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Pieri E, Walker AR, Zhu M, Martínez TJ. Conical Intersection Accessibility Dictates Brightness in Red Fluorescent Proteins. J Am Chem Soc 2024; 146:17646-17658. [PMID: 38885641 DOI: 10.1021/jacs.4c00458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Red fluorescent protein (RFP) variants are highly sought after for in vivo imaging since longer wavelengths improve depth and contrast in fluorescence imaging. However, the lower energy emission wavelength usually correlates with a lower fluorescent quantum yield compared to their green emitting counterparts. To guide the rational design of bright variants, we have theoretically assessed two variants (mScarlet and mRouge) which are reported to have very different brightness. Using an α-CASSCF QM/MM framework (chromophore and all protein residues within 6 Å of it in the QM region, for a total of more than 450 QM atoms), we identify key points on the ground and first excited state potential energy surfaces. The brighter variant mScarlet has a rigid scaffold, and the chromophore stays largely planar on the ground state. The dimmer variant mRouge shows more flexibility and can accommodate a pretwisted chromophore conformation which provides easier access to conical intersections. The main difference between the variants lies in the intersection seam regions, which appear largely inaccessible in mScarlet but partially accessible in mRouge. This observation is mainly related with changes in the cavity charge distribution, the hydrogen-bonding network involving the chromophore and a key ARG/THR mutation (which changes both charge and steric hindrance).
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Affiliation(s)
- Elisa Pieri
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Alice R Walker
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Mingning Zhu
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Todd J Martínez
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
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Hou Y, Zhang W, McGilvray PT, Sobczyk M, Wang T, Weng SHS, Huff A, Huang S, Pena N, Katanski CD, Pan T. Engineered mischarged transfer RNAs for correcting pathogenic missense mutations. Mol Ther 2024; 32:352-371. [PMID: 38104240 PMCID: PMC10861979 DOI: 10.1016/j.ymthe.2023.12.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 11/08/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023] Open
Abstract
Missense mutations account for approximately 50% of pathogenic mutations in human genetic diseases, and most lack effective treatments. Gene therapies, gene editing, and RNA therapies, including transfer RNA (tRNA) modalities, are common strategies for genetic disease treatments. However, reported tRNA therapies are for nonsense mutations only. It has not been explored how tRNAs can be engineered to correct missense mutations. Here, we describe missense-correcting tRNAs (mc-tRNAs) as a potential therapeutic for correcting pathogenic missense mutations. Mc-tRNAs are engineered tRNAs charged with one amino acid, but read codons of another in translation. We first developed a series of fluorescent protein-based reporters that indicate the successful correction of missense mutations via restoration of fluorescence. We engineered mc-tRNAs that effectively corrected serine and arginine missense mutations in the reporters and confirmed the amino acid substitution by mass spectrometry and mc-tRNA expression by sequencing. We examined the transcriptome response to mc-tRNA expression and found some mc-tRNAs induced minimum transcriptomic changes. Furthermore, we applied an mc-tRNA to rescue a pathogenic CAPN3 Arg-to-Gln mutant involved in LGMD2A. These results establish a versatile pipeline for mc-tRNA engineering and demonstrate the potential of mc-tRNA as an alternative therapeutic platform for the treatment of genetic disorders.
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Affiliation(s)
- Yichen Hou
- Committee on Genomics, Genetics and Systems Biology, University of Chicago, Chicago, IL 60637, USA
| | - Wen Zhang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | | | - Marek Sobczyk
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Tianxin Wang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | | | - Allen Huff
- Proteomics Platform, University of Chicago, Chicago, IL 60637, USA
| | - Sihao Huang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Noah Pena
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | | | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA.
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Sinha D, Sinha D, Banerjee N, Rai P, Seal S, Chakraborty T, Chatterjee S, Sau S. A conserved arginine residue in a staphylococcal anti-sigma factor is required to preserve its kinase activity, structure, and stability. J Biomol Struct Dyn 2020; 40:4972-4986. [PMID: 33356973 DOI: 10.1080/07391102.2020.1864475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
RsbW, σB, and RsbV, encoded by Staphylococcus aureus and related bacteria, act as an anti-sigma factor, an sigma factor, and an anti-anti-sigma factor, respectively. The interaction between RsbW and σB blocks the transcription initiation activity of the latter protein. RsbW also functions as a serine kinase and phosphorylates RsbV in the presence of ATP. Our modeling study indicates that the RsbW-RsbV complex is stabilized by twenty-four intermolecular non-covalent bonds. Of the bond-forming RsbW residues, Arg 23, and Glu 49 are conserved residues. To understand the roles of Arg 23 in RsbW, rRsbW[R23A], a recombinant S. aureus RsbW (rRsbW) harboring Arg to Ala change at position 23, was investigated using various probes. The results reveal that rRsbW[R23A], like rRsbW, exists as the dimers in the aqueous solution. However, rRsbW[R23A], unlike rRsbW, neither interacted with a chimeric RsbV (rRsbV) nor formed the phosphorylated rRsbV in the presence of ATP. Furthermore, the tertiary structure and hydrophobic surface area of rRsbW[R23A] matched little with those of rRsbW. Conversely, both rRsbW[R23A] and rRsbW showed interaction with a recombinant σB (rσB). rRsbW and rRsbW[R23A] were also unfolded via the formation of at least one intermediate in the presence of urea. However, the thermodynamic stability of rRsbW significantly differed from that of rRsbW[R23A]. Our molecular dynamics (MD) simulation study also reveals the substantial change of structure, dimension, and stability of RsbW due to the above mutation. The ways side chain of critical Arg 23 contributes to maintaining the tertiary structure, and stability of RsbW was elaborately discussed.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Debasmita Sinha
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
| | - Debabrata Sinha
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
| | - Nilanjan Banerjee
- Department of Biophysics, Bose Institute, Kolkata, West Bengal, India
| | - Priya Rai
- Department of Biophysics, Bose Institute, Kolkata, West Bengal, India
| | - Soham Seal
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
| | | | | | - Subrata Sau
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
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4
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Chen F, Zhao X, Liang W. One- and two-photon absorption spectra of the yellow fluorescent protein citrine: effects of intramolecular electron-vibrational coupling and intermolecular interactions. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1426130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Fasheng Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen, China
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Xinyi Zhao
- Department of Science and Technology for Inspection, Xiamen Huaxia University, Xiamen, China
| | - WanZhen Liang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen, China
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
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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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Stepanenko OV, Stepanenko OV, Kuznetsova IM, Uversky VN, Turoverov KK. Peculiarities of the Super-Folder GFP Folding in a Crowded Milieu. Int J Mol Sci 2016; 17:ijms17111805. [PMID: 27801849 PMCID: PMC5133806 DOI: 10.3390/ijms17111805] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/11/2016] [Accepted: 10/20/2016] [Indexed: 01/19/2023] Open
Abstract
The natural cellular milieu is crowded by large quantities of various biological macromolecules. This complex environment is characterized by a limited amount of unoccupied space, limited amounts of free water, and changed solvent properties. Obviously, such a tightly packed cellular environment is poorly mimicked by traditional physiological conditions, where low concentrations of a protein of interest are analyzed in slightly salted aqueous solutions. An alternative is given by the use of a model crowded milieu, where a protein of interest is immersed in a solution containing high concentrations of various polymers that serve as model crowding agents. An expected outcome of the presence of such macromolecular crowding agents is their ability to increase conformational stability of a globular protein due to the excluded volume effects. In line with this hypothesis, the behavior of a query protein should be affected by the hydrodynamic size and concentration of an inert crowder (i.e., an agent that does not interact with the protein), whereas the chemical nature of a macromolecular crowder should not play a role in its ability to modulate conformational properties. In this study, the effects of different crowding agents (polyethylene glycols (PEGs) of various molecular masses (PEG-600, PEG-8000, and PEG-12000), Dextran-70, and Ficoll-70) on the spectral properties and unfolding–refolding processes of the super-folder green fluorescent protein (sfGFP) were investigated. sfGFP is differently affected by different crowders, suggesting that, in addition to the expected excluded volume effects, there are some changes in the solvent properties.
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Affiliation(s)
- Olesya V Stepanenko
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
| | - Olga V Stepanenko
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
| | - Irina M Kuznetsova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
| | - Vladimir N Uversky
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd. MDC07, Tampa, FL 33612, USA.
| | - Konstantin K Turoverov
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
- Institute of Physics, Nanotechnology and Telecommunications, Peter the Great St. Petersburg State Polytechnic University, 29 Polytechnicheskaya st., St. Petersburg 195251, Russia.
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7
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Abstract
Superfolder variant of the green fluorescent protein (sfGFP) became a favorite probe for examination of the unfolding–refolding processes of fluorescent proteins with beta-barrel structure owing to its reversible unfolding in comparison with other fluorescent proteins. Its benefit is the proper folding even in fusion constructions with poorly folded polypeptides. We noticed that guanidine thiocyanate affects not only the structure of protein but its chromophore directly. Therefore we studied the influence of ionic denaturants and salts including guanidine thiocyanate, guanidine hydrochloride, sodium chloride and sodium thiocyanate on spectral features of sfGFP. It was shown that moderate amounts of the studied agents do not disrupt sfGFP structure but provoke pronounced alteration of its spectral characteristics. Changes in absorption and CD spectra in visible spectral range indicate the specific binding of SCN− and Cl− anions in the sfGFP chromophore vicinity. The anion binding results in the redistribution of sfGFP molecules with neutral and anionic chromophores. This also hinders the proton transfer in the chromophore excited state, considerably decreasing the fluorescence intensity of sfGFP. Our results indicate that when ionic denaturants are used in the studies of fluorescent protein folding their effect on fluorophore charge state should be taken into account.
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Bochenkova AV, Klaerke B, Rahbek DB, Rajput J, Toker Y, Andersen LH. UV Excited-State Photoresponse of Biochromophore Negative Ions. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Bochenkova AV, Klaerke B, Rahbek DB, Rajput J, Toker Y, Andersen LH. UV Excited-State Photoresponse of Biochromophore Negative Ions. Angew Chem Int Ed Engl 2014; 53:9797-801. [DOI: 10.1002/anie.201404609] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Indexed: 11/09/2022]
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10
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Dedecker P, De Schryver FC, Hofkens J. Fluorescent Proteins: Shine on, You Crazy Diamond. J Am Chem Soc 2013; 135:2387-402. [DOI: 10.1021/ja309768d] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Peter Dedecker
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Frans C. De Schryver
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Johan Hofkens
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
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Distinct effects of guanidine thiocyanate on the structure of superfolder GFP. PLoS One 2012; 7:e48809. [PMID: 23144981 PMCID: PMC3492234 DOI: 10.1371/journal.pone.0048809] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 10/05/2012] [Indexed: 11/22/2022] Open
Abstract
Having a high folding efficiency and a low tendency to aggregate, the superfolder GFP (sfGFP) offers a unique opportunity to study the folding of proteins that have a β-barrel topology. Here, we studied the unfolding–refolding of sfGFP that was induced by guanidine thiocyanate (GTC), which is a stronger denaturing agent than GdnHCl or urea. Structural perturbations of sfGFP were studied by spectroscopic methods (absorbance, fluorescence, and circular dichroism), by acrylamide quenching of tryptophan and green chromophore fluorescence, and by size-exclusion chromatography. Low concentrations of GTC (up to 0.1 M) induce subtle changes in the sfGFP structure. The pronounced changes in the visible absorption spectrum of sfGFP which are accompanied by a dramatic decrease in tryptophan and green chromophore fluorescence was recorded in the range 0–0.7 M GNC. These alterations of sfGFP characteristics that erroneously can be mixed up with appearance of intermediate state in fact have pure spectroscopic but not structural nature. Higher concentrations of GTC (from 0.7 to 1.7 M), induce a disruption of the sfGFP structure, that is manifested in simultaneous changes of all of the detected parameters. Full recovery of native properties of denaturated sfGFP was observed after denaturant removal. The refolding of sfGFP passes through the accumulation of the off-pathway intermediate state, in which inner alpha-helix and hence green chromophore and Trp57 are still not tuned up to (properly integrated into) the already formed β-barrel scaffold of protein. Incorporation of the chromophore in the β-barrel in the pathway of refolding and restoration of its ability to fluoresce occur in a narrow range of GTC concentrations from 1.0 to 0.7 M, and a correct insertion of Trp 57 occurs at concentrations ranging from 0.7 to 0 M GTC. These two processes determine the hysteresis of protein unfolding and refolding.
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12
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Filonov GS, Piatkevich KD, Ting LM, Zhang J, Kim K, Verkhusha VV. Bright and stable near-infrared fluorescent protein for in vivo imaging. Nat Biotechnol 2011; 29:757-61. [PMID: 21765402 PMCID: PMC3152693 DOI: 10.1038/nbt.1918] [Citation(s) in RCA: 517] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 06/15/2011] [Indexed: 11/22/2022]
Abstract
The ability of non-invasive monitoring of deep-tissue developmental, metabolic, and pathogenic processes will advance modern biotechnology. Imaging of live mammals using fluorescent probes is more feasible within a “near-infrared optical window” (NIRW)1. Here we report a phytochrome-based near infra-red fluorescent protein (iRFP) with the excitation/emission maxima at 690/713 nm. Bright fluorescence in a living mouse proved iRFP to be a superior probe for non-invasive imaging of internal mammalian tissues. Its high intracellular stability, low cytotoxicity, and lack of the requirement to add external biliverdin-chromophore makes iRFP as easy to use as conventional GFP-like proteins. Compared to earlier phytochrome-derived fluorescent probes, the iRFP protein has better in vitro characteristics and performs well in cells and in vivo, having greater effective brightness and photostability. Compared to the far-red GFP-like proteins, iRFP has substantially higher signal to background ratio in a mouse model owing to its infra-red shifted spectra.
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Affiliation(s)
- Grigory S Filonov
- Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York, USA
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13
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Craggs TD. Green fluorescent protein: structure, folding and chromophore maturation. Chem Soc Rev 2009; 38:2865-75. [PMID: 19771333 DOI: 10.1039/b903641p] [Citation(s) in RCA: 173] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The prolific use of green fluorescent protein and its variants throughout cellular biology relies on the post-translational formation of the chromophore, which proceeds without the need for any additional enzymes or cofactors, except molecular oxygen. In order to form the mature chromophore, the polypeptide backbone must undergo four distinct processes: folding, cyclisation, oxidation and dehydration. This tutorial review looks in detail at the proposed mechanisms for chromophore formation arising out of experimental and computational studies. The folding process is discussed, and the role that the native state plays in catalysing the initial cyclisation and subsequent chemistry is analysed. The specific functions of four conserved residues (Y66, G67, R96 and E222) in the maturation process are also presented. A greater understanding of the maturation process of fluorescent proteins from both jellyfish and coral species will profit the ongoing quest for brighter, faster maturing, genetically-encodable fluorescent probes of all colours, thus increasing their utility throughout the biomedical sciences.
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Affiliation(s)
- Timothy D Craggs
- School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, UK KY16 9SS.
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