrane interactions of antimicrobial peptides from Australian frogs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:1630-8. [PMID: 19013126 DOI: 10.1016/j.bbamem.2008.10.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 10/08/2008] [Accepted: 10/12/2008] [Indexed: 10/21/2022]
Abstract
The membrane interactions of four antimicrobial peptides, aurein 1.2, citropin 1.1, maculatin 1.1 and caerin 1.1, isolated from Australian tree frogs, are reviewed. All four peptides are amphipathic alpha-helices with a net positive charge and range in length from 13 to 25 residues. Despite several similar sequence characteristics, these peptides compromise the integrity of model membrane bilayers via different mechanisms; the shorter peptides exhibit a surface interaction mechanism while the longer peptides may form pores in membranes.
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Affiliation(s)
- David I Fernandez
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne VIC 3010, Australia
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Mechler A, Praporski S, Atmuri K, Boland M, Separovic F, Martin LL. Specific and selective peptide-membrane interactions revealed using quartz crystal microbalance. Biophys J 2007; 93:3907-16. [PMID: 17704161 PMCID: PMC2084233 DOI: 10.1529/biophysj.107.116525] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The skin secretions of Australian tree frogs are rich in peptides with potential antimicrobial activity. They interrupt bacterial cell membranes, although precisely how and whether all peptides have the same mechanism is not known. The interactions of three of these peptides-aurein 1.2, maculatin 1.1, and caerin 1.1 with supported phospholipid bilayers-are examined here using quartz crystal microbalance and atomic force microscopy. These approaches enabled us to reveal variations in material structure and density as a function of distance from the sensor surface when comparing mass sensorgrams over a range of harmonics of the natural resonance of the sensor crystal and hence obtain for the first time to our knowledge a mechanistic assessment of membrane disruption. We found that caerin inserted into the bilayer in a transmembrane manner, regardless of concentration and phospholipid composition consistent with a pore-forming mechanism. In contrast, maculatin and aurein interacted with membranes in a concentration-dependent manner. At low concentrations (<5 microM), maculatin exhibited transmembrane incorporation whereas aurein was limited to surface association. Upon reaching a threshold value of concentration, both peptides lysed the membrane. In the case of maculatin, the lysis progressed in a slow, concentration-dependent manner, forming mixed micelles, as shown by atomic force microscopy imaging. Aurein-induced lysis proceeded to a sudden disruption, which is consistent with the "carpet" mechanism. Both maculatin and aurein exhibit specificity toward phospholipids and thus have potential as candidates as antimicrobial drugs.
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Affiliation(s)
- Adam Mechler
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
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Seto GWJ, Marwaha S, Kobewka DM, Lewis RNAH, Separovic F, McElhaney RN. Interactions of the Australian tree frog antimicrobial peptides aurein 1.2, citropin 1.1 and maculatin 1.1 with lipid model membranes: differential scanning calorimetric and Fourier transform infrared spectroscopic studies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:2787-800. [PMID: 17825246 DOI: 10.1016/j.bbamem.2007.07.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 07/06/2007] [Accepted: 07/16/2007] [Indexed: 01/09/2023]
Abstract
The interactions of the antimicrobial peptides aurein 1.2, citropin 1.1 and maculatin 1.1 with dimyristoylphosphatidylcholine (DMPC), dimyristoylphosphatidylglycerol (DMPG) and dimyristoylphosphatidylethanolamine (DMPE) were studied by differential scanning calorimetry (DSC) and Fourier-transform infrared (FTIR) spectroscopy. The effects of these peptides on the thermotropic phase behavior of DMPC and DMPG are qualitatively similar and manifested by the suppression of the pretransition, and by peptide concentration-dependent decreases in the temperature, cooperativity and enthalpy of the gel/liquid-crystalline phase transition. However, at all peptide concentrations, anionic DMPG bilayers are more strongly perturbed than zwitterionic DMPC bilayers, consistent with membrane surface charge being an important aspect of the interactions of these peptides with phospholipids. However, at all peptide concentrations, the perturbation of the thermotropic phase behavior of zwitterionic DMPE bilayers is weak and discernable only when samples are exposed to high temperatures. FTIR spectroscopy indicates that these peptides are unstructured in aqueous solution and that they fold into alpha-helices when incorporated into lipid membranes. All three peptides undergo rapid and extensive H-D exchange when incorporated into D(2)O-hydrated phospholipid bilayers, suggesting that they are located in solvent-accessible environments, most probably in the polar/apolar interfacial regions of phospholipid bilayers. The perturbation of model lipid membranes by these peptides decreases in magnitude in the order maculatin 1.1>aurein 1.2>citropin 1.1, whereas the capacity to inhibit Acholeplasma laidlawii B growth decreases in the order maculatin 1.1>aurein 1.2 congruent with citropin 1.1. The higher efficacy of maculatin 1.1 in disrupting model and biological membranes can be rationalized by its larger size and higher net charge. However, despite its smaller size and lower net charge, aurein 1.2 is more disruptive of model lipid membranes than citropin 1.1 and exhibits comparable antimicrobial activity, probably because aurein 1.2 has a higher propensity for partitioning into phospholipid membranes.
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Affiliation(s)
- Gordon W J Seto
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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Pukala TL, Bowie JH, Maselli VM, Musgrave IF, Tyler MJ. Host-defence peptides from the glandular secretions of amphibians: structure and activity. Nat Prod Rep 2006; 23:368-93. [PMID: 16741585 DOI: 10.1039/b512118n] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Tara L Pukala
- Department of Chemistry, The University of Adelaide, South Australia
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Boland MP, Separovic F. Membrane interactions of antimicrobial peptides from Australian tree frogs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1178-83. [PMID: 16580625 DOI: 10.1016/j.bbamem.2006.02.010] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 02/04/2006] [Accepted: 02/11/2006] [Indexed: 12/25/2022]
Abstract
The skin secretions of amphibians are rich in host defence peptides. The membrane interactions of the antimicrobial peptides, aurein 1.2, citropin 1.1 and maculatin 1.1, isolated from Australian tree frogs, are reviewed. Although all three peptides are amphipathic alpha-helices, the mode of action of these membrane-active peptides is not defined. The peptides have a net positive charge and range in length from 13 to 21 residues, with the longest, maculatin 1.1, having a proline at position 15. Interestingly, alanine substitution at Pro-15 leads to loss of activity. The effects of these peptides on phospholipid bilayers indicate different mechanisms for pore formation and lysis of model membranes, with the shorter peptides exhibiting a carpet-like mechanism and the longest peptide forming pores in phospholipid bilayer membranes.
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Affiliation(s)
- Martin P Boland
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne VIC 3010, Australia
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Woodhams DC, Rollins-Smith LA, Carey C, Reinert L, Tyler MJ, Alford RA. Population trends associated with skin peptide defenses against chytridiomycosis in Australian frogs. Oecologia 2005; 146:531-40. [PMID: 16205955 DOI: 10.1007/s00442-005-0228-8] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Accepted: 07/25/2005] [Indexed: 11/30/2022]
Abstract
Many species of amphibians in the wet tropics of Australia have experienced population declines linked with the emergence of a skin-invasive chytrid fungus, Batrachochytrium dendrobatidis. An innate defense, antimicrobial peptides produced by granular glands in the skin, may protect some species from disease. Here we present evidence that supports this hypothesis. We tested ten synthesized peptides produced by Australian species, and natural peptide mixtures from five Queensland rainforest species. Natural mixtures and most peptides tested in isolation inhibited growth of B. dendrobatidis in vitro. The three most active peptides (caerin 1.9, maculatin 1.1, and caerin 1.1) were found in the secretions of non-declining species (Litoria chloris, L. caerulea, and L. genimaculata). Although the possession of a potent isolated antimicrobial peptide does not guarantee protection from infection, non-declining species (L. lesueuri and L. genimaculata) inhabiting the rainforest of Queensland possess mixtures of peptides that may be more protective than those of the species occurring in the same habitat that have recently experienced population declines associated with chytridiomycosis (L. nannotis, L. rheocola, and Nyctimystes dayi). This study demonstrates that in vitro effectiveness of skin peptides correlates with the degree of decline in the face of an emerging pathogen. Further research is needed to assess whether this non-specific immune defense may be useful in predicting disease susceptibility in other species.
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Affiliation(s)
- Douglas C Woodhams
- School of Tropical Biology, James Cook University, 4811, Townsville, QLD, Australia.
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Ambroggio EE, Separovic F, Bowie JH, Fidelio GD, Bagatolli LA. Direct visualization of membrane leakage induced by the antibiotic peptides: maculatin, citropin, and aurein. Biophys J 2005; 89:1874-81. [PMID: 15994901 PMCID: PMC1366690 DOI: 10.1529/biophysj.105.066589] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Membrane lysis caused by antibiotic peptides is often rationalized by means of two different models: the so-called carpet model and the pore-forming model. We report here on the lytic activity of antibiotic peptides from Australian tree frogs, maculatin 1.1, citropin 1.1, and aurein 1.2, on POPC or POPC/POPG model membranes. Leakage experiments using fluorescence spectroscopy indicated that the peptide/lipid mol ratio necessary to induce 50% of probe leakage was smaller for maculatin compared with aurein or citropin, regardless of lipid membrane composition. To gain further insight into the lytic mechanism of these peptides we performed single vesicle experiments using confocal fluorescence microscopy. In these experiments, the time course of leakage for different molecular weight (water soluble) fluorescent markers incorporated inside of single giant unilamellar vesicles is observed after peptide exposure. We conclude that maculatin and its related peptides demonstrate a pore-forming mechanism (differential leakage of small fluorescent probe compared with high molecular weight markers). Conversely, citropin and aurein provoke a total membrane destabilization with vesicle burst without sequential probe leakage, an effect that can be assigned to a carpeting mechanism of lytic action. Additionally, to study the relevance of the proline residue on the membrane-action properties of maculatin, the same experimental approach was used for maculatin-Ala and maculatin-Gly (Pro-15 was replaced by Ala or Gly, respectively). Although a similar peptide/lipid mol ratio was necessary to induce 50% of leakage for POPC membranes, the lytic activity of maculatin-Ala and maculatin-Gly decreased in POPC/POPG (1:1 mol) membranes compared with that observed for the naturally occurring maculatin sequence. As observed for maculatin, the lytic action of Maculatin-Ala and maculatin-Gly is in keeping with the formation of pore-like structures at the membrane independently of lipid composition.
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Affiliation(s)
- Ernesto E Ambroggio
- CIQUIBIC-CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Ciudad Universitaria, Córdoba, Argentina
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50
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Ambroggio EE, Separovic F, Bowie J, Fidelio GD. Surface behaviour and peptide–lipid interactions of the antibiotic peptides, Maculatin and Citropin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1664:31-7. [PMID: 15238255 DOI: 10.1016/j.bbamem.2004.03.013] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Revised: 03/02/2004] [Accepted: 03/24/2004] [Indexed: 11/23/2022]
Abstract
Surface behaviour of Maculatin 1.1 and Citropin 1.1 antibiotic peptides have been studied using the Langmuir monolayer technique in order to understand the peptide-membrane interaction proposed as critical for cellular lysis. Both peptides have a spontaneous adsorption at the air-water interface, reaching surface potentials similar to those obtained by direct spreading. Collapse pressures (Pi(c), stability to lateral compression), molecular areas at maximal packing and surface potentials (DeltaV) obtained from compression isotherms of both pure peptide monolayers are characteristic of peptides adopting mainly alpha-helical structure at the interface. The stability of Maculatin monolayers depended on the subphase and increased when pH was raised. In an alkaline environment, Maculatin exhibits a molecular reorganization showing a reproducible discontinuity in the Pi-A compression isotherm. Both peptides in lipid films with the zwitterionic palmitoyl-oleoyl-phosphatidylcholine (POPC) showed an immiscible behaviour at all lipid-peptide proportions studied. By contrast, in films with the anionic palmitoyl-oleoyl-phosphatidylglycerol (POPG), the peptides showed miscible behaviour when the peptides represented less than 50% of total surface area. Additional penetration experiments also demonstrated that both peptides better interact with POPG compared with POPC monolayers. This lipid preference is discussed as a possible explanation of their antibiotic properties.
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Affiliation(s)
- Ernesto E Ambroggio
- CIQUIBIC-CONICET-Departamento de Química Biológica, Facultad de Ciencias Químicas, Haya de la Torre y Medina Allende, Ciudad Universitaria, AP 4, Casilla de Correo 61, Córdoba (CP 5000), Argentina
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