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Camp T, Mehta K, Sligar SG, Zhang K. Molecular Orientation Determination in Nanodiscs at the Single-Molecule Level. Anal Chem 2020; 92:2229-2236. [PMID: 31851490 DOI: 10.1021/acs.analchem.9b04950] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The function of membrane-bound proteins often depends on their interactions with the lipid bilayer. Bulk absorption-based linear dichroism has been historically used to investigate molecular orientations in the phospholipid bilayer but cannot resolve the actual distribution of molecules embedded in the membrane and is often limited by a poor signal-to-noise ratio. Here, we present single-molecule orientation determination by fluorescence-detected linear dichroism visualization in Nanodisc grids or SOLVING, to determine the molecular orientation of molecules assembled into nanoscale lipid bilayers. We provide a proof-of-concept by using SOLVING to quantitate the orientation distribution of two commonly used fluorescent dyes, DiO and BODIPY, in 10 nm Nanodiscs. Besides confirming the mean orientation determined by bulk absorption measurement, SOLVING provides the actual distribution of orientations and promises to provide key molecular insights into the topology and interactions of multiprotein complexes, such as those observed in intracellular signal transduction.
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Affiliation(s)
- Tyler Camp
- Center for Biophysics and Quantitative Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Kritika Mehta
- Department of Biochemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Stephen G Sligar
- Department of Biochemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Center for Biophysics and Quantitative Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Kai Zhang
- Department of Biochemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Center for Biophysics and Quantitative Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Neuroscience Program , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Beckman Institute , University of Illinois at Urbana-Champaign 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
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Alekseeva AS, Tretiakova DS, Melnikova DN, Molotkovsky UG, Boldyrev IA. Novel fluorescent membrane probe 2,3;5,6-bis(cyclohexyl)-BODIPY-labeled phosphatidylcholine. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2016. [DOI: 10.1134/s1068162016030031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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DeWitt BN, Dunn RC. Interaction of cholesterol in ternary lipid mixtures investigated using single-molecule fluorescence. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:995-1004. [PMID: 25531175 DOI: 10.1021/la503797w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fluorescence measurements of the sterol analog 23-(dipyrrometheneboron difluoride)-24-norcholesterol (BODIPY-cholesterol) are used to compare the effects of cholesterol (Chol) in monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC)/1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/Chol and chicken egg sphingomyelin (SM)/DOPC/Chol. Monolayers are formed using the Langmuir-Blodgett technique and compared at surface pressures of 8 and 30 mN/m. In particular, these ternary lipid mixtures are compared using both ensemble and single-molecule fluorescence measurements of BODIPY-cholesterol. In mixed monolayers incorporating 0.10 mol % BODIPY-cholesterol, fluorescence microscopy measurements as a function of cholesterol added reveal similar trends in monolayer phase structure for both DPPC/DOPC/Chol and SM/DOPC/Chol films. With a probe concentration reduced to ∼10(-8) mol % BODIPY-cholesterol, single-molecule fluorescence measurements using defocused polarized total internal reflection microscopy are used to characterize the orientations of BODIPY-cholesterol in the monolayers. Population histograms of the BODIPY emission dipole tilt angle away from the membrane normal reveal distinct insertion geometries with a preferred angle observed near 78°. The measured angles and populations are relatively insensitive to added cholesterol and changes in surface pressure for monolayers of SM/DOPC/Chol. For monolayers of DPPC/DOPC/Chol, however, the single-molecule measurements reveal significant changes in the BODIPY-cholesterol insertion geometry when the surface pressure is increased to 30 mN/m. These changes are discussed in terms of a squeeze-out mechanism for BODIPY-cholesterol in these monolayers and provide insight into the partitioning and arrangement of BODIPY-cholesterol in ternary lipid mixtures.
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Affiliation(s)
- Brittany N DeWitt
- Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas , 2030 Becker Drive, Lawrence, Kansas 66047, United States
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4
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Affiliation(s)
- Lydia Kisley
- Department of Chemistry and Department of Electrical and Computer
Engineering,
Rice Quantum Institute, Rice University, 6100 Main Street, MS-60, Houston, Texas 77005, United States
| | - Christy F. Landes
- Department of Chemistry and Department of Electrical and Computer
Engineering,
Rice Quantum Institute, Rice University, 6100 Main Street, MS-60, Houston, Texas 77005, United States
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6
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Armendariz KP, Dunn RC. Ganglioside influence on phospholipid films investigated with single molecule fluorescence measurements. J Phys Chem B 2013; 117:7959-66. [PMID: 23745772 DOI: 10.1021/jp405312a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Single molecule fluorescence measurements are used to probe the effects of GM1 in DPPC monolayers. Langmuir-Blodgett films of GM1 and DPPC were doped with ~10(-8) mol % of the fluorescent lipid probe, BODIPY-PC, and transferred onto glass substrates at 23 mN/m. As shown previously, the individual orientation of each BODIPY-PC probe in the membrane can be measured using defocused polarized total internal reflection fluorescence microscopy, revealing changes in film properties at the molecular level. Here, BODIPY-PC tilt angle histograms are used to characterize the effects of GM1 in DPPC films from 0.05 to 100 mol % GM1. At high GM1 levels (>5 mol % GM1), trends in the single molecule measurements agree with previous bulk measurements showing the turnover from condensing to expanding influence of GM1 at 15-20 mol %, thus validating the single molecule approach. At biologically relevant, low concentrations of GM1 (<5 mol % GM1), where bulk fluorescence measurements are less informative, the single molecule measurements reveal a marked influence of GM1 on film properties. The addition of trace amounts of GM1 to DPPC films leads to an expansion of the film which continues to 0.10 mol % GM1, above which the trend reverses and the condensing effect previously noted is observed.
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Affiliation(s)
- Kevin P Armendariz
- Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, 2030 Becker Drive, Lawrence, Kansas 66047, USA
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7
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Nelson N, Walder R, Schwartz DK. Single molecule dynamics on hydrophobic self-assembled monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:12108-13. [PMID: 22876990 DOI: 10.1021/la302369v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The interactions between adsorbate molecules and hydrophobic surfaces are of significant interest due to their importance in a variety of biological and separation processes. However, it is challenging to extrapolate macroscopic ensemble-averaged force measurements to molecular-level phenomena. Using total internal reflection fluorescence microscopy to image individual molecules at hydrophobic solid-aqueous interfaces, we directly observed dynamic behavior associated with the interactions between fluorescently labeled dodecanoic acid (our probe molecules) and self-assembled monolayers (SAM) comprising n-alkyltriethoxysilanes with systematically increasing chain length (from n = 4-18). In all cases, we observed at least two characteristic surface residence times and two diffusive modes, suggesting the presence of multiple distinct adsorbed populations. In general, the mean surface residence time increased and the mobility decreased with increasing SAM chain length, consistent with stronger probe-surface interactions. However, these trends were not primarily due to changes in characteristic residence times or diffusion coefficients associated with the individual populations but rather to a dramatic increase in the fraction associated with the long-lived slow-moving population(s) on long-chain SAMs. In particular, on longer (16-18 carbon) alkylsilane monolayers, the probe molecule exhibited far fewer desorption-mediated "flights" than on short (4-6 carbon) monolayers. Additionally, probes on the longer chain surfaces were much more likely to exhibit extended surface residence times as opposed to short transient surface visits.
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Affiliation(s)
- Nathaniel Nelson
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
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Armendariz KP, Huckabay HA, Livanec PW, Dunn RC. Single molecule probes of membrane structure: orientation of BODIPY probes in DPPC as a function of probe structure. Analyst 2012; 137:1402-8. [PMID: 22322157 DOI: 10.1039/c2an16255e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Single molecule fluorescence measurements have recently been used to probe the orientation of fluorescent lipid analogs doped into lipid films at trace levels. Using defocused polarized total internal reflection fluorescence microscopy (PTIRF-M), these studies have shown that fluorophore orientation responds to changes in membrane surface pressure and composition, providing a molecular level marker of membrane structure. Here we extend those studies by characterizing the single molecule orientations of six related BODIPY probes doped into monolayers of DPPC. Langmuir-Blodgett monolayers transferred at various surface pressures are used to compare the response from fluorescent lipid analogs in which the location of the BODIPY probe is varied along the length of the acyl chain. For each BODIPY probe location along the chain, comparisons are made between analogs containing phosphocholine and smaller fatty acid headgroups. Together these studies show a general propensity of the BODIPY analogs to insert into membranes with the BODIPY probe aligned along the acyl chains or looped back to interact with the headgroups. For all BODIPY probes studied, a bimodal orientation distribution is observed which is sensitive to surface pressure, with the population of BODIPY probes aligned along the acyl chains increasing with elevated surface pressure. Trends in the single molecule orientations for the six analogs reveal a configuration where optimal placement of the BODIPY probe within the acyl chain maximizes its sensitivity to the surrounding membrane structure. These results are discussed in terms of balancing the effects of headgroup association with acyl chain length in designing the optimal placement of the BODIPY probe.
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Affiliation(s)
- Kevin P Armendariz
- Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, USA
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Gözen I, Jesorka A. Instrumental Methods to Characterize Molecular Phospholipid Films on Solid Supports. Anal Chem 2012; 84:822-38. [DOI: 10.1021/ac203126f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Irep Gözen
- Department of Chemical and Biological
Engineering, Chalmers University of Technology, Kemivägen 10, 41296 Göteborg, Sweden
| | - Aldo Jesorka
- Department of Chemical and Biological
Engineering, Chalmers University of Technology, Kemivägen 10, 41296 Göteborg, Sweden
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Das S, Powe AM, Baker GA, Valle B, El-Zahab B, Sintim HO, Lowry M, Fakayode SO, McCarroll ME, Patonay G, Li M, Strongin RM, Geng ML, Warner IM. Molecular Fluorescence, Phosphorescence, and Chemiluminescence Spectrometry. Anal Chem 2011; 84:597-625. [DOI: 10.1021/ac202904n] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Susmita Das
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Aleeta M. Powe
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, United States
| | - Gary A. Baker
- Department of Chemistry, University of Missouri−Columbia, Columbia, Missouri 65211-7600, United States
| | - Bertha Valle
- Department of Chemistry, Texas Southern University, Houston, Texas 77004, United States
| | - Bilal El-Zahab
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Herman O. Sintim
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Mark Lowry
- Department of Chemistry, Portland State University, Portland, Oregon 97207, United States
| | - Sayo O. Fakayode
- Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, United States
| | - Matthew E. McCarroll
- Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, Illinois 62901-4409, United States
| | - Gabor Patonay
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302-4098, United States
| | - Min Li
- Process Development Center, Albemarle Corporation, Baton Rouge, Louisiana 70805, United States
| | - Robert M. Strongin
- Department of Chemistry, Portland State University, Portland, Oregon 97207, United States
| | - Maxwell L. Geng
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Isiah M. Warner
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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Parisio G, Marini A, Biancardi A, Ferrarini A, Mennucci B. Polarity-sensitive fluorescent probes in lipid bilayers: bridging spectroscopic behavior and microenvironment properties. J Phys Chem B 2011; 115:9980-9. [PMID: 21770447 DOI: 10.1021/jp205163w] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We have studied the emission features of the fluorescent polarity-sensitive probes known as Prodan and Laurdan in a liquid-crystalline DPPC bilayer. To this purpose, we have combined high-level quantum mechanical electronic structure calculations with a molecular field theory for the positional-orientational-conformational distribution of the probes, in their ground and excited states, inside of the lipid bilayer, taking into account at both levels the nonuniformity and anisotropy of the environment. Thus, we can interpret the features of the fluorescence spectra of Prodan and Laurdan in relation to the position and orientation of their chromophore in the bilayer. We have found that the environment polarity is not sufficient to explain the large red shifts experimentally observed and that specific effects due to hydrogen bonding must be considered. We show that the orientation of the probe is important in determining the accessibility to water of the H-bond-acceptor group; in the case of Laurdan interesting conformational effects are highlighted.
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Affiliation(s)
- Giulia Parisio
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131 Padova, Italy
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