1
|
Palpal-Latoc D, Horsfall AJ, Cameron AJ, Campbell G, Ferguson SA, Cook GM, Sander V, Davidson AJ, Harris PWR, Brimble MA. Synthesis, Structure-Activity Relationship Study, Bioactivity, and Nephrotoxicity Evaluation of the Proposed Structure of the Cyclic Lipodepsipeptide Brevicidine B. J Nat Prod 2024. [PMID: 38423998 DOI: 10.1021/acs.jnatprod.3c00876] [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] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
The brevicidines represent a novel class of nonribosomal antimicrobial peptides that possess remarkable potency and selectivity toward highly problematic and resistant Gram-negative pathogenic bacteria. A recently discovered member of the brevicidine family, coined brevicidine B (2), comprises a single amino acid substitution (from d-Tyr2 to d-Phe2) in the amino acid sequence of the linear moiety of brevicidine (1) and was reported to exhibit broader antimicrobial activity against both Gram-negative (MIC = 2-4 μgmL-1) and Gram-positive (MIC = 2-8 μgmL-1) pathogens. Encouraged by this, we herein report the first total synthesis of the proposed structure of brevicidine B (2), building on our previously reported synthetic strategy to access brevicidine (1). In agreement with the original isolation paper, pleasingly, synthetic 2 demonstrated antimicrobial activity toward Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae (MIC = 4-8 μgmL-1). Interestingly, however, synthetic 2 was inactive toward all of the tested Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus strains. Substitution of d-Phe2 with its enantiomer, and other hydrophobic residues, yields analogues that were either inactive or only exhibited activity toward Gram-negative strains. The striking difference in the biological activity of our synthetic 2 compared to the reported natural compound warrants the re-evaluation of the original natural product for purity or possible differences in relative configuration. Finally, the evaluation of synthetic 1 and 2 in a human kidney organoid model of nephrotoxicity revealed substantial toxicity of both compounds, although 1 was less toxic than 2 and polymyxin B. These results indicate that modification to position 2 may afford a strategy to mitigate the nephrotoxicity of brevicidine.
Collapse
Affiliation(s)
- Dennise Palpal-Latoc
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, 3 Symonds Street, Auckland 1010, New Zealand
- School of Biological Sciences, The University of Auckland, 3A Symonds Street, Auckland 1010, New Zealand
| | - Aimee J Horsfall
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, 3 Symonds Street, Auckland 1010, New Zealand
- School of Biological Sciences, The University of Auckland, 3A Symonds Street, Auckland 1010, New Zealand
| | - Alan J Cameron
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, 3 Symonds Street, Auckland 1010, New Zealand
- School of Biological Sciences, The University of Auckland, 3A Symonds Street, Auckland 1010, New Zealand
| | - Georgia Campbell
- Department of Microbiology and Immunology, School of Medical Sciences, The University of Otago, 720 Cumberland Street, Dunedin 9054, New Zealand
| | - Scott A Ferguson
- Department of Microbiology and Immunology, School of Medical Sciences, The University of Otago, 720 Cumberland Street, Dunedin 9054, New Zealand
| | - Gregory M Cook
- Department of Microbiology and Immunology, School of Medical Sciences, The University of Otago, 720 Cumberland Street, Dunedin 9054, New Zealand
| | - Veronika Sander
- Faculty of Medical and Health Sciences, The University of Auckland 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Alan J Davidson
- Faculty of Medical and Health Sciences, The University of Auckland 85 Park Road, Grafton, Auckland 1023, New Zealand
| | - Paul W R Harris
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, 3 Symonds Street, Auckland 1010, New Zealand
- School of Biological Sciences, The University of Auckland, 3A Symonds Street, Auckland 1010, New Zealand
| | - Margaret A Brimble
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, 3 Symonds Street, Auckland 1010, New Zealand
- School of Biological Sciences, The University of Auckland, 3A Symonds Street, Auckland 1010, New Zealand
| |
Collapse
|
2
|
Vandborg BC, Horsfall AJ, Pederick JL, Abell AD, Bruning JB. Towards a High-Affinity Peptidomimetic Targeting Proliferating Cell Nuclear Antigen from Aspergillus fumigatus. J Fungi (Basel) 2023; 9:1098. [PMID: 37998903 PMCID: PMC10672205 DOI: 10.3390/jof9111098] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/04/2023] [Accepted: 11/07/2023] [Indexed: 11/25/2023] Open
Abstract
Invasive fungal infections (IFIs) are prevalent in immunocompromised patients. Due to alarming levels of increasing resistance in clinical settings, new drugs targeting the major fungal pathogen Aspergillus fumigatus are required. Attractive drug targets are those involved in essential processes like DNA replication, such as proliferating cell nuclear antigens (PCNAs). PCNA has been previously studied in cancer research and presents a viable target for antifungals. Human PCNA interacts with the p21 protein, outcompeting binding proteins to halt DNA replication. The affinity of p21 for hPCNA has been shown to outcompete other associating proteins, presenting an attractive scaffold for peptidomimetic design. p21 has no A. fumigatus homolog to our knowledge, yet our group has previously demonstrated that human p21 can interact with A. fumigatus PCNA (afumPCNA). This suggests that a p21-based inhibitor could be designed to outcompete the native binding partners of afumPCNA to inhibit fungal growth. Here, we present an investigation of extensive structure-activity relationships between designed p21-based peptides and afumPCNA and the first crystal structure of a p21 peptide bound to afumPCNA, demonstrating that the A. fumigatus replication model uses a PIP-box sequence as the method for binding to afumPCNA. These results inform the new optimized secondary structure design of a potential peptidomimetic inhibitor of afumPCNA.
Collapse
Affiliation(s)
- Bethiney C. Vandborg
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide 5005, Australia; (B.C.V.); (J.L.P.); (A.D.A.)
- School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia
| | - Aimee J. Horsfall
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide 5005, Australia; (B.C.V.); (J.L.P.); (A.D.A.)
- ARC Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide, Adelaide 5005, Australia
| | - Jordan L. Pederick
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide 5005, Australia; (B.C.V.); (J.L.P.); (A.D.A.)
- School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia
| | - Andrew D. Abell
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide 5005, Australia; (B.C.V.); (J.L.P.); (A.D.A.)
- ARC Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide, Adelaide 5005, Australia
| | - John B. Bruning
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide 5005, Australia; (B.C.V.); (J.L.P.); (A.D.A.)
- School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia
| |
Collapse
|
3
|
Horsfall AJ, Chav T, Pederick JL, Kikhtyak Z, Vandborg BC, Kowalczyk W, Scanlon DB, Tilley WD, Hickey TE, Abell AD, Bruning JB. Designing Fluorescent Nuclear Permeable Peptidomimetics to Target Proliferating Cell Nuclear Antigen. J Med Chem 2023; 66:10354-10363. [PMID: 37489955 DOI: 10.1021/acs.jmedchem.3c00471] [Citation(s) in RCA: 0] [Impact Index Per Article: 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] [Indexed: 07/26/2023]
Abstract
Human proliferating cell nuclear antigen (PCNA) is a critical mediator of DNA replication and repair, acting as a docking platform for replication proteins. Disrupting these interactions with a peptidomimetic agent presents as a promising avenue to limit proliferation of cancerous cells. Here, a p21-derived peptide was employed as a starting scaffold to design a modular peptidomimetic that interacts with PCNA and is cellular and nuclear permeable. Ultimately, a peptidomimetic was produced which met these criteria, consisting of a fluorescein tag and SV40 nuclear localization signal conjugated to the N-terminus of a p21 macrocycle derivative. Attachment of the fluorescein tag was found to directly affect cellular uptake of the peptidomimetic, with fluorescein being requisite for nuclear permeability. This work provides an important step forward in the development of PCNA targeting peptidomimetics for use as anti-cancer agents or as cancer diagnostics.
Collapse
Affiliation(s)
- Aimee J Horsfall
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia
- School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics (CNBP), Adelaide, South Australia 5005, Australia
| | - Theresa Chav
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia
- School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics (CNBP), Adelaide, South Australia 5005, Australia
| | - Jordan L Pederick
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Zoya Kikhtyak
- Dame Roma Mitchell Cancer Research Laboratories, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Bethiney C Vandborg
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | | | - Denis B Scanlon
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia
- School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Wayne D Tilley
- Dame Roma Mitchell Cancer Research Laboratories, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Theresa E Hickey
- Dame Roma Mitchell Cancer Research Laboratories, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Andrew D Abell
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia
- School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics (CNBP), Adelaide, South Australia 5005, Australia
| | - John B Bruning
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| |
Collapse
|
4
|
Frkic RL, Pederick JL, Horsfall AJ, Jovcevski B, Crame EE, Kowalczyk W, Pukala TL, Chang MR, Zheng J, Blayo AL, Abell AD, Kamenecka TM, Harbort JS, Harmer JR, Griffin PR, Bruning JB. PPARγ Corepression Involves Alternate Ligand Conformation and Inflation of H12 Ensembles. ACS Chem Biol 2023; 18:1115-1123. [PMID: 37146157 DOI: 10.1021/acschembio.2c00917] [Citation(s) in RCA: 0] [Impact Index Per Article: 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] [Indexed: 05/07/2023]
Abstract
Inverse agonists of peroxisome proliferator activated receptor γ (PPARγ) have emerged as safer alternatives to full agonists for their reduced side effects while still maintaining impressive insulin-sensitizing properties. To shed light on their molecular mechanism, we characterized the interaction of the PPARγ ligand binding domain with SR10221. X-ray crystallography revealed a novel binding mode of SR10221 in the presence of a transcriptionally repressing corepressor peptide, resulting in much greater destabilization of the activation helix, H12, than without corepressor peptide. Electron paramagnetic resonance provided in-solution complementary protein dynamic data, which revealed that for SR10221-bound PPARγ, H12 adopts a plethora of conformations in the presence of corepressor peptide. Together, this provides the first direct evidence for corepressor-driven ligand conformation for PPARγ and will allow the development of safer and more effective insulin sensitizers suitable for clinical use.
Collapse
Affiliation(s)
- Rebecca L Frkic
- The Institute for Photonics and Advanced Sensing and School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Jordan L Pederick
- The Institute for Photonics and Advanced Sensing and School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Aimee J Horsfall
- ARC Centre of Excellence for Nanoscale Biophotonics, The Institute for Photonics and Advanced Sensing, and School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Blagojce Jovcevski
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Elise E Crame
- Discipline of Physiology, School of Biomedicine, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | | | - Tara L Pukala
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Mi Ra Chang
- Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458, United States
- Department of Molecular Therapeutics, UF Scripps Biomolecular Research, University of Florida, Jupiter, Florida 33458, United States
| | - Jie Zheng
- Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458, United States
- Department of Molecular Therapeutics, UF Scripps Biomolecular Research, University of Florida, Jupiter, Florida 33458, United States
| | - Anne-Laure Blayo
- Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458, United States
- Department of Molecular Therapeutics, UF Scripps Biomolecular Research, University of Florida, Jupiter, Florida 33458, United States
| | - Andrew D Abell
- ARC Centre of Excellence for Nanoscale Biophotonics, The Institute for Photonics and Advanced Sensing, and School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Theodore M Kamenecka
- Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458, United States
- Department of Molecular Therapeutics, UF Scripps Biomolecular Research, University of Florida, Jupiter, Florida 33458, United States
| | - Joshua S Harbort
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Patrick R Griffin
- Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458, United States
- Department of Molecular Therapeutics, UF Scripps Biomolecular Research, University of Florida, Jupiter, Florida 33458, United States
| | - John B Bruning
- The Institute for Photonics and Advanced Sensing and School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| |
Collapse
|
5
|
Palpal-Latoc D, Brimble MA, Harris PWR, Horsfall AJ. Factors influencing on-resin depsipeptide bond formation: case studies on daptomycin- and brevicidine-derived sequences. Org Biomol Chem 2023; 21:4052-4060. [PMID: 36988402 DOI: 10.1039/d3ob00360d] [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: 03/30/2023]
Abstract
Depsipeptides are an important class of bioactive natural products, where a growing number of genome-mined structures that display anti-microbial activity are macrocyclic depsipeptides. Chemically, peptide ester (depsipeptide) bond formation often displays low yields, and thereby hampers efforts to access these structures for structure-activity studies. Herein, we present a systematic study of the variables that influence depsipeptide bond formation on-resin, using simplified sequences derived from antibiotic peptides, daptomycin and brevicidine, prepared via Fmoc-based solid-phase synthesis. Our study highlights reaction solvent as the key determinant, where switching the solvent from DMF to DCM in almost all cases increased the amount of depsipeptide product. Limiting the number of amino-acids N-terminal to the reactive alcohol was also noted to significantly improve the acylation efficiency. The impact of different N-terminal and side-chain protecting groups, as well as stereochemistry, was also investigated. Additives to the reaction, such as inclusion of surfactants for esterification of long hydrophobic sequences, did not improve conversion. 6-ClHOBt, often added to improve acylation efficiency, notably decreased the amount of depsipeptide observed. Lastly, no significant difference between polystyrene and Tentagel® (PEG-decorated) resins were found for these sequences.
Collapse
Affiliation(s)
- Dennise Palpal-Latoc
- School of Chemical Science, School of Biological Sciences, Maurice Wilkins Centre for Biodiscovery, The University of Auckland, Auckland, 1021, New Zealand.
| | - Margaret A Brimble
- School of Chemical Science, School of Biological Sciences, Maurice Wilkins Centre for Biodiscovery, The University of Auckland, Auckland, 1021, New Zealand.
| | - Paul W R Harris
- School of Chemical Science, School of Biological Sciences, Maurice Wilkins Centre for Biodiscovery, The University of Auckland, Auckland, 1021, New Zealand.
| | - Aimee J Horsfall
- School of Chemical Science, School of Biological Sciences, Maurice Wilkins Centre for Biodiscovery, The University of Auckland, Auckland, 1021, New Zealand.
| |
Collapse
|
6
|
Pederick JL, Horsfall AJ, Jovcevski B, Klose J, Abell AD, Pukala TL, Bruning JB. Discovery of an ʟ-amino acid ligase implicated in Staphylococcal sulfur amino acid metabolism. J Biol Chem 2022; 298:102392. [PMID: 35988643 PMCID: PMC9486568 DOI: 10.1016/j.jbc.2022.102392] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/10/2022] [Accepted: 08/15/2022] [Indexed: 11/06/2022] Open
Abstract
Enzymes involved in Staphylococcus aureus amino acid metabolism have recently gained traction as promising targets for the development of new antibiotics, however, not all aspects of this process are understood. The ATP-grasp superfamily includes enzymes that predominantly catalyze the ATP-dependent ligation of various carboxylate and amine substrates. One subset, ʟ-amino acid ligases (LALs), primarily catalyze the formation of dipeptide products in Gram-positive bacteria, however, their involvement in S. aureus amino acid metabolism has not been investigated. Here, we present the characterization of the putative ATP-grasp enzyme (SAOUHSC_02373) from S. aureus NCTC 8325 and its identification as a novel LAL. First, we interrogated the activity of SAOUHSC_02373 against a panel of ʟ-amino acid substrates. As a result, we identified SAOUHSC_02373 as an LAL with high selectivity for ʟ-aspartate and ʟ-methionine substrates, specifically forming an ʟ-aspartyl–ʟ-methionine dipeptide. Thus, we propose that SAOUHSC_02373 be assigned as ʟ-aspartate–ʟ-methionine ligase (LdmS). To further understand this unique activity, we investigated the mechanism of LdmS by X-ray crystallography, molecular modeling, and site-directed mutagenesis. Our results suggest that LdmS shares a similar mechanism to other ATP-grasp enzymes but possesses a distinctive active site architecture that confers selectivity for the ʟ-Asp and ʟ-Met substrates. Phylogenetic analysis revealed LdmS homologs are highly conserved in Staphylococcus and closely related Gram-positive Firmicutes. Subsequent genetic analysis upstream of the ldmS operon revealed several trans-acting regulatory elements associated with control of Met and Cys metabolism. Together, these findings support a role for LdmS in Staphylococcal sulfur amino acid metabolism.
Collapse
Affiliation(s)
- Jordan L Pederick
- Institute for Photonics and Advanced Sensing, (IPAS), School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Aimee J Horsfall
- Institute for Photonics and Advanced Sensing, (IPAS), School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia; ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Adelaide, South Australia 5005, Australia
| | - Blagojce Jovcevski
- Department of Chemistry, The University of Adelaide, Adelaide, South Australia 5005, Australia; School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Jack Klose
- Department of Chemistry, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Andrew D Abell
- Institute for Photonics and Advanced Sensing, (IPAS), School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia; ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Adelaide, South Australia 5005, Australia
| | - Tara L Pukala
- Department of Chemistry, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - John B Bruning
- Institute for Photonics and Advanced Sensing, (IPAS), School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
| |
Collapse
|
7
|
Horsfall AJ, Vandborg BA, Kikhtyak Z, Scanlon DB, Tilley WD, Hickey TE, Bruning JB, Abell AD. A cell permeable bimane-constrained PCNA-interacting peptide. RSC Chem Biol 2021; 2:1499-1508. [PMID: 34704055 PMCID: PMC8496261 DOI: 10.1039/d1cb00113b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 05/19/2021] [Accepted: 07/19/2021] [Indexed: 11/21/2022] Open
Abstract
The human sliding clamp protein known as proliferating cell nuclear antigen (PCNA) orchestrates DNA-replication and -repair and as such is an ideal therapeutic target for proliferative diseases, including cancer. Peptides derived from the human p21 protein bind PCNA with high affinity via a 310-helical binding conformation and are known to shut down DNA-replication. Here, we present studies on short analogues of p21 peptides (143-151) conformationally constrained with a covalent linker between i, i + 4 separated cysteine residues at positions 145 and 149 to access peptidomimetics that target PCNA. The resulting macrocycles bind PCNA with K D values ranging from 570 nM to 3.86 μM, with the bimane-constrained peptide 7 proving the most potent. Subsequent X-ray crystallography and computational modelling studies of the macrocyclic peptides bound to PCNA indicated only the high-affinity peptide 7 adopted the classical 310-helical binding conformation. This suggests the 310-helical conformation is critical to high affinity PCNA binding, however NMR secondary shift analysis of peptide 7 revealed this secondary structure was not well-defined in solution. Peptide 7 is cell permeable and localised to the cell cytosol of breast cancer cells (MDA-MB-468), revealed by confocal microscopy showing blue fluorescence of the bimane linker. The inherent fluorescence of the bimane moiety present in peptide 7 allowed it to be directly imaged in the cell uptake assay, without attachment of an auxiliary fluorescent tag. This highlights a significant benefit of using a bimane constraint to access conformationally constrained macrocyclic peptides. This study identifies a small peptidomimetic that binds PCNA with higher affinity than previous reported p21 macrocycles, and is cell permeable, providing a significant advance toward development of a PCNA inhibitor for therapeutic applications.
Collapse
Affiliation(s)
- Aimee J Horsfall
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide Adelaide South Australia 5005 Australia .,School of Physical Sciences, The University of Adelaide Adelaide South Australia 5005 Australia.,Australian Research Council Centre of Excellence for Nanoscale BioPhotonics (CNBP) Australia
| | - Beth A Vandborg
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide Adelaide South Australia 5005 Australia .,School of Biological Sciences, The University of Adelaide Adelaide South Australia 5005 Australia
| | - Zoya Kikhtyak
- Dame Roma Mitchell Cancer Research Laboratories, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide Adelaide South Australia 5005 Australia
| | - Denis B Scanlon
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide Adelaide South Australia 5005 Australia .,School of Physical Sciences, The University of Adelaide Adelaide South Australia 5005 Australia
| | - Wayne D Tilley
- Dame Roma Mitchell Cancer Research Laboratories, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide Adelaide South Australia 5005 Australia
| | - Theresa E Hickey
- Dame Roma Mitchell Cancer Research Laboratories, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide Adelaide South Australia 5005 Australia
| | - John B Bruning
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide Adelaide South Australia 5005 Australia .,School of Biological Sciences, The University of Adelaide Adelaide South Australia 5005 Australia
| | - Andrew D Abell
- Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide Adelaide South Australia 5005 Australia .,School of Physical Sciences, The University of Adelaide Adelaide South Australia 5005 Australia.,Australian Research Council Centre of Excellence for Nanoscale BioPhotonics (CNBP) Australia
| |
Collapse
|
8
|
Horsfall AJ, McDougal DP, Scanlon DB, Bruning JB, Abell AD. Approaches to Introduce Helical Structure in Cysteine-Containing Peptides with a Bimane Group. Chembiochem 2021; 22:2711-2720. [PMID: 34107164 DOI: 10.1002/cbic.202100241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/08/2021] [Indexed: 01/01/2023]
Abstract
An i-i+4 or i-i+3 bimane-containing linker was introduced into a peptide known to target Estrogen Receptor alpha (ERα), in order to stabilise an α-helical geometry. These macrocycles were studied by CD and NMR to reveal the i-i+4 constrained peptide adopts a 310 -helical structure in solution, and an α-helical conformation on interaction with the ERα coactivator recruitment surface in silico. An acyclic bimane-modified peptide is also helical, when it includes a tryptophan or tyrosine residue; but is significantly less helical with a phenylalanine or alanine residue, which indicates such a bimane modification influences peptide structure in a sequence dependent manner. The fluorescence intensity of the bimane appears influenced by peptide conformation, where helical peptides displayed a fluorescence increase when TFE was added to phosphate buffer, compared to a decrease for less helical peptides. This study presents the bimane as a useful modification to influence peptide structure as an acyclic peptide modification, or as a side-chain constraint to give a macrocycle.
Collapse
Affiliation(s)
- Aimee J Horsfall
- ARC Centre of Excellence for Nanoscale Biophotonics (CNBP), University of Adelaide, Adelaide, SA 5005, Australia.,Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia.,The Institute for Photonics & Advanced Sensing (IPAS), University of Adelaide, Adelaide, SA 5005, Australia
| | - Daniel P McDougal
- The Institute for Photonics & Advanced Sensing (IPAS), University of Adelaide, Adelaide, SA 5005, Australia.,School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Denis B Scanlon
- Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia.,The Institute for Photonics & Advanced Sensing (IPAS), University of Adelaide, Adelaide, SA 5005, Australia
| | - John B Bruning
- The Institute for Photonics & Advanced Sensing (IPAS), University of Adelaide, Adelaide, SA 5005, Australia.,School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Andrew D Abell
- ARC Centre of Excellence for Nanoscale Biophotonics (CNBP), University of Adelaide, Adelaide, SA 5005, Australia.,Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia.,The Institute for Photonics & Advanced Sensing (IPAS), University of Adelaide, Adelaide, SA 5005, Australia
| |
Collapse
|
9
|
Horsfall AJ, Vandborg BA, Kowalczyk W, Chav T, Scanlon DB, Abell AD, Bruning JB. Unlocking the PIP-box: A peptide library reveals interactions that drive high-affinity binding to human PCNA. J Biol Chem 2021; 296:100773. [PMID: 33984330 PMCID: PMC8191301 DOI: 10.1016/j.jbc.2021.100773] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [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: 02/10/2021] [Revised: 05/02/2021] [Accepted: 05/09/2021] [Indexed: 12/26/2022] Open
Abstract
The human sliding clamp, Proliferating Cell Nuclear Antigen (hPCNA), interacts with over 200 proteins through a conserved binding motif, the PIP-box, to orchestrate DNA replication and repair. It is not clear how changes to the features of a PIP-box modulate protein binding and thus how they fine-tune downstream processes. Here, we present a systematic study of each position within the PIP-box to reveal how hPCNA-interacting peptides bind with drastically varied affinities. We synthesized a series of 27 peptides derived from the native protein p21 with small PIP-box modifications and another series of 19 peptides containing PIP-box binding motifs from other proteins. The hPCNA-binding affinity of all peptides, characterized as KD values determined by surface plasmon resonance, spanned a 4000-fold range, from 1.83 nM to 7.59 μM. The hPCNA-bound peptide structures determined by X-ray crystallography and modeled computationally revealed intermolecular and intramolecular interaction networks that correlate with high hPCNA affinity. These data informed rational design of three new PIP-box sequences, testing of which revealed the highest affinity hPCNA-binding partner to date, with a KD value of 1.12 nM, from a peptide with PIP-box QTRITEYF. This work showcases the sequence-specific nuances within the PIP-box that are responsible for high-affinity hPCNA binding, which underpins our understanding of how nature tunes hPCNA affinity to regulate DNA replication and repair processes. In addition, these insights will be useful to future design of hPCNA inhibitors.
Collapse
Affiliation(s)
- Aimee J Horsfall
- ARC Centre of Excellence for Nanoscale BioPhotonics, Institute of Photonics and Advanced Sensing, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Beth A Vandborg
- Institute of Photonics and Advanced Sensing, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | | | - Theresa Chav
- ARC Centre of Excellence for Nanoscale BioPhotonics, Institute of Photonics and Advanced Sensing, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Denis B Scanlon
- ARC Centre of Excellence for Nanoscale BioPhotonics, Institute of Photonics and Advanced Sensing, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Andrew D Abell
- ARC Centre of Excellence for Nanoscale BioPhotonics, Institute of Photonics and Advanced Sensing, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia, Australia.
| | - John B Bruning
- Institute of Photonics and Advanced Sensing, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia.
| |
Collapse
|
10
|
Horsfall AJ, Chav T, Bruning JB, Abell AD. A turn-on fluorescent PCNA sensor. Bioorg Med Chem Lett 2021; 41:128031. [PMID: 33839250 DOI: 10.1016/j.bmcl.2021.128031] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/31/2021] [Accepted: 04/05/2021] [Indexed: 10/21/2022]
Abstract
The solvatochromic amino-acids 4-DMNA or 4-DAPA, were separately introduced at position 147, 150 or 151 of a short p21 peptide (141-155) known to bind sliding clamp protein PCNA. The ability of these peptides, 1a-3a and 1b-3b, to act as a turn-on fluorescent sensor for PCNA was then investigated. The 4-DMNA-containing peptides (1a-3a) displayed up to a 40-fold difference in fluorescence between a polar (Tris buffer) and a hydrophobic solvent (dioxane with 5 mM 18-crown-6), while the 4-DAPA-containing peptides (1b-3b) displayed a significantly enhanced (300-fold) increase in fluorescence from Tris buffer to dioxane with 18-crown-6. SPR analysis of the peptides against PCNA revealed that the 151-substituted peptides 3a and 3b interacted specifically with PCNA, with KD values of 921 nM and 1.28 μM, respectively. Analysis of the fluorescence of these peptides in the presence of increasing concentrations of PCNA revealed a 10-fold change in fluorescence for 3a at 2.5 equivalents of PCNA, compared to only a 3.5-fold change in fluorescence for 3b. Peptide 3a is an important lead for development of a PCNA-selective turn-on fluorescent sensor for application as a cell proliferation sensor to investigate diseases such as cancer.
Collapse
Affiliation(s)
- Aimee J Horsfall
- ARC Centre of Excellence for Nanoscale BioPhotonics, Institute of Photonics and Advanced Sensing, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Theresa Chav
- ARC Centre of Excellence for Nanoscale BioPhotonics, Institute of Photonics and Advanced Sensing, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - John B Bruning
- Institute of Photonics and Advanced Sensing, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Andrew D Abell
- ARC Centre of Excellence for Nanoscale BioPhotonics, Institute of Photonics and Advanced Sensing, School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
| |
Collapse
|
11
|
Capon PK, Horsfall AJ, Li J, Schartner EP, Khalid A, Purdey MS, McLaughlin RA, Abell AD. Protein detection enabled using functionalised silk-binding peptides on a silk-coated optical fibre. RSC Adv 2021; 11:22334-22342. [PMID: 35480827 PMCID: PMC9034238 DOI: 10.1039/d1ra03584c] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 06/04/2021] [Indexed: 11/21/2022] Open
Abstract
We report a new approach to functionalise optical fibres to enable protein sensing, which controls the sensor molecule location either within the fibre tip coating or isolated to its exterior. This control dictates suitability for protein sensing.
Collapse
Affiliation(s)
- Patrick K. Capon
- School of Physical Sciences
- The University of Adelaide
- Adelaide
- Australia
- Institute for Photonics and Advanced Sensing
| | - Aimee J. Horsfall
- School of Physical Sciences
- The University of Adelaide
- Adelaide
- Australia
- Institute for Photonics and Advanced Sensing
| | - Jiawen Li
- Institute for Photonics and Advanced Sensing
- The University of Adelaide
- Adelaide
- Australia
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics
| | - Erik P. Schartner
- School of Physical Sciences
- The University of Adelaide
- Adelaide
- Australia
- Institute for Photonics and Advanced Sensing
| | - Asma Khalid
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics
- Australia
- Department of Physics
- School of Science
- RMIT University
| | - Malcolm S. Purdey
- School of Physical Sciences
- The University of Adelaide
- Adelaide
- Australia
- Institute for Photonics and Advanced Sensing
| | - Robert A. McLaughlin
- Institute for Photonics and Advanced Sensing
- The University of Adelaide
- Adelaide
- Australia
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics
| | - Andrew D. Abell
- School of Physical Sciences
- The University of Adelaide
- Adelaide
- Australia
- Institute for Photonics and Advanced Sensing
| |
Collapse
|
12
|
Horsfall AJ, Abell AD. An Inherently Fluorescent Peptide Constraint to Define Secondary Structure: Moving Away from Auxiliary Tags. Aust J Chem 2021. [DOI: 10.1071/ch21169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
13
|
Horsfall AJ, Dunning KR, Keeling KL, Scanlon DB, Wegener KL, Abell AD. A Bimane‐Based Peptide Staple for Combined Helical Induction and Fluorescent Imaging. Chembiochem 2020; 21:3423-3432. [DOI: 10.1002/cbic.202000485] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Aimee J. Horsfall
- The Department of Chemistry, School of Physical Sciences The University of Adelaide North Terrace Adelaide SA 5005 Australia
- The ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) The University of Adelaide North Terrace Adelaide SA 5005 Australia
- Institute for Photonics and Advanced Sensing (IPAS) The University of Adelaide North Terrace Adelaide SA 5005 Australia
| | - Kylie R. Dunning
- The ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) The University of Adelaide North Terrace Adelaide SA 5005 Australia
- Institute for Photonics and Advanced Sensing (IPAS) The University of Adelaide North Terrace Adelaide SA 5005 Australia
- Robinson Research Institute, Adelaide Medical School The University of Adelaide North Terrace Adelaide SA 5005 Australia
| | - Kelly L. Keeling
- The Department of Chemistry, School of Physical Sciences The University of Adelaide North Terrace Adelaide SA 5005 Australia
- Institute for Photonics and Advanced Sensing (IPAS) The University of Adelaide North Terrace Adelaide SA 5005 Australia
| | - Denis B. Scanlon
- The Department of Chemistry, School of Physical Sciences The University of Adelaide North Terrace Adelaide SA 5005 Australia
- Institute for Photonics and Advanced Sensing (IPAS) The University of Adelaide North Terrace Adelaide SA 5005 Australia
| | - Kate L. Wegener
- Institute for Photonics and Advanced Sensing (IPAS) The University of Adelaide North Terrace Adelaide SA 5005 Australia
- School of Biological Sciences The University of Adelaide North Terrace Adelaide SA 5005 Australia
| | - Andrew D. Abell
- The Department of Chemistry, School of Physical Sciences The University of Adelaide North Terrace Adelaide SA 5005 Australia
- The ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) The University of Adelaide North Terrace Adelaide SA 5005 Australia
- Institute for Photonics and Advanced Sensing (IPAS) The University of Adelaide North Terrace Adelaide SA 5005 Australia
| |
Collapse
|
14
|
Affiliation(s)
- Aimee J. Horsfall
- ARC Centre of Excellence for Nanoscale BioPhotonicsInstitute for Photonics and Advanced Sensing (IPAS)Department of ChemistryUniversity of Adelaide Nth Tce Adelaide 5005 Australia
| | - Andrew D. Abell
- ARC Centre of Excellence for Nanoscale BioPhotonicsInstitute for Photonics and Advanced Sensing (IPAS)Department of ChemistryUniversity of Adelaide Nth Tce Adelaide 5005 Australia
| | - John B. Bruning
- Institute of Photonics and Advanced Sensing (IPAS)School of Biological SciencesUniversity of Adelaide Nth Tce Adelaide 5005 Australia
| |
Collapse
|