1
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Ookubo M, Tashiro Y, Asano K, Kamei Y, Tanaka Y, Honda T, Yokoyama T, Honda M. "Rich arginine and strong positive charge" antimicrobial protein protamine: From its action on cell membranes to inhibition of bacterial vital functions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184323. [PMID: 38614236 DOI: 10.1016/j.bbamem.2024.184323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/15/2024] [Accepted: 04/05/2024] [Indexed: 04/15/2024]
Abstract
Protamine, an antimicrobial protein derived from salmon sperm with a molecular weight of approximately 5 kDa, is composed of 60-70 % arginine and is a highly charged protein. Here, we investigated the mechanism of antimicrobial action of protamine against Cutibacterium acnes (C. acnes) focusing on its rich arginine content and strong positive charge. Especially, we focused on the attribution of dual mechanisms of antimicrobial protein, including membrane disruption or interaction with intracellular components. We first determined the dose-dependent antibacterial activity of protamine against C. acnes. In order to explore the interaction between bacterial membrane and protamine, we analyzed cell morphology, zeta potential, membrane permeability, and the composition of membrane fatty acid. In addition, the localization of protamine in bacteria was observed using fluorescent-labeled protamine. For investigation of the intracellular targets of protamine, bacterial translation was examined using a cell-free translation system. Based on our results, the mechanism of the antimicrobial action of protamine against C. acnes is as follows: 1) electrostatic interactions with the bacterial cell membrane; 2) self-internalization into the bacterial cell by changing the composition of the bacterial membrane; and 3) inhibition of bacterial growth by blocking translation inside the bacteria. However, owing to its strong electric charge, protamine can also interact with DNA, RNA, and other proteins inside the bacteria, and may inhibit various bacterial life processes beyond the translation process.
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Affiliation(s)
- Momoka Ookubo
- Graduate School of Science and Technology, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki 214-8571, Kanagawa, Japan
| | - Yuka Tashiro
- Graduate School of Science and Technology, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki 214-8571, Kanagawa, Japan
| | - Kosuke Asano
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai 980-8577, Japan
| | - Yoshiharu Kamei
- Graduate School of Science and Technology, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki 214-8571, Kanagawa, Japan
| | - Yoshikazu Tanaka
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai 980-8577, Japan; The advanced center for innovations in next-generation medicine (INGEM), Tohoku University, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8573, Japan
| | - Takayuki Honda
- Graduate School of Science and Technology, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki 214-8571, Kanagawa, Japan
| | - Takeshi Yokoyama
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai 980-8577, Japan; The advanced center for innovations in next-generation medicine (INGEM), Tohoku University, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8573, Japan
| | - Michiyo Honda
- Graduate School of Science and Technology, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki 214-8571, Kanagawa, Japan.
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2
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Wu CL, Peng KL, Yip BS, Chih YH, Cheng JW. Boosting Synergistic Effects of Short Antimicrobial Peptides With Conventional Antibiotics Against Resistant Bacteria. Front Microbiol 2021; 12:747760. [PMID: 34733262 PMCID: PMC8558513 DOI: 10.3389/fmicb.2021.747760] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/27/2021] [Indexed: 01/10/2023] Open
Abstract
The global spread of antibiotic-resistant infections has meant that there is an urgent need to develop new antimicrobial alternatives. In this study, we developed a strategy to boost and/or synergize the activity of conventional antibiotics by combination with antimicrobial peptides tagged with the bulky non-natural amino acid β-naphthylalanine (Nal) to their N- or C-terminus. A checkerboard method was used to evaluate synergistic effects of the parent peptide and the Nal-tagged peptides. Moreover, boron-dipyrro-methene labeled vancomycin was used to characterize the synergistic mechanism of action between the peptides and vancomycin on the bacterial strains. These Nal-tagged antimicrobial peptides also reduced the antibiotic-induced release of lipopolysaccharide from Gram-negative bacteria by more than 99.95%. Our results demonstrate that Nal-tagged peptides could help in developing antimicrobial peptides that not only have enhanced antibacterial activities but also increase the synergistic effects with conventional antibiotics against antibiotic-resistant bacteria.
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Affiliation(s)
- Chih-Lung Wu
- Department of Medical Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu, Taiwan
| | - Kuang-Li Peng
- Department of Medical Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu, Taiwan
| | - Bak-Sau Yip
- Department of Medical Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu, Taiwan.,Department of Neurology, National Taiwan University Hospital Hsinchu Branch, Hsinchu, Taiwan
| | - Ya-Han Chih
- Department of Medical Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu, Taiwan
| | - Jya-Wei Cheng
- Department of Medical Science, Institute of Biotechnology, National Tsing Hua University, Hsinchu, Taiwan
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3
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Kumar P, Saha T, Behera S, Gupta S, Das S, Mukhopadhyay K. Enhanced efficacy of a Cu 2+ complex of curcumin against Gram-positive and Gram-negative bacteria: Attributes of complex formation. J Inorg Biochem 2021; 222:111494. [PMID: 34091095 DOI: 10.1016/j.jinorgbio.2021.111494] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 05/14/2021] [Accepted: 05/24/2021] [Indexed: 01/12/2023]
Abstract
Curcumin is a tantalizing molecule with multifaceted therapeutic potentials. However, its therapeutic applications are severely hampered because of poor bioavailability, attributed to its instability and aqueous insolubility. In an attempt to overcome this inherent limitation and develop curcumin-based antibacterials, we had earlier synthesized and characterized a metal complex of Cu(II) with curcumin, having the formula [Cu(Curcumin)(OCOCH3)(H2O)], hereafter referred to as Cu(Cur). In this study, the complex, i.e., Cu(Cur), was investigated for its stability and antibacterial activity along with its possible mechanism of action in comparison to the parent molecule, curcumin. Complex formation resulted in improved stability as Cu(Cur) was found to be highly stable under different physiological conditions. Such improved stability was verified with the help of UV-Vis spectroscopy and HPLC. With improved stability, Cu(Cur) exhibited potent and significantly enhanced activity over curcumin against both E. coli and S. aureus. Calcein leakage assay revealed that the complex triggered immediate membrane permeabilization in S. aureus. This membrane disruptive mode of action was further corroborated by microscopic visualization. The excellent potency of the complex was augmented by its safe toxicological profile as it was non-hemolytic and non-cytotoxic towards mammalian cells, making it a suitable candidate for in vivo investigations. Altogether, this investigation is a critical appraisal that advocates the antibacterial potential of this stable, membrane-targeting and non-toxic complex, thereby presenting new perspectives for its therapeutic application against bacterial infections.
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Affiliation(s)
- Prince Kumar
- Antimicrobial Research Laboratory, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India
| | - Tanmoy Saha
- Department of Chemistry (Inorganic Section), Jadavpur University, Kolkata 700 032, India
| | - Swastik Behera
- Antimicrobial Research Laboratory, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India
| | - Shalini Gupta
- Molecular Biology Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110 067, India
| | - Saurabh Das
- Department of Chemistry (Inorganic Section), Jadavpur University, Kolkata 700 032, India
| | - Kasturi Mukhopadhyay
- Antimicrobial Research Laboratory, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India.
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4
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Wieland T, Assmann J, Bethe A, Fidelak C, Gmoser H, Janßen T, Kotthaus K, Lübke-Becker A, Wieler LH, Urban GA. A Real-Time Thermal Sensor System for Quantifying the Inhibitory Effect of Antimicrobial Peptides on Bacterial Adhesion and Biofilm Formation. SENSORS 2021; 21:s21082771. [PMID: 33919962 PMCID: PMC8070953 DOI: 10.3390/s21082771] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 01/15/2023]
Abstract
The increasing rate of antimicrobial resistance (AMR) in pathogenic bacteria is a global threat to human and veterinary medicine. Beyond antibiotics, antimicrobial peptides (AMPs) might be an alternative to inhibit the growth of bacteria, including AMR pathogens, on different surfaces. Biofilm formation, which starts out as bacterial adhesion, poses additional challenges for antibiotics targeting bacterial cells. The objective of this study was to establish a real-time method for the monitoring of the inhibition of (a) bacterial adhesion to a defined substrate and (b) biofilm formation by AMPs using an innovative thermal sensor. We provide evidence that the thermal sensor enables continuous monitoring of the effect of two potent AMPs, protamine and OH-CATH-30, on surface colonization of bovine mastitis-associated Escherichia (E.) coli and Staphylococcus (S.) aureus. The bacteria were grown under static conditions on the surface of the sensor membrane, on which temperature oscillations generated by a heater structure were detected by an amorphous germanium thermistor. Bacterial adhesion, which was confirmed by white light interferometry, caused a detectable amplitude change and phase shift. To our knowledge, the thermal measurement system has never been used to assess the effect of AMPs on bacterial adhesion in real time before. The system could be used to screen and evaluate bacterial adhesion inhibition of both known and novel AMPs.
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Affiliation(s)
- Tobias Wieland
- Department of Microsystems Engineering (IMTEK)—Laboratory of Sensors, University of Freiburg, 79110 Freiburg, Germany; (H.G.); (K.K.); (G.A.U.)
- Correspondence: ; Tel.: +49-761-203-7268
| | - Julia Assmann
- Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany; (J.A.); (A.B.); (A.L.-B.); (L.H.W.)
- Robert Koch Institute, ZBS4 Advanced Light and Electron Microscopy, 13353 Berlin, Germany
| | - Astrid Bethe
- Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany; (J.A.); (A.B.); (A.L.-B.); (L.H.W.)
| | | | - Helena Gmoser
- Department of Microsystems Engineering (IMTEK)—Laboratory of Sensors, University of Freiburg, 79110 Freiburg, Germany; (H.G.); (K.K.); (G.A.U.)
| | | | - Krishan Kotthaus
- Department of Microsystems Engineering (IMTEK)—Laboratory of Sensors, University of Freiburg, 79110 Freiburg, Germany; (H.G.); (K.K.); (G.A.U.)
| | - Antina Lübke-Becker
- Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany; (J.A.); (A.B.); (A.L.-B.); (L.H.W.)
| | - Lothar H. Wieler
- Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany; (J.A.); (A.B.); (A.L.-B.); (L.H.W.)
- Robert Koch Institute, 13353 Berlin, Germany
| | - Gerald A. Urban
- Department of Microsystems Engineering (IMTEK)—Laboratory of Sensors, University of Freiburg, 79110 Freiburg, Germany; (H.G.); (K.K.); (G.A.U.)
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5
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Saha T, Kumar P, Sepay N, Ganguly D, Tiwari K, Mukhopadhyay K, Das S. Multitargeting Antibacterial Activity of a Synthesized Mn 2+ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains. ACS OMEGA 2020; 5:16342-16357. [PMID: 32685797 PMCID: PMC7364437 DOI: 10.1021/acsomega.9b04079] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 06/16/2020] [Indexed: 05/05/2023]
Abstract
Curcumin is an important molecule with a plethora of pharmacological activities and therapeutic potentials. Despite its efficacy, it remained a potential drug candidate owing to hydrolytic instability and poor aqueous solubility. To overcome the limitations related to low solubility, low bioavailability, and the fact that curcumin is never present in solution as a "single unit", its complex was prepared with MnII with the idea that binding to a metal ion might help to resolve these issues. The complex was characterized by elemental and spectral analysis. The structure of the complex was determined by density functional theory calculations. The complex was stable at physiological buffer conditions, unlike curcumin. It did not have any detrimental effect on mammalian cells. There was a significant enhancement in the antibacterial activity of the complex compared to curcumin against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. It showed a strong affinity for deoxyribonucleic acid (DNA) evident from a high binding constant value with calf thymus DNA and also from the retarded electrophoretic mobility of bacterial plasmid DNA. The complex showed "superoxide dismutase-like" activity leading to the generation of reactive oxygen species (ROS). The complex caused bacterial membrane perturbation evident from calcein leakage assay, which was further corroborated by scanning and transmission electron microscopic experiments. Overall, the present study shows improved stability and antibacterial potency of a nontoxic complex over curcumin. Its multitargeting mode of action such as ROS-production, effective binding with DNA, and permeabilization of bacterial membrane together allows it to be an effective antibacterial agent that could be taken further for therapeutic use against bacterial infections.
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Affiliation(s)
- Tanmoy Saha
- Department
of Chemistry, Jadavpur University, Kolkata 700032, India
| | - Prince Kumar
- School
of Environmental Sciences, Jawaharlal Nehru
University, New Delhi 110067, India
| | - Nayim Sepay
- Department
of Chemistry, Jadavpur University, Kolkata 700032, India
| | - Durba Ganguly
- Department
of Inorganic Chemistry, Indian Association
for the Cultivation of Science, Kolkata 700032, India
| | - Kanchan Tiwari
- School
of Environmental Sciences, Jawaharlal Nehru
University, New Delhi 110067, India
| | - Kasturi Mukhopadhyay
- School
of Environmental Sciences, Jawaharlal Nehru
University, New Delhi 110067, India
| | - Saurabh Das
- Department
of Chemistry, Jadavpur University, Kolkata 700032, India
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6
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Aziz M, Garduno R, Mirani ZA, Baqai R, Sheikh AS, Nazir H, Raza Y, Ayaz M, Kazmi SU. Determination of antimicrobial effect of protamine by transmission electron microscopy and SDS PAGE on Pseudomonas aeruginosa isolates from diabetic foot infection. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2020; 22:827-832. [PMID: 32373306 PMCID: PMC7196347 DOI: 10.22038/ijbms.2019.32414.7989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Objective(s): Diabetic foot infection is one of the major complications of diabetes leading to lower limb amputations. Isolation and identification of bacteria causing diabetic foot infection, determination of antibiotic resistance, antimicrobial potential of protamine by electron microscopy and SDS-PAGE analysis, arethe aims of this study. Materials and Methods: 285 pus samples from diabetic foot infection patients were collected from different hospitals of Karachi and Capital Health Hospital, Halifax, Canada. Clinical history of each patient was recorded. Bacterial isolates were cultured on appropriate media; identification was done by morphology, cultural and biochemical tests. Effect of protamine against multi drug resistant strains of Pseudomona aeruginosa was checked by minimum inhibitory concentration in 96 well micro-titer plates. The isolates were grown in bactericidal concentration of protamine on plates to isolate mutants. Effect of protamine on protein expression was checked by SDS- PAGE and ultra-structural morphological changes by transmission electron microscopy. Results: Results indicated prevalence of foot infection as 92% in diabetic patients. Major bacterial isolates were Staphylococcus aureus 65 (23%), P. aeruginosa 80 (28.1%), Klebsiella spp. 37 (13%), Proteus mirabilis 79 (27.7%), and Escherichia coli 24 (12%). These isolates were highly resistant to different antibiotics. MIC value of protamine was 500 µg/ml against P. aeruginosa. SDS-PAGE analysis revealed that protamine can suppress expression of various virulence proteins and electron micrographs indicated condensation of cytoplasm and accumulation of protamine in cytoplasm without damaging the cell membrane. Conclusion: P. aeruginosa and S. aureus were the major isolates expressing multi-drug resistance and protamine sulfate represented good antimicrobial potential.
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Affiliation(s)
- Mubashar Aziz
- Department of Pathobiology, Bahauddin Zakariya University, Multan, Pakistan.,Department of Microbiology, University of Karachi, Karachi, Pakistan
| | - Rafael Garduno
- Department of Microbiology, Dalhousie University, Halifax, Canada
| | | | - Rakhshanda Baqai
- Department of Microbiology, University of Karachi, Karachi, Pakistan.,Departmet of Clinical Microbiology & Immunology, Dadabhoy Institute of Higher Education, Karachi, Pakistan
| | - Ahsan Sattar Sheikh
- Institute of Food Science and Nutrition, Bahauddin Zakariya University, Multan, Pakistan
| | | | - Yasir Raza
- Department of Microbiology, University of Karachi, Karachi, Pakistan
| | - Mazhar Ayaz
- Department of Pathobiology, Bahauddin Zakariya University, Multan, Pakistan
| | - Shahana Urooj Kazmi
- Department of Microbiology, University of Karachi, Karachi, Pakistan.,Departmet of Clinical Microbiology & Immunology, Dadabhoy Institute of Higher Education, Karachi, Pakistan
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7
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Pseudomonas aeruginosa Increases the Sensitivity of Biofilm-Grown Staphylococcus aureus to Membrane-Targeting Antiseptics and Antibiotics. mBio 2019; 10:mBio.01501-19. [PMID: 31363032 PMCID: PMC6667622 DOI: 10.1128/mbio.01501-19] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The thick mucus in the airways of cystic fibrosis (CF) patients predisposes them to frequent, polymicrobial respiratory infections. Pseudomonas aeruginosa and Staphylococcus aureus are frequently coisolated from the airways of individuals with CF, as well as from diabetic foot ulcers and other wounds. Both organisms form biofilms, which are notoriously difficult to eradicate and promote chronic infection. In this study, we have shown that P. aeruginosa-secreted factors can increase the efficacy of compounds that alone have little or no bactericidal activity against S. aureus biofilms. In particular, we discovered that P. aeruginosa exoproducts can potentiate the antistaphylococcal activity of phenol-based antiseptics and other membrane-active drugs. Our findings illustrate that polymicrobial interactions can dramatically increase antibacterial efficacy in vitro and suggest that altering membrane physiology promotes the ability of certain drugs to kill bacterial biofilms—knowledge that may provide a path for the discovery of new biofilm-targeting antimicrobial strategies. Pseudomonas aeruginosa and Staphylococcus aureus often cause chronic, recalcitrant infections in large part due to their ability to form biofilms. The biofilm mode of growth enables these organisms to withstand antibacterial insults that would effectively eliminate their planktonic counterparts. We found that P. aeruginosa supernatant increased the sensitivity of S. aureus biofilms to multiple antimicrobial compounds, including fluoroquinolones and membrane-targeting antibacterial agents, including the antiseptic chloroxylenol. Treatment of S. aureus with the antiseptic chloroxylenol alone did not decrease biofilm cell viability; however, the combination of chloroxylenol and P. aeruginosa supernatant led to a 4-log reduction in S. aureus biofilm viability compared to exposure to chloroxylenol alone. We found that the P. aeruginosa-produced small molecule 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO) is responsible for the observed heightened sensitivity of S. aureus to chloroxylenol. Similarly, HQNO increased the susceptibility of S. aureus biofilms to other compounds, including both traditional and nontraditional antibiotics, which permeabilize bacterial membranes. Genetic and phenotypic studies support a model whereby HQNO causes an increase in S. aureus membrane fluidity, thereby improving the efficacy of membrane-targeting antiseptics and antibiotics. Importantly, our data show that P. aeruginosa exoproducts can enhance the ability of various antimicrobial agents to kill biofilm populations of S. aureus that are typically difficult to eradicate. Finally, our discovery that altering membrane fluidity shifts antimicrobial sensitivity profiles of bacterial biofilms may guide new approaches to target persistent infections, such as those commonly found in respiratory tract infections and in chronic wounds.
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8
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Kumar S, Kumar A, Kaushal M, Kumar P, Mukhopadhyay K, Kumar A. Fungal-derived xenobiotic exhibits antibacterial and antibiofilm activity against Staphylococcus aureus . Drug Discov Ther 2018; 12:214-223. [DOI: 10.5582/ddt.2018.01042] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | - Arvind Kumar
- Department of Biotechnology, Central University of South Bihar
| | - Manisha Kaushal
- Department of Botany, Gurunakak Degree College Umra kala Siohara
| | - Prince Kumar
- School of Environmental Sciences, Jawaharlal Nehru University
| | | | - Antresh Kumar
- Department of Biotechnology, Central University of South Bihar
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9
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López-Pérez PM, Grimsey E, Bourne L, Mikut R, Hilpert K. Screening and Optimizing Antimicrobial Peptides by Using SPOT-Synthesis. Front Chem 2017; 5:25. [PMID: 28447030 PMCID: PMC5388751 DOI: 10.3389/fchem.2017.00025] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 03/29/2017] [Indexed: 11/14/2022] Open
Abstract
Peptide arrays on cellulose are a powerful tool to investigate peptide interactions with a number of different molecules, for examples antibodies, receptors or enzymes. Such peptide arrays can also be used to study interactions with whole cells. In this review, we focus on the interaction of small antimicrobial peptides with bacteria. Antimicrobial peptides (AMPs) can kill multidrug-resistant (MDR) human pathogenic bacteria and therefore could be next generation antibiotics targeting MDR bacteria. We describe the screen and the result of different optimization strategies of peptides cleaved from the membrane. In addition, screening of antibacterial activity of peptides that are tethered to the surface is discussed. Surface-active peptides can be used to protect surfaces from bacterial infections, for example implants.
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Affiliation(s)
| | - Elizabeth Grimsey
- Institute for Infection and Immunity, St. George's University of LondonLondon, UK
| | - Luc Bourne
- Institute for Infection and Immunity, St. George's University of LondonLondon, UK
| | - Ralf Mikut
- Karlsruhe Institute of Technology (KIT), Institute for Applied Computer Science (IAI)Eggenstein-Leopoldshafen, Germany
| | - Kai Hilpert
- TiKa Diagnostics LtdLondon, UK
- Institute for Infection and Immunity, St. George's University of LondonLondon, UK
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10
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Targeting biofilms and persisters of ESKAPE pathogens with P14KanS, a kanamycin peptide conjugate. Biochim Biophys Acta Gen Subj 2017; 1861:848-859. [PMID: 28132897 DOI: 10.1016/j.bbagen.2017.01.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/19/2017] [Accepted: 01/26/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND The worldwide emergence of antibiotic resistance represents a serious medical threat. The ability of these resistant pathogens to form biofilms that are highly tolerant to antibiotics further aggravates the situation and leads to recurring infections. Thus, new therapeutic approaches that adopt novel mechanisms of action are urgently needed. To address this significant problem, we conjugated the antibiotic kanamycin with a novel antimicrobial peptide (P14LRR) to develop a kanamycin peptide conjugate (P14KanS). METHODS Antibacterial activities were evaluated in vitro and in vivo using a Caenorhabditis elegans model. Additionally, the mechanism of action, antibiofilm activity and anti-inflammatory effect of P14KanS were investigated. RESULTS P14KanS exhibited potent antimicrobial activity against ESKAPE pathogens. P14KanS demonstrated a ≥128-fold improvement in MIC relative to kanamycin against kanamycin-resistant strains. Mechanistic studies confirmed that P14KanS exerts its antibacterial effect by selectively disrupting the bacterial cell membrane. Unlike many antibiotics, P14KanS demonstrated rapid bactericidal activity against stationary phases of both Gram-positive and Gram-negative pathogens. Moreover, P14KanS was superior in disrupting adherent bacterial biofilms and in killing intracellular pathogens as compared to conventional antibiotics. Furthermore, P14KanS demonstrated potent anti-inflammatory activity via the suppression of LPS-induced proinflammatory cytokines. Finally, P14KanS protected C. elegans from lethal infections of both Gram-positive and Gram-negative pathogens. CONCLUSIONS The potent in vitro and in vivo activity of P14KanS warrants further investigation as a potential therapeutic agent for bacterial infections. GENERAL SIGNIFICANCE This study demonstrates that equipping kanamycin with an antimicrobial peptide is a promising method to tackle bacterial biofilms and address bacterial resistance to aminoglycosides.
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11
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Dosunmu EF, Chaudhari AA, Bawage S, Bakeer MK, Owen DR, Singh SR, Dennis VA, Pillai SR. Novel cationic peptide TP359 down-regulates the expression of outer membrane biogenesis genes in Pseudomonas aeruginosa: a potential TP359 anti-microbial mechanism. BMC Microbiol 2016; 16:192. [PMID: 27549081 PMCID: PMC4994277 DOI: 10.1186/s12866-016-0808-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 08/10/2016] [Indexed: 11/18/2022] Open
Abstract
Background Antimicrobial peptides (AMPs) are a class of antimicrobial agents with broad-spectrum activities. Several reports indicate that cationic AMPs bind to the negatively charged bacterial membrane causing membrane depolarization and damage. However, membrane depolarization and damage may be insufficient to elicit cell death, thereby suggesting that other mechanism(s) of action could be involved in this phenomenon. In this study, we investigated the antimicrobial activity of a novel antimicrobial peptide, TP359, against two strains of Pseudomonas aeruginosa, as well as its possible mechanisms of action. Results TP359 proved to be bactericidal against P. aeruginosa as confirmed by the reduced bacteria counts, membrane damage and cytoplasmic membrane depolarization. In addition, it was non-toxic to mouse J774 macrophages and human lung A549 epithelial cells. Electron microscopy analysis showed TP359 bactericidal effects by structural changes of the bacteria from viable rod-shaped cells to those with cell membrane damages, proceeding into the efflux of cytoplasmic contents and emergence of ghost cells. Gene expression analysis on the effects of TP359 on outer membrane biogenesis genes underscored marked down-regulation, particularly of oprF, which encodes a major structural and outer membrane porin (OprF) in both strains studied, indicating that the peptide may cause deregulation of outer membrane genes and reduced structural stability which could lead to cell death. Conclusion Our data shows that TP359 has potent antimicrobial activity against P aeruginosa. The correlation between membrane damage, depolarization and reduced expression of outer membrane biogenesis genes, particularly oprF may suggest the bactericidal mechanism of action of the TP359 peptide. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0808-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ejovwoke F Dosunmu
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL, USA
| | - Atul A Chaudhari
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL, USA
| | - Swapnil Bawage
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL, USA
| | - Mona K Bakeer
- LSU Health Sciences Center, School of Allied Health Professions, New Orleans, LA, USA
| | | | - Shree R Singh
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL, USA
| | - Vida A Dennis
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL, USA
| | - Shreekumar R Pillai
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL, USA.
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12
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Antibacterial Peptides: Opportunities for the Prevention and Treatment of Dental Caries. Probiotics Antimicrob Proteins 2016; 3:68. [PMID: 26781572 DOI: 10.1007/s12602-011-9076-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Dental caries is a multifactorial disease that is a growing and costly global health concern. The onset of disease is a consequence of an ecological imbalance within the dental plaque biofilm that favors specific acidogenic and aciduric caries pathogens, namely Streptococcus mutans and Streptococcus sobrinus. It is now recognized by the scientific and medical community that it is neither possible nor desirable to totally eliminate dental plaque. Conversely, the chemical biocides most commonly used for caries prevention and treatment indiscriminately attack all plaque microorganisms. These treatments also suffer from other drawbacks such as bad taste, irritability, and staining. Furthermore, the public demand for safe and natural personal hygiene products continues to rise. Therefore, there are opportunities that exist to develop new strategies for the treatment of this disease. As an alternative to conventional antibiotics, antibacterial peptides have been explored greatly over the last three decades for many different therapeutic uses. There are currently tens of hundreds of antibacterial peptides characterized across the evolutionary spectrum, and among these, many demonstrate physical and/or biological properties that may be suitable for a more targeted approach to the selective control or elimination of putative caries pathogens. Additionally, many peptides, such as nisin, are odorless, colorless, and tasteless and do not cause irritation or staining. This review focuses on antibacterial peptides for their potential role in the treatment and prevention of dental caries and suggests candidates that need to be explored further. Practical considerations for the development of antibacterial peptides as oral treatments are also discussed.
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The Potential Use of Natural and Structural Analogues of Antimicrobial Peptides in the Fight against Neglected Tropical Diseases. Molecules 2015; 20:15392-433. [PMID: 26305243 PMCID: PMC6332049 DOI: 10.3390/molecules200815392] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/02/2015] [Accepted: 08/10/2015] [Indexed: 12/13/2022] Open
Abstract
Recently, research into the development of new antimicrobial agents has been driven by the increase in resistance to traditional antibiotics and Emerging Infectious Diseases. Antimicrobial peptides (AMPs) are promising candidates as alternatives to current antibiotics in the treatment and prevention of microbial infections. AMPs are produced by all known living species, displaying direct antimicrobial killing activity and playing an important role in innate immunity. To date, more than 2000 AMPs have been discovered and many of these exhibit broad-spectrum antibacterial, antiviral and anti-parasitic activity. Neglected tropical diseases (NTDs) are caused by a variety of pathogens and are particularly wide-spread in low-income and developing regions of the world. Alternative, cost effective treatments are desperately needed to effectively battle these medically diverse diseases. AMPs have been shown to be effective against a variety of NTDs, including African trypanosomes, leishmaniosis and Chagas disease, trachoma and leprosy. In this review, the potential of selected AMPs to successfully treat a variety of NTD infections will be critically evaluated.
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Targeting methicillin-resistant Staphylococcus aureus with short salt-resistant synthetic peptides. Antimicrob Agents Chemother 2014; 58:4113-22. [PMID: 24798285 DOI: 10.1128/aac.02578-14] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The seriousness of microbial resistance combined with the lack of new antimicrobials has increased interest in the development of antimicrobial peptides (AMPs) as novel therapeutics. In this study, we evaluated the antimicrobial activities of two short synthetic peptides, namely, RRIKA and RR. These peptides exhibited potent antimicrobial activity against Staphylococcus aureus, and their antimicrobial effects were significantly enhanced by addition of three amino acids in the C terminus, which consequently increased the amphipathicity, hydrophobicity, and net charge. Moreover, RRIKA and RR demonstrated a significant and rapid bactericidal effect against clinical and drug-resistant Staphylococcus isolates, including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate S. aureus (VISA), vancomycin-resistant S. aureus (VRSA), linezolid-resistant S. aureus, and methicillin-resistant Staphylococcus epidermidis. In contrast to many natural AMPs, RRIKA and RR retained their activity in the presence of physiological concentrations of NaCl and MgCl2. Both RRIKA and RR enhanced the killing of lysostaphin more than 1,000-fold and eradicated MRSA and VRSA isolates within 20 min. Furthermore, the peptides presented were superior in reducing adherent biofilms of S. aureus and S. epidermidis compared to results with conventional antibiotics. Our findings indicate that the staphylocidal effects of our peptides were through permeabilization of the bacterial membrane, leading to leakage of cytoplasmic contents and cell death. Furthermore, peptides were not toxic to HeLa cells at 4- to 8-fold their antimicrobial concentrations. The potent and salt-insensitive antimicrobial activities of these peptides present an attractive therapeutic candidate for treatment of multidrug-resistant S. aureus infections.
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Role of the LytSR two-component regulatory system in adaptation to cationic antimicrobial peptides in Staphylococcus aureus. Antimicrob Agents Chemother 2013; 57:3875-82. [PMID: 23733465 DOI: 10.1128/aac.00412-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Many host defense cationic antimicrobial peptides (HDPs) perturb the staphylococcal cell membrane (CM) and alter transmembrane potential (ΔΨ) as key parts of their lethal mechanism. Thus, a sense-response system for detecting and mediating adaptive responses to such stresses could impact organism survival; the Staphylococcus aureus LytSR two-component regulatory system (TCRS) may serve as such a ΔΨ sensor. One well-known target of this system is the lrgAB operon, which, along with the related cidABC operon, has been shown to be a regulator in the control of programmed cell death and lysis. We used an isogenic set of S. aureus strains: (i) UAMS-1, (ii) its isogenic ΔlytS and ΔlrgAB mutants, and (iii) plasmid-complemented ΔlytSR and ΔlrgAB mutants. The ΔlytS strain displayed significantly increased in vitro susceptibilities to all HDPs tested (neutrophil-derived human neutrophil peptide 1 [hNP-1], platelet-derived thrombin-induced platelet microbicidal proteins [tPMPs], and the tPMP-mimetic peptide RP-1), as well as to calcium-daptomycin (DAP), a cationic antimicrobial peptide (CAP). In contrast, the ΔlrgAB strain exhibited no significant changes in susceptibilities to these cationic peptides, indicating that although lytSR positively regulates transcription of lrgAB, increased HDP/CAP susceptibilities in the ΔlytS mutant were lrgAB independent. Further, parental UAMS-1 (but not the ΔlytS mutant) became more resistant to hNP-1 and DAP following pretreatment with carbonyl cyanide m-chlorophenylhydrazone (CCCP) (a CM-depolarizing agent). Of note, lytSR-dependent survival against CAP/HDP killing was not associated with changes in either surface positive charge, expression of mprF and dlt, or CM fluidity. The ΔlytS strain (but not the ΔlrgAB mutant) displayed a significant reduction in target tissue survival in an endocarditis model during DAP treatment. Collectively, these results suggest that the lytSR TCRS plays an important role in adaptive responses of S. aureus to CM-perturbing HDPs/CAPs, likely by functioning as a sense-response system for detecting subtle changes in ΔΨ.
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Di-alkylated paromomycin derivatives: Targeting the membranes of Gram positive pathogens that cause skin infections. Bioorg Med Chem 2013; 21:3624-31. [DOI: 10.1016/j.bmc.2013.03.046] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/08/2013] [Accepted: 03/11/2013] [Indexed: 11/20/2022]
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Okorochenkov SA, Zheltukhina GA, Nebol'sin VE. [Antimicrobial peptides: mode of action and perspectives of practical application]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2012; 58:131-43. [PMID: 22724354 DOI: 10.18097/pbmc20125802131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This review is devoted to antimicrobial peptides (AMP's) that demonstrate activity against bacteria, viruses and fungi. It considers structure and mechanism of AMP interaction with lipid membrane and intracellular targets of pathogens. Special attention is paid to modem state and perspectives of AMP practical application and also to approaches that increase efficacy and reduce toxicity of AMP by chemical modification of their structure.
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Celenza G, Segatore B, Setacci D, Bellio P, Brisdelli F, Piovano M, Garbarino JA, Nicoletti M, Perilli M, Amicosante G. In vitro antimicrobial activity of pannarin alone and in combination with antibiotics against methicillin-resistant Staphylococcus aureus clinical isolates. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2012; 19:596-602. [PMID: 22459282 DOI: 10.1016/j.phymed.2012.02.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/11/2012] [Accepted: 02/18/2012] [Indexed: 05/31/2023]
Abstract
The in vitro antimicrobial activities of pannarin, a depsidone isolated from lichens, collected in several Southern regions of Chile (including Antarctica), was evaluated alone and in combination with five therapeutically available antibiotics, using checkerboard microdilution assay against methicillin-resistant clinical isolates strains of Staphylococcus aureus. MIC(90), MIC(50), as well as MBC(90) and MBC(50), were evaluated. A moderate synergistic action was observed in combination with gentamicin, whilst antagonism was observed in combination with levofloxacin. All combinations with erythromycin were indifferent, whilst variability was observed for clindamycin and oxacillin combinations. Data from checkerboard assay were analysed and interpreted using the fractional inhibitory concentration index and the response surface approach using the ΔE model. Discrepancies were found between both methods for some combinations. In order to asses cellular lysis after exposure to pannarin, cell membrane permeability assay was performed. The treatment with pannarin produces bactericidal activity without significant calcein release, consistent with lack of lysis or even significant structural damage to the cytoplasmic membrane. Furthermore, pannarin shows low hemolytic activity and moderate cytotoxic effect on peripheral blood mononuclear cells. These findings suggest that the natural compound pannarin might be a good candidate for the individualization of novel templates for the development of new antimicrobial agents or combinations of drugs for chemotherapy.
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Affiliation(s)
- Giuseppe Celenza
- Department of Biomedical Sciences and Technologies, University of l'Aquila, L'Aquila, Italy.
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North SH, Wojciechowski J, Chu V, Taitt CR. Surface immobilization chemistry influences peptide-based detection of lipopolysaccharide and lipoteichoic acid. J Pept Sci 2012; 18:366-72. [PMID: 22565661 DOI: 10.1002/psc.2399] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 11/27/2011] [Accepted: 01/04/2012] [Indexed: 01/21/2023]
Abstract
Antimicrobial peptides (AMPs) have recently gained attention as potentially valuable diagnostic and therapeutic agents. The utilization of these peptides for diagnostic purposes relies on the ability to immobilize them on the surface of a detection platform in a predictable and reliable manner that facilitates target binding. The method for attachment of peptides to a solid support is guided by peptide length, amino acid composition, secondary structure, and the nature of the underlying substrate. While immobilization methods that target amine groups of amino acid sequences are widely used, they can result in heterogeneous conjugation at multiple sites on a peptide and have direct implications for peptide presentation and function. Using two types of commercial amine-reactive microtiter plates, we described the effects of analogous immobilization chemistries on the surface attachment of AMPs and their differential binding interaction with Gram-specific bacterial biomarkers, lipopolysaccharide and lipoteichoic acid. As might be expected, differences in overall binding affinities were noted when comparing AMPs immobilized on the two types of plates. However, the two-amine-targeted linking chemistries also affected the specificity of the attached peptides; lipopolysaccharide generally demonstrated a preference for peptides immobilized on one type of plate, while (when observed at all) lipoteichoic acid bound preferentially to AMPs immobilized on the other type of plate. These results demonstrate the potential for tuning not only the binding affinities but also the specificities of immobilized AMPs by simple alterations in linking strategy.
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Affiliation(s)
- Stella H North
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
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Abstract
The specific aminoacylation of the phospholipid phosphatidylglycerol (PG) with alanine or with lysine catalyzed by aminoacyl-phosphatidylglycerol synthases (aaPGS) was shown to render various organisms less susceptible to antibacterial agents. This study makes use of Pseudomonas aeruginosa chimeric mutant strains producing lysyl-phosphatidylglycerol (L-PG) instead of the naturally occurring alanyl-phosphatidylglycerol (A-PG) to study the resulting impact on bacterial resistance. Consequences of such artificial phospholipid composition were studied in the presence of an overall of seven antimicrobials (β-lactams, a lipopeptide antibiotic, cationic antimicrobial peptides [CAMPs]) to quantitatively assess the effect of A-PG substitution (with L-PG, L-PG and A-PG, increased A-PG levels). For the employed Gram-negative P. aeruginosa model system, an exclusive charge repulsion mechanism does not explain the attenuated antimicrobial susceptibility due to PG modification. Additionally, the specificity of nine orthologous aaPGS enzymes was experimentally determined. The newly characterized protein sequences allowed for the establishment of a significant group of A-PG synthase sequences which were bioinformatically compared to the related group of L-PG synthesizing enzymes. The analysis revealed a diverse origin for the evolution of A-PG and L-PG synthases, as the specificity of an individual enzyme is not reflected in terms of a characteristic sequence motif. This finding is relevant for future development of potential aaPGS inhibitors.
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Solano AGR, Pereira LDMCS, Leonel MDFV, Nunan EDA. Development of agar diffusion method for dosage of gramicidin. BRAZ J PHARM SCI 2011. [DOI: 10.1590/s1984-82502011000300014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gramicidin, an antimicrobial peptide active against Gram positive bacteria, is commonly used in pharmaceutical preparations for topical use. Considering that only the turbidimetric method has been described in the literature, the present study sought to develop and validate an agar diffusion method for the dosage of gramicidin. The method was developed and validated using the Kocuria rhizophila ATCC 9341 as a test microorganism. Two designs were used: a 3x3 parallel-line model, and a 5x1 standard curve. The validation demonstrated that the method follows the linear model (r²= 0.994), presenting a significant regression between the zone diameter of growth inhibition and the logarithm of the concentration within the range of 5 to 25.3 µg/mL. The results obtained for both designs were precise, having a relative standard deviation (R.S.D.) for intra-day precision of 0.81 for the 3x3 assay and 1.90 for the 5x1 assay. For the inter-day precision, the R.S.D. was 1.35 for the 3x3 and 2.64 for the 5x1. The accuracy was verified and results confirmed to be accurate, having a tolerance interval of 95%, which lay within permitted limits and appropriate trueness. In addition, the method was considered selective, with limit of detection and upper and lower limits of quantification of 2.00, 5.00 and 25.3 µg/mL, respectively. No difference in precision between the designs used in the agar diffusion method was evident (p>0.05). The method proved to be appropriate for the microbiological dosage of the raw material gramicidin.
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Okorochenkov SA, Zheltukhina GA, Nebol’sin VE. Antimicrobial peptides: the mode of action and perspectives of practical application. BIOCHEMISTRY MOSCOW-SUPPLEMENT SERIES B-BIOMEDICAL CHEMISTRY 2011. [DOI: 10.1134/s1990750811020120] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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C-terminal amino acids of alpha-melanocyte-stimulating hormone are requisite for its antibacterial activity against Staphylococcus aureus. Antimicrob Agents Chemother 2011; 55:1920-9. [PMID: 21282427 DOI: 10.1128/aac.00957-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Alpha-melanocyte-stimulating hormone (α-MSH) is an endogenous neuropeptide that is known for its anti-inflammatory and antipyretic activities. We recently demonstrated that α-MSH possesses staphylocidal activity and causes bacterial membrane damage. To understand the role of its amino acid sequences in the staphylocidal mechanism, in the present study we investigated the antimicrobial activities of different fragments of α-MSH, i.e., α-MSH(6-13), α-MSH(11-13), and α-MSH(1-5), and compared them with that of the entire peptide. Our results showed that peptides containing the C-terminal region of α-MSH, namely, α-MSH(6-13) and α-MSH(11-13), efficiently killed >90% of both methicillin-sensitive and -resistant Staphylococcus aureus cells in the micromolar range and ∼50% of these cells in the nanomolar range; their efficiency was comparable to that of the entire α-MSH, whereas the peptide containing the N-terminal region, α-MSH(1-5), was found to be ineffective against S. aureus. The antimicrobial activity of α-MSH and its C-terminal fragments was not affected by the presence of NaCl or even divalent cations such as Ca2+ and Mg2+. Similar to the case for the parent peptide, α-MSH(6-13) and α-MSH(11-13) also depolarized and permeabilized Staphylococcus cells (∼70 to 80% of the cells were depolarized and lysed after 2 h of peptide exposure at micromolar concentrations). Furthermore, scanning and transmission electron microscopy showed remarkable morphological and ultrastructural changes on S. aureus cell surface due to exposure to α-MSH-based peptides. Thus, our observations indicate that C-terminal fragments of α-MSH retain the antimicrobial activity of entire peptide and that their mechanism of action is similar to that of full-length peptide. These observations are important and are critical in the rational design of α-MSH-based therapeutics with optimal efficacy.
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Rodas PI, Contreras I, Mora GC. Salmonella enterica serovar Typhi has a 4.1 kb genetic island inserted within the sapABCDF operon that causes loss of resistance to the antimicrobial peptide protamine. J Antimicrob Chemother 2010; 65:1624-30. [PMID: 20551214 DOI: 10.1093/jac/dkq197] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVES To investigate the association between the presence of a genetic island inserted within the sapABCDF operon of Salmonella Typhi and the susceptibility to antimicrobial peptides. METHODS Genetics and bioinformatics approaches were used to study the genomic organization of the sap operon of Salmonella Typhi and several serovars of Salmonella enterica. PCR was used to confirm the information obtained from these analyses. Deletion of the entire genetic island of Salmonella Typhi was achieved by the red swap method. RT-PCR amplification and antimicrobial peptide susceptibility tests were used to evaluate expression of the sap genes and bacterial resistance to protamine. RESULTS Inspection of the genomes of Salmonella Typhi and 10 serovars of Salmonella enterica showed an insertion of a genetic island located between the sapB and sapC genes of the sap operon. This genetic element was referred to as GICT18/1. Unlike Salmonella Typhimurium, the bacterial susceptibility to protamine is increased in Salmonella Typhi wild-type. Deletion of GICT18/1 resulted in protamine susceptibility levels similar to those of Salmonella Typhimurium, suggesting that restoration of the sap operon occurred in the Salmonella Typhi Delta GICT18-1 mutant strain. RT-PCR experiments supported this assumption because an amplicon containing a fragment of sapD-sapF was detected in Salmonella Typhi Delta GICT18/1, whereas it was not detected in Salmonella Typhi wild-type. CONCLUSIONS The presence of GICT18/1 seems to be a natural feature of Salmonella Typhi. This genetic island is found only in 10 out of 32 Salmonella enterica serovars included in this study. Removal of GICT18/1 has an impact in the susceptibility of Salmonella Typhi to the antimicrobial peptide protamine.
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Affiliation(s)
- Paula I Rodas
- Programa de Doctorado en Bioquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
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Pränting M, Andersson DI. Mechanisms and physiological effects of protamine resistance in Salmonella enterica serovar Typhimurium LT2. J Antimicrob Chemother 2010; 65:876-87. [DOI: 10.1093/jac/dkq059] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Attia AS, Benson MA, Stauff DL, Torres VJ, Skaar EP. Membrane damage elicits an immunomodulatory program in Staphylococcus aureus. PLoS Pathog 2010; 6:e1000802. [PMID: 20300601 PMCID: PMC2837406 DOI: 10.1371/journal.ppat.1000802] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 02/03/2010] [Indexed: 01/29/2023] Open
Abstract
The Staphylococcus aureus HrtAB system is a hemin-regulated ABC transporter composed of an ATPase (HrtA) and a permease (HrtB) that protect S. aureus against hemin toxicity. S. aureus strains lacking hrtA exhibit liver-specific hyper-virulence and upon hemin exposure over-express and secrete immunomodulatory factors that interfere with neutrophil recruitment to the site of infection. It has been proposed that heme accumulation in strains lacking hrtAB is the signal which triggers S. aureus to elaborate this anti-neutrophil response. However, we report here that S. aureus strains expressing catalytically inactive HrtA do not elaborate the same secreted protein profile. This result indicates that the physical absence of HrtA is responsible for the increased expression of immunomodulatory factors, whereas deficiencies in the ATPase activity of HrtA do not contribute to this process. Furthermore, HrtB expression in strains lacking hrtA decreases membrane integrity consistent with dysregulated permease function. Based on these findings, we propose a model whereby hemin-mediated over-expression of HrtB in the absence of HrtA damages the staphylococcal membrane through pore formation. In turn, S. aureus senses this membrane damage, triggering the increased expression of immunomodulatory factors. In support of this model, wildtype S. aureus treated with anti-staphylococcal channel-forming peptides produce a secreted protein profile that mimics the effect of treating ΔhrtA with hemin. These results suggest that S. aureus senses membrane damage and elaborates a gene expression program that protects the organism from the innate immune response of the host. Staphylococcus aureus infects almost every tissue within the human body utilizing a range of virulence factors to combat host defenses. The expression of these virulence factors is a tightly regulated process; however, the signals sensed by S. aureus during infection remain elusive. It has been hypothesized that heme toxicity is a signal sensed by S. aureus during infection. This hypothesis is based on the observation that S. aureus mutants which are incapable of relieving heme-toxicity due to inactivation of the ATPase HrtA elicit an immunomodulatory program that interferes with neutrophil recruitment to the site of infection. In keeping with this, S. aureus hrtA mutants exhibit liver-specific hypervirulence. Herein, we provide evidence for an alternative model to explain the hypervirulent phenotype of S. aureus ΔhrtA. We demonstrate that instead of accumulation of heme toxicity being the trigger for the observed immunomodulatory program, dysregulated pore formation caused by the HrtB permease triggers the anti-neutrophil response. In support of this model, over-expression of HrtB in wildtype S. aureus or exposing S. aureus to channel-forming antimicrobial peptides induces a similar immunomodulatory program. Our work provides evidence that S. aureus senses membrane damage and induces an immunomodulatory circuit that helps the pathogen evade immune-mediated clearance.
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Affiliation(s)
- Ahmed S. Attia
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Meredith A. Benson
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Devin L. Stauff
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Eric P. Skaar
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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Joanne P, Falord M, Chesneau O, Lacombe C, Castano S, Desbat B, Auvynet C, Nicolas P, Msadek T, El Amri C. Comparative study of two plasticins: specificity, interfacial behavior, and bactericidal activity. Biochemistry 2009; 48:9372-83. [PMID: 19711984 DOI: 10.1021/bi901222p] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A comparative study was designed to evaluate the staphylococcidal efficiency of two sequence-related plasticins from the dermaseptin superfamily we screened previously. Their bactericidal activities against Staphylococcus aureus as well as their chemotactic potential were investigated. The impact of the GraS/GraR two-component system involved in regulating resistance to cationic antimicrobial peptides (CAMPs) was evaluated. Membrane disturbing activity was quantified by membrane depolarization assays using the diS-C3 probe and by membrane integrity assays measuring beta-galactosidase activity with recombinant strain ST1065 reflecting compromised membranes and cytoplasmic leakage. Interactions of plasticins with membrane models composed of either zwitterionic lipids mimicking the S. aureus membrane of CAMP-resistant strains or anionic lipids mimicking the negative charge-depleted membrane of CAMP-sensitive strains were analyzed by jointed Brewster angle microscopy (BAM), polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and differential scanning calorimetry (DSC) to yield detailed information about the macroscopic interfacial organization, in situ conformation, orientation of the peptides at the lipid-solvent interface, and lipid-phase disturbance. We clearly found evidence of distinct interfacial behaviors of plasticins we linked to the distribution of charges along the peptides and structural interconversion properties at the membrane interface. Our results also suggest that amidation might play a key role in GraS/GraR-mediated CAMP sensing at the bacterial surface.
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Affiliation(s)
- Pierre Joanne
- Universite Pierre et Marie Curie, ER3-Biogenese des signaux peptidiques, 75251 Paris Cedex 05, France
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Lesmes LP, Bohorquez MY, Carreño LF, Patarroyo ME, Lozano JM. A C-terminal cationic fragment derived from an arginine-rich peptide exhibits in vitro antibacterial and anti-plasmodial activities governed by its secondary structure properties. Peptides 2009; 30:2150-60. [PMID: 19698754 DOI: 10.1016/j.peptides.2009.08.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/11/2009] [Accepted: 08/12/2009] [Indexed: 10/20/2022]
Abstract
The differential in vitro antimicrobial activity of a 12-residue-long arginine-rich peptide derived from protamine was examined against bacterial and parasite microbes. A design of discrete peptide fragments based on the thermolysin-digestion map allowed us to propose three peptide fragments to be further assessed regarding their biological and secondary structural properties. Peptide structure allowed designing three arginine-rich fragments. All peptide fragments were assessed regarding their antimicrobial activity against Gram-positive and Gram-negative bacteria and a human malaria strain. Qualitative and quantitative assays carried out for determining all peptides' antibacterial activity at different concentration levels included radial diffusion and a time-controlled technique. Tests demonstrated that all assessed molecules inhibited invasion of Plasmodium falciparum parasites to human red blood cells. Cytolytic activity of the parent protamine peptide was completely abolished by strategically fragmenting its aminoacid sequence. Remarkably, the cationic C-fragment exhibited stronger biological activity than its parent peptide. Interestingly, the peptide fragment denoted as 2077 displays a typical alpha-helix profile according to its CD spectrum. The results support proposing the protamine C-terminal fragment as a potential new antimicrobial peptide.
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Affiliation(s)
- Liliana Patricia Lesmes
- Fundación Instituto de Inmunología de Colombia, Bogotá DC, Colombia and Universidad del Rosario, Bogotá DC, Colombia
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Abstract
There is widespread acceptance that cationic antimicrobial peptides, apart from their membrane-permeabilizing/disrupting properties, also operate through interactions with intracellular targets, or disruption of key cellular processes. Examples of intracellular activity include inhibition of DNA and protein synthesis, inhibition of chaperone-assisted protein folding and enzymatic activity, and inhibition of cytoplasmic membrane septum formation and cell wall synthesis. The purpose of this minireview is to question some widely held views about intracellular-targeting antimicrobial peptides. In particular, I focus on the relative contributions of intracellular targeting and membrane disruption to the overall killing strategy of antimicrobial peptides, as well as on mechanisms whereby some peptides are able to translocate spontaneously across the plasma membrane. Currently, there are no more than three peptides that have been convincingly demonstrated to enter microbial cells without the involvement of stereospecific interactions with a receptor/docking molecule and, once in the cell, to interfere with cellular functions. From the limited data currently available, it seems unlikely that this property, which is isolated in particular peptide families, is also shared by the hundreds of naturally occurring antimicrobial peptides that differ in length, amino acid composition, sequence, hydrophobicity, amphipathicity, and membrane-bound conformation. Microbial cell entry and/or membrane damage associated with membrane phase/transient pore or long-lived transitions could be a feature common to intracellular-targeting antimicrobial peptides and mammalian cell-penetrating peptides that have an overrepresentation of one or two amino acids, i.e. Trp and Pro, His, or Arg. Differences in membrane lipid composition, as well as differential lipid recruitment by peptides, may provide a basis for microbial cell killing on one hand, and mammalian cell passage on the other.
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Affiliation(s)
- Pierre Nicolas
- Biogenèse des Signaux Peptidiques, ER3-UPMC, Université Pierre et Marie Curie, Paris, France.
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Shireen T, Venugopal SK, Ghosh D, Gadepalli R, Dhawan B, Mukhopadhyay K. In vitro antimicrobial activity of alpha-melanocyte stimulating hormone against major human pathogen Staphylococcus aureus. Peptides 2009; 30:1627-35. [PMID: 19560499 DOI: 10.1016/j.peptides.2009.06.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 06/17/2009] [Accepted: 06/18/2009] [Indexed: 10/20/2022]
Abstract
Alpha-melanocyte stimulating hormone (alpha-MSH) is an endogenous anti-inflammatory peptide reported to possess antimicrobial properties, however their role as antibacterial peptides is yet to be established. In the present study, we examined in vitro antibacterial activity of alpha-MSH against S. aureus strain ISP479C and several methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) S. aureus strains. Antibacterial activity was examined by varying several parameters, viz., bacterial cell densities, growth phase, pH, salt concentration, and temperature. Antibacterial activity was also examined in complex biomatrices of rat whole blood, plasma and serum as well as in biofilm form of bacteria. Our results showed that alpha-MSH possessed significant and rapid antibacterial activity against all the studied strains including MRSA (84% strains were killed on exposure to 12 microM of alpha-MSH for 2h). pH change from 7.4 to 4 increased alpha-MSH staphylocidal activity against ISP479C by 21%. Antibacterial activity of alpha-MSH was dependent on bacterial cell density and independent of growth phase. Moreover, antimicrobial activity was retained when alpha-MSH was placed into whole blood, plasma, and serum. Most importantly, alpha-MSH exhibited antibacterial activity against staphylococcal biofilms. Multiple membrane permeabilization assays suggested that membrane damage was, at least in part, a major mechanism of staphylocidal activity of alpha-MSH. Collectively the above findings suggest that alpha-MSH could be a promising candidate of a novel class of antimicrobial agents.
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Mukhopadhyay K, Whitmire W, Xiong YQ, Molden J, Jones T, Peschel A, Staubitz P, Adler-Moore J, McNamara PJ, Proctor RA, Yeaman MR, Bayer AS. In vitro susceptibility of Staphylococcus aureus to thrombin-induced platelet microbicidal protein-1 (tPMP-1) is influenced by cell membrane phospholipid composition and asymmetry. MICROBIOLOGY-SGM 2007; 153:1187-1197. [PMID: 17379728 DOI: 10.1099/mic.0.2006/003111-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Thrombin-induced platelet microbicidal proteins (e.g. tPMP-1) are small cationic peptides released from mammalian platelets. As the cytoplasmic membrane (CM) is a primary target of tPMPs, distinct CM characteristics are likely to affect the cells' susceptibility profiles. In Staphylococcus aureus, CM surface charge and hydrophobicity are principally determined by the content and distribution of its three major phospholipid (PL) constituents: negatively charged phosphatidylglycerol (PG) and cardiolipin (CL) and positively charged lysyl-PG (LPG). PL composition profiles, and inner vs outer CM leaflet PL distributions, were compared in an isogenic tPMP-susceptible (tPMP(S)) and -resistant (tPMP(R)) S. aureus strain pair (ISP479C vs ISP479R respectively). All PLs were asymmetrically distributed between the outer and inner CM leaflets in both strains. However, in ISP479R, the outer CM leaflet content of LPG was significantly increased vs ISP479C (27.3+/-11.0 % vs 18.6+/-7.0 % respectively; P=0.05). This observation correlated with reduced binding of the cationic proteins cytochrome c, poly-L-lysine, tPMP-1 and the tPMP-1-mimetic peptide, RP1, to tPMP-1(R) whole cells and to model liposomal CMs with LPG content and distribution similar to that of tPMP-1(R) strains. Collectively, selected CM parameters correlated with reduced staphylocidal capacities of tPMP-1 against certain S. aureus strains, including relative increases in outer CM leaflet positive charge and reduced surface binding of cationic molecules. These findings offer new insights into mechanisms of antimicrobial peptide susceptibility and resistance in S. aureus.
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Affiliation(s)
- Kasturi Mukhopadhyay
- The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - William Whitmire
- The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Yan Q Xiong
- The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- The Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA, USA
- The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Jaime Molden
- The Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA, USA
| | - Tiffanny Jones
- The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Andreas Peschel
- Cellular and Molecular Microbiology, Medical Microbiology and Hygiene, University of Tübingen, Tübingen, Germany
| | - Petra Staubitz
- Cellular and Molecular Microbiology, Medical Microbiology and Hygiene, University of Tübingen, Tübingen, Germany
| | - Jill Adler-Moore
- Department of Microbiology, California State Polytechnical State University-Pomona, Pomona, CA, USA
| | - Peter J McNamara
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI, USA
| | - Richard A Proctor
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI, USA
| | - Michael R Yeaman
- The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- The Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA, USA
- The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Arnold S Bayer
- The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- The Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA, USA
- The LA Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
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Failures in clinical treatment of Staphylococcus aureus Infection with daptomycin are associated with alterations in surface charge, membrane phospholipid asymmetry, and drug binding. Antimicrob Agents Chemother 2007; 52:269-78. [PMID: 17954690 DOI: 10.1128/aac.00719-07] [Citation(s) in RCA: 251] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Increasingly frequent reports have described the in vivo loss of daptomycin susceptibility in association with clinical treatment failures. The mechanism(s) of daptomycin resistance is not well understood. We studied an isogenic set of Staphylococcus aureus isolates from the bloodstream of a daptomycin-treated patient with recalcitrant endocarditis in which serial strains exhibited decreasing susceptibility to daptomycin. Since daptomycin is a membrane-targeting lipopeptide, we compared a number of membrane parameters in the initial blood isolate (parental) with those in subsequent daptomycin-resistant strains obtained during treatment. In comparison to the parental strain, resistant isolates demonstrated (i) enhanced membrane fluidity, (ii) increased translocation of the positively charged phospholipid lysyl-phosphotidylglycerol to the outer membrane leaflet, (iii) increased net positive surface charge (P < 0.05 versus the parental strain), (iv) reduced susceptibility to daptomycin-induced depolarization, permeabilization, and autolysis (P < 0.05 versus the parental strain), (v) significantly lower surface binding of daptomycin (P < 0.05 versus the parental strain), and (vi) increased cross-resistance to the cationic antimicrobial host defense peptides human neutrophil peptide 1 (hNP-1) and thrombin-induced platelet microbicidal protein 1 (tPMP-1). These data link distinct changes in membrane structure and function with in vivo development of daptomycin resistance in S. aureus. Moreover, the cross-resistance to hNP-1 and tPMP-1 may also impact the capacity of these daptomycin-resistant organisms to be cleared from sites of infection, particularly endovascular foci.
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The role of released ATP in killing Candida albicans and other extracellular microbial pathogens by cationic peptides. Purinergic Signal 2007; 3:91-7. [PMID: 18404422 PMCID: PMC2096768 DOI: 10.1007/s11302-006-9040-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 05/30/2006] [Indexed: 02/07/2023] Open
Abstract
A unifying theme common to the action of many cationic peptides that display lethal activities against microbial pathogens is their specific action at microbial membranes that results in selective loss of ions and small nucleotides chiefly ATP. One model cationic peptide that induces non-lytic release of ATP from the fungal pathogen Candida albicans is salivary histatin 5 (Hst 5). The major characteristic of Hst 5-induced ATP release is that it occurs rapidly while cells are still metabolically active and have polarized membranes, thus precluding cell lysis as the means of release of ATP. Other cationic peptides that induce selective release of ATP from target microbes are lactoferricin, human neutrophil defensins, bactenecin, and cathelicidin peptides. The role of released extracellular ATP induced by cationic peptides is not known, but localized increases in extracellular ATP concentration may serve to potentiate cell killing, facilitate further peptide uptake, or function as an additional signal to activate the host innate immune system at the site of infection.
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Podda E, Benincasa M, Pacor S, Micali F, Mattiuzzo M, Gennaro R, Scocchi M. Dual mode of action of Bac7, a proline-rich antibacterial peptide. Biochim Biophys Acta Gen Subj 2006; 1760:1732-40. [PMID: 17059867 DOI: 10.1016/j.bbagen.2006.09.006] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 09/06/2006] [Accepted: 09/08/2006] [Indexed: 10/24/2022]
Abstract
Proline-rich peptides are a unique group of antimicrobial peptides that exert their activity selectively against Gram-negative bacteria through an apparently non-membranolytic mode of action that is not yet well understood. We have investigated the mechanism underlying the antibacterial activity of the proline-rich cathelicidin Bac7 against Salmonella enterica and Escherichia coli. The killing and membrane permeabilization kinetics as well as the cellular localization were assessed for the fully active N-terminal fragment Bac7(1-35), its all-D enantiomer and for differentially active shortened fragments. At sub-micromolar concentrations, Bac7(1-35) rapidly killed bacteria by a non-lytic, energy-dependent mechanism, whereas its D-enantiomer was inactive. Furthermore, while the L-enantiomer was rapidly internalized into bacterial cells, the D-enantiomer was virtually excluded. At higher concentrations (>or=64 microM), both L- and D-Bac7(1-35) were instead able to kill bacteria also via a lytic mechanism. Overall, these results suggest that Bac7 may inactivate bacteria via two different modes of action depending on its concentration: (i) at near-MIC concentrations via a mechanism based on a stereospecificity-dependent uptake that is likely followed by its binding to an intracellular target, and (ii) at concentrations several times the MIC value, via a non-stereoselective, membranolytic mechanism.
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Affiliation(s)
- Elena Podda
- Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, Via Giorgieri 1, 34127 Trieste, Italy
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35
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Xiong YQ, Bayer AS, Elazegui L, Yeaman MR. A synthetic congener modeled on a microbicidal domain of thrombin- induced platelet microbicidal protein 1 recapitulates staphylocidal mechanisms of the native molecule. Antimicrob Agents Chemother 2006; 50:3786-92. [PMID: 16954324 PMCID: PMC1635186 DOI: 10.1128/aac.00038-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thrombin-induced platelet microbicidal protein 1 (tPMP-1) is a staphylocidal peptide released by activated platelets. This peptide initiates its microbicidal activity by membrane permeabilization, with ensuing inhibition of intracellular macromolecular synthesis. RP-1 is a synthetic congener modeled on the C-terminal microbicidal alpha-helix of tPMP-1. This study compared the staphylocidal mechanisms of RP-1 with those of tPMP-1, focusing on isogenic tPMP-1-susceptible (ISP479C) and -resistant (ISP479R) Staphylococcus aureus strains for the following quantitative evaluations: staphylocidal efficacy; comparative MIC; membrane permeabilization (MP) and depolarization; and DNA, RNA, and protein synthesis. Although the proteins had similar MICs, RP-1 caused significant killing of ISP479C (<50% survival), correlating with extensive MP (>95%) and inhibition of DNA and RNA synthesis (>90%), versus substantially reduced killing of ISP479R (>80% survival), with less MP (55%) and less inhibition of DNA or RNA synthesis (70 to 80%). Interestingly, RP-1-induced protein synthesis inhibition was equivalent in both strains. RP-1 did not depolarize the cell membrane and caused a relatively short postexposure growth inhibition. These data closely parallel those previously reported for tPMP-1 against this strain set and exemplify how synthetic molecules can be engineered to reflect structure-activity relationships of functional domains in native host defense effector molecules.
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Affiliation(s)
- Yan Q Xiong
- Department of Medicine, Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, 1124 West Carson Street, RB-2, Room 231, Torrance, CA 90502, USA.
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36
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Abstract
Native antimicrobial peptides and proteins represent bridges between innate and adaptive immunity in mammals. On the one hand they possess direct bacterial killing properties, partly by disintegrating bacterial membranes, and some also by inhibiting functions of intracellular biopolymers. On the other, native antimicrobial peptides and proteins upregulate the host defense as chemoattractants or by various additional immunostimulatory effects. Structure-activity relationship studies indicate that residues responsible for the activities on bacterial membranes or for the secondary functions do not perfectly overlap. In reality, in spite of the relatively short size (18-20 amino acid residues) of some of these molecules, the functional domains can frequently be separated, with the cell-penetrating fragments located at the C-termini and the protein binding domains found upstream. As a cumulative effect, multifunctional and target-specific (agonist or antagonist) antimicrobial peptides and proteins interfere with more than one bacterial function at low concentrations, eliminating toxicity concerns of the earlier generations of antibacterial peptides observed in the clinical setting.
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37
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Xiong YQ, Mukhopadhyay K, Yeaman MR, Adler-Moore J, Bayer AS. Functional interrelationships between cell membrane and cell wall in antimicrobial peptide-mediated killing of Staphylococcus aureus. Antimicrob Agents Chemother 2005; 49:3114-21. [PMID: 16048912 PMCID: PMC1196293 DOI: 10.1128/aac.49.8.3114-3121.2005] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Perturbation of the Staphylococcus aureus cytoplasmic membrane (CM) is felt to play a key role in the microbicidal mechanism of many antimicrobial peptides (APs). However, it is not established whether membrane permeabilization (MP) alone is sufficient to kill susceptible staphylococci or if the cell wall (CW) and/or intracellular targets contribute to AP-induced lethality. We hypothesized that the relationships between MP and killing may differ for distinct APs. In this study, we investigated the association between AP-induced MP and lethality in S. aureus whole cells versus CW-free protoplasts, and in comparison to the MP of liposomes modeled after whole CMs in terms of phospholipid composition, fluidity and charge. Four APs with different structure-activity relationships were examined: thrombin-induced platelet microbicidal protein 1 (tPMP-1), human neutrophil protein 1 (hNP-1), gramicidin D, and polymyxin B. MP was quantified fluorometrically by calcein release. All APs tested, except polymyxin B, caused concentration-dependent MP and killing of whole cells, but not of protoplasts. The reduced AP susceptibility of protoplasts was associated with increased cardiolipin and lysyl-phosphatidylglycerol content and reduced fluidity of their CMs. However, liposomal MP induced by tPMP-1, hNP-1, and gramicidin D paralleled that of whole cells. Collectively, these results indicate that (i) structurally distinct APs likely exert their staphylocidal effects by differing mechanisms, (ii) MP is not the sole event leading to AP-induced staphylocidal activity, (iii) a complex interrelationship exists between the CM and CW in AP-induced killing, and (iv) liposomes modeled upon whole cell or protoplast CMs can recapitulate the respective susceptibilities to killing by distinct APs.
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Affiliation(s)
- Yan Q Xiong
- LA Biomedical Research Institute at Harbor-UCLA St. John's Cardiovascular Research Center, RB-2, 1124 West Carson Street, Torrance, CA 90502, USA.
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38
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Abstract
Antimicrobial peptides have been isolated and characterized from tissues and organisms representing virtually every kingdom and phylum, ranging from prokaryotes to humans. Yet, recurrent structural and functional themes in mechanisms of action and resistance are observed among peptides of widely diverse source and composition. Biochemical distinctions among the peptides themselves, target versus host cells, and the microenvironments in which these counterparts convene, likely provide for varying degrees of selective toxicity among diverse antimicrobial peptide types. Moreover, many antimicrobial peptides employ sophisticated and dynamic mechanisms of action to effect rapid and potent activities consistent with their likely roles in antimicrobial host defense. In balance, successful microbial pathogens have evolved multifaceted and effective countermeasures to avoid exposure to and subvert mechanisms of antimicrobial peptides. A clearer recognition of these opposing themes will significantly advance our understanding of how antimicrobial peptides function in defense against infection. Furthermore, this understanding may provide new models and strategies for developing novel antimicrobial agents, that may also augment immunity, restore potency or amplify the mechanisms of conventional antibiotics, and minimize antimicrobial resistance mechanisms among pathogens. From these perspectives, the intention of this review is to illustrate the contemporary structural and functional themes among mechanisms of antimicrobial peptide action and resistance.
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Affiliation(s)
- Michael R Yeaman
- Division of Infectious Diseases, Harbor-University of California Los Angeles Medical Center, Torrance, California, USA.
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