1
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Shi T, Liu T, Zhang J, Cai D, Zhang Y. A test strip constructed by molecular imprinting for ratiometric fluorescence with ultra-low limit of detection for selective monitoring of Sudan I in chili powder. Mikrochim Acta 2023; 190:263. [PMID: 37332000 DOI: 10.1007/s00604-023-05825-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 05/04/2023] [Indexed: 06/20/2023]
Abstract
An up-conversion molecularly imprinted ratiometric fluorescent probe with a monodisperse nuclear-satellite structure and its test strip are designed which can avoid fluorescent background interference to detect Sudan I in chili powder highly selective and sensitive. The detection mechanism is based on the selective recognition of Sudan I by imprinted cavities on the surface of ratiometric fluorescent probe and the inner filter effect between Sudan I molecules and the emission of up-conversion materials (NaYF4:Yb,Tm). Under optimized experimental conditions, the response of fluorescent ratio signals (F475/F645) of this test strip show a good linear relationship in the range 0.02-50 μM Sudan I. The limits of detection and quantitation are as low as 6 nM and 20 nM, respectively. Sudan I is selectively detected in the presence of fivefold higher concentrations of interfering substances (imprinting factor up to 4.4). Detection of Sudan I in chili powder samples show ultra-low LOD (44.7 ng/g), satisfactory recoveries (94.99-105.5%) and low relative standard deviation (≤ 2.0%). This research offers a reliable strategy and promising scheme for highly selective and sensitive detection of illegal additives in complex food matrix via an up-conversion molecularly imprinted ratiometric fluorescent test strip.
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Affiliation(s)
- Tian Shi
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Tong Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Jinyuan Zhang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Da Cai
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Yueli Zhang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China.
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2
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Sauge-Merle S, Recuerda M, Beccia MR, Lemaire D, Cherif R, Bremond N, Merola F, Bousmah Y, Berthomieu C. Development of an Efficient FRET-Based Ratiometric Uranium Biosensor. BIOSENSORS 2023; 13:bios13050561. [PMID: 37232922 DOI: 10.3390/bios13050561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/12/2023] [Accepted: 05/15/2023] [Indexed: 05/27/2023]
Abstract
The dispersion of uranium in the environment can pose a problem for the health of humans and other living organisms. It is therefore important to monitor the bioavailable and hence toxic fraction of uranium in the environment, but no efficient measurement methods exist for this. Our study aims to fill this gap by developing a genetically encoded FRET-based ratiometric uranium biosensor. This biosensor was constructed by grafting two fluorescent proteins to both ends of calmodulin, a protein that binds four calcium ions. By modifying the metal-binding sites and the fluorescent proteins, several versions of the biosensor were generated and characterized in vitro. The best combination results in a biosensor that is affine and selective for uranium compared to metals such as calcium or other environmental compounds (sodium, magnesium, chlorine). It has a good dynamic range and should be robust to environmental conditions. In addition, its detection limit is below the uranium limit concentration in drinking water defined by the World Health Organization. This genetically encoded biosensor is a promising tool to develop a uranium whole-cell biosensor. This would make it possible to monitor the bioavailable fraction of uranium in the environment, even in calcium-rich waters.
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Affiliation(s)
- Sandrine Sauge-Merle
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, 13108 Saint Paul-Lez-Durance, France
| | - Morgane Recuerda
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, 13108 Saint Paul-Lez-Durance, France
| | - Maria Rosa Beccia
- Université Côte d'Azur, CNRS, Institut de Chimie de Nice, UMR 7272, 06108 Nice, France
| | - David Lemaire
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, 13108 Saint Paul-Lez-Durance, France
| | - Rym Cherif
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, 13108 Saint Paul-Lez-Durance, France
| | - Nicolas Bremond
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, 13108 Saint Paul-Lez-Durance, France
| | - Fabienne Merola
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, 91405 Orsay, France
| | - Yasmina Bousmah
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, 91405 Orsay, France
| | - Catherine Berthomieu
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, 13108 Saint Paul-Lez-Durance, France
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3
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Díaz Vázquez G, Cui Q, Senes A. Thermodynamic analysis of the GAS right transmembrane motif supports energetic model of dimerization. Biophys J 2023; 122:143-155. [PMID: 36371634 PMCID: PMC9822795 DOI: 10.1016/j.bpj.2022.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/12/2022] [Accepted: 11/09/2022] [Indexed: 11/13/2022] Open
Abstract
The GASright motif, best known as the fold of the glycophorin A transmembrane dimer, is one of the most common dimerization motifs in membrane proteins, characterized by its hallmark GxxxG-like sequence motifs (GxxxG, AxxxG, GxxxS, and similar). Structurally, GASright displays a right-handed crossing angle and short interhelical distance. Contact between the helical backbones favors the formation of networks of weak hydrogen bonds between Cα-H carbon donors and carbonyl acceptors on opposing helices (Cα-H···O=C). To understand the factors that modulate the stability of GASright, we previously presented a computational and experimental structure-based analysis of 26 predicted dimers. We found that the contributions of van der Waals packing and Cα-H hydrogen bonding to stability, as inferred from the structural models, correlated well with relative dimerization propensities estimated experimentally with the in vivo assay TOXCAT. Here we test this model with a quantitative thermodynamic analysis. We used Förster resonance energy transfer (FRET) to determine the free energy of dimerization of a representative subset of seven of the 26 original TOXCAT dimers using FRET. To overcome the technical issue arising from limited sampling of the dimerization isotherm, we introduced a globally fitting strategy across a set of constructs comprising a wide range of stabilities. This strategy yielded precise thermodynamic data that show strikingly good agreement between the original propensities and ΔG° of association in detergent, suggesting that TOXCAT is a thermodynamically driven process. From the correlation between TOXCAT and thermodynamic stability, the predicted free energy for all the 26 GASright dimers was calculated. These energies correlate with the in silico ΔE scores of dimerization that were computed on the basis of their predicted structure. These findings corroborate our original model with quantitative thermodynamic evidence, strengthening the hypothesis that van der Waals and Cα-H hydrogen bond interactions are the key modulators of GASright stability.
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Affiliation(s)
- Gladys Díaz Vázquez
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin; Biophysics Graduate Program, University of Wisconsin-Madison, Madison, Wisconsin
| | - Qiang Cui
- Department of Chemistry, Boston University, Boston, Massachusetts
| | - Alessandro Senes
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin.
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4
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Rani K, Sengupta S. Multi-stimuli programmable FRET based RGB absorbing antennae towards ratiometric temperature, pH and multiple metal ion sensing. Chem Sci 2021; 12:15533-15542. [PMID: 35003582 PMCID: PMC8654024 DOI: 10.1039/d1sc05112a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 11/15/2021] [Indexed: 01/03/2023] Open
Abstract
A red-green-blue (RGB) multichromophoric antenna 1 consisting of energy donors naphthalimides and perylenediimides and a central aza-BODIPY energy acceptor along with two subchromophoric red-blue (RB 6) and green-blue (GB 12) antennae was designed that showed efficient cascade Förster resonance energy transfer (FRET). RGB antenna 1 showed pronounced temperature-dependent emission behaviour where emission intensities in green and red channels could be tuned in opposite directions by temperature giving rise to unique ratiometric sensing with a temperature sensitivity of 0.4% °C. RGB antenna 1 showed reversible absorption modulation selectively in the blue region (RGB ↔ RG) upon acid/base addition giving rise to pH sensing behaviour. Furthermore, RGB antenna 1 was utilized to selectively sense metal ions such as Co2+ and Fe3+ through a FRET turn-off mechanism induced by a redox process at the aza-BODIPY site that resulted in the selective spectral modulation of the red band (i.e., RGB → GB). Model antenna RB 6 showed white light emission with chromaticity coordinates (0.32, 0.33) on acid addition. Antennae 1, 6 and 12 also exhibited solution state electrochromic switching characterized by distinct colour changes upon changing the potential. Finally, antennae 1, 6 and 12 served as reversible fluorescent inks in PMMA/antenna blends whereby the emission colours could be switched or tuned using different stimuli such as acid vapour, temperature and metal ions.
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Affiliation(s)
- Kavita Rani
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali Punjab-140306 India
| | - Sanchita Sengupta
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali Punjab-140306 India
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5
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Kowada T, Mizukami S. Fluorescent Probes for the Quantification of Labile Metal Ions in Living Cells. J SYN ORG CHEM JPN 2021. [DOI: 10.5059/yukigoseikyokaishi.79.1020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Shin Mizukami
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
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6
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Tian L, Guo H, Li J, Yan L, Zhu E, Liu X, Li K. Fabrication of a near-infrared excitation surface molecular imprinting ratiometric fluorescent probe for sensitive and rapid detecting perfluorooctane sulfonate in complex matrix. JOURNAL OF HAZARDOUS MATERIALS 2021; 413:125353. [PMID: 33609881 DOI: 10.1016/j.jhazmat.2021.125353] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 02/02/2021] [Accepted: 02/05/2021] [Indexed: 05/29/2023]
Abstract
Construction of fluorescent probe for highly sensitive and selective detection of perfluorooctane sulfonate (PFOS) in water and biological samples is a very important strategy in related pollutant monitoring and environmental health risk appraisal. To overcome the drawback of low sensitivity caused by high-back ground signal of the conventional sensor, a molecularly imprinted near-infrared excitation ratiometric fluorescent probe was constructed and employed to determine PFOS. The sensing process was achieved through the selectively recognition of specific cavities in the probe surface with analyte, accompanied by fluorescence quenching due to the photoinduced electron transfer effect between upconversion materials and PFOS. Under optimized experimental conditions, the fluorescence quenching efficiency of the probe has good linearity against the concentrations of PFOS response divided into two segments within linear ranges of 0.001-0.1 nmol/L and 0.1-1 nmol/L, respectively, with low detection limit of 1 pmol/L. Selective experiment results indicate that the C-F chain length plays a dominant role in molecular recognition and high sensitively detection. The fabricated probe shows well detection performance in a wide pH range. Furthermore, real samples analyses indicate that such an efficient fluorescent probe has potentials in PFOS determination in surface water, human serum and egg extract sample analyses.
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Affiliation(s)
- Lingxi Tian
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, School of Environmental and Chemical Engineering, Nanchang HangKong University, Nanchang 330063, China
| | - Huiqin Guo
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, School of Environmental and Chemical Engineering, Nanchang HangKong University, Nanchang 330063, China.
| | - Jing Li
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, School of Environmental and Chemical Engineering, Nanchang HangKong University, Nanchang 330063, China
| | - Liushui Yan
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, School of Environmental and Chemical Engineering, Nanchang HangKong University, Nanchang 330063, China.
| | - Enze Zhu
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, School of Environmental and Chemical Engineering, Nanchang HangKong University, Nanchang 330063, China
| | - Xiaoming Liu
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, School of Environmental and Chemical Engineering, Nanchang HangKong University, Nanchang 330063, China
| | - Kexin Li
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, School of Environmental and Chemical Engineering, Nanchang HangKong University, Nanchang 330063, China
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7
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Kowada T, Watanabe T, Amagai Y, Liu R, Yamada M, Takahashi H, Matsui T, Inaba K, Mizukami S. Quantitative Imaging of Labile Zn 2+ in the Golgi Apparatus Using a Localizable Small-Molecule Fluorescent Probe. Cell Chem Biol 2020; 27:1521-1531.e8. [PMID: 32997976 DOI: 10.1016/j.chembiol.2020.09.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 06/16/2020] [Accepted: 09/08/2020] [Indexed: 12/15/2022]
Abstract
Fluorescent Zn2+ probes used for the quantitative analysis of labile Zn2+ concentration ([Zn2+]) in target organelles are crucial for understanding the role of Zn2+ in biological processes. Although several fluorescent Zn2+ probes have been developed to date, there is still a lack of consensus concerning the [Zn2+] in intracellular organelles. In this study, we describe the development of ZnDA-1H, a small-molecule fluorescent probe for Zn2+, which exhibits less pH sensitivity, high Zn2+ selectivity, and large fluorescence enhancement upon binding to Zn2+. Through protein labeling technology, ZnDA-1H was precisely targeted in various intracellular organelles, such as the nucleus, mitochondria, endoplasmic reticulum, and Golgi apparatus. ZnDA-1H exhibited a reversible fluorescence response toward labile Zn2+ in these organelles in live cells. Using this probe, the [Zn2+] in the Golgi apparatus was estimated to be 25 ± 1 nM, suggesting that labile Zn2+ plays a physiological role in the secretory pathway.
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Affiliation(s)
- Toshiyuki Kowada
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Tomomi Watanabe
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Yuta Amagai
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Rong Liu
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Momo Yamada
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Hiroto Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Toshitaka Matsui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Shin Mizukami
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan.
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8
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Wetzler DE, Fuchs Wightman F, Bucci HA, Rinaldi J, Caramelo JJ, Iusem ND, Ricardi MM. Conformational plasticity of the intrinsically disordered protein ASR1 modulates its function as a drought stress-responsive gene. PLoS One 2018; 13:e0202808. [PMID: 30138481 PMCID: PMC6107238 DOI: 10.1371/journal.pone.0202808] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 08/09/2018] [Indexed: 11/18/2022] Open
Abstract
Plants in arid zones are constantly exposed to drought stress. The ASR protein family (Abscisic, Stress, Ripening) -a subgroup of the late embryogenesis abundant superfamily- is involved in the water stress response and adaptation to dry environments. Tomato ASR1, as well as other members of this family, is an intrinsically disordered protein (IDP) that functions as a transcription factor and a chaperone. Here we employed different biophysical techniques to perform a deep in vitro characterization of ASR1 as an IDP and showed how both environmental factors and in vivo targets modulate its folding. We report that ASR1 adopts different conformations such as α-helix or polyproline type II in response to environmental changes. Low temperatures and low pH promote the polyproline type II conformation (PII). While NaCl increases PII content and slightly destabilizes α-helix conformation, PEG and glycerol have an important stabilizing effect of α-helix conformation. The binding of Zn2+in the low micromolar range promotes α-helix folding, while extra Zn2+ results in homo-dimerization. The ASR1-DNA binding is sequence specific and dependent on Zn2+. ASR1 chaperone activity does not change upon the structure induction triggered by the addition of Zn2+. Furthermore, trehalose, which has no effect on the ASR1 structure by itself, showed a synergistic effect on the ASR1-driven heat shock protection towards the reporter enzyme citrate synthase (CS). These observations prompted the development of a FRET reporter to sense ASR1 folding in vivo. Its performance was confirmed in Escherichia coli under saline and osmotic stress conditions, representing a promising probe to be used in plant cells. Overall, this work supports the notion that ASR1 plasticity is a key feature that facilitates its response to drought stress and its interaction with specific targets.
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Affiliation(s)
- Diana E. Wetzler
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
- * E-mail: (DW); (MR)
| | - Federico Fuchs Wightman
- Departamento de Fisiología y Biología Molecular y Celular (FBMC), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Hernan A. Bucci
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Jimena Rinaldi
- Fundación Instituto Leloir, Buenos Aires, Argentina e Instituto de investigaciones Bioquímicas de Buenos Aires (IIBBA- CONICET), Buenos Aires, Argentina
| | - Julio J. Caramelo
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Fundación Instituto Leloir, Buenos Aires, Argentina e Instituto de investigaciones Bioquímicas de Buenos Aires (IIBBA- CONICET), Buenos Aires, Argentina
| | - Norberto D. Iusem
- Departamento de Fisiología y Biología Molecular y Celular (FBMC), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Martiniano M. Ricardi
- Departamento de Fisiología y Biología Molecular y Celular (FBMC), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
- * E-mail: (DW); (MR)
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9
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Carter KP, Carpenter MC, Fiedler B, Jimenez R, Palmer AE. Critical Comparison of FRET-Sensor Functionality in the Cytosol and Endoplasmic Reticulum and Implications for Quantification of Ions. Anal Chem 2017; 89:9601-9608. [PMID: 28758723 DOI: 10.1021/acs.analchem.7b02933] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Genetically encoded sensors based on fluorescence resonance energy transfer (FRET) are powerful tools for quantifying and visualizing analytes in living cells, and when targeted to organelles have the potential to define distribution of analytes in different parts of the cell. However, quantitative estimates of analyte distribution require rigorous and systematic analysis of sensor functionality in different locations. In this work, we establish methods to critically evaluate sensor performance in different organelles and carry out a side-by-side comparison of three different genetically encoded sensor platforms for quantifying cellular zinc ions (Zn2+). Calibration conditions are optimized for high dynamic range and stable FRET signals. Using a combination of single-cell microscopy and a novel microfluidic platform capable of screening thousands of cells in a few hours, we observe differential performance of these sensors in the cytosol compared to the ER of HeLa cells, and identify the formation of oxidative oligomers of the sensors in the ER. Finally, we use new methodology to re-evaluate the binding parameters of these sensors both in the test tube and in living cells. Ultimately, we demonstrate that sensor responses can be affected by different cellular environments, and provide a framework for evaluating future generations of organelle-targeted sensors.
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Affiliation(s)
- Kyle P Carter
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,BioFrontiers Institute, University of Colorado , Boulder, Colorado 80303, United States
| | - Margaret C Carpenter
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,BioFrontiers Institute, University of Colorado , Boulder, Colorado 80303, United States
| | - Brett Fiedler
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,JILA, University of Colorado and National Institute of Standards and Technology , Boulder, Colorado 80309, United States
| | - Ralph Jimenez
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,JILA, University of Colorado and National Institute of Standards and Technology , Boulder, Colorado 80309, United States
| | - Amy E Palmer
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80303, United States.,BioFrontiers Institute, University of Colorado , Boulder, Colorado 80303, United States
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10
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A Ratiomeric Fluorescent Sensor for Zn 2+ Based on N,N'-Di(quinolin-8-yl)oxalamide. J Fluoresc 2016; 27:723-728. [PMID: 28004345 DOI: 10.1007/s10895-016-2003-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 12/11/2016] [Indexed: 01/27/2023]
Abstract
A new ratiometric fluorescent sensor (DQO) based on N,N'-Di(quinolin-8-yl) oxalamide has been designed and synthesized for selective detection of Zn2+. The fluorescence ratio (I 536 nm/I 450 nm) of DQO was enhanced 10-fold when Zn2+ was present in a buffer aqueous solution at pH 8.66. The sensor showed linear response toward Zn2+ in the concentration range 0-15 μM, and the detection limit was calculated to be 2.4 μM. A Job's plot implied the formation of a DQO/Zn2+ complex with 1:1 stoichiometry, and the apparent association constant of DQO/Zn2+ complex was computed to be 1.5 × 104 M-1.
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11
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Abstract
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Genetically encoded
FRET-based sensor proteins have significantly
contributed to our current understanding of the intracellular functions
of Zn2+. However, the external excitation required for
these fluorescent sensors can give rise to photobleaching and phototoxicity
during long-term imaging, limits applications that suffer from autofluorescence
and light scattering, and is not compatible with light-sensitive cells.
For these applications, sensor proteins based on Bioluminescence Resonance
Energy Transfer (BRET) would provide an attractive alternative. In
this work, we used the bright and stable luciferase NanoLuc to create
the first genetically encoded BRET sensors for measuring intracellular
Zn2+. Using a new sensor approach, the NanoLuc domain was
fused to the Cerulean donor domain of two previously developed FRET
sensors, eCALWY and eZinCh-2. In addition to preserving the excellent
Zn2+ affinity and specificity of their predecessors, these
newly developed sensors enable both BRET- and FRET-based detection.
While the dynamic range of the BRET signal for the eCALWY-based BLCALWY-1
sensor was limited by the presence of two competing BRET pathways,
BRET/FRET sensors based on the eZinCh-2 scaffold (BLZinCh-1 and -2)
yielded robust 25–30% changes in BRET ratio. In addition, introduction
of a chromophore-silencing mutation resulted in a BRET-only sensor
(BLZinCh-3) with increased BRET response (50%) and an unexpected 10-fold
increase in Zn2+ affinity. The combination of robust ratiometric
response, physiologically relevant Zn2+ affinities, and
stable and bright luminescence signal offered by the BLZinCh sensors
allowed monitoring of intracellular Zn2+ in plate-based
assays as well as intracellular BRET-based imaging in single living
cells in real time.
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Affiliation(s)
- Stijn J. A. Aper
- Laboratory
of Chemical Biology and Institute for Complex Molecular Systems (ICMS),
Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Pieterjan Dierickx
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
- Division
of Heart and Lungs, Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Maarten Merkx
- Laboratory
of Chemical Biology and Institute for Complex Molecular Systems (ICMS),
Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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12
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Carpenter MC, Lo MN, Palmer AE. Techniques for measuring cellular zinc. Arch Biochem Biophys 2016; 611:20-29. [PMID: 27580940 DOI: 10.1016/j.abb.2016.08.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 08/19/2016] [Accepted: 08/23/2016] [Indexed: 02/08/2023]
Abstract
The development and improvement of fluorescent Zn2+ sensors and Zn2+ imaging techniques have increased our insight into this biologically important ion. Application of these tools has identified an intracellular labile Zn2+ pool and cultivated further interest in defining the distribution and dynamics of labile Zn2+. The study of Zn2+ in live cells in real time using sensors is a powerful way to answer complex biological questions. In this review, we highlight newly engineered Zn2+ sensors, methods to test whether the sensors are accessing labile Zn2+, and recent studies that point to the challenges of using such sensors. Elemental mapping techniques can complement and strengthen data collected with sensors. Both mass spectrometry-based and X-ray fluorescence-based techniques yield highly specific, sensitive, and spatially resolved snapshots of metal distribution in cells. The study of Zn2+ has already led to new insight into all phases of life from fertilization of the egg to life-threatening cancers. In order to continue building new knowledge about Zn2+ biology it remains important to critically assess the available toolset for this endeavor.
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Affiliation(s)
- Margaret C Carpenter
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, United States.
| | - Maria N Lo
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, United States.
| | - Amy E Palmer
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, United States.
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