1
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Jensen GC, Janis MK, Nguyen HN, David OW, Zastrow ML. Fluorescent Protein-Based Sensors for Detecting Essential Metal Ions across the Tree of Life. ACS Sens 2024; 9:1622-1643. [PMID: 38587931 PMCID: PMC11073808 DOI: 10.1021/acssensors.3c02695] [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: 04/10/2024]
Abstract
Genetically encoded fluorescent metal ion sensors are powerful tools for elucidating metal dynamics in living systems. Over the last 25 years since the first examples of genetically encoded fluorescent protein-based calcium indicators, this toolbox of probes has expanded to include other essential and non-essential metal ions. Collectively, these tools have illuminated fundamental aspects of metal homeostasis and trafficking that are crucial to fields ranging from neurobiology to human nutrition. Despite these advances, much of the application of metal ion sensors remains limited to mammalian cells and tissues and a limited number of essential metals. Applications beyond mammalian systems and in vivo applications in living organisms have primarily used genetically encoded calcium ion sensors. The aim of this Perspective is to provide, with the support of historical and recent literature, an updated and critical view of the design and use of fluorescent protein-based sensors for detecting essential metal ions in various organisms. We highlight the historical progress and achievements with calcium sensors and discuss more recent advances and opportunities for the detection of other essential metal ions. We also discuss outstanding challenges in the field and directions for future studies, including detecting a wider variety of metal ions, developing and implementing a broader spectral range of sensors for multiplexing experiments, and applying sensors to a wider range of single- and multi-species biological systems.
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Affiliation(s)
- Gary C Jensen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Makena K Janis
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Hazel N Nguyen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Ogonna W David
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Melissa L Zastrow
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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2
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Veit S, Paweletz LC, Günther Pomorski T. Determination of membrane protein orientation upon liposomal reconstitution down to the single vesicle level. Biol Chem 2023; 404:647-661. [PMID: 36857289 DOI: 10.1515/hsz-2022-0325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 02/07/2023] [Indexed: 03/02/2023]
Abstract
Reconstitution of membrane proteins into liposomal membranes represents a key technique in enabling functional analysis under well-defined conditions. In this review, we provide a brief introduction to selected methods that have been developed to determine membrane protein orientation after reconstitution in liposomes, including approaches based on proteolytic digestion with proteases, site-specific labeling, fluorescence quenching and activity assays. In addition, we briefly highlight new strategies based on single vesicle analysis to address the problem of sample heterogeneity.
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Affiliation(s)
- Sarina Veit
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
| | - Laura Charlotte Paweletz
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
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3
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Dare EO, Akinhanmi TF, Aremu JA, Adetunji OR, Bamgbose JT, Vendrell-Criado V, Jiménez MC, Pérez-Ruiz R, Bonardd S, Díaz Díaz D. Dual-mode colorimetric/fluorescent chemosensor for Cu 2+/Zn 2+ and fingerprint imaging based on rhodamine ethylenediamine bis(triazolyl silsesquioxane). Photochem Photobiol Sci 2023:10.1007/s43630-023-00395-4. [PMID: 36922485 DOI: 10.1007/s43630-023-00395-4] [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: 11/25/2022] [Accepted: 02/07/2023] [Indexed: 03/18/2023]
Abstract
A novel dual functional and visual rhodamine ethylenediamine bis(triazolyl silsesquioxane) (RBS) chemosensor was successfully synthesized using "click" chemistry. The results have unambiguously demonstrated that RBS can act in fluorescent and colorimetric sensing of Cu2+ and Zn2+ by their respective coordination with triazole structures and, more importantly, it has also been found that triazole-amide of RBS could turn on chelation-enhanced fluorescence (CHEF) of Cu2+. Remarkably, the addition of Cu2+ triggered an enhanced fluorescent emission by 63.3-fold (ϕF = 0.41), while Zn2+ enhanced it 48.3-fold (ϕF = 0.29) relative to the original RBS (ϕF = 0.006) in acetonitrile (MeCN) solvent. The fluorescent limit of detection for Cu2+ and Zn2+ is similar and fall within 3.0 nM, while under colorimetric sensing the responses were 2.14 × 10-8 and 4.0 × 10-8 mol L-1, respectively. Moreover, the effective sensing profile of RBS and extended applications of RBS-Cu2+ and RBS-Zn2+ for fingerprinting detection and imaging were observed with adequate sensitivity, stability and legibility under the dual visual responses.
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Affiliation(s)
- Enock O Dare
- Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria. .,Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, Regensburg University, Regensburg, Germany.
| | | | - J A Aremu
- Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria
| | - Olayide R Adetunji
- Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria.,Department of Mechanical Engineering, Federal University of Agriculture Abeokuta, Abeokuta, Nigeria
| | - Janet T Bamgbose
- Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria
| | - Victoria Vendrell-Criado
- Departamento de Química, Universitat Politècnica de València, Camino de Vera, s/n, 46022, Valencia, Spain
| | - M Consuelo Jiménez
- Departamento de Química, Universitat Politècnica de València, Camino de Vera, s/n, 46022, Valencia, Spain
| | - Raúl Pérez-Ruiz
- Departamento de Química, Universitat Politècnica de València, Camino de Vera, s/n, 46022, Valencia, Spain
| | - Sebastian Bonardd
- Departamento de Química Orgánica, Universidad de la Laguna, Avda. Astrofísico Francisco Sánchez 3, 38206, La Laguna, Tenerife, Spain.,Instituto Universitario de Bio-Orgánica Antonio González, Universidad de la Laguna, Avda. Astrofísico Francisco Sánchez 2, 38206, La Laguna, Tenerife, Spain
| | - David Díaz Díaz
- Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, Regensburg University, Regensburg, Germany. .,Departamento de Química Orgánica, Universidad de la Laguna, Avda. Astrofísico Francisco Sánchez 3, 38206, La Laguna, Tenerife, Spain. .,Instituto Universitario de Bio-Orgánica Antonio González, Universidad de la Laguna, Avda. Astrofísico Francisco Sánchez 2, 38206, La Laguna, Tenerife, Spain.
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4
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Kumar V, Ozguney B, Vlachou A, Chen Y, Gazit E, Tamamis P. Peptide Self-Assembled Nanocarriers for Cancer Drug Delivery. J Phys Chem B 2023; 127:1857-1871. [PMID: 36812392 PMCID: PMC10848270 DOI: 10.1021/acs.jpcb.2c06751] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 12/24/2022] [Indexed: 02/24/2023]
Abstract
The design of novel cancer drug nanocarriers is critical in the framework of cancer therapeutics. Nanomaterials are gaining increased interest as cancer drug delivery systems. Self-assembling peptides constitute an emerging novel class of highly attractive nanomaterials with highly promising applications in drug delivery, as they can be used to facilitate drug release and/or stability while reducing side effects. Here, we provide a perspective on peptide self-assembled nanocarriers for cancer drug delivery and highlight the aspects of metal coordination, structure stabilization, and cyclization, as well as minimalism. We review particular challenges in nanomedicine design criteria and, finally, provide future perspectives on addressing a portion of the challenges via self-assembling peptide systems. We consider that the intrinsic advantages of such systems, along with the increasing progress in computational and experimental approaches for their study and design, could possibly lead to novel classes of single or multicomponent systems incorporating such materials for cancer drug delivery.
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Affiliation(s)
- Vijay
Bhooshan Kumar
- The
Shmunis School of Biomedicine and Cancer Research, George S. Wise
Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Busra Ozguney
- Artie
McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, United States
| | - Anastasia Vlachou
- Artie
McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, United States
| | - Yu Chen
- The
Shmunis School of Biomedicine and Cancer Research, George S. Wise
Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ehud Gazit
- The
Shmunis School of Biomedicine and Cancer Research, George S. Wise
Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Department
of Materials Science and Engineering, Iby and Aladar Fleischman Faculty
of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
- Sagol
School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Phanourios Tamamis
- Artie
McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, United States
- Department
of Materials Science and Engineering, Texas
A&M University, College
Station, Texas 77843-3003, United States
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5
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Zou W, Nguyen HN, Zastrow ML. Mutant Flavin-Based Fluorescent Protein Sensors for Detecting Intracellular Zinc and Copper in Escherichia coli. ACS Sens 2022; 7:3369-3378. [PMID: 36282086 PMCID: PMC9888404 DOI: 10.1021/acssensors.2c01376] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Flavin-based fluorescent proteins (FbFPs) are a class of fluorescent reporters that undergo oxygen-independent fluorophore incorporation, which is an important advantage over green fluorescent proteins (GFPs) and mFruits. A FbFP derived from Chlamydomonas reinhardtii (CreiLOV) is a promising platform for designing new metal sensors. Some FbFPs are intrinsically quenched by metal ions, but the question of where metals bind and how to tune metal affinity has not been addressed. We used site-directed mutagenesis of CreiLOV to probe a hypothesized copper(II) binding site that led to fluorescence quenching. Most mutations changed the fluorescence quenching level, supporting the proposed site. One key mutation introducing a second cysteine residue in place of asparagine (CreiLOVN41C) significantly altered metal affinity and selectivity, yielding a zinc sensor. The fluorescence intensity and lifetime of CreiLOVN41C were reversibly quenched by Zn2+ ions with a biologically relevant affinity (apparent dissociation constant, Kd, of 1 nM). Copper quenching of CreiLOVN41C was retained but with several orders of magnitude higher affinity than CreiLOV (Kd = 0.066 fM for Cu2+, 5.4 fM for Cu+) and partial reversibility. We also show that CreiLOVN41C is an excellent intensity- and lifetime-based zinc sensor in aerobic and anaerobic live bacterial cells. Zn2+-induced fluorescence quenching is reversible over several cycles in Escherichia coli cell suspensions and can be imaged by fluorescence microscopy. CreiLOVN41C is a novel oxygen-independent metal sensor that significantly expands the current fluorescent protein-based toolbox of metal sensors and will allow for studies of anaerobic and low oxygen systems previously precluded by the use of oxygen-dependent GFPs.
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Affiliation(s)
- Wenping Zou
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Hazel N. Nguyen
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Melissa L. Zastrow
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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6
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Kumar A, Virender, Saini M, Mohan B, Shayoraj, Kamboj M. Colorimetric and Fluorescent Schiff Base Sensors for Trace Detection of Pollutants and Biologically Significant Cations: A Review (2010-2021). Microchem J 2022. [DOI: 10.1016/j.microc.2022.107798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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7
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Metal-Induced Fluorescence Quenching of Photoconvertible Fluorescent Protein DendFP. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092922. [PMID: 35566273 PMCID: PMC9104182 DOI: 10.3390/molecules27092922] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Revised: 04/28/2022] [Accepted: 05/02/2022] [Indexed: 12/29/2022]
Abstract
Sensitive and accurate detection of specific metal ions is important for sensor development and can advance analytical science and support environmental and human medical examinations. Fluorescent proteins (FPs) can be quenched by specific metal ions and spectroscopically show a unique fluorescence-quenching sensitivity, suggesting their potential application as FP-based metal biosensors. Since the characteristics of the fluorescence quenching are difficult to predict, spectroscopic analysis of new FPs is important for the development of FP-based biosensors. Here we reported the spectroscopic and structural analysis of metal-induced fluorescence quenching of the photoconvertible fluorescent protein DendFP. The spectroscopic analysis showed that Fe2+, Fe3+, and Cu2+ significantly reduced the fluorescence emission of DendFP. The metal titration experiments showed that the dissociation constants (Kd) of Fe2+, Fe3+, and Cu2+ for DendFP were 24.59, 41.66, and 137.18 μM, respectively. The tetrameric interface of DendFP, which the metal ions cannot bind to, was analyzed. Structural comparison of the metal-binding sites of DendFP with those of iq-mEmerald and Dronpa suggested that quenchable DendFP has a unique metal-binding site on the β-barrel that does not utilize the histidine pair for metal binding.
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8
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Zhao H, Zastrow ML. Transition Metals Induce Quenching of Monomeric Near-Infrared Fluorescent Proteins. Biochemistry 2022; 61:494-504. [PMID: 35289592 DOI: 10.1021/acs.biochem.1c00705] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transition metals such as zinc and copper are essential in numerous life processes, and both deficiency and toxic overload of these metals are associated with various diseases. Fluorescent metal sensors are powerful tools for studying the roles of metal ions in the physiology and pathology of biological systems. Green fluorescent protein (GFP) and its derivatives are highly utilized for protein-based sensor design, but application to anaerobic systems is limited because these proteins require oxygen to become fluorescent. Bacteriophytochrome-based monomeric near-infrared fluorescent proteins (miRFPs) covalently bind a bilin cofactor, which can be added exogenously for anaerobic cells. miRFPs can also have emission wavelengths extending to >700 nm, which is valuable for imaging applications. Here, we evaluated the suitability of miRFP670 and miRFP709 as platforms for single fluorescent protein metal ion sensors. We found that divalent metal ions like Zn2+, Co2+, Ni2+, and Cu2+ can quench from ∼6-20% (Zn2+, Co2+, and Ni2+) and up to nearly 90% (Cu2+) of the fluorescence intensity of pure miRFPs and have similar impacts in live Escherichia coli cells expressing miRFPs. The presence of a 6× histidine tag for purification influences metal quenching, but significant Cu2+-induced quenching and a picomolar binding affinity are retained in the absence of the His6 tag in both cuvettes and live bacterial cells. By comparing the Cu2+ and Cu+-induced quenching results for miRFP670 and miRFP709 and through examining absorption spectra and previously reported crystal structures, we propose a surface metal binding site near the biliverdin IXα chromophore.
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Affiliation(s)
- Haowen Zhao
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Melissa L Zastrow
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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9
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Low Molecular Weight Probe for Selective Sensing of PH and Cu 2+ Working as Three INHIBIT Based Digital Comparator. J Fluoresc 2022; 32:405-417. [PMID: 34988841 DOI: 10.1007/s10895-021-02856-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/22/2021] [Indexed: 10/19/2022]
Abstract
A novel simple molecular chemosensor 2 was synthesized and examined for pH, cations and anions detection. At pH values higher than 10, probe 2 switches on a green emission where the excited state intramolecular proton transfer (ESIPT) is ceased. Also, the probe absorption spectrum shows a clear pH dependence, and the probe aqueous solution (ethanol/water = 1:2, borate buffer) responds selectively and sensitively through its fluorescence spectrum to the presence of Cu2+. Job's plot gave a 2:1 stoichiometry of Probe-2/Cu2+ complex, which responds to the presence of S2- and H2PO4- in aqueous solution (ethanol/water = 1:2, borate buffer) by its absorption and fluorescence spectra. In addition, probe 2 mimics a digital comparator based on three INHIBIT logic gates by different outputs using HO- and H+ as inputs. Moreover, probe 2 also executes AND and NOT TRANSFER logic gates using Cu2+ and S2- as inputs.
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10
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Yang L, Pandeya A, Li L, Ojo I, Li Z, Wei Y. Transport Across Two Membrane Bilayers in E. coli by Efflux Pumps of Different Dimensions. J Mol Biol 2021; 434:167376. [PMID: 34838522 DOI: 10.1016/j.jmb.2021.167376] [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: 06/30/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 11/30/2022]
Abstract
AcrAB-TolC and CusBAC are two of the most well-studied Resistance-Nodulation-Division (RND) family tripartite efflux pumps in E. coli. AcrAB-TolC is a multidrug efflux system, while CusBAC transports Cu(I), Cu(II) and Ag(I). The RND pump complexes span both the inner membrane (IM) and the outer membrane (OM). The long axis dimension of the fully assembled AcrAB-TolC is ∼3 nm longer than that of CusBAC. To probe if these two efflux systems with different dimensions affect each other when they need to work simultaneously in the same cell, two real-time assays were used to monitor the efflux activities of these two pumps and their impact on each other. The results showed that the presence of AcrAB-TolC substrates accelerated the accumulation of Cu(I) in BW25113 but not in BW25113ΔcusBA or BW25113ΔtolC strains. Similarly, the presence of Ag(I) slowed down the Nile red efflux in the parent strain more significantly than in the CusBA deficient mutant. To further investigate the impact of the OM/IM distance on the function of these tripartite complexes, we experimented with strains lacking the lipoprotein Lpp or containing Lpp mutant of different lengths. Data from efflux/accumulation assays and susceptibility tests revealed that mutation of Lpp resulted in functional deficiency of both AcrAB-TolC and CusBAC. In conclusion, this study demonstrated that when AcrAB-TolC and CusBAC functioned simultaneously, it took the cell a few minutes to adjust. Furthermore, the presence of Lpp of proper length is important to support full efflux activity of transporters spanning both membrane layers in E. coli.
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Affiliation(s)
- Ling Yang
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Ankit Pandeya
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Lan Li
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Isoiza Ojo
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Zhenyu Li
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Yinan Wei
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA.
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11
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An overview of Structured Biosensors for Metal Ions Determination. CHEMOSENSORS 2021. [DOI: 10.3390/chemosensors9110324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The determination of metal ions is important for nutritional and toxicological assessment. Atomic spectrometric techniques are highly efficient for the determination of these species, but the high costs of acquisition and maintenance hinder the application of these techniques. Inexpensive alternatives for metallic element determination are based on dedicated biosensors. These devices mimic biological systems and convert biochemical processes into physical outputs and can be used for the sensitive and selective determination of chemical species such as cations. In this work, an overview of the proposed biosensors for metal ions determination was carried out considering the last 15 years of publications. Statistical data on the applications, response mechanisms, instrumentation designs, applications of nanomaterials, and multielement analysis are herein discussed.
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12
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Trends in the Design of Intensity-Based Optical Fiber Biosensors (2010-2020). BIOSENSORS-BASEL 2021; 11:bios11060197. [PMID: 34203715 PMCID: PMC8232210 DOI: 10.3390/bios11060197] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/08/2021] [Accepted: 06/09/2021] [Indexed: 12/29/2022]
Abstract
There exists an increasing interest in monitoring low concentrations of biochemical species, as they allow the early-stage detection of illnesses or the monitoring of the environment quality. Thus, both companies and research groups are focused on the development of accurate, fast and highly sensitive biosensors. Optical fiber sensors have been widely employed for these purposes because they provide several advantages for their use in point-of-care and real-time applications. In particular, this review is focused on optical fiber biosensors based on luminescence and absorption. Apart from the key parameters that determine the performance of a sensor (limit of detection, sensibility, cross-sensibility, etc.), other features are analyzed, such as the optical fiber dimensions, the sensing set ups and the fiber functionalization. The aim of this review is to have a comprehensive insight of the different aspects that must be taken into account when working with this kind of sensors.
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13
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Jiang SD, sheng Y, Wu XJ, Zhu YL, Li PP. Chromophorylation of a Novel Cyanobacteriochrome GAF Domain from Spirulina and Its Response to Copper Ions. J Microbiol Biotechnol 2021; 31:233-239. [PMID: 33203817 PMCID: PMC9705869 DOI: 10.4014/jmb.2009.09048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 12/15/2022]
Abstract
Cyanobacteriochromes (CBCRs) are phytochrome-related photoreceptor proteins in cyanobacteria and cover a wide spectral range from ultraviolet to far-red. A single GAF domain that they contain can bind bilin(s) autocatalytically via heterologous recombination and then fluoresce, with potential applications as biomarkers and biosensors. Here, we report that a novel red/green CBCR GAF domain, SPI1085g2 from Spirulina subsalsa, covalently binds both phycocyanobilin (PCB) and phycoerythrobilin (PEB). The PCB-binding GAF domain exhibited canonical red/green photoconversion with weak fluorescence emission. However, the PEB-binding GAF domain, SPI1085g2-PEB, exhibited an intense orange fluorescence (λabs.max = 520 nm, λfluor.max = 555 nm), with a fluorescence quantum yield close to 1.0. The fluorescence of SPI1085g2-PEB was selectively and instantaneously quenched by copper ions in a concentration-dependent manner and exhibited reversibility upon treatment with the metal chelator EDTA. This study identified a novel PEB-binding cyanobacteriochrome-based fluorescent protein with the highest quantum yield reported to date and suggests its potential as a biosensor for the rapid detection of copper ions.
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Affiliation(s)
- Su-Dan Jiang
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China
| | - Yi sheng
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China
| | - Xian-Jun Wu
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China,Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing 10037, P.R. China,National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 22100, P.R. China,Corresponding authors X. Wu Phone: +86-158-5052-0507 E-mail:
| | - Yong-Li Zhu
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China,Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing 10037, P.R. China,National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 22100, P.R. China
| | - Ping-Ping Li
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China,Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing 10037, P.R. China,National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 22100, P.R. China,P. Li Phone: +86-25-8542-7210 E-mail:
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14
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Spectroscopic and Structural Analysis of Cu 2+-Induced Fluorescence Quenching of ZsYellow. BIOSENSORS-BASEL 2020; 10:bios10030029. [PMID: 32210006 PMCID: PMC7146301 DOI: 10.3390/bios10030029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/17/2020] [Accepted: 03/19/2020] [Indexed: 11/16/2022]
Abstract
Fluorescent proteins exhibit fluorescence quenching by specific transition metals, suggesting their potential as fluorescent protein-based metal biosensors. Each fluorescent protein exhibits unique spectroscopic properties and mechanisms for fluorescence quenching by metals. Therefore, the metal-induced fluorescence quenching analysis of various new fluorescent proteins would be important step towards the development of such fluorescent protein-based metal biosensors. Here, we first report the spectroscopic and structural analysis of the yellow fluorescent protein ZsYellow, following its metal-induced quenching. Spectroscopic analysis showed that ZsYellow exhibited a high degree of fluorescence quenching by Cu2+. During Cu2+-induced ZsYellow quenching, fluorescence emission was recovered by adding EDTA. The crystal structure of ZsYellow soaked in Cu2+ solution was determined at a 2.6 Å resolution. The electron density map did not indicate the presence of Cu2+ around the chromophore or the β-barrel surface, which resulted in fluorescence quenching without Cu2+ binding to specific site in ZsYellow. Based on these results, we propose the fluorescence quenching to occur in a distance-dependent manner between the metal and the fluorescent protein, when these components get to a closer vicinity at higher metal concentrations. Our results provide useful insights for future development of fluorescent protein-based metal biosensors.
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15
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Sorenson AE, Schaeffer PM. A new bivalent fluorescent fusion protein for differential Cu(II) and Zn(II) ion detection in aqueous solution. Anal Chim Acta 2019; 1101:120-128. [PMID: 32029102 DOI: 10.1016/j.aca.2019.12.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/06/2019] [Accepted: 12/08/2019] [Indexed: 12/15/2022]
Abstract
Simple and easy to engineer metal-sensing molecules that are capable of differentiating metal ions and producing metal-specific signals are highly desirable. Metal ions affect the thermal stability of proteins by increasing or decreasing their resistance to unfolding. This work illustrates a new strategy for designing bivalent fluorescent fusion proteins capable of differentiating metal ions in solution through their distinct effects on a protein's thermal stability. A new dual purpose metal sensor was developed consisting of biotin protein ligase (BirA) from B. pseudomallei (Bp) fused to green fluorescent protein (GFP). When coupled with differential scanning fluorimetry of GFP-tagged proteins (DSF-GTP) for signal-transduction detection, Bp BirA-GFP yields distinct protein unfolding signatures with Zn(II) and Cu(II) ions in aqueous solutions. The limit of detection of the system is ∼1 μM for both metal species. The system can be used in a variety of high-throughput assay formats including for the screening of metal-binding proteins and chelators. Bp BirA-GFP has also the additional benefit of being useful in Cu(II) ion field-testing applications through simple visual observation of a temperature-dependent loss of fluorescence. Bp BirA-GFP is the first example of a 2protein-based dual purpose Cu(II) and Zn(II) ion sensor compatible with two different yet complementary signal-transduction detection systems.
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Affiliation(s)
- A E Sorenson
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD, 4811, Australia
| | - P M Schaeffer
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD, 4811, Australia.
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16
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Özyurt C, Üstükarcı H, Evran S, Telefoncu A. MerR‐fluorescent protein chimera biosensor for fast and sensitive detection of Hg
2+
in drinking water. Biotechnol Appl Biochem 2019; 66:731-737. [DOI: 10.1002/bab.1805] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/12/2019] [Indexed: 12/27/2022]
Affiliation(s)
- Canan Özyurt
- Department of Biochemistry Faculty of Science Ege University Bornova‐Izmir 35100 Turkey
- Department of Chemistry and Chemical Processing Technologies Lapseki Vocational School Canakkale Onsekiz Mart University Canakkale Lapseki Turkey
| | - Handan Üstükarcı
- Department of Biochemistry Faculty of Science Ege University Bornova‐Izmir 35100 Turkey
| | - Serap Evran
- Department of Biochemistry Faculty of Science Ege University Bornova‐Izmir 35100 Turkey
| | - Azmi Telefoncu
- Department of Biochemistry Faculty of Science Ege University Bornova‐Izmir 35100 Turkey
- Bio‐sensing and Bioinformatics Nanotechnologies R & D Trade & Ind. Ltd Co TECHNOPARK EGE, Ege University 35100 Izmir Turkey
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17
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Bae JE, Kim IJ, Nam KH. Spectroscopic Analysis of the Cu2+-Induced Fluorescence Quenching of Fluorescent Proteins AmCyan and mOrange2. Mol Biotechnol 2018; 60:485-491. [DOI: 10.1007/s12033-018-0088-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Wechakorn K, Prabpai S, Suksen K, Kanjanasirirat P, Pewkliang Y, Borwornpinyo S, Kongsaeree P. A rhodamine-triazole fluorescent chemodosimeter for Cu2+
detection and its application in bioimaging. LUMINESCENCE 2017; 33:64-70. [DOI: 10.1002/bio.3373] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/28/2017] [Accepted: 05/31/2017] [Indexed: 01/13/2023]
Affiliation(s)
- Kanokorn Wechakorn
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science; Mahidol University; Bangkok Thailand
- Center for Excellence in Protein and Enzyme Technology, Faculty of Science; Mahidol University; Bangkok Thailand
| | - Samran Prabpai
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science; Mahidol University; Bangkok Thailand
- Center for Excellence in Protein and Enzyme Technology, Faculty of Science; Mahidol University; Bangkok Thailand
| | - Kanoknetr Suksen
- Department of Physiology, Faculty of Science; Mahidol University; Bangkok Thailand
| | | | - Yongyut Pewkliang
- Excellent Center for Drug Discovery, Faculty of Science; Mahidol University; Bangkok Thailand
| | - Suparerk Borwornpinyo
- Excellent Center for Drug Discovery, Faculty of Science; Mahidol University; Bangkok Thailand
- Department of Biotechnology, Faculty of Science; Mahidol University; Bangkok Thailand
| | - Palangpon Kongsaeree
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science; Mahidol University; Bangkok Thailand
- Center for Excellence in Protein and Enzyme Technology, Faculty of Science; Mahidol University; Bangkok Thailand
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19
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Kim IJ, Kim S, Park J, Eom I, Kim S, Kim JH, Ha SC, Kim YG, Hwang KY, Nam KH. Crystal structures of Dronpa complexed with quenchable metal ions provide insight into metal biosensor development. FEBS Lett 2016; 590:2982-90. [DOI: 10.1002/1873-3468.12316] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/27/2016] [Accepted: 07/11/2016] [Indexed: 11/12/2022]
Affiliation(s)
- In Jung Kim
- Division of Biotechnology; College of Life Sciences & Biotechnology; Korea University; Seoul Korea
| | - Sangsoo Kim
- Pohang Accelerator Laboratory; Pohang University of Science and Technology; Korea
| | - Jeahyun Park
- Pohang Accelerator Laboratory; Pohang University of Science and Technology; Korea
| | - Intae Eom
- Pohang Accelerator Laboratory; Pohang University of Science and Technology; Korea
| | - Sunam Kim
- Pohang Accelerator Laboratory; Pohang University of Science and Technology; Korea
| | - Jin-Hong Kim
- Pohang Accelerator Laboratory; Pohang University of Science and Technology; Korea
| | - Sung Chul Ha
- Pohang Accelerator Laboratory; Pohang University of Science and Technology; Korea
| | - Yeon Gil Kim
- Pohang Accelerator Laboratory; Pohang University of Science and Technology; Korea
| | - Kwang Yeon Hwang
- Division of Biotechnology; College of Life Sciences & Biotechnology; Korea University; Seoul Korea
| | - Ki Hyun Nam
- Pohang Accelerator Laboratory; Pohang University of Science and Technology; Korea
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20
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Fluorescence of a Histidine-Modified Enhanced Green Fluorescent Protein (EGFP) Effectively Quenched by Copper(II) Ions. Part II. Molecular Determinants. J Fluoresc 2015; 25:871-83. [DOI: 10.1007/s10895-015-1567-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 04/10/2015] [Indexed: 12/15/2022]
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21
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Lei C, Wang Z, Nie Z, Deng H, Hu H, Huang Y, Yao S. Resurfaced fluorescent protein as a sensing platform for label-free detection of copper(II) ion and acetylcholinesterase activity. Anal Chem 2015; 87:1974-80. [PMID: 25560517 DOI: 10.1021/ac504390e] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Protein engineering by resurfacing is an efficient approach to provide new molecular toolkits for biotechnology and bioanalytical chemistry. H39GFP is a new variant of green fluorescent protein (GFP) containing 39 histidine residues in the primary sequence that was developed by protein resurfacing. Herein, taking H39GFP as the signal reporter, a label-free fluorometric sensor for Cu(2+) sensing was developed based on the unique multivalent metal ion-binding property of H39GFP and fluorescence quenching effect of Cu(2+) by electron transfer. The high affinity of H39GFP with Cu(2+) (Kd, 16.2 nM) leads to rapid detection of Cu(2+) in 5 min with a low detection limit (50 nM). Using acetylthiocholine (ATCh) as the substrate, this H39GFP/Cu(2+) complex-based sensor was further applied for the turn-on fluorescence detection of acetylcholinesterase (AChE) activity. The assay was based on the reaction between Cu(2+) and thiocholine, the hydrolysis product of ATCh by AChE. The proposed sensor is highly sensitive (limit of detection (LOD) = 0.015 mU mL(-1)) and is feasible for screening inhibitors of AChE. Furthermore, the practicability of this method was demonstrated by the detection of pesticide residue (carbaryl) in real food samples. Hence, the successful applications of H39GFP in the detection of metal ion and enzyme activity present the prospect of resurfaced proteins as versatile biosensing platforms.
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Affiliation(s)
- Chunyang Lei
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, P. R. China
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22
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Nantasenamat C, Simeon S, Owasirikul W, Songtawee N, Lapins M, Prachayasittikul V, Wikberg JES. Illuminating the origins of spectral properties of green fluorescent proteins via proteochemometric and molecular modeling. J Comput Chem 2014; 35:1951-66. [DOI: 10.1002/jcc.23708] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 04/28/2014] [Accepted: 07/28/2014] [Indexed: 01/06/2023]
Affiliation(s)
- Chanin Nantasenamat
- Center of Data Mining and Biomedical Informatics; Faculty of Medical Technology, Mahidol University; Bangkok 10700 Thailand
- Department of Clinical Microbiology and Applied Technology; Faculty of Medical Technology, Mahidol University; Bangkok 10700 Thailand
| | - Saw Simeon
- Center of Data Mining and Biomedical Informatics; Faculty of Medical Technology, Mahidol University; Bangkok 10700 Thailand
| | - Wiwat Owasirikul
- Center of Data Mining and Biomedical Informatics; Faculty of Medical Technology, Mahidol University; Bangkok 10700 Thailand
- Department of Radiological Technology; Faculty of Medical Technology, Mahidol University; Bangkok 10700 Thailand
| | - Napat Songtawee
- Center of Data Mining and Biomedical Informatics; Faculty of Medical Technology, Mahidol University; Bangkok 10700 Thailand
| | - Maris Lapins
- Department of Pharmaceutical Biosciences; Uppsala University; Uppsala Sweden
| | - Virapong Prachayasittikul
- Department of Clinical Microbiology and Applied Technology; Faculty of Medical Technology, Mahidol University; Bangkok 10700 Thailand
| | - Jarl E. S. Wikberg
- Department of Pharmaceutical Biosciences; Uppsala University; Uppsala Sweden
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23
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Yu X, Strub MP, Barnard TJ, Noinaj N, Piszczek G, Buchanan SK, Taraska JW. An engineered palette of metal ion quenchable fluorescent proteins. PLoS One 2014; 9:e95808. [PMID: 24752441 PMCID: PMC3994163 DOI: 10.1371/journal.pone.0095808] [Citation(s) in RCA: 15] [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: 02/03/2014] [Accepted: 03/31/2014] [Indexed: 12/17/2022] Open
Abstract
Many fluorescent proteins have been created to act as genetically encoded biosensors. With these sensors, changes in fluorescence report on chemical states in living cells. Transition metal ions such as copper, nickel, and zinc are crucial in many physiological and pathophysiological pathways. Here, we engineered a spectral series of optimized transition metal ion-binding fluorescent proteins that respond to metals with large changes in fluorescence intensity. These proteins can act as metal biosensors or imaging probes whose fluorescence can be tuned by metals. Each protein is uniquely modulated by four different metals (Cu2+, Ni2+, Co2+, and Zn2+). Crystallography revealed the geometry and location of metal binding to the engineered sites. When attached to the extracellular terminal of a membrane protein VAMP2, dimeric pairs of the sensors could be used in cells as ratiometric probes for transition metal ions. Thus, these engineered fluorescent proteins act as sensitive transition metal ion-responsive genetically encoded probes that span the visible spectrum.
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Affiliation(s)
- Xiaozhen Yu
- Laboratory of Molecular Biophysics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Marie-Paule Strub
- Laboratory of Molecular Biophysics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Travis J. Barnard
- Laboratory of Molecular Biology, National Institute Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nicholas Noinaj
- Laboratory of Molecular Biology, National Institute Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Grzegorz Piszczek
- Laboratory of Biochemistry, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Susan K. Buchanan
- Laboratory of Molecular Biology, National Institute Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Justin W. Taraska
- Laboratory of Molecular Biophysics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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24
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Masullo T, Puccio R, Di Pierro M, Tagliavia M, Censi P, Vetri V, Militello V, Cuttitta A, Colombo P. Development of a Biosensor for Copper Detection in Aqueous Solutions Using an Anemonia sulcata Recombinant GFP. Appl Biochem Biotechnol 2013; 172:2175-87. [DOI: 10.1007/s12010-013-0669-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 12/01/2013] [Indexed: 10/25/2022]
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25
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Bazin D, Chevalier S, Saadaoui H, Santarelli X, Larpent C, Feracci H, Faure C. Electrodeposition of polymer nanodots with controlled density and their reversible functionalization by polyhistidine-tag proteins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:13968-13975. [PMID: 22937837 DOI: 10.1021/la301063s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present a simple and rapid procedure for producing polymer-coated substrates that can be easily functionalized by ion-chelating proteins. The procedure consists of depositing 18 nm metal-chelating cyclam-modified polymer nanoparticles (cyclam-nps) onto a conductive substrate (an Indium Tin Oxide (ITO) electrode) from an aqueous dispersion of Cu(2+)-loaded cyclam-nps while being subjected to a direct current (DC) field. The density of deposited nps as measured by AFM is shown to be in direct correlation to the concentration of nps in the dispersion with deposition of the particles taking less than 5 s. Because of the functionalization of the nps with cyclam groups, they can be used as anchoring sites for 6-Histidine (6-His) tagged proteins through complexation with divalent metal ions. In this work 6-His Green Fluorescent Protein (6-His GFP) is used as a model protein. The characterization by fluorescence microscopy clearly shows that the protein affinity was ion dependent and that the 6-His GFP density can be controlled by np density, which is itself easily tunable. AFM observations confirmed the immobilization of 6-His GFP onto cyclam-nps and its subsequent removal by treatment with ethylenediaminetetraacetic acid (EDTA).
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Affiliation(s)
- Damien Bazin
- Centre de Recherche Paul Pascal-Université de Bordeaux 1, Pessac, France
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26
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Determination of copper(II) ion concentration by lifetime measurements of green fluorescent protein. J Fluoresc 2011; 21:2143-53. [PMID: 21773693 DOI: 10.1007/s10895-011-0916-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 07/04/2011] [Indexed: 10/18/2022]
Abstract
The understanding of cellular processes and functions and the elucidation of their physiological mechanisms is an important aim in the life sciences. One important aspect is the uptake and the release of essential substances as well as their interactions with the cellular environment. As green fluorescent protein (GFP) can be genetically encoded in cells it can be used as an internal sensor giving a deeper insight into biochemical pathways. Here we report that the presence of copper(II) ions leads to a decrease of the fluorescence lifetime (τ(fl)) of GFP and provide evidence for Förster resonance energy transfer (FRET) as the responsible quenching mechanism. We identify the His(6)-tag as the responsible binding site for Cu(2+) with a dissociation constant K(d) = 9 ± 2 μM and a Förster radius R(0) = 2.1 ± 0.1 nm. The extent of the lifetime quenching depends on [Cu(2+)] which is comprehended by a mathematical titration model. We envision that Cu(2+) can be quantified noninvasively and in real-time by measuring τ(fl) of GFP.
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27
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Ayyadurai N, Saravanan Prabhu N, Deepankumar K, Lee SG, Jeong HH, Lee CS, Yun H. Development of a Selective, Sensitive, and Reversible Biosensor by the Genetic Incorporation of a Metal-Binding Site into Green Fluorescent Protein. Angew Chem Int Ed Engl 2011; 50:6534-7. [DOI: 10.1002/anie.201008289] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Revised: 04/19/2011] [Indexed: 11/06/2022]
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28
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Development of a Selective, Sensitive, and Reversible Biosensor by the Genetic Incorporation of a Metal-Binding Site into Green Fluorescent Protein. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201008289] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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