1
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Feng RR, Wang M, Zhang W, Gai F. Unnatural Amino Acids for Biological Spectroscopy and Microscopy. Chem Rev 2024; 124:6501-6542. [PMID: 38722769 DOI: 10.1021/acs.chemrev.3c00944] [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: 05/23/2024]
Abstract
Due to advances in methods for site-specific incorporation of unnatural amino acids (UAAs) into proteins, a large number of UAAs with tailored chemical and/or physical properties have been developed and used in a wide array of biological applications. In particular, UAAs with specific spectroscopic characteristics can be used as external reporters to produce additional signals, hence increasing the information content obtainable in protein spectroscopic and/or imaging measurements. In this Review, we summarize the progress in the past two decades in the development of such UAAs and their applications in biological spectroscopy and microscopy, with a focus on UAAs that can be used as site-specific vibrational, fluorescence, electron paramagnetic resonance (EPR), or nuclear magnetic resonance (NMR) probes. Wherever applicable, we also discuss future directions.
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Affiliation(s)
- Ran-Ran Feng
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Manxi Wang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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2
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Fujinami D, Garcia de Gonzalo CV, Biswas S, Hao Y, Wang H, Garg N, Lukk T, Nair SK, van der Donk WA. Structural and mechanistic investigations of protein S-glycosyltransferases. Cell Chem Biol 2021; 28:1740-1749.e6. [PMID: 34283964 DOI: 10.1016/j.chembiol.2021.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/06/2021] [Accepted: 06/28/2021] [Indexed: 10/20/2022]
Abstract
Attachment of sugars to nitrogen and oxygen in peptides is ubiquitous in biology, but glycosylation of sulfur atoms has only been recently described. Here, we characterize two S-glycosyltransferases SunS and ThuS that selectively glycosylate one of five Cys residues in their substrate peptides; substitution of this Cys with Ser results in a strong decrease in glycosylation activity. Crystal structures of SunS and ThuS in complex with UDP-glucose or a derivative reveal an unusual architecture in which a glycosyltransferase type A (GTA) fold is decorated with additional domains to support homodimerization. Dimer formation creates an extended cavity for the substrate peptide, drawing functional analogy with O-glycosyltransferases involved in cell wall biosynthesis. This extended cavity contains a sharp bend that may explain the site selectivity of the glycosylation because the target Cys is in a Gly-rich stretch that can accommodate the bend. These studies establish a molecular framework for understanding the unusual S-glycosyltransferases.
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Affiliation(s)
- Daisuke Fujinami
- Howard Hughes Medical Institute and Roger Adams Laboratory, Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - Chantal V Garcia de Gonzalo
- Howard Hughes Medical Institute and Roger Adams Laboratory, Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - Subhanip Biswas
- Howard Hughes Medical Institute and Roger Adams Laboratory, Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - Yue Hao
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - Huan Wang
- Howard Hughes Medical Institute and Roger Adams Laboratory, Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - Neha Garg
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - Tiit Lukk
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - Satish K Nair
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA.
| | - Wilfred A van der Donk
- Howard Hughes Medical Institute and Roger Adams Laboratory, Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA; Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA.
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3
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Ahmed IA, Acharyya A, Eng CM, Rodgers JM, DeGrado WF, Jo H, Gai F. 4-Cyanoindole-2'-deoxyribonucleoside as a Dual Fluorescence and Infrared Probe of DNA Structure and Dynamics. Molecules 2019; 24:E602. [PMID: 30744004 PMCID: PMC6384856 DOI: 10.3390/molecules24030602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/26/2019] [Accepted: 02/05/2019] [Indexed: 11/16/2022] Open
Abstract
Unnatural nucleosides possessing unique spectroscopic properties that mimic natural nucleobases in both size and chemical structure are ideally suited for spectroscopic measurements of DNA/RNA structure and dynamics in a site-specific manner. However, such unnatural nucleosides are scarce, which prompts us to explore the utility of a recently found unnatural nucleoside, 4-cyanoindole-2'-deoxyribonucleoside (4CNI-NS), as a site-specific spectroscopic probe of DNA. A recent study revealed that 4CNI-NS is a universal nucleobase that maintains the high fluorescence quantum yield of 4-cyanoindole and that among the four natural nucleobases, only guanine can significantly quench its fluorescence. Herein, we further show that the C≡N stretching frequency of 4CNI-NS is sensitive to the local environment, making it a useful site-specific infrared probe of oligonucleotides. In addition, we demonstrate that the fluorescence-quencher pair formed by 4CNI-NS and guanine can be used to quantitatively assess the binding affinity of a single-stranded DNA to the protein system of interest via fluorescence spectroscopy, among other applications. We believe that this fluorescence binding assay is especially useful as its potentiality allows high-throughput screening of DNA⁻protein interactions.
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Affiliation(s)
- Ismail A Ahmed
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Arusha Acharyya
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Christina M Eng
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Jeffrey M Rodgers
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA.
| | - Hyunil Jo
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA.
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
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4
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Vibrational Approach to the Dynamics and Structure of Protein Amyloids. Molecules 2019; 24:molecules24010186. [PMID: 30621325 PMCID: PMC6337179 DOI: 10.3390/molecules24010186] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 12/31/2018] [Accepted: 01/02/2019] [Indexed: 02/06/2023] Open
Abstract
Amyloid diseases, including neurodegenerative diseases such as Alzheimer’s and Parkinson’s, are linked to a poorly understood progression of protein misfolding and aggregation events that culminate in tissue-selective deposition and human pathology. Elucidation of the mechanistic details of protein aggregation and the structural features of the aggregates is critical for a comprehensive understanding of the mechanisms of protein oligomerization and fibrillization. Vibrational spectroscopies, such as Fourier transform infrared (FTIR) and Raman, are powerful tools that are sensitive to the secondary structure of proteins and have been widely used to investigate protein misfolding and aggregation. We address the application of the vibrational approaches in recent studies of conformational dynamics and structural characteristics of protein oligomers and amyloid fibrils. In particular, introduction of isotope labelled carbonyl into a peptide backbone, and incorporation of the extrinsic unnatural amino acids with vibrational moieties on the side chain, have greatly expanded the ability of vibrational spectroscopy to obtain site-specific structural and dynamic information. The applications of these methods in recent studies of protein aggregation are also reviewed.
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5
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Liu H, Morris C, Lantz R, Kent TW, Elbassal EA, Wojcikiewicz EP, Du D. Residue‐Specific Dynamics and Local Environmental Changes in Aβ40 Oligomer and Fibril Formation. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201802490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Haiyang Liu
- Department of Chemistry and BiochemistryFlorida Atlantic University 777 Glades Road Boca Raton FL 33431 USA
| | - Clifford Morris
- Department of Chemistry and BiochemistryFlorida Atlantic University 777 Glades Road Boca Raton FL 33431 USA
| | - Richard Lantz
- Department of Chemistry and BiochemistryFlorida Atlantic University 777 Glades Road Boca Raton FL 33431 USA
| | - Thomas W. Kent
- Department of Chemistry and BiochemistryFlorida Atlantic University 777 Glades Road Boca Raton FL 33431 USA
| | - Esmail A. Elbassal
- Department of Chemistry and BiochemistryFlorida Atlantic University 777 Glades Road Boca Raton FL 33431 USA
| | - Ewa P. Wojcikiewicz
- Department of Biomedical ScienceFlorida Atlantic University 777 Glades Road Boca Raton FL 33431 USA
| | - Deguo Du
- Department of Chemistry and BiochemistryFlorida Atlantic University 777 Glades Road Boca Raton FL 33431 USA
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6
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Liu H, Morris C, Lantz R, Kent TW, Elbassal EA, Wojcikiewicz EP, Du D. Residue-Specific Dynamics and Local Environmental Changes in Aβ40 Oligomer and Fibril Formation. Angew Chem Int Ed Engl 2018; 57:8017-8021. [PMID: 29750857 DOI: 10.1002/anie.201802490] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Indexed: 11/12/2022]
Abstract
Elucidating local dynamics of protein aggregation is crucial for understanding the mechanistic details of protein amyloidogenesis. Herein, we studied the residue-specific dynamics and local environmental changes of Aβ40 along the course of aggregation by using para-cyanophenylalanine (PheCN ) as a fluorescent and vibrational probe. Our results show that the PheCN residues introduced at various positions all exhibited an immediate decay of fluorescence intensity, indicating a relatively synergistic process in early oligomer formation. The fast decreases in the fluorescence intensities of residues 19 and 20 in the central hydrophobic core region and residue 10 in the N-terminal region suggest that they play crucial roles in the formation of the oligomeric core. The PheCN 4 residue exhibits a remarkably slower decrease in fluorescence intensity, implicating its dynamic conformational characteristics in oligomer and fibril formation. Our results also suggest that the N-terminal residues in fibrils are surrounded by a relatively hydrophobic local environment, as opposed to being solvated.
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Affiliation(s)
- Haiyang Liu
- Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
| | - Clifford Morris
- Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
| | - Richard Lantz
- Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
| | - Thomas W Kent
- Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
| | - Esmail A Elbassal
- Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
| | - Ewa P Wojcikiewicz
- Department of Biomedical Science, Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
| | - Deguo Du
- Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
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7
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Martin JP, Fetto NR, Tucker MJ. Comparison of biological chromophores: photophysical properties of cyanophenylalanine derivatives. Phys Chem Chem Phys 2018; 18:20750-7. [PMID: 27412819 DOI: 10.1039/c6cp04154j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Within this work, the family of cyanophenylalanine spectroscopic reporters is extended by showing the ortho and meta derivatives have intrinsic photophysical properties that are useful for studies of protein structure and dynamics. The molar absorptivities of 2-cyanophenylalanine and 3-cyanophenylalanine are shown to be comparable to that of 4-cyanophenylalanine with similar spectral features in their absorbance and emission profiles, demonstrating that these probes can be utilized interchangeably. The fluorescence quantum yields are also on the same scale as commonly used fluorophores in peptides and proteins, tyrosine and tryptophan. These new cyano-fluorophores can be paired with either 4-cyanophenylalanine or tryptophan to capture distances in peptide structure through Förster resonance energy transfer. Additionally, the spectroscopic properties of these chromophores can report the local solvent environment via changes in fluorescence emission intensity as a result of hydrogen bonding and/or hydration. A decrease in the quantum yield is also observed in basic environments due to photoinduced electron transfer from a deprotonated amine in the free PheCN species and at the N-terminus of a short peptide, providing an avenue to detect pH in biological systems. Our results show the potential of these probes, 2-cyanophenylalanine and 3-cyanophenylalanine, to be incorporated into a single peptide chain, either individually or in tandem with 4-cyanophenylalanine, tryptophan, or tyrosine, in order to obtain information about peptide structure and dynamics.
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Affiliation(s)
- Joshua P Martin
- Department of Chemistry, University of Nevada, Reno, 89557, USA.
| | - Natalie R Fetto
- Department of Chemistry, University of Nevada, Reno, 89557, USA.
| | - Matthew J Tucker
- Department of Chemistry, University of Nevada, Reno, 89557, USA.
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8
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Fetto NR, Cao W, Wallace IS, Tucker MJ. Selective Excitation of Cyanophenylalanine Fluorophores for Multi-Site Binding Studies. J Phys Chem B 2017; 121:9566-9571. [PMID: 28949137 DOI: 10.1021/acs.jpcb.7b08442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recently, it has been shown that nitrile-derivatized phenylalanines possess distinct fluorescent properties depending on the position of the cyano-group within the aromatic ring. These fluorophores have potential as probes for studying protein dynamics due to their sensitivity to local environment. Herein, we demonstrate that 2-cyanophenylalanine (Phe2CN) and Phe4CN can independently monitor multiple sites during the Ca2+ dependent binding of a skeletal muscle myosin light chain kinase (MLCK) peptide fragment to the protein calmodulin (CaM). These cyano-probes were incorporated at two different positions along the peptide chain and monitored simultaneously via selective excitation of the two chromophores. The peptide was labeled with Phe4CN at a residue known to bind to a hydrophobic binding pocket of CaM, while Phe2CN was designed to acquire dynamics external to the binding pocket. By selectively exciting each of the chromophores, it was determined that the fluorescence emission of Phe4CN located at position 581 of MLCK was quenched in the presence of CaM, while no significant change in Phe2CN emission was observed at exposed position 594. The CaM binding affinity (Kd) of the double labeled MLCK peptide was calculated to be approximately 64 nM, which is in agreement with previous measurements. These results indicate that multiple PheCN reporters within the same peptide can simultaneously detect variations in the local environment, and that these fluorophores could be utilized to investigate a wide variety of biological problems.
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Affiliation(s)
- Natalie R Fetto
- Department of Chemistry, University of Nevada , 1664 North Virginia Street, Reno, Nevada 89557, United States
| | - Wenqiang Cao
- Department of Chemistry, University of Nevada , 1664 North Virginia Street, Reno, Nevada 89557, United States
| | - Ian S Wallace
- Department of Chemistry, University of Nevada , 1664 North Virginia Street, Reno, Nevada 89557, United States.,Department of Biochemistry and Molecular Biology, University of Nevada , 1664 North Virginia Street, Reno, Nevada 89557, United States
| | - Matthew J Tucker
- Department of Chemistry, University of Nevada , 1664 North Virginia Street, Reno, Nevada 89557, United States
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9
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Watson MD, Peran I, Zou J, Bilsel O, Raleigh DP. Selenomethionine Quenching of Tryptophan Fluorescence Provides a Simple Probe of Protein Structure. Biochemistry 2017; 56:1085-1094. [DOI: 10.1021/acs.biochem.6b01000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthew D. Watson
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Ivan Peran
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Junjie Zou
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
- Laufer
Center for Physical and
Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, United States
| | - Osman Bilsel
- Department of Biochemistry and
Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Daniel P. Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
- Laufer
Center for Physical and
Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, United States
- Graduate Program in Biochemistry & Structural Biology, Stony Brook University, Stony Brook, New York 11794, United States
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10
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Peran I, Watson MD, Bilsel O, Raleigh DP. Selenomethionine, p-cyanophenylalanine pairs provide a convenient, sensitive, non-perturbing fluorescent probe of local helical structure. Chem Commun (Camb) 2016; 52:2055-8. [PMID: 26686928 DOI: 10.1039/c5cc08232c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The use of selenomethionine (MSe)-p-cyanophenylalanine (FCN) pairs to probe protein structure is demonstrated. MSe quenches FCN fluorescence via electron transfer. Both residues can be incorporated recombinantly or by peptide synthesis. Time-resolved and steady-state fluorescence measurements demonstrate that MSe-FCN pairs provide specific local probes of helical structure.
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Affiliation(s)
- Ivan Peran
- Department of Chemistry, Stony Brook University, Stony Brook, New York, 11794-3400, USA.
| | - Matthew D Watson
- Department of Chemistry, Stony Brook University, Stony Brook, New York, 11794-3400, USA.
| | - Osman Bilsel
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, Massachusetts 01605, USA
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, New York, 11794-3400, USA. and Graduate Program in Biochemistry & Structural Biology, Stony Brook University, Stony Brook, New York, 11794-3400, USA
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11
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Abedini A, Cao P, Raleigh DP. Detection of Helical Intermediates During Amyloid Formation by Intrinsically Disordered Polypeptides and Proteins. Methods Mol Biol 2016; 1345:55-66. [PMID: 26453205 DOI: 10.1007/978-1-4939-2978-8_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Amyloid formation and aberrant protein aggregation are hallmarks of more than 30 different human diseases. The proteins that form amyloid can be divided into two structural classes: those that form compact, well-ordered, globular structures in their unaggregated state and those that are intrinsically disordered in their unaggregated states. The latter include the Aβ peptide of Alzheimer's disease, islet amyloid polypeptide (IAPP, amylin) implicated in type 2 diabetes and α-synuclein, which is linked to Parkinson's disease. Work in the last 10 years has highlighted the potential role of pre-amyloid intermediates in cytotoxicity and has focused attention on their properties. A number of intrinsically disordered proteins appear to form helical intermediates during amyloid formation. We discuss the spectroscopic methods employed to detect and characterize helical intermediates in homogenous solution and in membrane-catalyzed amyloid formation, with the emphasis on the application of circular dichroism (CD). IAPP is used as an example, but the methods are generally applicable.
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Affiliation(s)
- Andisheh Abedini
- Division of Endocrinology, Diabetes and Metabolism, Diabetes Research Program, NYU School of Medicine, 550 First Avenue, Smilow 906, New York, NY, 10016, USA.
| | - Ping Cao
- Structural Biology Program, Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY, 10016, USA
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University, 647 Chemistry, Stony Brook, NY, 11794-3400, USA.
- Graduate Program in Biochemistry and Structural Biology, Stony Brook University, Stony Brook, NY, 11794-3400, USA.
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12
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Talukder P, Chen S, Roy B, Yakovchuk P, Spiering MM, Alam MP, Madathil MM, Bhattacharya C, Benkovic SJ, Hecht SM. Cyanotryptophans as Novel Fluorescent Probes for Studying Protein Conformational Changes and DNA–Protein Interaction. Biochemistry 2015; 54:7457-69. [DOI: 10.1021/acs.biochem.5b01085] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Poulami Talukder
- Center
for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Shengxi Chen
- Center
for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Basab Roy
- Center
for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Petro Yakovchuk
- Center
for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Michelle M. Spiering
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Mohammad P. Alam
- Center
for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Manikandadas M. Madathil
- Center
for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Chandrabali Bhattacharya
- Center
for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Stephen J. Benkovic
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sidney M. Hecht
- Center
for BioEnergetics, Biodesign Institute, and School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
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13
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Bobone S, De Zotti M, Bortolotti A, Biondi B, Ballano G, Palleschi A, Toniolo C, Formaggio F, Stella L. The fluorescence and infrared absorption probepara-cyanophenylalanine: Effect of labeling on the behavior of different membrane-interacting peptides. Biopolymers 2015; 104:521-32. [DOI: 10.1002/bip.22674] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/30/2015] [Accepted: 05/04/2015] [Indexed: 12/18/2022]
Affiliation(s)
- Sara Bobone
- Department of Chemical Sciences and Technologies; University of Rome Tor Vergata; 00133 Rome Italy
| | - Marta De Zotti
- Department of Chemistry; University of Padova; 35131 Padova Italy
| | - Annalisa Bortolotti
- Department of Chemical Sciences and Technologies; University of Rome Tor Vergata; 00133 Rome Italy
| | - Barbara Biondi
- Institute of Biomolecular Chemistry, Padova Unit, CNR; 35131 Padova Italy
| | - Gema Ballano
- Department of Chemistry; University of Padova; 35131 Padova Italy
| | - Antonio Palleschi
- Department of Chemical Sciences and Technologies; University of Rome Tor Vergata; 00133 Rome Italy
| | - Claudio Toniolo
- Department of Chemistry; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry, Padova Unit, CNR; 35131 Padova Italy
| | - Fernando Formaggio
- Department of Chemistry; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry, Padova Unit, CNR; 35131 Padova Italy
| | - Lorenzo Stella
- Department of Chemical Sciences and Technologies; University of Rome Tor Vergata; 00133 Rome Italy
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14
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Pazos IM, Ahmed IA, Berríos MIL, Gai F. Sensing pH via p-cyanophenylalanine fluorescence: Application to determine peptide pKa and membrane penetration kinetics. Anal Biochem 2015; 483:21-6. [PMID: 25935260 DOI: 10.1016/j.ab.2015.04.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 04/23/2015] [Accepted: 04/24/2015] [Indexed: 12/22/2022]
Abstract
We expand the spectroscopic utility of a well-known infrared and fluorescence probe, p-cyanophenylalanine, by showing that it can also serve as a pH sensor. This new application is based on the notion that the fluorescence quantum yield of this unnatural amino acid, when placed at or near the N-terminal end of a polypeptide, depends on the protonation status of the N-terminal amino group of the peptide. Using this pH sensor, we are able to determine the N-terminal pKa values of nine tripeptides and also the membrane penetration kinetics of a cell-penetrating peptide. Taken together, these examples demonstrate the applicability of using this unnatural amino acid fluorophore to study pH-dependent biological processes or events that accompany a pH change.
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Affiliation(s)
- Ileana M Pazos
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ismail A Ahmed
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
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15
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De Zotti M, Bobone S, Bortolotti A, Longo E, Biondi B, Peggion C, Formaggio F, Toniolo C, Dalla Bona A, Kaptein B, Stella L. 4-Cyano-α-methyl-l-phenylalanine as a Spectroscopic Marker for the Investigation of PeptaibioticMembrane Interactions. Chem Biodivers 2015; 12:513-27. [DOI: 10.1002/cbdv.201400404] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Indexed: 11/10/2022]
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16
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New aspects of the structure and mode of action of the human cathelicidin LL-37 revealed by the intrinsic probe p-cyanophenylalanine. Biochem J 2015; 465:443-57. [PMID: 25378136 DOI: 10.1042/bj20141016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The human cathelicidin peptide LL-37 is an important effector of our innate immune system and contributes to host defence with direct antimicrobial activity and immunomodulatory properties, and by stimulating wound healing. Its sequence has evolved to confer specific structural characteristics that strongly affect these biological activities, and differentiate it from orthologues of other primate species. In the present paper we report a detailed study of the folding and self-assembly of this peptide in comparison with rhesus monkey peptide RL-37, taking into account the different stages of its trajectory from bulk solution to contact with, and insertion into, biological membranes. Phenylalanine residues in different positions throughout the native sequences of LL-37 and RL-37 were systematically replaced with the non-invasive fluorescent and IR probe p-cyanophenylalanine. Steady-state and time-resolved fluorescence studies showed that LL-37, in contrast to RL-37, forms oligomers with a loose hydrophobic core in physiological solutions, which persist in the presence of biological membranes. Fourier transform IR and surface plasmon resonance studies also indicated different modes of interaction for LL-37 and RL-37 with anionic and neutral membranes. This correlated with a distinctly different mode of bacterial membrane permeabilization, as determined using a flow cytometric method involving impermeant fluorescent dyes linked to polymers of defined sizes.
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17
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Mintzer MR, Troxler T, Gai F. p-Cyanophenylalanine and selenomethionine constitute a useful fluorophore-quencher pair for short distance measurements: application to polyproline peptides. Phys Chem Chem Phys 2015; 17:7881-7. [PMID: 25716887 PMCID: PMC4357573 DOI: 10.1039/c5cp00050e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The C≡N stretching frequency and fluorescence quantum yield of p-cyanophenylalanine are sensitive to environment. As such, this unnatural amino acid has found broad applications, ranging from studying how proteins fold to determining the local electric field of membranes. Herein, we demonstrate that the fluorescence of p-cyanophenylalanine can be quenched by selenomethionine through an electron transfer process occurring at short distances, thus further expanding its spectroscopic utility. Using this fluorophore-quencher pair, we are able to show that short polyproline peptides (1-4 prolines) are not rigid; instead, they sample a bimodal conformational distribution.
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Affiliation(s)
- Mary Rose Mintzer
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Thomas Troxler
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
- The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
- The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, PA 19104
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18
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Abstract
Infrared spectroscopy has played an instrumental role in the study of a wide variety of biological questions. However, in many cases, it is impossible or difficult to rely on the intrinsic vibrational modes of biological molecules of interest, such as proteins, to reveal structural and environmental information in a site-specific manner. To overcome this limitation, investigators have dedicated many recent efforts to the development and application of various extrinsic vibrational probes that can be incorporated into biological molecules and used to site-specifically interrogate their structural or environmental properties. In this review, we highlight recent advancements in this rapidly growing research area.
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19
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Frisch H, Nie Y, Raunser S, Besenius P. pH‐Regulated Selectivity in Supramolecular Polymerizations: Switching between Co‐ and Homopolymers. Chemistry 2015; 21:3304-9. [DOI: 10.1002/chem.201406281] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Hendrik Frisch
- Organic Chemistry Institute and CeNTech, Westfälische Wilhelms‐Universität Münster, Corrensstrasse 40, 48149 Münster (Germany)
| | - Yan Nie
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto‐Hahn‐Strasse 11, 44227 Dortmund (Germany)
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto‐Hahn‐Strasse 11, 44227 Dortmund (Germany)
| | - Pol Besenius
- Organic Chemistry Institute and CeNTech, Westfälische Wilhelms‐Universität Münster, Corrensstrasse 40, 48149 Münster (Germany)
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20
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Liu H, Lantz R, Cosme P, Rivera N, Andino C, Gonzalez WG, Terentis AC, Wojcikiewicz EP, Oyola R, Miksovska J, Du D. Site-specific dynamics of amyloid formation and fibrillar configuration of Aβ1–23 using an unnatural amino acid. Chem Commun (Camb) 2015; 51:7000-3. [DOI: 10.1039/c5cc00149h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Distinct local dynamics of Aβ1–23 amyloid formation are characterized using an unnatural amino acid p-cyanophenylalanine as a spectroscopic probe.
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Affiliation(s)
- Haiyang Liu
- Department of Chemistry and Biochemistry
- Florida Atlantic University
- Boca Raton
- USA
| | - Richard Lantz
- Department of Chemistry and Biochemistry
- Florida Atlantic University
- Boca Raton
- USA
| | - Patrick Cosme
- Department of Chemistry and Biochemistry
- Florida Atlantic University
- Boca Raton
- USA
| | - Nelson Rivera
- Department of Chemistry
- University of Puerto Rico-Humacao
- Humacao
- Puerto Rico
| | - Carlos Andino
- Department of Chemistry
- University of Puerto Rico-Humacao
- Humacao
- Puerto Rico
| | - Walter G. Gonzalez
- Department of Chemistry and Biochemistry
- Florida International University
- Miami
- USA
| | - Andrew C. Terentis
- Department of Chemistry and Biochemistry
- Florida Atlantic University
- Boca Raton
- USA
| | | | - Rolando Oyola
- Department of Chemistry
- University of Puerto Rico-Humacao
- Humacao
- Puerto Rico
| | - Jaroslava Miksovska
- Department of Chemistry and Biochemistry
- Florida International University
- Miami
- USA
| | - Deguo Du
- Department of Chemistry and Biochemistry
- Florida Atlantic University
- Boca Raton
- USA
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21
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Maj M, Ahn C, Kossowska D, Park K, Kwak K, Han H, Cho M. β-Isocyanoalanine as an IR probe: comparison of vibrational dynamics between isonitrile and nitrile-derivatized IR probes. Phys Chem Chem Phys 2015; 17:11770-8. [DOI: 10.1039/c5cp00454c] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An infrared (IR) probe based on isonitrile (NC)-derivatized alanine 1 was synthesized and the vibrational properties of its NC stretching mode were investigated using FTIR and femtosecond IR pump–probe spectroscopy.
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Affiliation(s)
- Michał Maj
- Center for Molecular Spectroscopy and Dynamics
- Institute for Basic Science (IBS)
- Seoul 136-701, Korea
- Department of Chemistry
- Korea University
| | - Changwoo Ahn
- Department of Chemistry
- Korea University
- Seoul 136-701, Korea
| | - Dorota Kossowska
- Center for Molecular Spectroscopy and Dynamics
- Institute for Basic Science (IBS)
- Seoul 136-701, Korea
- Department of Chemistry
- Korea University
| | - Kwanghee Park
- Center for Molecular Spectroscopy and Dynamics
- Institute for Basic Science (IBS)
- Seoul 136-701, Korea
- Department of Chemistry
- Korea University
| | - Kyungwon Kwak
- Department of Chemistry
- Chung-Ang University
- Seoul 156-756, Korea
| | - Hogyu Han
- Department of Chemistry
- Korea University
- Seoul 136-701, Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics
- Institute for Basic Science (IBS)
- Seoul 136-701, Korea
- Department of Chemistry
- Korea University
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22
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Probing Microsecond Reactions with Microfluidic Mixers and TCSPC. SPRINGER SERIES IN CHEMICAL PHYSICS 2015. [DOI: 10.1007/978-3-319-14929-5_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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23
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Reif MM, Oostenbrink C. Molecular dynamics simulation of configurational ensembles compatible with experimental FRET efficiency data through a restraint on instantaneous FRET efficiencies. J Comput Chem 2014; 35:2319-32. [PMID: 25338770 DOI: 10.1002/jcc.23756] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 09/02/2014] [Accepted: 09/21/2014] [Indexed: 01/19/2023]
Abstract
Förster resonance energy transfer (FRET) measurements are widely used to investigate (bio)molecular interactions or/and association. FRET efficiencies, the primary data obtained from this method, give, in combination with the common assumption of isotropic chromophore orientation, detailed insight into the lengthscale of molecular phenomena. This study illustrates the application of a FRET efficiency restraint during classical atomistic molecular dynamics simulations of a mutant mastoparan X peptide in either water or 7 M aqueous urea. The restraint forces acting on the donor and acceptor chromophores ensure that the sampled peptide configurational ensemble satisfies the experimental primary data by modifying interchromophore separation and chromophore transition dipole moment orientations. By means of a conformational cluster analysis, it is seen that indeed different configurational ensembles may be sampled without and with application of the restraint. In particular, while the FRET efficiency and interchromophore distances monitored in an unrestrained simulation may differ from the experimentally-determined values, they can be brought in agreement with experimental data through usage of the FRET efficiency restraining potential. Furthermore, the present results suggest that the assumption of isotropic chromophore orientation is not always justified. The FRET efficiency restraint allows the generation of configurational ensembles that may not be accessible with unrestrained simulations, and thereby supports a meaningful interpretation of experimental FRET results in terms of the underlying molecular degrees of freedom. Thus, it offers an additional tool to connect the realms of computer and wet-lab experimentation.
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Affiliation(s)
- Maria M Reif
- Department of Material Sciences and Process Engineering, Institute for Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, Vienna
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24
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Meloni SL, Matsika S. Theoretical studies of the excited states of p-cyanophenylalanine and comparisons with the natural amino acids phenylalanine and tyrosine. Theor Chem Acc 2014. [DOI: 10.1007/s00214-014-1497-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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25
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Speight LC, Samanta M, Petersson EJ. Minimalist Approaches to Protein Labelling: Getting the Most Fluorescent Bang for Your Steric Buck. Aust J Chem 2014. [DOI: 10.1071/ch13554] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fluorescence methods allow one to monitor protein conformational changes, protein–protein associations, and proteolysis in real time, at the single molecule level and in living cells. The information gained in such experiments is a function of the spectroscopic techniques used and the strategic placement of fluorophore labels within the protein structure. There is often a trade-off between size and utility for fluorophores, whereby large size can be disruptive to the protein’s fold or function, but valuable characteristics, such as visible wavelength absorption and emission or brightness, require sizable chromophores. Three major types of fluorophore readouts are commonly used: (1) Förster resonance energy transfer (FRET); (2) photoinduced electron transfer (PET); and (3) environmental sensitivity. This review focuses on those probes small enough to be incorporated into proteins during ribosomal translation, which allows the probes to be placed on the interiors of proteins as they are folded during synthesis. The most broadly useful method for doing so is site-specific unnatural amino acid (UAA) mutagenesis. We discuss the use of UAA probes in applications relying on FRET, PET, and environmental sensitivity. We also briefly review other methods of protein labelling and compare their relative merits to UAA mutagenesis. Finally, we discuss small probes that have thus far been used only in synthetic peptides, but which have unusual value and may be candidates for incorporation using UAA methods.
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26
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Gonzalez JD, Levonyak NS, Schneider SC, Smith MJ, Cremeens ME. Using infrared spectroscopy of a nitrile labeled phenylalanine and tryptophan fluorescence to probe the α-MSH peptide’s side-chain interactions with a micelle model membrane. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2013.09.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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27
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Wissner RF, Batjargal S, Fadzen CM, Petersson EJ. Labeling proteins with fluorophore/thioamide Förster resonant energy transfer pairs by combining unnatural amino acid mutagenesis and native chemical ligation. J Am Chem Soc 2013; 135:6529-40. [PMID: 23594264 DOI: 10.1021/ja4005943] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have recently shown that p-cyanophenylalanine (Cnf) and a thioamide can be used as a minimally perturbing Förster resonant energy transfer (FRET) pair to monitor protein conformation. We have also shown that thioamide analogues of natural amino acids can be incorporated into full-sized proteins through native chemical ligation. For intermolecular studies with Cnf/thioamide FRET pairs, Cnf can be incorporated into proteins expressed in Escherichia coli through unnatural amino acid mutagenesis using a Cnf-specific tRNA synthetase. For intramolecular studies, a Cnf-labeled protein fragment can be expressed in E. coli and then ligated to a thioamide-labeled peptide synthesized on solid phase. This combination of methods allows for rapid access to double-labeled proteins with a minimum of unnecessary chemical synthesis. We demonstrate the utility of this approach by studying the binding of peptides to the protein calmodulin and by determining the orientation of the N- and C-termini in the amyloidogenic protein α-synuclein.
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Affiliation(s)
- Rebecca F Wissner
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA
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28
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Meng W, Luan B, Lyle N, Pappu RV, Raleigh DP. The Denatured State Ensemble Contains Significant Local and Long-Range Structure under Native Conditions: Analysis of the N-Terminal Domain of Ribosomal Protein L9. Biochemistry 2013; 52:2662-71. [DOI: 10.1021/bi301667u] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wenli Meng
- Department
of Chemistry, Stony Brook University, Stony
Brook, New York 11794-3400,
United States
| | - Bowu Luan
- Department
of Chemistry, Stony Brook University, Stony
Brook, New York 11794-3400,
United States
| | - Nicholas Lyle
- Department
of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive,
Campus Box 1097, St. Louis, Missouri 63130-4899, United States
| | - Rohit V. Pappu
- Department
of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive,
Campus Box 1097, St. Louis, Missouri 63130-4899, United States
| | - Daniel P. Raleigh
- Department
of Chemistry, Stony Brook University, Stony
Brook, New York 11794-3400,
United States
- Graduate Program in Biochemistry
and Structural Biology and Graduate Program in Biophysics, Stony Brook University, Stony Brook, New York 11794,
United States
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29
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Pandey AK, Naduthambi D, Thomas KM, Zondlo NJ. Proline editing: a general and practical approach to the synthesis of functionally and structurally diverse peptides. Analysis of steric versus stereoelectronic effects of 4-substituted prolines on conformation within peptides. J Am Chem Soc 2013; 135:4333-63. [PMID: 23402492 PMCID: PMC4209921 DOI: 10.1021/ja3109664] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Functionalized proline residues have diverse applications. Herein we describe a practical approach, proline editing, for the synthesis of peptides with stereospecifically modified proline residues. Peptides are synthesized by standard solid-phase peptide synthesis to incorporate Fmoc-hydroxyproline (4R-Hyp). In an automated manner, the Hyp hydroxyl is protected and the remainder of the peptide synthesized. After peptide synthesis, the Hyp protecting group is orthogonally removed and Hyp selectively modified to generate substituted proline amino acids, with the peptide main chain functioning to "protect" the proline amino and carboxyl groups. In a model tetrapeptide (Ac-TYPN-NH2), 4R-Hyp was stereospecifically converted to 122 different 4-substituted prolyl amino acids, with 4R or 4S stereochemistry, via Mitsunobu, oxidation, reduction, acylation, and substitution reactions. 4-Substituted prolines synthesized via proline editing include incorporated structured amino acid mimetics (Cys, Asp/Glu, Phe, Lys, Arg, pSer/pThr), recognition motifs (biotin, RGD), electron-withdrawing groups to induce stereoelectronic effects (fluoro, nitrobenzoate), handles for heteronuclear NMR ((19)F:fluoro; pentafluorophenyl or perfluoro-tert-butyl ether; 4,4-difluoro; (77)SePh) and other spectroscopies (fluorescence, IR: cyanophenyl ether), leaving groups (sulfonate, halide, NHS, bromoacetate), and other reactive handles (amine, thiol, thioester, ketone, hydroxylamine, maleimide, acrylate, azide, alkene, alkyne, aryl halide, tetrazine, 1,2-aminothiol). Proline editing provides access to these proline derivatives with no solution-phase synthesis. All peptides were analyzed by NMR to identify stereoelectronic and steric effects on conformation. Proline derivatives were synthesized to permit bioorthogonal conjugation reactions, including azide-alkyne, tetrazine-trans-cyclooctene, oxime, reductive amination, native chemical ligation, Suzuki, Sonogashira, cross-metathesis, and Diels-Alder reactions. These proline derivatives allowed three parallel bioorthogonal reactions to be conducted in one solution.
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Affiliation(s)
- Anil K. Pandey
- Department of Chemistry and Biochemistry, University of Delaware, Newark DE 19716
| | - Devan Naduthambi
- Department of Chemistry and Biochemistry, University of Delaware, Newark DE 19716
| | - Krista M. Thomas
- Department of Chemistry and Biochemistry, University of Delaware, Newark DE 19716
| | - Neal J. Zondlo
- Department of Chemistry and Biochemistry, University of Delaware, Newark DE 19716
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30
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Abstract
To expand the spectroscopic utility of the non-natural amino acid p-cyanophenylalanine (PheCN), we examine the quenching efficiencies of a series of commonly encountered anions toward its fluorescence. We find that iodide exhibits an unusually large Stern-Volmer quenching constant, making it a convenient choice in PheCN fluorescence quenching studies. Indeed, using the villin headpiece subdomain as a testbed we demonstrate that iodide quenching of PheCN fluorescence offers a convenient means to reveal protein conformational heterogeneity. Furthermore, we show that the amino group of PheCN strongly quenches its fluorescence, suggesting that PheCN could be used as a local pH sensor.
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31
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Du D, Liu H, Ojha B. Study protein folding and aggregation using nonnatural amino acid p-cyanophenylalanine as a sensitive optical probe. Methods Mol Biol 2013; 1081:77-89. [PMID: 24014435 DOI: 10.1007/978-1-62703-652-8_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Incorporation of nonnatural amino acids with a variety of special side groups into protein sequences has substantially expanded the experimental means of exploring protein structures and functions. Recently, p-cyanophenylalanine (PheCN), the nitrile analogue of phenylalanine, has been used as a novel optical probe for protein binding and folding studies. The fluorescence emission of PheCN is sensitive to solvent and local environment of the residue, making it a useful fluorescent probe of protein structural change at residue-specific resolution. Moreover, the utility of PheCN is increased by its ability to excite tryptophan fluorescence via the mechanism of fluorescence resonance energy transfer. PheCN could be applied to study a variety of biological problems, e.g., protein folding/unfolding and protein aggregation.
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Affiliation(s)
- Deguo Du
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, FL, USA
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32
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Serrano AL, Waegele MM, Gai F. Spectroscopic studies of protein folding: linear and nonlinear methods. Protein Sci 2012; 21:157-70. [PMID: 22109973 PMCID: PMC3324760 DOI: 10.1002/pro.2006] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 11/15/2011] [Indexed: 01/08/2023]
Abstract
Although protein folding is a simple outcome of the underlying thermodynamics, arriving at a quantitative and predictive understanding of how proteins fold nevertheless poses huge challenges. Therefore, both advanced experimental and computational methods are continuously being developed and refined to probe and reveal the atomistic details of protein folding dynamics and mechanisms. Herein, we provide a concise review of recent developments in spectroscopic studies of protein folding, with a focus on new triggering and probing methods. In particular, we describe several laser-based techniques for triggering protein folding/unfolding on the picosecond and/or nanosecond timescales and various linear and nonlinear spectroscopic techniques for interrogating protein conformations, conformational transitions, and dynamics.
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Affiliation(s)
- Arnaldo L Serrano
- Department of Chemistry, University of PennsylvaniaPhiladelphia, Pennsylvania 19104
| | - Matthias M Waegele
- Department of Chemistry, University of PennsylvaniaPhiladelphia, Pennsylvania 19104
| | - Feng Gai
- Department of Chemistry, University of PennsylvaniaPhiladelphia, Pennsylvania 19104
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33
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Cao P, Tu LH, Abedini A, Levsh O, Akter R, Patsalo V, Schmidt AM, Raleigh DP. Sensitivity of amyloid formation by human islet amyloid polypeptide to mutations at residue 20. J Mol Biol 2011; 421:282-95. [PMID: 22206987 DOI: 10.1016/j.jmb.2011.12.032] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 12/15/2011] [Accepted: 12/15/2011] [Indexed: 12/27/2022]
Abstract
Islet amyloid polypeptide (IAPP, amylin) is responsible for amyloid formation in type 2 diabetes and in islet cell transplants. The only known natural mutation found in mature human IAPP is a Ser20-to-Gly missense mutation, found with small frequency in Chinese and Japanese populations. The mutation appears to be associated with increased risk of early-onset type 2 diabetes. Early measurements in the presence of organic co-solvents showed that S20G-IAPP formed amyloid more quickly than the wild type. We confirm that the mutant accelerates amyloid formation under a range of conditions including in the absence of co-solvents. Ser20 adopts a normal backbone geometry, and the side chain makes no steric clashes in models of IAPP amyloid fibers, suggesting that the increased rate of amyloid formation by the mutant does not result from the relief of steric incompatibility in the fiber state. Transmission electronic microscopy, circular dichroism, and seeding studies were used to probe the structure of the resulting fibers. The S20G-IAPP peptide is toxic to cultured rat INS-1 (transformed rat insulinoma-1) β-cells. The sensitivity of amyloid formation to the identity of residue 20 was exploited to design a variant that is much slower to aggregate and that inhibits amyloid formation by wild-type IAPP. An S20K mutant forms amyloid with an 18-fold longer lag phase in homogeneous solution. Thioflavin T binding assays, together with experiments using a p-cyanophenylalanine (p-cyanoPhe) variant of human IAPP, show that the designed S20K mutant inhibits amyloid formation by human IAPP. The experiments illustrate how p-cyanoPhe can be exploited to monitor amyloid formation even in the presence of other amyloidogenic proteins.
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Affiliation(s)
- Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
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34
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Zheng S, Kwon I. Manipulation of enzyme properties by noncanonical amino acid incorporation. Biotechnol J 2011; 7:47-60. [PMID: 22121038 DOI: 10.1002/biot.201100267] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 08/22/2011] [Accepted: 09/22/2011] [Indexed: 11/07/2022]
Abstract
Since wild-type enzymes do not always have the properties needed for various applications, enzymes are often engineered to obtain desirable properties through protein engineering techniques. In the past decade, complementary to the widely used rational protein design and directed evolution techniques, noncanonical amino acid incorporation (NCAAI) has become a new and effective protein engineering technique. Recently, NCAAI has been used to improve intrinsic functions of proteins, such as enzymes and fluorescent proteins, beyond the capacities obtained with natural amino acids. Herein, recent progress on improving enzyme properties through NCAAI in vivo is reviewed and the challenges of current approaches and future directions are also discussed. To date, both NCAAI methods-residue- and site-specific incorporation-have been primarily used to improve the catalytic turnover number and substrate binding affinity of enzymes. Numerous strategies used to minimize structural perturbation and stability loss of a target enzyme upon NCAAI are also explored. Considering the generality of NCAAI incorporation, we expect its application could be expanded to improve other enzyme properties, such as substrate specificity and solvent resistance in the near future.
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Affiliation(s)
- Shun Zheng
- Department of Chemical Engineering University of Virginia, Charlottesville, VA 22904, USA
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35
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Affiliation(s)
- Howard C. Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, 1230 York Avenue, New York, NY 10065 (USA)
| | - Maurine E. Linder
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853 (USA)
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36
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Waegele MM, Culik RM, Gai F. Site-Specific Spectroscopic Reporters of the Local Electric Field, Hydration, Structure, and Dynamics of Biomolecules. J Phys Chem Lett 2011; 2:2598-2609. [PMID: 22003429 PMCID: PMC3192500 DOI: 10.1021/jz201161b] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Elucidating the underlying molecular mechanisms of protein folding and function is a very exciting and active research area, but poses significant challenges. This is due in part to the fact that existing experimental techniques are incapable of capturing snapshots along the 'reaction coordinate' in question with both sufficient spatial and temporal resolutions. In this regard, recent years have seen increased interests and efforts in development and employment of site-specific probes to enhance the structural sensitivity of spectroscopic techniques in conformational and dynamical studies of biological molecules. In particular, the spectroscopic and chemical properties of nitriles, thiocyanates, and azides render these groups attractive for the interrogation of complex biochemical constructs and processes. Here, we review their signatures in vibrational, fluorescence and NMR spectra and their utility in the context of elucidating chemical structure and dynamics of protein and DNA molecules.
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Affiliation(s)
| | | | - Feng Gai
- To whom correspondence should be addressed; ; Phone: 215-573-6256; Fax: 215-573-2112
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37
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Goldberg JM, Wissner RF, Klein AM, Petersson EJ. Thioamide quenching of intrinsic protein fluorescence. Chem Commun (Camb) 2011; 48:1550-2. [PMID: 21909546 DOI: 10.1039/c1cc14708k] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thioamides quench tryptophan and tyrosine fluorescence in a distance-dependent manner and thus can be used to monitor the binding of thioamide-containing peptides to proteins. Since thioamide analogs of the natural amino acids can be synthetically incorporated into peptides, they can function as minimally-perturbing probes of protein/peptide interactions.
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Affiliation(s)
- Jacob M Goldberg
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA
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Goldberg JM, Batjargal S, Petersson EJ. Thioamides as fluorescence quenching probes: minimalist chromophores to monitor protein dynamics. J Am Chem Soc 2011; 132:14718-20. [PMID: 20886849 DOI: 10.1021/ja1044924] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Decreasing the size of spectroscopic probes can afford higher-resolution structural information from fluorescence experiments. Therefore, we have developed p-cyanophenylalanine (Cnf) and backbone thioamides as a fluorophore/quencher pair. Through the examination of a series of thiopeptides, we have determined the working distance for this pair to be 8-30 Å. We have also carried out a proof-of-principle protein-folding experiment in which a Cnf/thioamide-labeled version of villin headpiece HP35 was thermally unfolded while the Cnf/thioamide distance was monitored by fluorescence. For a given protein, thioamide substitutions could be used to track motions with a much greater number of measurements than for current fluorescence probes, providing a dense array of data with which to model conformational changes.
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Affiliation(s)
- Jacob M Goldberg
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
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