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Caselli L, Köhler S, Schirone D, Humphreys B, Malmsten M. Conformational control of antimicrobial peptide amphiphilicity: consequences for boosting membrane interactions and antimicrobial effects of photocatalytic TiO 2 nanoparticles. Phys Chem Chem Phys 2024; 26:16529-16539. [PMID: 38828872 DOI: 10.1039/d4cp01724b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
This study reports on the effects of conformationally controlled amphiphilicity of antimicrobial peptides (AMPs) on their ability to coat TiO2 nanoparticles (NPs) and boost the photocatalytic antimicrobial effects of such NPs. For this, TiO2 NPs were combined with AMP EFK17 (EFKRIVQRIKDFLRNLV), displaying a disordered conformation in aqueous solution but helix formation on interaction with bacterial membranes. The membrane-bound helix is amphiphilic, with all polar and charged amino acid residues located at one side and all non-polar and hydrophobic residues on the other. In contrast, the d-enantiomer variant EFK17-d (E(dF)KR(dI)VQR(dI)KD(dF)LRNLV) is unable to form the amphiphilic helix on bacterial membrane interaction, whereas the W-residues in EFK17-W (EWKRWVQRWKDFLRNLV) boost hydrophobic interactions of the amphiphilic helix. Circular dichroism results showed the effects displayed for the free peptide, to also be present for peptide-coated TiO2 NPs, causing peptide binding to decrease in the order EFK17-W > EFK17 > EFK17-d. Notably, the formation of reactive oxygen species (ROS) by the TiO2 NPs was essentially unaffected by the presence of peptide coating, for all the peptides investigated, and the coatings stabilized over hours of UV exposure. Photocatalytic membrane degradation from TiO2 NPs coated with EFK17-W and EFK17 was promoted for bacteria-like model bilayers containing anionic phosphatidylglycerol but suppressed in mammalian-like bilayers formed by zwitterionic phosphatidylcholine and cholesterol. Structural aspects of these effects were further investigated by neutron reflectometry with clear variations observed between the bacteria- and mammalian-like model bilayers for the three peptides. Mirroring these results in bacteria-like model membranes, combining TiO2 NPs with EFK17-W and EFK17, but not with non-adsorbing EFK17-d, resulted in boosted antimicrobial effects of the resulting cationic composite NPs already in darkness, effects enhanced further on UV illumination.
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Affiliation(s)
- Lucrezia Caselli
- Department of Physical Chemistry 1, Lund University, SE-22100 Lund, Sweden.
| | - Sebastian Köhler
- LINXS Institute of Advanced Neutron and X-ray Science, Scheelevagen 19, 22370 Lund, Sweden
| | - Davide Schirone
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Malmö University, 20506 Malmö, Sweden
| | - Ben Humphreys
- Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France
| | - Martin Malmsten
- Department of Physical Chemistry 1, Lund University, SE-22100 Lund, Sweden.
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark
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2
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Sharma P, Vaiwala R, Gopinath AK, Chockalingam R, Ayappa KG. Structure of the Bacterial Cell Envelope and Interactions with Antimicrobials: Insights from Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:7791-7811. [PMID: 38451026 DOI: 10.1021/acs.langmuir.3c03474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Bacteria have evolved over 3 billion years, shaping our intrinsic and symbiotic coexistence with these single-celled organisms. With rising populations of drug-resistant strains, the search for novel antimicrobials is an ongoing area of research. Advances in high-performance computing platforms have led to a variety of molecular dynamics simulation strategies to study the interactions of antimicrobial molecules with different compartments of the bacterial cell envelope of both Gram-positive and Gram-negative species. In this review, we begin with a detailed description of the structural aspects of the bacterial cell envelope. Simulations concerned with the transport and associated free energy of small molecules and ions through the outer membrane, peptidoglycan, inner membrane and outer membrane porins are discussed. Since surfactants are widely used as antimicrobials, a section is devoted to the interactions of surfactants with the cell wall and inner membranes. The review ends with a discussion on antimicrobial peptides and the insights gained from the molecular simulations on the free energy of translocation. Challenges involved in developing accurate molecular models and coarse-grained strategies that provide a trade-off between atomic details with a gain in sampling time are highlighted. The need for efficient sampling strategies to obtain accurate free energies of translocation is also discussed. Molecular dynamics simulations have evolved as a powerful tool that can potentially be used to design and develop novel antimicrobials and strategies to effectively treat bacterial infections.
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Affiliation(s)
- Pradyumn Sharma
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Rakesh Vaiwala
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Amar Krishna Gopinath
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Rajalakshmi Chockalingam
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
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3
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Caselli L, Nylander T, Malmsten M. Neutron reflectometry as a powerful tool to elucidate membrane interactions of drug delivery systems. Adv Colloid Interface Sci 2024; 325:103120. [PMID: 38428362 DOI: 10.1016/j.cis.2024.103120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/03/2024]
Abstract
The last couple of decades have seen an explosion of novel colloidal drug delivery systems, which have been demonstrated to increase drug efficacy, reduce side-effects, and provide various other advantages for both small-molecule and biomacromolecular drugs. The interactions of delivery systems with biomembranes are increasingly recognized to play a key role for efficient eradication of pathogens and cancer cells, as well as for intracellular delivery of protein and nucleic acid drugs. In parallel, there has been a broadening of methodologies for investigating such systems. For example, advanced microscopy, mass-spectroscopic "omic"-techniques, as well as small-angle X-ray and neutron scattering techniques, which only a few years ago were largely restricted to rather specialized areas within basic research, are currently seeing increased interest from researchers within wide application fields. In the present discussion, focus is placed on the use of neutron reflectometry to investigate membrane interactions of colloidal drug delivery systems. Although the technique is still less extensively employed for investigations of drug delivery systems than, e.g., X-ray scattering, such studies may provide key mechanistic information regarding membrane binding, re-modelling, translocation, and permeation, of key importance for efficacy and toxicity of antimicrobial, cancer, and other therapeutics. In the following, examples of this are discussed and gaps/opportunities in the research field identified.
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Affiliation(s)
| | - Tommy Nylander
- Physical Chemistry 1, Lund University, S-221 00 Lund, Sweden
| | - Martin Malmsten
- Physical Chemistry 1, Lund University, S-221 00 Lund, Sweden; Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark.
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4
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Caselli L, Parra-Ortiz E, Micciulla S, Skoda MWA, Häffner SM, Nielsen EM, van der Plas MJA, Malmsten M. Boosting Membrane Interactions and Antimicrobial Effects of Photocatalytic Titanium Dioxide Nanoparticles by Peptide Coating. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2309496. [PMID: 38402437 DOI: 10.1002/smll.202309496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/30/2024] [Indexed: 02/26/2024]
Abstract
Photocatalytic nanoparticles offer antimicrobial effects under illumination due to the formation of reactive oxygen species (ROS), capable of degrading bacterial membranes. ROS may, however, also degrade human cell membranes and trigger toxicity. Since antimicrobial peptides (AMPs) may display excellent selectivity between human cells and bacteria, these may offer opportunities to effectively "target" nanoparticles to bacterial membranes for increased selectivity. Investigating this, photocatalytic TiO2 nanoparticles (NPs) are coated with the AMP LL-37, and ROS generation is found by C11 -BODIPY to be essentially unaffected after AMP coating. Furthermore, peptide-coated TiO2 NPs retain their positive ζ-potential also after 1-2 h of UV illumination, showing peptide degradation to be sufficiently limited to allow peptide-mediated targeting. In line with this, quartz crystal microbalance measurements show peptide coating to promote membrane binding of TiO2 NPs, particularly so for bacteria-like anionic and cholesterol-void membranes. As a result, membrane degradation during illumination is strongly promoted for such membranes, but not so for mammalian-like membranes. The mechanisms of these effects are elucidated by neutron reflectometry. Analogously, LL-37 coating promoted membrane rupture by TiO2 NPs for Gram-negative and Gram-positive bacteria, but not for human monocytes. These findings demonstrate that AMP coating may selectively boost the antimicrobial effects of photocatalytic NPs.
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Affiliation(s)
- Lucrezia Caselli
- Department of Pharmacy, University of Copenhagen, Copenhagen, DK-2100, Denmark
- Department of Physical Chemistry 1, Lund University, Lund, SE-22100, Sweden
| | - Elisa Parra-Ortiz
- Department of Pharmacy, University of Copenhagen, Copenhagen, DK-2100, Denmark
- Novonesis, Biologiens Vej 2, Lyngby, DK-2800 Kgs, Denmark
| | - Samantha Micciulla
- Institut Laue-Langevin, CS 20156, Grenoble Cedex 9, 38042, France
- Laboratoire Interdisciplinaire de Physique (LIPhy), Saint Martin d'Hères, 38402, France
- Centre National de la Recherche Scientifique (CNRS), Saint-Martin-d'Hères, Auvergne-Rhône-Alpes, France
| | - Maximilian W A Skoda
- ISIS Pulsed Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell, OX11 0QX, UK
| | - Sara Malekkhaiat Häffner
- Department of Pharmacy, University of Copenhagen, Copenhagen, DK-2100, Denmark
- RISE Research Institutes of Sweden, Malvinas väg 3, Stockholm, 114 86, Sweden
| | | | | | - Martin Malmsten
- Department of Pharmacy, University of Copenhagen, Copenhagen, DK-2100, Denmark
- Department of Physical Chemistry 1, Lund University, Lund, SE-22100, Sweden
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Kyselová L, Řezanka T. Stereochemistry of aminoacylated cardiolipins and phosphatidylglycerols from bacteria. Electrophoresis 2023. [PMID: 37860988 DOI: 10.1002/elps.202300165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 09/26/2023] [Accepted: 10/08/2023] [Indexed: 10/21/2023]
Abstract
Hydrophilic interaction liquid chromatography (HILIC) connected with electrospray high-resolution tandem mass spectrometry (MS) was used for the analysis of unusual amino acid (AA) substituted phosphatidylglycerols (PG) and cardiolipins (CL) in mesophilic and thermophilic bacteria. Individual peaks from the lipid class separation by HILIC were isolated and hydrolyzed to determine the absolute configuration of the aminoacyl side chain. The configuration of the aminoacyl side chain was assigned by indirect liquid chromatography (LC) enantiomer separation after the hydrolysis of the aminoacylated (aminoacyl) lipids using N-(4-nitrophenoxycarbonyl)-l-phenylalanine 2-methoxyethyl ester as chiral derivatizing agent and reversed phase LC-MS for analysis. When two chromatographic methods were combined, less common AAs, such as d-allo-Ile and d-allo-Thr, were identified. The taxonomic classification of bacteria showed that bacteria of the family Bacillaceae (Bacillus and Geobacillus) produce branched-chain AAs, that is, d-allo-Ile, d-Ile, and d-Leu. These AAs were present only in the genera Bacillus and Geobacillus and not in Alicyclobacillus acidoterrestris (family Alicyclobacillaceae). On the contrary, hydroxy AAs, that is, l- and d-Thr, and l- and d-allo-Thr, were identified as aminoacyl-PG and aminoacyl-CL in A. acidoterrestris and were not present in the genera Bacillus and Geobacillus. Therefore, the complete analysis made it possible to identify the stereochemistry of AAs in aminoacyl PGs and CLs and use this fact for chemotaxonomy.
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Affiliation(s)
- Lucie Kyselová
- Research Institute of Brewing and Malting, Prague, Czech Republic
| | - Tomáš Řezanka
- Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
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Kozon-Markiewicz D, Kopiasz RJ, Głusiec M, Łukasiak A, Bednarczyk P, Jańczewski D. Membrane lytic activity of antibacterial ionenes, critical role of phosphatidylcholine (PC) and cardiolipin (CL). Colloids Surf B Biointerfaces 2023; 229:113480. [PMID: 37536168 DOI: 10.1016/j.colsurfb.2023.113480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/16/2023] [Accepted: 07/26/2023] [Indexed: 08/05/2023]
Abstract
Understanding the mechanism by which an antibacterial agent interacts with a model membrane provides vital information for better design of future antibiotics. In this study, we investigated two antibacterial polymers, hydrophilic C0-T-p and hydrophobic C8-T-p ionenes, known for their potent antimicrobial activity and ability to disrupt the integrity of lipid bilayers. Our hypothesize is that the composition of a lipid bilayer alters the mechanism of ionenes action, potentially providing an explanation for the observed differences in their bioactivity and selectivity. Calcein release experiments utilizing a range of liposomes to examine the impact of (i) cardiolipin (CL) to phosphatidylglycerol (PG) ratio, (ii) overall vesicle charge, and (iii) phosphatidylethanolamine (PE) to phosphatidylcholine (PC) ratio on the activity of ionenes were performed. Additionally, polymer-bilayer interactions were also investigated through vesicle fusion assay and the black lipid membrane (BLM) technique The activity of C0-T-p is strongly influenced by the amount of cardiolipin, while the activity of C8-T-p primarily depends on the overall vesicle charge. Consequently, C0-T-p acts through interactions with CL, whereas C8-T-p modifies the bulk properties of the membrane in a less-specific manner. Moreover, the presence of a small amount of PC in the membrane makes the vesicle resistant to permeabilization by tested molecules. Intriguingly, more hydrophilic C0-T-p retains higher membrane activity compared to the hydrophobic C8-T-p. However, both ionenes induce vesicle fusion and increase lipid bilayer ion permeability.
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Affiliation(s)
| | - Rafał J Kopiasz
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Martyna Głusiec
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Agnieszka Łukasiak
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Dominik Jańczewski
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
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Kumari M, Kashyap HK. Wrapping-Trapping versus Extraction Mechanism of Bactericidal Activity of MoS 2 Nanosheets against Staphylococcus aureus Bacterial Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:5440-5453. [PMID: 37013340 DOI: 10.1021/acs.langmuir.3c00118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The promising broad-spectrum antibacterial activity of two-dimensional molybdenum disulfide (2D MoS2) has been widely recognized in the past decade. However, a comprehensive understanding of how the antibacterial pathways opted by the MoS2 nanosheets varies with change in lipid compositions of different bacterial strains is imperative to harness their full antibacterial potential and remains unexplored thus far. Herein, we present an atomistic molecular dynamics (MD) study to investigate the distinct modes of antibacterial action of MoS2 nanosheets against Staphylococcus aureus (S. aureus) under varying conditions. We observed that the freely dispersed nanosheets readily adhered to the bacterial membrane outer surface and opted for an unconventional surface directed "wrapping-trapping" mechanism at physiological temperature (i.e., 310 K). The adsorbed nanosheets mildly influenced the membrane structure by originating a compact packing of the lipid molecules present in its direct contact. Interestingly, these surface adsorbed nanosheets exhibited extensive phospholipid extraction to their surface, thereby inducing transmembrane water passage analogous to the cellular leakage, even at a slight increment of 20 K in the temperature. The strong van der Waals interactions between lipid fatty acyl tails and MoS2 basal planes were primarily responsible for this destructive phospholipid extraction. In addition, the MoS2 nanosheets bound to an imaginary substrate, controlling their vertical alignment, demonstrated a "nano-knives" action by spontaneously piercing inside the membrane core through their sharp corner, subsequently causing localized lipid ordering in their vicinity. The larger nanosheet produced a more profound deteriorating impact in all of the observed mechanisms. Keeping the existing knowledge about the bactericidal activity of 2D MoS2 in view, our study concludes that their antibacterial activity is strongly governed by the lipid composition of the bacterial membrane and can be intensified either by controlling the nanosheet vertical alignment or by moderately warming up the systems.
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Affiliation(s)
- Monika Kumari
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Hemant K Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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8
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Luyet C, Elvati P, Vinh J, Violi A. Low-THz Vibrations of Biological Membranes. MEMBRANES 2023; 13:membranes13020139. [PMID: 36837641 PMCID: PMC9965665 DOI: 10.3390/membranes13020139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/04/2023] [Accepted: 01/17/2023] [Indexed: 05/12/2023]
Abstract
A growing body of work has linked key biological activities to the mechanical properties of cellular membranes, and as a means of identification. Here, we present a computational approach to simulate and compare the vibrational spectra in the low-THz region for mammalian and bacterial membranes, investigating the effect of membrane asymmetry and composition, as well as the conserved frequencies of a specific cell. We find that asymmetry does not impact the vibrational spectra, and the impact of sterols depends on the mobility of the components of the membrane. We demonstrate that vibrational spectra can be used to distinguish between membranes and, therefore, could be used in identification of different organisms. The method presented, here, can be immediately extended to other biological structures (e.g., amyloid fibers, polysaccharides, and protein-ligand structures) in order to fingerprint and understand vibrations of numerous biologically-relevant nanoscale structures.
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Affiliation(s)
- Chloe Luyet
- Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA
| | - Paolo Elvati
- Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA
| | - Jordan Vinh
- Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA
| | - Angela Violi
- Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA
- Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA
- Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109-2125, USA
- Correspondence:
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9
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Joodaki F, Martin LM, Greenfield ML. Generation and Computational Characterization of a Complex Staphylococcus aureus Lipid Bilayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9481-9499. [PMID: 35901279 DOI: 10.1021/acs.langmuir.2c00483] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Studies indicate a crucial cell membrane role in the antibiotic resistance of Staphylococcus aureus. To simulate its membrane structure and dynamics, a complex molecular-scale computational representation of the S. aureus lipid bilayer was developed. Phospholipid types and their amounts were optimized by reverse Monte Carlo to represent characterization data from the literature, leading to 19 different phospholipid types that combine three headgroups [phosphatidylglycerol, lysyl-phosphatidylglycerol (LPG), and cardiolipin] and 10 tails, including iso- and anteiso-branched saturated chains. The averaged lipid bilayer thickness was 36.7 Å, and area per headgroup was 67.8 Å2. Phosphorus and nitrogen density profiles showed that LPG headgroups tended to be bent and oriented more parallel to the bilayer plane. The water density profile showed that small amounts reached the membrane center. Carbon density profiles indicated hydrophobic interactions for all lipids in the middle of the bilayer. Bond vector order parameters along each tail demonstrated different C-H ordering even within distinct lipids of the same type; however, all tails followed similar trends in average order parameter. These complex simulations further revealed bilayer insights beyond those attainable with monodisperse, unbranched lipids. Longer tails often extended into the opposite leaflet. Carbon at and beyond a branch showed significantly decreased ordering compared to carbon in unbranched tails; this feature arose in every branched lipid. Diverse tail lengths distributed these disordered methyl groups throughout the middle third of the bilayer. Distributions in mobility and ordering reveal diverse properties that cannot be obtained with monodisperse lipids.
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Affiliation(s)
- Faramarz Joodaki
- Department of Chemical Engineering, University of Rhode Island, 360 Fascitelli Center for Advanced Engineering, Kingston, Rhode Island 02881, United States
| | - Lenore M Martin
- Department of Cell and Molecular Biology, University of Rhode Island, 120 Flagg Road, Kingston, Rhode Island 02881, United States
| | - Michael L Greenfield
- Department of Chemical Engineering, University of Rhode Island, 360 Fascitelli Center for Advanced Engineering, Kingston, Rhode Island 02881, United States
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Kumari M, Roy S, Jaiswal A, Kashyap HK. Anionic Lipid Clustering-Mediated Bactericidal Activity and Selective Toxicity of Quaternary Ammonium-Substituted Polycationic Pullulan against the Staphylococcus aureus Bacterial Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:8065-8076. [PMID: 35731708 DOI: 10.1021/acs.langmuir.2c00871] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Non-amphiphilic polycations have recently been recognized to hold excellent antimicrobial potential with great mammalian cell compatibility. In a recent study, the excellent broad-spectrum bactericidal efficacy of a quaternary ammonium-substituted cationic pullulan (CP4) was demonstrated. Their selective toxicity and nominal probability to induce the acquisition of resistance among pathogens fulfill the fundamental requirements of new-generation antibacterials. However, there have been exiguous attempts in the literature to understand the antimicrobial activity of polycations against Gram-positive bacterial membranes. Here, for the first time, we have scrutinized the molecular level interactions of CP4 tetramers with a model Staphylococcus aureus membrane to understand their probable antibacterial function using molecular dynamics simulations. Our analysis reveals that the hydrophilic CP4 molecules are spontaneously adsorbed onto the membrane outer leaflet surface by virtue of strong electrostatic interactions and do not penetrate into the lipid tail hydrophobic region. This surface binding of CP4 is strengthened by the formation of anionic lipid-rich domains in their vicinity, causing lateral compositional heterogeneity. The major outcomes of the asymmetric accumulation of bulky polycationic CP4 on one leaflet are (i) anionic lipid segregation at the interaction site and (ii) a decrease in the cationic lipid acyl tail ordering and ease of water translocation across the lipid hydrophobic barrier. The membrane-CP4 interactions are strongly monitored by the ionic strength; a higher salt concentration weakens the binding of CP4 on the membrane surface. In addition, our study also substantiates the non-interacting behavior of CP4 oligomers with biomimetic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membrane, indicating their cell selectivity and specificity against pathogenic membranes.
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Affiliation(s)
- Monika Kumari
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Shounak Roy
- School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh 175075, India
| | - Amit Jaiswal
- School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh 175075, India
| | - Hemant K Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Chen H, Qiu C, Jiang Y, Liao X, Wu D, Shen M, Ding T. Silver nanoparticles on UiO-66 (Zr) metal-organic frameworks for water disinfection application. FOOD SCIENCE AND HUMAN WELLNESS 2022. [DOI: 10.1016/j.fshw.2021.11.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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12
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Parra-Ortiz E, Malmsten M. Photocatalytic nanoparticles - From membrane interactions to antimicrobial and antiviral effects. Adv Colloid Interface Sci 2022; 299:102526. [PMID: 34610862 DOI: 10.1016/j.cis.2021.102526] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 12/23/2022]
Abstract
As a result of increasing resistance among pathogens against antibiotics and anti-viral therapeutics, nanomaterials are attracting current interest as antimicrobial agents. Such materials offer triggered functionalities to combat challenging infections, based on either direct membrane action, effects of released ions, thermal shock induced by either light or magnetic fields, or oxidative photocatalysis. In the present overview, we focus on photocatalytic antimicrobial effects, in which light exposure triggers generation of reactive oxygen species. These, in turn, cause oxidative damage to key components in bacteria and viruses, including lipid membranes, lipopolysaccharides, proteins, and DNA/RNA. While an increasing body of studies demonstrate that potent antimicrobial effects can be achieved by photocatalytic nanomaterials, understanding of the mechanistic foundation underlying such effects is still in its infancy. Addressing this, we here provide an overview of the current understanding of the interaction of photocatalytic nanomaterials with pathogen membranes and membrane components, and how this translates into antibacterial and antiviral effects.
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Affiliation(s)
- Elisa Parra-Ortiz
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Martin Malmsten
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark; Physical Chemistry 1, University of Lund, S-221 00 Lund, Sweden.
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A combined FTIR and DSC study on the bilayer-stabilising effect of electrostatic interactions in ion paired lipids. Colloids Surf B Biointerfaces 2018; 169:298-304. [DOI: 10.1016/j.colsurfb.2018.05.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 05/11/2018] [Accepted: 05/14/2018] [Indexed: 11/23/2022]
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14
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Punekar AS, Samsudin F, Lloyd AJ, Dowson CG, Scott DJ, Khalid S, Roper DI. The role of the jaw subdomain of peptidoglycan glycosyltransferases for lipid II polymerization. Cell Surf 2018; 2:54-66. [PMID: 30046666 PMCID: PMC6053601 DOI: 10.1016/j.tcsw.2018.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/12/2018] [Accepted: 06/12/2018] [Indexed: 12/27/2022] Open
Abstract
Bacterial peptidoglycan glycosyltransferases (PGT) catalyse the essential polymerization of lipid II into linear glycan chains required for peptidoglycan biosynthesis. The PGT domain is composed of a large head subdomain and a smaller jaw subdomain and can be potently inhibited by the antibiotic moenomycin A (MoeA). We present an X-ray structure of the MoeA-bound Staphylococcus aureus monofunctional PGT enzyme, revealing electron density for a second MoeA bound to the jaw subdomain as well as the PGT donor site. Isothermal titration calorimetry confirms two drug-binding sites with markedly different affinities and positive cooperativity. Hydrophobic cluster analysis suggests that the membrane-interacting surface of the jaw subdomain has structural and physicochemical properties similar to amphipathic cationic α -helical antimicrobial peptides for lipid II recognition and binding. Furthermore, molecular dynamics simulations of the drug-free and -bound forms of the enzyme demonstrate the importance of the jaw subdomain movement for lipid II selection and polymerization process and provide molecular-level insights into the mechanism of peptidoglycan biosynthesis by PGTs.
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Affiliation(s)
- Avinash S. Punekar
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Firdaus Samsudin
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Adrian J. Lloyd
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | | | - David J. Scott
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, United Kingdom
- ISIS Neutron and Muon Spallation Source and Research Complex at Harwell, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - David I. Roper
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
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15
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Fields RN, Roy H. Deciphering the tRNA-dependent lipid aminoacylation systems in bacteria: Novel components and structural advances. RNA Biol 2017; 15:480-491. [PMID: 28816600 PMCID: PMC6103681 DOI: 10.1080/15476286.2017.1356980] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
tRNA-dependent addition of amino acids to lipids on the outer surface of the bacterial membrane results in decreased effectiveness of antimicrobials such as cationic antimicrobial peptides (CAMPs) that target the membrane, and increased virulence of several pathogenic species. After a brief introduction to CAMPs and the various bacterial resistance mechanisms used to counteract these compounds, this review focuses on recent advances in tRNA-dependent pathways for lipid modification in bacteria. Phenotypes associated with amino acid lipid modifications and regulation of their expression will also be discussed.
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Affiliation(s)
- Rachel N Fields
- a Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando , Florida , United States of America
| | - Hervé Roy
- a Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando , Florida , United States of America
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16
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Lynch M, Marinov GK. Membranes, energetics, and evolution across the prokaryote-eukaryote divide. eLife 2017; 6:20437. [PMID: 28300533 PMCID: PMC5354521 DOI: 10.7554/elife.20437] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 01/17/2017] [Indexed: 12/19/2022] Open
Abstract
The evolution of the eukaryotic cell marked a profound moment in Earth’s history, with most of the visible biota coming to rely on intracellular membrane-bound organelles. It has been suggested that this evolutionary transition was critically dependent on the movement of ATP synthesis from the cell surface to mitochondrial membranes and the resultant boost to the energetic capacity of eukaryotic cells. However, contrary to this hypothesis, numerous lines of evidence suggest that eukaryotes are no more bioenergetically efficient than prokaryotes. Thus, although the origin of the mitochondrion was a key event in evolutionary history, there is no reason to think membrane bioenergetics played a direct, causal role in the transition from prokaryotes to eukaryotes and the subsequent explosive diversification of cellular and organismal complexity. Over time, life on Earth has evolved into three large groups: archaea, bacteria, and eukaryotes. The most familiar forms of life – such as fungi, plants and animals – all belong to the eukaryotes. Bacteria and archaea are simpler, single-celled organisms and are collectively referred to as prokaryotes. The hallmark feature that distinguishes eukaryotes from prokaryotes is that eukaryotic cells contain compartments called organelles that are surrounded by membranes. Each organelle supports different activities in the cell. Mitochondria, for example, are organelles that provide eukaryotes with most of their energy by producing energy-rich molecules called ATP. Prokaryotes lack mitochondria and instead produce their ATP on their cell surface membrane. Some researchers have suggested that mitochondria might actually be one of the reasons that eukaryotic cells are typically larger than prokaryotes and more varied in their shape and structure. The thinking is that producing ATP on dedicated membranes inside the cell, rather than on the cell surface, boosted the amount of energy available to eukaryotic cells and allowed them to diversify more. However, other researchers are not convinced by this view. Moreover, some recent evidence suggested that eukaryotes are no more efficient in producing energy than prokaryotes. Lynch and Marinov have now used computational and comparative analysis to compare the energy efficiency of different organisms including prokaryotes and eukaryotes grown under defined conditions. To do the comparison, the results were scaled based on cell volume and the total surface area deployed in energy production. From their findings, Lynch and Marinov concluded that mitochondria did not enhance how much energy eukaryotes could produce per unit of cell volume in any substantial way. Although the origin of mitochondria was certainly a key event in evolutionary history, it is unlikely to have been responsible for the diversity and complexity of today’s life forms.
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Affiliation(s)
- Michael Lynch
- Department of Biology, Indiana University, Bloomington, United States
| | - Georgi K Marinov
- Department of Biology, Indiana University, Bloomington, United States
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17
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Slavetinsky C, Kuhn S, Peschel A. Bacterial aminoacyl phospholipids - Biosynthesis and role in basic cellular processes and pathogenicity. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:1310-1318. [PMID: 27940309 DOI: 10.1016/j.bbalip.2016.11.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Revised: 11/28/2016] [Accepted: 11/30/2016] [Indexed: 10/20/2022]
Abstract
The bacterial cell membrane accomplishes the controlled exchange of molecules with the extracellular space and mediates specific interactions with the environment. However, the cytoplasmic membrane also includes vulnerable targets for antimicrobial agents. A common feature of cationic antimicrobial peptides (CAMPs) produced by other bacteria or by the host immune system is to utilize the negative charge of bacterial phospholipids such as phosphatidylglycerol (PG) or cardiolipin (CL) for initial adherence and subsequent penetration into the membrane bilayer. To resist cationic antimicrobials many bacteria integrate positive charges into the membrane surface. This is accomplished by aminoacylation of negatively charged (PG) or (CL) with alanine, arginine, or lysine residues. The Multiple Peptide Resistance Factor (MprF) of Staphylococcus aureus is the prototype of a highly conserved protein family of aminoacyl phosphatidylglycerol synthases (aaPGSs) which modify PG or CL with amino acids. MprF is an oligomerizing membrane protein responsible for both, synthesis of lysyl phosphatidylglycerol (LysPG) in the inner leaflet of the cytoplasmic membrane and translocation of LysPG to the outer leaflet. This review focuses on occurrence, synthesis and function of bacterial aminoacyl phospholipids (aaPLs) and on the role of such lipids in basic cellular processes and pathogenicity. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
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Affiliation(s)
- Christoph Slavetinsky
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany
| | - Sebastian Kuhn
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany
| | - Andreas Peschel
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany.
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18
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Rice DR, Clear KJ, Smith BD. Imaging and therapeutic applications of zinc(ii)-dipicolylamine molecular probes for anionic biomembranes. Chem Commun (Camb) 2016; 52:8787-801. [PMID: 27302091 PMCID: PMC4949593 DOI: 10.1039/c6cc03669d] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This feature article describes the development of synthetic zinc(ii)-dipicolylamine (ZnDPA) receptors as selective targeting agents for anionic membranes in cell culture and living subjects. There is a strong connection between anionic cell surface charge and disease, and ZnDPA probes have been employed extensively for molecular imaging and targeted therapeutics. Fluorescence and nuclear imaging applications include detection of diseases such as cancer, neurodegeneration, arthritis, and microbial infection, and also quantification of cell death caused by therapy. Therapeutic applications include selective targeting of cytotoxic agents and drug delivery systems, photodynamic inactivation, and modulation of the immune system. The article concludes with a summary of expected future directions.
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Affiliation(s)
- Douglas R Rice
- Department of Chemistry and Biochemistry, 236 Nieuwland Science Hall, University of Notre Dame, Notre Dame, 46556 IN, USA.
| | - Kasey J Clear
- Department of Chemistry and Biochemistry, 236 Nieuwland Science Hall, University of Notre Dame, Notre Dame, 46556 IN, USA.
| | - Bradley D Smith
- Department of Chemistry and Biochemistry, 236 Nieuwland Science Hall, University of Notre Dame, Notre Dame, 46556 IN, USA.
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19
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Dennison SR, Morton LH, Harris F, Phoenix DA. Low pH Enhances the Action of Maximin H5 against Staphylococcus aureus and Helps Mediate Lysylated Phosphatidylglycerol-Induced Resistance. Biochemistry 2016; 55:3735-51. [PMID: 27336672 DOI: 10.1021/acs.biochem.6b00101] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Maximin H5 (MH5) is an amphibian antimicrobial peptide specifically targeting Staphylococcus aureus. At pH 6, the peptide showed an improved ability to penetrate (ΔΠ = 6.2 mN m(-1)) and lyse (lysis = 48%) Staphylococcus aureus membrane mimics, which incorporated physiological levels of lysylated phosphatidylglycerol (Lys-PG, 60%), compared to that at pH 7 (ΔΠ = 5.6 mN m(-1) and lysis = 40% at pH 7) where levels of Lys-PG are lower (40%). The peptide therefore appears to have optimal function at pH levels known to be optimal for the organism's growth. MH5 killed S. aureus (minimum inhibitory concentration of 90 μM) via membranolytic mechanisms that involved the stabilization of α-helical structure (approximately 45-50%) and showed similarities to the "Carpet" mechanism based on its ability to increase the rigidity (Cs(-1) = 109.94 mN m(-1)) and thermodynamic stability (ΔGmix = -3.0) of physiologically relevant S. aureus membrane mimics at pH 6. On the basis of theoretical analysis, this mechanism might involve the use of a tilted peptide structure, and efficacy was noted to vary inversely with the Lys-PG content of S. aureus membrane mimics for each pH studied (R(2) ∼ 0.97), which led to the suggestion that under biologically relevant conditions, low pH helps mediate Lys-PG-induced resistance in S. aureus to MH5 antibacterial action. The peptide showed a lack of hemolytic activity (<2% hemolysis) and merits further investigation as a potential template for development as an antistaphylococcal agent in medically and biotechnically relevant areas.
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Affiliation(s)
- Sarah R Dennison
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire , Preston PR1 2HE, U.K
| | - Leslie Hg Morton
- School of Forensic and Investigative Science, University of Central Lancashire , Preston PR1 2HE, U.K
| | - Frederick Harris
- School of Forensic and Investigative Science, University of Central Lancashire , Preston PR1 2HE, U.K
| | - David A Phoenix
- School of Applied Science, London South Bank University , 103 Borough Road, London SE1 0AA, U.K
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20
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Witzke S, Petersen M, Carpenter TS, Khalid S. Molecular Dynamics Simulations Reveal the Conformational Flexibility of Lipid II and Its Loose Association with the Defensin Plectasin in the Staphylococcus aureus Membrane. Biochemistry 2016; 55:3303-14. [PMID: 27158738 DOI: 10.1021/acs.biochem.5b01315] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lipid II is critical for peptidoglycan synthesis, which is the main component of the bacterial cell wall. Lipid II is a relatively conserved and important part of the cell wall biosynthesis pathway and is targeted by antibiotics such as the lantibiotics, which achieve their function by disrupting the biosynthesis of the cell wall. Given the urgent need for development of novel antibiotics to counter the growing threat of bacterial infection resistance, it is imperative that a thorough molecular-level characterization of the molecules targeted by antibiotics be achieved. To this end, we present a molecular dynamics simulation study of the conformational dynamics of Lipid II within a detailed model of the Staphylococcus aureus cell membrane. We show that Lipid II is able to adopt a range of conformations, even within the packed lipidic environment of the membrane. Our simulations also reveal dimerization of Lipid II mediated by cations. In the presence of the defensin peptide plectasin, the conformational lability of Lipid II allows it to form loose complexes with the protein, via a number of different binding modes.
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Affiliation(s)
- Sarah Witzke
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Odense, Denmark.,School of Chemistry, University of Southampton , Highfield, Southampton SO17 1BJ, U.K
| | - Michael Petersen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Odense, Denmark
| | - Timothy S Carpenter
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory , 7000 East Avenue, Livermore, California 94550, United States
| | - Syma Khalid
- School of Chemistry, University of Southampton , Highfield, Southampton SO17 1BJ, U.K
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21
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Parkin J, Chavent M, Khalid S. Molecular Simulations of Gram-Negative Bacterial Membranes: A Vignette of Some Recent Successes. Biophys J 2016; 109:461-8. [PMID: 26244728 DOI: 10.1016/j.bpj.2015.06.050] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/09/2015] [Accepted: 06/24/2015] [Indexed: 01/05/2023] Open
Abstract
In the following review we use recent examples from the literature to discuss progress in the area of atomistic and coarse-grained molecular dynamics simulations of selected bacterial membranes and proteins, with a particular focus on Gram-negative bacteria. As structural biology continues to provide increasingly high-resolution data on the proteins that reside within these membranes, simulations have an important role to play in linking these data with the dynamical behavior and function of these proteins. In particular, in the last few years there has been significant progress in addressing the issue of biochemical complexity of bacterial membranes such that the heterogeneity of the lipid and protein components of these membranes are now being incorporated into molecular-level models. Thus, in future we can look forward to complementary data from structural biology and molecular simulations combining to provide key details of structure-dynamics-function relationships in bacterial membranes.
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Affiliation(s)
- Jamie Parkin
- School of Chemistry, University of Southampton, Southampton, UK
| | | | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton, UK.
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22
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Smith AM, Harrison JS, Grube CD, Sheppe AEF, Sahara N, Ishii R, Nureki O, Roy H. tRNA-dependent alanylation of diacylglycerol and phosphatidylglycerol in Corynebacterium glutamicum. Mol Microbiol 2015; 98:681-93. [PMID: 26235234 DOI: 10.1111/mmi.13150] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2015] [Indexed: 12/12/2022]
Abstract
Aminoacyl-phosphatidylglycerol synthases (aaPGSs) are membrane proteins that utilize aminoacylated tRNAs to modify membrane lipids with amino acids. Aminoacylation of membrane lipids alters the biochemical properties of the cytoplasmic membrane and enables bacteria to adapt to changes in environmental conditions. aaPGSs utilize alanine, lysine and arginine as modifying amino acids, and the primary lipid recipients have heretofore been defined as phosphatidylglycerol (PG) and cardiolipin. Here we identify a new pathway for lipid aminoacylation, conserved in many Actinobacteria, which results in formation of Ala-PG and a novel alanylated lipid, Alanyl-diacylglycerol (Ala-DAG). Ala-DAG formation in Corynebacterium glutamicum is dependent on the activity of an aaPGS homolog, whereas formation of Ala-PG requires the same enzyme acting in concert with a putative esterase encoded upstream. The presence of alanylated lipids is sufficient to enhance the bacterial fitness of C. glutamicum cultured in the presence of certain antimicrobial agents, and elucidation of this system expands the known repertoire of membrane lipids acting as substrates for amino acid modification in bacterial cells.
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Affiliation(s)
- Angela M Smith
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
| | - Jesse S Harrison
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
| | - Christopher D Grube
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
| | - Austin E F Sheppe
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
| | - Nahoko Sahara
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, 113-0033, Tokyo, Japan.,RIKEN Advanced Science Institute, Wako-shi, 351-0198, Saitama, Japan
| | - Ryohei Ishii
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, 113-0033, Tokyo, Japan.,RIKEN Advanced Science Institute, Wako-shi, 351-0198, Saitama, Japan
| | - Osamu Nureki
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, 113-0033, Tokyo, Japan.,RIKEN Advanced Science Institute, Wako-shi, 351-0198, Saitama, Japan
| | - Hervé Roy
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32826, USA
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23
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Abstract
With increasing antibiotics resistance, there is an urgent need for novel infection therapeutics. Since antimicrobial peptides provide opportunities for this, identification and optimization of such peptides have attracted much interest during recent years. Here, a brief overview of antimicrobial peptides is provided, with focus placed on how selected hydrophobic modifications of antimicrobial peptides can be employed to combat also more demanding pathogens, including multi-resistant strains, without conferring unacceptable toxicity.
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24
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Dare K, Shepherd J, Roy H, Seveau S, Ibba M. LysPGS formation in Listeria monocytogenes has broad roles in maintaining membrane integrity beyond antimicrobial peptide resistance. Virulence 2014; 5:534-46. [PMID: 24603093 DOI: 10.4161/viru.28359] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Listeria monocytogenes is an intracellular, foodborne gastrointestinal pathogen that is primarily responsible for causing listeriosis or food poisoning in otherwise healthy individuals. Infections that arise during pregnancy or within immune compromised individuals are much more serious resulting in the risk of fetal termination or fetal fatality postpartum in the former and septicemia or meningitis with a 20% fatality rate in the latter. While the roles of internalin proteins and listeriolysin-O in the infection process are well characterized, the specific roles of lysine-modified phospholipids in the membrane of L. monocytogenes are not. Investigation into the lipid bilayer composition of L. monocytogenes indicated that the overall proportions of lipids, including lysylcardiolipin and lysylphosphatidylglycerol (LysPG), vary with growth temperature and growth phase. In addition, we demonstrate that LysPG formation is essential for L. monocytogenes survival in the presence of increased osmolytic stress but has no effect on bacterial adherence, invasion or survival in the presence of physiologically relevant concentrations of human neutrophil peptide (HNP-1). In the absence of LysPG synthesis, L. monocytogenes unexpectedly retained flagellum-mediated motility at 37 °C. Taken together, these findings show that LysPG formation in L. monocytogenes has broader functions in virulence and survival beyond its known role in the modification of membrane potential previously observed in other bacteria.
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Affiliation(s)
- Kiley Dare
- Department of Microbiology; The Ohio State University; Columbus, OH USA
| | - Jennifer Shepherd
- Department of Microbiology; The Ohio State University; Columbus, OH USA
| | - Hervé Roy
- Department of Microbiology; The Ohio State University; Columbus, OH USA
| | - Stephanie Seveau
- Department of Microbiology; The Ohio State University; Columbus, OH USA
| | - Michael Ibba
- Department of Microbiology; The Ohio State University; Columbus, OH USA; Ohio State Biochemistry Program; Center for RNA Biology; The Ohio State University; Columbus, OH USA
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25
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Schmidtchen A, Pasupuleti M, Malmsten M. Effect of hydrophobic modifications in antimicrobial peptides. Adv Colloid Interface Sci 2014; 205:265-74. [PMID: 23910480 DOI: 10.1016/j.cis.2013.06.009] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 06/17/2013] [Accepted: 06/27/2013] [Indexed: 11/18/2022]
Abstract
With increasing resistance development against conventional antibiotics, there is an urgent need to identify novel approaches for infection treatment. Antimicrobial peptides may offer opportunities in this context, hence there has been considerable interest in identification and optimization of such peptides during the last decade in particular, with the long-term aim of developing these to potent and safe therapeutics. In the present overview, focus is placed on hydrophobic modifications of antimicrobial peptides, and how these may provide opportunities to combat also more demanding pathogens, including multi-resistant strains, yet not provoking unacceptable toxic responses. In doing so, physicochemical factors affecting peptide interactions with bacterial and eukaryotic cell membranes are discussed. Throughout, an attempt is made to illustrate how physicochemical studies on model lipid membranes can be correlated to result from bacterial and cell assays, and knowledge from this translated into therapeutic considerations.
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Affiliation(s)
- Artur Schmidtchen
- Section of Dermatology and Venereology, Department of Clinical Sciences, Lund University, SE-221 84 Lund, Sweden
| | - Mukesh Pasupuleti
- Section of Dermatology and Venereology, Department of Clinical Sciences, Lund University, SE-221 84 Lund, Sweden
| | - Martin Malmsten
- Department of Pharmacy, Uppsala University, P.O. Box 580, SE-751 23 Uppsala, Sweden.
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26
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Taylor PW. Alternative natural sources for a new generation of antibacterial agents. Int J Antimicrob Agents 2013; 42:195-201. [DOI: 10.1016/j.ijantimicag.2013.05.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/13/2013] [Indexed: 10/26/2022]
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27
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Smith AM, Harrison JS, Sprague KM, Roy H. A conserved hydrolase responsible for the cleavage of aminoacylphosphatidylglycerol in the membrane of Enterococcus faecium. J Biol Chem 2013; 288:22768-76. [PMID: 23793054 DOI: 10.1074/jbc.m113.484402] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aminoacylphosphatidylglycerol synthases (aaPGSs) are enzymes that transfer amino acids from aminoacyl-tRNAs (aa-tRNAs) to phosphatidylglycerol (PG) to form aa-PG in the cytoplasmic membrane of bacteria. aa-PGs provide bacteria with resistance to a range of antimicrobial compounds and stress conditions. Enterococcus faecium encodes a triple-specific aaPGS (RakPGS) that utilizes arginine, alanine, and lysine as substrates. Here we identify a novel hydrolase (AhyD), encoded immediately adjacent to rakPGS in E. faecium, which is responsible for the hydrolysis of aa-PG. The genetic synteny of aaPGS and ahyD is conserved in >60 different bacterial species. Deletion of ahyD in E. faecium resulted in increased formation of Ala-PG and Lys-PG and increased sensitivity to bacitracin. Our results suggest that AhyD and RakPGS act together to maintain optimal levels of aa-PG in the bacterial membrane to confer resistance to certain antimicrobial compounds and stress conditions.
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Affiliation(s)
- Angela M Smith
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32826, USA
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28
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Dare K, Ibba M. Roles of tRNA in cell wall biosynthesis. WILEY INTERDISCIPLINARY REVIEWS. RNA 2012; 3:247-64. [PMID: 22262511 PMCID: PMC3873719 DOI: 10.1002/wrna.1108] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Recent research into various aspects of bacterial metabolism such as cell wall and antibiotic synthesis, degradation pathways, cellular stress, and amino acid biosynthesis has elucidated roles of aminoacyl-transfer ribonucleic acid (aa-tRNA) outside of translation. Although the two enzyme families responsible for cell wall modifications, aminoacyl-phosphatidylglycerol synthases (aaPGSs) and Fem, were discovered some time ago, they have recently become of intense interest for their roles in the antimicrobial resistance of pathogenic microorganisms. The addition of positively charged amino acids to phosphatidylglycerol (PG) by aaPGSs neutralizes the lipid bilayer making the bacteria less susceptible to positively charged antimicrobial agents. Fem transferases utilize aa-tRNA to form peptide bridges that link strands of peptidoglycan. These bridges vary among the bacterial species in which they are present and play a role in resistance to antibiotics that target the cell wall. Additionally, the formation of truncated peptides results in shorter peptide bridges and loss of branched linkages which makes bacteria more susceptible to antimicrobials. A greater understanding of the structure and substrate specificity of this diverse enzymatic family is necessary to aid current efforts in designing potential bactericidal agents. These two enzyme families are linked only by the substrate with which they modify the cell wall, aa-tRNA; their structure, cell wall modification processes and the physiological changes they impart on the bacterium differ greatly.
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Affiliation(s)
- Kiley Dare
- Department of Microbiology, Ohio State University, Columbus, OH, USA
| | - Michael Ibba
- Department of Microbiology, Ohio State University, Columbus, OH, USA
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29
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Pasupuleti M, Schmidtchen A, Malmsten M. Antimicrobial peptides: key components of the innate immune system. Crit Rev Biotechnol 2011; 32:143-71. [PMID: 22074402 DOI: 10.3109/07388551.2011.594423] [Citation(s) in RCA: 494] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Life-threatening infectious diseases are on their way to cause a worldwide crisis, as treating them effectively is becoming increasingly difficult due to the emergence of antibiotic resistant strains. Antimicrobial peptides (AMPs) form an ancient type of innate immunity found universally in all living organisms, providing a principal first-line of defense against the invading pathogens. The unique diverse function and architecture of AMPs has attracted considerable attention by scientists, both in terms of understanding the basic biology of the innate immune system, and as a tool in the design of molecular templates for new anti-infective drugs. AMPs are gene-encoded short (<100 amino acids), amphipathic molecules with hydrophobic and cationic amino acids arranged spatially, which exhibit broad spectrum antimicrobial activity. AMPs have been the subject of natural evolution, as have the microbes, for hundreds of millions of years. Despite this long history of co-evolution, AMPs have not lost their ability to kill or inhibit the microbes totally, nor have the microbes learnt to avoid the lethal punch of AMPs. AMPs therefore have potential to provide an important breakthrough and form the basis for a new class of antibiotics. In this review, we would like to give an overview of cationic antimicrobial peptides, origin, structure, functions, and mode of action of AMPs, which are highly expressed and found in humans, as well as a brief discussion about widely abundant, well characterized AMPs in mammals, in addition to pharmaceutical aspects and the additional functions of AMPs.
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Affiliation(s)
- Mukesh Pasupuleti
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, Canada.
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30
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Piggot TJ, Holdbrook DA, Khalid S. Electroporation of the E. coli and S. Aureus Membranes: Molecular Dynamics Simulations of Complex Bacterial Membranes. J Phys Chem B 2011; 115:13381-8. [DOI: 10.1021/jp207013v] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thomas J. Piggot
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Daniel A. Holdbrook
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Syma Khalid
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
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31
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Schmidtchen A, Ringstad L, Kasetty G, Mizuno H, Rutland MW, Malmsten M. Membrane selectivity by W-tagging of antimicrobial peptides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1081-91. [DOI: 10.1016/j.bbamem.2010.12.020] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/16/2010] [Accepted: 12/20/2010] [Indexed: 10/18/2022]
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32
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33
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Sievers S, Ernst CM, Geiger T, Hecker M, Wolz C, Becher D, Peschel A. Changing the phospholipid composition of Staphylococcus aureus causes distinct changes in membrane proteome and membrane-sensory regulators. Proteomics 2010; 10:1685-93. [PMID: 20162562 DOI: 10.1002/pmic.200900772] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The dynamic lipid composition of bacterial cytoplasmic membranes has a profound impact on vital bacterial fitness and susceptibility to membrane-damaging agents, temperature, or osmotic stress. However, it has remained largely unknown how changes in lipid patterns affect the abundance and expression of membrane proteins. Using recently developed gel-free proteomics technology, we explored the membrane proteome of the important human pathogen Staphylococcus aureus in the presence or absence of the cationic phospholipid lysyl-phosphatidylglycerol (Lys-PG). We were able to detect almost half of all theoretical integral membrane proteins and could reliably quantify more than 35% of them. It is worth noting that the deletion of the Lys-PG synthase MprF did not lead to a massive alteration but a very distinct up- or down-regulation of only 1.5 or 3.5% of the quantified proteins. Lys-PG deficiency had no major impact on the abundance of lipid-biosynthetic enzymes but significantly affected the amounts of the cell envelope stress-sensing regulatory proteins such as SaeS and MsrR, and of the SaeS-regulated proteins Sbi, Efb, and SaeP. These data indicate very critical interactions of membrane-sensory proteins with phospholipids and they demonstrate the power of membrane proteomics for the characterization of bacterial physiology and pathogenicity.
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Affiliation(s)
- Susanne Sievers
- Institute for Microbiology, Department of Microbial Physiology, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany.
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Bernal P, Lemaire S, Pinho MG, Mobashery S, Hinds J, Taylor PW. Insertion of epicatechin gallate into the cytoplasmic membrane of methicillin-resistant Staphylococcus aureus disrupts penicillin-binding protein (PBP) 2a-mediated beta-lactam resistance by delocalizing PBP2. J Biol Chem 2010; 285:24055-65. [PMID: 20516078 PMCID: PMC2911331 DOI: 10.1074/jbc.m110.114793] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epicatechin gallate (ECg) sensitizes methicillin-resistant Staphylococcus aureus (MRSA) to oxacillin and other beta-lactam agents; it also reduces the secretion of virulence-associated proteins, prevents biofilm formation, and induces gross morphological changes in MRSA cells without compromising the growth rate. MRSA is resistant to oxacillin because of the presence of penicillin-binding protein 2a (PBP2a), which allows peptidoglycan synthesis to continue after oxacillin-mediated acylation of native PBPs. We show that ECg binds predominantly to the cytoplasmic membrane (CM), initially decreasing the fluidity of the bilayer, and induces changes in gene expression indicative of an attempt to preserve and repair a compromised cell wall. On further incubation, the CM is reorganized; the amount of lysylphosphatidylglycerol is markedly reduced, with a concomitant increase in phosphatidylglycerol, and the proportion of branched chain fatty acids increases, resulting in a more fluid structure. We found no evidence that ECg modulates the enzymatic activity of PBP2a through direct binding to the protein but determined that PBP2 is delocalized from the FtsZ-anchored cell wall biosynthetic machinery at the septal division site following intercalation into the CM. We argue that many features of the ECg-induced phenotype can be explained by changes in the fluid dynamics of the CM.
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Affiliation(s)
- Patricia Bernal
- School of Pharmacy, University of London, London WC1N 1AX, United Kingdom
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35
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Mastronicolis SK, Berberi A, Diakogiannis I, Petrova E, Kiaki I, Baltzi T, Xenikakis P. Alteration of the phospho- or neutral lipid content and fatty acid composition in Listeria monocytogenes due to acid adaptation mechanisms for hydrochloric, acetic and lactic acids at pH 5.5 or benzoic acid at neutral pH. Antonie van Leeuwenhoek 2010; 98:307-16. [PMID: 20379849 PMCID: PMC2935972 DOI: 10.1007/s10482-010-9439-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 03/29/2010] [Indexed: 10/30/2022]
Abstract
This study provides a first approach to observe the effects on Listeria monocytogenes of cellular exposure to acid stress at low or neutral pH, notably how phospho- or neutral lipids are involved in this mechanism, besides the fatty acid profile alteration. A thorough investigation of the composition of polar and neutral lipids from L. monocytogenes grown at pH 5.5 in presence of hydrochloric, acetic and lactic acids, or at neutral pH 7.3 in presence of benzoic acid, is described relative to cells grown in acid-free medium. The results showed that only low pH values enhance the antimicrobial activity of an acid. We suggest that, irrespective of pH, the acid adaptation response will lead to a similar alteration in fatty acid composition [decreasing the ratio of branched chain/saturated straight fatty acids of total lipids], mainly originating from the neutral lipid class of adapted cultures. Acid adaptation in L. monocytogenes was correlated with a decrease in total lipid phosphorus and, with the exception of cells adapted to benzoic acid, this change in the amount of phosphorus reflected a higher content of the neutral lipid class. Upon acetic or benzoic acid stress the lipid phosphorus proportion was analysed in the main phospholipids present: cardiolipin, phosphatidylglycerol, phosphoaminolipid and phosphatidylinositol. Interestingly only benzoic acid had a dramatic effect on the relative quantities of these four phospholipids.
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Affiliation(s)
- Sofia K Mastronicolis
- Food Chemistry Laboratory, Department of Chemistry, University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece.
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36
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Roy H. Tuning the properties of the bacterial membrane with aminoacylated phosphatidylglycerol. IUBMB Life 2009; 61:940-53. [PMID: 19787708 DOI: 10.1002/iub.240] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The bacterial envelope is a semi-permeable barrier that protects the cell from the hostilities of the environment. To survive the ever-changing conditions of their surroundings, bacteria need to rapidly adjust the biochemical properties of their cellular envelope. Amino acid (aa) addition to phosphatidylglycerol (PG) of the membrane is one of the mechanisms used by bacteria to lower the net negative charge of their cellular envelope, thereby decreasing its affinity for several antibacterial agents such as the cationic antimicrobial peptides (CAMPs) produced by the innate immune response during host infection. This process requires the activity of an integral membrane protein, called aa-PG synthase (aaPGS), to transfer the aa of aminoacyl-tRNA (aa-tRNA) onto the PG of the membrane. aaPGSs constitute a new family of virulence factors that are found in a wide range of microorganisms. aa-PGs not only provide resistance to CAMPs but also to other classes of antibacterial agents and to environmental stresses such as those encountered during extreme osmotic or acidic conditions. This review will describe the known biochemical properties of aa-PGSs, their specificity for aa-tRNAs and phospholipids, and the growing repertoire of aa used as substrates by these enzymes. Their prevalence in bacteria and the phenotypes and modulations of membrane properties associated with these molecules will be addressed, as well as their regulation as a component of the envelope stress response system in certain bacteria.
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Affiliation(s)
- Hervé Roy
- Department of Microbiology, Ohio State Biochemistry Program, Center for RNA Biology, The Ohio State University, Columbus, OH 43210-1292, USA.
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Structure and thermotropic behavior of the Staphylococcus aureus lipid lysyl-dipalmitoylphosphatidylglycerol. Biophys J 2007; 94:2150-9. [PMID: 18055539 DOI: 10.1529/biophysj.107.123422] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have characterized the structural and thermotropic properties of one of the most important lipids in the cell membrane of Staphylococcus aureus, lysyl-dipalmitoylphosphatidylglycerol (lysyl-DPPG). applying differential scanning calorimetry and small- and wide-angle x-ray scattering. Microcalorimetry revealed that under physiological conditions (phosphate buffer, 20 mM NaPi, 130 mM NaCl, pH 7.4), the synthetic lysyl-DPPG resembles the features of the parent dipalmitoylphosphatidylglycerol (DPPG) with respect to its melting behavior. However, in contrast to DPPG, lowering the pH did not significantly affect the main transition temperature ( approximately 40 degrees C) of lysyl-DPPG, which can be explained by its difference in protonization because of the lysine group. X-ray experiments yielded the first information on chain packing and morphology of lysyl-DPPG. We found that lysyl-DPPG forms an interdigitated lamellar phase below the chain-melting transition. This can be explained by the large headgroup area of lysyl-DPPG as a result of its charged lysine group, especially if the headgroup is arranged parallel to the bilayer plane. Additionally, lysyl-DPPG degradation products, such as lysine and free fatty acids, had significant influences on the melting behavior and led to a multicomponent melting transition. Our results indicate that the degradation of lysyl-DPPG takes place mainly during the hydration process but also depends on lipid storage time, pH, and thermal treatment. Detailed temperature-resolved experiments at pH 5.0 demonstrated the formation of a lamellar gel phase with tilted hydrocarbon chains and a ripple phase, coexisting with the interdigitated lysyl-DPPG bilayers.
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Deuticke B. Properties and structural basis of simple diffusion pathways in the erythrocyte membrane. Rev Physiol Biochem Pharmacol 2005; 78:1-97. [PMID: 322240 DOI: 10.1007/bfb0027721] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Peschel A, Jack RW, Otto M, Collins LV, Staubitz P, Nicholson G, Kalbacher H, Nieuwenhuizen WF, Jung G, Tarkowski A, van Kessel KP, van Strijp JA. Staphylococcus aureus resistance to human defensins and evasion of neutrophil killing via the novel virulence factor MprF is based on modification of membrane lipids with l-lysine. J Exp Med 2001; 193:1067-76. [PMID: 11342591 PMCID: PMC2193429 DOI: 10.1084/jem.193.9.1067] [Citation(s) in RCA: 577] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Defensins, antimicrobial peptides of the innate immune system, protect human mucosal epithelia and skin against microbial infections and are produced in large amounts by neutrophils. The bacterial pathogen Staphylococcus aureus is insensitive to defensins by virtue of an unknown resistance mechanism. We describe a novel staphylococcal gene, mprF, which determines resistance to several host defense peptides such as defensins and protegrins. An mprF mutant strain was killed considerably faster by human neutrophils and exhibited attenuated virulence in mice, indicating a key role for defensin resistance in the pathogenicity of S. aureus. Analysis of membrane lipids demonstrated that the mprF mutant no longer modifies phosphatidylglycerol with l-lysine. As this unusual modification leads to a reduced negative charge of the membrane surface, MprF-mediated peptide resistance is most likely based on repulsion of the cationic peptides. Accordingly, inactivation of mprF led to increased binding of antimicrobial peptides by the bacteria. MprF has no similarity with genes of known function, but related genes were identified in the genomes of several pathogens including Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Enterococcus faecalis. MprF thus constitutes a novel virulence factor, which may be of general relevance for bacterial pathogens and represents a new target for attacking multidrug resistant bacteria.
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Affiliation(s)
- A Peschel
- Microbial Genetics, University of Tuebingen, 72076 Tuebingen, Germany.
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Affiliation(s)
- T Ganz
- Department of Medicine and the Department of Pathology, University of California at Los Angeles, School of Medicine, Los Angeles, California 90095, USA.
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41
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Booth IR. The regulation of intracellular pH in bacteria. NOVARTIS FOUNDATION SYMPOSIUM 1999; 221:19-28; discussions 28-37. [PMID: 10207911 DOI: 10.1002/9780470515631.ch3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The regulation of intracellular pH (pHi) in bacterial cells is achieved through control over cation (and anion) permeability. In addition to the active components of homeostasis there are contributions from essentially passive elements, such as the lipid composition of the membrane and the buffering capacity of the cytoplasm. Active homeostasis involves control over the movement of K+, Na+ and H+. Alterations in the membrane permeability for any of these cations may cause perturbation of homeostasis. In Escherichia coli this is exemplified by the controlled activation of K+ efflux systems by glutathione adducts leading to temporary acidification of the cytoplasm. This is achieved by sophisticated control over the KefB and KefC systems, and is tightly integrated with glutathione-dependent detoxification mechanisms. Such control over pHi facilitates survival of the cell following exposure to toxic electrophiles. The components of pH homeostasis will be reviewed and the molecular mechanisms, and role of, the KefB and KefC systems will be discussed.
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Affiliation(s)
- I R Booth
- Department of Molecular and Cell Biology, University of Aberdeen, Institute of Medical Sciences, Foresterhill, UK
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Drici-Cachon Z, Cavin J, Diviès C. Effect of pHand age of culture on cellular fatty acid composition of Leuconostoc oenos. Lett Appl Microbiol 1996. [DOI: 10.1111/j.1472-765x.1996.tb01172.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Russell NJ, Evans RI, ter Steeg PF, Hellemons J, Verheul A, Abee T. Membranes as a target for stress adaptation. Int J Food Microbiol 1995; 28:255-61. [PMID: 8750671 DOI: 10.1016/0168-1605(95)00061-5] [Citation(s) in RCA: 201] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- N J Russell
- Biochemistry Unit, School of Molecular and Medical Biosciences, University of Wales Cardiff, UK.
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Drucker DB, Abdullah N. Polar lipids of Staphylococcus strains analysed by fast atom bombardment mass spectrometry. THE JOURNAL OF APPLIED BACTERIOLOGY 1995; 79:219-24. [PMID: 7592118 DOI: 10.1111/j.1365-2672.1995.tb00938.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This study used fast atom bombardment mass spectrometry (FAB MS) to obtain detailed information on polar lipids of Staphylococcus by examining 23 isolates. Eighteen major anions were found in the range m/z 199-297, consistent with the presence of carboxylate anions. A further 21 major anions were found in the higher mass regions of m/z 609-805, consistent with the presence of phospholipid anions. In Staph. aureus, Staph. epidermidis, Staph. haemolyticus and Staph. hominis, the most intense peaks putatively assigned as carboxylate ions were consistent with presence of C15:0, followed by C17:0 except in the case of Staph. epidermidis. The major phospholipid anions were consistent with the presence of PG(30:0), PG(32:0) and PG(33:0). It is concluded that Staphylococcus has a characteristic polar lipid profile and that qualitative and quantitative differences may be seen between Staph. aureus and Staph. epidermidis.
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Affiliation(s)
- D B Drucker
- School of Biological Sciences, University of Manchester, UK
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45
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Abstract
The existing literature on the role of fatty acids in microbial temperature adaptation is reviewed. Several modes of change of cellular fatty acids at varying environmental temperatures are shown to exist in yeasts and fungi, Gram-negative bacteria, and bacteria containing iso- and anteiso-branched fatty acids, as well as in a few Gram-positive bacteria. Consequently, the degree of fatty acid unsaturation and cyclization, fatty acid chain length, branching, and cellular fatty acid content increase, decrease, or remain unaltered on lowering the temperature. Moreover, microorganisms seem to be able to change from one mode or alter the cellular fatty acid profile temperature dependently to another on lowering the temperature, as well as even within the same growth temperature range, depending on growth conditions. Therefore, the effect of the temperature on cellular fatty acids appears to be more complicated than known earlier. However, similarities found in the modes of change of cellular fatty acids at varying environmental temperatures in several microorganisms within the above mentioned groups support the existence of a limited amount of common regulatory mechanisms. The models presented enable the prediction of temperature-induced changes occurring in the fatty acids of microorganisms, and enzymatic steps of the fatty acid biosynthesis that possibly are under temperature control.
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Affiliation(s)
- M Suutari
- Helsinki University of Technology, Department of Chemical Engineering, Espoo, Finland
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46
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Abstract
In this overview liposomes are described as bilayer-bounded vesicles which under defined conditions act as ideal osmometers according to the Boyle van't Hoff law. Investigations on osmotic volume changes, directly or indirectly by taking advantage of changes in light scattering, are considered and applications in permeability measurements are discussed. Solute-solvent interactions occurring in isotonic swelling experiments are analysed in view of an irreversible thermodynamic description. In a second part liquid crystalline lipid bilayers are characterized as highly selective permeability bilayers and the physical principles underlying this selectivity are considered. Attention is given to special physical and chemical conditions that may cause structural defects in the bilayer organization and can affect the selective permeability properties of the bilayer or completely deteriorate its barrier function. Finally an evaluation is given of intrinsic ionophoretic activity in lipid bilayers containing negatively charged lipids.
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Affiliation(s)
- J de Gier
- Department of Biochemistry of Membranes, University of Utrecht, The Netherlands
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47
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Adelina P, Da Costa MM, Madeira VM. Liposomes from the thermophilic eubacterium Thermus SP. fluorescence polarization and permeability properties. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0020-711x(90)90242-u] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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48
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Davenport L, Knutson JR, Brand L. Fluorescence studies of membrane dynamics and heterogeneity. Subcell Biochem 1989; 14:145-88. [PMID: 2655193 DOI: 10.1007/978-1-4613-9362-7_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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49
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Yamauchi K, Yamamoto I, Kinoshita M. Surface charge modulation of liposomes by enzymatic hydrolysis of macrocyclic 1,2-dotriacontanedioyl-sn-glycero-3-phosphocholine. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 938:51-60. [PMID: 3337817 DOI: 10.1016/0005-2736(88)90121-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
1,2-Dotriacontanedioyl-sn-glycero-3-phosphocholine (dTPC) was synthesized, and by a sonication method, dTPC was transformed into liposomes with physical features (charge, size, gel-to-liquid crystalline phase transition constants, etc.) similar to those of liposomes made of acyclic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Quantitative enzymatic assays using phospholipases A2 and C showed that dTPC was comparable with or better than DPPC as a substrate. Remarkably, the liposomes assembled from a mixture of dTPC and 1,2-distearyl-sn-glycero-3-phosphocholine were converted rapidly into anionic liposomes at pH 7 by the action of phospholipase A2, keeping their vesicular structure and exposing CO2H groups of the lysolipids of dTPC on the membrane surface. The use of dTPC is discussed in conjunction with the enzyme-catalyzed modification of the liposomes.
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Affiliation(s)
- K Yamauchi
- Department of Applied Chemistry, Osaka City University, Japan
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50
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Boggs JM. Lipid intermolecular hydrogen bonding: influence on structural organization and membrane function. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 906:353-404. [PMID: 3307919 DOI: 10.1016/0304-4157(87)90017-7] [Citation(s) in RCA: 566] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The great variety of different lipids in membranes, with modifications to the hydrocarbon chains, polar groups and backbone structure suggests that many of these lipids may have unique roles in membrane structure and function. Acidic groups on lipids are clearly important, since they allow interaction with basic groups on proteins and with divalent cations. Another important property of certain lipids is their ability to interact intermolecularly with other lipids via hydrogen bonds. This interaction occurs through acidic and basic moieties in the polar head groups of phospholipids, and the amide moiety and hydroxyl groups on the acyl chain, sphingosine base and sugar groups of sphingo- and glycolipids. The putative ability of different classes of lipids to interact by intermolecular hydrogen bonding, the molecular groups which may participate and the effect of these interactions on some of their physical properties are summarized in Table IX. It is frequently questioned whether intermolecular hydrogen bonding could occur between lipids in the presence of water. Correlations of their properties with their molecular structures, however, suggest that it can. Participation in intermolecular hydrogen bonding increases the lipid phase transition temperature by approx. 8-16 Cdeg relative to the electrostatically shielded state and by 20-30 Cdeg relative to the repulsively charged state, while having variable effects on the enthalpy. It increases the packing density in monolayers, possibly also in the liquid-crystalline phase in bilayers, and decreases the lipid hydration. These effects can probably be accounted for by transient, fluctuating hydrogen bonds involving only a small percentage of the lipid at any one time. Thus, rotational and lateral diffusion of the lipids may take place but at a slower rate, and the lateral expansion is limited. Intermolecular hydrogen bonding between lipids in bilayers may be significantly stabilized, despite the presence of water, by the fact that the lipids are already intermolecularly associated as a result of the hydrophobic effect and the Van der Waals' interactions between their chains. The tendency of certain lipids to self-associate, their asymmetric distribution in SUVs, their preferential association with cholesterol in non-cocrystallizing mixtures, their temperature-induced transitions to the hexagonal phase and their inhibitory effect on penetration of hydrophobic residues of proteins partway into the bilayer can all be explained by their participation in intermolecular hydrogen bonding interactions.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J M Boggs
- Department of Biochemistry, Hospital for Sick Children, Toronto, Canada
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