1
|
Aguilar J, Malacrida L, Gunther G, Torrado B, Torres V, Urbano BF, Sánchez SA. Cells immersed in collagen matrices show a decrease in plasma membrane fluidity as the matrix stiffness increases. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184176. [PMID: 37328024 DOI: 10.1016/j.bbamem.2023.184176] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 05/10/2023] [Accepted: 05/15/2023] [Indexed: 06/18/2023]
Abstract
Cells are constantly adapting to maintain their identity in response to the surrounding media's temporal and spatial heterogeneity. The plasma membrane, which participates in the transduction of external signals, plays a crucial role in this adaptation. Studies suggest that nano and micrometer areas with different fluidities at the plasma membrane change their distribution in response to external mechanical signals. However, investigations linking fluidity domains with mechanical stimuli, specifically matrix stiffness, are still in progress. This report tests the hypothesis that the stiffness of the extracellular matrix can modify the equilibrium of areas with different order in the plasma membrane, resulting in changes in overall membrane fluidity distribution. We studied the effect of matrix stiffness on the distribution of membrane lipid domains in NIH-3 T3 cells immersed in matrices of varying concentrations of collagen type I, for 24 or 72 h. The stiffness and viscoelastic properties of the collagen matrices were characterized by rheometry, fiber sizes were measured by Scanning Electron Microscopy (SEM) and the volume occupied by the fibers by second harmonic generation imaging (SHG). Membrane fluidity was measured using the fluorescent dye LAURDAN and spectral phasor analysis. The results demonstrate that an increase in collagen stiffness alters the distribution of membrane fluidity, leading to an increasing amount of the LAURDAN fraction with a high degree of packing. These findings suggest that changes in the equilibrium of fluidity domains could represent a versatile and refined component of the signal transduction mechanism for cells to respond to the highly heterogeneous matrix structural composition. Overall, this study sheds light on the importance of the plasma membrane's role in adapting to the extracellular matrix's mechanical cues.
Collapse
Affiliation(s)
- Joao Aguilar
- Laboratorio de Interacciones Macromoleculares (LIMM), Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile
| | - Leonel Malacrida
- Departamento de Fisiopatología, Hospital de Clínicas, Universidad de la República, Montevideo, Uruguay; Advanced Bioimaging Unit, Institut Pasteur Montevideo, Universidad de la República, Montevideo, Uruguay
| | - German Gunther
- Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Belén Torrado
- Biomedical Engineering Department, University of California at Irvine, California, USA
| | - Viviana Torres
- Departamento de Bioquímica, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Bruno F Urbano
- Laboratorio de Interacciones Macromoleculares (LIMM), Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile
| | - Susana A Sánchez
- Laboratorio de Interacciones Macromoleculares (LIMM), Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile.
| |
Collapse
|
2
|
Mangiarotti A, Siri M, Tam NW, Zhao Z, Malacrida L, Dimova R. Biomolecular condensates modulate membrane lipid packing and hydration. Nat Commun 2023; 14:6081. [PMID: 37770422 PMCID: PMC10539446 DOI: 10.1038/s41467-023-41709-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 09/15/2023] [Indexed: 09/30/2023] Open
Abstract
Membrane wetting by biomolecular condensates recently emerged as a key phenomenon in cell biology, playing an important role in a diverse range of processes across different organisms. However, an understanding of the molecular mechanisms behind condensate formation and interaction with lipid membranes is still missing. To study this, we exploited the properties of the dyes ACDAN and LAURDAN as nano-environmental sensors in combination with phasor analysis of hyperspectral and lifetime imaging microscopy. Using glycinin as a model condensate-forming protein and giant vesicles as model membranes, we obtained vital information on the process of condensate formation and membrane wetting. Our results reveal that glycinin condensates display differences in water dynamics when changing the salinity of the medium as a consequence of rearrangements in the secondary structure of the protein. Remarkably, analysis of membrane-condensates interaction with protein as well as polymer condensates indicated a correlation between increased wetting affinity and enhanced lipid packing. This is demonstrated by a decrease in the dipolar relaxation of water across all membrane-condensate systems, suggesting a general mechanism to tune membrane packing by condensate wetting.
Collapse
Affiliation(s)
- Agustín Mangiarotti
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476, Potsdam, Germany.
| | - Macarena Siri
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476, Potsdam, Germany
| | - Nicky W Tam
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476, Potsdam, Germany
| | - Ziliang Zhao
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476, Potsdam, Germany
- Leibniz Institute of Photonic Technology e.V., Albert-Einstein-Straße 9, 07745, Jena, Germany
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-University Jena, Max-Wien Platz 1, 07743, Jena, Germany
| | - Leonel Malacrida
- Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
- Advanced Bioimaging Unit, Institut Pasteur of Montevideo and Universidad de la República, Montevideo, Uruguay.
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476, Potsdam, Germany.
| |
Collapse
|
3
|
Addabbo RM, Hutchinson RB, Allaman HJ, Dalphin MD, Mecha MF, Liu Y, Staikos A, Cavagnero S. Critical Beginnings: Selective Tuning of Solubility and Structural Accuracy of Newly Synthesized Proteins by the Hsp70 Chaperone System. J Phys Chem B 2023; 127:3990-4014. [PMID: 37130318 PMCID: PMC10829761 DOI: 10.1021/acs.jpcb.2c08485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Proteins are particularly prone to aggregation immediately after release from the ribosome, and it is therefore important to elucidate the role of chaperones during these key steps of protein life. The Hsp70 and trigger factor (TF) chaperone systems interact with nascent proteins during biogenesis and immediately post-translationally. It is unclear, however, whether these chaperones can prevent formation of soluble and insoluble aggregates. Here, we address this question by monitoring the solubility and structural accuracy of globin proteins biosynthesized in an Escherichia coli cell-free system containing different concentrations of the bacterial Hsp70 and TF chaperones. We find that Hsp70 concentrations required to grant solubility to newly synthesized proteins are extremely sensitive to client-protein sequence. Importantly, Hsp70 concentrations yielding soluble client proteins are insufficient to prevent formation of soluble aggregates. In fact, for some aggregation-prone protein variants, avoidance of soluble-aggregate formation demands Hsp70 concentrations that exceed cellular levels in E. coli. In all, our data highlight the prominent role of soluble aggregates upon nascent-protein release from the ribosome and show the limitations of the Hsp70 chaperone system in the case of highly aggregation-prone proteins. These results demonstrate the need to devise better strategies to prevent soluble-aggregate formation upon release from the ribosome.
Collapse
Affiliation(s)
- Rayna M. Addabbo
- Biophysics Graduate Degree Program, University of Wisconsin-Madison, Madison, WI, 53706, U.S.A
| | - Rachel B. Hutchinson
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, U.S.A
| | - Heather J. Allaman
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, U.S.A
| | - Matthew D. Dalphin
- Biophysics Graduate Degree Program, University of Wisconsin-Madison, Madison, WI, 53706, U.S.A
| | - Miranda F. Mecha
- Biophysics Graduate Degree Program, University of Wisconsin-Madison, Madison, WI, 53706, U.S.A
| | - Yue Liu
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, U.S.A
| | - Alexios Staikos
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, U.S.A
| | - Silvia Cavagnero
- Biophysics Graduate Degree Program, University of Wisconsin-Madison, Madison, WI, 53706, U.S.A
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, U.S.A
| |
Collapse
|
4
|
Díaz M, Malacrida L. Advanced Fluorescence Microscopy Methods to Study Dynamics of Fluorescent Proteins In Vivo. Methods Mol Biol 2023; 2564:53-74. [PMID: 36107337 DOI: 10.1007/978-1-0716-2667-2_3] [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] [Indexed: 06/15/2023]
Abstract
Fluorescent proteins are standard tools for addressing biological questions in a cell biology laboratory. The genetic tagging of protein of interest with fluorescent proteins opens the opportunity to follow them in vivo and to understand their interactions and dynamics. In addition, the latest advances in optical microscopy image acquisition and processing allow us to study many cellular processes in vivo. Techniques such as fluorescence lifetime microscopy and hyperspectral imaging provide valuable tools for understanding fluorescent protein interactions and their photophysics. Finally, fluorescence fluctuation analysis opens the possibility to address questions of molecular diffusion, protein-protein interactions, and oligomerization, among others, yielding quantitative information on the subject of study. This chapter will cover some of the more important advances in cutting-edge technologies and methods that, combined with fluorescent proteins, open new frontiers for biological studies.
Collapse
Affiliation(s)
- Marcela Díaz
- Advanced Bioimaging Unit, Institut Pasteur of Montevideo & Universidad de la República, Montevideo, Uruguay
| | - Leonel Malacrida
- Advanced Bioimaging Unit, Institut Pasteur of Montevideo & Universidad de la República, Montevideo, Uruguay.
- Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
| |
Collapse
|
5
|
Villar SF, Dalla-Rizza J, Möller MN, Ferrer-Sueta G, Malacrida L, Jameson DM, Denicola A. Fluorescence Lifetime Phasor Analysis of the Decamer-Dimer Equilibrium of Human Peroxiredoxin 1. Int J Mol Sci 2022; 23:5260. [PMID: 35563654 PMCID: PMC9100220 DOI: 10.3390/ijms23095260] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 11/22/2022] Open
Abstract
Protein self-assembly is a common feature in biology and is often required for a myriad of fundamental processes, such as enzyme activity, signal transduction, and transport of solutes across membranes, among others. There are several techniques to find and assess homo-oligomer formation in proteins. Naturally, all these methods have their limitations, meaning that at least two or more different approaches are needed to characterize a case study. Herein, we present a new method to study protein associations using intrinsic fluorescence lifetime with phasors. In this case, the method is applied to determine the equilibrium dissociation constant (KD) of human peroxiredoxin 1 (hPrx1), an efficient cysteine-dependent peroxidase, that has a quaternary structure comprised of five head-to-tail homodimers non-covalently arranged in a decamer. The hPrx1 oligomeric state not only affects its activity but also its association with other proteins. The excited state lifetime of hPrx1 has distinct values at high and low concentrations, suggesting the presence of two different species. Phasor analysis of hPrx1 emission lifetime allowed for the identification and quantification of hPrx1 decamers, dimers, and their mixture at diverse protein concentrations. Using phasor algebra, we calculated the fraction of hPrx1 decamers at different concentrations and obtained KD (1.1 × 10-24 M4) and C0.5 (1.36 μM) values for the decamer-dimer equilibrium. The results were validated and compared with size exclusion chromatography. In addition, spectral phasors provided similar results despite the small differences in emission spectra as a function of hPrx1 concentration. The phasor approach was shown to be a highly sensitive and quantitative method to assess protein oligomerization and an attractive addition to the biophysicist's toolkit.
Collapse
Affiliation(s)
- Sebastián F. Villar
- Laboratorio de Fisicoquímica Biológica, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay; (S.F.V.); (J.D.-R.); (M.N.M.); (G.F.-S.)
- Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo 11800, Uruguay
| | - Joaquín Dalla-Rizza
- Laboratorio de Fisicoquímica Biológica, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay; (S.F.V.); (J.D.-R.); (M.N.M.); (G.F.-S.)
| | - Matías N. Möller
- Laboratorio de Fisicoquímica Biológica, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay; (S.F.V.); (J.D.-R.); (M.N.M.); (G.F.-S.)
- Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo 11800, Uruguay
| | - Gerardo Ferrer-Sueta
- Laboratorio de Fisicoquímica Biológica, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay; (S.F.V.); (J.D.-R.); (M.N.M.); (G.F.-S.)
- Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo 11800, Uruguay
| | - Leonel Malacrida
- Advanced Bioimaging Unit, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay;
- Departamento de Fisiopatología, Hospital de Clínicas, Universidad de la República, Montevideo 11600, Uruguay
| | - David M. Jameson
- Department of Cell and Molecular Biology, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Ana Denicola
- Laboratorio de Fisicoquímica Biológica, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay; (S.F.V.); (J.D.-R.); (M.N.M.); (G.F.-S.)
- Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo 11800, Uruguay
| |
Collapse
|
6
|
Socas LB, Ambroggio EE. Introducing the multi-dimensional spectral phasors: a tool for the analysis of fluorescence excitation-emission matrices. Methods Appl Fluoresc 2022; 10. [PMID: 35139496 DOI: 10.1088/2050-6120/ac5389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 02/09/2022] [Indexed: 11/12/2022]
Abstract
The use of phasors to analyze fluorescence data was first introduced for time-resolved studies for a simpler mathematical analysis of the fluorescence-decay curves. Recently, this approach was extended to steady-state experiments with the introduction of the spectral phasors (SP), derived from the Fourier transform of the fluorescence emission spectrum. In this work, we revise key mathematical aspects that lead to an interpretation of SP as the characteristic function of a probability distribution. This formalism allows us to introduce a new tool, called multi-dimensional spectral phasor (MdSP) that seize, not only the information from the emission spectrum, but from the full excitation-emission matrix (EEM). In addition, we developed a homemade open-source Java software to facilitate the MdSP data processing. Due to this mathematical conceptualization, we settled a mechanism for the use of MdSP as a tool to tackle spectral signal unmixing problems in a more accurate way than SP. As a proof of principle, with the use of MdSP we approach two important biophysical questions: protein conformational changes and protein-ligand interactions. Specifically, we experimentally measure the EEM changes upon denaturation of human serum albumin (HSA) or during its association with the fluorescence dye 1,8-anilinonaphtalene sulphate (ANS) detected via tryptophan-ANS Förster Resonance Energy Transfer (FRET). In this sense, MdSP allows us to obtain information of the system in a simpler and finer way than the traditional SP. Specifically, understanding a protein's EEM as a molecular fingerprint opens new doors for the use of MdSP as a tool to analyze and comprehend protein conformational changes and interactions.
Collapse
Affiliation(s)
- Luis Bp Socas
- Química Biológica, Centro de Investigaciones en Química Biológica de Córdoba, Haya de la Torre y Medina Allende s/n, Cordoba, Córdoba, X5000HUA, ARGENTINA
| | - Ernesto Esteban Ambroggio
- Química Biológica, CIQUIBIC Química Biológica, Haya de la Torre y Medina Allende s/n, Cordoba, X5000HUA, ARGENTINA
| |
Collapse
|
7
|
Mangiarotti A, Bagatolli LA. Impact of macromolecular crowding on the mesomorphic behavior of lipid self-assemblies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183728. [PMID: 34416246 DOI: 10.1016/j.bbamem.2021.183728] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/19/2021] [Accepted: 08/06/2021] [Indexed: 11/26/2022]
Abstract
Using LAURDAN fluorescence we observed that water dynamics measured at the interface of DOPC bilayers can be differentially regulated by the presence of crowded suspensions of different proteins (HSA, IgG, Gelatin) and PEG, under conditions where the polymers are not in direct molecular contact with the lipid interface. Specifically, we found that the decrease in water dipolar relaxation at the membrane interface correlates with an increased fraction of randomly oriented (or random coil) configurations in the polymers, as Gelatin > PEG > IgG > HSA. By using the same experimental strategy, we also demonstrated that structural transitions from globular to extended conformations in proteins can induce transitions between lamellar and non-lamellar phases in mixtures of DOPC and monoolein. Independent experiments using Raman spectroscopy showed that aqueous suspensions of polymers exhibiting high proportions of randomly oriented conformations display increased fractions of tetracoordinated water, a configuration that is dominant in ice. This indicates a greater capacity of this type of structure for polarizing water and consequently reducing its chemical activity. This effect is in line with one of the tenets of the Association Induction Hypothesis, which predicts a long-range dynamic structuring of water molecules via their interactions with proteins (or other polymers) showing extended conformations. Overall, our results suggest a crucial role of water in promoting couplings between structural changes in macromolecules and supramolecular arrangements of lipids. This mechanism may be of relevance to cell structure/function when the crowded nature of the intracellular milieu is considered.
Collapse
Affiliation(s)
- Agustín Mangiarotti
- Instituto de Investigación Médica Mercedes y Martín Ferreyra - INIMEC (CONICET) - Universidad Nacional de Córdoba, Friuli 2434, 5016 Córdoba, Argentina
| | - Luis A Bagatolli
- Instituto de Investigación Médica Mercedes y Martín Ferreyra - INIMEC (CONICET) - Universidad Nacional de Córdoba, Friuli 2434, 5016 Córdoba, Argentina; Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
| |
Collapse
|
8
|
Malacrida L, Ranjit S, Jameson DM, Gratton E. The Phasor Plot: A Universal Circle to Advance Fluorescence Lifetime Analysis and Interpretation. Annu Rev Biophys 2021; 50:575-593. [PMID: 33957055 DOI: 10.1146/annurev-biophys-062920-063631] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The phasor approach to fluorescence lifetime imaging has become a common method to analyze complicated fluorescence signals from biological samples. The appeal of the phasor representation of complex fluorescence decays in biological systems is that a visual representation of the decay of entire cells or tissues can be used to easily interpret fundamental biological states related to metabolism and oxidative stress. Phenotyping based on autofluorescence provides new avenues for disease characterization and diagnostics. The phasor approach is a transformation of complex fluorescence decays that does not use fits to model decays and therefore has the same information content as the original data. The phasor plot is unique for a given system, is highly reproducible, and provides a robust method to evaluate the existence of molecular interactions such as Förster resonance energy transfer or the response of ion indicators. Recent advances permitquantification of multiple components from phasor plots in fluorescence lifetime imaging microscopy, which is not presently possible using data fitting methods, especially in biological systems.
Collapse
Affiliation(s)
- Leonel Malacrida
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California 92697, USA; .,Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, 11600 Montevideo, Uruguay.,Advanced Bioimaging Unit, Institut Pasteur Montevideo and Universidad de la República-Uruguay, 11400 Montevideo, Uruguay
| | - Suman Ranjit
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California 92697, USA; .,Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC 20057, USA
| | - David M Jameson
- Department of Cell and Molecular Biology, University of Hawaii at Manoa, Honolulu, Hawaii 96813, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California 92697, USA;
| |
Collapse
|
9
|
Gunther G, Malacrida L, Jameson DM, Gratton E, Sánchez SA. LAURDAN since Weber: The Quest for Visualizing Membrane Heterogeneity. Acc Chem Res 2021; 54:976-987. [PMID: 33513300 PMCID: PMC8552415 DOI: 10.1021/acs.accounts.0c00687] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Any chemist studying the interaction of molecules with lipid assemblies will eventually be confronted by the topic of membrane bilayer heterogeneity and may ultimately encounter the heterogeneity of natural membranes. In artificial bilayers, heterogeneity is defined by phase segregation that can be in the nano- and micrometer range. In biological bilayers, heterogeneity is considered in the context of small (10-200 nm) sterol and sphingolipid-enriched heterogeneous and highly dynamic domains. Several techniques can be used to assess membrane heterogeneity in living systems. Our approach is to use a fluorescent reporter molecule immersed in the bilayer, which, by changes in its spectroscopic properties, senses physical-chemistry aspects of the membrane. This dye in combination with microscopy and fluctuation techniques can give information about membrane heterogeneity at different temporal and spatial levels: going from average fluidity to number and diffusion coefficient of nanodomains. LAURDAN (6-dodecanoyl-2-(dimethylamino) naphthalene), is a fluorescent probe designed and synthesized in 1979 by Gregorio Weber with the purpose to study the phenomenon of dipolar relaxation. The spectral displacement observed when LAURDAN is either in fluid or gel phase permitted the use of the technique in the field of membrane dynamics. The quantitation of the spectral displacement was first addressed by the generalized polarization (GP) function in the cuvette, a ratio of the difference in intensity at two wavelengths divided by their sum. In 1997, GP measurements were done for the first time in the microscope, adding to the technique the spatial resolution and allowing the visualization of lipid segregation both in liposomes and cells. A new prospective to the membrane heterogeneity was obtained when LAURDAN fluorescent lifetime measurements were done in the microscope. Two channel lifetime imaging provides information on membrane polarity and dipole relaxation (the two parameters responsible for the spectral shift of LAURDAN), and the application of phasor analysis allows pixel by pixel understanding of these two parameters in the membrane. To increase temporal resolution, LAURDAN GP was combined with fluctuation correlation spectroscopy (FCS) and the motility of nanometric highly packed structures in biological membranes was registered. Lately the application of phasor analysis to spectral images from membranes labeled with LAURDAN allows us to study the full spectra pixel by pixel in an image. All these methodologies, using LAURDAN, offer the possibility to address different properties of membranes depending on the question being asked. In this Account, we will focus on the principles, advantages, and limitations of different approaches to orient the reader to select the most appropriate technique for their research.
Collapse
Affiliation(s)
- German Gunther
- Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Sergio Livingstone P. 1007, Santiago 8380492, Chile
| | - Leonel Malacrida
- Advanced Microscopy and Biophotonics Unit, Hospital de Clínicas, Universidad de la República, Montevideo-Uruguay. Advanced Bioimaging Unit, Institut Pasteur Montevideo, Av. Italia s/n, 90600 Montevideo, Uruguay
| | - David M Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo Street, Biosciences 222, Honolulu, Hawaii 96813, United States
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, 3210 Natural Sciences II, University of California, Irvine, Irvine, California 92697-2725, United States
| | - Susana A Sánchez
- Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Edmundo Larenas 129, Concepción 4070371, Chile
| |
Collapse
|
10
|
Addabbo RM, Dalphin MD, Mecha MF, Liu Y, Staikos A, Guzman-Luna V, Cavagnero S. Complementary Role of Co- and Post-Translational Events in De Novo Protein Biogenesis. J Phys Chem B 2020; 124:6488-6507. [DOI: 10.1021/acs.jpcb.0c03039] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Rayna M. Addabbo
- Biophysics Graduate Degree Program, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Matthew D. Dalphin
- Biophysics Graduate Degree Program, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Miranda F. Mecha
- Biophysics Graduate Degree Program, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Yue Liu
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Alexios Staikos
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Valeria Guzman-Luna
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Silvia Cavagnero
- Biophysics Graduate Degree Program, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| |
Collapse
|
11
|
Vallmitjana A, Dvornikov A, Torrado B, Jameson DM, Ranjit S, Gratton E. Resolution of 4 components in the same pixel in FLIM images using the phasor approach. Methods Appl Fluoresc 2020; 8:035001. [PMID: 32235070 DOI: 10.1088/2050-6120/ab8570] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In several cellular systems, the phasor FLIM approach has shown the existence of more than 2 components in the same pixel, a typical example being free and bound NADH. In order to properly quantify the concentrations and the spatial distributions of fluorescence components associated with different molecular species we developed a general method to resolve 3 and 4 components in the same pixel using the phasor approach. The method is based on the law of linear combination of components valid after transformation of the decay curves to phasors for each pixel in the image. In principle, the linear combination rule is valid for an arbitrary number of components. For 3 components we use only the phasor position for the first harmonic, which has a small error, while for 4 components we need the phasor location at higher harmonics that have intrinsically more noise. As a result of the noise in the higher harmonics, caused by limited photon statistics, we are able to use linear algebra to resolve 4 components given the position of the phasors of 4 independent components in mixtures of dyes and 3 components for dyes in cellular systems.
Collapse
Affiliation(s)
- Alexander Vallmitjana
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, United States of America
| | | | | | | | | | | |
Collapse
|
12
|
Ulku A, Ardelean A, Antolovic M, Weiss S, Charbon E, Bruschini C, Michalet X. Wide-field time-gated SPAD imager for phasor-based FLIM applications. Methods Appl Fluoresc 2020; 8:024002. [PMID: 31968310 PMCID: PMC8827132 DOI: 10.1088/2050-6120/ab6ed7] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We describe the performance of a new wide area time-gated single-photon avalanche diode (SPAD) array for phasor-FLIM, exploring the effect of gate length, gate number and signal intensity on the measured lifetime accuracy and precision. We conclude that the detector functions essentially as an ideal shot noise limited sensor and is capable of video rate FLIM measurement. The phasor approach used in this work appears ideally suited to handle the large amount of data generated by this type of very large sensor (512 × 512 pixels), even in the case of small number of gates and limited photon budget.
Collapse
Affiliation(s)
- Arin Ulku
- AQUA Lab, Ecole Polytechnique Fédérale de
Lausanne (EPFL), Neuchâtel, Switzerland
| | - Andrei Ardelean
- AQUA Lab, Ecole Polytechnique Fédérale de
Lausanne (EPFL), Neuchâtel, Switzerland
| | - Michel Antolovic
- AQUA Lab, Ecole Polytechnique Fédérale de
Lausanne (EPFL), Neuchâtel, Switzerland
| | - Shimon Weiss
- Department of Chemistry & Biochemistry, University of
California at Los Angeles (UCLA), Los Angeles, California, United States of
America
| | - Edoardo Charbon
- AQUA Lab, Ecole Polytechnique Fédérale de
Lausanne (EPFL), Neuchâtel, Switzerland
| | - Claudio Bruschini
- AQUA Lab, Ecole Polytechnique Fédérale de
Lausanne (EPFL), Neuchâtel, Switzerland
| | - Xavier Michalet
- Department of Chemistry & Biochemistry, University of
California at Los Angeles (UCLA), Los Angeles, California, United States of
America
| |
Collapse
|
13
|
Nguyen H, Ward WS, James NG. Spatial and temporal resolution of mORC4 fluorescent variants reveals structural requirements for achieving higher order self-association and pronuclei entry. Methods Appl Fluoresc 2019; 7:035002. [PMID: 30865939 PMCID: PMC6636821 DOI: 10.1088/2050-6120/ab0f57] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The Origin Replication Complex (ORC), which is a multi-subunit protein complex composed of six proteins ORC1-6, is essential for initiating licensing at DNA replication origins. We have previously reported that ORC4 has an alternative function wherein it forms a cage surrounding the extruded chromatin in female meiosis and is required for polar body extrusion (PBE). As this is a highly unexpected finding for protein that normally binds DNA, we tested whether ORC4 can actually form larger, higher order structures, which would be necessary to form a cage-like structure. We generated two fluorescent constructs of mouse ORC4, mORC4-EGFP and mORC4-FlAsH, to examine its spatial dynamics during oocyte activation in live cells. We show that both constructs were primarily monomeric throughout the embryo but self-association into larger units was detected with both probes. However, mORC4-FlAsH clearly showed higher order self-association and unique spatial distribution while mORC4-EGFP failed to form large structures during Anaphase II. Interestingly, both variants were found in the pronuclei suggesting that its role in DNA licensing is still functional. Our results with both constructs support the prediction that ORC4 can form higher order structures in the cytoplasm, suggesting that it is possible to form a cage-like structure. The finding that FlAsH labeled ORC4 formed demonstrably larger higher order structures than ORC4-GFP suggests that ORC4 oligomerization is sensitive to the bulky addition of GFP at its carboxy terminus.
Collapse
Affiliation(s)
- Hieu Nguyen
- Department of Anatomy, Biochemistry, and Physiology, John A. Burns School of Medicine, 1960 East-West Rd., University of Hawaii, Honolulu, HI 96822, United States of America
| | | | | |
Collapse
|
14
|
Gautam S, Gupta MN. Solid state fluorescence of proteins in high throughput mode and its applications. F1000Res 2019; 2:82. [PMID: 30997030 PMCID: PMC6441877 DOI: 10.12688/f1000research.2-82.v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/07/2019] [Indexed: 11/24/2022] Open
Abstract
Direct comparison between fluorescence spectra of a sample in solution and solid state form is valuable to monitor the changes in protein structure when it is “dried” or immobilized on a solid surface (for biocatalysis or sensor applications). We describe here a simple method for recording fluorescence emission spectra of protein powders without using any dedicated accessory for solid samples in a high-throughput format. The 96-well plate used in our studies, was coated black from all the sides and the excitation and emission paths are identical and are from the top of the well. These two features minimize scatter and provide fairly noise free spectra. Even then the fluorescence intensity may be dependent upon many factors such as the extent of protein aggregation, morphology and sizes of the protein particles. Hence, (changes in) λ
max emission may be a more reliable metric in the case of fluorescence spectra of proteins in the solid state. However, any large changes in the intensity could indicate changes in the microenvironment of the fluorophore. The fluorescence emission spectra were blue-shifted (4 to 9 nm), showed an increase in the intensity for different proteins studied upon lyophilization, and were similar to what has been reported by others using available commercial accessories for solid state samples. After validating that our method worked just as well as the dedicated accessories, we applied the method to compare the fluorescence emission spectra of α-chymotrypsin in solution, precipitated form, and the lyophilized powder form. We further examined the fluorescence emission spectra of green fluorescent protein (GFP) in solution and solid form. We also analyzed fluorescence resonance energy transfer (FRET) between tryptophan (Trp57) and the cyclic chromophore of GFP. These findings pointed towards the change in the microenvironment around the cyclic chromophore in GFP upon lyophilization.
Collapse
Affiliation(s)
- Saurabh Gautam
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Munishwar N Gupta
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India
| |
Collapse
|
15
|
Chen SJ, Sinsuebphon N, Rudkouskaya A, Barroso M, Intes X, Michalet X. In vitro and in vivo phasor analysis of stoichiometry and pharmacokinetics using short-lifetime near-infrared dyes and time-gated imaging. JOURNAL OF BIOPHOTONICS 2019; 12:e201800185. [PMID: 30421551 PMCID: PMC6559731 DOI: 10.1002/jbio.201800185] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 10/08/2018] [Accepted: 11/11/2018] [Indexed: 05/22/2023]
Abstract
We introduce a simple new approach for time-resolved multiplexed analysis of complex systems using near-infrared (NIR) dyes, applicable to in vitro and in vivo studies. We show that fast and precise in vitro quantification of NIR fluorophores' short (subnanosecond) lifetime and stoichiometry can be done using phasor analysis, a computationally efficient and user-friendly representation of complex fluorescence intensity decays obtained with pulsed laser excitation and time-gated camera imaging. We apply this approach to the study of binding equilibria by Förster resonant energy transfer using two different model systems: primary/secondary antibody binding in vitro and ligand/receptor binding in cell cultures. We then extend it to dynamic imaging of the pharmacokinetics of transferrin engagement with the transferrin receptor in live mice, elucidating the kinetics of differential transferrin accumulation in specific organs, straightforwardly differentiating specific from nonspecific binding. Our method, implemented in a freely-available software, has the advantage of time-resolved NIR imaging, including better tissue penetration and background-free imaging, but simplifies and considerably speeds up data processing and interpretation, while remaining quantitative. These advances make this method attractive and of broad applicability for in vitro and in vivo molecular imaging and could be extended to applications as diverse as image-guided surgery or optical tomography.
Collapse
Affiliation(s)
- Sez-Jade Chen
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York
| | - Nattawut Sinsuebphon
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York
| | - Alena Rudkouskaya
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York
| | - Margarida Barroso
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York
| | - Xavier Intes
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York
| | - Xavier Michalet
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, California
| |
Collapse
|
16
|
Sugár IP, Bonanno AP, Chong PLG. Gramicidin Lateral Distribution in Phospholipid Membranes: Fluorescence Phasor Plots and Statistical Mechanical Model. Int J Mol Sci 2018; 19:E3690. [PMID: 30469389 PMCID: PMC6274966 DOI: 10.3390/ijms19113690] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/14/2018] [Accepted: 11/15/2018] [Indexed: 11/16/2022] Open
Abstract
When using small mole fraction increments to study gramicidins in phospholipid membranes, we found that the phasor dots of intrinsic fluorescence of gramicidin D and gramicidin A in dimyristoyl-sn-glycero-3-phosphocholine (DMPC) unilamellar and multilamellar vesicles exhibit a biphasic change with peptide content at 0.143 gramicidin mole fraction. To understand this phenomenon, we developed a statistical mechanical model of gramicidin/DMPC mixtures. Our model assumes a sludge-like mixture of fluid phase and aggregates of rigid clusters. In the fluid phase, gramicidin monomers are randomly distributed. A rigid cluster is formed by a gramicidin dimer and DMPC molecules that are condensed to the dimer, following particular stoichiometries (critical gramicidin mole fractions, Xcr including 0.143). Rigid clusters form aggregates in which gramicidin dimers are regularly distributed, in some cases, even to superlattices. At Xcr, the size of cluster aggregates and regular distributions reach a local maximum. Before a similar model was developed for cholesterol/DMPC mixtures (Sugar and Chong (2012) J. Am. Chem. Soc. 134, 1164⁻1171) and here the similarities and differences are discussed between these two models.
Collapse
Affiliation(s)
- István P Sugár
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Alexander P Bonanno
- Department of Medical Genetics and Molecular Biochemistry, The Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA.
| | - Parkson Lee-Gau Chong
- Department of Medical Genetics and Molecular Biochemistry, The Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA.
| |
Collapse
|
17
|
Ranjit S, Malacrida L, Gratton E. Differences between FLIM phasor analyses for data collected with the Becker and Hickl SPC830 card and with the FLIMbox card. Microsc Res Tech 2018; 81:980-989. [PMID: 30295346 PMCID: PMC6240382 DOI: 10.1002/jemt.23061] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 05/13/2018] [Indexed: 01/31/2023]
Abstract
The phasor approach to FLIM (Fluorescence Lifetime Imaging Microscopy) is becoming popular due to the powerful fit free analysis and the visualization of the decay at each point in images of cells and tissues. However, although several implementation of the method are offered by manufactures of FLIM accessories for microscopes, the details of the conversion of the decay to phasors at each point in an image requires some consideration. Here, we show that if the decay is not properly acquired, the apparently simple phasor transformation can provide incorrect phasor plots and the results may be misinterpreted. In particular, we show the disagreement in experimental data acquired on the same samples using the two cards (FLIMbox, frequency domain and Becker & Hickl BH 830, time domain) and the effect produced by using the BH 830 card with different settings. This difference in data acquisition translates to the assignment of phasor components calculated using different acquisition parameters. This effect is already present in the original data that are not acquired with the proper parameters for the phasor conversion. We also show that the difference in the resolution of components already exists in the data acquired in the time domain when used with settings that do not allow acquisition of the fluorescence decay on a sufficient large time scale. RESEARCH HIGHLIGHTS: This paper is intended to made researchers aware of some simple requirements for the conversion of time-domain data (typically TCSPC) to phasors. The use of phasors for FLIM analysis has seen a surge of popularity. Since the phasor approach is a fit free method and has a powerful visualization of the data, it appears very simple to use. This paper shows that when the original data in the time domain is not acquired with the proper time range to cover the lifetimes in a sample, the conversion to phasors can produce very erroneous results. These results are appearing more frequently in the literature since many of the manufacturers of FLIM accessories for microscopes are now offering the phasor analysis in their software. Here, we show that the phasor transformation per se cannot correct for the problems with data acquisition and that one is misled to think that the "phasor approach" is a universal fix for the lack of the proper time range for data acquisition.
Collapse
Affiliation(s)
- Suman Ranjit
- Laboratory for Fluorescence Dynamics, University of California, Irvine, Irvine, California
| | - Leonel Malacrida
- Laboratory for Fluorescence Dynamics, University of California, Irvine, Irvine, California
- Departamento de Fisiopatología, Hospital de Clínicas, Universidad de la República, Montevideo, Uruguay
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, University of California, Irvine, Irvine, California
| |
Collapse
|
18
|
Characterization of esterase activity from an Acetomicrobium hydrogeniformans enzyme with high structural stability in extreme conditions. Extremophiles 2018; 22:781-793. [DOI: 10.1007/s00792-018-1038-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/09/2018] [Indexed: 01/06/2023]
|
19
|
Pedrote MM, de Oliveira GAP, Felix AL, Mota MF, Marques MDA, Soares IN, Iqbal A, Norberto DR, Gomes AMO, Gratton E, Cino EA, Silva JL. Aggregation-primed molten globule conformers of the p53 core domain provide potential tools for studying p53C aggregation in cancer. J Biol Chem 2018; 293:11374-11387. [PMID: 29853637 PMCID: PMC6065177 DOI: 10.1074/jbc.ra118.003285] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/10/2018] [Indexed: 12/16/2022] Open
Abstract
The functionality of the tumor suppressor p53 is altered in more than 50% of human cancers, and many individuals with cancer exhibit amyloid-like buildups of aggregated p53. An understanding of what triggers the pathogenic amyloid conversion of p53 is required for the further development of cancer therapies. Here, perturbation of the p53 core domain (p53C) with subdenaturing concentrations of guanidine hydrochloride and high hydrostatic pressure revealed native-like molten globule (MG) states, a subset of which were highly prone to amyloidogenic aggregation. We found that MG conformers of p53C, probably representing population-weighted averages of multiple states, have different volumetric properties, as determined by pressure perturbation and size-exclusion chromatography. We also found that they bind the fluorescent dye 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) and have a native-like tertiary structure that occludes the single Trp residue in p53. Fluorescence experiments revealed conformational changes of the single Trp and Tyr residues before p53 unfolding and the presence of MG conformers, some of which were highly prone to aggregation. p53C exhibited marginal unfolding cooperativity, which could be modulated from unfolding to aggregation pathways with chemical or physical forces. We conclude that trapping amyloid precursor states in solution is a promising approach for understanding p53 aggregation in cancer. Our findings support the use of single-Trp fluorescence as a probe for evaluating p53 stability, effects of mutations, and the efficacy of therapeutics designed to stabilize p53.
Collapse
Affiliation(s)
- Murilo M Pedrote
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Guilherme A P de Oliveira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908.
| | - Adriani L Felix
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Michelle F Mota
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Mayra de A Marques
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Iaci N Soares
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Anwar Iqbal
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Douglas R Norberto
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Andre M O Gomes
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Biomedical Engineering Department, University of California, Irvine, California 92697-2717
| | - Elio A Cino
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
| | - Jerson L Silva
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil.
| |
Collapse
|
20
|
Günther G, Herlax V, Lillo MP, Sandoval-Altamirano C, Belmar LN, Sánchez SA. Study of rabbit erythrocytes membrane solubilization by sucrose monomyristate using laurdan and phasor analysis. Colloids Surf B Biointerfaces 2018; 161:375-385. [DOI: 10.1016/j.colsurfb.2017.10.068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 10/06/2017] [Accepted: 10/30/2017] [Indexed: 12/13/2022]
|
21
|
Malacrida L, Jameson DM, Gratton E. A multidimensional phasor approach reveals LAURDAN photophysics in NIH-3T3 cell membranes. Sci Rep 2017; 7:9215. [PMID: 28835608 PMCID: PMC5569084 DOI: 10.1038/s41598-017-08564-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 07/11/2017] [Indexed: 11/13/2022] Open
Abstract
Mammalian cell membranes have different phospholipid composition and cholesterol content, displaying a profile of fluidity that depends on their intracellular location. Among the dyes used in membrane studies, LAURDAN has the advantage to be sensitive to the lipid composition as well as to membrane fluidity. The LAURDAN spectrum is sensitive to the lipid composition and dipolar relaxation arising from water penetration, but disentangling lipid composition from membrane fluidity can be obtained if time resolved spectra could be measured at each cell location. Here we describe a method in which spectral and lifetime information obtained in different measurements at the same plane in a cell are used in the phasor plot providing a solution to analyze multiple lifetime or spectral data through a common visualization approach. We exploit a property of phasor plots based on the reciprocal role of the phasor plot and the image. In the phasor analysis each pixel of the image is associated with a phasor and each phasor maps to pixels and features in the image. In this paper the lifetime and spectral fluorescence data are used simultaneously to determine the contribution of polarity and dipolar relaxations of LAURDAN in each pixel of an image.
Collapse
Affiliation(s)
- Leonel Malacrida
- Laboratory for Fluorescence Dynamics, Biomedical Engineering Department, University of California at Irvine, Irvine, California, USA
- Área de Investigación Respiratoria, Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
- Analytical Biochemistry and Proteomics Unit, Institut Pasteur of Montevideo, Montevideo, Uruguay
| | - David M Jameson
- Department Cell and Molecular Biology, University of Hawai'i at Manoa, John A. Burns School of Medicine, Honolulu, HI, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Biomedical Engineering Department, University of California at Irvine, Irvine, California, USA.
| |
Collapse
|
22
|
Ranjit S, Dvornikov A, Dobrinskikh E, Wang X, Luo Y, Levi M, Gratton E. Measuring the effect of a Western diet on liver tissue architecture by FLIM autofluorescence and harmonic generation microscopy. BIOMEDICAL OPTICS EXPRESS 2017; 8:3143-3154. [PMID: 28717559 PMCID: PMC5508820 DOI: 10.1364/boe.8.003143] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/13/2017] [Accepted: 05/19/2017] [Indexed: 05/12/2023]
Abstract
The phasor approach to auto-fluorescence lifetime imaging was used to identify and characterize a long lifetime species (LLS) (~7.8 ns) in livers of mice fed with a Western diet. The size of the areas containing this LLS species depends on the type of diet and the size distribution shows Western diet has much larger LLS sizes. Combination of third harmonic generation images with FLIM identified the LLS species with fat droplets and the droplet size distribution was estimated. Second harmonic generation microscopy combined with phasor FLIM shows that there is an increase in fibrosis with a Western diet. A new decomposition in three components of the phasor plot shows that a Western diet is correlated with a higher fraction of free NADH, signifying more reducing condition and more glycolytic condition. Multiparametric analysis of phasor distribution shows that from the distribution of phasor points, a Western diet fed versus a low fat diet fed samples of mice livers can be separated. The phasor approach for the analysis of FLIM images of autofluorescence in liver specimens can result in discovery of new fluorescent species and then these new fluorescent species can help assess tissue architecture. Finally integrating FLIM and second and third harmonic analysis provides a measure of the advancement of fibrosis as an effect of diet.
Collapse
Affiliation(s)
- Suman Ranjit
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Alexander Dvornikov
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Evgenia Dobrinskikh
- Departments of Medicine, University of Colorado-Anschutz Medical Campus, Aurora, Colorado, USA
| | - Xiaoxin Wang
- Departments of Medicine, University of Colorado-Anschutz Medical Campus, Aurora, Colorado, USA
| | - Yuhuan Luo
- Departments of Medicine, University of Colorado-Anschutz Medical Campus, Aurora, Colorado, USA
| | - Moshe Levi
- Departments of Medicine, University of Colorado-Anschutz Medical Campus, Aurora, Colorado, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA
| |
Collapse
|
23
|
Lopes JLS, Yoneda JS, Martins JM, DeMarco R, Jameson DM, Castro AM, Bossolan NRS, Wallace BA, Araujo APU. Environmental Factors Modulating the Stability and Enzymatic Activity of the Petrotoga mobilis Esterase (PmEst). PLoS One 2016; 11:e0158146. [PMID: 27351338 PMCID: PMC4924860 DOI: 10.1371/journal.pone.0158146] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 06/11/2016] [Indexed: 01/20/2023] Open
Abstract
Enzymes isolated from thermophilic organisms found in oil reservoirs can find applications in many fields, including the oleochemical, pharmaceutical, bioenergy, and food/dairy industries. In this study, in silico identification and recombinant production of an esterase from the extremophile bacteria Petrotoga mobilis (designated PmEst) were performed. Then biochemical, bioinformatics and structural characterizations were undertaken using a combination of synchrotron radiation circular dichroism (SRCD) and fluorescence spectroscopies to correlate PmEst stability and hydrolytic activity on different substrates. The enzyme presented a high Michaelis-Menten constant (KM 0.16 mM) and optimum activity at ~55°C for p-nitrophenyl butyrate. The secondary structure of PmEst was preserved at acid pH, but not under alkaline conditions. PmEst was unfolded at high concentrations of urea or guanidine through apparently different mechanisms. The esterase activity of PmEst was preserved in the presence of ethanol or propanol and its melting temperature increased ~8°C in the presence of these organic solvents. PmEst is a mesophilic esterase with substrate preference towards short-to medium-length acyl chains. The SRCD data of PmEst is in agreement with the prediction of an α/β protein, which leads us to assume that it displays a typical fold of esterases from this family. The increased enzyme stability in organic solvents may enable novel applications for its use in synthetic biology. Taken together, our results demonstrate features of the PmEst enzyme that indicate it may be suitable for applications in industrial processes, particularly, when the use of polar organic solvents is required.
Collapse
Affiliation(s)
- Jose L. S. Lopes
- Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
| | - Juliana S. Yoneda
- Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, United Kingdom
| | - Julia M. Martins
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - Ricardo DeMarco
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - David M. Jameson
- Department of Cell and Molecular Biology, University of Hawai’i at Manoa, Hawaii, United States of America
| | - Aline M. Castro
- Biotechnology Division, Research and Development Center, Petrobras, Brazil
| | - Nelma R. S. Bossolan
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - B. A. Wallace
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, United Kingdom
| | - Ana P. U. Araujo
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| |
Collapse
|
24
|
Rolinski OJ, McLaughlin D, Birch DJS, Vyshemirsky V. Resolving environmental microheterogeneity and dielectric relaxation in fluorescence kinetics of protein. Methods Appl Fluoresc 2016; 4:024001. [PMID: 28809166 DOI: 10.1088/2050-6120/4/2/024001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The fluorescence intensity decay of protein is easily measurable and reports on the intrinsic fluorophore-local environment interactions on the sub-nm spatial and sub-ns temporal scales, which are consistent with protein activity in numerous biomedical and industrial processes. This makes time-resolved fluorescence a perfect tool for understanding, monitoring and controlling these processes at the molecular level, but the complexity of the decay, which has been traditionally fitted to multi-exponential functions, has hampered the development of this technique over the last few decades. Using the example of tryptophan in HSA we present the alternative to the conventional approach to modelling intrinsic florescence intensity decay in protein where the key factors determining fluorescence decay, i.e. the excited-state depopulation and the dielectric relaxation (Toptygin and Brand 2000 Chem. Phys. Lett. 322 496-502), are represented by the individual relaxation functions. This allows quantification of both effects separately by determining their parameters from the global analysis of a series of fluorescence intensity decays measured at different detection wavelengths. Moreover, certain pairs of the recovered parameters of tryptophan were found to be correlated, indicating the influence of the dielectric relaxation on the transient rate of the electronic transitions. In this context the potential for the dual excited state depopulation /dielectric relaxation fluorescence lifetime sensing is discussed.
Collapse
Affiliation(s)
- Olaf J Rolinski
- Photophysics Group, Centre for Molecular Nanometrology, Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, 107 Rottenrow, Glasgow G4 0NG, UK
| | | | | | | |
Collapse
|
25
|
Malacrida L, Gratton E, Jameson DM. Model-free methods to study membrane environmental probes: a comparison of the spectral phasor and generalized polarization approaches. Methods Appl Fluoresc 2015; 3:047001. [PMID: 27182438 PMCID: PMC4862737 DOI: 10.1088/2050-6120/3/4/047001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this note, we present a discussion of the advantages and scope of model-free analysis methods applied to the popular solvatochromic probe LAURDAN, which is widely used as an environmental probe to study dynamics and structure in membranes. In particular, we compare and contrast the generalized polarization approach with the spectral phasor approach. To illustrate our points we utilize several model membrane systems containing pure lipid phases and, in some cases, cholesterol or surfactants. We demonstrate that the spectral phasor method offers definitive advantages in the case of complex systems.
Collapse
Affiliation(s)
- Leonel Malacrida
- Área de Investigación Respiratoria, Departamento de Fisiopatología, Hospital de Medicina-Facultad de Medicina, Universidad de la República, Montevideo, Uruguay; Biochemistry and Proteomic Analytical Unit, Institut Pasteur of Montevideo, Montevideo, Uruguay
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Biomedical Engineering Department, University of California at Irvine, Irvine, CA 92697, USA
| | - David M Jameson
- Department of Cell and Molecular Biology, University of Hawaii at Manoa, 651 Halo St., BSB222, Honolulu, HI 96813, USA
| |
Collapse
|
26
|
Martelo L, Fedorov A, Berberan-Santos MN. Phasor Representation of Monomer–Excimer Kinetics: General Results and Application to Pyrene. J Phys Chem B 2015; 119:15023-9. [DOI: 10.1021/acs.jpcb.5b08875] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Liliana Martelo
- CQFM - Centro de Química-Física
Molecular and IN - Institute of Nanoscience and Nanotechnology, Instituto
Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Alexander Fedorov
- CQFM - Centro de Química-Física
Molecular and IN - Institute of Nanoscience and Nanotechnology, Instituto
Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Mário N. Berberan-Santos
- CQFM - Centro de Química-Física
Molecular and IN - Institute of Nanoscience and Nanotechnology, Instituto
Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| |
Collapse
|
27
|
Thompson AJ, Herling TW, Kubánková M, Vyšniauskas A, Knowles TPJ, Kuimova MK. Molecular Rotors Provide Insights into Microscopic Structural Changes During Protein Aggregation. J Phys Chem B 2015; 119:10170-9. [DOI: 10.1021/acs.jpcb.5b05099] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Therese W. Herling
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Markéta Kubánková
- Chemistry
Department, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Aurimas Vyšniauskas
- Chemistry
Department, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Tuomas P. J. Knowles
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Marina K. Kuimova
- Chemistry
Department, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| |
Collapse
|
28
|
Martelo L, Fedorov A, Berberan-Santos MN. Fluorescence Phasor Plots Using Time Domain Data: Effect of the Instrument Response Function. J Phys Chem B 2015; 119:10267-74. [PMID: 26182386 DOI: 10.1021/acs.jpcb.5b00261] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phasor plots of the fluorescence intensity decay (plots of the Fourier sine transform vs the Fourier cosine transform, for one or several angular frequencies) are being increasingly used, namely, in fluorescence lifetime imaging microscopy (FLIM) of cells, tissues, and surfaces, but are also relevant for the characterization of homogeneous (e.g., solution) systems. In this work, the construction of the phasor plot using time domain data is discussed, including the effect of the instrument response function (IRF). A deconvolution method in the Fourier space is described. The results obtained are applied to fluorescence decays of aqueous fluorescein (basic form) in the presence of concentrated potassium iodide. The effect of the impulse is clearly shown, in accordance with model predictions. Deconvolution in the Fourier space works well for lifetimes at least 1 order of magnitude higher than the IRF time width.
Collapse
Affiliation(s)
- Liliana Martelo
- CQFM - Centro de Química-Física Molecular and IN - Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Alexander Fedorov
- CQFM - Centro de Química-Física Molecular and IN - Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Mário N Berberan-Santos
- CQFM - Centro de Química-Física Molecular and IN - Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| |
Collapse
|
29
|
Lopes JLS, Araujo APU, Jameson DM. Investigation of the conformational flexibility of DGAT1 peptides using tryptophan fluorescence. Methods Appl Fluoresc 2015; 3:025003. [PMID: 29148488 DOI: 10.1088/2050-6120/3/2/025003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The conformational behavior of synthetic peptides corresponding to the putative binding sites of the diacylglycerol acyltransferase 1 enzyme (a polytopic integral membrane protein) was investigated using steady-state and time-resolved fluorescence spectroscopies. Three small linear peptides with 13, 15 and 22 amino acid residues, containing one, two and three Trp residues, respectively, were studied in aqueous solution, in the absence and presence of model membranes. The high flexibility and unordered conformation of the peptides in solution were confirmed by the low Trp polarization values, the high accessibility to water-soluble quencher, and the fast rotational correlation times of the Trp residues. However, upon binding to the lipid systems, the Trp residues were incorporated within the acyl hydrophobic core and their lifetimes and rotational correlation times increased. Phasor plots were employed to analyze intensity decay of peptide-lipid binding and provided a trajectory, in phasor space, that lies along a line connecting the points of the free and bound peptide. This trajectory was analyzed to determine the association constant of the peptide to the model membrane.
Collapse
Affiliation(s)
- Jose L S Lopes
- Institute of Physics of Sao Carlos, University of Sao Paulo, Sao Carlos, SP, Brazil. Department of Cell and Molecular Biology, University of Hawaii at Manoa, Honolulu, HI, USA
| | | | | |
Collapse
|
30
|
|
31
|
Application of ANS fluorescent probes to identify hydrophobic sites on the surface of DREAM. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1472-80. [PMID: 24854592 DOI: 10.1016/j.bbapap.2014.05.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/01/2014] [Accepted: 05/12/2014] [Indexed: 11/23/2022]
Abstract
DREAM (calsenilin or KChIP-3) is a calcium sensor involved in regulation of diverse physiological processes by interactions with multiple intracellular partners including DNA, Kv4 channels, and presenilin, however the detailed mechanism of the recognition of the intracellular partners remains unclear. To identify the surface hydrophobic surfaces on apo and Ca(2+)DREAM as a possible interaction sites for target proteins and/or specific regulators of DREAM function the binding interactions of 1,8-ANS and 2,6-ANS with DREAM were characterized by fluorescence and docking studies. Emission intensity of ANS-DREAM complexes increases upon Ca(2+) association which is consistent with an overall decrease in surface polarity. The dissociation constants for ANS binding to apoDREAM and Ca(2+)DREAM were determined to be 195±20μM and 62±4μM, respectively. Fluorescence lifetime measurements indicate that two ANS molecules bind in two independent binding sites on DREAM monomer. One site is near the exiting helix of EF-4 and the second site is located in the hydrophobic crevice between EF-3 and EF-4. 1,8-ANS displacement studies using arachidonic acid demonstrate that the hydrophobic crevice between EF-3 and EF-4 serves as a binding site for fatty acids that modulate functional properties of Kv4 channel:KChIP complexes. Thus, the C-terminal hydrophobic crevice may be involved in DREAM interactions with small hydrophobic ligands as well as other intracellular proteins.
Collapse
|
32
|
Montecinos-Franjola F, James NG, Concha-Marambio L, Brunet JE, Lagos R, Monasterio O, Jameson DM. Single tryptophan mutants of FtsZ: nucleotide binding/exchange and conformational transitions. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1193-200. [PMID: 24704635 DOI: 10.1016/j.bbapap.2014.03.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 03/24/2014] [Accepted: 03/26/2014] [Indexed: 11/27/2022]
Abstract
Cell division protein FtsZ cooperatively self-assembles into straight filaments when bound to GTP. A set of conformational changes that are linked to FtsZ GTPase activity are involved in the transition from straight to curved filaments that eventually disassemble. In this work, we characterized the fluorescence of single Trp mutants as a reporter of the predicted conformational changes between the GDP- and GTP-states of Escherichia coli FtsZ. Steady-state fluorescence characterization showed the Trp senses different environments and displays low solvent accessibility. Time-resolved fluorescence data indicated that the main conformational changes in FtsZ occur at the interaction surface between the N and C domains, but also minor rearrangements were detected in the bulk of the N domain. Surprisingly, despite its location near the bottom protofilament interface at the C domain, the Trp 275 fluorescence lifetime did not report changes between the GDP and GTP states. The equilibrium unfolding of FtsZ features an intermediate that is stabilized by the nucleotide bound in the N-domain as well as by quaternary protein-protein interactions. In this context, we characterized the unfolding of the Trp mutants using time-resolved fluorescence and phasor plot analysis. A novel picture of the structural transition from the native state in the absence of denaturant, to the solvent-exposed unfolded state is presented. Taken together our results show that conformational changes between the GDP and GTP states of FtsZ, such as those observed in FtsZ unfolding, are restricted to the interaction surface between the N and C domains.
Collapse
Affiliation(s)
- Felipe Montecinos-Franjola
- Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800024, Chile.
| | - Nicholas G James
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu 96813, HI, USA.
| | - Luis Concha-Marambio
- Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800024, Chile.
| | - Juan E Brunet
- Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso 2373223, Chile.
| | - Rosalba Lagos
- Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800024, Chile.
| | - Octavio Monasterio
- Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800024, Chile.
| | - David M Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu 96813, HI, USA.
| |
Collapse
|
33
|
Abstract
Frequency domain fluorometry is a widely utilized tool in the physical, chemical, and biological sciences. This chapter focuses on the theory of the method and the practical aspects required to carry out intensity decay, i.e., lifetime measurements on a modern frequency domain fluorometer. Several chemical/biological systems are utilized to illustrate data acquisition protocols. Data analysis procedures and methodologies are also discussed.
Collapse
Affiliation(s)
- Carissa M Vetromile
- Department Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | | |
Collapse
|
34
|
Chiu CL, Gratton E. Axial super resolution topography of focal adhesion by confocal microscopy. Microsc Res Tech 2013; 76:1070-8. [PMID: 23897846 DOI: 10.1002/jemt.22267] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 07/07/2013] [Indexed: 11/07/2022]
Abstract
The protein organization within focal adhesions has been studied by state-of-the-art super resolution methods because of its thin structure, well below diffraction limit. However, to achieve high axial resolution, most of the current approaches rely on either sophisticated optics or diligent sample preparation, limiting their application. In this report we present a phasor-based method that can be applied to fluorescent samples to determine the precise axial position of proteins using a conventional confocal microscope. We demonstrate that with about 4,000 photon counts collected along a z-scan, axial localization precision close to 10 nm is achievable. We show that, with within 10 nm, the axial location of paxillin, FAK, and talin is similar at focal adhesion sites, while F-actin shows a sharp increase in height towards the cell center. We further demonstrated the live imaging capability of this method. With the advantage of simple data acquisition and no special instrument requirement, this approach could have wide dissemination and application potentials.
Collapse
Affiliation(s)
- Chi-Li Chiu
- Department of Developmental and Cell Biology, University of California, Irvine, California; Laboratory for Fluorescence Dynamics, University of California, Irvine, California
| | | |
Collapse
|
35
|
Lajevardipour A, Clayton AHA. The effect of translational motion on FLIM measurements-single particle phasor-FLIM. J Fluoresc 2013; 23:671-9. [PMID: 23471622 DOI: 10.1007/s10895-013-1174-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 02/24/2013] [Indexed: 11/25/2022]
Abstract
Fluorescence lifetime imaging microscopy or FLIM provides a versatile tool for spatially-mapping macromolecular interactions and environments through pixel-by-pixel resolution of the excited-state lifetime. In conventional frequency-domain FLIM the phase and modulation of the detected fluorescence are determined by the photophysics of the fluorophore only. However, translational motion on the timescale of FLIM acquisition can significantly perturb apparent phase and modulation values owing to intensity fluctuations and phase decoherence. Using the phasor plot we outline a simple analytic theory, numerical simulations and measurements on fluorescent beads (ex 470 nm, em 520 nm). Fluctuations due to particle motions result in an increase in the number and spread of phasors, an effect we refer to as phasor broadening. The approach paves the way for the measurement of lifetimes and translational motion from one experiment.
Collapse
Affiliation(s)
- Alireza Lajevardipour
- Centre for Micro-photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, John Street, PO Box 218, Hawthorn, Victoria, 3122, Australia
| | | |
Collapse
|
36
|
Jameson DM, Vetromile CM, James NG. Investigations of protein–protein interactions using time-resolved fluorescence and phasors. Methods 2013; 59:278-86. [DOI: 10.1016/j.ymeth.2013.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 01/10/2013] [Accepted: 01/11/2013] [Indexed: 11/28/2022] Open
|
37
|
Buscaglia R, Jameson DM, Chaires JB. G-quadruplex structure and stability illuminated by 2-aminopurine phasor plots. Nucleic Acids Res 2012; 40:4203-15. [PMID: 22241767 PMCID: PMC3351194 DOI: 10.1093/nar/gkr1286] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/13/2011] [Accepted: 12/15/2011] [Indexed: 11/17/2022] Open
Abstract
The use of time-resolved fluorescence measurements in studies of telomeric G-quadruplex folding and stability has been hampered by the complexity of fluorescence lifetime distributions in solution. The application of phasor diagrams to the analysis of time-resolved fluorescence measurements, collected from either frequency-domain or time-domain instrumentation, allows for rapid characterization of complex lifetime distributions. Phasor diagrams are model-free graphical representations of transformed time-resolved fluorescence results. Simplification of complex fluorescent decays by phasor diagrams is demonstrated here using a 2-aminopurine substituted telomeric G-quadruplex sequence. The application of phasor diagrams to complex systems is discussed with comparisons to traditional non-linear regression model fitting. Phasor diagrams allow for the folding and stability of the telomeric G-quadruplex to be monitored in the presence of either sodium or potassium. Fluorescence lifetime measurements revealed multiple transitions upon folding of the telomeric G-quadruplex through the addition of potassium. Enzymatic digestion of the telomeric G-quadruplex structure, fluorescence quenching and Förster resonance energy transfer were also monitored through phasor diagrams. This work demonstrates the sensitivity of time-resolved methods for monitoring changes to the telomeric G-quadruplex and outlines the phasor diagram approach for analysis of complex time-resolved results that can be extended to other G-quadruplex and nucleic acid systems.
Collapse
Affiliation(s)
- Robert Buscaglia
- James Graham Brown Cancer Center, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202 and Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA
| | - David M. Jameson
- James Graham Brown Cancer Center, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202 and Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA
| | - Jonathan B. Chaires
- James Graham Brown Cancer Center, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202 and Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA
| |
Collapse
|
38
|
Sanchez S, Bakás L, Gratton E, Herlax V. Alpha hemolysin induces an increase of erythrocytes calcium: a FLIM 2-photon phasor analysis approach. PLoS One 2011; 6:e21127. [PMID: 21698153 PMCID: PMC3116868 DOI: 10.1371/journal.pone.0021127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 05/19/2011] [Indexed: 12/26/2022] Open
Abstract
α-Hemolysin (HlyA) from Escherichia coli is considered as the prototype of a family of toxins called RTX (repeat in toxin), a group of proteins that share genetic and structural features. HlyA is an important virulence factor in E. coli extraintestinal infections, such as meningitis, septicemia and urinary infections. High concentrations of the toxin cause the lysis of several cells such as erythrocytes, granulocytes, monocytes, endothelial and renal epithelial cells of different species. At low concentrations it induces the production of cytokines and apoptosis. Since many of the subcytolytic effects in other cells have been reported to be triggered by the increase of intracellular calcium, we followed the calcium concentration inside the erythrocytes while incubating with sublytic concentrations of HlyA. Calcium concentration was monitored using the calcium indicator Green 1, 2-photon excitation, and fluorescence lifetime imaging microscopy (FLIM). Data were analyzed using the phasor representation. In this report, we present evidence that, at sublytic concentrations, HlyA induces an increase of calcium concentration in rabbit erythrocytes in the first 10 s. Results are discussed in relation to the difficulties of measuring calcium concentrations in erythrocytes where hemoglobin is present, the contribution of the background and the heterogeneity of the response observed in individual cells.
Collapse
Affiliation(s)
- Susana Sanchez
- Laboratory for Fluorescence Dynamics, University of California Irvine, Irvine, California, United States of America
- Microscopy Unit, Fundación CNIC-Carlos III, Centro Nacional de Investigaciones Cardiovasculares, Madrid, España
| | - Laura Bakás
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
- Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, University of California Irvine, Irvine, California, United States of America
| | - Vanesa Herlax
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| |
Collapse
|