1
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Gh. MS, Wilhelm MJ, Dai HL. Observing mechanosensitive channels in action in living bacteria. BIOPHYSICAL REPORTS 2024; 4:100141. [PMID: 38189030 PMCID: PMC10765490 DOI: 10.1016/j.bpr.2023.100141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/07/2023] [Indexed: 01/09/2024]
Abstract
Mechanosensitive (MS) channels act to protect the cytoplasmic membrane (CM) of living cells from environmental changes in osmolarity. In this report, we demonstrate the use of time-resolved second-harmonic light scattering (SHS) as a means of experimentally observing the relative state (open versus closed) of MS channels in living bacteria suspended in different buffer solutions. Specifically, the state of the MS channels was selectively controlled by changing the composition of the suspension medium, inducing either a transient or persistent osmotic shock. SHS was then used to monitor transport of the SHG-active cation, malachite green, across the bacterial CM. When MS channels were forced open, malachite green cations were able to cross the CM at a rate at least two orders of magnitude faster compared with when the MS channels were closed. These observations were corroborated using both numerical model simulations and complementary fluorescence experiments, in which the propensity for the CM impermeant cation, propidium, to stain cells was shown to be contingent upon the relative state of the MS channels (i.e., cells with open MS channels fluoresced red, cells with closed MS channels did not). Application of time-resolved SHS to experimentally distinguish MS channels opened via osmotic shock versus chemical activation, as well as a general comparison with the patch-clamp method is discussed.
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Affiliation(s)
| | | | - Hai-Lung Dai
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania
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2
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Blake MJ, Castillo HB, Curtis AE, Calhoun TR. Facilitating flip-flop: Structural tuning of molecule-membrane interactions in living bacteria. Biophys J 2023; 122:1735-1747. [PMID: 37041744 PMCID: PMC10209030 DOI: 10.1016/j.bpj.2023.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/17/2023] [Accepted: 04/04/2023] [Indexed: 04/13/2023] Open
Abstract
The first barrier that a small molecule must overcome before trespassing into a living cell is the lipid bilayer surrounding the intracellular content. It is imperative, therefore, to understand how the structure of a small molecule influences its fate in this region. Through the use of second harmonic generation, we show how the differing degrees of ionic headgroups, conjugated system, and branched hydrocarbon tail disparities of a series of four styryl dye molecules influence the propensity to "flip-flop" or to be further organized in the outer leaflet by the membrane. We show here that initial adsorption experiments match previous studies on model systems; however, more complex dynamics are observed over time. Aside from probe molecule structure, these dynamics also vary between cell species and can deviate from trends reported based on model membranes. Specifically, we show here that the membrane composition is an important factor to consider for headgroup-mediated small-molecule dynamics. Overall, the findings presented here on how structural variability of small molecules impacts their initial adsorption and eventual destinations within membranes in the context of living cells could have practical applications in antibiotic and drug adjuvant design.
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Affiliation(s)
- Marea J Blake
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee
| | - Hannah B Castillo
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee
| | - Anna E Curtis
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee
| | - Tessa R Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee.
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3
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Dupertuis N, Tarun OB, Lütgebaucks C, Roke S. Three-Dimensional Confinement of Water: H 2O Exhibits Long-Range (>50 nm) Structure while D 2O Does Not. NANO LETTERS 2022; 22:7394-7400. [PMID: 36067223 DOI: 10.1021/acs.nanolett.2c02206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Water is the liquid of life thanks to its three-dimensional adaptive hydrogen (H)-bond network. Confinement of this network may lead to dramatic structural changes influencing chemical and physical transformations. Although confinement effects occur on a <1 nm length scale, the upper length scale limit is unknown. Here, we investigate 3D-confinement over lengths scales ranging from 58-140 nm. By confining water in zwitterionic liposomes of different sizes and measuring the change in H-bond network conformation using second harmonic scattering (SHS), we determined long-range confinement effects in light and heavy water. D2O displays no detectable 3D-confinement effects <58 nm (<3 × 106 D2O molecules). H2O is distinctly different. The vesicle enclosed inner H-bond network has a different conformation compared to the outside network and the SHS response scales with the volume of the confining space. H2O displays confinement effects over distances >100 nm (>2 × 107 H2O molecules).
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Affiliation(s)
- Nathan Dupertuis
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Orly B Tarun
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Cornelis Lütgebaucks
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering (IMX), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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4
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Hou Y, Xu B, Chen SL, Gan W, Yuan Q, Lin X. Understanding the different cross-membrane transport kinetics of two charged molecules on the DOPG lipid surface with second harmonic generation and MD simulation. SOFT MATTER 2022; 18:4305-4314. [PMID: 35620962 DOI: 10.1039/d2sm00167e] [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
A clear physical picture of the dynamic behavior of molecules on the surface of the lipid membrane is highly desired and has attracted great attention from researchers. In this study, a step forward in this direction based on previous studies was presented with second harmonic generation (SHG) and molecular dynamic (MD) simulation. Specifically, details on the orientation flipping and cross-membrane transport of two charged molecules, 4-(4-diethylaminostyry)-1-methyl-pyridinium iodide (D289) and malachite green (MG), on the surface of 2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (DOPG) lipids were presented. Firstly, the orientation flipping of the two molecules on the surface of lipids before their cross-membrane transport was confirmed by the MD simulation. Then, the concentration dependent rate of the cross membrane transport for MG/D289 was analyzed. It was found that a simplified model could satisfactorily interpret the faster cross-membrane transport of MG under higher bulk concentrations. A different concentration dependent dynamics was observed with D289 and the reason behind it was also discussed. With this investigation, the surface structures and dynamics of D289 and MG on the DOPG lipid surface were clearly presented.
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Affiliation(s)
- Yi Hou
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Science, Harbin Institute of Technology (Shenzhen), University Town, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Shenzhen 518055, Guangdong, Harbin 150001, Heilongjiang, China.
| | - Baomei Xu
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Science, Harbin Institute of Technology (Shenzhen), University Town, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Shenzhen 518055, Guangdong, Harbin 150001, Heilongjiang, China.
| | - Shun-Li Chen
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Province, Shantou University, Shantou 515063, Guangdong, China
| | - Wei Gan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Science, Harbin Institute of Technology (Shenzhen), University Town, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Shenzhen 518055, Guangdong, Harbin 150001, Heilongjiang, China.
| | - Qunhui Yuan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong, China.
| | - Xi Lin
- School of Materials Science and Engineering, and Institute of Materials Genome & Big Data, Harbin Institute of Technology(Shenzhen), University Town, Shenzhen 518055, China.
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Li J, Chen SL, Hou Y, Yuan Q, Gan W. Revealing the mechanisms of vesicle formation with multiple spectral methods. Phys Chem Chem Phys 2022; 24:12465-12475. [PMID: 35575256 DOI: 10.1039/d2cp01183b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The investigation of the self-assembly of amphiphilic molecules and the formation of micelles/vesicles has attracted significant attention. However, in situ and real-time methods for such studies are rare. Here, a surface-sensitive second harmonic generation (SHG) technique was applied to study the formation of vesicles in solutions of an anti-cancer drug, doxorubicin (DOX), and a generally used surfactant (sodium bis (2-ethylhexyl) sulfosuccinate, AOT). With the aid of two-photon fluorescence (TPF), Rayleigh scattering and TEM, we revealed the structural evolution of the aggregated micelles/vesicles. It was found that AOT and DOX molecules rapidly aggregated and formed micelles in the solution. The residual DOX then acted as a "glue" that induced the aggregating/growing of the micelles and the transformation from aggregates to vesicles. The existence of lipid films, which was considered as the necessary intermediate state for vesicle formation, was excluded via the SHG observations, indicating that hollow shells may be directly transformed from solid aggregated micelles in the self-assembly formation of complex vesicles. The combined spectroscopic methods were also used to investigate the formation of vesicles from a commonly used lipid (i.e., 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt, DOPG) from its stacked bilayers. The swelling, curving and sealing of the DOPG bilayers for vesicle formation was monitored and clear dynamics were revealed. This work shows that the vesicle formation mechanism varies with the initial state of the surfactant/lipid molecules. It not only demonstrates the capability of the combined spectroscopic methods in investigating the aggregated systems but also provides new insight for understanding the formation of vesicles.
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Affiliation(s)
- Jianhui Li
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, also School of Science, Harbin Institute of Technology (Shenzhen), University Town, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Shenzhen 518055, Guangdong, Harbin 150001, Heilongjiang, China.
| | - Shun-Li Chen
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Province, Shantou University, Shantou 515063, Guangdong, China
| | - Yi Hou
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, also School of Science, Harbin Institute of Technology (Shenzhen), University Town, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Shenzhen 518055, Guangdong, Harbin 150001, Heilongjiang, China.
| | - Qunhui Yuan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, also School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong, China
| | - Wei Gan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, also School of Science, Harbin Institute of Technology (Shenzhen), University Town, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Shenzhen 518055, Guangdong, Harbin 150001, Heilongjiang, China.
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6
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Miller LN, Blake MJ, Page EF, Castillo HB, Calhoun TR. Phosphate Ions Alter the Binding of Daptomycin to Living Bacterial Cell Surfaces. ACS Infect Dis 2021; 7:3088-3095. [PMID: 34605244 DOI: 10.1021/acsinfecdis.1c00397] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Advancements in antibiotic drug design are often hindered by missing information on how these small molecules interact with living cells. The antibiotic, daptomycin, has found clinical success and an emerging resistance, but a comprehensive picture of its mechanism of action has remained elusive. Using a surface-specific spectroscopy technique, second harmonic generation, we are able to quantitatively assess the binding of daptomycin to living cell membranes without the addition of exogenous labels. Our results reveal similar binding affinities for both Gram-positive and Gram-negative bacteria studied, including Escherichia coli. More importantly, we show that the presence of phosphate ions influences the binding of daptomycin to the Gram-positive bacterium Enterococcus faecalis. The role of environmental phosphate has not previously been considered in any proposed mechanism, and its implications are expected to be important in vivo.
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Affiliation(s)
- Lindsey N. Miller
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Marea J. Blake
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Eleanor F. Page
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Hannah B. Castillo
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Tessa R. Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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7
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Li B, Li J, Gan W, Tan Y, Yuan Q. Unveiling the Molecular Dynamics in a Living Cell to the Subcellular Organelle Level Using Second-Harmonic Generation Spectroscopy and Microscopy. Anal Chem 2021; 93:14146-14152. [PMID: 34648265 DOI: 10.1021/acs.analchem.1c02604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Second-harmonic generation (SHG) microscopy has been proved to be a powerful method for investigating the structures of biomaterials. SHG spectra were also generally used to probe the adsorption and cross-membrane transport of molecules on lipid bilayers in situ and in real time. In this work, we applied SHG and two-photon fluorescence (TPF) spectra to investigate the dynamics of an amphiphilic ion with an SHG and TPF chromophore, D289 (4-(4-diethylaminostyry)-1-methyl-pyridinium iodide), on the surface of human chronic myelogenous leukemia (K562) cells and the subcellular structures inside the cells. The adsorption and cross-membrane transport of D289 into the cells and then into the organelles such as mitochondria were revealed. SHG images were also recorded and used to demonstrate their capability of probing molecular dynamics in organelles in K562 cells. This work demonstrated the first SHG investigation of the cross-membrane transport dynamics on the surface of subcellular organelles. It may also shed light on the differentiation of different types of subcellular structures in cells.
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Affiliation(s)
- Bifei Li
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Also School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong; School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China
| | - Jianhui Li
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Also School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong; School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China
| | - Wei Gan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Also School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong; School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China
| | - Ying Tan
- State Key Laboratory of Chemical Oncogenomics, Key Laboratory of Chemical Biology, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong 518055, China
| | - Qunhui Yuan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Also School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong, China
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8
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Hamal P, Subasinghege Don V, Nguyenhuu H, Ranasinghe JC, Nauman JA, McCarley RL, Kumar R, Haber LH. Influence of Temperature on Molecular Adsorption and Transport at Liposome Surfaces Studied by Molecular Dynamics Simulations and Second Harmonic Generation Spectroscopy. J Phys Chem B 2021; 125:10506-10513. [PMID: 34495664 PMCID: PMC8474114 DOI: 10.1021/acs.jpcb.1c04263] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A fundamental understanding of the kinetics and thermodynamics of chemical interactions at the phospholipid bilayer interface is crucial for developing potential drug-delivery applications. Here we use molecular dynamics (MD) simulations and surface-sensitive second harmonic generation (SHG) spectroscopy to study the molecular adsorption and transport of a small organic cation, malachite green (MG), at the surface of 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DOPG) liposomes in water at different temperatures. The temperature-dependent adsorption isotherms, obtained by SHG measurements, provide information on adsorbate concentration, free energy of adsorption, and associated changes in enthalpy and entropy, showing that the adsorption process is exothermic, resulting in increased overall entropy. Additionally, the molecular transport kinetics are found to be more rapid under higher temperatures. Corresponding MD simulations are used to calculate the free energy profiles of the adsorption and the molecular orientation distributions of MG at different temperatures, showing excellent agreement with the experimental results.
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Affiliation(s)
- Prakash Hamal
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States
| | - Visal Subasinghege Don
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States
| | - Huy Nguyenhuu
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States
| | - Jeewan C Ranasinghe
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States
| | - Julia A Nauman
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States
| | - Robin L McCarley
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States
| | - Revati Kumar
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States
| | - Louis H Haber
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, United States
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9
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Sharifian Gh M. Recent Experimental Developments in Studying Passive Membrane Transport of Drug Molecules. Mol Pharm 2021; 18:2122-2141. [PMID: 33914545 DOI: 10.1021/acs.molpharmaceut.1c00009] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ability to measure the passive membrane permeation of drug-like molecules is of fundamental biological and pharmaceutical importance. Of significance, passive diffusion across the cellular membranes plays an effective role in the delivery of many pharmaceutical agents to intracellular targets. Hence, approaches for quantitative measurement of membrane permeability have been the topics of research for decades, resulting in sophisticated biomimetic systems coupled with advanced techniques. In this review, recent developments in experimental approaches along with theoretical models for quantitative and real-time analysis of membrane transport of drug-like molecules through mimetic and living cell membranes are discussed. The focus is on time-resolved fluorescence-based, surface plasmon resonance, and second-harmonic light scattering approaches. The current understanding of how properties of the membrane and permeant affect the permeation process is discussed.
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Affiliation(s)
- Mohammad Sharifian Gh
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, United States
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10
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Wilhelm MJ, Sharifian Gh M, Wu T, Li Y, Chang CM, Ma J, Dai HL. Determination of bacterial surface charge density via saturation of adsorbed ions. Biophys J 2021; 120:2461-2470. [PMID: 33932437 DOI: 10.1016/j.bpj.2021.04.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 01/17/2023] Open
Abstract
Bacterial surface charge is a critical characteristic of the cell's interfacial physiology that influences how the cell interacts with the local environment. A direct, sensitive, and accurate experimental technique capable of quantifying bacterial surface charge is needed to better understand molecular adaptations in interfacial physiology in response to environmental changes. We introduce here the method of second-harmonic light scattering (SHS), which is capable of detecting the number of molecular ions adsorbed as counter charges on the exterior bacterial surface, thereby providing a measure of the surface charge. In this first demonstration, we detect the small molecular cation, malachite green, electrostatically adsorbed on the surface of representative strains of Gram-positive and Gram-negative bacteria. Surprisingly, the SHS-deduced molecular transport rates through the different cellular ultrastructures are revealed to be nearly identical. However, the adsorption saturation densities on the exterior surfaces of the two bacteria were shown to be characteristically distinct. The negative charge density of the lipopolysaccharide coated outer surface of Gram-negative Escherichia coli (6.6 ± 1.3 nm-2) was deduced to be seven times larger than that of the protein surface layer of Gram-positive Lactobacillus rhamnosus (1.0 ± 0.2 nm-2). The feasibility of SHS-deduced bacterial surface charge density for Gram-type differentiation is presented.
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Affiliation(s)
- Michael J Wilhelm
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania.
| | | | - Tong Wu
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania
| | - Yujie Li
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania
| | - Chia-Mei Chang
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania
| | - Jianqiang Ma
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania
| | - Hai-Lung Dai
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania
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Hou Y, Li J, Liu X, Ruan Y, Chen SL, Yuan Q, Gan W. The effect of side group on the dynamic behavior of anthracyclines on DOPG lipid membranes revealed by second harmonic generation and fluorescence. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2020.111036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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12
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Wilhelm MJ, Dai HL. Molecule-Membrane Interactions in Biological Cells Studied with Second Harmonic Light Scattering. Chem Asian J 2019; 15:200-213. [PMID: 31721448 DOI: 10.1002/asia.201901406] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/12/2019] [Indexed: 12/13/2022]
Abstract
The nonlinear optical phenomenon second harmonic light scattering (SHS) can be used for detecting molecules at the membrane surfaces of living biological cells. Over the last decade, SHS has been developed for quantitatively monitoring the adsorption and transport of small and medium size molecules (both neutral and ionic) across membranes in living cells. SHS can be operated with both time and spatial resolution and is even capable of isolating molecule-membrane interactions at specific membrane surfaces in multi-membrane cells, such as bacteria. In this review, we discuss select examples from our lab employing time-resolved SHS to study real-time molecular interactions at the plasma membranes of biological cells. We first demonstrate the utility of this method for determining the transport rates at each membrane/interface in a Gram-negative bacterial cell. Next, we show how SHS can be used to characterize the molecular mechanism of the century old Gram stain protocol for classifying bacteria. Additionally, we examine how membrane structures and molecular charge and polarity affect adsorption and transport, as well as how antimicrobial compounds alter bacteria membrane permeability. Finally, we discuss adaptation of SHS as an imaging modality to quantify molecular adsorption and transport in sub-cellular regions of individual living cells.
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Affiliation(s)
- Michael J Wilhelm
- Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, PA 19122, USA
| | - Hai-Lung Dai
- Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, PA 19122, USA
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13
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Miller LN, Brewer WT, Williams JD, Fozo EM, Calhoun TR. Second Harmonic Generation Spectroscopy of Membrane Probe Dynamics in Gram-Positive Bacteria. Biophys J 2019; 117:1419-1428. [PMID: 31586521 DOI: 10.1016/j.bpj.2019.09.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 09/11/2019] [Accepted: 09/13/2019] [Indexed: 11/17/2022] Open
Abstract
Bacterial membranes are complex mixtures with dispersity that is dynamic over scales of both space and time. To capture adsorption onto and transport within these mixtures, we conduct simultaneous second harmonic generation (SHG) and two-photon fluorescence measurements on two different gram-positive bacterial species as the cells uptake membrane-specific probe molecules. Our results show that SHG not only can monitor the movement of small molecules across membrane leaflets but also is sensitive to higher-level ordering of the molecules within the membrane. Further, we show that the membranes of Staphylococcus aureus remain more dynamic after longer times at room temperature in comparison to Enterococcus faecalis. Our findings provide insight into the variability of activities seen between structurally similar molecules in gram-positive bacteria while also demonstrating the power of SHG to examine these dynamics.
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Affiliation(s)
- Lindsey N Miller
- Department of Chemistry, University of Tennesseee, Knoxville, Tennessee
| | - William T Brewer
- Department of Microbiology, University of Tennesseee, Knoxville, Tennessee
| | - Julia D Williams
- Department of Microbiology, University of Tennesseee, Knoxville, Tennessee
| | - Elizabeth M Fozo
- Department of Microbiology, University of Tennesseee, Knoxville, Tennessee
| | - Tessa R Calhoun
- Department of Chemistry, University of Tennesseee, Knoxville, Tennessee.
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14
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Hamal P, Nguyenhuu H, Subasinghege Don V, Kumal RR, Kumar R, McCarley RL, Haber LH. Molecular Adsorption and Transport at Liposome Surfaces Studied by Molecular Dynamics Simulations and Second Harmonic Generation Spectroscopy. J Phys Chem B 2019; 123:7722-7730. [PMID: 31407578 DOI: 10.1021/acs.jpcb.9b05954] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A fundamental understanding of the factors that determine the interactions with and transport of small molecules through phospholipid membranes is crucial in developing liposome-based drug delivery systems. Here we combine time-dependent second harmonic generation (SHG) measurements with molecular dynamics simulations to elucidate the events associated with adsorption and transport of the small molecular cation, malachite green isothiocyanate (MGITC), in colloidal liposomes of different compositions. The molecular transport of MGITC through the liposome bilayer is found to be more rapid in 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) and 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPG and DOPS, respectively) liposomes, while the molecular transport is slower in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes. Interestingly, MGITC is observed to neither adsorb nor transport in trimethyl quinone-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (QPADOPE) liposomes due to shielding by the quinone group. The modified Langmuir adsorption isotherm model is used to determine the free energy of adsorption for MGITC, which is found to be less negative in DOPC than in DOPG and DOPS, caused by lower electrostatic interactions between the positively charged dye and the zwitterionic DOPC liposome surface. The results are compared to our previous investigations, which showed that malachite green (MG) adsorbs and transports in DOPG and DOPS liposomes but not in DOPC and QPADOPE liposomes. Molecular dynamics simulations are used to investigate the adsorption and transport properties of MG and MGITC in DOPC and DOPG liposomes using umbrella sampling to determine the free energy profiles and interfacial molecular orientations. Together, these time-resolved SHG studies and corresponding molecular dynamics simulations characterize the complicated chemical interactions at different lipid membranes to provide key molecular-level insights for potential drug delivery applications. The results also point toward understanding the role of chemical functional groups, in this case isothiocyanate, in controlling molecular adsorption at and transport through lipid bilayers.
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Affiliation(s)
- Prakash Hamal
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803-1804 , United States
| | - Huy Nguyenhuu
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803-1804 , United States
| | - Visal Subasinghege Don
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803-1804 , United States
| | - Raju R Kumal
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803-1804 , United States
| | - Revati Kumar
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803-1804 , United States
| | - Robin L McCarley
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803-1804 , United States
| | - Louis H Haber
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803-1804 , United States
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15
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Gayen A, Kumar D, Matheshwaran S, Chandra M. Unveiling the Modulating Role of Extracellular pH in Permeation and Accumulation of Small Molecules in Subcellular Compartments of Gram-negative Escherichia coli using Nonlinear Spectroscopy. Anal Chem 2019; 91:7662-7671. [PMID: 30986344 DOI: 10.1021/acs.analchem.9b00574] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Quantitative evaluation of small molecule permeation and accumulation in Gram-negative bacteria is important for drug development against these bacteria. While these measurements are commonly performed at physiological pH, Escherichia coli and many other Enterobacteriaceae infect human gastrointestinal and urinary tracts, where they encounter different pH conditions. To understand how external pH affects permeation and accumulation of small molecules in E. coli cells, we apply second harmonic generation (SHG) spectroscopy using SHG-active antimicrobial compound malachite green as the probe molecule. Using SHG, we quantify periplasmic and cytoplasmic accumulations separately in live E. coli cells, which was never done before. Compartment-wise measurements reveal accumulation of the probe molecule in cytoplasm at physiological and alkaline pH, while entrapment in periplasm at weakly acidic pH and retention in external solution at highly acidic pH. Behind such disparity in localizations, up to 2 orders of magnitude reduction in permeability across the inner membrane at weakly acidic pH and outer membrane at highly acidic pH are found to play key roles. Our results unequivocally demonstrate the control of external pH over entry and compartment-wise distribution of small molecules in E. coli cells, which is a vital information and should be taken into account in antibiotic screening against E. coli and other Enterobacteriaceae members. In addition, our results demonstrate the ability of malachite green as an excellent SHG-indicator of changes of individual cell membrane and periplasm properties of live E. coli cells in response to external pH change from acidic to alkaline. This finding, too, has great importance, as there is barely any other molecular probe that can provide similar information.
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16
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Hou Y, Chen SL, Gan W, Ma X, Yuan Q. Understanding the Dynamic Behavior of an Anticancer Drug, Doxorubicin, on a Lipid Membrane Using Multiple Spectroscopic Techniques. J Phys Chem B 2019; 123:3756-3762. [PMID: 30983340 DOI: 10.1021/acs.jpcb.9b01941] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The interaction, including the adsorption and embedding, of a widely applied anticancer drug, doxorubicin, with a lipid membrane was investigated. Second harmonic generation and two photon fluorescence were used as a powerful combination capable in revealing this dynamic process at the interface. The adsorption, association, deassociation and embedding of doxorubicin on the lipid membrane were clearly identified based on the consistency in the dynamic parameters revealed by the time dependent second harmonic generation and two-photon fluorescence measurements. This work also presents a new approach for in situ measurement of the adsorption density of doxorubicin on lipid membrane, benefiting from the two-photon fluorescence signal of doxorubicin being significantly altered by its chemical environment. The analysis of the location and molecular density based on the fluorescent efficiency of the chromophores makes the fluorescence measurement a "surface sensitive" technique as well. The analytical procedures used in this work are expected to aid in understanding the interaction between fluorescent molecules and lipid membranes in general.
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Affiliation(s)
- Yi Hou
- State Key Laboratory of Advanced Welding and Joining, and School of Science , Harbin Institute of Technology (Shenzhen) , University Town, Shenzhen 518055 , Guangdong China
| | - Shun-Li Chen
- State Key Laboratory of Advanced Welding and Joining, and School of Science , Harbin Institute of Technology (Shenzhen) , University Town, Shenzhen 518055 , Guangdong China
| | - Wei Gan
- State Key Laboratory of Advanced Welding and Joining, and School of Science , Harbin Institute of Technology (Shenzhen) , University Town, Shenzhen 518055 , Guangdong China
| | - Xing Ma
- State Key Laboratory of Advanced Welding and Joining, and School of Materials Science and Engineering , Harbin Institute of Technology (Shenzhen) , University Town, Shenzhen 518055 , Guangdong China
| | - Qunhui Yuan
- State Key Laboratory of Advanced Welding and Joining, and School of Materials Science and Engineering , Harbin Institute of Technology (Shenzhen) , University Town, Shenzhen 518055 , Guangdong China
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17
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Sharifian Gh M, Wilhelm MJ, Moore M, Dai HL. Spatially Resolved Membrane Transport in a Single Cell Imaged by Second Harmonic Light Scattering. Biochemistry 2019; 58:1841-1844. [PMID: 30912648 DOI: 10.1021/acs.biochem.9b00110] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We demonstrate that time-resolved second harmonic (SH) light scattering, when applied as an imaging modality, can be used to spatially resolve the adsorption and transport rates of molecules diffusing across the membrane in a living cell. As a representative example, we measure the passive transport of the amphiphilic ion, malachite green, across the plasma membrane in living human dermal fibroblast cells. Analysis of the time-resolved SH images reveals that membrane regions, which appear to be enduring higher stress, exhibit slower transport rates. It is proposed that this stress-transport relation may be a result of local enrichment of membrane rigidifiers as part of a response to maintain membrane integrity under strain.
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Affiliation(s)
- Mohammad Sharifian Gh
- Department of Chemistry , Temple University , 1901 N. 13th Street , Philadelphia , Pennsylvania 19122 , United States
| | - Michael J Wilhelm
- Department of Chemistry , Temple University , 1901 N. 13th Street , Philadelphia , Pennsylvania 19122 , United States
| | - Michael Moore
- Optical Science Center for Applied Research , Delaware State University , Dover , Delaware 19904 , United States
| | - Hai-Lung Dai
- Department of Chemistry , Temple University , 1901 N. 13th Street , Philadelphia , Pennsylvania 19122 , United States
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18
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Wilhelm MJ, Sharifian Gh M, Dai HL. Influence of molecular structure on passive membrane transport: A case study by second harmonic light scattering. J Chem Phys 2019; 150:104705. [PMID: 30876365 DOI: 10.1063/1.5081720] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present an experimental study, using the surface sensitive technique, second harmonic light scattering (SHS), to examine the influence of structure on the propensity of a molecule to passively diffuse across a phospholipid membrane. Specifically, we monitor the relative tendency of the structurally similar amphiphilic cationic dyes, malachite green (MG) and crystal violet (CV), to transport across membranes in living cells (E. coli) and biomimetic liposomes. Despite having nearly identical molecular structures, molecular weights, cationic charges, and functional groups, MG is of lower overall symmetry and consequently has a symmetry allowed permanent dipole moment, which CV does not. The two molecules showed drastically different interactions with phospholipid membranes. MG is observed to readily cross the hydrophobic interior of the bacterial cytoplasmic membrane. Conversely, CV does not. Furthermore, experiments conducted with biomimetic liposomes, constructed from the total lipid extract of E. coli and containing no proteins, show that while MG is able to diffuse across the liposome membrane, CV does not. These observations indicate that the SHS results measured with bacteria do not result from the functions of efflux pumps, but suggests that MG possesses an innate molecular property (which is absent in CV) that allows it to passively diffuse across the hydrophobic interior of a phospholipid membrane.
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Affiliation(s)
- Michael J Wilhelm
- Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, USA
| | - Mohammad Sharifian Gh
- Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, USA
| | - Hai-Lung Dai
- Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, USA
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19
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Sharifian Gh. M, Wilhelm MJ, Dai HL. Azithromycin-Induced Changes to Bacterial Membrane Properties Monitored in Vitro by Second-Harmonic Light Scattering. ACS Med Chem Lett 2018; 9:569-574. [PMID: 29937984 DOI: 10.1021/acsmedchemlett.7b00499] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/09/2018] [Indexed: 01/15/2023] Open
Abstract
We present a nonlinear light scattering method for monitoring, with real-time resolution and membrane specificity, changes in molecular adsorption, and transport at bacterial membranes induced by an antimicrobial compound. Specifically, time-resolved second-harmonic light scattering (SHS) is used to quantify azithromycin-induced changes to bacterial membrane permeability in colloidal suspensions of living Escherichia coli. Variations in membrane properties are monitored through changes in the adsorption and transport rates of malachite green, a hydrophobic cation that gives SHS signal. Regardless of concentration, instantaneous treatment with azithromycin showed no significant changes in membrane permeability. However, 1 h pretreatment with subminimum inhibitory concentrations of azithromycin induced an order-of-magnitude enhancement in the permeability of both the outer membrane and, through facilitation of a new transport mechanism, the cytoplasmic membrane of the bacteria as well. This study illustrates SHS as a novel tool for monitoring antimicrobial-induced changes to membrane properties in living bacteria.
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Affiliation(s)
- Mohammad Sharifian Gh.
- Department of Chemistry, Temple University
, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Michael J. Wilhelm
- Department of Chemistry, Temple University
, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Hai-Lung Dai
- Department of Chemistry, Temple University
, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
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20
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Kim JH. Two-step adsorption kinetics of malachite green on anionic polystyrene microspheres in aqueous solution probed by second harmonic generation. Phys Chem Chem Phys 2017; 19:21887-21892. [PMID: 28787062 DOI: 10.1039/c7cp03088f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Adsorption of organic cations of malachite green (MG) on an anionic microsphere surface was monitored in real time using a surface-specific second-harmonic generation (SHG) technique. This adsorption was found to consist of two processes of different timescales for all MG concentrations, which has not been considered in previous SHG experiments. The two-step adsorption can be well explained by our suggested model, which consists of an initial fast electrostatic alignment of weakly bound MG followed by slow non-electrostatic adsorption of MG on the surface of a microsphere. This study shows the importance of kinetics measurements in providing full understanding of adsorption of charged molecules on colloid surfaces.
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Affiliation(s)
- Joon Heon Kim
- Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.
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21
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Sharifian Gh M, Wilhelm MJ, Dai HL. Label-Free Optical Method for Quantifying Molecular Transport Across Cellular Membranes In Vitro. J Phys Chem Lett 2016; 7:3406-3411. [PMID: 27518496 DOI: 10.1021/acs.jpclett.6b01483] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate a nonlinear optical method for the label-free quantification of membrane transport rates of small/medium size molecules in living cells. Specifically, second-harmonic generation (SHG) laser scattering permits surface-specific characterization of transport across membranes. Unfortunately, most biologically relevant molecules are SHG-inactive. In the interest of extending this methodology for characterizing transport of any molecule, we monitor the SHG produced from an SHG-active reference molecule, in the presence of an SHG-inactive target molecule-of-interest as both molecules compete to cross a membrane. Of significance, the SHG-inactive target transport rate can be deduced as a perturbation in the measured transport rate of the reference. As proof-of-principle, we examine competitive transport of the strongly SHG-active cation, malachite green (MG), in the presence of a weakly SHG-active dication, propidium (Pro), across the outer-membrane protein channels in living bacteria. Comparison of the extracted and directly measured Pro transport rates validates the effectiveness of the method.
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Affiliation(s)
- Mohammad Sharifian Gh
- Department of Chemistry, Temple University , 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Michael J Wilhelm
- Department of Chemistry, Temple University , 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Hai-Lung Dai
- Department of Chemistry, Temple University , 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
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22
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Quantitative parameters of complexes of tris(1-alkylindol-3-yl)methylium salts with serum albumin: Relevance for the design of drug candidates. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2016; 162:570-576. [PMID: 27475780 DOI: 10.1016/j.jphotobiol.2016.07.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/16/2016] [Indexed: 01/12/2023]
Abstract
Triarylmethane derivatives are extensively investigated as antitumor and antibacterial drug candidates alone and as photoactivatable compounds. In the series of tris(1-alkylindol-3-yl)methylium salts (TIMs) these two activities differed depending on the length of N-alkyl chain, with C4-5 derivatives being the most potent compared to the shorter or longer chain analogs and to the natural compound turbomycin A (no N-substituent). Given that the human serum albumin (HSA) is a major transporter protein with which TIMs can form stable complexes, and that the formation of these complexes might be advantageous for phototoxicity of TIMs we determined the quantitative parameters of TIMs-HSA binding using spectroscopic methods and molecular docking. TIMs bound to HSA (1:1 stoichiometry) altered the protein's secondary structure by changing the α-helix/β-turn ratio. The IIa subdomain (Sudlow site I) is the preferred TIM binding site in HSA as determined in competition experiments with reference drugs ibuprofen and warfarin. The values of binding constants increased with the number of CH2 groups from 0 to 6 and then dropped down for C10 compound, a dependence similar to the one observed for cytocidal potency of TIMs. We tend to attribute this non-linear dependence to an interplay between hydrophobicity and steric hindrance, the two key characteristics of TIMs-HSA complexes calculated in the molecular docking procedure. These structure-activity relationships provide evidence for rational design of TIMs-based antitumor and antimicrobial drugs.
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23
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Wilhelm MJ, Sheffield JB, Sharifian Gh. M, Wu Y, Spahr C, Gonella G, Xu B, Dai HL. Gram's Stain Does Not Cross the Bacterial Cytoplasmic Membrane. ACS Chem Biol 2015; 10:1711-7. [PMID: 25879387 DOI: 10.1021/acschembio.5b00042] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
For well over a century, Hans Christian Gram's famous staining protocol has been the standard go-to diagnostic for characterizing unknown bacteria. Despite continuous and ubiquitous use, we now demonstrate that the current understanding of the molecular mechanism for this differential stain is largely incorrect. Using the fully complementary time-resolved methods: second-harmonic light-scattering and bright-field transmission microscopy, we present a real-time and membrane specific quantitative characterization of the bacterial uptake of crystal-violet (CV), the dye used in Gram's protocol. Our observations contradict the currently accepted mechanism which depicts that, for both Gram-negative and Gram-positive bacteria, CV readily traverses the peptidoglycan mesh (PM) and cytoplasmic membrane (CM) before equilibrating within the cytosol. We find that not only is CV unable to traverse the CM but, on the time-scale of the Gram-stain procedure, CV is kinetically trapped within the PM. Our results indicate that CV, rather than dyes which rapidly traverse the PM, is uniquely suited as the Gram stain.
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Affiliation(s)
- Michael J. Wilhelm
- Department
of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Joel B. Sheffield
- Department
of Biology, Temple University, 1900 N. 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - Mohammad Sharifian Gh.
- Department
of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Yajing Wu
- Department
of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Christian Spahr
- Department
of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Grazia Gonella
- Department
of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Bolei Xu
- Department
of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Hai-Lung Dai
- Department
of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, United States
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24
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Wilhelm MJ, Sharifian Gh M, Dai HL. Chemically Induced Changes to Membrane Permeability in Living Cells Probed with Nonlinear Light Scattering. Biochemistry 2015; 54:4427-30. [PMID: 26122620 DOI: 10.1021/acs.biochem.5b00600] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Second-harmonic light scattering (SHS) permits characterization of membrane-specific molecular transport in living cells. Herein, we demonstrate the use of time-resolved SHS for quantifying chemically induced enhancements in membrane permeability. As proof of concept, we examine the enhanced permeability of the cytoplasmic membrane in living Escherichia coli following addition of extracellular adenosine triphosphate (ATPe). The transport rate of the hydrophobic cation, malachite green, increases nearly an order of magnitude following addition of 0.1 mM ATPe. The absence of an ATPe-enhanced permeability in liposomes strongly suggests the induced effect is protein-mediated. The utility of SHS for elucidating the mechanism of action of antimicrobials is discussed.
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Affiliation(s)
- Michael J Wilhelm
- Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Mohammad Sharifian Gh
- Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Hai-Lung Dai
- Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
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