1
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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2
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Tian S, de Veer SJ, Durek T, Wang CK, Craik DJ. Nucleation of a key beta-turn promotes cyclotide oxidative folding. J Biol Chem 2024; 300:107125. [PMID: 38432638 PMCID: PMC10999817 DOI: 10.1016/j.jbc.2024.107125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 02/05/2024] [Accepted: 02/19/2024] [Indexed: 03/05/2024] Open
Abstract
Cyclotides are plant-derived peptides characterized by a head-to-tail cyclic backbone and a cystine knot motif comprised of three disulfide bonds. Formation of this motif via in vitro oxidative folding can be challenging and can result in misfolded isomers with nonnative disulfide connectivities. Here, we investigated the effect of β-turn nucleation on cyclotide oxidative folding. Two types of β-turn mimics were grafted into kalata B1, individually replacing each of the four β-turns in the folded cyclotide. Insertion of d-Pro-Gly into loop 5 was beneficial to the folding of both cyclic kB1 and a linear form of the peptide. The linear grafted analog folded four-times faster in aqueous conditions than cyclic kB1 in optimized conditions. Additionally, the cyclic analogue folded without the need for redox agents by transitioning through a native-like intermediate that was on-pathway to product formation. Kalata B1 is from the Möbius subfamily of cyclotides. Grafting d-Pro-Gly into loop 5 of cyclotides from two other subfamilies also had a beneficial effect on folding. Our findings demonstrate the importance of a β-turn nucleation site for cyclotide oxidative folding, which could be adopted as a chemical strategy to improve the in vitro folding of diverse cystine-rich peptides.
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Affiliation(s)
- Sixin Tian
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - 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, 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
| | - 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
| | - 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.
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3
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Tian S, Durek T, Wang CK, Zdenek CN, Fry BG, Craik DJ, de Veer SJ. Engineering the Cyclization Loop of MCoTI-II Generates Targeted Cyclotides that Potently Inhibit Factor XIIa. J Med Chem 2022; 65:15698-15709. [PMID: 36383928 DOI: 10.1021/acs.jmedchem.2c01080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Factor XIIa (FXIIa) is a promising target for developing new drugs that prevent thrombosis without causing bleeding complications. A native cyclotide (MCoTI-II) is gaining interest for engineering FXIIa-targeted anticoagulants as this peptide inhibits FXIIa but not other coagulation proteases. Here, we engineered the native biosynthetic cyclization loop of MCoTI-II (loop 6) to generate improved FXIIa inhibitors. Decreasing the loop length led to gains in potency up to 7.7-fold, with the most potent variant having five residues in loop 6 (Ki = 25 nM). We subsequently examined sequence changes within loop 6 and an adjacent loop, with substitutions at P4 and P2' producing a potent FXIIa inhibitor (Ki = 2 nM) that displayed more than 700-fold selectivity, was stable in human serum, and blocked the intrinsic coagulation pathway in human plasma. These findings demonstrate that engineering the biosynthetic cyclization loop can generate improved cyclotide variants, expanding their potential for drug discovery.
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Affiliation(s)
- Sixin Tian
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 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, Queensland 4072, 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 4072, Australia
| | - Christina N Zdenek
- Venom Evolution Lab, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Bryan G Fry
- Venom Evolution Lab, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 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, Queensland 4072, Australia
| | - 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, Queensland 4072, Australia
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4
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Li CY, Rehm FBH, Yap K, Zdenek CN, Harding MD, Fry BG, Durek T, Craik DJ, de Veer SJ. Cystine Knot Peptides with Tuneable Activity and Mechanism. Angew Chem Int Ed Engl 2022; 61:e202200951. [PMID: 35224831 PMCID: PMC9539897 DOI: 10.1002/anie.202200951] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Indexed: 11/17/2022]
Abstract
Knottins are topologically complex peptides that are stabilised by a cystine knot and have exceptionally diverse functions, including protease inhibition. However, approaches for tuning their activity in situ are limited. Here, we demonstrate separate approaches for tuning the activity of knottin protease inhibitors using light or streptavidin. We show that the inhibitory activity and selectivity of an engineered knottin can be controlled with light by activating a second mode of action that switches the inhibitor ON against new targets. Guided by a knottin library screen, we also identify a position in the inhibitor's binding loop that permits insertion of a biotin tag without impairing activity. Using streptavidin, biotinylated knottins with nanomolar affinity can be switched OFF in activity assays, and the anticoagulant activity of a factor XIIa inhibitor can be rapidly switched OFF in human plasma. Our findings expand the scope of engineered knottins for precisely controlling protein function.
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Affiliation(s)
- Choi Yi Li
- 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
| | - Kuok Yap
- 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
| | - Christina N Zdenek
- Venom Evolution Lab, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Maxim D Harding
- 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
| | - Bryan G Fry
- Venom Evolution Lab, School of Biological Sciences, 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
| | - 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
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5
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Abstract
Transpeptidase‐catalyzed protein and peptide modifications have been widely utilized for generating conjugates of interest for biological investigation or therapeutic applications. However, all known transpeptidases are constrained to ligating in the N‐to‐C orientation, limiting the scope of attainable products. Here, we report that an engineered asparaginyl ligase accepts diverse incoming nucleophile substrate mimetics, particularly when a means of selectively quenching the reactivity of byproducts released from the recognition sequence is employed. In addition to directly catalyzing formation of l‐/d‐ or α‐/β‐amino acid junctions, we find C‐terminal Leu‐ethylenediamine (Leu‐Eda) motifs to be bona fide mimetics of native N‐terminal Gly‐Leu sequences. Appending a C‐terminal Leu‐Eda to synthetic peptides or, via an intein‐splicing approach, to recombinant proteins enables direct transpeptidase‐catalyzed C‐to‐C ligations. This work significantly expands the synthetic scope of enzyme‐catalyzed protein transpeptidation reactions.
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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, QLD 4072, 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, QLD 4072, Australia
| | - 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
| | - 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
| | - 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
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6
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Rehm FBH, Tyler TJ, de Veer SJ, Craik DJ, Durek T. Enzymatic C‐to‐C Protein Ligation. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202116672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Fabian B. H. Rehm
- The University of Queensland Institute for Molecular Bioscience Chemistry and Structural Biology AUSTRALIA
| | - Tristan J. Tyler
- The University of Queensland Institute for Molecular Bioscience Chemistry and Structural Biology AUSTRALIA
| | - Simon J. de Veer
- The University of Queensland Institute for Molecular Bioscience Chemistry and Structural Biology AUSTRALIA
| | - David J. Craik
- The University of Queensland Institute for Molecular Bioscience Chemistry and Structural Biology AUSTRALIA
| | - Thomas Durek
- The University of Queensland Institute for Molecular Bioscience 306 Carmody RdLvl 7 North 4072 Brisbane AUSTRALIA
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7
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Abstract
Chemoenzymatic protein and peptide modification is a powerful means of generating defined, homogeneous conjugates for a range of applications. However, the use of transpeptidases is limited by the need to prepare synthetic peptide conjugates to be ligated, bulky recognition tags remaining in the product, and inefficient substrate turnover. Here, we report a peptide/protein labeling strategy that utilizes a promiscuous, engineered transpeptidase to irreversibly incorporate diverse, commercially available amines at a C-terminal asparagine. To demonstrate the utility of this approach, we prepare a protein-drug conjugate, generate a genetically inaccessible C-to-C protein fusion, and site specifically label both termini of a single protein in sequential steps.
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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, QLD 4072, 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, QLD 4072, Australia
| | - Kuok Yap
- 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
| | - 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
| | - 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
| | - 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
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8
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Liu W, de Veer SJ, Huang YH, Sengoku T, Okada C, Ogata K, Zdenek CN, Fry BG, Swedberg JE, Passioura T, Craik DJ, Suga H. An Ultrapotent and Selective Cyclic Peptide Inhibitor of Human β-Factor XIIa in a Cyclotide Scaffold. J Am Chem Soc 2021; 143:18481-18489. [PMID: 34723512 DOI: 10.1021/jacs.1c07574] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cyclotides are plant-derived peptides with complex structures shaped by their head-to-tail cyclic backbone and cystine knot core. These structural features underpin the native bioactivities of cyclotides, as well as their beneficial properties as pharmaceutical leads, including high proteolytic stability and cell permeability. However, their inherent structural complexity presents a challenge for cyclotide engineering, particularly for accessing libraries of sufficient chemical diversity to design potent and selective cyclotide variants. Here, we report a strategy using mRNA display enabling us to select potent cyclotide-based FXIIa inhibitors from a library comprising more than 1012 members based on the cyclotide scaffold of Momordica cochinchinensis trypsin inhibitor-II (MCoTI-II). The most potent and selective inhibitor, cMCoFx1, has a pM inhibitory constant toward FXIIa with greater than three orders of magnitude selectivity over related serine proteases, realizing specific inhibition of the intrinsic coagulation pathway. The cocrystal structure of cMCoFx1 and FXIIa revealed interactions at several positions across the contact interface that conveyed high affinity binding, highlighting that such cyclotides are attractive cystine knot scaffolds for therapeutic development.
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Affiliation(s)
- Wenyu Liu
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Simon J de Veer
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Brisbane, QLD 4072, Australia.,Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Yen-Hua Huang
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Brisbane, QLD 4072, Australia.,Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Toru Sengoku
- Department of Biochemistry, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa 236-0004, Japan
| | - Chikako Okada
- Department of Biochemistry, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa 236-0004, Japan
| | - Kazuhiro Ogata
- Department of Biochemistry, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa 236-0004, Japan
| | - Christina N Zdenek
- Venom Evolution Lab, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Bryan G Fry
- Venom Evolution Lab, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Joakim E Swedberg
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Toby Passioura
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Brisbane, QLD 4072, Australia.,School of Life and Environmental Sciences, School of Chemistry and Sydney Analytical, The University of Sydney, Sydney, NSW 2006, Australia
| | - David J Craik
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Brisbane, QLD 4072, Australia.,Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Brisbane, QLD 4072, Australia
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9
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Durek T, Kaas Q, White AM, Weidmann J, Fuaad AA, Cheneval O, Schroeder CI, de Veer SJ, Dellsén A, Österlund T, Larsson N, Knerr L, Bauer U, Plowright AT, Craik DJ. Melanocortin 1 Receptor Agonists Based on a Bivalent, Bicyclic Peptide Framework. J Med Chem 2021; 64:9906-9915. [PMID: 34197114 DOI: 10.1021/acs.jmedchem.1c00095] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have designed a new class of highly potent bivalent melanocortin receptor ligands based on the nature-derived bicyclic peptide sunflower trypsin inhibitor 1 (SFTI-1). Incorporation of melanotropin pharmacophores in each of the two turn regions of SFTI-1 resulted in substantial gains in agonist activity particularly at human melanocortin receptors 1 and 3 (hMC1R/hMC3R) compared to monovalent analogues. In in vitro binding and functional assays, the most potent molecule, compound 6, displayed low picomolar agonist activity at hMC1R (pEC50 > 10.3; EC50 < 50 pM; pKi: 10.16 ± 0.04; Ki: 69 ± 5 pM) and is at least 30-fold more selective for this receptor than for hMC3R, hMC4R, or hMC5R. The results are discussed in the context of structural homology models of hMCRs in complex with the developed bivalent ligands.
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Affiliation(s)
- 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
| | - Quentin Kaas
- 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
| | - Andrew M White
- 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
| | - Joachim Weidmann
- 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
| | - Abdullah Ahmad Fuaad
- 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
| | - Olivier Cheneval
- 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
| | - Christina I Schroeder
- 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
| | - 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
| | - Anita Dellsén
- Mechanistic Biology & Profiling, Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg 43183, Mölndal, Sweden
| | - Torben Österlund
- Discovery Biology, Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg 43183, Mölndal, Sweden.,Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg 43183, Mölndal, Sweden
| | - Niklas Larsson
- Discovery Biology, Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg 43183, Mölndal, Sweden
| | - Laurent Knerr
- Medicinal Chemistry, Cardiovascular and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg 43183, Mölndal, Sweden
| | - Udo Bauer
- Medicinal Chemistry, Cardiovascular and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg 43183, Mölndal, Sweden
| | - Alleyn T Plowright
- Medicinal Chemistry, Cardiovascular and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg 43183, Mölndal, Sweden
| | - 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
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10
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de Veer SJ, White AM, Craik DJ. Sunflower Trypsin Inhibitor-1 (SFTI-1): Sowing Seeds in the Fields of Chemistry and Biology. Angew Chem Int Ed Engl 2020; 60:8050-8071. [PMID: 32621554 DOI: 10.1002/anie.202006919] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Indexed: 12/24/2022]
Abstract
Nature-derived cyclic peptides have proven to be a vast source of inspiration for advancing modern pharmaceutical design and synthetic chemistry. The focus of this Review is sunflower trypsin inhibitor-1 (SFTI-1), one of the smallest disulfide-bridged cyclic peptides found in nature. SFTI-1 has an unusual biosynthetic pathway that begins with a dual-purpose albumin precursor and ends with the production of a high-affinity serine protease inhibitor that rivals other inhibitors much larger in size. Investigations on the molecular basis for SFTI-1's rigid structure and adaptable function have planted seeds for thought that have now blossomed in several different fields. Here we survey these applications to highlight the growing potential of SFTI-1 as a versatile template for engineering inhibitors, a prototypic peptide for studying inhibitory mechanisms, a stable scaffold for grafting bioactive peptides, and a model peptide for evaluating peptidomimetic motifs and platform technologies.
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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
| | - Andrew M White
- 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
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11
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Li CY, Yap K, Swedberg JE, Craik DJ, de Veer SJ. Binding Loop Substitutions in the Cyclic Peptide SFTI-1 Generate Potent and Selective Chymase Inhibitors. J Med Chem 2020; 63:816-826. [PMID: 31855419 DOI: 10.1021/acs.jmedchem.9b01811] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Chymase is a serine protease that is predominantly expressed by mast cells and has key roles in immune defense and the cardiovascular system. This enzyme has also emerged as a therapeutic target for cardiovascular disease due to its ability to remodel cardiac tissue and generate angiotensin II. Here, we used the nature-derived cyclic peptide sunflower trypsin inhibitor-1 (SFTI-1) as a template for designing novel chymase inhibitors. The key binding contacts of SFTI-1 were optimized by combining a peptide substrate library screen with structure-based design, which yielded several variants with potent activity. The lead variant was further modified by replacing the P1 Tyr residue with para-substituted Phe derivatives, generating new inhibitors with improved potency (Ki = 1.8 nM) and higher selectivity over closely related enzymes. Several variants were shown to block angiotensin I cleavage in vitro, highlighting their potential for further development and future evaluation as pharmaceutical leads.
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Affiliation(s)
- Choi Yi Li
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia
| | - Kuok Yap
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia
| | - Joakim E Swedberg
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia
| | - David J Craik
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia
| | - Simon J de Veer
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia
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12
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Abstract
This Review explores the class of plant-derived macrocyclic peptides called cyclotides. We include an account of their discovery, characterization, and distribution in the plant kingdom as well as a detailed analysis of their sequences and structures, biosynthesis and chemical synthesis, biological functions, and applications. These macrocyclic peptides are around 30 amino acids in size and are characterized by their head-to-tail cyclic backbone and cystine knot motif, which render them to be exceptionally stable, with resistance to thermal or enzymatic degradation. Routes to their chemical synthesis have been developed over the past two decades, and this capability has facilitated a wide range of mutagenesis and structure-activity relationship studies. In turn, these studies have both led to an increased understanding of their mechanisms of action as well as facilitated a range of applications in agriculture and medicine, as ecofriendly crop protection agents, and as drug leads or scaffolds for pharmaceutical design. Our overall objective in this Review is to provide readers with a comprehensive overview of cyclotides that we hope will stimulate further work on this fascinating family of peptides.
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Affiliation(s)
- Simon J de Veer
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Meng-Wei Kan
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - David J Craik
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
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13
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Tian S, Swedberg JE, Li CY, Craik DJ, de Veer SJ. Iterative Optimization of the Cyclic Peptide SFTI-1 Yields Potent Inhibitors of Neutrophil Proteinase 3. ACS Med Chem Lett 2019; 10:1234-1239. [PMID: 31413811 DOI: 10.1021/acsmedchemlett.9b00253] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 07/19/2019] [Indexed: 12/12/2022] Open
Abstract
Neutrophils produce at least four serine proteases that are packaged within azurophilic granules. These enzymes contribute to antimicrobial defense and inflammation but can be destructive if their activities are not properly regulated. Accordingly, they represent therapeutic targets for several diseases, including chronic obstructive pulmonary disease, cystic fibrosis, and rheumatoid arthritis. In this study, we focused on proteinase 3 (PR3), a neutrophil protease with elastase-like specificity, and engineered potent PR3 inhibitors based on the cyclic peptide sunflower trypsin inhibitor-1 (SFTI-1). We used an iterative optimization approach to screen targeted substitutions at the P1, P2, P2', and P4 positions of SFTI-1, and generated several new inhibitors with K i values in the low nanomolar range. These SFTI-variants show high stability in human serum and are attractive leads for further optimization.
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Affiliation(s)
- Sixin Tian
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Joakim E. Swedberg
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Choi Yi Li
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David J. Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Simon J. de Veer
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
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14
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Riley BT, Ilyichova O, de Veer SJ, Swedberg JE, Wilson E, Hoke DE, Harris JM, Buckle AM. KLK4 Inhibition by Cyclic and Acyclic Peptides: Structural and Dynamical Insights into Standard-Mechanism Protease Inhibitors. Biochemistry 2019; 58:2524-2533. [PMID: 31058493 DOI: 10.1021/acs.biochem.9b00191] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Sunflower trypsin inhibitor (SFTI-1) is a 14 amino acid serine protease inhibitor. The dual antiparallel β-sheet arrangement of SFTI-1 is stabilized by an N-terminal-C-terminal backbone cyclization and a further disulfide bridge to form a final bicyclic structure. This constrained structure is further rigidified by an extensive network of internal hydrogen bonds. Thus, the structure of SFTI-1 in solution resembles the protease-bound structure, reducing the entropic penalty upon protease binding. When cleaved at the scissile bond, it is thought that the rigidifying features of SFTI-1 maintain its structure, allowing the scissile bond to be reformed. The lack of structural plasticity for SFTI-1 is proposed to favor initial protease binding and continued occupancy in the protease active site, resulting in an equilibrium between the cleaved and uncleaved inhibitor in the presence of a protease. We have determined, at 1.15 Å resolution, the X-ray crystal structures of complexes between human kallikrein-related peptidase 4 (KLK4) and SFTI-FCQR(Asn14) and between KLK4 and an acyclic form of the same inhibitor, SFTI-FCQR(Asn14)[1,14], with the latter displaying a cleaved scissile bond. Structural analysis and MD simulations together reveal the roles of the altered contact sequence, intramolecular hydrogen bonding network, and backbone cyclization in altering the state of SFTI's scissile bond ligation at the protease active site. Taken together, the data presented reveal insights into the role of dynamics in the standard-mechanism inhibition and suggest that modifications on the non-contact strand may be a useful, underexplored approach for generating further potent or selective SFTI-based inhibitors against members of the serine protease family.
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Affiliation(s)
- Blake T Riley
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
| | - Olga Ilyichova
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
| | - Simon J de Veer
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Joakim E Swedberg
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Emily Wilson
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
| | - David E Hoke
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
| | - Jonathan M Harris
- Institute of Health and Biomedical Innovation , Queensland University of Technology , Brisbane , Queensland 4059 , Australia
| | - Ashley M Buckle
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
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15
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Li CY, de Veer SJ, White AM, Chen X, Harris JM, Swedberg JE, Craik DJ. Amino Acid Scanning at P5' within the Bowman-Birk Inhibitory Loop Reveals Specificity Trends for Diverse Serine Proteases. J Med Chem 2019; 62:3696-3706. [PMID: 30888159 DOI: 10.1021/acs.jmedchem.9b00211] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sunflower trypsin inhibitor-1 (SFTI-1) is a 14-amino acid cyclic peptide that shares an inhibitory loop with a sequence and structure similar to a larger family of serine protease inhibitors, the Bowman-Birk inhibitors. Here, we focus on the P5' residue in the Bowman-Birk inhibitory loop and produce a library of SFTI variants to characterize the P5' specificity of 11 different proteases. We identify seven amino acids that are generally preferred by these enzymes and also correlate with P5' sequence diversity in naturally occurring Bowman-Birk inhibitors. Additionally, we show that several enzymes have divergent specificities that can be harnessed in engineering studies. By optimizing the P5' residue, we improve the potency or selectivity of existing inhibitors for kallikrein-related peptidase 5 and show that a variant with substitutions at 7 of the scaffold's 14 residues retains a similar structure to SFTI-1. These findings provide new insights into P5' specificity requirements for the Bowman-Birk inhibitory loop.
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Affiliation(s)
- Choi Yi Li
- Institute for Molecular Bioscience , The University of Queensland , Brisbane QLD 4072 , Australia
| | - Simon J de Veer
- Institute for Molecular Bioscience , The University of Queensland , Brisbane QLD 4072 , Australia
| | - Andrew M White
- Institute for Molecular Bioscience , The University of Queensland , Brisbane QLD 4072 , Australia
| | - Xingchen Chen
- Institute of Health and Biomedical Innovation , Queensland University of Technology , Brisbane QLD 4059 , Australia
| | - Jonathan M Harris
- Institute of Health and Biomedical Innovation , Queensland University of Technology , Brisbane QLD 4059 , Australia
| | - Joakim E Swedberg
- Institute for Molecular Bioscience , The University of Queensland , Brisbane QLD 4072 , Australia
| | - David J Craik
- Institute for Molecular Bioscience , The University of Queensland , Brisbane QLD 4072 , Australia
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16
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Swedberg JE, Ghani HA, Harris JM, de Veer SJ, Craik DJ. Potent, Selective, and Cell-Penetrating Inhibitors of Kallikrein-Related Peptidase 4 Based on the Cyclic Peptide MCoTI-II. ACS Med Chem Lett 2018; 9:1258-1262. [PMID: 30613336 DOI: 10.1021/acsmedchemlett.8b00422] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 11/21/2018] [Indexed: 12/11/2022] Open
Abstract
Kallikrein-related peptidase 4 (KLK4) is a serine protease that has putative intracellular and extracellular functions in prostate cancer progression. Here we show that MCoTI-II, a 34-amino acid cyclic peptide found in the seeds of red gac (Momordica cochinchinensis), is an inhibitor of KLK4. By grafting a preferred KLK4 cleavage sequence into MCoTI-II, we produced a highly potent KLK4 inhibitor (K i = 0.1 nM) that displayed 100,000-fold selectivity over related KLKs and the ability to penetrate cells. Additionally, by substituting positively charged noncontact residues in this compound, we produced a potent and selective KLK4 inhibitor that does not penetrate cells. The inhibitors were shown to be nontoxic to human cells and stable in human serum. These KLK4 inhibitors provide useful chemical tools to further define the role(s) of both intracellular and extracellular KLK4 in prostate cancer cell lines and disease models.
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Affiliation(s)
- Joakim E. Swedberg
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Hafiza Abdul Ghani
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jonathan M. Harris
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - Simon J. de Veer
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David J. Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
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17
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Li CY, de Veer SJ, Law RHP, Whisstock JC, Craik DJ, Swedberg JE. Characterising the Subsite Specificity of Urokinase-Type Plasminogen Activator and Tissue-Type Plasminogen Activator using a Sequence-Defined Peptide Aldehyde Library. Chembiochem 2018; 20:46-50. [PMID: 30225958 DOI: 10.1002/cbic.201800395] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/05/2018] [Indexed: 01/08/2023]
Abstract
Urokinase-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) are two serine proteases that contribute to initiating fibrinolysis by activating plasminogen. uPA is also an important tumour-associated protease due to its role in extracellular matrix remodelling. Overexpression of uPA has been identified in several different cancers and uPA inhibition has been reported as a promising therapeutic strategy. Although several peptide-based uPA inhibitors have been developed, the extent to which uPA tolerates different tetrapeptide sequences that span the P1-P4 positions remains to be thoroughly explored. In this study, we screened a sequence-defined peptide aldehyde library against uPA and tPA. Preferred sequences from the library screen yielded potent inhibitors for uPA, led by Ac-GTAR-H (Ki =18 nm), but not for tPA. Additionally, synthetic peptide substrates corresponding to preferred inhibitor sequences were cleaved with high catalytic efficiency by uPA but not by tPA. These findings provide new insights into the binding specificity of uPA and tPA and the relative activity of tetrapeptide inhibitors and substrates against these enzymes.
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Affiliation(s)
- Choi Yi Li
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Simon J de Veer
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Ruby H P Law
- Department of Biochemistry and Molecular Biology, Biomedical Discovery Institute, Monash University, Melbourne, VIC, 3800, Australia
| | - James C Whisstock
- Department of Biochemistry and Molecular Biology, Biomedical Discovery Institute, Monash University, Melbourne, VIC, 3800, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Joakim E Swedberg
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
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18
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de Veer SJ, Li CY, Swedberg JE, Schroeder CI, Craik DJ. Engineering potent mesotrypsin inhibitors based on the plant-derived cyclic peptide, sunflower trypsin inhibitor-1. Eur J Med Chem 2018; 155:695-704. [PMID: 29936356 DOI: 10.1016/j.ejmech.2018.06.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/24/2018] [Accepted: 06/12/2018] [Indexed: 12/19/2022]
Abstract
Plants produce a diverse range of peptides and proteins that inhibit the activity of different serine proteases. The value of these inhibitors not only stems from their native role(s) in planta, but they are also regarded as promising templates for inhibitor engineering. Interest in this field has grown rapidly in recent years, particularly for therapeutic applications. The serine protease mesotrypsin has been implicated in several cancers, but is a challenging target for inhibitor engineering as a number of serine protease inhibitors that typically display broad-range activity show limited activity against mesotrypsin. In this study, we use a cyclic peptide isolated from sunflower seeds, sunflower trypsin inhibitor-1 (SFTI-1), as a scaffold for engineering potent mesotrypsin inhibitors. SFTI-1 comprises 14-amino acids and is a potent inhibitor of human cationic trypsin (Ki = 30 ± 0.8 pM) but shows 165,000-fold weaker activity against mesotrypsin (Ki = 4.96 ± 0.2 μM). Using an inhibitor library based on SFTI-1, we show that the inhibitor's P2' residue (Ile) is a key contributor to SFTI-1's limited activity against mesotrypsin. Substituting P2' Ile with chemically diverse amino acids, including non-canonical aromatic residues, produced new inhibitor variants that maintained a similar structure to SFTI-1 and showed marked improvements in activity (exceeding 100-fold). An assessment of the activity of the new inhibitors against closely-related trypsin paralogs revealed that the improved activity against mesotrypsin was accompanied by a loss in activity against off-target proteases, such that several engineered variants showed comparable activity against mesotrypsin and human cationic trypsin. Together, these findings identify potent mesotrypsin inhibitors that are suitable for further optimisation studies and demonstrate the potential gains in activity and selectivity that can be achieved by optimising the P2' residue, particularly for engineered SFTI-based inhibitors.
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Affiliation(s)
- Simon J de Veer
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Choi Yi Li
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Joakim E Swedberg
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Christina I Schroeder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.
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19
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Abstract
Among the various molecules that plants produce for defense against pests and pathogens, cyclotides stand out as exceptionally stable and structurally unique. These ribosomally synthesized peptides are around 30 amino acids in size, and are stabilized by a head-to-tail cyclic peptide backbone and three disulfide bonds that form a cystine knot. They occur in certain plants of the Rubiaceae, Violaceae, Cucurbitaceae, Fabaceae, and Solanaceae families, with an individual plant producing up to hundreds of different cyclotides. Aside from being exploitable as crop protection agents based on their natural pesticidal activities, cyclotides are amenable to repurposing by chemists for use as drug leads or as tools in chemical biology. Their macrocyclic peptide backbone and knotted arrangement of three disulfide bonds engenders cyclotides with resistance to proteolytic degradation, high temperatures, and chemical chaotropes. Furthermore, their small size makes them accessible to synthesis using solid-phase peptide chemistry and so non-natural cyclotides can be designed and synthesized for a variety of applications. Our focus here is on cyclotides as tools in chemical biology, and there are four main areas of application that have appeared in the literature so far: (i) cyclotides as probes of membrane binding; (ii) cyclotides as probes of biosynthetic pathways for peptide cyclization; (iii) cyclotides as probes of protease specificity and function; and (iv) cyclotides as probes of receptor binding and specificity, with the potential for them to be developed as drug leads. The main methods used in these studies include solid-phase peptide chemistry for synthesis and NMR spectroscopy for structural characterization, as well as a wide range of biochemical and biophysical techniques for probing intermolecular interactions. In addition, cyclotides have been examined in diverse biological assays, ranging from enzyme inhibition to cell penetration, intracellular targeting and cytotoxicity. The main finding to have emerged from studies over the past decade is that cyclotides are exceptionally stable under a variety of conditions (in assay buffers, biological fluids, membranes, and recombinant expression systems). Furthermore, they are structurally very well-defined and amenable to sequence substitutions that can introduce new desired biological activities, generally without compromising their exceptional stability. Both features contribute to their use as peptide-based frameworks in drug design. Finally, they occupy a size niche between traditional small-molecule drugs (<500 Da in molecular weight) and protein-based biologics (>5000 Da) and thus can probe receptors, membranes, and protein-protein interactions in different ways to what is possible with either small molecules or biologics. Overall, cyclotides are an exciting class of peptides that have great potential as ultrastable chemical biology probes in a variety of applications. They have the advantage of specificity (typical of proteins) combined with the synthetic accessibility of small molecules.
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Affiliation(s)
- Simon J. de Veer
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Joachim Weidmann
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - David J. Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
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20
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Swedberg JE, Li CY, de Veer SJ, Wang CK, Craik DJ. Design of Potent and Selective Cathepsin G Inhibitors Based on the Sunflower Trypsin Inhibitor-1 Scaffold. J Med Chem 2017; 60:658-667. [PMID: 28045523 DOI: 10.1021/acs.jmedchem.6b01509] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neutrophils are directly responsible for destroying invading pathogens via reactive oxygen species, antimicrobial peptides, and neutrophil serine proteases (NSPs). Imbalance between NSP activity and endogenous protease inhibitors is associated with chronic inflammatory disorders, and engineered inhibitors of NSPs are a potential therapeutic pathway. In this study we characterized the extended substrate specificity (P4-P1) of the NSP cathepsin G using a peptide substrate library. Substituting preferred cathepsin G substrate sequences into sunflower trypsin inhibitor-1 (SFTI-1) produced a potent cathepsin G inhibitor (Ki = 0.89 nM). Cathepsin G's P2' preference was determined by screening against a P2' diverse SFTI-based library, and the most preferred residue at P2' was combined in SFTI-1 with a preferred substrate sequence (P4-P2) and a nonproteinogenic P1 residue (4-guanidyl-l-phenylalanine) to produce a potent (Ki = 1.6 nM) and the most selective (≥360-fold) engineered cathepsin G inhibitor reported to date. This compound is a promising lead for further development of cathepsin G inhibitors targeting chronic inflammatory disorders.
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Affiliation(s)
- Joakim E Swedberg
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - Choi Yi Li
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - Simon J de Veer
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - Conan K Wang
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
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21
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de Veer SJ, Swedberg JE, Brattsand M, Clements JA, Harris JM. Exploring the active site binding specificity of kallikrein-related peptidase 5 (KLK5) guides the design of new peptide substrates and inhibitors. Biol Chem 2016; 397:1237-1249. [DOI: 10.1515/hsz-2016-0112] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 02/16/2016] [Indexed: 12/24/2022]
Abstract
Abstract
Kallikrein-related peptidase 5 (KLK5) is a promising therapeutic target in several skin diseases, including Netherton syndrome, and is emerging as a potential target in various cancers. In this study, we used a sparse matrix library of 125 individually synthesized peptide substrates to characterize the binding specificity of KLK5. The sequences most favored by KLK5 were GRSR, YRSR and GRNR, and we identified sequence-specific interactions involving the peptide N-terminus by analyzing kinetic constants (kcat and KM) and performing molecular dynamics simulations. KLK5 inhibitors were subsequently engineered by substituting substrate sequences into the binding loop (P1, P2 and P4 residues) of sunflower trypsin inhibitor-1 (SFTI-1). These inhibitors were effective against KLK5 but showed limited selectivity, and performing a further substitution at P2′ led to the design of a new variant that displayed improved activity against KLK5 (Ki=4.2±0.2 nm), weak activity against KLK7 and 12-fold selectivity over KLK14. Collectively, these findings provide new insight into the design of highly favored binding sequences for KLK5 and reveal several opportunities for modulating inhibitor selectivity over closely related proteases that will be useful for future studies aiming to develop therapeutic molecules targeting KLK5.
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22
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Riley BT, Ilyichova O, Costa MGS, Porebski BT, de Veer SJ, Swedberg JE, Kass I, Harris JM, Hoke DE, Buckle AM. Direct and indirect mechanisms of KLK4 inhibition revealed by structure and dynamics. Sci Rep 2016; 6:35385. [PMID: 27767076 PMCID: PMC5073354 DOI: 10.1038/srep35385] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 09/28/2016] [Indexed: 11/09/2022] Open
Abstract
The kallikrein-related peptidase (KLK) family of proteases is involved in many aspects of human health and disease. One member of this family, KLK4, has been implicated in cancer development and metastasis. Understanding mechanisms of inactivation are critical to developing selective KLK4 inhibitors. We have determined the X-ray crystal structures of KLK4 in complex with both sunflower trypsin inhibitor-1 (SFTI-1) and a rationally designed SFTI-1 derivative to atomic (~1 Å) resolution, as well as with bound nickel. These structures offer a structural rationalization for the potency and selectivity of these inhibitors, and together with MD simulation and computational analysis, reveal a dynamic pathway between the metal binding exosite and the active site, providing key details of a previously proposed allosteric mode of inhibition. Collectively, this work provides insight into both direct and indirect mechanisms of inhibition for KLK4 that have broad implications for the enzymology of the serine protease superfamily, and may potentially be exploited for the design of therapeutic inhibitors.
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Affiliation(s)
- Blake T Riley
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Olga Ilyichova
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Mauricio G S Costa
- Programa de Computação Científica, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Benjamin T Porebski
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Simon J de Veer
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland 4059, Australia
| | - Joakim E Swedberg
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Itamar Kass
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Jonathan M Harris
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland 4059, Australia
| | - David E Hoke
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Ashley M Buckle
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
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23
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de Veer SJ, Furio L, Swedberg JE, Munro CA, Brattsand M, Clements JA, Hovnanian A, Harris JM. Selective Substrates and Inhibitors for Kallikrein-Related Peptidase 7 (KLK7) Shed Light on KLK Proteolytic Activity in the Stratum Corneum. J Invest Dermatol 2016; 137:430-439. [PMID: 27697464 DOI: 10.1016/j.jid.2016.09.017] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Revised: 09/05/2016] [Accepted: 09/16/2016] [Indexed: 01/01/2023]
Abstract
Proteases have pivotal roles in the skin's outermost layer, the epidermis. In the stratum corneum, serine proteases from the kallikrein-related peptidase (KLK) family have been implicated in several key homeostatic processes, including desquamation. However, the precise contribution of specific KLKs to each process remains unclear. To address this, we used a chemical biology approach and designed selective substrates and inhibitors for KLK7, the most abundant KLK protease in the stratum corneum. The resulting KLK7 inhibitor is the most potent inhibitor of this protease reported to date (Ki = 140 pM), and displays at least 1,000-fold selectivity over several proteases that are related by function (KLK5 and KLK14) or specificity (chymotrypsin). We then used substrates and inhibitors for KLK5, KLK7, and KLK14 to explore the activity of each protease in the stratum corneum using casein zymography and an ex vivo desquamation assay. These experiments provide the most detailed assessment of each KLK's contribution to corneocyte shedding in the plantar stratum corneum, revealing that inhibition of KLK7 alone is sufficient to block shedding, whereas KLK5 is also a major contributor. Collectively, these findings unveil chemical tools for studying KLK activity and demonstrate their potential for characterizing KLK biological functions in epidermal homeostasis.
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Affiliation(s)
- Simon J de Veer
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia; Laboratory of Genetic Skin Diseases, INSERM UMR 1163 and Imagine Institute of Genetic Diseases, Paris, France; Université Paris V Descartes-Sorbonne Paris Cité, Paris, France
| | - Laetitia Furio
- Laboratory of Genetic Skin Diseases, INSERM UMR 1163 and Imagine Institute of Genetic Diseases, Paris, France; Université Paris V Descartes-Sorbonne Paris Cité, Paris, France
| | - Joakim E Swedberg
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Christopher A Munro
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Maria Brattsand
- Department of Medical Biosciences, Pathology, Umeå University, Umeå, Sweden
| | - Judith A Clements
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia; Australian Prostate Cancer Research Centre, Translational Research Institute, Brisbane, Queensland, Australia
| | - Alain Hovnanian
- Laboratory of Genetic Skin Diseases, INSERM UMR 1163 and Imagine Institute of Genetic Diseases, Paris, France; Université Paris V Descartes-Sorbonne Paris Cité, Paris, France; Department of Genetics, Necker Hospital for Sick Children, Paris, France
| | - Jonathan M Harris
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia.
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24
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Swedberg JE, Mahatmanto T, Abdul Ghani H, de Veer SJ, Schroeder CI, Harris JM, Craik DJ. Substrate-Guided Design of Selective FXIIa Inhibitors Based on the Plant-Derived Momordica cochinchinensis Trypsin Inhibitor-II (MCoTI-II) Scaffold. J Med Chem 2016; 59:7287-92. [DOI: 10.1021/acs.jmedchem.6b00557] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joakim E. Swedberg
- Institute
for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Tunjung Mahatmanto
- Institute
for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Hafiza Abdul Ghani
- Institute
for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Simon J. de Veer
- Institute
of Health and Biomedical Innovation, Queensland University of Technology, Brisbane Queensland 4059, Australia
| | - Christina I. Schroeder
- Institute
for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jonathan M. Harris
- Institute
of Health and Biomedical Innovation, Queensland University of Technology, Brisbane Queensland 4059, Australia
| | - David J. Craik
- Institute
for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
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de Veer SJ, Ukolova SS, Munro CA, Swedberg JE, Buckle AM, Harris JM. Mechanism-based selection of a potent kallikrein-related peptidase 7 inhibitor from a versatile library based on the sunflower trypsin inhibitor SFTI-1. Biopolymers 2016; 100:510-8. [PMID: 24078181 DOI: 10.1002/bip.22231] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 03/01/2013] [Accepted: 03/02/2013] [Indexed: 02/06/2023]
Abstract
Potent and specific enzyme inhibition is a key goal in the development of therapeutic inhibitors targeting proteolytic activity. The backbone-cyclized peptide, Sunflower Trypsin Inhibitor (SFTI-1) affords a scaffold that can be engineered to achieve both these aims. SFTI-1's mechanism of inhibition is unusual in that it shows fast-on/slow-off kinetics driven by cleavage and religation of a scissile bond. This phenomenon was used to select a nanomolar inhibitor of kallikrein-related peptidase 7 (KLK7) from a versatile library of SFTI variants with diversity tailored to exploit distinctive surfaces present in the active site of serine proteases. Inhibitor selection was achieved through the use of size exclusion chromatography to separate protease/inhibitor complexes from unbound inhibitors followed by inhibitor identification according to molecular mass ascertained by mass spectrometry. This approach identified a single dominant inhibitor species with molecular weight of 1562.4 Da, which is consistent with the SFTI variant SFTI-WCTF. Once synthesized individually this inhibitor showed an IC50 of 173.9 ± 7.6 nM against chromogenic substrates and could block protein proteolysis. Molecular modeling analysis suggested that selection of SFTI-WCTF was driven by specific aromatic interactions and stabilized by an enhanced internal hydrogen bonding network. This approach provides a robust and rapid route to inhibitor selection and design.
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Affiliation(s)
- Simon J de Veer
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, 4059, Australia
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de Veer SJ, Wang CK, Harris JM, Craik DJ, Swedberg JE. Improving the Selectivity of Engineered Protease Inhibitors: Optimizing the P2 Prime Residue Using a Versatile Cyclic Peptide Library. J Med Chem 2015; 58:8257-68. [PMID: 26393374 DOI: 10.1021/acs.jmedchem.5b01148] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Standard mechanism inhibitors are attractive design templates for engineering reversible serine protease inhibitors. When optimizing interactions between the inhibitor and target protease, many studies focus on the nonprimed segment of the inhibitor's binding loop (encompassing the contact β-strand). However, there are currently few methods for screening residues on the primed segment. Here, we designed a synthetic inhibitor library (based on sunflower trypsin inhibitor-1) for characterizing the P2' specificity of various serine proteases. Screening the library against 13 different proteases revealed unique P2' preferences for trypsin, chymotrypsin, matriptase, plasmin, thrombin, four kallikrein-related peptidases, and several clotting factors. Using this information to modify existing engineered inhibitors yielded new variants that showed considerably improved selectivity, reaching up to 7000-fold selectivity over certain off-target proteases. Our study demonstrates the importance of the P2' residue in standard mechanism inhibition and unveils a new approach for screening P2' substitutions that will benefit future inhibitor engineering studies.
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Affiliation(s)
- Simon J de Veer
- Institute of Health and Biomedical Innovation, Queensland University of Technology , Brisbane, Queensland QLD 4059, Australia
| | - Conan K Wang
- Institute for Molecular Bioscience, The University of Queensland , 306 Carmody Road, Building 80, Queensland Bioscience Presinct, Brisbane, Queensland, QLD 4072, Australia
| | - Jonathan M Harris
- Institute of Health and Biomedical Innovation, Queensland University of Technology , Brisbane, Queensland QLD 4059, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland , 306 Carmody Road, Building 80, Queensland Bioscience Presinct, Brisbane, Queensland, QLD 4072, Australia
| | - Joakim E Swedberg
- Institute for Molecular Bioscience, The University of Queensland , 306 Carmody Road, Building 80, Queensland Bioscience Presinct, Brisbane, Queensland, QLD 4072, Australia
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de Veer SJ, Furio L, Harris JM, Hovnanian A. Proteases and proteomics: Cutting to the core of human skin pathologies. Proteomics Clin Appl 2014; 8:389-402. [DOI: 10.1002/prca.201300081] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 10/22/2013] [Accepted: 11/07/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Simon J. de Veer
- Université Paris Descartes - Sorbonne Paris Cité; Paris France
- INSERM UMR 1163, Laboratory of Genetic Skin Diseases, Imagine Institute; Paris France
- Institute of Health and Biomedical Innovation; Queensland University of Technology; Brisbane Australia
| | - Laetitia Furio
- Université Paris Descartes - Sorbonne Paris Cité; Paris France
- INSERM UMR 1163, Laboratory of Genetic Skin Diseases, Imagine Institute; Paris France
| | - Jonathan M. Harris
- Institute of Health and Biomedical Innovation; Queensland University of Technology; Brisbane Australia
| | - Alain Hovnanian
- Université Paris Descartes - Sorbonne Paris Cité; Paris France
- INSERM UMR 1163, Laboratory of Genetic Skin Diseases, Imagine Institute; Paris France
- Department of Genetics; Necker Hospital for Sick Children; Paris France
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de Veer SJ, Furio L, Harris JM, Hovnanian A. Proteases: common culprits in human skin disorders. Trends Mol Med 2014; 20:166-78. [DOI: 10.1016/j.molmed.2013.11.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 11/24/2013] [Accepted: 11/25/2013] [Indexed: 12/17/2022]
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de Veer SJ, Ukolova SS, Munro CA, Swedberg JE, Buckle AM, Harris JM. Mechanism-based selection of a potent kallikrein-related peptidase 7 inhibitor from a versatile library based on the sunflower trypsin inhibitor SFTI-1. Biopolymers 2013:n/a-n/a. [PMID: 23494567 DOI: 10.1002/peps.22231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 03/01/2013] [Accepted: 03/02/2013] [Indexed: 11/11/2022]
Abstract
Potent and specific enzyme inhibition is a key goal in development of therapeutic inhibitors targeting proteolytic activity. The backbone-cyclised peptide, Sunflower Trypsin Inhibitor (SFTI-1) affords a scaffold that can be engineered to achieve both these aims. SFTI-1's mechanism of inhibition is unusual in that it shows fast-on/slow-off kinetics driven by cleavage and religation of a scissile bond. This phenomenon was used to select a nanomolar inhibitor of kallikrein related peptidase 7 (KLK7) from a versatile library of SFTI variants with diversity tailored to exploit distinctive surfaces present in the active site of serine proteases. Inhibitor selection was achieved through use of size exclusion chromatography to separate protease/inhibitor complexes from unbound inhibitors followed by inhibitor identification according to molecular mass ascertained by mass spectrometry. This approach identified a single dominant inhibitor species with molecular weight of 1562.4 Da, which is consistent with the SFTI variant SFTI-WCTF. Once synthesised individually this inhibitor showed an IC50 of 173.9±7.6 nM against chromogenic substrates and could block protein proteolysis. Molecular modelling analysis suggested that selection of SFTI-WCTF was driven by specific aromatic interactions and stabilised by an enhanced internal hydrogen bonding network. This approach provides a robust and rapid route to inhibitor selection and design. © 2013 Wiley Periodicals, Inc. Biopolymers, 2013.
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Affiliation(s)
- Simon J de Veer
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, 4059, Australia
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de Veer SJ, Swedberg JE, Parker EA, Harris JM. Non-combinatorial library screening reveals subsite cooperativity and identifies new high-efficiency substrates for kallikrein-related peptidase 14. Biol Chem 2012; 393:331-41. [PMID: 22505516 DOI: 10.1515/bc-2011-250] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 12/05/2011] [Indexed: 11/15/2022]
Abstract
An array of substrates link the tryptic serine protease, kallikrein-related peptidase 14 (KLK14), to physiological functions including desquamation and activation of signaling molecules associated with inflammation and cancer. Recognition of protease cleavage sequences is driven by complementarity between exposed substrate motifs and the physicochemical signature of an enzyme's active site cleft. However, conventional substrate screening methods have generated conflicting subsite profiles for KLK14. This study utilizes a recently developed screening technique, the sparse matrix library, to identify five novel high-efficiency sequences for KLK14. The optimal sequence, YASR, was cleaved with higher efficiency (k(cat)/K(m)=3.81 ± 0.4 × 10(6) M(-1) s(-1)) than favored substrates from positional scanning and phage display by 2- and 10-fold, respectively. Binding site cooperativity was prominent among preferred sequences, which enabled optimal interaction at all subsites as indicated by predictive modeling of KLK14/substrate complexes. These simulations constitute the first molecular dynamics analysis of KLK14 and offer a structural rationale for the divergent subsite preferences evident between KLK14 and closely related KLKs, KLK4 and KLK5. Collectively, these findings highlight the importance of binding site cooperativity in protease substrate recognition, which has implications for discovery of optimal substrates and engineering highly effective protease inhibitors.
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Affiliation(s)
- Simon J de Veer
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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Sanchez WY, de Veer SJ, Swedberg JE, Hong EJ, Reid JC, Walsh TP, Hooper JD, Hammond GL, Clements JA, Harris JM. Selective cleavage of human sex hormone-binding globulin by kallikrein-related peptidases and effects on androgen action in LNCaP prostate cancer cells. Endocrinology 2012; 153:3179-89. [PMID: 22547569 DOI: 10.1210/en.2012-1011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Stimulation of the androgen receptor via bioavailable androgens, including testosterone and testosterone metabolites, is a key driver of prostate development and the early stages of prostate cancer. Androgens are hydrophobic and as such require carrier proteins, including sex hormone-binding globulin (SHBG), to enable efficient distribution from sites of biosynthesis to target tissues. The similarly hydrophobic corticosteroids also require a carrier protein whose affinity for steroid is modulated by proteolysis. However, proteolytic mechanisms regulating the SHBG/androgen complex have not been reported. Here, we show that the cancer-associated serine proteases, kallikrein-related peptidase (KLK)4 and KLK14, bind strongly to SHBG in glutathione S-transferase interaction analyses. Further, we demonstrate that active KLK4 and KLK14 cleave human SHBG at unique sites and in an androgen-dependent manner. KLK4 separated androgen-free SHBG into its two laminin G-like (LG) domains that were subsequently proteolytically stable even after prolonged digestion, whereas a catalytically equivalent amount of KLK14 reduced SHBG to small peptide fragments over the same period. Conversely, proteolysis of 5α-dihydrotestosterone (DHT)-bound SHBG was similar for both KLKs and left the steroid binding LG4 domain intact. Characterization of this proteolysis fragment by [(3)H]-labeled DHT binding assays revealed that it retained identical affinity for androgen compared with full-length SHBG (dissociation constant = 1.92 nM). Consistent with this, both full-length SHBG and SHBG-LG4 significantly increased DHT-mediated transcriptional activity of the androgen receptor compared with DHT delivered without carrier protein. Collectively, these data provide the first evidence that SHBG is a target for proteolysis and demonstrate that a stable fragment derived from proteolysis of steroid-bound SHBG retains binding function in vitro.
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Affiliation(s)
- Washington Y Sanchez
- Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland 4059, Australia
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Swedberg JE, de Veer SJ, Sit KC, Reboul CF, Buckle AM, Harris JM. Mastering the canonical loop of serine protease inhibitors: enhancing potency by optimising the internal hydrogen bond network. PLoS One 2011; 6:e19302. [PMID: 21556330 PMCID: PMC3083445 DOI: 10.1371/journal.pone.0019302] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 03/29/2011] [Indexed: 11/18/2022] Open
Abstract
Background Canonical serine protease inhibitors commonly bind to their targets through a rigid loop stabilised by an internal hydrogen bond network and disulfide bond(s). The smallest of these is sunflower trypsin inhibitor (SFTI-1), a potent and broad-range protease inhibitor. Recently, we re-engineered the contact β-sheet of SFTI-1 to produce a selective inhibitor of kallikrein-related peptidase 4 (KLK4), a protease associated with prostate cancer progression. However, modifications in the binding loop to achieve specificity may compromise structural rigidity and prevent re-engineered inhibitors from reaching optimal binding affinity. Methodology/Principal Findings In this study, the effect of amino acid substitutions on the internal hydrogen bonding network of SFTI were investigated using an in silico screen of inhibitor variants in complex with KLK4 or trypsin. Substitutions favouring internal hydrogen bond formation directly correlated with increased potency of inhibition in vitro. This produced a second generation inhibitor (SFTI-FCQR Asn14) which displayed both a 125-fold increased capacity to inhibit KLK4 (Ki = 0.0386±0.0060 nM) and enhanced selectivity over off-target serine proteases. Further, SFTI-FCQR Asn14 was stable in cell culture and bioavailable in mice when administered by intraperitoneal perfusion. Conclusion/Significance These findings highlight the importance of conserving structural rigidity of the binding loop in addition to optimising protease/inhibitor contacts when re-engineering canonical serine protease inhibitors.
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Affiliation(s)
- Joakim E. Swedberg
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Simon J. de Veer
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Kei C. Sit
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Cyril F. Reboul
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine and Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
| | - Ashley M. Buckle
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine and Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
| | - Jonathan M. Harris
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- * E-mail:
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Abstract
AbstractThe kallikreins and kallikrein-related peptidases are serine proteases that control a plethora of developmental and homeostatic phenomena, ranging from semen liquefaction to skin desquamation and blood pressure. The diversity of roles played by kallikreins has stimulated considerable interest in these enzymes from the perspective of diagnostics and drug design. Kallikreins already have well-established credentials as targets for therapeutic intervention and there is increasing appreciation of their potential both as biomarkers and as targets for inhibitor design. Here, we explore the current status of naturally occurring kallikrein protease-inhibitor complexes and illustrate how this knowledge can interface with strategies for rational re-engineering of bioscaffolds and design of small-molecule inhibitors.
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Swedberg JE, Nigon LV, Reid JC, de Veer SJ, Walpole CM, Stephens CR, Walsh TP, Takayama TK, Hooper JD, Clements JA, Buckle AM, Harris JM. Substrate-Guided Design of a Potent and Selective Kallikrein-Related Peptidase Inhibitor for Kallikrein 4. ACTA ACUST UNITED AC 2009; 16:633-43. [DOI: 10.1016/j.chembiol.2009.05.008] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Revised: 04/30/2009] [Accepted: 05/08/2009] [Indexed: 12/31/2022]
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