1
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Cory MB, Li A, Hurley CM, Carman PJ, Pumroy RA, Hostetler ZM, Perez RM, Venkatesh Y, Li X, Gupta K, Petersson EJ, Kohli RM. The LexA-RecA* structure reveals a cryptic lock-and-key mechanism for SOS activation. Nat Struct Mol Biol 2024:10.1038/s41594-024-01317-3. [PMID: 38755298 DOI: 10.1038/s41594-024-01317-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 04/15/2024] [Indexed: 05/18/2024]
Abstract
The bacterial SOS response plays a key role in adaptation to DNA damage, including genomic stress caused by antibiotics. SOS induction begins when activated RecA*, an oligomeric nucleoprotein filament that forms on single-stranded DNA, binds to and stimulates autoproteolysis of the repressor LexA. Here, we present the structure of the complete Escherichia coli SOS signal complex, constituting full-length LexA bound to RecA*. We uncover an extensive interface unexpectedly including the LexA DNA-binding domain, providing a new molecular rationale for ordered SOS gene induction. We further find that the interface involves three RecA subunits, with a single residue in the central engaged subunit acting as a molecular key, inserting into an allosteric binding pocket to induce LexA cleavage. Given the pro-mutagenic nature of SOS activation, our structural and mechanistic insights provide a foundation for developing new therapeutics to slow the evolution of antibiotic resistance.
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Affiliation(s)
- Michael B Cory
- Graduate Group in Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | - Allen Li
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Christina M Hurley
- Graduate Group in Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | - Peter J Carman
- Graduate Group in Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | - Ruth A Pumroy
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Ryann M Perez
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Yarra Venkatesh
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Xinning Li
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Kushol Gupta
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | - E James Petersson
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA, USA.
| | - Rahul M Kohli
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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2
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Goettig P, Koch NG, Budisa N. Non-Canonical Amino Acids in Analyses of Protease Structure and Function. Int J Mol Sci 2023; 24:14035. [PMID: 37762340 PMCID: PMC10531186 DOI: 10.3390/ijms241814035] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 08/18/2023] [Accepted: 08/20/2023] [Indexed: 09/29/2023] Open
Abstract
All known organisms encode 20 canonical amino acids by base triplets in the genetic code. The cellular translational machinery produces proteins consisting mainly of these amino acids. Several hundred natural amino acids serve important functions in metabolism, as scaffold molecules, and in signal transduction. New side chains are generated mainly by post-translational modifications, while others have altered backbones, such as the β- or γ-amino acids, or they undergo stereochemical inversion, e.g., in the case of D-amino acids. In addition, the number of non-canonical amino acids has further increased by chemical syntheses. Since many of these non-canonical amino acids confer resistance to proteolytic degradation, they are potential protease inhibitors and tools for specificity profiling studies in substrate optimization and enzyme inhibition. Other applications include in vitro and in vivo studies of enzyme kinetics, molecular interactions and bioimaging, to name a few. Amino acids with bio-orthogonal labels are particularly attractive, enabling various cross-link and click reactions for structure-functional studies. Here, we cover the latest developments in protease research with non-canonical amino acids, which opens up a great potential, e.g., for novel prodrugs activated by proteases or for other pharmaceutical compounds, some of which have already reached the clinical trial stage.
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Affiliation(s)
- Peter Goettig
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria
| | - Nikolaj G. Koch
- Biocatalysis Group, Technische Universität Berlin, 10623 Berlin, Germany;
- Bioanalytics Group, Institute of Biotechnology, Technische Universität Berlin, 10623 Berlin, Germany;
| | - Nediljko Budisa
- Bioanalytics Group, Institute of Biotechnology, Technische Universität Berlin, 10623 Berlin, Germany;
- Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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3
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Cory MB, Jones CM, Shaffer KD, Venkatesh Y, Giannakoulias S, Perez RM, Lougee MG, Hummingbird E, Pagar VV, Hurley CM, Li A, Mach RH, Kohli RM, Petersson EJ. FRETing about the details: Case studies in the use of a genetically encoded fluorescent amino acid for distance-dependent energy transfer. Protein Sci 2023; 32:e4633. [PMID: 36974585 PMCID: PMC10108435 DOI: 10.1002/pro.4633] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 03/22/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023]
Abstract
Förster resonance energy transfer (FRET) is a valuable method for monitoring protein conformation and biomolecular interactions. Intrinsically fluorescent amino acids that can be genetically encoded, such as acridonylalanine (Acd), are particularly useful for FRET studies. However, quantitative interpretation of FRET data to derive distance information requires careful use of controls and consideration of photophysical effects. Here we present two case studies illustrating how Acd can be used in FRET experiments to study small molecule induced conformational changes and multicomponent biomolecular complexes.
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Affiliation(s)
- Michael B. Cory
- Graduate Group in Biochemistry and BiophysicsPerelman School of Medicine, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Chloe M. Jones
- Graduate Group in Biochemistry and BiophysicsPerelman School of Medicine, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Kyle D. Shaffer
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Yarra Venkatesh
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Sam Giannakoulias
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Ryann M. Perez
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Marshall G. Lougee
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Eshe Hummingbird
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Vinayak V. Pagar
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Christina M. Hurley
- Graduate Group in Biochemistry and BiophysicsPerelman School of Medicine, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Allen Li
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Robert H. Mach
- Department of RadiologyPerelman School of Medicine, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Rahul M. Kohli
- Department of Biochemistry and BiophysicsPerelman School of Medicine, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
- Department of MedicinePerelman School of Medicine, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - E. James Petersson
- Department of ChemistrySchool of Arts and Sciences, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
- Department of Biochemistry and BiophysicsPerelman School of Medicine, University of PennsylvaniaPhiladelphiaPennsylvania19104USA
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4
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Li M, Peng T. Genetic Encoding of a Fluorescent Noncanonical Amino Acid as a FRET Donor for the Analysis of Deubiquitinase Activities. Methods Mol Biol 2023; 2676:55-67. [PMID: 37277624 DOI: 10.1007/978-1-0716-3251-2_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The genetic code expansion technology enables the genetic encoding of fluorescent noncanonical amino acids (ncAAs) for site-specific fluorescent labeling of proteins. These co-translational and internal fluorescent tags have been harnessed to establish genetically encoded Förster resonance energy transfer (FRET) probes for studying protein structural changes and interactions. Here, we describe the protocols for site-specific incorporation of an aminocoumarin-derived fluorescent ncAA into proteins in E. coli and preparation of a fluorescent ncAA-based FRET probe for assaying the activities of deubiquitinases, a key class of enzymes involved in ubiquitination. We also describe the deployment of an in vitro fluorescence assay to screen and analyze small-molecule inhibitors against deubiquitinases.
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Affiliation(s)
- Manjia Li
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Tao Peng
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China.
- Institute of Chemical Biology, Shenzhen Bay Laboratory, Shenzhen, China.
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5
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Cory MB, Li A, Hurley CM, Hostetler ZM, Venkatesh Y, Jones CM, Petersson EJ, Kohli RM. Engineered RecA Constructs Reveal the Minimal SOS Activation Complex. Biochemistry 2022; 61:2884-2896. [PMID: 36473084 PMCID: PMC9982712 DOI: 10.1021/acs.biochem.2c00505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The SOS response is a bacterial DNA damage response pathway that has been heavily implicated in bacteria's ability to evolve resistance to antibiotics. Activation of the SOS response is dependent on the interaction between two bacterial proteins, RecA and LexA. RecA acts as a DNA damage sensor by forming lengthy oligomeric filaments (RecA*) along single-stranded DNA (ssDNA) in an ATP-dependent manner. RecA* can then bind to LexA, the repressor of SOS response genes, triggering LexA degradation and leading to induction of the SOS response. Formation of the RecA*-LexA complex therefore serves as the key "SOS activation signal." Given the challenges associated with studying a complex involving multiple macromolecular interactions, the essential constituents of RecA* that allow LexA cleavage are not well defined. Here, we leverage head-to-tail linked and end-capped RecA constructs as tools to define the minimal RecA* filament that can engage LexA. In contrast to previously postulated models, we found that as few as three linked RecA units are capable of ssDNA binding, LexA binding, and LexA cleavage. We further demonstrate that RecA oligomerization alone is insufficient for LexA cleavage, with an obligate requirement for ATP and ssDNA binding to form a competent SOS activation signal with the linked constructs. Our minimal system for RecA* highlights the limitations of prior models for the SOS activation signal and offers a novel tool that can inform efforts to slow acquired antibiotic resistance by targeting the SOS response.
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Affiliation(s)
- Michael B. Cory
- Graduate Group in Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Allen Li
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Christina M. Hurley
- Graduate Group in Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Zachary M. Hostetler
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Yarra Venkatesh
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Chloe M. Jones
- Graduate Group in Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - E. James Petersson
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Rahul M. Kohli
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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6
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Wang L, Hsiung CH, Liu X, Wang S, Loredo A, Zhang X, Xiao H. Xanthone-based solvatochromic fluorophores for quantifying micropolarity of protein aggregates. Chem Sci 2022; 13:12540-12549. [PMID: 36382293 PMCID: PMC9629104 DOI: 10.1039/d2sc05004h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 10/12/2022] [Indexed: 01/31/2023] Open
Abstract
Proper three-dimensional structures are essential for maintaining the functionality of proteins and for avoiding pathological consequences of improper folding. Misfolding and aggregation of proteins have been both associated with neurodegenerative disease. Therefore, a variety of fluorogenic tools that respond to both polarity and viscosity have been developed to detect protein aggregation. However, the rational design of highly sensitive fluorophores that respond solely to polarity has remained elusive. In this work, we demonstrate that electron-withdrawing heteroatoms with (d-p)-π* conjugation can stabilize lowest unoccupied molecular orbital (LUMO) energy levels and promote bathochromic shifts. Guided by computational analyses, we have devised a novel series of xanthone-based solvatochromic fluorophores that have rarely been systematically studied. The resulting probes exhibit superior sensitivity to polarity but are insensitive to viscosity. As proof of concept, we have synthesized protein targeting probes for live-cell confocal imaging intended to quantify the polarity of misfolded and aggregated proteins. Interestingly, our results reveal several layers of protein aggregates in a way that we had not anticipated. First, microenvironments with reduced polarity were validated in the misfolding and aggregation of folded globular proteins. Second, granular aggregates of AgHalo displayed a less polar environment than aggregates formed by folded globular protein represented by Htt-polyQ. Third, our studies reveal that granular protein aggregates formed in response to different types of stressors exhibit significant polarity differences. These results show that the solvatochromic fluorophores solely responsive to polarity represent a new class of indicators that can be widely used for detecting protein aggregation in live cells, thus paving the way for elucidating cellular mechanisms of protein aggregation as well as therapeutic approaches to managing intracellular aggregates.
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Affiliation(s)
- Lushun Wang
- Department of Chemistry, Rice University6100 Main StreetHoustonTexas77005USA
| | - Chia-Heng Hsiung
- Department of Chemistry, Pennsylvania State University, University ParkPA 16802USA,Department of Biochemistry and Molecular Biology, Pennsylvania State University, University ParkPA 16802USA
| | - Xiaojing Liu
- Department of Chemistry, Pennsylvania State University, University ParkPA 16802USA
| | - Shichao Wang
- Department of Chemistry, Rice University6100 Main StreetHoustonTexas77005USA
| | - Axel Loredo
- Department of Chemistry, Rice University6100 Main StreetHoustonTexas77005USA
| | - Xin Zhang
- Department of Chemistry, Pennsylvania State University, University ParkPA 16802USA,Department of Biochemistry and Molecular Biology, Pennsylvania State University, University ParkPA 16802USA
| | - Han Xiao
- Department of Chemistry, Rice University6100 Main StreetHoustonTexas77005USA,Department of Biosciences, Rice University6100 Main StreetHoustonTexas77005USA,Department of Bioengineering, Rice University6100 Main StreetHoustonTexas77005USA
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7
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Nanobodies targeting LexA autocleavage disclose a novel suppression strategy of SOS-response pathway. Structure 2022; 30:1479-1493.e9. [DOI: 10.1016/j.str.2022.09.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 06/29/2022] [Accepted: 09/18/2022] [Indexed: 11/05/2022]
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8
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Li M, Wang F, Yan L, Lu M, Zhang Y, Peng T. Genetically encoded fluorescent unnatural amino acids and FRET probes for detecting deubiquitinase activities. Chem Commun (Camb) 2022; 58:10186-10189. [PMID: 36000311 DOI: 10.1039/d2cc03623a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein we present the genetic encoding of 7-aminocoumarin-based lysine derivatives, ACouK and AFCouK, into proteins in both bacterial and mammalian cells and the characterization of FRET pairs comprising ACouK or AFCouK as the donor and GFP as the acceptor. We further report the application of the FRET pairs to construct fully genetically encoded ratiometric probes for detecting deubiquitinases and screening for inhibitors.
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Affiliation(s)
- Manjia Li
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Feifei Wang
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Long Yan
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Minghao Lu
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Yuqing Zhang
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Tao Peng
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China. .,Institute of Chemical Biology, Shenzhen Bay Laboratory, Shenzhen 518132, China
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9
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Jaramillo AVC, Cory MB, Li A, Kohli RM, Wuest WM. Exploration of inhibitors of the bacterial LexA repressor-protease. Bioorg Med Chem Lett 2022; 65:128702. [PMID: 35351585 DOI: 10.1016/j.bmcl.2022.128702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/17/2022] [Accepted: 03/24/2022] [Indexed: 11/25/2022]
Abstract
Resistant and tolerant bacterial infections lead to billions in healthcare costs and cause hundreds of thousands of deaths each year. The bulk of current antibiotic research efforts focus on molecules which, although novel, are not immune from acquired resistance and seldomly affect tolerant populations. The bacterial SOS response has been implicated in several resistance and tolerance mechanisms, making it an attractive antibiotic target. Using small molecule inhibitors targeting a key step in the deployment of the SOS response, our approach focused on preventing the deployment of mechanisms such as biofilm formation, horizontal gene transfer, and error-prone DNA repair. Herein we report the synthesis and testing of analogs of a triazole-containing tricyclic inhibitor of LexA proteolysis, the key event in the SOS response. Our results hint that our inhibitor's may function by adopting a β-hairpin conformation, reminiscent of the native cleavage loop of LexA.
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Affiliation(s)
| | - Michael B Cory
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Allen Li
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rahul M Kohli
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - William M Wuest
- Department of Chemistry, Emory University, Atlanta, GA, USA.
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10
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Aphicho K, Kittipanukul N, Uttamapinant C. Visualizing the complexity of proteins in living cells with genetic code expansion. Curr Opin Chem Biol 2022; 66:102108. [PMID: 35026612 DOI: 10.1016/j.cbpa.2021.102108] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/30/2021] [Accepted: 12/07/2021] [Indexed: 12/28/2022]
Abstract
Genetic code expansion has emerged as an enabling tool to provide insight into functions of understudied proteinogenic species, such as small proteins and peptides, and to probe protein biophysics in the cellular context. Here, we discuss recent technical advances and applications of genetic code expansion in cellular imaging of complex mammalian protein species, along with considerations and challenges on using the method.
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Affiliation(s)
- Kanokpol Aphicho
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Narongyot Kittipanukul
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Chayasith Uttamapinant
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand.
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11
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Zagotta WN, Sim BS, Nhim AK, Raza MM, Evans EG, Venkatesh Y, Jones CM, Mehl RA, Petersson EJ, Gordon SE. An improved fluorescent noncanonical amino acid for measuring conformational distributions using time-resolved transition metal ion FRET. eLife 2021; 10:e70236. [PMID: 34623258 PMCID: PMC8500717 DOI: 10.7554/elife.70236] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/09/2021] [Indexed: 11/30/2022] Open
Abstract
With the recent explosion in high-resolution protein structures, one of the next frontiers in biology is elucidating the mechanisms by which conformational rearrangements in proteins are regulated to meet the needs of cells under changing conditions. Rigorously measuring protein energetics and dynamics requires the development of new methods that can resolve structural heterogeneity and conformational distributions. We have previously developed steady-state transition metal ion fluorescence resonance energy transfer (tmFRET) approaches using a fluorescent noncanonical amino acid donor (Anap) and transition metal ion acceptor to probe conformational rearrangements in soluble and membrane proteins. Here, we show that the fluorescent noncanonical amino acid Acd has superior photophysical properties that extend its utility as a donor for tmFRET. Using maltose-binding protein (MBP) expressed in mammalian cells as a model system, we show that Acd is comparable to Anap in steady-state tmFRET experiments and that its long, single-exponential lifetime is better suited for probing conformational distributions using time-resolved FRET. These experiments reveal differences in heterogeneity in the apo and holo conformational states of MBP and produce accurate quantification of the distributions among apo and holo conformational states at subsaturating maltose concentrations. Our new approach using Acd for time-resolved tmFRET sets the stage for measuring the energetics of conformational rearrangements in soluble and membrane proteins in near-native conditions.
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Affiliation(s)
- William N Zagotta
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Brandon S Sim
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Anthony K Nhim
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Marium M Raza
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Eric Gb Evans
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Yarra Venkatesh
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Chloe M Jones
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania, Philadelphia, United States
| | - Ryan A Mehl
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, United States
| | - E James Petersson
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Sharona E Gordon
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
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12
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Jones CM, Robkis DM, Blizzard RJ, Munari M, Venkatesh Y, Mihaila TS, Eddins AJ, Mehl RA, Zagotta WN, Gordon SE, Petersson EJ. Genetic encoding of a highly photostable, long lifetime fluorescent amino acid for imaging in mammalian cells. Chem Sci 2021; 12:11955-11964. [PMID: 34976337 PMCID: PMC8634729 DOI: 10.1039/d1sc01914g] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 07/18/2021] [Indexed: 01/28/2023] Open
Abstract
Acridonylalanine (Acd) is a fluorescent amino acid that is highly photostable, with a high quantum yield and long fluorescence lifetime in water. These properties make it superior to existing genetically encodable fluorescent amino acids for monitoring protein interactions and conformational changes through fluorescence polarization or lifetime experiments, including fluorescence lifetime imaging microscopy (FLIM). Here, we report the genetic incorporation of Acd using engineered pyrrolysine tRNA synthetase (RS) mutants that allow for efficient Acd incorporation in both E. coli and mammalian cells. We compare protein yields and amino acid specificity for these Acd RSs to identify an optimal construct. We also demonstrate the use of Acd in FLIM, where its long lifetime provides strong contrast compared to endogenous fluorophores and engineered fluorescent proteins, which have lifetimes less than 5 ns.
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Affiliation(s)
- Chloe M Jones
- Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA 19104 USA
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania 3700 Hamilton Walk Philadelphia PA 19104 USA
| | - D Miklos Robkis
- Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA 19104 USA
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania 3700 Hamilton Walk Philadelphia PA 19104 USA
| | - Robert J Blizzard
- Department of Biochemistry and Biophysics, Oregon State University 2011 Ag Life Sciences Building Corvallis Oregon 97331 USA
| | - Mika Munari
- Department of Physiology and Biophysics, University of Washington 1705 NE Pacific St., Box 357290 Seattle WA 98195 USA
| | - Yarra Venkatesh
- Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA 19104 USA
| | - Tiberiu S Mihaila
- Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA 19104 USA
| | - Alex J Eddins
- Department of Biochemistry and Biophysics, Oregon State University 2011 Ag Life Sciences Building Corvallis Oregon 97331 USA
| | - Ryan A Mehl
- Department of Biochemistry and Biophysics, Oregon State University 2011 Ag Life Sciences Building Corvallis Oregon 97331 USA
| | - William N Zagotta
- Department of Physiology and Biophysics, University of Washington 1705 NE Pacific St., Box 357290 Seattle WA 98195 USA
| | - Sharona E Gordon
- Department of Physiology and Biophysics, University of Washington 1705 NE Pacific St., Box 357290 Seattle WA 98195 USA
| | - E James Petersson
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania 3700 Hamilton Walk Philadelphia PA 19104 USA
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13
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Giannakoulias S, Shringari SR, Ferrie JJ, Petersson EJ. Biomolecular simulation based machine learning models accurately predict sites of tolerability to the unnatural amino acid acridonylalanine. Sci Rep 2021; 11:18406. [PMID: 34526629 PMCID: PMC8443755 DOI: 10.1038/s41598-021-97965-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/17/2021] [Indexed: 11/08/2022] Open
Abstract
The incorporation of unnatural amino acids (Uaas) has provided an avenue for novel chemistries to be explored in biological systems. However, the successful application of Uaas is often hampered by site-specific impacts on protein yield and solubility. Although previous efforts to identify features which accurately capture these site-specific effects have been unsuccessful, we have developed a set of novel Rosetta Custom Score Functions and alternative Empirical Score Functions that accurately predict the effects of acridon-2-yl-alanine (Acd) incorporation on protein yield and solubility. Acd-containing mutants were simulated in PyRosetta, and machine learning (ML) was performed using either the decomposed values of the Rosetta energy function, or changes in residue contacts and bioinformatics. Using these feature sets, which represent Rosetta score function specific and bioinformatics-derived terms, ML models were trained to predict highly abstract experimental parameters such as mutant protein yield and solubility and displayed robust performance on well-balanced holdouts. Model feature importance analyses demonstrated that terms corresponding to hydrophobic interactions, desolvation, and amino acid angle preferences played a pivotal role in predicting tolerance of mutation to Acd. Overall, this work provides evidence that the application of ML to features extracted from simulated structural models allow for the accurate prediction of diverse and abstract biological phenomena, beyond the predictivity of traditional modeling and simulation approaches.
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Affiliation(s)
- Sam Giannakoulias
- Department of Chemistry, University of Pennsylvania, 231 S. 34th St, Philadelphia, PA, 19104, USA
| | - Sumant R Shringari
- Department of Chemistry, University of Pennsylvania, 231 S. 34th St, Philadelphia, PA, 19104, USA
| | - John J Ferrie
- Department of Molecular & Cell Biology, University of California, Berkeley, 475B Li Ka Shing Center, Berkeley, CA, 94720, USA.
| | - E James Petersson
- Department of Chemistry, University of Pennsylvania, 231 S. 34th St, Philadelphia, PA, 19104, USA.
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14
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Jones CM, Petersson GA, Petersson EJ. Synthesis and characterization of fluorescent amino acid dimethylaminoacridonylalanine. ARKIVOC 2021; 2021:97-109. [PMID: 33967634 PMCID: PMC8104435 DOI: 10.24820/ark.5550190.p011.498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Fluorescent amino acids are powerful biophysical tools as they can be used in structural or imaging studies of a given protein without significantly perturbing its native fold or function. Here, we have synthesized and characterized 7-(dimethylamino)acridon-2-ylalanine (Dad), a red-shifted derivative of the genetically-incorporable amino acid, acridon-2-ylalanine. Alkylation increases the quantum yield and fluorescence lifetime of Dad relative to a previously published amino acid, 7-aminoacridon-2-ylalanine (Aad). These properties of Dad make it a potentially valuable protein label, and we have performed initial testing of its ability to be genetically incorporated using an evolved aminoacyl tRNA synthetase.
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Affiliation(s)
- Chloe M Jones
- Department of Chemistry; University of Pennsylvania; 231 South 34th Street; Philadelphia, Pennsylvania 19104-6323, USA
- Biochemistry and Molecular Biophysics Graduate Group; University of Pennsylvania; 3700 Hamilton Walk, Philadelphia, PA 19104, USA
| | - George A Petersson
- Temple University Institute for Computational Molecular Science, 1925 N. 12th Street, Philadelphia, PA 19122, USA
| | - E James Petersson
- Department of Chemistry; University of Pennsylvania; 231 South 34th Street; Philadelphia, Pennsylvania 19104-6323, USA
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15
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Micikas R, Acharyya A, Gai F, Smith AB. A Scalable Synthesis of the Blue Fluorescent Amino Acid 4-Cyanotryptophan and the Fmoc Derivative: Utility Demonstrated with the Influenza M2 Peptide Tetramer. Org Lett 2021; 23:1247-1250. [DOI: 10.1021/acs.orglett.0c04055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert Micikas
- Department of Chemistry, University of Pennsylvania, 231 South 34th St, Philadelphia, Pennsylvania 19104, United States
| | - Arusha Acharyya
- Department of Chemistry, University of Pennsylvania, 231 South 34th St, Philadelphia, Pennsylvania 19104, United States
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, 231 South 34th St, Philadelphia, Pennsylvania 19104, United States
| | - Amos B. Smith
- Department of Chemistry, University of Pennsylvania, 231 South 34th St, Philadelphia, Pennsylvania 19104, United States
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