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Abstract
The genetically encoded fluorescent sensors convert chemical and physical signals into light. They are powerful tools for the visualisation of physiological processes in living cells and freely moving animals. The fluorescent protein is the reporter module of a genetically encoded biosensor. In this study, we first review the history of the fluorescent protein in full emission spectra on a structural basis. Then, we discuss the design of the genetically encoded biosensor. Finally, we briefly review several major types of genetically encoded biosensors that are currently widely used based on their design and molecular targets, which may be useful for the future design of fluorescent biosensors.
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Affiliation(s)
- Minji Wang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhong Shan Road North, Shanghai, 200062, China
| | - Yifan Da
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhong Shan Road North, Shanghai, 200062, China
| | - Yang Tian
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhong Shan Road North, Shanghai, 200062, China
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2
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Gupta D, Sharma G, Saraswat P, Ranjan R. Synthetic Biology in Plants, a Boon for Coming Decades. Mol Biotechnol 2021; 63:1138-1154. [PMID: 34420149 DOI: 10.1007/s12033-021-00386-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 08/16/2021] [Indexed: 02/01/2023]
Abstract
Recently an enormous expansion of knowledge is seen in various disciplines of science. This surge of information has given rise to concept of interdisciplinary fields, which has resulted in emergence of newer research domains, one of them is 'Synthetic Biology' (SynBio). It captures basics from core biology and integrates it with concepts from the other areas of study such as chemical, electrical, and computational sciences. The essence of synthetic biology is to rewire, re-program, and re-create natural biological pathways, which are carried through genetic circuits. A genetic circuit is a functional assembly of basic biological entities (DNA, RNA, proteins), created using typical design, built, and test cycles. These circuits allow scientists to engineer nearly all biological systems for various useful purposes. The development of sophisticated molecular tools, techniques, genomic programs, and ease of nucleic acid synthesis have further fueled several innovative application of synthetic biology in areas like molecular medicines, pharmaceuticals, biofuels, drug discovery, metabolomics, developing plant biosensors, utilization of prokaryotic systems for metabolite production, and CRISPR/Cas9 in the crop improvement. These applications have largely been dominated by utilization of prokaryotic systems. However, newer researches have indicated positive growth of SynBio for the eukaryotic systems as well. This paper explores advances of synthetic biology in the plant field by elaborating on its core components and potential applications. Here, we have given a comprehensive idea of designing, development, and utilization of synthetic biology in the improvement of the present research state of plant system.
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Affiliation(s)
- Dipinte Gupta
- Plant Biotechnology Lab, Department of Botany, Faculty of Science, Dayalbagh Educational Institute (Deemed to be University), Dayalbagh, Agra, 282005, India
| | - Gauri Sharma
- Plant Biotechnology Lab, Department of Botany, Faculty of Science, Dayalbagh Educational Institute (Deemed to be University), Dayalbagh, Agra, 282005, India
| | - Pooja Saraswat
- Plant Biotechnology Lab, Department of Botany, Faculty of Science, Dayalbagh Educational Institute (Deemed to be University), Dayalbagh, Agra, 282005, India
| | - Rajiv Ranjan
- Plant Biotechnology Lab, Department of Botany, Faculty of Science, Dayalbagh Educational Institute (Deemed to be University), Dayalbagh, Agra, 282005, India.
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3
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Agrawal N, Soleja N, Bano R, Nazir R, Siddiqi TO, Mohsin M. FRET-Based Genetically Encoded Sensor to Monitor Silver Ions. ACS OMEGA 2021; 6:14164-14173. [PMID: 34124439 PMCID: PMC8190795 DOI: 10.1021/acsomega.1c00741] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/29/2021] [Indexed: 06/12/2023]
Abstract
Silver is commonly used in wound dressing, photography, health care products, laboratories, pharmacy, biomedical devices, and several industrial purposes. Silver (Ag+) ions are more toxic pollutants widely scattered in the open environment by natural processes and dispersed in soil, air, and water bodies. Ag+ binds with metallothionein, macroglobulins, and albumins, which may lead to the alteration of various enzymatic metabolic pathways. To analyze the uptake and metabolism of silver ions in vitro as well as in cells, a range of high-affinity fluorescence-based nanosensors has been constructed using a periplasmic protein CusF, a part of the CusCFBA efflux complex, which is involved in providing resistance against copper and silver ions in Escherichia coli. This nanosensor was constructed by combining of two fluorescent proteins (donor and acceptor) at the N- and C-terminus of the silver-binding protein (CusF), respectively. SenSil (WT) with a binding constant (K d) of 5.171 μM was more efficient than its mutant variants (H36D and F71W). This nanosensor allows monitoring the level of silver ions in real time in prokaryotes and eukaryotes without any disruption of cells or tissues.
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Affiliation(s)
- Neha Agrawal
- Department
of Biosciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Neha Soleja
- Department
of Biosciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Reshma Bano
- Department
of Biosciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Rahila Nazir
- Department
of Botany, Jamia Hamdard, New Delhi 110062, India
| | | | - Mohd Mohsin
- Department
of Biosciences, Jamia Millia Islamia, New Delhi 110025, India
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4
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Naz R, Okla MK, Fatima U, Mohsin M, Soufan WH, Alaraidh IA, Abdel-Maksoud MA, Ahmad A. Designing and Development of FRET-Based Nanosensor for Real Time Analysis of N-Acetyl-5-Neuraminic Acid in Living Cells. Front Nutr 2021; 8:621273. [PMID: 34136513 PMCID: PMC8200523 DOI: 10.3389/fnut.2021.621273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 04/28/2021] [Indexed: 12/22/2022] Open
Abstract
N-acetyl-5-neuraminic acid (NeuAc) plays crucial role in improving the growth, brain development, brain health maintenance, and immunity enhancement of infants. Commercially, it is used in the production of antiviral drugs, infant milk formulas, cosmetics, dietary supplements, and pharmaceutical products. Because of the rapidly increasing demand, metabolic engineering approach has attracted increasing attention for NeuAc biosynthesis. However, knowledge of metabolite flux in biosynthetic pathways is one of the major challenges in the practice of metabolic engineering. So, an understanding of the flux of NeuAc is needed to determine its cellular level at real time. The analysis of the flux can only be performed using a tool that has the capacity to measure metabolite level in cells without affecting other metabolic processes. A Fluorescence Resonance Energy Transfer (FRET)-based genetically-encoded nanosensor has been generated in this study to monitor the level of NeuAc in prokaryotic and eukaryotic cells. Sialic acid periplasmic binding protein (SiaP) from Haemophilus influenzae was exploited as a sensory element for the generation of nanosensor. The enhanced cyan fluorescent protein (ECFP) and Venus were used as Fluroscence Resonance Energy Transfer (FRET) pair. The nanosensor, which was termed fluorescent indicator protein for sialic acid (FLIP-SA), was successfully transformed into, and expressed in Escherichia coli BL21 (DE3) cells. The expressed protein of the nanosensor was isolated and purified. The purified nanosensor protein was characterized to assess the affinity, specificity, and stability in the pH range. The developed nanosensor exhibited FRET change after addition to NeuAc. The developed nanosensor was highly specific, exhibited pH stability, and detected NeuAc levels in the nanomolar to milimolar range. FLIP-SA was successfully introduced in bacterial and yeast cells and reported the real-time intracellular levels of NeuAc non-invasively. The FLIP-SA is an excellent tool for the metabolic flux analysis of the NeuAc biosynthetic pathway and, thus, may help unravel the regulatory mechanism of the metabolic pathway of NeuAc. Furthermore, FLIP-SA can be used for the high-throughput screening of E. coli mutant libraries for varied NeuAc production levels.
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Affiliation(s)
- Ruphi Naz
- Department of Botany, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, India
| | - Mohammad K Okla
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Urooj Fatima
- Department of Botany, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, India
| | - Mohd Mohsin
- Department of Biosciences, Jamia Millia Islamia, New Delhi, India
| | - Walid H Soufan
- Department of Plant Production, Faculty of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Ibrahim A Alaraidh
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | | | - Altaf Ahmad
- Department of Botany, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, India
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5
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Zemerov SD, Roose BW, Farenhem KL, Zhao Z, Stringer MA, Goldman AR, Speicher DW, Dmochowski IJ. 129Xe NMR-Protein Sensor Reveals Cellular Ribose Concentration. Anal Chem 2020; 92:12817-12824. [PMID: 32897053 PMCID: PMC7649717 DOI: 10.1021/acs.analchem.0c00967] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Dysregulation of cellular ribose uptake can be indicative of metabolic abnormalities or tumorigenesis. However, analytical methods are currently limited for quantifying ribose concentration in complex biological samples. Here, we utilize the highly specific recognition of ribose by ribose-binding protein (RBP) to develop a single-protein ribose sensor detectable via a sensitive NMR technique known as hyperpolarized 129Xe chemical exchange saturation transfer (hyper-CEST). We demonstrate that RBP, with a tunable ribose-binding site and further engineered to bind xenon, enables the quantitation of ribose over a wide concentration range (nM to mM). Ribose binding induces the RBP "closed" conformation, which slows Xe exchange to a rate detectable by hyper-CEST. Such detection is remarkably specific for ribose, with the minimal background signal from endogenous sugars of similar size and structure, for example, glucose or ribose-6-phosphate. Ribose concentration was measured for mammalian cell lysate and serum, which led to estimates of low-mM ribose in a HeLa cell line. This highlights the potential for using genetically encoded periplasmic binding proteins such as RBP to measure metabolites in different biological fluids, tissues, and physiologic states.
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Affiliation(s)
- Serge D. Zemerov
- Department of Chemistry, University of Pennsylvania,
Philadelphia, PA 19104, USA
| | - Benjamin W. Roose
- Department of Chemistry, University of Pennsylvania,
Philadelphia, PA 19104, USA
| | - Kelsey L. Farenhem
- Department of Chemistry, University of Pennsylvania,
Philadelphia, PA 19104, USA
| | - Zhuangyu Zhao
- Department of Chemistry, University of Pennsylvania,
Philadelphia, PA 19104, USA
| | - Madison A. Stringer
- Department of Chemistry, University of Pennsylvania,
Philadelphia, PA 19104, USA
| | - Aaron R. Goldman
- Proteomics and Metabolomics Facility, The Wistar Institute,
Philadelphia, PA 19104, USA
| | - David W. Speicher
- Proteomics and Metabolomics Facility, The Wistar Institute,
Philadelphia, PA 19104, USA
- Molecular and Cellular Oncogenesis Program, The Wistar
Institute, Philadelphia, PA 19104, USA
| | - Ivan J. Dmochowski
- Department of Chemistry, University of Pennsylvania,
Philadelphia, PA 19104, USA
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6
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Funck D, Baumgarten L, Stift M, von Wirén N, Schönemann L. Differential Contribution of P5CS Isoforms to Stress Tolerance in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2020; 11:565134. [PMID: 33101333 PMCID: PMC7545825 DOI: 10.3389/fpls.2020.565134] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/09/2020] [Indexed: 05/24/2023]
Abstract
Proline accumulation is a widespread response of plants to salt stress as well as drought and cold stress. In most plant species, two isoforms of pyrroline-5-carboxylate synthetase (P5CS) catalyze the first step in proline biosynthesis from glutamate. In Arabidopsis, these isoforms differ in their spatial and temporal expression patterns, suggesting sub-functionalization. P5CS1 has been identified as the major contributor to stress-induced proline accumulation, whereas P5CS2 has been considered important for embryo development and growth. In contrast to previous results, our analysis of P5CS1- and P5CS2-GFP fusion proteins indicates that both enzymes were exclusively localized in the cytosol. The comparison of the susceptibility of p5cs1 and p5cs2 mutants to infection with Pseudomonas syringae and salt stress provided novel information on the contribution of the two P5CS isoforms to proline accumulation and stress tolerance. In agreement with previous studies, salt-stressed p5cs1 mutants accumulated very little proline, indicating that P5CS1 contributed more to stress-induced proline accumulation, whereas its impact on stress tolerance was rather weak. Germination and establishment of p5cs2 mutants were impaired under ambient conditions, further supporting that P5CS2 is most important for growth and development, whereas its contribution to stress-induced proline accumulation was smaller than that of P5CS1. In contrast to p5cs1 mutants or wildtype plants, p5cs2 mutants were only weakly affected by sudden exposure to a high NaCl concentration. These findings show that proline content, which was intermediate in leaves of p5cs2 mutants, was not directly correlated with stress tolerance in our experiments. In rosettes of NaCl-exposed p5cs2 mutants, nearly no accumulation of Na+ was observed, and the plants showed neither chlorosis nor reduction of photosynthesis. Based on these data, we suggest a function of P5CS2 or P5CS2-mediated proline synthesis in regulating Na+ accumulation in leaves and thereby salt stress tolerance.
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Affiliation(s)
- Dietmar Funck
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Lukas Baumgarten
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Marc Stift
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Nicolaus von Wirén
- Molecular Plant Nutrition, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Luise Schönemann
- Department of Biology, University of Konstanz, Konstanz, Germany
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Dalangin R, Kim A, Campbell RE. The Role of Amino Acids in Neurotransmission and Fluorescent Tools for Their Detection. Int J Mol Sci 2020; 21:E6197. [PMID: 32867295 PMCID: PMC7503967 DOI: 10.3390/ijms21176197] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/17/2020] [Accepted: 08/24/2020] [Indexed: 12/20/2022] Open
Abstract
Neurotransmission between neurons, which can occur over the span of a few milliseconds, relies on the controlled release of small molecule neurotransmitters, many of which are amino acids. Fluorescence imaging provides the necessary speed to follow these events and has emerged as a powerful technique for investigating neurotransmission. In this review, we highlight some of the roles of the 20 canonical amino acids, GABA and β-alanine in neurotransmission. We also discuss available fluorescence-based probes for amino acids that have been shown to be compatible for live cell imaging, namely those based on synthetic dyes, nanostructures (quantum dots and nanotubes), and genetically encoded components. We aim to provide tool developers with information that may guide future engineering efforts and tool users with information regarding existing indicators to facilitate studies of amino acid dynamics.
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Affiliation(s)
- Rochelin Dalangin
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (R.D.); (A.K.)
| | - Anna Kim
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (R.D.); (A.K.)
| | - Robert E. Campbell
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (R.D.); (A.K.)
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo City, Tokyo 113-0033, Japan
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8
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Real-time monitoring of glutathione in living cells using genetically encoded FRET-based ratiometric nanosensor. Sci Rep 2020; 10:992. [PMID: 31969596 PMCID: PMC6976633 DOI: 10.1038/s41598-020-57654-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 01/02/2020] [Indexed: 01/11/2023] Open
Abstract
Reduced glutathione (GSH) level inside the cell is a critical determinant for cell viability. The level of GSH varies across the cells, tissues and environmental conditions. However, our current understanding of physiological and pathological GSH changes at high spatial and temporal resolution is limited due to non-availability of practicable GSH-detection methods. In order to measure GSH at real-time, a ratiometric genetically encoded nanosensor was developed using fluorescent proteins and fluorescence resonance energy transfer (FRET) approach. The construction of the sensor involved the introduction of GSH binding protein (YliB) as a sensory domain between cyan fluorescent protein (CFP; FRET donor) and yellow fluorescent protein (YFP; FRET acceptor). The developed sensor, named as FLIP-G (Fluorescence Indicator Protein for Glutathione) was able to measure the GSH level under in vitro and in vivo conditions. When the purified FLIP-G was titrated with different concentrations of GSH, the FRET ratio increased with increase in GSH-concentration. The sensor was found to be specific for GSH and also stable to changes in pH. Moreover, in live bacterial cells, the constructed sensor enabled the real-time quantification of cytosolic GSH that is controlled by the oxidative stress level. When expressed in yeast cells, FRET ratio increased with the external supply of GSH to living cells. Therefore, as a valuable tool, the developed FLIP-G can monitor GSH level in living cells and also help in gaining new insights into GSH metabolism.
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9
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Soleja N, Manzoor O, Khan P, Mohsin M. Engineering genetically encoded FRET-based nanosensors for real time display of arsenic (As 3+) dynamics in living cells. Sci Rep 2019; 9:11240. [PMID: 31375744 PMCID: PMC6677752 DOI: 10.1038/s41598-019-47682-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 07/12/2019] [Indexed: 02/07/2023] Open
Abstract
Arsenic poisoning has been a major concern that causes severe toxicological damages. Therefore, intricate and inclusive understanding of arsenic flux rates is required to ascertain the cellular concentration and establish the carcinogenetic mechanism of this toxicant at real time. The lack of sufficiently sensitive sensing systems has hampered research in this area. In this study, we constructed a fluorescent resonance energy transfer (FRET)-based nanosensor, named SenALiB (Sensor for Arsenic Linked Blackfoot disease) which contains a metalloregulatory arsenic-binding protein (ArsR) as the As3+ sensing element inserted between the FRET pair enhanced cyan fluorescent protein (ECFP) and Venus. SenALiB takes advantage of the ratiometic FRET readout which measures arsenic with high specificity and selectivity. SenALiB offers rapid detection response, is stable to pH changes and provides highly accurate, real-time optical readout in cell-based assays. SenALiB-676n with a binding constant (Kd) of 0.676 × 10−6 M is the most efficient affinity mutant and can be a versatile tool for dynamic measurement of arsenic concentration in both prokaryotes and eukaryotes in vivo in a non-invasive manner.
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Affiliation(s)
- Neha Soleja
- Department of Biosciences, Jamia Millia Islamia, New Delhi, 110025, India
| | - Ovais Manzoor
- Department of Biosciences, Jamia Millia Islamia, New Delhi, 110025, India
| | - Parvez Khan
- Centre for Interdisciplinary Research in Basic Science, Jamia Millia Islamia, New Delhi, 110025, India
| | - Mohd Mohsin
- Department of Biosciences, Jamia Millia Islamia, New Delhi, 110025, India.
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10
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Converting a Periplasmic Binding Protein into a Synthetic Biosensing Switch through Domain Insertion. BIOMED RESEARCH INTERNATIONAL 2019; 2019:4798793. [PMID: 30719443 PMCID: PMC6335823 DOI: 10.1155/2019/4798793] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 12/17/2018] [Indexed: 12/22/2022]
Abstract
All biosensing platforms rest on two pillars: specific biochemical recognition of a particular analyte and transduction of that recognition into a readily detectable signal. Most existing biosensing technologies utilize proteins that passively bind to their analytes and therefore require wasteful washing steps, specialized reagents, and expensive instruments for detection. To overcome these limitations, protein engineering strategies have been applied to develop new classes of protein-based sensor/actuators, known as protein switches, responding to small molecules. Protein switches change their active state (output) in response to a binding event or physical signal (input) and therefore show a tremendous potential to work as a biosensor. Synthetic protein switches can be created by the fusion between two genes, one coding for a sensor protein (input domain) and the other coding for an actuator protein (output domain) by domain insertion. The binding of a signal molecule to the engineered protein will switch the protein function from an “off” to an “on” state (or vice versa) as desired. The molecular switch could, for example, sense the presence of a metabolite, pollutant, or a biomarker and trigger a cellular response. The potential sensing and response capabilities are enormous; however, the recognition repertoire of natural switches is limited. Thereby, bioengineers have been struggling to expand the toolkit of molecular switches recognition repertoire utilizing periplasmic binding proteins (PBPs) as protein-sensing components. PBPs are a superfamily of bacterial proteins that provide interesting features to engineer biosensors, for instance, immense ligand-binding diversity and high affinity, and undergo large conformational changes in response to ligand binding. The development of these protein switches has yielded insights into the design of protein-based biosensors, particularly in the area of allosteric domain fusions. Here, recent protein engineering approaches for expanding the versatility of protein switches are reviewed, with an emphasis on studies that used PBPs to generate novel switches through protein domain insertion.
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11
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Greenwald EC, Mehta S, Zhang J. Genetically Encoded Fluorescent Biosensors Illuminate the Spatiotemporal Regulation of Signaling Networks. Chem Rev 2018; 118:11707-11794. [PMID: 30550275 PMCID: PMC7462118 DOI: 10.1021/acs.chemrev.8b00333] [Citation(s) in RCA: 316] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cellular signaling networks are the foundation which determines the fate and function of cells as they respond to various cues and stimuli. The discovery of fluorescent proteins over 25 years ago enabled the development of a diverse array of genetically encodable fluorescent biosensors that are capable of measuring the spatiotemporal dynamics of signal transduction pathways in live cells. In an effort to encapsulate the breadth over which fluorescent biosensors have expanded, we endeavored to assemble a comprehensive list of published engineered biosensors, and we discuss many of the molecular designs utilized in their development. Then, we review how the high temporal and spatial resolution afforded by fluorescent biosensors has aided our understanding of the spatiotemporal regulation of signaling networks at the cellular and subcellular level. Finally, we highlight some emerging areas of research in both biosensor design and applications that are on the forefront of biosensor development.
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Affiliation(s)
- Eric C Greenwald
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Sohum Mehta
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Jin Zhang
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
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12
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Shinoda H, Shannon M, Nagai T. Fluorescent Proteins for Investigating Biological Events in Acidic Environments. Int J Mol Sci 2018; 19:E1548. [PMID: 29789517 PMCID: PMC6032295 DOI: 10.3390/ijms19061548] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/18/2018] [Accepted: 05/19/2018] [Indexed: 12/11/2022] Open
Abstract
The interior lumen of acidic organelles (e.g., endosomes, secretory granules, lysosomes and plant vacuoles) is an important platform for modification, transport and degradation of biomolecules as well as signal transduction, which remains challenging to investigate using conventional fluorescent proteins (FPs). Due to the highly acidic luminal environment (pH ~ 4.5⁻6.0), most FPs and related sensors are apt to lose their fluorescence. To address the need to image in acidic environments, several research groups have developed acid-tolerant FPs in a wide color range. Furthermore, the engineering of pH insensitive sensors, and their concomitant use with pH sensitive sensors for the purpose of pH-calibration has enabled characterization of the role of luminal ions. In this short review, we summarize the recent development of acid-tolerant FPs and related functional sensors and discuss the future prospects for this field.
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Affiliation(s)
- Hajime Shinoda
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan.
| | - Michael Shannon
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan.
| | - Takeharu Nagai
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan.
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan.
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13
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Grossmann G, Krebs M, Maizel A, Stahl Y, Vermeer JEM, Ott T. Green light for quantitative live-cell imaging in plants. J Cell Sci 2018; 131:jcs.209270. [PMID: 29361538 DOI: 10.1242/jcs.209270] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Plants exhibit an intriguing morphological and physiological plasticity that enables them to thrive in a wide range of environments. To understand the cell biological basis of this unparalleled competence, a number of methodologies have been adapted or developed over the last decades that allow minimal or non-invasive live-cell imaging in the context of tissues. Combined with the ease to generate transgenic reporter lines in specific genetic backgrounds or accessions, we are witnessing a blooming in plant cell biology. However, the imaging of plant cells entails a number of specific challenges, such as high levels of autofluorescence, light scattering that is caused by cell walls and their sensitivity to environmental conditions. Quantitative live-cell imaging in plants therefore requires adapting or developing imaging techniques, as well as mounting and incubation systems, such as micro-fluidics. Here, we discuss some of these obstacles, and review a number of selected state-of-the-art techniques, such as two-photon imaging, light sheet microscopy and variable angle epifluorescence microscopy that allow high performance and minimal invasive live-cell imaging in plants.
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Affiliation(s)
- Guido Grossmann
- Centre for Organismal Studies (COS), Heidelberg University, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.,Excellence Cluster CellNetworks, Heidelberg University, 69120 Heidelberg, Germany
| | - Melanie Krebs
- Centre for Organismal Studies (COS), Heidelberg University, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Alexis Maizel
- Centre for Organismal Studies (COS), Heidelberg University, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Yvonne Stahl
- Institute for Developmental Genetics, Heinrich-Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Joop E M Vermeer
- Laboratory for Cell Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Thomas Ott
- Faculty of Biology, Cell Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany
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14
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Avilés-Moreno JR, Berden G, Oomens J, Martínez-Haya B. Guanidinium/ammonium competition and proton transfer in the interaction of the amino acid arginine with the tetracarboxylic 18-crown-6 ionophore. Phys Chem Chem Phys 2018; 20:4067-4073. [DOI: 10.1039/c7cp07975c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The binding of arginine by the 18-crown-6 tetracarboxylic ionophore relies on extensive host–guest redistribution of electronic charge and proton transfer.
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Affiliation(s)
- Juan Ramón Avilés-Moreno
- Department of Physical
- Chemical and Natural Systems
- Universidad Pablo de Olavide
- E-41013 Seville
- Spain
| | - Giel Berden
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- Toernooiveld 7c
- The Netherlands
| | - Jos Oomens
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- Toernooiveld 7c
- The Netherlands
| | - Bruno Martínez-Haya
- Department of Physical
- Chemical and Natural Systems
- Universidad Pablo de Olavide
- E-41013 Seville
- Spain
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15
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Okumoto S, Versaw W. Genetically encoded sensors for monitoring the transport and concentration of nitrogen-containing and phosphorus-containing molecules in plants. CURRENT OPINION IN PLANT BIOLOGY 2017; 39:129-135. [PMID: 28750256 DOI: 10.1016/j.pbi.2017.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/06/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023]
Abstract
Nitrogen and phosphorus are macronutrients indispensable for plant growth. The acquisition and reallocation of both elements require a multitude of dedicated transporters that specifically recognize inorganic and organic forms of nitrogen and phosphorous. Although many transporters have been discovered through elegant screening processes and sequence homology, many remain uncharacterized for their functions in planta. Genetically encoded sensors for nitrogen and phosphorous molecules offer a unique opportunity for studying transport mechanisms that were previously inaccessible. In the past few years, sensors for some of the key nitrogen molecules became available, and many improvements have been made for existing sensors for phosphorus molecules. Methodologies for detailed in vivo analysis also improved. We summarize the recent improvements in genetically encoded sensors for nitrogen and phosphorus molecules, and the discoveries made by using such sensors.
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Affiliation(s)
- Sakiko Okumoto
- Department of Soil and Crop Sciences, Texas A&M University, HEEP Center, College Station, TX 77843 USA.
| | - Wayne Versaw
- Department of Biology, Texas A&M University, Biological Sciences Building East, College Station, TX 77843 USA
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16
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Pelosse M, Cottet-Rousselle C, Grichine A, Berger I, Schlattner U. Genetically Encoded Fluorescent Biosensors to Explore AMPK Signaling and Energy Metabolism. ACTA ACUST UNITED AC 2017; 107:491-523. [PMID: 27812993 DOI: 10.1007/978-3-319-43589-3_20] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Maintenance of energy homeostasis is a basic requirement for cell survival. Different mechanisms have evolved to cope with spatial and temporal mismatch between energy-providing and -consuming processes. Among these, signaling by AMP-activated protein kinase (AMPK) is one of the key players, regulated by and itself regulating cellular adenylate levels. Further understanding its complex cellular function requires deeper insight into its activation patterns in space and time at a single cell level. This may become possible with an increasing number of genetically encoded fluorescent biosensors, mostly based on fluorescence resonance energy transfer, which have been engineered to monitor metabolic parameters and kinase activities. Here, we review basic principles of biosensor design and function and the advantages and limitations of their use and provide an overview on existing FRET biosensors to monitor AMPK activation, ATP concentration, and ATP/ADP ratios, together with other key metabolites and parameters of energy metabolism.
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Affiliation(s)
- Martin Pelosse
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy), University Grenoble Alpes, Grenoble, France.,Inserm, U1055 and U1209, Grenoble, France
| | - Cécile Cottet-Rousselle
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy), University Grenoble Alpes, Grenoble, France.,Inserm, U1055 and U1209, Grenoble, France
| | - Alexei Grichine
- Inserm, U1055 and U1209, Grenoble, France.,Institute for Advanced Biosciences, University Grenoble Alpes, Grenoble, France
| | | | - Uwe Schlattner
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy), University Grenoble Alpes, Grenoble, France. .,Inserm, U1055 and U1209, Grenoble, France.
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17
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18
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Genetic biosensors for small-molecule products: Design and applications in high-throughput screening. Front Chem Sci Eng 2017. [DOI: 10.1007/s11705-017-1629-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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19
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Mitchell JA, Whitfield JH, Zhang WH, Henneberger C, Janovjak H, O’Mara ML, Jackson CJ. Rangefinder: A Semisynthetic FRET Sensor Design Algorithm. ACS Sens 2016. [DOI: 10.1021/acssensors.6b00576] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joshua A. Mitchell
- Research
School of Chemistry, Australian National University, Canberra, 2601, Australia
| | - Jason H. Whitfield
- Research
School of Chemistry, Australian National University, Canberra, 2601, Australia
| | - William H. Zhang
- Research
School of Chemistry, Australian National University, Canberra, 2601, Australia
| | - Christian Henneberger
- Institute
of Neurology, University College London, London, WC1E 6BT, United Kingdom
- German Center for Neurodegenerative Diseases (DZNE), 53175 Bonn, Germany
- Institute
of Cellular Neurosciences, University of Bonn, 53113 Bonn, Germany
| | - Harald Janovjak
- Institute of Science and Technology, 3400 Klosterneuburg, Austria
| | - Megan L. O’Mara
- Research
School of Chemistry, Australian National University, Canberra, 2601, Australia
| | - Colin J. Jackson
- Research
School of Chemistry, Australian National University, Canberra, 2601, Australia
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20
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Ameen S, Ahmad M, Mohsin M, Qureshi MI, Ibrahim MM, Abdin MZ, Ahmad A. Designing, construction and characterization of genetically encoded FRET-based nanosensor for real time monitoring of lysine flux in living cells. J Nanobiotechnology 2016; 14:49. [PMID: 27334743 PMCID: PMC4917951 DOI: 10.1186/s12951-016-0204-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 06/09/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Engineering microorganisms in order to improve the metabolite flux needs a detailed knowledge of the concentrations and flux rates of metabolites and metabolic intermediates in vivo. Fluorescence resonance energy transfer (FRET) based genetically encoded nanosensors represent a promising tool for measuring the metabolite levels and corresponding rate changes in live cells. Here, we report the development of a series of FRET based genetically encoded nanosensor for real time measurement of lysine at cellular level, as the improvement of microbial strains for the production of L-lysine is of major interest in industrial biotechnology. RESULTS The lysine binding periplasmic protein (LAO) from Salmonella enterica serovar typhimurium LT2 strain was used as the reporter element for the sensor. The LAO was sandwiched between GFP variants i.e. cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP). Affinity, pH stability, specificity and metal ions effects was scrutinized for the in vitro characterization of this nanosensor, named as FLIPK. The FLIPK is specific to lysine and found to be stable with the pH within the physiological range. The calculated affinity (K d ) of FLIPK was 97 µM. For physiological applications, mutants with different binding affinities were also generated and investigated in vitro. The developed nanosensor efficiently monitored the intracellular level of lysine in bacterial as well as yeast cell. CONCLUSION The developed novel lysine fluorescence resonance energy transfer sensors can be used for in vivo monitoring of lysine levels in prokaryotes as well as eukaryotes. The potential of these sensors is that they can be used as reporter tools in the development of metabolically engineered microbial strains or for real-time monitoring of intracellular lysine during fermentation.
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Affiliation(s)
- Seema Ameen
- Department of Botany, Faculty of Science, Hamdard University, New Delhi, India
| | - Mohammad Ahmad
- Department of Botany, Faculty of Science, Hamdard University, New Delhi, India
| | - Mohd Mohsin
- Department of Biosciences, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi, India
| | - M Irfan Qureshi
- Department of Biotechnology, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi, India
| | - Mohamed M Ibrahim
- Department of Botany & Microbiology, Science College, King Saud University, P.O. Box 2455, Riyadh, Saudi Arabia.,Department of Botany & Microbiology, Faculty of Science, Alexandria University, P.O. Box 21511, Alexandria, Egypt
| | - Malik Z Abdin
- Department of Biotechnology, Faculty of Science, Hamdard University, New Delhi, India
| | - Altaf Ahmad
- Department of Botany, Faculty of Science, Hamdard University, New Delhi, India. .,Department of Botany, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, India.
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21
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Ahmad M, Ameen S, Siddiqi TO, Khan P, Ahmad A. Live cell monitoring of glycine betaine by FRET-based genetically encoded nanosensor. Biosens Bioelectron 2016; 86:169-175. [PMID: 27371825 DOI: 10.1016/j.bios.2016.06.049] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/14/2016] [Accepted: 06/15/2016] [Indexed: 12/25/2022]
Abstract
Glycine betaine (GB) is one of the key compatible solutes that accumulate in the cell at exceedingly high level under the conditions of high salinity. It plays a crucial role in the maintenance of osmolarity of the cell without affecting the physiological processes. Analysis of stress-induced physiological conditions in living cells, therefore, requires real-time monitoring of cellular GB level. Glycine Betaine Optical Sensor (GBOS), a genetically-encoded FRET-based nanosensor developed in this study, allows the real-time monitoring of GB levels inside living cells. This nanosensor has been developed by sandwiching GB binding protein (ProX) between the Förster resonance energy transfer (FRET) pair, the cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP). Conformational change in ProX, which was used as sensory domain, reported the change in the level of this compatible solute in in vitro and in vivo conditions. Binding of the GB to the sensory domain fetches close to both the fluorescent moieties that result in the form of increased FRET ratio. So, any change in the concentration of GB is correlated with change in FRET ratio. This sensor also reported the GB cellular dynamics in real-time in Escherichia coli cells after the addition of its precursor, choline. The GBOS was also expressed in yeast and mammalian cells to monitor the intracellular GB. Therefore, the GBOS represents a unique FRET-based nanosensor which allows the non-invasive ratiometric analysis of the GB in living cells.
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Affiliation(s)
- Mohammad Ahmad
- Department of Botany, Faculty of Science, Jamia Hamdard, New Delhi, India
| | - Seema Ameen
- Department of Botany, Faculty of Science, Jamia Hamdard, New Delhi, India
| | - Tariq Omar Siddiqi
- Department of Botany, Faculty of Science, Jamia Hamdard, New Delhi, India
| | - Parvez Khan
- Center for Interdisciplinary Research in Basic Science, Jamia Millia Islamia, New Delhi, India
| | - Altaf Ahmad
- Department of Botany, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, India.
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22
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Real-time functional characterization of cationic amino acid transporters using a new FRET sensor. Pflugers Arch 2015; 468:563-72. [PMID: 26555760 DOI: 10.1007/s00424-015-1754-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 10/26/2015] [Accepted: 10/29/2015] [Indexed: 10/22/2022]
Abstract
L-arginine is a semi-essential amino acid that serves as precursor for the production of urea, nitric oxide (NO), polyamines, and other biologically important metabolites. Hence, a fast and reliable assessment of its intracellular concentration changes is highly desirable. Here, we report on a genetically encoded Förster resonance energy transfer (FRET)-based arginine nanosensor that employs the arginine repressor/activator ahrC gene from Bacillus subtilis. This new nanosensor was expressed in HEK293T cells, and experiments with cell lysate showed that it binds L-arginine with high specificity and with a K d of ∼177 μM. Live imaging experiments showed that the nanosensor was expressed throughout the cytoplasm and displayed a half maximal FRET increase at an extracellular L-arginine concentration of ∼22 μM. By expressing the nanosensor together with SLC7A1, SLC7A2B, or SLC7A3 cationic amino acid transporters (CAT1-3), it was shown that L-arginine was imported at a similar rate via SLC7A1 and SLC7A2B and slower via SLC7A3. In contrast, upon withdrawal of extracellular L-arginine, intracellular levels decreased as fast in SLC7A3-expressing cells compared with SLC7A1, but the efflux was slower via SLC7A2B. SLC7A4 (CAT4) could not be convincingly shown to transport L-arginine. We also demonstrated the impact of membrane potential on L-arginine transport and showed that physiological concentrations of symmetrical and asymmetrical dimethylarginine do not significantly interfere with L-arginine transport through SLC7A1. Our results demonstrate that the FRET nanosensor can be used to assess L-arginine transport through plasma membrane in real time.
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23
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Whitfield JH, Zhang WH, Herde MK, Clifton BE, Radziejewski J, Janovjak H, Henneberger C, Jackson CJ. Construction of a robust and sensitive arginine biosensor through ancestral protein reconstruction. Protein Sci 2015; 24:1412-22. [PMID: 26061224 DOI: 10.1002/pro.2721] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 06/05/2015] [Indexed: 11/09/2022]
Abstract
Biosensors for signaling molecules allow the study of physiological processes by bringing together the fields of protein engineering, fluorescence imaging, and cell biology. Construction of genetically encoded biosensors generally relies on the availability of a binding "core" that is both specific and stable, which can then be combined with fluorescent molecules to create a sensor. However, binding proteins with the desired properties are often not available in nature and substantial improvement to sensors can be required, particularly with regard to their durability. Ancestral protein reconstruction is a powerful protein-engineering tool able to generate highly stable and functional proteins. In this work, we sought to establish the utility of ancestral protein reconstruction to biosensor development, beginning with the construction of an l-arginine biosensor. l-arginine, as the immediate precursor to nitric oxide, is an important molecule in many physiological contexts including brain function. Using a combination of ancestral reconstruction and circular permutation, we constructed a Förster resonance energy transfer (FRET) biosensor for l-arginine (cpFLIPR). cpFLIPR displays high sensitivity and specificity, with a Kd of ∼14 µM and a maximal dynamic range of 35%. Importantly, cpFLIPR was highly robust, enabling accurate l-arginine measurement at physiological temperatures. We established that cpFLIPR is compatible with two-photon excitation fluorescence microscopy and report l-arginine concentrations in brain tissue.
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Affiliation(s)
- Jason H Whitfield
- Research School of Chemistry, Australian National University, Canberra, Australia
| | - William H Zhang
- Research School of Chemistry, Australian National University, Canberra, Australia
| | - Michel K Herde
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Ben E Clifton
- Research School of Chemistry, Australian National University, Canberra, Australia
| | - Johanna Radziejewski
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Harald Janovjak
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Christian Henneberger
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany.,Institute of Neurology, University College London, London, United Kingdom
| | - Colin J Jackson
- Research School of Chemistry, Australian National University, Canberra, Australia
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24
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FRET-based genetically-encoded sensors for quantitative monitoring of metabolites. Biotechnol Lett 2015; 37:1919-28. [DOI: 10.1007/s10529-015-1873-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 05/26/2015] [Indexed: 10/23/2022]
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25
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Yang H, Stierhof YD, Ludewig U. The putative Cationic Amino Acid Transporter 9 is targeted to vesicles and may be involved in plant amino acid homeostasis. FRONTIERS IN PLANT SCIENCE 2015; 6:212. [PMID: 25883600 PMCID: PMC4381505 DOI: 10.3389/fpls.2015.00212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/16/2015] [Indexed: 05/29/2023]
Abstract
Amino acids are major primary metabolites. Their uptake, translocation, compartmentation, and re-mobilization require a diverse set of cellular transporters. Here, the broadly expressed gene product of CATIONIC AMINO ACID TRANSPORTER 9 (CAT9) was identified as mainly localized to vesicular membranes that are involved in vacuolar trafficking, including those of the trans-Golgi network. In order to probe whether and how these compartments are involved in amino acid homeostasis, a loss-of-function cat9-1 mutant and ectopic over-expressor plants were isolated. Under restricted nitrogen supply in soil, cat9-1 showed a chlorotic phenotype, which was reversed in the over-expressors. The total soluble amino acid pools were affected in the mutants, but this was only significant under poor nitrogen supply. Upon nitrogen starvation, the soluble amino acid leaf pools were lower in the over-expressor, compared with cat9-1. Over-expression generally affected total soluble amino acid concentrations, slightly delayed development, and finally improved the survival upon severe nitrogen starvation. The results potentially identify a novel function of vesicular amino acid transport mediated by CAT9 in the cellular nitrogen-dependent amino acid homeostasis.
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Affiliation(s)
- Huaiyu Yang
- Nutritional Crop Physiology, Institute of Crop Science, University of HohenheimStuttgart, Germany
| | - York-Dieter Stierhof
- Zentrum für Molekularbiologie der Pflanzen, University of TübingenTübingen, Germany
| | - Uwe Ludewig
- Nutritional Crop Physiology, Institute of Crop Science, University of HohenheimStuttgart, Germany
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26
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Mohsin M, Ahmad A. Genetically-encoded nanosensor for quantitative monitoring of methionine in bacterial and yeast cells. Biosens Bioelectron 2014; 59:358-64. [DOI: 10.1016/j.bios.2014.03.066] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Revised: 03/12/2014] [Accepted: 03/31/2014] [Indexed: 01/22/2023]
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27
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Hamers D, van Voorst Vader L, Borst JW, Goedhart J. Development of FRET biosensors for mammalian and plant systems. PROTOPLASMA 2014; 251:333-347. [PMID: 24337770 DOI: 10.1007/s00709-013-0590-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 11/19/2013] [Indexed: 06/03/2023]
Abstract
Genetically encoded biosensors are increasingly used in visualising signalling processes in different organisms. Sensors based on green fluorescent protein technology are providing a great opportunity for using Förster resonance energy transfer (FRET) as a tool that allows for monitoring dynamic processes in living cells. The development of these FRET biosensors requires careful selection of fluorophores, substrates and recognition domains. In this review, we will discuss recent developments, strategies to create and optimise FRET biosensors and applications of FRET-based biosensors for use in the two major eukaryotic kingdoms and elaborate on different methods for FRET detection.
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Affiliation(s)
- Danny Hamers
- Laboratory of Biochemistry and Microspectroscopy Centre, Wageningen University, Wageningen, The Netherlands
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28
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Zhang C, Wei ZH, Ye BC. Imaging and tracing of intracellular metabolites utilizing genetically encoded fluorescent biosensors. Biotechnol J 2013; 8:1280-91. [DOI: 10.1002/biot.201300001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 08/02/2013] [Accepted: 08/26/2013] [Indexed: 12/11/2022]
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29
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Abstract
Bioprocess monitoring is used to track the progress of a cell culture and ensure that the product quality is maintained. Current schemes for monitoring metabolism rely on offline measurements of samples of the extracellular medium. However, in the era of synthetic biology, it is now possible to design and implement biosensors that consist of biological macromolecules and are able to report on the intracellular environment of cells. The use of fluorescent reporter signals allows non-invasive, non-destructive and online monitoring of the culture, which reduces the delay between measurement and any necessary intervention. The present mini-review focuses on protein-based biosensors that utilize FRET as the signal transduction mechanism. The mechanism of FRET, which utilizes the ratio of emission intensity at two wavelengths, has an inherent advantage of being ratiometric, meaning that small differences in the experimental set-up or biosensor expression level can be normalized away. This allows for more reliable quantitative estimation of the concentration of the target molecule. Existing FRET biosensors that are of potential interest to bioprocess monitoring include those developed for primary metabolites, redox potential, pH and product formation. For target molecules where a biosensor has not yet been developed, some candidate binding domains can be identified from the existing biological databases. However, the remaining challenge is to make the process of developing a FRET biosensor faster and more efficient.
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30
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Ozyurt C, Evran S, Telefoncu A. Development of a novel fluorescent protein construct by genetically fusing green fluorescent protein to the N-terminal of aspartate dehydrogenase. Biotechnol Appl Biochem 2013; 60:399-404. [PMID: 24033594 DOI: 10.1002/bab.1107] [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: 10/16/2012] [Accepted: 02/06/2013] [Indexed: 11/11/2022]
Abstract
We developed a fluorescent protein construct by genetically fusing green fluorescent protein (GFP) to aspartate dehydrogenase from Thermotoga maritima. The fusion protein was cloned, heterologously expressed in Escherichia coli cells, and purified by Ni-chelate affinity chromatography. It was then introduced into a measurement cuvette to monitor its fluorescence signal. Aspartate dehydrogenase functioned as the biorecognition element, and aspartate-induced conformational change was converted to a fluorescence signal by GFP. The recombinant protein responded to l-aspartate (l-Asp) linearly within the concentration range of 1-50 mM, and it was capable of giving a fluorescence signal in 1 Min. Although a linear response was also observed for l-Glu, the fluorescence signal was 2.7 times lower than that observed for l-Asp. In the present study, we describe two novelties: development of a genetically encoded fluorescent protein construct for monitoring of l-Asp in vitro, and employment of aspartate dehydrogenase scaffold as a biorecognition element. A few genetically encoded amino-acid biosensors have been described in the literature, but to our knowledge, a protein has not been constructed solely for determination of l-Asp. Periplasmic ligand binding proteins offer high binding affinity in the micromolar range, and they are frequently used as biorecognition elements. Instead of choosing a periplasmic l-Asp binding protein, we attempted to use the substrate specificity of aspartate dehydrogenase enzyme.
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Affiliation(s)
- Canan Ozyurt
- Department of Biochemistry, Faculty of Science, Ege University, Izmir, Turkey
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31
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Zhang C, Wei ZH, Ye BC. Quantitative monitoring of 2-oxoglutarate in Escherichia coli cells by a fluorescence resonance energy transfer-based biosensor. Appl Microbiol Biotechnol 2013; 97:8307-16. [PMID: 23893310 DOI: 10.1007/s00253-013-5121-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 06/07/2013] [Accepted: 07/10/2013] [Indexed: 11/25/2022]
Abstract
2-Oxoglutarate (2OG) is a metabolite from the highly conserved Krebs cycle and not only plays a critical role in metabolism but also acts as a signaling molecule in a variety of organisms. Environmental inorganic nitrogen is reduced to ammonium by microorganisms, whose metabolic pathways involve the conversion of 2OG to glutamate and glutamine. Tracking of 2OG in real time would be useful for studies on cell metabolism and signal transduction. Here, we developed a genetically encoded 2OG biosensor based on fluorescent resonance energy transfer by inserting the functional 2OG-binding domain GAF of the NifA protein between the fluorescence resonance energy transfer (FRET) pair YFP/CFP. The dynamic range of the sensors is 100 μM to 10 mM, which appeared identical to the physiological range observed in E. coli. We optimized the peptide lengths of the binding domain to obtain a sensor with a maximal ratio change of 0.95 upon 2OG binding and demonstrated the feasibility of this sensor for the visualization of metabolites both in vitro and in vivo.
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Affiliation(s)
- Chang Zhang
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
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32
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Mohsin M, Abdin MZ, Nischal L, Kardam H, Ahmad A. Genetically encoded FRET-based nanosensor for in vivo measurement of leucine. Biosens Bioelectron 2013; 50:72-7. [PMID: 23835220 DOI: 10.1016/j.bios.2013.06.028] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 05/31/2013] [Accepted: 06/11/2013] [Indexed: 01/08/2023]
Abstract
Besides fundamental role in protein synthesis, leucine has metabolic roles as energy substrates, precursors for synthesis of other amino acids and as a modulator of muscle protein synthesis via the insulin-signaling pathway. Leucine concentration in cell and tissue is temporally dynamic as the metabolism of leucine is regulated through multiple enzymes and transporters. Assessment of cell-type specific activities of transporters and enzymes by physical fractionation is extremely challenging. Therefore, a method of reporting leucine dynamics at the cellular level is highly desirable. Given this, we developed a series of genetically encoded nanosensors for real-time in vivo measurement of leucine at cellular level. A leucine binding periplasmic binding protein (LivK) of Escherichia coli K12 was flanked with CFP (cyan fluorescent protein) and YFP (yellow fluorescent protein) at N-terminus and C-terminus, respectively. The constructed nanosensors allowed in vitro determination of fluorescence resonance energy transfer (FRET) changes in a concentration-dependent manner. These sensors were found to be specific to leucine, and stable to pH-changes within a physiological range. Genetically encoded sensors can be targeted to a specific cell type, and allow dynamic measurement of leucine concentration in bacterial and yeast cells.
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Affiliation(s)
- Mohd Mohsin
- Molecular Ecology Laboratory, Department of Botany, Faculty of Science, Hamdard University, New Delhi 110062, India
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33
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Goers L, Kylilis N, Tomazou M, Yan Wen K, Freemont P, Polizzi K. Engineering Microbial Biosensors. METHODS IN MICROBIOLOGY 2013. [DOI: 10.1016/b978-0-12-417029-2.00005-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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34
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Masharina A, Reymond L, Maurel D, Umezawa K, Johnsson K. A Fluorescent Sensor for GABA and Synthetic GABAB Receptor Ligands. J Am Chem Soc 2012; 134:19026-34. [DOI: 10.1021/ja306320s] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Anastasiya Masharina
- Institute of Chemical
Sciences and Engineering (ISIC),
Institute of Bioengineering, NCCR in Chemical Biology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Luc Reymond
- Institute of Chemical
Sciences and Engineering (ISIC),
Institute of Bioengineering, NCCR in Chemical Biology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Damien Maurel
- Institute of Chemical
Sciences and Engineering (ISIC),
Institute of Bioengineering, NCCR in Chemical Biology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Keitaro Umezawa
- Institute of Chemical
Sciences and Engineering (ISIC),
Institute of Bioengineering, NCCR in Chemical Biology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Kai Johnsson
- Institute of Chemical
Sciences and Engineering (ISIC),
Institute of Bioengineering, NCCR in Chemical Biology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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35
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Okumoto S. Quantitative imaging using genetically encoded sensors for small molecules in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 70:108-17. [PMID: 22449046 DOI: 10.1111/j.1365-313x.2012.04910.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Quantitative imaging in live cells is a powerful method for monitoring the dynamics of biomolecules at an excellent spatio-temporal resolution. Such an approach, initially limited to a small number of substrates for which specific dyes were available, has become possible for a large number of biomolecules due to the development of genetically encoded, protein-based sensors. These sensors, which can be introduced into live cells through a transgenic approach, offer the benefits of quantitative imaging, with an extra advantage of non-invasiveness. In the past decade there has been a drastic expansion in the number of biomolecules for which genetically encoded sensors are available, and the functional properties of existing sensors are being improved at a dramatic pace. A number of technical improvements have now made the application of genetically encoded sensors in plants rather straightforward, and some of the sensors such as calcium indicator proteins have become standard analytical tools in many plant laboratories. The use of a handful of probes has already revealed an amazing specificity of cellular biomolecule dynamics in plants, which leads us to believe that there are many more discoveries to be made using genetically encoded sensors. In this short review, we will summarize the progress made in the past 15 years in the development in genetically encoded sensors, and highlight significant discoveries made in plant biology.
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Affiliation(s)
- Sakiko Okumoto
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA.
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Marvin JS, Schreiter ER, Echevarría IM, Looger LL. A genetically encoded, high-signal-to-noise maltose sensor. Proteins 2012; 79:3025-36. [PMID: 21989929 PMCID: PMC3265398 DOI: 10.1002/prot.23118] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We describe the generation of a family of high-signal-to-noise single-wavelength genetically encoded indicators for maltose. This was achieved by insertion of circularly permuted fluorescent proteins into a bacterial periplasmic binding protein (PBP), Escherichia coli maltodextrin-binding protein, resulting in a four-color family of maltose indicators. The sensors were iteratively optimized to have sufficient brightness and maltose-dependent fluorescence increases for imaging, under both one- and two-photon illumination. We demonstrate that maltose affinity of the sensors can be tuned in a fashion largely independent of the fluorescent readout mechanism. Using literature mutations, the binding specificity could be altered to moderate sucrose preference, but with a significant loss of affinity. We use the soluble sensors in individual E. coli bacteria to observe rapid maltose transport across the plasma membrane, and membrane fusion versions of the sensors on mammalian cells to visualize the addition of maltose to extracellular media. The PBP superfamily includes scaffolds specific for a number of analytes whose visualization would be critical to the reverse engineering of complex systems such as neural networks, biosynthetic pathways, and signal transduction cascades. We expect the methodology outlined here to be useful in the development of indicators for many such analytes.
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Affiliation(s)
- Jonathan S Marvin
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA.
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Okumoto S, Jones A, Frommer WB. Quantitative imaging with fluorescent biosensors. ANNUAL REVIEW OF PLANT BIOLOGY 2012; 63:663-706. [PMID: 22404462 DOI: 10.1146/annurev-arplant-042110-103745] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Molecular activities are highly dynamic and can occur locally in subcellular domains or compartments. Neighboring cells in the same tissue can exist in different states. Therefore, quantitative information on the cellular and subcellular dynamics of ions, signaling molecules, and metabolites is critical for functional understanding of organisms. Mass spectrometry is generally used for monitoring ions and metabolites; however, its temporal and spatial resolution are limited. Fluorescent proteins have revolutionized many areas of biology-e.g., fluorescent proteins can report on gene expression or protein localization in real time-yet promoter-based reporters are often slow to report physiologically relevant changes such as calcium oscillations. Therefore, novel tools are required that can be deployed in specific cells and targeted to subcellular compartments in order to quantify target molecule dynamics directly. We require tools that can measure enzyme activities, protein dynamics, and biophysical processes (e.g., membrane potential or molecular tension) with subcellular resolution. Today, we have an extensive suite of tools at our disposal to address these challenges, including translocation sensors, fluorescence-intensity sensors, and Förster resonance energy transfer sensors. This review summarizes sensor design principles, provides a database of sensors for more than 70 different analytes/processes, and gives examples of applications in quantitative live cell imaging.
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Affiliation(s)
- Sakiko Okumoto
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA
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In vivo biochemistry: quantifying ion and metabolite levels in individual cells or cultures of yeast. Biochem J 2011; 438:1-10. [PMID: 21793803 DOI: 10.1042/bj20110428] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Over the past decade, we have learned that cellular processes, including signalling and metabolism, are highly compartmentalized, and that relevant changes in metabolic state can occur at sub-second timescales. Moreover, we have learned that individual cells in populations, or as part of a tissue, exist in different states. If we want to understand metabolic processes and signalling better, it will be necessary to measure biochemical and biophysical responses of individual cells with high temporal and spatial resolution. Fluorescence imaging has revolutionized all aspects of biology since it has the potential to provide information on the cellular and subcellular distribution of ions and metabolites with sub-second time resolution. In the present review we summarize recent progress in quantifying ions and metabolites in populations of yeast cells as well as in individual yeast cells with the help of quantitative fluorescent indicators, namely FRET metabolite sensors. We discuss the opportunities and potential pitfalls and the controls that help preclude misinterpretation.
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Abstract
Background Glutamine is one of the primary amino acids in nitrogen assimilation and often the most abundant amino acid in plant roots. To monitor this important metabolite, a novel genetically encoded fluorescent FRET-reporter was constructed and expressed in Arabidopsis thaliana. As a candidate for the glutamine fluxes, the root tip localized, putative amino acid transporter CAT8 was analyzed and heterologously expressed in yeast and oocytes. Principal Findings Rapid and reversible in vivo fluorescence changes were observed in reporter-expressing root tips upon exposure and removal of glutamine. FRET changes were detected at acid and neutral pH and in the presence of a protonophore, suggesting that part of the glutamine fluxes were independent of the pH. The putative amino acid transporter CAT8 transported glutamine, had a half maximal activity at ∼100 µM and the transport was independent of external pH. CAT8 localized not only to the plasma membrane, but additionally to the tonoplast, when tagged with GFP. Ultrastructural analysis confirmed this dual localization and additionally identified CAT8 in membranes of autophagosomes. Loss-of function of CAT8 did not affect growth in various conditions, but over-expressor plants had increased sensitivity to a structural substrate analog, the glutamine synthetase inhibitor L-methionine sulfoximine. Conclusions The combined data suggest that proton-independent glutamine facilitators exist in root tips.
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Easun TL, Alsindi WZ, Deppermann N, Towrie M, Ronayne KL, Sun XZ, Ward MD, George MW. Luminescence and Time-Resolved Infrared Study of Dyads Containing (Diimine)Ru(4,4′-diethylamido-2,2′-bipyridine)2 and (Diimine)Ru(CN)4 Moieties: Solvent-Induced Reversal of the Direction of Photoinduced Energy-Transfer. Inorg Chem 2009; 48:8759-70. [DOI: 10.1021/ic900924w] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Timothy L. Easun
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Wassim Z. Alsindi
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K
| | - Nina Deppermann
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Michael Towrie
- Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Kate L. Ronayne
- Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Xue-Zhong Sun
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K
| | - Michael D. Ward
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Michael W. George
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K
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Chapter 10 FRET and FLIM applications in plants. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s0075-7535(08)00010-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
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Niittylae T, Chaudhuri B, Sauer U, Frommer WB. Comparison of quantitative metabolite imaging tools and carbon-13 techniques for fluxomics. Methods Mol Biol 2009; 553:355-72. [PMID: 19588116 DOI: 10.1007/978-1-60327-563-7_19] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The recent development of analytic technologies allows fast analysis of metabolism in real time. Fluxomics aims to define the genes involved in regulation of flux through a metabolic or signaling pathway. Flux through a metabolic or signaling pathway is determined by the activity of its individual components; regulation can occur at many levels, including transcriptional, posttranslational, and allosteric levels. Currently two technologies are used to monitor fluxes. The first is pulse labeling of the organism with a tracer such as C13, followed by mass spectrometric analysis of the partitioning of label into different compounds. The second approach is based on the use of flux sensors, proteins that respond with a conformational change to ligand binding. Fluorescence resonance energy transfer (FRET) detects the conformational change and serves as a proxy for ligand concentration. Both methods provide high time resolution. In contrast to mass spectrometry assays, FRET nanosensors monitor only a single compound, but the advantage of FRET nanosensors is that they yield data with cellular and subcellular resolution.
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Affiliation(s)
- Totte Niittylae
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA
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Easun TL, Alsindi WZ, Towrie M, Ronayne KL, Sun XZ, Ward MD, George MW. Photoinduced Energy Transfer in a Conformationally Flexible Re(I)/Ru(II) Dyad Probed by Time-Resolved Infrared Spectroscopy: Effects of Conformation and Spatial Localization of Excited States. Inorg Chem 2008; 47:5071-8. [DOI: 10.1021/ic702005w] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Timothy L. Easun
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K., School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K., and Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Wassim Z. Alsindi
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K., School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K., and Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Michael Towrie
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K., School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K., and Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Kate L. Ronayne
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K., School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K., and Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Xue-Zhong Sun
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K., School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K., and Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Michael D. Ward
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K., School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K., and Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Michael W. George
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K., School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K., and Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
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Funck D, Stadelhofer B, Koch W. Ornithine-delta-aminotransferase is essential for arginine catabolism but not for proline biosynthesis. BMC PLANT BIOLOGY 2008; 8:40. [PMID: 18419821 PMCID: PMC2377265 DOI: 10.1186/1471-2229-8-40] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Accepted: 04/17/2008] [Indexed: 05/18/2023]
Abstract
BACKGROUND Like many other plant species, Arabidopsis uses arginine (Arg) as a storage and transport form of nitrogen, and proline (Pro) as a compatible solute in the defence against abiotic stresses causing water deprivation. Arg catabolism produces ornithine (Orn) inside mitochondria, which was discussed controversially as a precursor for Pro biosynthesis, alternative to glutamate (Glu). RESULTS We show here that ornithine-delta-aminotransferase (deltaOAT, At5g46180), the enzyme converting Orn to pyrroline-5-carboxylate (P5C), is localised in mitochondria and is essential for Arg catabolism. Wildtype plants could readily catabolise supplied Arg and Orn and were able to use these amino acids as the only nitrogen source. Deletion mutants of deltaOAT, however, accumulated urea cycle intermediates when fed with Arg or Orn and were not able to utilize nitrogen provided as Arg or Orn. Utilisation of urea and stress induced Pro accumulation were not affected in T-DNA insertion mutants with a complete loss of deltaOAT expression. CONCLUSION Our findings indicate that deltaOAT feeds P5C exclusively into the catabolic branch of Pro metabolism, which yields Glu as an end product. Conversion of Orn to Glu is an essential route for recovery of nitrogen stored or transported as Arg. Pro biosynthesis occurs predominantly or exclusively via the Glu pathway in Arabidopsis and does not depend on Glu produced by Arg and Orn catabolism.
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Affiliation(s)
- Dietmar Funck
- Department of Plant Physiology and Biochemistry, Biology Section, University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
| | - Bettina Stadelhofer
- ZMBP Plant Physiology, University of Tübingen, Auf der Morgenstelle 1, 72076 Tübingen, Germany
| | - Wolfgang Koch
- ZMBP Plant Physiology, University of Tübingen, Auf der Morgenstelle 1, 72076 Tübingen, Germany
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Tian L, Looger LL. Genetically encoded fluorescent sensors for studying healthy and diseased nervous systems. DRUG DISCOVERY TODAY. DISEASE MODELS 2008; 5:27-35. [PMID: 19461949 PMCID: PMC2651031 DOI: 10.1016/j.ddmod.2008.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Neurons and glia are functionally organized into circuits and higher-order structures via synaptic connectivity, well-orchestrated molecular signaling, and activity-dependent refinement. Such organization allows the precise information processing required for complex behaviors. Disruption of nervous systems by genetic deficiency or events such as trauma or environmental exposure may produce a diseased state in which certain aspects of inter-neuron signaling are impaired. Optical imaging techniques allow the direct visualization of individual neurons in a circuit environment. Imaging probes specific for given biomolecules may help elucidate their contribution to proper circuit function. Genetically encoded sensors can visualize trafficking of particular molecules in defined neuronal populations, non-invasively in intact brain or reduced preparations. Sensor analysis in healthy and diseased brains may reveal important differences and shed light on the development and progression of nervous system disorders. We review the field of genetically encoded sensors for molecules and cellular events, and their potential applicability to the study of nervous system disease.
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Affiliation(s)
- Lin Tian
- Howard Hughes Medical Institute Janelia Farm Research Campus, 19700 Helix Dr. Ashburn, VA, 20194, USA
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Okumoto S, Takanaga H, Frommer WB. Quantitative imaging for discovery and assembly of the metabo-regulome. THE NEW PHYTOLOGIST 2008; 180:271-295. [PMID: 19138219 PMCID: PMC2663047 DOI: 10.1111/j.1469-8137.2008.02611.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Little is known about regulatory networks that control metabolic flux in plant cells. Detailed understanding of regulation is crucial for synthetic biology. The difficulty of measuring metabolites with cellular and subcellular precision is a major roadblock. New tools have been developed for monitoring extracellular, cytosolic, organellar and vacuolar ion and metabolite concentrations with a time resolution of milliseconds to hours. Genetically encoded sensors allow quantitative measurement of steady-state concentrations of ions, signaling molecules and metabolites and their respective changes over time. Fluorescence resonance energy transfer (FRET) sensors exploit conformational changes in polypeptides as a proxy for analyte concentrations. Subtle effects of analyte binding on the conformation of the recognition element are translated into a FRET change between two fused green fluorescent protein (GFP) variants, enabling simple monitoring of analyte concentrations using fluorimetry or fluorescence microscopy. Fluorimetry provides information averaged over cell populations, while microscopy detects differences between cells or populations of cells. The genetically encoded sensors can be targeted to subcellular compartments or the cell surface. Confocal microscopy ultimately permits observation of gradients or local differences within a compartment. The FRET assays can be adapted to high-throughput analysis to screen mutant populations in order to systematically identify signaling networks that control individual steps in metabolic flux.
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Affiliation(s)
- Sakiko Okumoto
- Plant Pathology, Physiology, and Weed Science Department, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Hitomi Takanaga
- Carnegie Institution for Science, Department of Plant Biology, 260 Panama St., Stanford, CA 94305, USA
| | - Wolf B. Frommer
- Carnegie Institution for Science, Department of Plant Biology, 260 Panama St., Stanford, CA 94305, USA
- Joint Bioenergy Institute, Feedstocks Division, Emerystation East, 5885 Hollis Street Emeryville, CA 94608, USA
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