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Ghovanloo MR, Goodchild SJ, Ruben PC. Cannabidiol increases gramicidin current in human embryonic kidney cells: An observational study. PLoS One 2022; 17:e0271801. [PMID: 35913948 PMCID: PMC9342711 DOI: 10.1371/journal.pone.0271801] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 07/07/2022] [Indexed: 02/02/2023] Open
Abstract
Gramicidin is a monomeric protein that is thought to non-selectively conduct cationic currents and water. Linear gramicidin is considered an antibiotic. This function is considered to be mediated by the formation of pores within the lipid membrane, thereby killing bacterial cells. The main non-psychoactive active constituent of the cannabis plant, cannabidiol (CBD), has recently gained interest, and is proposed to possess various potential therapeutic properties, including being an antibiotic. We previously determined that CBD’s activity on ion channels could be, in part, mediated by altering membrane biophysical properties, including elasticity. In this study, our goal was to determine the empirical effects of CBD on gramicidin currents in human embryonic kidney (HEK) cells, seeking to infer potential direct compound-protein interactions. Our results indicate that gramicidin, when applied to the extracellular HEK cell membrane, followed by CBD perfusion, increases the gramicidin current.
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Affiliation(s)
- Mohammad-Reza Ghovanloo
- Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, BC, Canada
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Samuel J. Goodchild
- Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, BC, Canada
| | - Peter C. Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
- * E-mail:
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2
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Buta A, Nazaruk E, Dziubak D, Szewczyk A, Bilewicz R. Properties of electrode-supported lipid cubic mesophase films with embedded gramicidin A: structure and ion-transport studies. Bioelectrochemistry 2022; 144:108042. [PMID: 34942573 DOI: 10.1016/j.bioelechem.2021.108042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022]
Abstract
The lipid cubic phase (LCP) is a nanomaterial composed of water channels surrounded by lipid bilayers. LCPs are stable at room temperature and are biocompatible. These features make the lipid cubic phases similar to biological membranes, and hence, are favorable for embedding membrane proteins. We show that the monoolein cubic phase deposited on the electrode forms a 3D lipid bilayer film convenient for electrochemical investigations of membrane proteins. In this research, we studied the effect of embedding an ionophoric peptide, gramicidin A (gA), on the structure and properties of the LCP film. The phase identity and structural parameters of the gramicidin-doped phase were characterized by small-angle X-ray scattering (SAXS). The potassium ion transport through the film were studied by electroanalytical methods: alternating current voltammetry (ACV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Increased values for the current of the gramicidin-doped cubic phase compared to the empty cubic phase and changes of the EIS parameters confirmed that the peptide remained in the film in its active dimeric form. Our results show that the LCP can be considered a suitable 3D biomimetic film for the investigation of ion channels and other transporting membrane proteins, and for their application in electrochemical sensors.
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Affiliation(s)
- Aleksandra Buta
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Ewa Nazaruk
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Damian Dziubak
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Renata Bilewicz
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
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3
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The Nonribosomal Peptide Valinomycin: From Discovery to Bioactivity and Biosynthesis. Microorganisms 2021; 9:microorganisms9040780. [PMID: 33917912 PMCID: PMC8068249 DOI: 10.3390/microorganisms9040780] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/03/2021] [Accepted: 04/07/2021] [Indexed: 12/17/2022] Open
Abstract
Valinomycin is a nonribosomal peptide that was discovered from Streptomyces in 1955. Over the past more than six decades, it has received continuous attention due to its special chemical structure and broad biological activities. Although many research papers have been published on valinomycin, there has not yet been a comprehensive review that summarizes the diverse studies ranging from structural characterization, biogenesis, and bioactivity to the identification of biosynthetic gene clusters and heterologous biosynthesis. In this review, we aim to provide an overview of valinomycin to address this gap, covering from 1955 to 2020. First, we introduce the chemical structure of valinomycin together with its chemical properties. Then, we summarize the broad spectrum of bioactivities of valinomycin. Finally, we describe the valinomycin biosynthetic gene cluster and reconstituted biosynthesis of valinomycin. With that, we discuss possible opportunities for the future research and development of valinomycin.
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4
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Xin P, Zhao L, Mao L, Xu L, Hou S, Kong H, Fang H, Zhu H, Jiang T, Chen CP. Effect of charge status on the ion transport and antimicrobial activity of synthetic channels. Chem Commun (Camb) 2020; 56:13796-13799. [DOI: 10.1039/d0cc05730d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The charge status of channels formed by pillararene–gramicidin hybrid molecules has a significant impact on their trans-membrane transport properties, membrane-association abilities and antimicrobial activities.
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5
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Haoyang W, Zhang M, Hou J. Deformylated Gramicidin A and Its Derivatives Showing High Antimicrobial Activity and Low Hemolytic Toxicity. CHINESE J CHEM 2018. [DOI: 10.1002/cjoc.201800451] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Wei‐Wei Haoyang
- Department of ChemistryFudan University 220 Handan Road, Shanghai 200433 China
| | - Min Zhang
- Department of ChemistryFudan University 220 Handan Road, Shanghai 200433 China
| | - Jun‐Li Hou
- Department of ChemistryFudan University 220 Handan Road, Shanghai 200433 China
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7
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Mishra B, Reiling S, Zarena D, Wang G. Host defense antimicrobial peptides as antibiotics: design and application strategies. Curr Opin Chem Biol 2017; 38:87-96. [PMID: 28399505 PMCID: PMC5494204 DOI: 10.1016/j.cbpa.2017.03.014] [Citation(s) in RCA: 207] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/21/2017] [Accepted: 03/22/2017] [Indexed: 12/16/2022]
Abstract
This review deals with the design and application strategies of new antibiotics based on naturally occurring antimicrobial peptides (AMPs). The initial candidate can be designed based on three-dimensional structure or selected from a library of peptides from natural or laboratory sources followed by optimization via structure-activity relationship studies. There are also advanced application strategies such as induction of AMP expression from host cells by various factors (e.g., metals, amino acids, vitamin D and sunlight), the use of engineered probiotic bacteria to deliver peptides, the design of prodrug and peptide conjugates to improve specific targeting. In addition, combined uses of newly developed AMPs with existing antimicrobial agents may provide a practical avenue for effective management of antibiotic-resistant bacteria (superbugs), including biofilms. Finally, we highlight AMPs already in use or under clinical trials.
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Affiliation(s)
- Biswajit Mishra
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - Scott Reiling
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - D Zarena
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA; Department of Physics, JNTUA College of Engineering, Anantapur 515002, India
| | - Guangshun Wang
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA.
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Xin P, Sun Y, Kong H, Wang Y, Tan S, Guo J, Jiang T, Dong W, Chen CP. A unimolecular channel formed by dual helical peptide modified pillar[5]arene: correlating transmembrane transport properties with antimicrobial activity and haemolytic toxicity. Chem Commun (Camb) 2017; 53:11492-11495. [DOI: 10.1039/c7cc06697j] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Five unimolecular channels with different lengths are presented. The varying length of these channels has significant impact on their transport properties.
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Affiliation(s)
- Pengyang Xin
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
| | - Yonghui Sun
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
| | - Huiyuan Kong
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
| | - Yaodong Wang
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
| | - Si Tan
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
| | - Jingjing Guo
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
| | - Tao Jiang
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
| | - Wenpei Dong
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
| | - Chang-Po Chen
- Henan Engineering Laboratory of Chemical Pharmaceuticals & Biomedical Materials
- Henan Key Laboratory of Organic Functional Molecule and Drug Innovation
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals
- Key Laboratory of Green Chemical Media and Reactions
- Ministry of Education
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9
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Carrasco LDDM, Bertolucci R, Ribeiro RT, Sampaio JLM, Carmona-Ribeiro AM. Cationic Nanostructures against Foodborne Pathogens. Front Microbiol 2016; 7:1804. [PMID: 27881979 PMCID: PMC5101191 DOI: 10.3389/fmicb.2016.01804] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 10/27/2016] [Indexed: 11/13/2022] Open
Affiliation(s)
- Letícia Dias de Melo Carrasco
- Laboratório de Biocolóides, Departamento de Bioquímica, Instituto de Química, Universidade de São PauloSão Paulo, Brazil; Laboratório de Microbiologia, Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São PauloSão Paulo, Brazil
| | - Ronaldo Bertolucci
- Laboratório de Biocolóides, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo São Paulo, Brazil
| | - Rodrigo T Ribeiro
- Laboratório de Biocolóides, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo São Paulo, Brazil
| | - Jorge L M Sampaio
- Laboratório de Microbiologia, Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo São Paulo, Brazil
| | - Ana M Carmona-Ribeiro
- Laboratório de Biocolóides, Departamento de Bioquímica, Instituto de Química, Universidade de São PauloSão Paulo, Brazil; Laboratório de Microbiologia, Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São PauloSão Paulo, Brazil
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10
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Li W, O'Brien-Simpson NM, Tailhades J, Pantarat N, Dawson RM, Otvos L, Reynolds EC, Separovic F, Hossain MA, Wade JD. Multimerization of a Proline-Rich Antimicrobial Peptide, Chex-Arg20, Alters Its Mechanism of Interaction with the Escherichia coli Membrane. ACTA ACUST UNITED AC 2016; 22:1250-8. [PMID: 26384569 DOI: 10.1016/j.chembiol.2015.08.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/28/2015] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
A3-APO, a de novo designed branched dimeric proline-rich antimicrobial peptide (PrAMP), is highly effective against a variety of in vivo bacterial infections. We undertook a selective examination of the mechanism for the Gram-negative Escherichia coli bacterial membrane interaction of the monomer (Chex-Arg20), dimer (A3-APO), and tetramer (A3-APO disulfide-linked dimer). All three synthetic peptides were effective at killing E. coli. However, the tetramer was 30-fold more membrane disruptive than the dimer while the monomer showed no membrane activity. Using flow cytometry and high-resolution fluorescent microscopy, it was observed that dimerization and tetramerization of the Chex-Arg20 monomer led to an alteration in the mechanism of action from non-lytic/membrane hyperpolarization to membrane disruption/depolarization. Our findings show that the membrane interaction and permeability of Chex-Arg20 was altered by multimerization.
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Affiliation(s)
- Wenyi Li
- School of Chemistry, University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia
| | - Neil M O'Brien-Simpson
- Oral Health CRC, Melbourne Dental School, University of Melbourne, VIC 3010, Australia; Bio21 Institute, University of Melbourne, VIC 3010, Australia
| | - Julien Tailhades
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia
| | - Namfon Pantarat
- Oral Health CRC, Melbourne Dental School, University of Melbourne, VIC 3010, Australia
| | - Raymond M Dawson
- Land Division, Defence Science and Technology Organization, Fishermans Bend, VIC 3207, Australia
| | - Laszlo Otvos
- Department of Biology, Temple University, Philadelphia, PA 19122, USA; Institute of Medical Microbiology, Semmelweis University, Budapest 1089, Hungary
| | - Eric C Reynolds
- Oral Health CRC, Melbourne Dental School, University of Melbourne, VIC 3010, Australia; Bio21 Institute, University of Melbourne, VIC 3010, Australia
| | - Frances Separovic
- School of Chemistry, University of Melbourne, VIC 3010, Australia; Bio21 Institute, University of Melbourne, VIC 3010, Australia
| | - Mohammed Akhter Hossain
- School of Chemistry, University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia.
| | - John D Wade
- School of Chemistry, University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia.
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11
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Boda SK, Basu B. Engineered biomaterial and biophysical stimulation as combinatorial strategies to address prosthetic infection by pathogenic bacteria. J Biomed Mater Res B Appl Biomater 2016; 105:2174-2190. [PMID: 27404048 DOI: 10.1002/jbm.b.33740] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/08/2016] [Accepted: 06/20/2016] [Indexed: 12/25/2022]
Abstract
A plethora of antimicrobial strategies are being developed to address prosthetic infection. The currently available methods for implant infection treatment include the use of antibiotics and revision surgery. Among the bacterial strains, Staphylococcus species pose significant challenges particularly, with regard to hospital acquired infections. In order to combat such life threatening infectious diseases, researchers have developed implantable biomaterials incorporating nanoparticles, antimicrobial reinforcements, surface coatings, slippery/non-adhesive and contact killing surfaces. This review discusses a few of the biomaterial and biophysical antimicrobial strategies, which are in the developmental stage and actively being pursued by several research groups. The clinical efficacy of biophysical stimulation methods such as ultrasound, electric and magnetic field treatments against prosthetic infection depends critically on the stimulation protocol and parameters of the treatment modality. A common thread among the three biophysical stimulation methods is the mechanism of bactericidal action, which is centered on biophysical rupture of bacterial membranes, the generation of reactive oxygen species (ROS) and bacterial membrane depolarization evoked by the interference of essential ion-transport. Although the extent of antimicrobial effect, normally achieved through biophysical stimulation protocol is insufficient to warrant therapeutic application, a combination of antibiotic/ROS inducing agents and biophysical stimulation methods can elicit a clinically relevant reduction in viable bacterial numbers. In this review, we present a detailed account of both the biomaterial and biophysical approaches for achieving maximum bacterial inactivation. Summarizing, the biophysical stimulation methods in a combinatorial manner with material based strategies can be a more potent solution to control bacterial infections. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2174-2190, 2017.
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Affiliation(s)
- Sunil Kumar Boda
- Laboratory for Biomaterials, Materials Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Bikramjit Basu
- Laboratory for Biomaterials, Materials Research Centre, Indian Institute of Science, Bangalore, 560012, India.,Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, 560012, India
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12
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Rao DK, Liu H, Ambudkar SV, Mayer M. A combination of curcumin with either gramicidin or ouabain selectively kills cells that express the multidrug resistance-linked ABCG2 transporter. J Biol Chem 2014; 289:31397-410. [PMID: 25253691 DOI: 10.1074/jbc.m114.576819] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This paper introduces a strategy to kill selectively multidrug-resistant cells that express the ABCG2 transporter (also called breast cancer resistance protein, or BCRP). The approach is based on specific stimulation of ATP hydrolysis by ABCG2 transporters with subtoxic doses of curcumin combined with stimulation of ATP hydrolysis by Na(+),K(+)-ATPase with subtoxic doses of gramicidin A or ouabain. After 72 h of incubation with the drug combinations, the resulting overconsumption of ATP by both pathways inhibits the efflux activity of ABCG2 transporters, leads to depletion of intracellular ATP levels below the viability threshold, and kills resistant cells selectively over cells that lack ABCG2 transporters. This strategy, which was also tested on a clinically relevant human breast adenocarcinoma cell line (MCF-7/FLV1), exploits the overexpression of ABCG2 transporters and induces caspase-dependent apoptotic cell death selectively in resistant cells. This work thus introduces a novel strategy to exploit collateral sensitivity (CS) with a combination of two clinically used compounds that individually do not exert CS. Collectively, this work expands the current knowledge on ABCG2-mediated CS and provides a potential strategy for discovery of CS drugs against drug-resistant cancer cells.
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Affiliation(s)
- Divya K Rao
- From the Departments of Biomedical Engineering and
| | - Haiyan Liu
- From the Departments of Biomedical Engineering and
| | - Suresh V Ambudkar
- the Laboratory of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Michael Mayer
- From the Departments of Biomedical Engineering and Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109 and
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Gurnev PA, Nestorovich EM. Channel-forming bacterial toxins in biosensing and macromolecule delivery. Toxins (Basel) 2014; 6:2483-540. [PMID: 25153255 PMCID: PMC4147595 DOI: 10.3390/toxins6082483] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/08/2014] [Accepted: 08/08/2014] [Indexed: 12/19/2022] Open
Abstract
To intoxicate cells, pore-forming bacterial toxins are evolved to allow for the transmembrane traffic of different substrates, ranging from small inorganic ions to cell-specific polypeptides. Recent developments in single-channel electrical recordings, X-ray crystallography, protein engineering, and computational methods have generated a large body of knowledge about the basic principles of channel-mediated molecular transport. These discoveries provide a robust framework for expansion of the described principles and methods toward use of biological nanopores in the growing field of nanobiotechnology. This article, written for a special volume on "Intracellular Traffic and Transport of Bacterial Protein Toxins", reviews the current state of applications of pore-forming bacterial toxins in small- and macromolecule-sensing, targeted cancer therapy, and drug delivery. We discuss the electrophysiological studies that explore molecular details of channel-facilitated protein and polymer transport across cellular membranes using both natural and foreign substrates. The review focuses on the structurally and functionally different bacterial toxins: gramicidin A of Bacillus brevis, α-hemolysin of Staphylococcus aureus, and binary toxin of Bacillus anthracis, which have found their "second life" in a variety of developing medical and technological applications.
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Affiliation(s)
- Philip A Gurnev
- Physics Department, University of Massachusetts, Amherst, MA 01003, USA.
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Ragioto DAMT, Carrasco LDM, Carmona-Ribeiro AM. Novel gramicidin formulations in cationic lipid as broad-spectrum microbicidal agents. Int J Nanomedicine 2014; 9:3183-92. [PMID: 25061295 PMCID: PMC4085336 DOI: 10.2147/ijn.s65289] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Dioctadecyldimethylammonium bromide (DODAB) is an antimicrobial lipid that can be dispersed as large closed bilayers (LV) or bilayer disks (BF). Gramicidin (Gr) is an antimicrobial peptide assembling as channels in membranes and increasing their permeability towards cations. In mammalian cells, DODAB and Gr have the drawbacks of Gram-positive resistance and high toxicity, respectively. In this study, DODAB bilayers incorporating Gr showed good antimicrobial activity and low toxicity. Techniques employed were spectroscopy, photon correlation spectroscopy for sizing and evaluation of the surface potential at the shear plane, turbidimetric detection of dissipation of osmotic gradients in LV/Gr, determination of bacterial cell lysis, and counting of colony-forming units. There was quantitative incorporation of Gr and development of functional channels in LV. Gr increased the bilayer charge density in LV but did not affect the BF charge density, with localization of Gr at the BF borders. DODAB/Gr formulations substantially reduce Gr toxicity against eukaryotic cells and advantageously broaden the antimicrobial activity spectrum, effectively killing Escherichia coli and Staphylococcus aureus bacteria with occurrence of cell lysis.
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Affiliation(s)
- Danielle A M T Ragioto
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Letícia D M Carrasco
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Ana M Carmona-Ribeiro
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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Horn JN, Kao TC, Grossfield A. Coarse-grained molecular dynamics provides insight into the interactions of lipids and cholesterol with rhodopsin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 796:75-94. [PMID: 24158802 DOI: 10.1007/978-94-007-7423-0_5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Protein function is a complicated interplay between structure and dynamics, which can be heavily influenced by environmental factors and conditions. This is particularly true in the case of membrane proteins, such as the visual receptor rhodopsin. It has been well documented that lipid headgroups, polyunsaturated tails, and the concentration of cholesterol in membranes all play a role in the function of rhodopsin. Recently, we used all-atom simulations to demonstrate that different lipid species have preferential interactions and possible binding sites on rhodopsin's surface, consistent with experiment. However, the limited timescales of the simulations meant that the statistical uncertainty of these results was substantial. Accordingly, we present here 32 independent 1.6 μs coarse-grained simulations exploring lipids and cholesterols surrounding rhodopsin and opsin, in lipid bilayers mimicking those found naturally. Our results agree with those found experimentally and in previous simulations, but with far better statistical certainty. The results demonstrate the value of combining all-atom and coarse-grained models with experiment to provide a well-rounded view of lipid-protein interactions.
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Affiliation(s)
- Joshua N Horn
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, 601 Elmwood Ave, 712, Rochester, NY, 14642, USA
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Ion channel stability of Gramicidin A in lipid bilayers: Effect of hydrophobic mismatch. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:328-38. [DOI: 10.1016/j.bbamem.2013.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 09/20/2013] [Accepted: 10/03/2013] [Indexed: 11/18/2022]
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17
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Shemyakin MM, Ovchinnikov YA, Ivanov VT, Antonov VK, Vinogradova EI, Shkrob AM, Malenkov GG, Evstratov AV, Laine IA, Melnik EI, Ryabova ID. Cyclodepsipeptides as chemical tools for studying ionic transport through membranes. J Membr Biol 2013; 1:402-30. [PMID: 24174058 DOI: 10.1007/bf01869790] [Citation(s) in RCA: 247] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/1969] [Indexed: 11/28/2022]
Abstract
This paper reports a study of the chemistry of valinomycin, enniatins and related membrane-active depsipeptides that increase alkali metal ion permeability of model and biological membranes. The antimicrobial activity of these compounds and their effect on membranes has been correlated with their cation-complexing ability. The complexing reaction has been studied by spectropolarimetric and conductimetric methods. Nuclear magnetic resonance, optical rotatory dispersion, and infrared spectrophotometric studies have revealed the coexistence of conformers of the cyclodepsipeptides in solution and have led to elucidation of the spatial structure of valinomycin, enniatin B and their K(+) complexes. The effect of the conformational properties of the cyclodepsipeptides on their complexation efficiency and selectivity, surface-active properties and behavior towards phospholipid monolayers, bimolecular phospholipid membranes and a number of biological membrane systems has been ascertained. The studies have clearly shown the feasibility of using cyclodepsipeptides with predetermined structural and conformational parameters as chemical tools for membrane studies. it is suggested that the principle of conformation-dependent cation binding through iondipole interactions may possibly lie at the basis of the mode of action of systems governing the natural ion permeability in biological membranes.
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Affiliation(s)
- M M Shemyakin
- Institute for Chemistry of Natural Products, USSR Academy of Sciences, Moscow, USSR
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Wang F, Qin L, Pace CJ, Wong P, Malonis R, Gao J. Solubilized Gramicidin A as Potential Systemic Antibiotics. Chembiochem 2011; 13:51-5. [DOI: 10.1002/cbic.201100671] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Indexed: 11/07/2022]
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19
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Prangkio P, Rao DK, Lance KD, Rubinshtein M, Yang J, Mayer M. Self-assembled, cation-selective ion channels from an oligo(ethylene glycol) derivative of benzothiazole aniline. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2877-85. [PMID: 21889925 DOI: 10.1016/j.bbamem.2011.08.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 07/22/2011] [Accepted: 08/18/2011] [Indexed: 01/01/2023]
Abstract
This paper describes the spontaneous formation of well-defined pores in planar lipid bilayers from the self-assembly of a small synthetic molecule that contains a benzothiazole aniline (BTA) group attached to a tetra-ethylene glycol (EG4) moiety. Macroscopic and single-channel current recordings suggest that these pores are formed by the assembly of four BTA-EG4 monomers with an open pore diameter that appears similar to the one of gramicidin pores (~0.4 nm). The single-channel conductance of these pores is modulated by the pH of the electrolyte and has a minimum at pH~3. Self-assembled pores from BTA-EG4 are selective for monovalent cations and have long open channel lifetimes on the order of seconds. BTA-EG4 monomers in these pores appear to be arranged symmetrically across both leaflets of the bilayer, and spectroscopy studies suggest that the fluorescent BTA group is localized inside the lipid bilayers. In terms of biological activity, BTA-EG4 molecules inhibited growth of gram-positive Bacillus subtilis bacteria (IC50~50 μM) and human neuroblastoma SH-SY5Y cells (IC50~60 μM), while they were not toxic to gram-negative Escherichia coli bacteria at a concentration up to 500 μM. Based on these properties, this drug-like, synthetic, pore-forming molecule with a molecular weight below 500 g mol(-1) might be appealing as a starting material for development of antibiotics or membrane-permeating moieties for drug delivery. From a biophysical point of view, long-lived, well-defined ion-selective pores from BTA-EG4 molecules offer an example of a self-assembled synthetic supramolecule with biological function.
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Affiliation(s)
- Panchika Prangkio
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Avenue, Ann Arbor, Michigan 48109-2110, USA
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Comparative analysis of antimicrobial activities of valinomycin and cereulide, the Bacillus cereus emetic toxin. Appl Environ Microbiol 2011; 77:2755-62. [PMID: 21357430 DOI: 10.1128/aem.02671-10] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cereulide and valinomycin are highly similar cyclic dodecadepsipeptides with potassium ionophoric properties. Cereulide, produced by members of the Bacillus cereus group, is known mostly as emetic toxin, and no ecological function has been assigned. A comparative analysis of the antimicrobial activity of valinomycin produced by Streptomyces spp. and cereulide was performed at a pH range of pH 5.5 to pH 9.5, under anaerobic and aerobic conditions. Both compounds display pH-dependent activity against selected Gram-positive bacteria, including Staphylococcus aureus, Listeria innocua, Listeria monocytogenes, Bacillus subtilis, and Bacillus cereus ATCC 10987. Notably, B. cereus strain ATCC 14579 and the emetic B. cereus strains F4810/72 and A529 showed reduced sensitivity to both compounds, with the latter two strains displaying full resistance to cereulide. Both compounds showed no activity against the selected Gram-negative bacteria. Antimicrobial activity against Gram-positive bacteria was highest at alkaline pH values, where the membrane potential (ΔΨ) is the main component of the proton motive force (PMF). Furthermore, inhibition of growth was observed in both aerobic and anaerobic conditions. Determination of the ΔΨ, using the membrane potential probe DiOC(2)(3) (in the presence of 50 mM KCl) in combination with flow cytometry, demonstrated for the first time the ability of cereulide to dissipate the ΔΨ in sensitive Gram-positive bacteria. The putative role of cereulide production in the ecology of emetic B. cereus is discussed.
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Thyagarajan S, Leiding T, Arsköld SP, Cheprakov AV, Vinogradov SA. Highly non-planar dendritic porphyrin for pH sensing: observation of porphyrin monocation. Inorg Chem 2011; 49:9909-20. [PMID: 20882973 DOI: 10.1021/ic100968p] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metal-free porphyrin-dendrimers provide a convenient platform for the construction of membrane-impermeable ratiometric probes for pH measurements in compartmentalized biological systems. In all previously reported molecules, electrostatic stabilization (shielding) of the core porphyrin by peripheral negative charges (carboxylates) was required to shift the intrinsically low porphyrin protonation pK(a)'s into the physiological pH range (pH 6-8). However, binding of metal cations (e.g., K(+), Na(+), Ca(2+), Mg(2+)) by the carboxylate groups on the dendrimer could affect the protonation behavior of such probes in biological environments. Here we present a dendritic pH nanoprobe based on a highly non-planar tetraaryltetracyclohexenoporphyrin (Ar(4)TCHP), whose intrinsic protonation pK(a)'s are significantly higher than those of regular tetraarylporphyrins, thereby eliminating the need for electrostatic core shielding. The porphyrin was modified with eight Newkome-type dendrons and PEGylated at the periphery, rendering a neutral water-soluble probe (TCHpH), suitable for measurements in the physiological pH range. The protonation of TCHpH could be followed by absorption (e.g., ε(Soret)(dication)∼270,000 M(-1) cm(-1)) or by fluorescence. Unlike most tetraarylporphyrins, TCHpH is protonated in two distinct steps (pK(a)'s 7.8 and 6.0). In the region between the pK(a)'s, an intermediate species with a well-defined spectroscopic signature, presumably a TCHpH monocation, could be observed in the mixture. The performance of TCHpH was evaluated by pH gradient measurements in large unilamellar vesicles. The probe was retained inside the vesicles and did not pass through and/or interact with vesicle membranes, proving useful for quantification of proton transport across phospholipid bilayers. To interpret the protonation behavior of TCHpH we developed a model relating structural changes on the porphyrin macrocycle upon protonation to its basicity. The model was validated by density functional theory (DFT) calculations performed on a planar and non-planar porphyrin, making it possible to rationalize higher protonation pK(a)'s of non-planar porphyrins as well as the easier observation of their monocations.
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Affiliation(s)
- Sujatha Thyagarajan
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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22
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Müller S, Nebe-von-Caron G. Functional single-cell analyses: flow cytometry and cell sorting of microbial populations and communities. FEMS Microbiol Rev 2010; 34:554-87. [DOI: 10.1111/j.1574-6976.2010.00214.x] [Citation(s) in RCA: 266] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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KROLL RG, ANAGNOSTOPOULOS GD. Potassium Leakage as a Lethality Index of Phenol and the Effect of Solute and Water Activity. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1981.tb00878.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Metal complexation is a key mediator or modifier of enzyme structure and function. In addition to divalent and polyvalent metals, group IA metals Na+and K+play important and specific roles that assist function of biological macromolecules. We examine the diversity of monovalent cation (M+)-activated enzymes by first comparing coordination in small molecules followed by a discussion of theoretical and practical aspects. Select examples of enzymes that utilize M+as a cofactor (type I) or allosteric effector (type II) illustrate the structural basis of activation by Na+and K+, along with unexpected connections with ion transporters. Kinetic expressions are derived for the analysis of type I and type II activation. In conclusion, we address evolutionary implications of Na+binding in the trypsin-like proteases of vertebrate blood coagulation. From this analysis, M+complexation has the potential to be an efficient regulator of enzyme catalysis and stability and offers novel strategies for protein engineering to improve enzyme function.
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Affiliation(s)
- Michael J Page
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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26
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Hahn FE. Modes of action of antimicrobial agents. Top Curr Chem (Cham) 2006; 72:1-19. [PMID: 202040 DOI: 10.1007/bfb0048447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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27
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Gibson SE, Lecci C. Aminosäurehaltige Makrocyclen – anwendungsnahe Systeme oder nur Syntheseziele? Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503428] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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28
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Gibson SE, Lecci C. Amino Acid Derived Macrocycles—An Area Driven by Synthesis or Application? Angew Chem Int Ed Engl 2006; 45:1364-77. [PMID: 16444788 DOI: 10.1002/anie.200503428] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The synthesis, structure, and physical properties of macrocycles have fascinated chemists for many years. Their inherent properties make them useful in areas as diverse as ion transport across membranes, development of new antibiotics, and catalysis. In this Review, the authors examine the chemistry of macrocycles containing non-peptidic amino acid derived molecules; the analysis is discussed in terms of function, rather than structure or synthesis. It is revealed that the diverse and imaginative structures created by synthetic chemists are not being fully exploited in application-driven endeavors.
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Affiliation(s)
- Susan E Gibson
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AY, UK.
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29
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Abstract
Gramicidin channels are mini-proteins composed of two tryptophan-rich subunits. The conducting channels are formed by the transbilayer dimerization of nonconducting subunits, which are tied to the bilayer/solution interface through hydrogen bonds between the indole NH groups and the phospholipid backbone and water. The channel structure is known at atomic resolution and the channel's permeability characteristics are particularly well defined: gramicidin channels are selective for monovalent cations, with no measurable permeability to anions or polyvalent cations; ions and water move through a pore whose wall is formed by the peptide backbone; and the single-channel conductance and cation selectivity vary when the amino acid sequence is varied, even though the permeating ions make no contact with the amino acid side chains. Given the amount of experimental information that is available--for both the wild-type channels and for channels formed by amino acid-substituted gramicidin analogues--gramicidin channels provide important insights into the microphysics of ion permeation through bilayer-spanning channels. For the same reason, gramicidin channels constitute the system of choice for evaluating computational strategies for obtaining mechanistic insights into ion permeation through the complex channels formed by integral membrane proteins.
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Affiliation(s)
- Olaf S Andersen
- Weill Medical College of Cornell University, New York, NY 10021, USA.
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30
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Leevy WM, Weber ME, Gokel MR, Hughes-Strange GB, Daranciang DD, Ferdani R, Gokel GW. Correlation of bilayer membrane cation transport and biological activity in alkyl-substituted lariat ethers. Org Biomol Chem 2005; 3:1647-52. [PMID: 15858645 PMCID: PMC2615582 DOI: 10.1039/b418194h] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dialkyldiaza-18-crown-6 lariat ethers having twin n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, 1-oxodecyl and 1-oxododecyl side arms were prepared and studied. Cation transport in liposomes mediated by these compounds showed discontinuous activity that correlated with toxicity to the bacteria E. coli and B. Subtilis, and the yeast S. Cerevisiae. Transport, toxicity and membrane depolarization studies all suggest that side chain length affords very different interactions in a bilayer membrane compared with bulk phases. An explanation for activity in terms of carrier transport and restricted transverse relaxation is proposed.
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Affiliation(s)
- W Matthew Leevy
- Departments of Chemistry and Molecular Biology & Pharmacology, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8103, St. Louis, MO 63110, USA
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31
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Finikova O, Galkin A, Rozhkov V, Cordero M, Hägerhäll C, Vinogradov S. Porphyrin and tetrabenzoporphyrin dendrimers: tunable membrane-impermeable fluorescent pH nanosensors. J Am Chem Soc 2003; 125:4882-93. [PMID: 12696908 DOI: 10.1021/ja0341687] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The pH dependencies of the UV-vis and fluorescent spectra of new water-soluble dendritic porphyrins and tetrabenzoporphyrins were studied. Because of extended pi-conjugation and nonplanar distortion, the absorption and the emission bands of tetraaryltetrabenzoporphyrins (Ar(4)TBP) are red-shifted and do not overlap with those of regular tetraarylporphyrins (Ar(4)P). When encapsulated inside dendrimers with hydrophilic outer layers, Ar(4)Ps and Ar(4)TBPs become water soluble and can serve as pH indicators, with pK's adjustable by the peripheral charges on the dendrimers. Two new dendritic porphyrins, Gen 4 polyglutamic porphyrin dendrimer H(2)P-Glu(4)OH (1) with 64 peripheral carboxylates and Gen 1 poly(ester amide) Newkome-type tetrabenzoporphyrin dendrimer H(2)TBP-Nw(1)OH (2) with 36 peripheral carboxylates, were synthesized and characterized. The pK's of the encapsulated porphyrins (pK(H)()2(P)(-)(Glu)()4(OH) = 6.2 and pK(H)()2(TBP)(-)(Nw)()1(OH) = 6.3) were found to be strongly influenced by the dendrimers, revealing significant electrostatic shielding of the cores by the peripheral charges. The titration curves obtained by differential excitation using the mixtures of the dendrimers were shown to be identical to those determined for the dendrimers individually. Due to their peripheral carboxylates and nanometric molecular size, porphyrin dendrimers cannot penetrate through phospholipid membranes. Dendrimer 1 was captured inside phospholipid liposomes, which were suspended in a solution containing dendrimer 2. No response from 1 was detected upon pH changes in the bulk solution, while the response from 2 was predictably strong. When proton channels were created in the liposome walls, both compounds responded equally to the bulk pH changes. These results suggest that porphyrin dendrimers can be used as fluorescent pH indicators for proton gradient measurements.
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Affiliation(s)
- Olga Finikova
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Grage SL, Wang J, Cross TA, Ulrich AS. Solid-state 19F-NMR analysis of 19F-labeled tryptophan in gramicidin A in oriented membranes. Biophys J 2002; 83:3336-50. [PMID: 12496101 PMCID: PMC1302409 DOI: 10.1016/s0006-3495(02)75334-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The response of membrane-associated peptides toward the lipid environment or other binding partners can be monitored by solid-state NMR of suitably labeled side chains. Tryptophan is a prominent amino acid in transmembrane helices, and its (19)F-labeled analogues are generally biocompatible and cause little structural perturbation. Hence, we use 5F-Trp as a highly sensitive NMR probe to monitor the conformation and dynamics of the indole ring. To establish this (19)F-NMR strategy, gramicidin A was labeled with 5F-Trp in position 13 or 15, whose chi(1)/chi(2) torsion angles are known from previous (2)H-NMR studies. First, the alignment of the (19)F chemical shift anisotropy tensor within the membrane was deduced by lineshape analysis of oriented samples. Next, the three principal axes of the (19)F chemical shift anisotropy tensor were assigned within the molecular frame of the indole ring. Finally, determination of chi(1)/chi(2) for 5F-Trp in the lipid gel phase showed that the side chain alignment differs by up to 20 degrees from its known conformation in the liquid crystalline state. The sensitivity gain of (19)F-NMR and the reduction in the amount of material was at least 10-fold compared with previous (2)H-NMR studies on the same system and 100-fold compared with (15)N-NMR.
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Hughes MP, Morgan H, Rixon FJ. Measuring the dielectric properties of herpes simplex virus type 1 virions with dielectrophoresis. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1571:1-8. [PMID: 12031284 DOI: 10.1016/s0304-4165(02)00161-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
An investigation has been performed into the biophysical properties of the enveloped mammalian virus, herpes simplex virus type 1 (HSV-1). The dielectrophoretic behaviour of the virus particles was measured as a function of applied frequency (over the range 100 kHz-20 MHz) and conductivity of the suspending medium (over the range 1-100 mS m(-1)). The dielectric properties of the virus were determined from the dielectrophoretic data using the smeared-out shell model. The data suggest that the intact particle has a surface conductance of 0.3 nS, an internal and membrane permittivity of 75varepsilon(o) and 7.5varepsilon(o), respectively, an internal conductivity of approximately 0.1 S m(-1) and a zeta potential of 70 mV. The dielectric properties were measured for intact, fresh virus particles and also for particles following exposure to various modifying agents, such as treatment with enzymes, ionophores and ageing. It is shown that the observed changes in the dielectrophoretic spectrum, and the variations in the dielectric properties of the virus concur with the expected physiological effects of these agents.
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Affiliation(s)
- Michael P Hughes
- Department of Electronics and Electrical Engineering, Bioelectronic Research Centre, University of Glasgow, Scotland, Glasgow, UK
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34
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Metzler DE, Metzler CM, Sauke DJ. Lipids, Membranes, and Cell Coats. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50011-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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35
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Chapter 9 A Short History of Ion Channels and Signal Propagation. CURRENT TOPICS IN MEMBRANES 1999. [DOI: 10.1016/s0070-2161(08)61047-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Ketchem R, Roux B, Cross T. High-resolution polypeptide structure in a lamellar phase lipid environment from solid state NMR derived orientational constraints. Structure 1997; 5:1655-69. [PMID: 9438865 DOI: 10.1016/s0969-2126(97)00312-2] [Citation(s) in RCA: 233] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Solid-state nuclear magnetic resonance (NMR) spectroscopy provides novel structural constraints from uniformly aligned samples. These orientational constraints orient specific atomic sites with respect to the magnetic field direction and the unique molecular axis of alignment. Solid-state NMR is uniquely and ideally suited for providing such structural constraints on polypeptides and proteins in a lamellar phase lipid environment. Membrane protein structure represents a great challenge for structural biologists; a new approach for characterizing high resolution three-dimensional structure in such an environment is needed. RESULTS The optimal use of orientational constraints for defining three-dimensional structures is demonstrated with the elucidation of the gramicidin A channel structure at high resolution. Initial structures are refined against both the experimental constraints and the CHARMM energy using a novel simulated-annealing protocol to define torsion angle solutions with an error bar of approximately +/- 5 degrees. CONCLUSIONS This analysis results in the determination of a high-resolution, time averaged structure of gramicidin A obtained in a lipid bilayer environment above the gel-to-liquid crystalline phase transition temperature. It is demonstrated that solid-state NMR can be used to establish polypeptide, and potentially protein, structures in such an environment. Furthermore, this high-resolution structure is demonstrated to provide new insights into polypeptide function. For the gramicidin A channel the roles of the indole groups that facilitate ion transport and details of the cation solvation environment provided by the amide oxygens are characterized.
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Affiliation(s)
- R Ketchem
- Center for Interdisciplinary Magnetic Resonance at the National High Magnetic Field Laboratory, Florida State University, Tallahassee 32306-4005, USA
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Abstract
Gramicidin is a polypeptide antibiotic that forms monovalent cation-specific channels in membrane environments. In organic solvents and in lipids containing unsaturated fatty acid chains, it forms a double-helical "pore" structure, in which two monomers are intertwined. This form of gramicidin can bind two cations inside its lumen, and the crystal structures of both an ion complex and an ion-free form have been determined. In this study, we have used circular dichroism (CD) spectroscopy to examine the binding mechanism and the binding constants (K1 and K2) of cations to gramicidin in the double helical form in methanol solution. The dramatic change in optical rotation in the far-ultraviolet CD spectrum of gramicidin provides a useful tool for monitoring the binding. The binding mechanism appears to involve a large conformation change associated with the binding of ions to the first of the two sites. The calculated values for the K1 binding constants for alkaline cations are considerably smaller than the K2 binding constants. The order of binding affinity for alkaline cations is similar to that for the helical dimer "channel" form of gramicidin, i.e., Cs+ approximately Rb+ > > K+ > Li+, but in comparison to the helical dimer form, the binding to double-helical dimers is dominated by a cation size-dependent conformational change in the gramicidin structure.
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Affiliation(s)
- Y Chen
- Department of Crystallography, Birkbeck College, University of London, England
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Abstract
Nisin is a ribosomally synthesized peptide that has broad-spectrum antibacterial activity, including activity against many bacteria that are food-spoilage pathogens. Nisin is produced as a fermentation product of a food-grade bacterium, and the safety and efficacy of nisin as a food preservative have resulted in its widespread use throughout the world, including the U.S. Nisin is a member of the class of antimicrobial substances known as lantibiotics, so called because they contain the unusual amino acid lanthionine. Lantibiotics, in general, have considerable promise as food preservatives, although only nisin has been sufficiently well characterized to be used for this purpose. As the number of known natural lantibiotics has increased and their useful characteristics have been explored, it has become desirable to synthesize structural analogs of nisin and other lantibiotics that do not occur naturally. The fact that lantibiotics are gene-encoded peptides synthesized by transcription and translation allows structural variants to be generated by mutagenesis. This review focuses on the progress that has been made in the construction and biological expression of genetically engineered nisin structural analogs. For example, a host-vector pair has been engineered that permits the construction of mutants of the structural gene for subtilin, which is a naturally occurring structural analog of nisin. The vector is designed in such a way that the mutant gene can be substituted for the natural subtilin gene in the chromosome of Bacillus subtilis, which in turn directs the transcription, translation, posttranslational modifications, and secretion of the mature form of the structural analog. Several structural analogs have been constructed, and their properties have provided insight into some of the structure-function relationships in lantibiotics, as well as their mechanism of antimicrobial action. These advances are assessed together with potential problems in the future development of nisin analogs as valuable new food preservatives.
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Affiliation(s)
- J N Hansen
- Department of Chemistry and Biochemistry, College of Life Sciences, University of Maryland, College Park 20742-2021
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Abstract
The ion channel forming peptide gramicidin A adopts a number of distinct conformations in different environments. We have developed a new method to analyze and display the pore dimensions of ion channels. The procedure is applied to two x-ray crystal structures of gramicidin that adopt distinct antiparallel double helical dimer conformations and a nuclear magnetic resonance (NMR) structure for the beta6.3 NH2-terminal to NH2-terminal dimer. The results are discussed with reference to ion conductance properties and dependence of pore dimensions on the environment.
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Affiliation(s)
- O S Smart
- Department of Crystallography, Birkbeck College, University of London, England
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Liu W, Hansen JN. The antimicrobial effect of a structural variant of subtilin against outgrowing Bacillus cereus T spores and vegetative cells occurs by different mechanisms. Appl Environ Microbiol 1993; 59:648-51. [PMID: 8434932 PMCID: PMC202163 DOI: 10.1128/aem.59.2.648-651.1993] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Subtilin is a ribosomally synthesized antimicrobial peptide that contains several unusual amino acids as a result of posttranslational modifications. Site-directed mutagenesis was employed to construct a structural variant of subtilin in which the unusual dehydroalanine (Dha) residue at position 5 was changed to alanine. Proton nuclear magnetic resonance spectroscopy, amino acid composition, and N-terminal sequence analysis established that the mutation did not disrupt posttranslational processing of the precursor peptide. This mutant subtilin was devoid of antimicrobial activity as assessed by its lack of inhibitory effects on outgrowth of Bacillus cereus T spores. However, this same mutant subtilin was fully active with respect to its ability to induce lysis of vegetative B. cereus T cells. Because an intact Dha-5 residue is required in the one instance but not in the other, it was concluded that the molecular mechanism by which subtilin inhibits (without lysis) spore outgrowth is not the same as the mechanism by which it inhibits (with lysis) vegetative cells.
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Affiliation(s)
- W Liu
- Department of Chemistry and Biochemistry, University of Maryland, College Park 20742
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Vadeboncoeur C, Brochu D, Reizer J. Quantitative determination of the intracellular concentration of the various forms of HPr, a phosphocarrier protein of the phosphoenolpyruvate: sugar phosphotransferase system in growing cells of oral streptococci. Anal Biochem 1991; 196:24-30. [PMID: 1716075 DOI: 10.1016/0003-2697(91)90112-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A simple procedure for quantitative estimation of the different phosphorylated forms of the phosphocarrier protein HPr in growing cells of oral streptococci is described. The growth of the cells was rapidly stopped by acidification of the medium and concomitant addition of the ionophore Gramicidin D. This procedure inactivated Enzyme I, HPr(Ser) kinase, HPr(Ser-P) phosphatase, and the enzymes involved in the metabolism of the allosteric effectors as well as the substrates of HPr phosphorylation. The cellular concentrations of HPr (His approximately P), HPr (Ser-P), HPr (His approximately P) (Ser-P), and free HPr were then determined by crossed immunoelectrophoresis.
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Affiliation(s)
- C Vadeboncoeur
- Groupe de recherche en écologie buccale (GREB), Department of Biochemistry (Sciences) School of Dental Medicine, Université Laval, Ste-Foy, Quebec
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Langs DA, Smith GD, Courseille C, Précigoux G, Hospital M. Monoclinic uncomplexed double-stranded, antiparallel, left-handed beta 5.6-helix (increases decreases beta 5.6) structure of gramicidin A: alternate patterns of helical association and deformation. Proc Natl Acad Sci U S A 1991; 88:5345-9. [PMID: 1711230 PMCID: PMC51869 DOI: 10.1073/pnas.88.12.5345] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A comparison of the monoclinic and orthorhombic crystal structures of the uncomplexed double-stranded, antiparallel, left-handed beta-helix (5.6 amino acid residues per turn) (increases decreases beta 5.6) conformers of gramicidin A reveals marked differences in the tryptophan side-chain orientations and the degree of helical uniformity of the dimer and in the manner in which these helical dimers associate with one another in the crystal. The helix of the orthorhombic dimer exhibits a regular pattern of bulges and constrictions that appears to be induced by crystal packing forces affecting tryptophan side chains that are aligned parallel to the helix axis. The monoclinic dimer is more uniform than the orthorhombic dimer as a consequence of pi stacking interactions between dimers in which orientation of tryptophan side chains is normal to the helix axis to relieve the lateral crystal packing forces that may locally twist and deform the helix. It may be inferred from these observations that lipid interactions may be expected to destabilize the increases decreases beta 5.6 helix when it is inserted into a membrane bilayer.
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Affiliation(s)
- D A Langs
- Department of Molecular Biophysics, Medical Foundation of Buffalo, Inc., NY 14203
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Moll GN, van den Eertwegh V, Tournois H, Roelofsen B, Op den Kamp JA, van Deenen LL. Growth inhibition of Plasmodium falciparum in in vitro cultures by selective action of tryptophan-N-formylated gramicidin incorporated in lipid vesicles. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1062:206-10. [PMID: 1706202 DOI: 10.1016/0005-2736(91)90394-n] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We studied the differential effect of tryptophan-N-formylated gramicidin on uninfected and Plasmodium falciparum-infected erythrocytes. Trp-N-formylated gramicidin induces a much faster leakage of K+ from infected cells than from uninfected cell whereas, and at an even lower concentration, gramicidin A' causes a rapid K+ leakage from both uninfected and infected cells. We also studied the effect of Trp-N-formylated gramicidin and gramicidin A' incorporated in liposomes on the growth of Plasmodium falciparum in an in vitro culture. Incorporation of Trp-N-formylated gramicidin in the membranes of so-called 'stealth' vesicles strongly decreases the concentration needed to induce 50% inhibition of parasite growth. Moreover, no decrease in the K+ content of uninfected cells was observed when cells were exposed to liposome-incorporated Trp-N-formylated gramicidin at a concentration which causes full inhibition of parasite growth. These observations strongly suggest that Trp-N-formylated gramicidin incorporated in 'stealth' vesicles ends up specifically in the infected cell, thereby inhibiting the growth of the growth of the malaria parasite.
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Affiliation(s)
- G N Moll
- Centre for Biomembranes and Lipid Enzymology, University of Utrecht, The Netherlands
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Bystrov V, Arseniev A. Diversity of the gramicidin a spatial structure: two-dimensional 1H nmr study in solution. Tetrahedron 1988. [DOI: 10.1016/s0040-4020(01)86126-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
In contrast to results reported with other bacteria, uptake of 32Pi in Streptococcus pyogenes was found to occur rapidly in starved cultures and to be strongly and immediately inhibited by addition of exogenous glycolytic energy sources (such as glucose) and nonglycolytic sources of ATP (such as arginine). Preincubation of starved cells with NaF, iodoacetate, or arsenate eliminated the inhibiting effect of glucose but not that of arginine. In accordance with the hypothesis that transport was attributable to Pi-Pi exchange, uptake and efflux of 32Pi in the presence of trans unlabeled Pi exhibited similar characteristics and were largely eliminated by reduction of the trans Pi concentration. Neither process was inhibited appreciably by pretreatment of cells with ionophores or metabolic inhibitors, but both processes were abolished by exposure to p-chloromercuribenzoate. Inhibition by both exogenous energy sources resulted in a reduction in the maximal velocity of transport (Vmax). Whereas arginine also caused a shift in the apparent Michaelis-Menten constant (Km) to larger values, glucose did not alter the Km. On the basis of the results reported, we propose that the rate of Pi exchange is determined positively by the intracellular and extracellular concentrations of Pi and negatively by ATP or metabolites thereof. The mechanism of ATP action is unknown but could involve either covalent or noncovalent modification of the carrier protein.
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Temperature-jump and voltage-jump experiments at planar lipid membranes support an aggregational (micellar) model of the gramicidin A ion channel. J Membr Biol 1986; 89:23-37. [PMID: 2420993 DOI: 10.1007/bf01870893] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The kinetics of formation and dissociation of channels formed by gramicidin A and two analogues in planar lipid membranes was studied using a laser temperature-jump technique developed earlier [Brock, W., Stark, G., Jordan, P.C. (1981), Biophys. Chem. 13:329-348]. The time course of the electric current was found to agree with a single exponential term plus a linear drift. In case of gramicidin A the relaxation time was identical to that reported for V-jump experiments [Bamberg, E., Läuger, P. (1973), J. Membrane Biol. 11:177-194], which were interpreted on the basis of a dimerization reaction. The same results were obtained for gramicidin A and for chemically dimerized malonyl-bis-desformylgramicidin. It is therefore suggested that the dimerization represents a parallel association of two dimers to a tetramer. There is evidence that the tetramer, contrary to the presently favored dimer hypothesis, is the smallest conductance unit of an active gramicidin channel. An additional V-jump-induced relaxation process of considerably larger time constant is interpreted as a further aggregation of gramicidin dimers.
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Vadeboncoeur C, Proulx M, Trahan L. Effect of gramicidin D on the acidogenic properties of oral streptococci and human dental plaque. J Dent Res 1982; 61:632-5. [PMID: 6177722 DOI: 10.1177/00220345820610050201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The effect of gramicidin D, Gramicidin S, and carbonylcyanide p-trifluoromethoxyphenyl hydrazone on the glycolysis of various oral streptococci was investigated. Gramicidin D was the most effective and inhibited the glycolysis of all the streptococci studied in the presence of the most common sugars found in man's diet (sucrose, lactose, glucose, and fructose). A concentration of 2.5 X 10(-6) M gramicidin D was sufficient to decrease significantly the rate of glycolysis of human dental plaque in the presence of sucrose. The use of this ionophore as a caries preventive agent is discussed.
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Fisher R, Blumenthal T. An interaction between gramicidin and the sigma subunit of RNA polymerase. Proc Natl Acad Sci U S A 1982; 79:1045-8. [PMID: 6175958 PMCID: PMC345896 DOI: 10.1073/pnas.79.4.1045] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Gramicidin, a peptide antibiotic produced by Bacillus brevis, inhibits initiation of transcription by RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6). We show here that the presence of gramicidin causes an increase in the rate of cleavage of the sigma subunit of Escherichia coli RNA polymerase by trypsin, although it does not alter the cleavage rate of any of the core subunits. Furthermore, whereas isolated sigma is cleaved much faster than is sigma in holoenzyme, gramicidin substantially decreases the trypsin cleavage rate of isolated sigma. Inhibition of RNA polymerase activity by gramicidin in consistent with a sigma-specific effect: the antibiotic is a strong inhibitor of transcription of T7 phage DNA, which requires sigma for activity, but it has little effect on transcription of sigma-independent templates, such as poly(dA-dT).poly)dA-dT) and calf thymus DNA. These results are discussed in light of the hypothesized role for gramicidin in the initiation of sporulation of B. brevis.
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Inhibition of stomatal opening by cyclic ‘crown’ polyethers in commelina communis, and a correlation with lipophilicity and bonding. Inorganica Chim Acta 1982. [DOI: 10.1016/s0020-1693(00)85781-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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356 — The stoichiometry of the energy-dependent ionic exchange in streptococcus faecalis. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/0302-4598(81)85002-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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