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van der Walt M, Möller DS, van Wyk RJ, Ferguson PM, Hind CK, Clifford M, Do Carmo Silva P, Sutton JM, Mason AJ, Bester MJ, Gaspar ARM. QSAR Reveals Decreased Lipophilicity of Polar Residues Determines the Selectivity of Antimicrobial Peptide Activity. ACS OMEGA 2024; 9:26030-26049. [PMID: 38911757 PMCID: PMC11191095 DOI: 10.1021/acsomega.4c01277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 05/15/2024] [Accepted: 05/20/2024] [Indexed: 06/25/2024]
Abstract
Antimicrobial resistance has increased rapidly, causing daunting morbidity and mortality rates worldwide. Antimicrobial peptides (AMPs) have emerged as promising alternatives to traditional antibiotics due to their broad range of targets and low tendency to elicit resistance. However, potent antimicrobial activity is often accompanied by excessive cytotoxicity toward host cells, leading to a halt in AMP therapeutic development. Here, we present multivariate analyses that correlate 28 peptide properties to the activity and toxicity of 46 diverse African-derived AMPs and identify the negative lipophilicity of polar residues as an essential physiochemical property for selective antimicrobial activity. Twenty-seven active AMPs are identified, of which the majority are of scorpion or frog origin. Of these, thirteen are novel with no previously reported activities. Principal component analysis and quantitative structure-activity relationships (QSAR) reveal that overall hydrophobicity, lipophilicity, and residue side chain surface area affect the antimicrobial and cytotoxic activity of an AMP. This has been well documented previously, but the present QSAR analysis additionally reveals that a decrease in the lipophilicity, contributed by those amino acids classified as polar, confers selectivity for a peptide to pathogen over mammalian cells. Furthermore, an increase in overall peptide charge aids selectivity toward Gram-negative bacteria and fungi, while selectivity toward Gram-positive bacteria is obtained through an increased number of small lipophilic residues. Finally, a conservative increase in peptide size in terms of sequence length and molecular weight also contributes to improved activity without affecting toxicity. Our findings suggest a novel approach for the rational design or modification of existing AMPs to increase pathogen selectivity and enhance therapeutic potential.
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Affiliation(s)
- Mandelie van der Walt
- Department
of Biochemistry, Genetics and Microbiology, Faculty of Natural and
Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa
| | - Dalton S. Möller
- Department
of Biochemistry, Genetics and Microbiology, Faculty of Natural and
Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa
| | - Rosalind J. van Wyk
- Department
of Biochemistry, Genetics and Microbiology, Faculty of Natural and
Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa
| | - Philip M. Ferguson
- Institute
of Pharmaceutical Science, School of Cancer & Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford
Street, London SE1 9NH, United Kingdom
| | - Charlotte K. Hind
- Antimicrobial
Discovery Development and Diagnostics, Vaccine Evaluation and Development
Centre, UK Health Security Agency, Salisbury SP4 0JG, United Kingdom
| | - Melanie Clifford
- Antimicrobial
Discovery Development and Diagnostics, Vaccine Evaluation and Development
Centre, UK Health Security Agency, Salisbury SP4 0JG, United Kingdom
| | - Phoebe Do Carmo Silva
- Antimicrobial
Discovery Development and Diagnostics, Vaccine Evaluation and Development
Centre, UK Health Security Agency, Salisbury SP4 0JG, United Kingdom
| | - J. Mark Sutton
- Antimicrobial
Discovery Development and Diagnostics, Vaccine Evaluation and Development
Centre, UK Health Security Agency, Salisbury SP4 0JG, United Kingdom
| | - A. James Mason
- Institute
of Pharmaceutical Science, School of Cancer & Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford
Street, London SE1 9NH, United Kingdom
| | - Megan J. Bester
- Department
of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa
| | - Anabella R. M. Gaspar
- Department
of Biochemistry, Genetics and Microbiology, Faculty of Natural and
Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa
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Wu J, Zhou X, Chen Q, Chen Z, Zhang J, Yang L, Sun Y, Wang G, Dai J, Feng T. Defensins as a promising class of tick antimicrobial peptides: a scoping review. Infect Dis Poverty 2022; 11:71. [PMID: 35725522 PMCID: PMC9208123 DOI: 10.1186/s40249-022-00996-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 06/06/2022] [Indexed: 11/11/2022] Open
Abstract
Background Ticks are hematophagous parasites that transmit an extensive range of pathogens to their vertebrate hosts. Ticks can destroy invading microorganisms or alleviate infection via their rudimentary but orchestrated innate immune system. Antimicrobial peptides (AMPs) are important components of tick innate immunity. Among these humoral effector molecules, defensins are well-studied and widely identified in various species of Ixodidae (hard ticks) and Argasidae (soft ticks). This review was aimed at presenting the characterization of tick defensins from structure-based taxonomic status to antimicrobial function. Main text All published papers written in English from 2001 to May 2022 were searched through PubMed and Web of Science databases with the combination of relevant terms on tick defensins. Reports on identification and characterization of tick defensins were included. Of the 329 entries retrieved, 57 articles were finally eligible for our scoping review. Tick defensins mainly belong to the antibacterial ancient invertebrate-type defensins of the cis-defensins superfamily. They are generally small, cationic, and amphipathic, with six cysteine residues forming three intra-molecular disulfide bonds. Tick defensins primarily target membranes of a variety of pathogens, including Gram-positive and Gram-negative bacteria, fungi, viruses, and protozoa. Since tick defensins have a high degree of variability, we summarize their common biological properties and enumerate representative peptides. Along with the various and potent antimicrobial activities, the role of tick defensins in determining vector competence is discussed. Conclusions Due to their broad-spectrum antimicrobial activities, tick defensins are considered novel candidates or targets for controlling infectious diseases. Graphical Abstract ![]()
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Affiliation(s)
- Jiahui Wu
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China
| | - Xia Zhou
- School of Biology and Basic Medical Science, Suzhou Medical College of Soochow University, Suzhou, China
| | - Qiaoqiao Chen
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China
| | - Zhiqiang Chen
- Department of Nuclear Medicine, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Jinyu Zhang
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China
| | - Lele Yang
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China
| | - Yuxuan Sun
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China
| | - Guohui Wang
- School of Life Science and Technology, Weifang Medical University, Weifang, China.
| | - Jianfeng Dai
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China.
| | - Tingting Feng
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China.
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3
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Mbuayama KR, Taute H, Strӧmstedt AA, Bester MJ, Gaspar ARM. Antifungal activity and mode of action of synthetic peptides derived from the tick OsDef2 defensin. J Pept Sci 2021; 28:e3383. [PMID: 34866278 DOI: 10.1002/psc.3383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/28/2021] [Accepted: 11/08/2021] [Indexed: 01/29/2023]
Abstract
Candida albicans is the principal opportunistic fungal pathogen in nosocomial settings and resistance to antifungal drugs is on the rise. Antimicrobial peptides from natural sources are promising novel therapeutics against C. albicans. OsDef2 defensin was previously found to be active against only Gram-positive bacteria, whereas derived fragments Os and its cysteine-free analogue, Os-C, are active against Gram-positive and Gram-negative bacteria at low micromolar concentrations. In this study, OsDef2-derived analogues and fragments were screened for anticandidal activity with the aim to identify peptides with antifungal activity and in so doing obtain a better understanding of the structural requirements for activity and modes of action. Os, Os-C and Os(11-22)NH2 , a Os-truncated carboxy-terminal-amidated fragment, had the most significant antifungal activities, with minimum fungicidal concentrations (MFCs) in the micromolar range (6-28 μM). C. albicans killing was rapid and occurred within 30-60 min. Further investigations showed all three peptides interacted with cell wall derived polysaccharides while both Os and Os(11-22)NH2 permeabilized fungal liposomes. Confocal laser scanning microscopy confirmed that Os-C and Os(11-22)NH2 could enter the cytosol of live cells and subsequent findings suggest that the uptake of Os and Os-C, in contrast to Os(11-22)NH2 , is energy dependent. Although Os, Os-C and Os(11-22)NH2 induced the production of reactive oxygen species (ROS), co-incubation with ascorbic acid revealed that only ROS generated by Os-C and to a lesser extent Os(11-22)NH2 resulted in cell death. Overall, Os, Os-C and Os(11-22)NH2 are promising candidacidal agents.
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Affiliation(s)
- Kabuzi R Mbuayama
- Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
| | - Helena Taute
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Adam A Strӧmstedt
- Pharmacognosy, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Megan J Bester
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Anabella R M Gaspar
- Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
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Mahlapuu M, Björn C, Ekblom J. Antimicrobial peptides as therapeutic agents: opportunities and challenges. Crit Rev Biotechnol 2020; 40:978-992. [PMID: 32781848 DOI: 10.1080/07388551.2020.1796576] [Citation(s) in RCA: 209] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The rapid development of microbial resistance to conventional antibiotics has accelerated efforts to find anti-infectives with a novel mode-of-action, which are less prone to bacterial resistance. Intense nonclinical and clinical research is today ongoing to evaluate antimicrobial peptides (AMPs) as potential next-generation antibiotics. Currently, multiple AMPs are assessed in late-stage clinical trials, not only as novel anti-infective drugs, but also as innovative product candidates for immunomodulation, promotion of wound healing, and prevention of post-operative scars. The efforts to translate AMP-based research findings into pharmaceutical product candidates are expected to accelerate in coming years due to technological advancements in multiple areas, including an improved understanding of the mechanism-of-action of AMPs, smart formulation strategies, and advanced chemical synthesis protocols. At the same time, it is recognized that cytotoxicity, low metabolic stability due to sensitivity to proteolytic degradation, and limited oral bioavailability are some of the key weaknesses of AMPs. Furthermore, the pricing and reimbursement environment for new antimicrobial products remains as a major barrier to the commercialization of AMPs.
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Affiliation(s)
- Margit Mahlapuu
- Promore Pharma AB, Karolinska Institutet Science Park, Solna, Sweden
| | | | - Jonas Ekblom
- Promore Pharma AB, Karolinska Institutet Science Park, Solna, Sweden
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