1
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Tang TMS, Luk LYP. Towards controlling activity of a peptide asparaginyl ligase (PAL) by lumazine synthetase compartmentalization. Faraday Discuss 2024. [PMID: 38832470 DOI: 10.1039/d4fd00002a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
Peptide asparaginyl ligases (PALs) hold significant potential in protein bioconjugation due to their excellent kinetic properties and broad substrate compatibility. However, realizing their full potential in biocatalytic applications requires precise control of their activity. Inspired by nature, we aimed to compartmentalize a representative PAL, OaAEP1-C247A, within protein containers to create artificial organelles with substrate sorting capability. Two encapsulation approaches were explored using engineered lumazine synthases (AaLS). The initial strategy involved tagging the PAL with a super-positively charged GFP(+36) for encapsulation into the super-negatively charged AaLS-13 variant, but it resulted in undesired truncation of the enzyme. The second approach involved genetic fusion of the OaAEP1-C247A with a circularly permutated AaLS variant (cpAaLS) and its co-production with AaLS-13, which successfully enabled compartmentalization of the PAL within a patch-work protein cage. Although the caged PAL retained its activity, it was significantly reduced compared to the free enzyme (∼30-40-fold), likely caused by issues related to OaAEP1-C247A stability and folding. Nevertheless, these findings demonstrated the feasibility of the AaLS encapsulation approach and encourage further optimization in the design of peptide-ligating artificial organelles in E. coli, aiming for a more effective and stable system for protein modifications.
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Affiliation(s)
- T M Simon Tang
- School of Chemistry & Cardiff Catalysis Institute, Cardiff University, Main Building, Room 1.54, Park Place, Cardiff, CF10 3AT, UK.
| | - Louis Y P Luk
- School of Chemistry & Cardiff Catalysis Institute, Cardiff University, Main Building, Room 1.54, Park Place, Cardiff, CF10 3AT, UK.
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2
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Rehm FBH, Tyler TJ, Zhou Y, Huang YH, Wang CK, Lawrence N, Craik DJ, Durek T. Repurposing a plant peptide cyclase for targeted lysine acylation. Nat Chem 2024:10.1038/s41557-024-01520-1. [PMID: 38789555 DOI: 10.1038/s41557-024-01520-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 03/25/2024] [Indexed: 05/26/2024]
Abstract
Transpeptidases are powerful tools for protein engineering but are largely restricted to acting at protein backbone termini. Alternative enzymatic approaches for internal protein labelling require bulky recognition motifs or non-proteinogenic reaction partners, potentially restricting which proteins can be modified or the types of modification that can be installed. Here we report a strategy for labelling lysine side chain ε-amines by repurposing an engineered asparaginyl ligase, which naturally catalyses peptide head-to-tail cyclization, for versatile isopeptide ligations that are compatible with peptidic substrates. We find that internal lysines with an adjacent leucine residue mimic the conventional N-terminal glycine-leucine substrate. This dipeptide motif enables efficient intra- or intermolecular ligation through internal lysine side chains, minimally leaving an asparagine C-terminally linked to the lysine side chain via an isopeptide bond. The versatility of this approach is demonstrated by the chemoenzymatic synthesis of peptides with non-native C terminus-to-side chain topology and the conjugation of chemically modified peptides to recombinant proteins.
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Affiliation(s)
- Fabian B H Rehm
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia.
| | - Tristan J Tyler
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Yan Zhou
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Yen-Hua Huang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Conan K Wang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Nicole Lawrence
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia.
| | - Thomas Durek
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia.
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3
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de Veer SJ, Zhou Y, Durek T, Craik DJ, Rehm FBH. Tertiary amide bond formation by an engineered asparaginyl ligase. Chem Sci 2024; 15:5248-5255. [PMID: 38577369 PMCID: PMC10988630 DOI: 10.1039/d3sc06352f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 03/04/2024] [Indexed: 04/06/2024] Open
Abstract
Transpeptidases are powerful tools for site-specific protein modification, enabling the production of tailored biologics to investigate protein function and aiding the development of next-generation therapeutics and diagnostics. Although protein labelling at the N- or C-terminus is readily accomplished using a range of established transpeptidases, these reactions are generally limited to forming products that are linked by a standard (secondary) amide bond. Here we show that, unlike other widely used transpeptidases, an engineered asparaginyl ligase is able to efficiently synthesise tertiary amide bonds by accepting diverse secondary amine nucleophiles. These reactions proceed efficiently under mild conditions (near-neutral pH) and allow the optimal recognition elements for asparaginyl ligases (P1 Asn and P2'' Leu) to be preserved. Certain products, particularly proline-containing products, were found to be protected from recognition by the enzyme, allowing for straightforward sequential labelling of proteins. Additionally, incorporation of 4-azidoproline enables one-pot dual labelling directly at the ligation junction. These capabilities further expand the chemical diversity of asparaginyl ligase-catalysed reactions and provide an alternative approach for straightforward, successive modification of protein substrates.
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Affiliation(s)
- Simon J de Veer
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland Brisbane QLD 4072 Australia
| | - Yan Zhou
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland Brisbane QLD 4072 Australia
| | - Thomas Durek
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland Brisbane QLD 4072 Australia
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland Brisbane QLD 4072 Australia
| | - Fabian B H Rehm
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland Brisbane QLD 4072 Australia
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4
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Arnott ZLP, Morgan HE, Hollingsworth K, Stevenson CME, Collins LJ, Tamasanu A, Machin DC, Dolan JP, Kamiński TP, Wildsmith GC, Williamson DJ, Pickles IB, Warriner SL, Turnbull WB, Webb ME. Quantitative N- or C-Terminal Labelling of Proteins with Unactivated Peptides by Use of Sortases and a d-Aminopeptidase. Angew Chem Int Ed Engl 2024; 63:e202310862. [PMID: 38072831 DOI: 10.1002/anie.202310862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Indexed: 01/13/2024]
Abstract
Quantitative and selective labelling of proteins is widely used in both academic and industrial laboratories, and catalytic labelling of proteins using transpeptidases, such as sortases, has proved to be a popular strategy for such selective modification. A major challenge for this class of enzymes is that the majority of procedures require an excess of the labelling reagent or, alternatively, activated substrates rather than simple commercially sourced peptides. We report the use of a coupled enzyme strategy which enables quantitative N- and C-terminal labelling of proteins using unactivated labelling peptides. The use of an aminopeptidase in conjunction with a transpeptidase allows sequence-specific degradation of the peptide by-product, shifting the equilibrium to favor product formation, which greatly enhances the reaction efficiency. Subsequent optimisation of the reaction allows N-terminal labelling of proteins using essentially equimolar ratios of peptide label to protein and C-terminal labelling with only a small excess. Minimizing the amount of substrate required for quantitative labelling has the potential to improve industrial processes and facilitate the use of transpeptidation as a method for protein labelling.
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Affiliation(s)
- Zoe L P Arnott
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
- Present address: Centre for Process Innovation, Central Park, The Nigel Perry Building, 1 Union St, Darlington, DL1 1GL, United Kingdom
| | - Holly E Morgan
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
- Present Address: Ashfield MedComms, City Tower, Piccadilly Plaza, Manchester, M1 4BT, United Kingdom
| | - Kristian Hollingsworth
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Charlotte M E Stevenson
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Lawrence J Collins
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Alexandra Tamasanu
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Darren C Machin
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Jonathan P Dolan
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
- Present Address: School of Chemical and Physical Sciences & Centre for Glycoscience Research and Training, Keele University, Keele, Staffordshire, ST5 5BG, United Kingdom
| | - Tomasz P Kamiński
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Gemma C Wildsmith
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Daniel J Williamson
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
- Present Address: Iksuda Therapeutics, The Biosphere, Draymans Way, Newcastle upon Tyne, NE4 5BX, United Kingdom
| | - Isabelle B Pickles
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
- Present Address: York Structural Biology Laboratory, Department of Biology, University of York, Heslington, York, YO10 5DD, United Kingdom
| | - Stuart L Warriner
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - W Bruce Turnbull
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Michael E Webb
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
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5
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Lu Z, Ge R, Zheng B, Zheng P. Enzymatic Protein Immobilization for Nanobody Array. Molecules 2024; 29:366. [PMID: 38257279 PMCID: PMC10820937 DOI: 10.3390/molecules29020366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 01/02/2024] [Accepted: 01/08/2024] [Indexed: 01/24/2024] Open
Abstract
Antibody arrays play a pivotal role in the detection and quantification of biomolecules, with their effectiveness largely dependent on efficient protein immobilization. Traditional methods often use heterobifunctional cross-linking reagents for attaching functional residues in proteins to corresponding chemical groups on the substrate surface. However, this method does not control the antibody's anchoring point and orientation, potentially leading to reduced binding efficiency and overall performance. Another method using anti-antibodies as intermediate molecules to control the orientation can be used but it demonstrates lower efficiency. Here, we demonstrate a site-specific protein immobilization strategy utilizing OaAEP1 (asparaginyl endopeptidase) for building a nanobody array. Moreover, we used a nanobody-targeting enhanced green fluorescent protein (eGFP) as the model system to validate the protein immobilization method for building a nanobody array. Finally, by rapidly enriching eGFP, this method further highlights its potential for rapid diagnostic applications. This approach, characterized by its simplicity, high efficiency, and specificity, offers an advancement in the development of surface-modified protein arrays. It promises to enhance the sensitivity and accuracy of biomolecule detection, paving the way for broader applications in various research and diagnostic fields.
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Affiliation(s)
| | | | | | - Peng Zheng
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China; (Z.L.); (R.G.); (B.Z.)
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6
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Liu G, Gao F, Yang X, Zhang J, Yang S, Li Y, Liu L. Aggregation-induced emission for the detection of peptide ligases with improving ligation efficiency. Anal Chim Acta 2023; 1284:341994. [PMID: 37996157 DOI: 10.1016/j.aca.2023.341994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/26/2023] [Accepted: 11/01/2023] [Indexed: 11/25/2023]
Abstract
BACKGROUND Monitoring peptide ligase activity is of great significance for biological research, medical diagnosis, and drug discovery. The current methods for the detection of peptide ligases suffer from the limitations of high background signal, elaborate design of substrate, and high reversibility of ligation reaction. In this work, we proposed a simple and sensitive method for ligase detection with reducing ligation reversibility on the basis of aggregation-induced emission (AIE) mechanism. RESULTS The peptide probes labeled with AIE luminogens (AIEgens) were water-soluble and emitted weak fluorescence. After ligation reaction, the enzymatic products with AIEgens showed high hydrophobicity and could readily assembly into aggregates, thus lighting up the fluorescence. More interestingly, the formation of aggregates pushed the equilibrium to the generation of the desired ligation products, thus improving the catalytic efficiency by driving the reaction towards completion. The ligation reaction conversion rate (>80 %) is significantly higher than that without blocking the reversibility with additional treatment. With sortase A (SrtA) as the analyte example, the detection limit of this method was found to be 0.01 nM with a linear range of 0-50 nM. The system was applied to evaluate the inhibition efficiency of berberine chloride and quercetin and determine the activity of SrtA in serum, lysate and Staphylococcus aureus with satisfactory results. SIGNIFICANCE This study indicated that the ligation efficiency and detection sensitivity can be improved by reducing ligation reversibility through AIE phenomenon. The proposed strategy could be used for the detection of other peptide ligases by adopting sequence-specific peptide substrates.
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Affiliation(s)
- Gang Liu
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan, 455000, PR China; College of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou, Henan, 450001, PR China
| | - Fengli Gao
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan, 455000, PR China
| | - Xiupei Yang
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan, 455000, PR China
| | - Jingyi Zhang
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan, 455000, PR China
| | - Suling Yang
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan, 455000, PR China
| | - Yuanyuan Li
- College of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou, Henan, 450001, PR China.
| | - Lin Liu
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan, 455000, PR China.
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7
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Zeng Y, Shi W, Liu Z, Xu H, Liu L, Hang J, Wang Y, Lu M, Zhou W, Huang W, Tang F. C-terminal modification and functionalization of proteins via a self-cleavage tag triggered by a small molecule. Nat Commun 2023; 14:7169. [PMID: 37935692 PMCID: PMC10630284 DOI: 10.1038/s41467-023-42977-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 10/24/2023] [Indexed: 11/09/2023] Open
Abstract
The precise modification or functionalization of the protein C-terminus is essential but full of challenges. Herein, a chemical approach to modify the C-terminus is developed by fusing a cysteine protease domain on the C-terminus of the protein of interest, which could achieve the non-enzymatic C-terminal functionalization by InsP6-triggered cysteine protease domain self-cleavage. This method demonstrates a highly efficient way to achieve protein C-terminal functionalization and is compatible with a wide range of amine-containing molecules and proteins. Additionally, a reversible C-terminal de-functionalization is found by incubating the C-terminal modified proteins with cysteine protease domain and InsP6, providing a tool for protein functionalization and de-functionalization. Last, various applications of protein C-terminal functionalization are provided in this work, as demonstrated by the site-specific assembly of nanobody drug conjugates, the construction of a bifunctional antibody, the C-terminal fluorescent labeling, and the C-terminal transpeptidation and glycosylation.
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Affiliation(s)
- Yue Zeng
- State Key Laboratory of Drug Research, Center for Biotherapeutics Discovery Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, No.555 Zuchongzhi Rd, Pudong, Shanghai, 201203, China
- University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
| | - Wei Shi
- State Key Laboratory of Drug Research, Center for Biotherapeutics Discovery Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, No.555 Zuchongzhi Rd, Pudong, Shanghai, 201203, China
| | - Zhi Liu
- State Key Laboratory of Drug Research, Center for Biotherapeutics Discovery Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, No.555 Zuchongzhi Rd, Pudong, Shanghai, 201203, China
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, No. 138 Xianlin Rd, Nanjing, 210023, China
| | - Hao Xu
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, No. 138 Xianlin Rd, Nanjing, 210023, China
| | - Liya Liu
- State Key Laboratory of Drug Research, Center for Biotherapeutics Discovery Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, No.555 Zuchongzhi Rd, Pudong, Shanghai, 201203, China
| | - Jiaying Hang
- State Key Laboratory of Drug Research, Center for Biotherapeutics Discovery Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, No.555 Zuchongzhi Rd, Pudong, Shanghai, 201203, China
| | - Yongqin Wang
- School of Pharmaceutical Science and Technology, Hangzhou Institute of Advanced Study, Hangzhou, 310024, China
| | - Mengru Lu
- School of Pharmaceutical Science and Technology, Hangzhou Institute of Advanced Study, Hangzhou, 310024, China
| | - Wei Zhou
- School of Pharmaceutical Science and Technology, Hangzhou Institute of Advanced Study, Hangzhou, 310024, China
| | - Wei Huang
- State Key Laboratory of Drug Research, Center for Biotherapeutics Discovery Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, No.555 Zuchongzhi Rd, Pudong, Shanghai, 201203, China
- University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, No. 138 Xianlin Rd, Nanjing, 210023, China
- School of Pharmaceutical Science and Technology, Hangzhou Institute of Advanced Study, Hangzhou, 310024, China
| | - Feng Tang
- State Key Laboratory of Drug Research, Center for Biotherapeutics Discovery Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, No.555 Zuchongzhi Rd, Pudong, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China.
- School of Pharmaceutical Science and Technology, Hangzhou Institute of Advanced Study, Hangzhou, 310024, China.
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8
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Alexander AK, Elshahawi SI. Promiscuous Enzymes for Residue-Specific Peptide and Protein Late-Stage Functionalization. Chembiochem 2023; 24:e202300372. [PMID: 37338668 PMCID: PMC10496146 DOI: 10.1002/cbic.202300372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/20/2023] [Accepted: 06/20/2023] [Indexed: 06/21/2023]
Abstract
The late-stage functionalization of peptides and proteins holds significant promise for drug discovery and facilitates bioorthogonal chemistry. This selective functionalization leads to innovative advances in in vitro and in vivo biological research. However, it is a challenging endeavor to selectively target a certain amino acid or position in the presence of other residues containing reactive groups. Biocatalysis has emerged as a powerful tool for selective, efficient, and economical modifications of molecules. Enzymes that have the ability to modify multiple complex substrates or selectively install nonnative handles have wide applications. Herein, we highlight enzymes with broad substrate tolerance that have been demonstrated to modify a specific amino acid residue in simple or complex peptides and/or proteins at late-stage. The different substrates accepted by these enzymes are mentioned together with the reported downstream bioorthogonal reactions that have benefited from the enzymatic selective modifications.
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Affiliation(s)
- Ashley K Alexander
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Rinker Health Science Campus, Irvine, CA 92618, USA
| | - Sherif I Elshahawi
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Rinker Health Science Campus, Irvine, CA 92618, USA
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9
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Abstract
A variant originated from Oldenlandia affinis asparaginyl ligase, OaAEP1-C247A, has emerged as an ideal tool for protein labeling. However, its preparation was laborious and time-consuming. It is recombinantly produced as a zymogen, requiring acid activation and four chromatographic steps; despite these extensive steps, the catalytically active enzyme exhibited only moderate purity. Here, we report a novel preparation protocol, in which the cap and catalytically active core domains are produced as separate entities. The active enzyme can be obtained in two chromatographic steps, immobilized metal affinity chromatography (IMAC) and size exclusion chromatography (SEC), with no acid activation required, thereby shortening the purification procedure from at least 2 days to less than 6 h. In addition to the original C247A mutation which enhanced reaction with various amino nucleophiles, an extra D29E mutation was introduced to prevent self-cleavage, which led to noticeable improvements in homogeneity and activity of the enzyme. Indeed, the resulting "split AEP" (i.e., core domain of OaAEP1-D29E/C247A) exhibited improved catalytic efficiency constant (kcat/KM) that was found to be ∼3-fold higher than that of the original acid-activated counterpart (OaAEP1-C247A). Furthermore, we described a protein labeling protocol that couples the enzymatic reaction with an irreversible chemical transformation, thereby enabling high conversion of labeled protein with a lowered amount of reagent. Precisely, an alternative Asn-Cys-Leu (NCL) recognition sequence was used for substrate recognition. As the byproduct contains an N-terminal cysteine, it can be transformed into an inert 1,2 aminothiol motif by reacting with formylphenyl boronic acid (FPBA). Finally, the opportunities and challenges associated with the use of asparaginyl ligase are discussed.
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Affiliation(s)
- Muge Ma
- School of Chemistry, Cardiff University, Park Place, Cardiff, United Kingdom
| | - Simon T M Tang
- School of Chemistry, Cardiff University, Park Place, Cardiff, United Kingdom
| | - Matthew T Dickerson
- School of Chemistry, Cardiff University, Park Place, Cardiff, United Kingdom
| | - Louis Y P Luk
- School of Chemistry, Cardiff University, Park Place, Cardiff, United Kingdom.
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