1
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Allert MJ, Hellinga HW. Discovery of Thermostable, Fluorescently Responsive Glucose Biosensors by Structure-Assisted Function Extrapolation. Biochemistry 2022; 61:276-293. [PMID: 35084821 DOI: 10.1021/acs.biochem.1c00738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Accurate assignment of protein function from sequence remains a fascinating and difficult challenge. The periplasmic-binding protein (PBP) superfamily present an interesting case of function prediction because they are both ubiquitous in prokaryotes and tend to diversify through gene duplication "explosions" that can lead to large numbers of paralogs in a genome. An engineered version of the moderately thermostable glucose-binding PBP from Escherichia coli has been used successfully as a reagentless fluorescent biosensor both in vitro and in vivo. To develop more robust sensors that meet the challenges of real-world applications, we report the discovery of thermostable homologues that retain a glucose-mediated conformationally coupled fluorescence response. Accurately identifying a glucose-binding PBP homologue among closely related paralogs is challenging. We demonstrate that a structure-based method that filters sequences by residues that bind glucose in an archetype structure is highly effective. Using fully sequenced bacterial genomes, we found that this filter reduced high paralog numbers to single hits in a genome, consistent with the accurate separation of glucose binding from other functions. We expressed engineered proteins for eight homologues, chosen to represent different degrees of sequence identity, and tested their glucose-mediated fluorescence responses. We accurately predicted the presence of glucose binding down to 31% sequence identity. We have also successfully identified suitable candidates for next-generation robust, fluorescent glucose sensors.
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Affiliation(s)
- Malin J Allert
- Department of Biochemistry, Duke University Medical Center, Box 3711, Durham, North Carolina 27710, United States
| | - Homme W Hellinga
- Department of Biochemistry, Duke University Medical Center, Box 3711, Durham, North Carolina 27710, United States
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2
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Pang Z, Sokolov M, Kubař T, Elstner M. Unravelling the mechanism of glucose binding in a protein-based fluorescence probe: molecular dynamics simulation with a tailor-made charge model. Phys Chem Chem Phys 2022; 24:2441-2453. [PMID: 35019922 DOI: 10.1039/d1cp03733a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Fluorophores linked to the glucose/galactose-binding protein (GGBP) are a promising class of glucose sensors with potential application in medical devices for diabetes patients. Several different fluorophores at different positions in the protein were tested experimentally so far, but a deeper molecular understanding of their function is still missing. In this work, we use molecular dynamics simulations to investigate the mechanism of glucose binding in the GGBP-Badan triple mutant and make a comparison to the GGBP wild-type protein. The aim is to achieve a detailed molecular understanding of changes in the glucose binding site due to the mutations and their effect on glucose binding. Free simulations give an insight into the changes of the hydrogen-bonding network in the active site and into the mechanisms of glucose binding. Additionally, metadynamics simulations for wild type and mutant unravel the energetics of binding/unbinding in these proteins. Computed free energies for the opening of the binding pocket for the wild-type and the mutant agree well with the experimental data. Further, the simulations also give an insight into the changes of the chromophore conformations upon glucose binding, which can help to understand fluorescence changes. Therefore, the molecular details unravelled in this work may support effective optimisation strategies for the construction of more efficient glucose sensors.
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Affiliation(s)
- Ziwei Pang
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany.
| | - Monja Sokolov
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany.
| | - Tomáš Kubař
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany.
| | - Marcus Elstner
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany. .,Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
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3
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Keller JP, Marvin JS, Lacin H, Lemon WC, Shea J, Kim S, Lee RT, Koyama M, Keller PJ, Looger LL. In vivo glucose imaging in multiple model organisms with an engineered single-wavelength sensor. Cell Rep 2021; 35:109284. [PMID: 34161775 DOI: 10.1016/j.celrep.2021.109284] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 03/06/2020] [Accepted: 06/01/2021] [Indexed: 12/23/2022] Open
Abstract
Glucose is arguably the most important molecule in metabolism, and its dysregulation underlies diabetes. We describe a family of single-wavelength genetically encoded glucose sensors with a high signal-to-noise ratio, fast kinetics, and affinities varying over four orders of magnitude (1 μM to 10 mM). The sensors allow mechanistic characterization of glucose transporters expressed in cultured cells with high spatial and temporal resolution. Imaging of neuron/glia co-cultures revealed ∼3-fold faster glucose changes in astrocytes. In larval Drosophila central nervous system explants, intracellular neuronal glucose fluxes suggested a rostro-caudal transport pathway in the ventral nerve cord neuropil. In zebrafish, expected glucose-related physiological sequelae of insulin and epinephrine treatments were directly visualized. Additionally, spontaneous muscle twitches induced glucose uptake in muscle, and sensory and pharmacological perturbations produced large changes in the brain. These sensors will enable rapid, high-resolution imaging of glucose influx, efflux, and metabolism in behaving animals.
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Affiliation(s)
- Jacob P Keller
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Haluk Lacin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - William C Lemon
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Jamien Shea
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Soomin Kim
- Harvard Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard Medical School, Brigham and Women's Hospital, Cambridge, MA, USA
| | - Richard T Lee
- Harvard Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard Medical School, Brigham and Women's Hospital, Cambridge, MA, USA; The Cardiovascular Division, Department of Medicine, Harvard Medical School, Brigham and Women's Hospital, Cambridge, MA, USA
| | - Minoru Koyama
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Philipp J Keller
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
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4
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Lin KY, Hin Lam C, Lin XH, Hsu JI, Fan SY, Gupta NK, Lin YC, Khoon Tee B, Li JP, Chen JK, Tan KT. Improved Stabilities of Labeling Probes for the Selective Modification of Endogenous Proteins in Living Cells and In Vivo. Chem Asian J 2021; 16:937-948. [PMID: 33629493 DOI: 10.1002/asia.202100060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/23/2021] [Indexed: 01/24/2023]
Abstract
To date, various affinity-based protein labeling probes have been developed and applied in biological research to modify endogenous proteins in cell lysates and on the cell surface. However, the reactive groups on the labeling probes are also the cause of probe instability and nonselective labeling in a more complex environment, e. g., intracellular and in vivo. Here, we show that labeling probes composed of a sterically stabilized difluorophenyl pivalate can achieve efficient and selective labeling of endogenous proteins on the cell surface, inside living cells and in vivo. As compared with the existing protein labeling probes, probes with the difluorophenyl pivalate exhibit several advantages, including long-term stability in stock solutions, resistance to enzymatic hydrolysis and can be customized easily with diverse fluorophores and protein ligands. With this probe design, endogenous hypoxia biomarker in living cells and nude mice were successfully labeled and validated by in vivo, ex vivo, and immunohistochemistry imaging.
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Affiliation(s)
- Kuan-Yu Lin
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan
| | - Chak Hin Lam
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan
| | - Xin-Hui Lin
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan
| | - Jung-I Hsu
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan
| | - Syuan-Yun Fan
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan
| | - Nitesh K Gupta
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan
| | - Yu-Chun Lin
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan
| | - Boon Khoon Tee
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan
| | - Jui-Ping Li
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, 35053, Taiwan
| | - Jen-Kun Chen
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, 35053, Taiwan
| | - Kui-Thong Tan
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan.,Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan.,Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, 807, Taiwan
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5
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Yang M, Tang Y, Weng J, Liu Z, Wang W. The Role of Calcium in Regulating the Conformational Dynamics of d-Galactose/d-Glucose-Binding Protein Revealed by Markov State Model Analysis. J Chem Inf Model 2021; 61:891-900. [PMID: 33445873 DOI: 10.1021/acs.jcim.0c01119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The d-glucose/d-galactose-binding protein (GGBP) from Escherichia coli is a substrate-binding protein (SBP) associated with sugar transport and chemotaxis. It is also a calcium-binding protein, which makes it unique in the SBP family. However, the functional importance of Ca2+ binding is not fully understood. Here, the calcium-dependent properties of GGBP were explored by all-atom molecular dynamics simulations and Markov state model (MSM) analysis as well as single-molecule Förster resonance energy transfer (smFRET) measurements. In agreement with previous experimental studies, we observed the structure stabilization effect of Ca2+ binding on the C-terminal domain of GGBP, especially the Ca2+-binding site. Interestingly, the MSMs of calcium-depleted GGBP and calcium-bound GGBP (GGBP/Ca2+) demonstrate that Ca2+ greatly stabilizes the open conformation, and smFRET measurements confirmed this result. Further analysis reveals that Ca2+ binding disturbs the local hydrogen bonding interactions and the conformational dynamics of the hinge region, thereby weakening the long-range interdomain correlations to favor the open conformation. These results suggest an active regulatory role of Ca2+ binding in GGBP, which finely tunes the conformational distribution. The work sheds new light on the study of calcium-binding proteins in prokaryotes.
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Affiliation(s)
- Maohua Yang
- Department of Chemistry, Multiscale Research Institute of Complex Systems and Institute of Biomedical Sciences, Fudan University, Shanghai 200438, China
| | - Yegen Tang
- Department of Chemistry, Multiscale Research Institute of Complex Systems and Institute of Biomedical Sciences, Fudan University, Shanghai 200438, China
| | - Jingwei Weng
- Department of Chemistry, Multiscale Research Institute of Complex Systems and Institute of Biomedical Sciences, Fudan University, Shanghai 200438, China
| | - Zhijun Liu
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - Wenning Wang
- Department of Chemistry, Multiscale Research Institute of Complex Systems and Institute of Biomedical Sciences, Fudan University, Shanghai 200438, China
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6
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Chan HJ, Lin XH, Fan SY, Ru Hwu J, Tan KT. Rapid and Selective Labeling of Endogenous Transmembrane Proteins in Living Cells with a Difluorophenyl Ester Affinity-Based Probe. Chem Asian J 2020; 15:3416-3420. [PMID: 32931625 DOI: 10.1002/asia.202001049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Indexed: 12/28/2022]
Abstract
The long-term stability of affinity-based protein labeling probes is crucial to obtain reproducible protein labeling results. However, highly stable probes generally suffer from low protein labeling efficiency and pose significant challenges when labeling low abundance native proteins in living cells. In this paper, we report that protein labeling probes based on an ortho-difluorophenyl ester reactive module exhibit long-term stability in DMSO stock solution and aqueous buffer, yet they can undergo rapid and selective labeling of native proteins. This novel electrophile can be customized with a wide range of different protein ligands and is particularly well-suited for the labeling and imaging of transmembrane proteins. With this probe design, the identity and relative levels of basal and hypoxia-induced transmembrane carbonic anhydrases were revealed by live cell imaging and in-gel fluorescence analysis. We believe that the extension of this difluorophenyl ester reactive module would allow for the specific labeling of various endogenous membrane proteins, facilitating in-depth studies of their distribution and functions in biological processes.
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Affiliation(s)
- Hsin-Ju Chan
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan (Republic of China
| | - Xin-Hui Lin
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan (Republic of China
| | - Syuan-Yun Fan
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan (Republic of China
| | - Jih Ru Hwu
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan (Republic of China.,Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan (Republic of China
| | - Kui-Thong Tan
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan (Republic of China.,Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu, 30013, Taiwan (Republic of China.,Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, 807, Taiwan (Republic of China
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7
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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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8
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Chandrasekaran N, Matheswaran M. Unique Nonenzymatic Glucose Sensor Using a Hollow-Shelled Triple Oxide Mn-Cu-Al Nanocomposite. ACS OMEGA 2020; 5:23502-23509. [PMID: 32984668 PMCID: PMC7512457 DOI: 10.1021/acsomega.0c00417] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Glucose monitoring devices for diabetes mellitus, which is a worldwide significant health issue, have attracted attention of many researchers. Herein, we report a hollow Mn-Cu-Al oxide nanocomposite (HMCA) by a microwave-assisted technique showing excellent sensing abilities toward glucose. Also, it possesses a superb supercapacitor activity described in our previous paper. The sensitivity value of the nanocomposite is 2.194 mA mM-1 cm-2 with a low detection limit of 0.43 μM (S/N = 3). The high sensitivity and low detection limit were the results of the large surface area of the nanocomposite and the redox nature of CuO and MnO2. It shows a selective detection of glucose levels in blood serum. The hollow nanocomposite has been useful for monitoring the glucose level in blood serum and holds great potential for diabetes mellitus and clinical diagnosis.
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Affiliation(s)
| | - Manickam Matheswaran
- Department
of Chemical Engineering, National Institute
of Technology Tiruchirappalli, Tiruchirappalli 620015, India
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9
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Cycloserine enantiomers are reversible inhibitors of human alanine:glyoxylate aminotransferase: implications for Primary Hyperoxaluria type 1. Biochem J 2020; 476:3751-3768. [PMID: 31794008 DOI: 10.1042/bcj20190507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 11/12/2019] [Accepted: 12/03/2019] [Indexed: 12/14/2022]
Abstract
Peroxisomal alanine:glyoxylate aminotransferase (AGT) is responsible for glyoxylate detoxification in human liver and utilizes pyridoxal 5'-phosphate (PLP) as coenzyme. The deficit of AGT leads to Primary Hyperoxaluria Type I (PH1), a rare disease characterized by calcium oxalate stones deposition in the urinary tract as a consequence of glyoxylate accumulation. Most missense mutations cause AGT misfolding, as in the case of the G41R, which induces aggregation and proteolytic degradation. We have investigated the interaction of wild-type AGT and the pathogenic G41R variant with d-cycloserine (DCS, commercialized as Seromycin), a natural product used as a second-line treatment of multidrug-resistant tuberculosis, and its synthetic enantiomer l-cycloserine (LCS). In contrast with evidences previously reported on other PLP-enzymes, both ligands are AGT reversible inhibitors showing inhibition constants in the micromolar range. While LCS undergoes half-transamination generating a ketimine intermediate and behaves as a classical competitive inhibitor, DCS displays a time-dependent binding mainly generating an oxime intermediate. Using a mammalian cellular model, we found that DCS, but not LCS, is able to promote the correct folding of the G41R variant, as revealed by its increased specific activity and expression as a soluble protein. This effect also translates into an increased glyoxylate detoxification ability of cells expressing the variant upon treatment with DCS. Overall, our findings establish that DCS could play a role as pharmacological chaperone, thus suggesting a new line of intervention against PH1 based on a drug repositioning approach. To a widest extent, this strategy could be applied to other disease-causing mutations leading to AGT misfolding.
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10
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Ko W, Kumar R, Kim S, Lee HS. Construction of Bacterial Cells with an Active Transport System for Unnatural Amino Acids. ACS Synth Biol 2019; 8:1195-1203. [PMID: 30971082 DOI: 10.1021/acssynbio.9b00076] [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] [Indexed: 12/28/2022]
Abstract
Engineered organisms with an expanded genetic code have attracted much attention in chemical and synthetic biology research. In this work, engineered bacterial organisms with enhanced unnatural amino acid (UAA) uptake abilities were developed by screening periplasmic binding protein (PBP) mutants for recognition of UAAs. A FRET-based assay was used to identify a mutant PBP (LBP-AEL) with excellent binding affinity ( Kd ≈ 500 nM) to multiple UAAs from 37 mutants. Bacterial cells expressing LBP-AEL showed up to 5-fold enhanced uptake of UAAs, which was determined by genetic incorporation of UAAs into a green fluorescent protein and measuring UAA concentration in cell lysates. To the best of our knowledge, this work is the first report of engineering cellular uptake of UAAs and could provide an impetus for designing advanced unnatural organisms with an expanded genetic code, which function with the efficiency comparable to that of natural organisms. The system would be useful to increase mutant protein yield from lower concentrations of UAAs for industrial and large-scale applications. In addition, the techniques used in this report such as the sensor design and the measurement of UAA concentration in cell lysates could be useful for other biochemical applications.
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Affiliation(s)
- Wooseok Ko
- Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea
| | - Rahul Kumar
- Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea
| | - Sanggil Kim
- Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea
| | - Hyun Soo Lee
- Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea
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11
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Kiyonaka S, Sakamoto S, Wakayama S, Morikawa Y, Tsujikawa M, Hamachi I. Ligand-Directed Chemistry of AMPA Receptors Confers Live-Cell Fluorescent Biosensors. ACS Chem Biol 2018; 13:1880-1889. [PMID: 29437380 DOI: 10.1021/acschembio.7b01042] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AMPA-type glutamate receptors (AMPARs) mediate fast excitatory synaptic transmission in the central nervous system. Dysregulation of AMPAR function is associated with many kinds of neurological, neurodegenerative, and psychiatric disorders. As a result, molecules capable of controlling AMPAR functions are potential therapeutic agents. Fluorescent semisynthetic biosensors have attracted considerable interest for the discovery of ligands selectively acting on target proteins. Given the large protein complex formation of AMPARs in live cells, biosensors using full-length AMPARs retaining original functionality are ideal for drug screening. Here, we demonstrate that fluorophore-labeled AMPARs prepared by ligand-directed acyl imidazole chemistry can act as turn-on fluorescent biosensors for AMPAR ligands in living cells. These biosensors selectively detect orthosteric ligands of AMPARs among the glutamate receptor family. Notably, the dissociation constants of agonists and antagonists for AMPARs were determined in live cells, which revealed that the ligand-binding properties of AMPARs to agonists are largely different in living cells, compared with noncellular conditions. We also show that these sensors can be applied to detecting allosteric modulators or subunit-selective ligands of AMPARs. Thus, our protein-based biosensors can be useful for discovering pharmaceutical agents to treat AMPAR-related neurological disorders.
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Affiliation(s)
- Shigeki Kiyonaka
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Seiji Sakamoto
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Sho Wakayama
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Yuma Morikawa
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Muneo Tsujikawa
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Itaru Hamachi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
- CREST(Core Research for Evolutional Science and Technology, JST), Chiyodaku, Tokyo, 102-0075, Japan
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12
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Ko W, Kim S, Lee HS. Engineering a periplasmic binding protein for amino acid sensors with improved binding properties. Org Biomol Chem 2018; 15:8761-8769. [PMID: 28994436 DOI: 10.1039/c7ob02165h] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Periplasmic binding proteins (PBPs) are members of a widely distributed protein superfamily found in bacteria and archaea, and are involved in the cellular uptake of solutes. In this report, a leucine-binding PBP was engineered to detect l-Leu based on a fluorescence resonance energy transfer (FRET) change upon ligand binding. A fluorescent unnatural amino acid, l-(7-hydroxycoumarin-4-yl)ethylglycine (CouA), was genetically incorporated into the protein as a FRET donor, and a yellow fluorescent protein (YFP) was fused with its N-terminus as a FRET acceptor. When CouA was incorporated into position 178, the sensor protein showed a 2.5-fold increase in the FRET ratio. Protein engineering significantly improved its substrate specificity, showing minimal changes in the FRET ratio with the other 19 natural amino acids and d-Leu. Further modification increased the sensitivity of the sensor protein (14-fold) towards l-Leu, and it recognized l-Met as well with moderate binding affinity. Selected mutant sensors were used to measure concentrations of l-Leu in a biological sample (fetal bovine serum) and to determine the optical purity of Leu and Met. This FRET-based sensor design strategy allowed us to easily manipulate the natural receptor to improve its binding affinity and specificity and to recognize other natural molecules, which are not recognized by the wild-type receptor. The design strategy can be applied to other natural receptors, enabling engineering receptors that sense biochemically interesting molecules.
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Affiliation(s)
- Wooseok Ko
- Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea.
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13
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Nakano S, Tamura T, Das RK, Nakata E, Chang YT, Morii T. A Diversity-Oriented Library of Fluorophore-Modified Receptors Constructed from a Chemical Library of Synthetic Fluorophores. Chembiochem 2017; 18:2212-2216. [PMID: 28879678 DOI: 10.1002/cbic.201700403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Indexed: 12/16/2022]
Abstract
The practical application of biosensors can be determined by evaluating the sensing ability of fluorophore-modified derivatives of a receptor with appropriate recognition characteristics for target molecules. One of the key determinants for successfully obtaining a useful biosensor is wide variation in the fluorophores attached to a given receptor. Thus, using a larger fluorophore-modified receptor library provides a higher probability of obtaining a practically useful biosensor. However, no effective method has yet been developed for constructing such a diverse library of fluorophore-modified receptors. Herein, we report a method for constructing fluorophore-modified receptors by using a chemical library of synthetic fluorophores with a thiol-reactive group. This library was converted into a library of fluorophore-modified adenosine-binding ribonucleopeptide (RNP) receptors by introducing the fluorophores to the Rev peptide of the RNP complex by alkylation of the thiol group. This method enabled the construction of 263 fluorophore-modified ATP-binding RNP receptors and allowed the selection of suitable receptor-based fluorescent sensors that target ATP.
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Affiliation(s)
- Shun Nakano
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Tomoki Tamura
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Raj Kumar Das
- Bharat Petroleum Corporation Ltd., Corporate R&D Centre, Plot No. 2 A, Udyog Kendra, Surajpur Industrial Area, Greater Noida, 201 306, India
| | - Eiji Nakata
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Young-Tae Chang
- Department of Chemistry and MedChem Program of Life Sciences, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.,Department of Chemistry, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, Korea
| | - Takashi Morii
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011, Japan
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Fonin AV, Golikova AD, Zvereva IA, D'Auria S, Staiano M, Uversky VN, Kuznetsova IM, Turoverov KK. Osmolyte-Like Stabilizing Effects of Low GdnHCl Concentrations on d-Glucose/d-Galactose-Binding Protein. Int J Mol Sci 2017; 18:E2008. [PMID: 28925982 PMCID: PMC5618657 DOI: 10.3390/ijms18092008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 09/14/2017] [Accepted: 09/16/2017] [Indexed: 11/16/2022] Open
Abstract
The ability of d-glucose/d-galactose-binding protein (GGBP) to reversibly interact with its ligands, glucose and galactose, makes this protein an attractive candidate for sensing elements of glucose biosensors. This potential is largely responsible for attracting researchers to study the conformational properties of this protein. Previously, we showed that an increase in the fluorescence intensity of the fluorescent dye 6-bromoacetyl-2-dimetylaminonaphtalene (BADAN) is linked to the holo-form of the GGBP/H152C mutant in solutions containing sub-denaturing concentrations of guanidine hydrochloride (GdnHCl). It was hypothesized that low GdnHCl concentrations might lead to compaction of the protein, thereby facilitating ligand binding. In this work, we utilize BADAN fluorescence spectroscopy, intrinsic protein UV fluorescence spectroscopy, and isothermal titration calorimetry (ITC) to show that the sub-denaturing GdnHCl concentrations possess osmolyte-like stabilizing effects on the structural dynamics, conformational stability, and functional activity of GGBP/H152C and the wild type of this protein (wtGGBP). Our data are consistent with the model where low GdnHCl concentrations promote a shift in the dynamic distribution of the protein molecules toward a conformational ensemble enriched in molecules with a tighter structure and a more closed conformation. This promotes the increase in the configurational complementarity between the protein and glucose molecules that leads to the increase in glucose affinity in both GGBP/H152C and wtGGBP.
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Affiliation(s)
- Alexander V Fonin
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, 194064 St. Petersburg, Russia.
| | - Alexandra D Golikova
- Saint Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia.
| | - Irina A Zvereva
- Saint Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia.
| | - Sabato D'Auria
- CNR, Institute of Food Science, via Roma 64, 83100 Avellino, Italy.
| | - Maria Staiano
- CNR, Institute of Food Science, via Roma 64, 83100 Avellino, Italy.
| | - Vladimir N Uversky
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA.
| | - Irina M Kuznetsova
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, 194064 St. Petersburg, Russia.
| | - Konstantin K Turoverov
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, 194064 St. Petersburg, Russia.
- Department of Biophysics, Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya av. 29, 195251 St. Petersburg, Russia.
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15
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Preformulation Characterization, Stabilization, and Formulation Design for the Acrylodan-Labeled Glucose-Binding Protein SM4-AC. J Pharm Sci 2017; 106:1197-1210. [DOI: 10.1016/j.xphs.2017.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/20/2016] [Accepted: 01/03/2017] [Indexed: 11/18/2022]
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16
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Donaldson T, Iozzino L, Deacon LJ, Billones H, Ausili A, D'Auria S, Dattelbaum JD. Engineering a switch-based biosensor for arginine using a Thermotoga maritima periplasmic binding protein. Anal Biochem 2017; 525:60-66. [PMID: 28259516 DOI: 10.1016/j.ab.2017.02.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/26/2017] [Accepted: 02/28/2017] [Indexed: 11/26/2022]
Abstract
The Thermotoga maritima arginine-binding protein (TmArgBP) has been modified to create a reagentless fluorescent protein biosensor. Two design methods for biosensor construction are compared: 1) solvent accessibility of environmentally-sensitive probes and 2) fluorescence deactivation due to photo-induced electron transfer (PET). Nine single cysteine TmArgBP mutants were created and labeled with three different environmentally sensitive fluorescent probes. These mutants demonstrated limited changes in fluorescence emission upon the addition of arginine. In contrast, the PET-based biosensor provides significant enhancements over the traditional approach and provides a fluorescence quenching mechanism that was capable of providing quantitative detection of arginine. Site-directed mutagenesis of TmArgBP was used to create attachment points for the fluorescent probe (K145C) and for an internal aromatic residue (D18X) to serve as the PET quencher. Both tyrosine and tryptophan, but not phenylalanine, were able to quench the emission of the fluorescent probe by more than 80% upon the addition of arginine. The dissociation constant for arginine ranged from 0.87 to 1.5 μM across the different sensors. This PET-based strategy provides a simple and broadly applicable approach for the analytical detection of small molecules that may be applied to any protein that exhibits conformational switching in a ligand dependent manner.
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Affiliation(s)
- Teraya Donaldson
- Department of Chemistry, University of Richmond, Richmond, VA, 23173, USA
| | - Luisa Iozzino
- Department of Chemistry, University of Richmond, Richmond, VA, 23173, USA; Laboratory for Molecular Sensing, ISA-CNR, Via Roma 64, 83100 Avellino, Italy
| | - Lindsay J Deacon
- Department of Chemistry, University of Richmond, Richmond, VA, 23173, USA
| | - Hilbert Billones
- Department of Chemistry, University of Richmond, Richmond, VA, 23173, USA
| | - Alessio Ausili
- Laboratory for Molecular Sensing, ISA-CNR, Via Roma 64, 83100 Avellino, Italy
| | - Sabato D'Auria
- Laboratory for Molecular Sensing, ISA-CNR, Via Roma 64, 83100 Avellino, Italy
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17
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Construction of Protein-Based Biosensors Using Ligand-Directed Chemistry for Detecting Analyte Binding. Methods Enzymol 2017; 589:253-280. [DOI: 10.1016/bs.mie.2017.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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18
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Discovery of allosteric modulators for GABAA receptors by ligand-directed chemistry. Nat Chem Biol 2016; 12:822-30. [DOI: 10.1038/nchembio.2150] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 05/17/2016] [Indexed: 12/26/2022]
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El-Sayed MMH, Brown SR, Mupparapu K, Tolosa L. The effect of pH on the glucose response of the glucose-galactose binding protein L255C labeled with Acrylodan. Int J Biol Macromol 2016; 86:282-7. [PMID: 26812111 DOI: 10.1016/j.ijbiomac.2016.01.077] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/18/2016] [Accepted: 01/21/2016] [Indexed: 11/16/2022]
Abstract
The glucose-galactose binding protein (GGBP) is used as an optical biosensor in medical and bioprocess applications. This paper investigates the effect of pH on the behavior of GGBP-L255C labeled with Acrylodan for the purpose of finding the optimum conditions for sensing purposes as well as for protein preparation, purification and storage. The Acrylodan-GGBP fluorescence response in absence and presence of glucose was measured under varying buffer and pH conditions. Dissociation constants (Kd) and Gibbs free energies (ΔG) for the protein-glucose binding were calculated. Binding was found to be energetically favored at slightly acidic to neutral conditions, specifically close to the pI of GBP (∼ 5.0). Minimal fluorescence response to glucose was exhibited at pH 3.0 accompanied by a blue shift in the steady state fluorescence spectrum. In contrast, an almost 45% response to glucose was shown at pH 4.5-9.0 with a 13-nm red shift. Frequency domain lifetime measurements and quenching with KI suggest that at highly acidic conditions both the glucose-free and the glucose-bound protein are in a conformation distinct from those observed at higher pH values.
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Affiliation(s)
- Mayyada M H El-Sayed
- Center for Advanced Sensor Technology, Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States.
| | - Sheniqua R Brown
- Center for Advanced Sensor Technology, Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States.
| | - KarunaSri Mupparapu
- Center for Advanced Sensor Technology, Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States.
| | - Leah Tolosa
- Center for Advanced Sensor Technology, Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States.
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Frost MC, Meyerhoff ME. Real-Time Monitoring of Critical Care Analytes in the Bloodstream with Chemical Sensors: Progress and Challenges. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2015; 8:171-92. [PMID: 26161973 DOI: 10.1146/annurev-anchem-071114-040443] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We review approaches and challenges in developing chemical sensor-based methods to accurately and continuously monitor levels of key analytes in blood related directly to the status of critically ill hospitalized patients. Electrochemical and optical sensor-based technologies have been pursued to measure important critical care species in blood [i.e., oxygen, carbon dioxide, pH, electrolytes (K(+), Na(+), Cl(-), etc.), glucose, and lactate] in real-time or near real-time. The two main configurations examined to date for achieving this goal have been intravascular catheter sensors and patient attached ex vivo sensors with intermittent blood sampling via an attached indwelling catheter. We discuss the status of these configurations and the main issues affecting the accuracy of the measurements, including cell adhesion and thrombus formation on the surface of the sensors, sensor drift, sensor selectivity, etc. Recent approaches to mitigate these nagging performance issues that have prevented these technologies from clinical use are also discussed.
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Affiliation(s)
- Megan C Frost
- Department of Biomedical Engineering, Michigan Technological University, Houghton, Michigan 49931-1295;
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Taguchi M, Ptitsyn A, McLamore ES, Claussen JC. Nanomaterial-mediated Biosensors for Monitoring Glucose. J Diabetes Sci Technol 2014; 8:403-411. [PMID: 24876594 PMCID: PMC4455391 DOI: 10.1177/1932296814522799] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Real-time monitoring of physiological glucose transport is crucial for gaining new understanding of diabetes. Many techniques and equipment currently exist for measuring glucose, but these techniques are limited by complexity of the measurement, requirement of bulky equipment, and low temporal/spatial resolution. The development of various types of biosensors (eg, electrochemical, optical sensors) for laboratory and/or clinical applications will provide new insights into the cause(s) and possible treatments of diabetes. State-of-the-art biosensors are improved by incorporating catalytic nanomaterials such as carbon nanotubes, graphene, electrospun nanofibers, and quantum dots. These nanomaterials greatly enhance biosensor performance, namely sensitivity, response time, and limit of detection. A wide range of new biosensors that incorporate nanomaterials such as lab-on-chip and nanosensor devices are currently being developed for in vivo and in vitro glucose sensing. These real-time monitoring tools represent a powerful diagnostic and monitoring tool for measuring glucose in diabetes research and point of care diagnostics. However, concerns over the possible toxicity of some nanomaterials limit the application of these devices for in vivo sensing. This review provides a general overview of the state of the art in nanomaterial-mediated biosensors for in vivo and in vitro glucose sensing, and discusses some of the challenges associated with nanomaterial toxicity.
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Affiliation(s)
- Masashige Taguchi
- Agricultural and Biological Engineering Department, University of Florida, Gainesville, FL, USA
| | - Andre Ptitsyn
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, USA
| | - Eric S McLamore
- Agricultural and Biological Engineering Department, University of Florida, Gainesville, FL, USA
| | - Jonathan C Claussen
- US Naval Research Laboratory, Center for Bio-Molecular Science and Engineering, Washington, DC, USA College of Science, George Mason University, Fairfax, VA, USA
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22
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Pickup JC, Khan F, Zhi ZL, Coulter J, Birch DJS. Fluorescence intensity- and lifetime-based glucose sensing using glucose/galactose-binding protein. J Diabetes Sci Technol 2013; 7:62-71. [PMID: 23439161 PMCID: PMC3692217 DOI: 10.1177/193229681300700108] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We review progress in our laboratories toward developing in vivo glucose sensors for diabetes that are based on fluorescence labeling of glucose/galactose-binding protein. Measurement strategies have included both monitoring glucose-induced changes in fluorescence resonance energy transfer and labeling with the environmentally sensitive fluorophore, badan. Measuring fluorescence lifetime rather than intensity has particular potential advantages for in vivo sensing. A prototype fiber-optic-based glucose sensor using this technology is being tested.
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Affiliation(s)
- John C Pickup
- Diabetes Research Group, King’s College London School of Medicine, Guy’s Hospital, London, United Kingdom.
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23
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Hsieh HV, Sherman DB, Andaluz SA, Amiss TJ, Pitner JB. Fluorescence resonance energy transfer glucose sensor from site-specific dual labeling of glucose/galactose binding protein using ligand protection. J Diabetes Sci Technol 2012; 6:1286-95. [PMID: 23294773 PMCID: PMC3570868 DOI: 10.1177/193229681200600607] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Site-selective modification of proteins at two separate locations using two different reagents is highly desirable for biosensor applications employing fluorescence resonance energy transfer (FRET), but few strategies are available for such modification. To address this challenge, sequential selective modification of two cysteines in glucose/galactose binding protein (GGBP) was demonstrated using a technique we call "ligand protection." METHOD In this technique, two cysteines were introduced in GGBP and one cysteine is rendered inaccessible by the presence of glucose, thus allowing sequential attachment of two different thiol-reactive reagents. The mutant E149C/A213C/L238S was first labeled at E149C in the presence of the ligand glucose. Following dialysis and removal of glucose, the protein was labeled with a second dye, either Texas Red (TR) C5 bromoacetamide or TR C2 maleimide, at the second site, A213C. RESULTS Changes in glucose-dependent fluorescence were observed that were consistent with FRET between the nitrobenzoxadiazole and TR fluorophores. Comparison of models and spectroscopic properties of the C2 and C5 TR FRET constructs suggests the greater rigidity of the C2 linker provides more efficient FRET. CONCLUSIONS The ligand protection strategy provides a simple method for labeling GGBP with two different fluorophores to construct FRET-based glucose sensors with glucose affinity within the human physiological glucose range (1-30 mM). This general strategy may also have broad utility for other protein-labeling applications.
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Affiliation(s)
- Helen V Hsieh
- BD Technologies, Research Triangle Park, NC 27709, USA.
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24
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Uchiyama S, Kimura K, Gota C, Okabe K, Kawamoto K, Inada N, Yoshihara T, Tobita S. Environment-Sensitive Fluorophores with Benzothiadiazole and Benzoselenadiazole Structures as Candidate Components of a Fluorescent Polymeric Thermometer. Chemistry 2012; 18:9552-63. [DOI: 10.1002/chem.201200597] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Indexed: 12/17/2022]
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Shao M, Xu X, Han J, Zhao J, Shi W, Kong X, Wei M, Evans DG, Duan X. Magnetic-field-assisted assembly of layered double hydroxide/metal porphyrin ultrathin films and their application for glucose sensors. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:8233-8240. [PMID: 21650214 DOI: 10.1021/la201521w] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The ordered ultrathin films (UTFs) based on CoFe-LDH (layered double hydroxide) nanoplatelets and manganese porphyrin (Mn-TPPS) have been fabricated on ITO substrates via a magnetic-field-assisted (MFA) layer-by-layer (LBL) method and were demonstrated as an electrochemical sensor for glucose. The XRD pattern for the film indicates a long-range stacking order in the normal direction of the substrate. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of the MFA LDH/Mn-TPPS UTFs reveal a continuous and uniform surface morphology. Cyclic voltammetry, impedance spectroscopy, and chronoamperometry were used to evaluate the electrochemical performance of the film, and the results show that the MFA-0.5 (0.5 T magnetic field) CoFe-LDH/Mn-TPPS-modified electrode displays the strongest redox current peaks and fastest electron transfer process compared with those of MFA-0 (without magnetic-field) and MFA-0.15 (0.15 T magnetic field). Furthermore, the MFA-0.5 CoFe-LDH/Mn-TPPS exhibits remarkable electrocatalytic activity toward the oxidation of glucose with a linear response range (0.1-15 mM; R(2) = 0.999), low detection limit (0.79 μM) and high sensitivity (66.3 μA mM(-1) cm(-2)). In addition, the glucose sensor prepared by the MFA LBL method also shows good selectivity and reproducibility as well as resistance to poisoning in a chloride ion solution. Therefore, the novel strategy in this work creates new opportunities for the fabrication of nonenzyme sensors with prospective applications in practical detection.
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Affiliation(s)
- Mingfei Shao
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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Sacks DB, Arnold M, Bakris GL, Bruns DE, Horvath AR, Kirkman MS, Lernmark A, Metzger BE, Nathan DM. Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus. Diabetes Care 2011; 34:e61-99. [PMID: 21617108 PMCID: PMC3114322 DOI: 10.2337/dc11-9998] [Citation(s) in RCA: 316] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Accepted: 02/28/2011] [Indexed: 02/06/2023]
Abstract
BACKGROUND Multiple laboratory tests are used to diagnose and manage patients with diabetes mellitus. The quality of the scientific evidence supporting the use of these tests varies substantially. APPROACH An expert committee compiled evidence-based recommendations for the use of laboratory testing for patients with diabetes. A new system was developed to grade the overall quality of the evidence and the strength of the recommendations. Draft guidelines were posted on the Internet and presented at the 2007 Arnold O. Beckman Conference. The document was modified in response to oral and written comments, and a revised draft was posted in 2010 and again modified in response to written comments. The National Academy of Clinical Biochemistry and the Evidence-Based Laboratory Medicine Committee of the American Association for Clinical Chemistry jointly reviewed the guidelines, which were accepted after revisions by the Professional Practice Committee and subsequently approved by the Executive Committee of the American Diabetes Association. CONTENT In addition to long-standing criteria based on measurement of plasma glucose, diabetes can be diagnosed by demonstrating increased blood hemoglobin A(1c) (HbA(1c)) concentrations. Monitoring of glycemic control is performed by self-monitoring of plasma or blood glucose with meters and by laboratory analysis of HbA(1c). The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of autoantibodies, urine albumin, insulin, proinsulin, C-peptide, and other analytes are addressed. SUMMARY The guidelines provide specific recommendations that are based on published data or derived from expert consensus. Several analytes have minimal clinical value at present, and their measurement is not recommended.
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Affiliation(s)
- David B Sacks
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland, USA.
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27
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Sacks DB, Arnold M, Bakris GL, Bruns DE, Horvath AR, Kirkman MS, Lernmark A, Metzger BE, Nathan DM. Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus. Clin Chem 2011; 57:e1-e47. [PMID: 21617152 DOI: 10.1373/clinchem.2010.161596] [Citation(s) in RCA: 300] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Multiple laboratory tests are used to diagnose and manage patients with diabetes mellitus. The quality of the scientific evidence supporting the use of these tests varies substantially. APPROACH An expert committee compiled evidence-based recommendations for the use of laboratory testing for patients with diabetes. A new system was developed to grade the overall quality of the evidence and the strength of the recommendations. Draft guidelines were posted on the Internet and presented at the 2007 Arnold O. Beckman Conference. The document was modified in response to oral and written comments, and a revised draft was posted in 2010 and again modified in response to written comments. The National Academy of Clinical Biochemistry and the Evidence Based Laboratory Medicine Committee of the AACC jointly reviewed the guidelines, which were accepted after revisions by the Professional Practice Committee and subsequently approved by the Executive Committee of the American Diabetes Association. CONTENT In addition to long-standing criteria based on measurement of plasma glucose, diabetes can be diagnosed by demonstrating increased blood hemoglobin A(1c) (Hb A(1c)) concentrations. Monitoring of glycemic control is performed by self-monitoring of plasma or blood glucose with meters and by laboratory analysis of Hb A(1c). The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of autoantibodies, urine albumin, insulin, proinsulin, C-peptide, and other analytes are addressed. SUMMARY The guidelines provide specific recommendations that are based on published data or derived from expert consensus. Several analytes have minimal clinical value at present, and their measurement is not recommended.
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Affiliation(s)
- David B Sacks
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, MD 20892-1508, USA.
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Yoon H, Ahn JH, Barone PW, Yum K, Sharma R, Boghossian AA, Han JH, Strano MS. Periplasmic Binding Proteins as Optical Modulators of Single-Walled Carbon Nanotube Fluorescence: Amplifying a Nanoscale Actuator. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201006167] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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29
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Yoon H, Ahn JH, Barone PW, Yum K, Sharma R, Boghossian AA, Han JH, Strano MS. Periplasmic Binding Proteins as Optical Modulators of Single-Walled Carbon Nanotube Fluorescence: Amplifying a Nanoscale Actuator. Angew Chem Int Ed Engl 2011; 50:1828-31. [DOI: 10.1002/anie.201006167] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 12/13/2010] [Indexed: 02/05/2023]
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Takaoka Y, Sun Y, Tsukiji S, Hamachi I. Mechanisms of chemical protein19F-labeling and NMR-based biosensor construction in vitro and in cells using self-assembling ligand-directed tosylate compounds. Chem Sci 2011. [DOI: 10.1039/c0sc00513d] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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31
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Saxl T, Khan F, Ferla M, Birch D, Pickup J. A fluorescence lifetime-based fibre-optic glucose sensor using glucose/galactose-binding protein. Analyst 2011; 136:968-72. [DOI: 10.1039/c0an00430h] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Khan F, Saxl TE, Pickup JC. Fluorescence intensity- and lifetime-based glucose sensing using an engineered high-Kd mutant of glucose/galactose-binding protein. Anal Biochem 2010; 399:39-43. [DOI: 10.1016/j.ab.2009.11.035] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 11/24/2009] [Accepted: 11/29/2009] [Indexed: 11/27/2022]
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Design strategies of fluorescent biosensors based on biological macromolecular receptors. SENSORS 2010; 10:1355-76. [PMID: 22205872 PMCID: PMC3244018 DOI: 10.3390/s100201355] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 01/29/2010] [Accepted: 02/04/2010] [Indexed: 11/17/2022]
Abstract
Fluorescent biosensors to detect the bona fide events of biologically important molecules in living cells are increasingly demanded in the field of molecular cell biology. Recent advances in the development of fluorescent biosensors have made an outstanding contribution to elucidating not only the roles of individual biomolecules, but also the dynamic intracellular relationships between these molecules. However, rational design strategies of fluorescent biosensors are not as mature as they look. An insatiable request for the establishment of a more universal and versatile strategy continues to provide an attractive alternative, so-called modular strategy, which permits facile preparation of biosensors with tailored characteristics by a simple combination of a receptor and a signal transducer. This review describes an overview of the progress in design strategies of fluorescent biosensors, such as auto-fluorescent protein-based biosensors, protein-based biosensors covalently modified with synthetic fluorophores, and signaling aptamers, and highlights the insight into how a given receptor is converted to a fluorescent biosensor. Furthermore, we will demonstrate a significance of the modular strategy for the sensor design.
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Loving GS, Sainlos M, Imperiali B. Monitoring protein interactions and dynamics with solvatochromic fluorophores. Trends Biotechnol 2010; 28:73-83. [PMID: 19962774 PMCID: PMC2818466 DOI: 10.1016/j.tibtech.2009.11.002] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 11/03/2009] [Accepted: 11/05/2009] [Indexed: 10/20/2022]
Abstract
Solvatochromic fluorophores possess emission properties that are sensitive to the nature of the local microenvironment. These dyes have been exploited in applications ranging from the study of protein structural dynamics to the detection of protein-binding interactions. Although the solvatochromic indole fluorophore of tryptophan has been utilized extensively for in vitro studies to advance our understanding of basic protein biochemistry, the emergence of new extrinsic synthetic dyes with improved properties, in conjunction with recent developments in site-selective methods to incorporate these chemical tools into proteins, now open the way for studies in more complex systems. Herein, we discuss recent technological advancements and their application in the design of powerful reporters, which serve critical roles in modern cell biology and assay development.
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Affiliation(s)
- Galen S Loving
- Department of Chemistry and Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA
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Wang H, Nakata E, Hamachi I. Recent progress in strategies for the creation of protein-based fluorescent biosensors. Chembiochem 2010; 10:2560-77. [PMID: 19693761 DOI: 10.1002/cbic.200900249] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The creation of novel bioanalytical tools for the detection and monitoring of a range of important target substances and biological events in vivo and in vitro is a great challenge in chemical biology and biotechnology. Protein-based fluorescent biosensors--integrated devices that convert a molecular-recognition event to a fluorescent signal--have recently emerged as a powerful tool. As the recognition units various proteins that can specifically recognize and bind a variety of molecules of biological significance with high affinity are employed. For the transducer, fluorescent proteins, such as green fluorescent protein (GFP) or synthetic fluorophores, are mostly adopted. Recent progress in protein engineering and organic synthesis allows us to manipulate proteins genetically and/or chemically, and a library of such protein scaffolds has been significantly expanded by genome projects. In this review, we briefly describe the recent progress of protein-based fluorescent biosensors on the basis of their platform and construction strategy, which are primarily divided into the genetically encoded fluorescent biosensors and chemically constructed biosensors.
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Affiliation(s)
- Hangxiang Wang
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
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Tsukiji S, Wang H, Miyagawa M, Tamura T, Takaoka Y, Hamachi I. Quenched ligand-directed tosylate reagents for one-step construction of turn-on fluorescent biosensors. J Am Chem Soc 2009; 131:9046-54. [PMID: 19499918 DOI: 10.1021/ja902486c] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Semisynthetic fluorescent biosensors consisting of a protein framework and a synthetic fluorophore are powerful analytical tools for specific detection of biologically relevant molecules. We report herein a novel method that allows for the construction of turn-on fluorescent semisynthetic biosensors in a one-step manner. The strategy is based on the ligand-directed tosyl (LDT) chemistry, a new type of affinity-guided protein labeling scheme which can site-specifically introduce synthetic probes to the surface of proteins with concomitant release of the affinity ligands. Novel quenched ligand-directed tosylate (Q-LDT) reagents were designed by connecting an organic dye to a conjugate of a protein ligand and a fluorescence quencher through a tosyl linker. The Q-LDT-mediated labeling directly converts a natural protein to a fluorescently labeled protein that remains noncovalently complexed with the cleaved ligand-tethered quencher. The fluorescence of this labeled protein is initially quenched and only in the presence of specific analytes is the fluorescence enhanced (turned on) due to the expulsion of the ligand-quencher fragment. Using a single labeling step, this approach was successfully applied to carbonic anhydrase II (CAII) and a Src homology 2 (SH2) domain to generate turn-on fluorescent biosensors toward CAII inhibitors and phosphotyrosine peptides, respectively. Detailed investigations revealed that the obtained biosensors exhibit their natural ligand selectivity. The high target-specificity of the LDT chemistry also allowed us to prepare the SH2 domain-based biosensor not only in a purified form but also in a bacterial cell lysate. These results demonstrate the utility of the Q-LDT-based approach to expand the applications of semisynthetic biosensors.
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Affiliation(s)
- Shinya Tsukiji
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
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Saxl T, Khan F, Matthews DR, Zhi ZL, Rolinski O, Ameer-Beg S, Pickup J. Fluorescence lifetime spectroscopy and imaging of nano-engineered glucose sensor microcapsules based on glucose/galactose-binding protein. Biosens Bioelectron 2009; 24:3229-34. [PMID: 19442507 DOI: 10.1016/j.bios.2009.04.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Revised: 03/26/2009] [Accepted: 04/06/2009] [Indexed: 01/14/2023]
Abstract
We aimed to develop microsensors for eventual glucose monitoring in diabetes, based on fluorescence lifetime changes in glucose/galactose-binding protein (GBP) labelled with the environmentally sensitive fluorophore dye, badan. A mutant of GBP was labelled with badan near the binding site, the protein adsorbed to microparticles of CaCO(3) as templates and encapsulated in alternating nano-layers of poly-L-lysine and heparin. We used fluorescence lifetime imaging (FLIM) with two-photon excitation and time-correlated single-photon counting to visualize the lifetime changes in the capsules. Addition of glucose increased the mean lifetime of GBP-badan by a maximum of approximately 2 ns. Analysis of fluorescence decay curves was consistent with two GBP states, a short-lifetime component (approximately 0.8 ns), likely representing the open form of the protein with no bound glucose, and a long-lifetime component (approximately 3.1 ns) representing the closed form with bound glucose and where the lobes of GBP have closed round the dye creating a more hydrophobic environment. FLIM demonstrated that increasing glucose increased the fractional proportion of the long-lifetime component. We conclude that fluorescence lifetime-based glucose sensing using GBP encapsulated with nano-engineered layer-by-layer films is a glucose monitoring technology suitable for development in diabetes management.
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Affiliation(s)
- Tania Saxl
- Metabolic Unit, King's College London School of Medicine, Guy's Hospital, London, UK.
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Tolosa L. On the design of low-cost fluorescent protein biosensors. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2009; 116:143-57. [PMID: 19347267 DOI: 10.1007/10_2008_39] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
Abstract
There is a large body of knowledge on proteins and their ligands that is available to the sensor researcher for the successful design of fluorescent biosensors. Chemically synthesized receptors rarely match the sensitivity and selectivity of proteins.Additionally, proteins are easily produced and manipulated through recombinant protein techniques. Although limitations exist in the prediction of signal response of proteins labeled with fluorescent probes, thoughtful experimentation can lead to useful, highly responsive fluorescent protein assays. Conversion of these assays into sensor devices may require additional manipulation of the fluorescence properties of the labeled proteins. We have shown that this can be achieved by a second fluorophore serving as a reference for ratiometric measurements. The choice of reference is contingent on the low-cost, miniaturized design of the device. Accordingly, the reference fluorophore is excitable with the same LED as the signal transducing probe and has a fluorescence decay lifetime that is orders of magnitude longer.Alternating illumination with intensity modulated light at two frequencies allows for ratiometric sensing without the need for bulky filter wheels while collecting the signals over a wide range of emission wavelengths. The result is a simple optoelectronics design that is cost-effective and small enough to be portable.In summary, the process of designing protein-based fluorescent biosensors for practical applications requires the systematic collaboration of a cross-disciplinary group of molecular biologists, chemists and engineers.
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Affiliation(s)
- Leah Tolosa
- Center for Advanced Sensor Technology, University of Maryland Baltimore County, Baltimore, MD21050, USA
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Abstract
Nanomedicine involves measurement and therapy at the level of 1-100 nm. Although the science is still in its infancy, it has major potential applications in diabetes. These include solving needs such as non-invasive glucose monitoring using implanted nanosensors, with key techniques being fluorescence resonance energy transfer (FRET) and fluorescence lifetime sensing, as well as new nano-encapsulation technologies for sensors such as layer-by-layer (LBL) films. The latter might also achieve better insulin delivery in diabetes by both improved islet encapsulation and oral insulin formulations. An 'artificial nanopancreas' could be an alternative closed-loop insulin delivery system. Other applications of nanomedicine include targeted molecular imaging in vivo (e.g. tissue complications) using quantum dots (QDs) or gold nanoparticles, and single-molecule detection for the study of molecular diversity in diabetes pathology.
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Abstract
Autoinducer 2 (AI-2), which enables different bacterial species to engage in interspecies communication, has been difficult to detect quantitatively. Currently, the most commonly used method for AI-2 detection employs an engineered Vibrio harveyi reporter strain, which produces bioluminescence in response to AI-2. However, the bioassay is not quantitative and is sensitive to assay conditions. In this work, we have developed two protein sensors for AI-2 by modifying AI-2 receptor proteins LuxP and LsrB with environmentally sensitive fluorescent dyes. The protein sensors bind specifically to AI-2 and produce dose-dependent changes in their fluorescence yield. The new assay method has been applied to monitor the enzymatic synthesis of AI-2 in real time and determine the extracellular and intracellular AI-2 concentrations in several bacterial culture fluids.
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Affiliation(s)
- Jinge Zhu
- Department of Chemistry and Ohio State Biochemistry Program, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210
| | - Dehua Pei
- Department of Chemistry and Ohio State Biochemistry Program, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210
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Azzaroni O, Yameen B, Knoll W. Effect of the electrostatic microenvironment on the observed redox potential of electroactive supramolecular bioconjugates. Phys Chem Chem Phys 2008; 10:7031-8. [DOI: 10.1039/b806445h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lambrianou A, Demin S, Hall EAH. Protein engineering and electrochemical biosensors. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2008; 109:65-96. [PMID: 17960341 DOI: 10.1007/10_2007_080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Protein engineered biosensors provide the next best step in the advancement of protein-based sensors that can specifically identify chemical substrates. The use of native proteins for this purpose cannot adequately embrace the limits of detection and level of stability required for a usable sensor, due to globular structure restraints. This review chapter attempts to give an accurate representation of the three main strategies employed in the engineering of more suitable biological components for use in biosensor construction. The three main strategies in protein engineering for electrochemical biosensor implementation are: rational protein design, directed evolution and de novo protein design. Each design strategy has limitations to its use in a biosensor format and has advantages and disadvantages with respect to each. The three design techniques are used to modify aspects of stability, sensitivity, selectivity, surface tethering, and signal transduction within the biological environment. Furthermore with the advent of new nanomaterials the implementation of these design strategies, with the attomolar promise of nanostructures, imparts important generational leaps in research for biosensor construction, based on highly specific, very robust, and electrically wired protein engineered biosensors.
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Affiliation(s)
- Andreas Lambrianou
- Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge, UK
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Khan F, Gnudi L, Pickup JC. Fluorescence-based sensing of glucose using engineered glucose/galactose-binding protein: A comparison of fluorescence resonance energy transfer and environmentally sensitive dye labelling strategies. Biochem Biophys Res Commun 2008; 365:102-6. [DOI: 10.1016/j.bbrc.2007.10.129] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 10/24/2007] [Indexed: 10/22/2022]
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Ge X, Lam H, Modi SJ, LaCourse WR, Rao G, Tolosa L. Comparing the performance of the optical glucose assay based on glucose binding protein with high-performance anion-exchange chromatography with pulsed electrochemical detection: efforts to design a low-cost point-of-care glucose sensor. J Diabetes Sci Technol 2007; 1:864-72. [PMID: 19885158 PMCID: PMC2769676 DOI: 10.1177/193229680700100610] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The glucose binding protein (GBP) is one of many soluble binding proteins found in the periplasmic space of gram-negative bacteria. These proteins are responsible for chemotactic responses and active transport of chemical species across the membrane. Upon ligand binding, binding proteins undergo a large conformational change, which is the basis for converting these proteins into optical biosensors. METHODS The GBP biosensor was prepared by attaching a polarity-sensitive fluorescent probe to a single cysteine mutation at a site on the protein that is allosterically responsive to glucose binding. The fluorescence response of the resulting sensor was validated against high-performance anion-exchange chromatography (HPAEC) with pulsed electrochemical detection. Finally, a simple fluorescence reader was built using a lifetime-assisted ratiometric technique. RESULTS The GBP assay has a linear range of quantification of 0.100-2.00 microM and a sensitivity of 0.164 microM(-1) under the specified experimental conditions. The comparison between GBP and HPAEC readings for nine blind samples indicates that there is no statistical difference between the analytical results of the two methods at the 95% confidence level. Although the methods of fluorescence detection are based on different principles, the response of the homemade device to glucose concentrations was comparable to the response of the larger and more expensive tabletop fluorescence spectrophotometer. CONCLUSIONS A glucose binding protein labeled with a polarity-sensitive probe can be used for measuring micromolar amounts of glucose. Using a lifetime-assisted ratiometric technique, a low-cost GBP-based micromolar glucose monitor could be built.
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Affiliation(s)
- Xudong Ge
- Center for Advanced Sensor Technology, Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, Baltimore, Maryland
| | - Hung Lam
- Center for Advanced Sensor Technology, Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, Baltimore, Maryland
| | - Swati J. Modi
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland
| | - William R. LaCourse
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland
| | - Govind Rao
- Center for Advanced Sensor Technology, Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, Baltimore, Maryland
| | - Leah Tolosa
- Center for Advanced Sensor Technology, Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, Baltimore, Maryland
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Mansoorabadi SO, Thibodeaux CJ, Liu HW. The diverse roles of flavin coenzymes--nature's most versatile thespians. J Org Chem 2007; 72:6329-42. [PMID: 17580897 PMCID: PMC2519020 DOI: 10.1021/jo0703092] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Flavin coenzymes play a variety of roles in biological systems. This Perspective highlights the chemical versatility of flavins by reviewing research on five flavoenzymes that have been studied in our laboratory. Each of the enzymes discussed in this review [the acyl-CoA dehydrogenases (ACDs), CDP-6-deoxy-l-threo-d-glycero-4-hexulose-3-dehydrase reductase (E3), CDP-4-aceto-3,6-dideoxygalactose synthase (YerE), UDP-galactopyranose mutase (UGM), and type II isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-2)] utilizes flavin in a distinct role. In particular, the catalytic mechanisms of two of these enzymes, UGM and IDI-2, may involve novel flavin chemistry.
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Affiliation(s)
- Steven O. Mansoorabadi
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA
| | - Christopher J. Thibodeaux
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA
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Abstract
Glucose/galactose binding protein (GGBP) functions in two different larger systems of proteins used by enteric bacteria for molecular recognition and signaling. Here we report on the thermodynamics of conformational equilibrium distributions of GGBP. Three fluorescence components appear at zero glucose concentration and systematically transition to three components at high glucose concentration. Fluorescence anisotropy correlations, fluorescent lifetimes, thermodynamics, computational structure minimization, and literature work were used to assign the three components as open, closed, and twisted conformations of the protein. The existence of three states at all glucose concentrations indicates that the protein continuously fluctuates about its conformational state space via thermally driven state transitions; glucose biases the populations by reorganizing the free energy profile. These results and their implications are discussed in terms of the two types of specific and nonspecific interactions GGBP has with cytoplasmic membrane proteins.
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Affiliation(s)
- Troy C Messina
- Department of Chemistry and Chemical Biology, The State University of New Jersey, Piscataway, New Jersey 08854, USA
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