1
|
Hogan AM, Motnenko A, Rahman ASMZ, Cardona ST. Cell envelope structural and functional contributions to antibiotic resistance in Burkholderia cenocepacia. J Bacteriol 2024; 206:e0044123. [PMID: 38501654 PMCID: PMC11025338 DOI: 10.1128/jb.00441-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 03/05/2024] [Indexed: 03/20/2024] Open
Abstract
Antibiotic activity is limited by the physical construction of the Gram-negative cell envelope. Species of the Burkholderia cepacia complex (Bcc) are known as intrinsically multidrug-resistant opportunistic pathogens with low permeability cell envelopes. Here, we re-examined a previously performed chemical-genetic screen of barcoded transposon mutants in B. cenocepacia K56-2, focusing on cell envelope structural and functional processes. We identified structures mechanistically important for resistance to singular and multiple antibiotic classes. For example, susceptibility to novobiocin, avibactam, and the LpxC inhibitor, PF-04753299, was linked to the BpeAB-OprB efflux pump, suggesting these drugs are substrates for this pump in B. cenocepacia. Defects in peptidoglycan precursor synthesis specifically increased susceptibility to cycloserine and revealed a new putative amino acid racemase, while defects in divisome accessory proteins increased susceptibility to multiple β-lactams. Additionally, disruption of the periplasmic disulfide bond formation system caused pleiotropic defects on outer membrane integrity and β-lactamase activity. Our findings highlight the layering of resistance mechanisms in the structure and function of the cell envelope. Consequently, we point out processes that can be targeted for developing antibiotic potentiators.IMPORTANCEThe Gram-negative cell envelope is a double-layered physical barrier that protects cells from extracellular stressors, such as antibiotics. The Burkholderia cell envelope is known to contain additional modifications that reduce permeability. We investigated Burkholderia cell envelope factors contributing to antibiotic resistance from a genome-wide view by re-examining data from a transposon mutant library exposed to an antibiotic panel. We identified susceptible phenotypes for defects in structures and functions in the outer membrane, periplasm, and cytoplasm. Overall, we show that resistance linked to the cell envelope is multifaceted and provides new targets for the development of antibiotic potentiators.
Collapse
Affiliation(s)
- Andrew M. Hogan
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Anna Motnenko
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | - Silvia T. Cardona
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| |
Collapse
|
2
|
Roszczenko-Jasińska P, Giełdoń A, Mazur D, Spodzieja M, Plichta M, Czaplewski C, Bal W, Jagusztyn-Krynicka EK, Bartosik D. Exploring the inhibitory potential of in silico-designed small peptides on Helicobacter pylori Hp0231 (DsbK), a periplasmic oxidoreductase involved in disulfide bond formation. Front Mol Biosci 2024; 10:1335704. [PMID: 38274095 PMCID: PMC10810133 DOI: 10.3389/fmolb.2023.1335704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 12/12/2023] [Indexed: 01/27/2024] Open
Abstract
Introduction: Helicobacter pylori is a bacterium that colonizes the gastric epithelium, which affects millions of people worldwide. H. pylori infection can lead to various gastrointestinal diseases, including gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. Conventional antibiotic therapies face challenges due to increasing antibiotic resistance and patient non-compliance, necessitating the exploration of alternative treatment approaches. In this study, we focused on Hp0231 (DsbK), an essential component of the H. pylori Dsb (disulfide bond) oxidative pathway, and investigated peptide-based inhibition as a potential therapeutic strategy. Methods: Three inhibitory peptides designed by computational modeling were evaluated for their effectiveness using a time-resolved fluorescence assay. We also examined the binding affinity between Hp0231 and the peptides using microscale thermophoresis. Results and discussion: Our findings demonstrate that in silico-designed synthetic peptides can effectively inhibit Hp0231-mediated peptide oxidation. Targeting Hp0231 oxidase activity could attenuate H. pylori virulence without compromising bacterial viability. Therefore, peptide-based inhibitors of Hp0231 could be candidates for the development of new targeted strategy, which does not influence the composition of the natural human microbiome, but deprive the bacterium of its pathogenic properties.
Collapse
Affiliation(s)
- Paula Roszczenko-Jasińska
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Artur Giełdoń
- Faculty of Chemistry, University of Gdańsk, Gdańsk, Poland
| | - Dominika Mazur
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | | | - Maciej Plichta
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | | | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | | | - Dariusz Bartosik
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| |
Collapse
|
3
|
Fragment-Based Lead Discovery Strategies in Antimicrobial Drug Discovery. Antibiotics (Basel) 2023; 12:antibiotics12020315. [PMID: 36830226 PMCID: PMC9951956 DOI: 10.3390/antibiotics12020315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 01/30/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023] Open
Abstract
Fragment-based lead discovery (FBLD) is a powerful application for developing ligands as modulators of disease targets. This approach strategy involves identification of interactions between low-molecular weight compounds (100-300 Da) and their putative targets, often with low affinity (KD ~0.1-1 mM) interactions. The focus of this screening methodology is to optimize and streamline identification of fragments with higher ligand efficiency (LE) than typical high-throughput screening. The focus of this review is on the last half decade of fragment-based drug discovery strategies that have been used for antimicrobial drug discovery.
Collapse
|
4
|
Whitehouse RL, Alwan WS, Ilyichova OV, Taylor AJ, Chandrashekaran IR, Mohanty B, Doak BC, Scanlon MJ. Fragment screening libraries for the identification of protein hot spots and their minimal binding pharmacophores. RSC Med Chem 2023; 14:135-143. [PMID: 36760747 PMCID: PMC9890547 DOI: 10.1039/d2md00253a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 11/11/2022] [Indexed: 11/30/2022] Open
Abstract
Fragment-based drug design relies heavily on structural information for the elaboration and optimisation of hits. The ability to identify neighbouring binding hot spots, energetically favourable interactions and conserved binding motifs in protein structures through X-ray crystallography can inform the evolution of fragments into lead-like compounds through structure-based design. The composition of fragment libraries can be designed and curated to fit this purpose and herein, we describe and compare screening libraries containing compounds comprising between 2 and 18 heavy atoms. We evaluate the properties of the compounds in these libraries and assess their ability to probe protein surfaces for binding hot spots.
Collapse
Affiliation(s)
- Rebecca L Whitehouse
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
| | - Wesam S Alwan
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
| | - Olga V Ilyichova
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
- Australian Synchrotron, ANSTO Clayton VIC 3168 Australia
- ARC Training Centre for Fragment Based Design, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
| | - Ashley J Taylor
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
| | - Indu R Chandrashekaran
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
- ARC Training Centre for Fragment Based Design, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
- Monash Fragment Platform, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
| | - Biswaranjan Mohanty
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
| | - Bradley C Doak
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
- ARC Training Centre for Fragment Based Design, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
- Monash Fragment Platform, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
- ARC Training Centre for Fragment Based Design, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
- Monash Fragment Platform, Monash Institute of Pharmaceutical Sciences, Monash University Parkville VIC 3052 Australia
| |
Collapse
|
5
|
Methyl probes in proteins for determining ligand binding mode in weak protein-ligand complexes. Sci Rep 2022; 12:11231. [PMID: 35789157 PMCID: PMC9253027 DOI: 10.1038/s41598-022-13561-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/25/2022] [Indexed: 11/11/2022] Open
Abstract
Structures of protein–ligand complexes provide critical information for drug design. Most protein–ligand complex structures are determined using X-ray crystallography, but where crystallography is not able to generate a structure for a complex, NMR is often the best alternative. However, the available tools to enable rapid and robust structure determination of protein–ligand complexes by NMR are currently limited. This leads to situations where projects are either discontinued or pursued without structural data, rendering the task more difficult. We previously reported the NMR Molecular Replacement (NMR2) approach that allows the structure of a protein–ligand complex to be determined without requiring the cumbersome task of protein resonance assignment. Herein, we describe the NMR2 approach to determine the binding pose of a small molecule in a weak protein–ligand complex by collecting sparse protein methyl-to-ligand NOEs from a selectively labeled protein sample and an unlabeled ligand. In the selective labeling scheme all methyl containing residues of the protein are protonated in an otherwise deuterated background. This allows measurement of intermolecular NOEs with greater sensitivity using standard NOESY pulse sequences instead of isotope-filtered NMR experiments. This labelling approach is well suited to the NMR2 approach and extends its utility to include larger protein–ligand complexes.
Collapse
|
6
|
Gobinath P, Packialakshmi P, Ali D, Alarifi S, Gurusamy R, Idhayadhulla A, SurendraKumar R. Nanobased Antibacterial Drug Discovery to Treat Skin Infections o f Staphylococcus aureus Using Moringa oleifera-Assisted Zinc Oxide Nanoparticle and Molecular Simulation Study. BIOMED RESEARCH INTERNATIONAL 2022; 2022:7228259. [PMID: 35187170 PMCID: PMC8853801 DOI: 10.1155/2022/7228259] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/02/2021] [Accepted: 01/16/2022] [Indexed: 11/18/2022]
Abstract
In addition to the physical barrier, the epidermis acts as a natural barrier against microbial proliferation. It is prone to bacterial infections on the skin and in the nose, such as Staphylococcus aureus, as well as a variety of other skin illnesses. Green nanomaterial production, which eliminates the use of harmful chemicals while simultaneously reducing time, is gaining popularity in the nanotechnology area. Using the leaf extract of the pharmacologically valuable plant Moringa oleifera, we described a green synthesis of ZnO NPs (zinc oxide nanoparticles). ZnO NPs had a particle size of 201.6 nm and a zeta potential of -56.80 mV, respectively. A novel aminoketone antibacterial medication was synthesized and tested for antibacterial activity using ZnO NPs as a phytocatalyst in this work. This method produces high yields while maintaining efficient and gentle reaction conditions. Moringa oleifera extract can reduce ZnO to ZnO NPs in a straightforward manner. FT-IR, 1H-NMR, 13C-NMR, mass spectra, elemental analysis, and morphological analysis were used to synthesize and describe the antibacterial medicines (1a-1g) and (2a-2g). In addition, antibacterial activity was evaluated against bacteria such as Enterococcus faecalis and Staphylococcus aureus, and compound 1c (63 μg/mL, E. faecalis) and compound 2e (0.12 μg/mL, S. aureus) were found to be very active when compared to other medications. mupirocin is used as a reference. In addition, studies of in silico molecular docking for the bacterial DsbA protein were conducted. The strong molecules 1c (-4.3 kcal/mol) and 2e (-5.1 kcal/mol) exhibit a high binding affinity through hydrogen bonding, according to docking tests.
Collapse
Affiliation(s)
- Perumal Gobinath
- PG & Research, Department of Chemistry, Nehru Memorial College (Affiliated Bharathidasan University), Puthanamapatti, Tamilnadu 621007, India
| | - Ponnusamy Packialakshmi
- PG & Research, Department of Chemistry, Nehru Memorial College (Affiliated Bharathidasan University), Puthanamapatti, Tamilnadu 621007, India
| | - Daoud Ali
- Department of Zoology, College of Sciences, King Saud University (KSU), P.O. Box 2455, 11451 Riyadh, Saudi Arabia
| | - Saud Alarifi
- Department of Zoology, College of Sciences, King Saud University (KSU), P.O. Box 2455, 11451 Riyadh, Saudi Arabia
| | - Raman Gurusamy
- Department of Life Sciences, Yeungnam University, Gyeongsan, 38541 Gyeongsan-buk, Republic of Korea
| | - Akbar Idhayadhulla
- PG & Research, Department of Chemistry, Nehru Memorial College (Affiliated Bharathidasan University), Puthanamapatti, Tamilnadu 621007, India
| | - Radhakrishnan SurendraKumar
- PG & Research, Department of Chemistry, Nehru Memorial College (Affiliated Bharathidasan University), Puthanamapatti, Tamilnadu 621007, India
| |
Collapse
|
7
|
Wang G, Mohanty B, Williams ML, Doak BC, Dhouib R, Totsika M, McMahon R, Sharma G, Zheng D, Bentley MR, Chin YKY, Horne J, Chalmers DK, Heras B, Scanlon MJ. Selective binding of small molecules to Vibrio cholerae DsbA offers a starting point for the design of novel antibacterials. ChemMedChem 2022; 17:e202100673. [PMID: 34978144 PMCID: PMC9305425 DOI: 10.1002/cmdc.202100673] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/23/2021] [Indexed: 11/25/2022]
Abstract
DsbA enzymes catalyze oxidative folding of proteins that are secreted into the periplasm of Gram‐negative bacteria, and they are indispensable for the virulence of human pathogens such as Vibrio cholerae and Escherichia coli. Therefore, targeting DsbA represents an attractive approach to control bacterial virulence. X‐ray crystal structures reveal that DsbA enzymes share a similar fold, however, the hydrophobic groove adjacent to the active site, which is implicated in substrate binding, is shorter and flatter in the structure of V. cholerae DsbA (VcDsbA) compared to E. coli DsbA (EcDsbA). The flat and largely featureless nature of this hydrophobic groove is challenging for the development of small molecule inhibitors. Using fragment‐based screening approaches, we have identified a novel small molecule, based on the benzimidazole scaffold, that binds to the hydrophobic groove of oxidized VcDsbA with a KD of 446±10 μM. The same benzimidazole compound has ∼8‐fold selectivity for VcDsbA over EcDsbA and binds to oxidized EcDsbA, with KD>3.5 mM. We generated a model of the benzimidazole complex with VcDsbA using NMR data but were unable to determine the structure of the benzimidazole bound EcDsbA using either NMR or X‐ray crystallography. Therefore, a structural basis for the observed selectivity is unclear. To better understand ligand binding to these two enzymes we crystallized each of them in complex with a known ligand, the bile salt sodium taurocholate. The crystal structures show that taurocholate adopts different binding poses in complex with VcDsbA and EcDsbA, and reveal the protein‐ligand interactions that stabilize the different modes of binding. This work highlights the capacity of fragment‐based drug discovery to identify inhibitors of challenging protein targets. In addition, it provides a starting point for development of more potent and specific VcDsbA inhibitors that act through a novel anti‐virulence mechanism.
Collapse
Affiliation(s)
- Geqing Wang
- La Trobe University - Bundoora Campus: La Trobe University, Department of Biochemistry and Genetics, AUSTRALIA
| | | | - Martin L Williams
- Monash Institute of Pharmaceutical Sciences, Medicinal Chemistry, AUSTRALIA
| | - Bradley C Doak
- Monash Institute of Pharmaceutical Sciences, Medicinal Chemistry, AUSTRALIA
| | - Rabeb Dhouib
- Queensland University of Technology, School of Biomedical Sciences, AUSTRALIA
| | - Makrina Totsika
- Queensland University of Technology, School of Biomedical Sciences, AUSTRALIA
| | - Roisin McMahon
- Griffith University, Griffith Institute for Drug Discovery, AUSTRALIA
| | - Gaurav Sharma
- Monash Institute of Pharmaceutical Sciences, Medicinal Chemistry, AUSTRALIA
| | - Dan Zheng
- Monash Institute of Pharmaceutical Sciences, Medicinal Chemistry, AUSTRALIA
| | - Matthew R Bentley
- Monash Institute of Pharmaceutical Sciences, Medicinal Chemistry, AUSTRALIA
| | - Yanni Ka-Yan Chin
- The University of Queensland, Cantre for Advanced Imaging, AUSTRALIA
| | - James Horne
- University of Tasmania, Central Science Laboratory, AUSTRALIA
| | - David K Chalmers
- Monash Institute of Pharmaceutical Sciences, Medicinal Chemistry, AUSTRALIA
| | - Begoña Heras
- La Trobe University, Department of Biochemistry and Genetics, AUSTRALIA
| | - Martin Joseph Scanlon
- Monash Institute of Pharmaceutical Sciences Monash University Parkville Campus, Medicinal Chemistry, 381 Royal Parade, Monash University, 3052, Parkville, AUSTRALIA
| |
Collapse
|
8
|
Petit GA, Mohanty B, McMahon RM, Nebl S, Hilko DH, Wilde KL, Scanlon MJ, Martin JL, Halili MA. Identification and characterization of two drug-like fragments that bind to the same cryptic binding pocket of Burkholderia pseudomallei DsbA. Acta Crystallogr D Struct Biol 2022; 78:75-90. [PMID: 34981764 PMCID: PMC8725163 DOI: 10.1107/s2059798321011475] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 10/29/2021] [Indexed: 01/10/2023] Open
Abstract
Disulfide-bond-forming proteins (Dsbs) play a crucial role in the pathogenicity of many Gram-negative bacteria. Disulfide-bond-forming protein A (DsbA) catalyzes the formation of the disulfide bonds necessary for the activity and stability of multiple substrate proteins, including many virulence factors. Hence, DsbA is an attractive target for the development of new drugs to combat bacterial infections. Here, two fragments, bromophenoxy propanamide (1) and 4-methoxy-N-phenylbenzenesulfonamide (2), were identified that bind to DsbA from the pathogenic bacterium Burkholderia pseudomallei, the causative agent of melioidosis. The crystal structures of oxidized B. pseudomallei DsbA (termed BpsDsbA) co-crystallized with 1 or 2 show that both fragments bind to a hydrophobic pocket that is formed by a change in the side-chain orientation of Tyr110. This conformational change opens a `cryptic' pocket that is not evident in the apoprotein structure. This binding location was supported by 2D-NMR studies, which identified a chemical shift perturbation of the Tyr110 backbone amide resonance of more than 0.05 p.p.m. upon the addition of 2 mM fragment 1 and of more than 0.04 p.p.m. upon the addition of 1 mM fragment 2. Although binding was detected by both X-ray crystallography and NMR, the binding affinity (Kd) for both fragments was low (above 2 mM), suggesting weak interactions with BpsDsbA. This conclusion is also supported by the crystal structure models, which ascribe partial occupancy to the ligands in the cryptic binding pocket. Small fragments such as 1 and 2 are not expected to have a high energetic binding affinity due to their relatively small surface area and the few functional groups that are available for intermolecular interactions. However, their simplicity makes them ideal for functionalization and optimization. The identification of the binding sites of 1 and 2 to BpsDsbA could provide a starting point for the development of more potent novel antimicrobial compounds that target DsbA and bacterial virulence.
Collapse
Affiliation(s)
- Guillaume A. Petit
- Griffith Institute for Drug Discovery, Griffith University, Building N75, 46 Don Young Road, Nathan, QLD 4111, Australia
| | - Biswaranjan Mohanty
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- ARC Centre for Fragment-Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Sydney Analytical Core Research Facility, The University of Sydney, Sydney, NSW 2006, Australia
| | - Róisín M. McMahon
- Griffith Institute for Drug Discovery, Griffith University, Building N75, 46 Don Young Road, Nathan, QLD 4111, Australia
| | - Stefan Nebl
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - David H. Hilko
- Griffith Institute for Drug Discovery, Griffith University, Building N75, 46 Don Young Road, Nathan, QLD 4111, Australia
| | - Karyn L. Wilde
- National Deuteration Facility, Australian Nuclear Science and Technology Organization (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Martin J. Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- ARC Centre for Fragment-Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Jennifer L. Martin
- Griffith Institute for Drug Discovery, Griffith University, Building N75, 46 Don Young Road, Nathan, QLD 4111, Australia
- Vice-Chancellor’s Unit, University of Wollongong, Building 36, Wollongong, NSW 2522, Australia
| | - Maria A. Halili
- Griffith Institute for Drug Discovery, Griffith University, Building N75, 46 Don Young Road, Nathan, QLD 4111, Australia
| |
Collapse
|
9
|
Novel Amiloride Derivatives That Inhibit Bacterial Motility across Multiple Strains and Stator Types. J Bacteriol 2021; 203:e0036721. [PMID: 34516280 DOI: 10.1128/jb.00367-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterial flagellar motor (BFM) is a protein complex that confers motility to cells and contributes to survival and virulence. The BFM consists of stators that are ion-selective membrane protein complexes and a rotor that directly connects to a large filament, acting as a propeller. The stator complexes couple ion transit across the membrane to torque that drives rotation of the motor. The most common ion gradients that drive BFM rotation are protons (H+) and sodium ions (Na+). The sodium-powered stators, like those in the PomA/PomB stator complex of Vibrio spp., can be inhibited by sodium channel inhibitors, in particular, by phenamil, a potent and widely used inhibitor. However, relatively few new sodium motility inhibitors have been described since the discovery of phenamil. In this study, we characterized two possible motility inhibitors, HM2-16F and BB2-50F, from a small library of previously reported amiloride derivatives. We used three approaches: effect on rotation of tethered cells, effect on free-swimming bacteria, and effect on rotation of marker beads. We showed that both HM2-16F and BB2-50F stopped rotation of tethered cells driven by Na+ motors comparable to phenamil at matching concentrations and could also stop rotation of tethered cells driven by H+ motors. Bead measurements in the presence and absence of stators confirmed that the compounds did not inhibit rotation via direct association with the stator, in contrast to the established mode of action of phenamil. Overall, HM2-16F and BB2-50F stopped swimming in both Na+ and H+ stator types and in pathogenic and nonpathogenic strains. IMPORTANCE Here, we characterized two novel amiloride derivatives in the search for antimicrobial compounds that target bacterial motility. These compounds were shown to inhibit flagellar motility at 10 μM across multiple strains: from nonpathogenic Escherichia coli with flagellar rotation driven by proton or chimeric sodium-powered stators, to proton-powered pathogenic E. coli (enterohemorrhagic E. coli or uropathogenic E. coli [EHEC or UPEC, respectively]), and finally, sodium-powered Vibrio alginolyticus. Broad antimotility compounds such as these are important tools in our efforts to control virulence of pathogens in health and agricultural settings.
Collapse
|
10
|
Santos-Martin C, Wang G, Subedi P, Hor L, Totsika M, Paxman JJ, Heras B. Structural bioinformatic analysis of DsbA proteins and their pathogenicity associated substrates. Comput Struct Biotechnol J 2021; 19:4725-4737. [PMID: 34504665 PMCID: PMC8405906 DOI: 10.1016/j.csbj.2021.08.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/12/2021] [Accepted: 08/12/2021] [Indexed: 01/02/2023] Open
Abstract
The disulfide bond (DSB) forming system and in particular DsbA, is a key bacterial oxidative folding catalyst. Due to its role in promoting the correct assembly of a wide range of virulence factors required at different stages of the infection process, DsbA is a master virulence rheostat, making it an attractive target for the development of new virulence blockers. Although DSB systems have been extensively studied across different bacterial species, to date, little is known about how DsbA oxidoreductases are able to recognize and interact with such a wide range of substrates. This review summarizes the current knowledge on the DsbA enzymes, with special attention on their interaction with the partner oxidase DsbB and substrates associated with bacterial virulence. The structurally and functionally diverse set of bacterial proteins that rely on DsbA-mediated disulfide bond formation are summarized. Local sequence and secondary structure elements of these substrates are analyzed to identify common elements recognized by DsbA enzymes. This not only provides information on protein folding systems in bacteria but also offers tools for identifying new DsbA substrates and informs current efforts aimed at developing DsbA targeted anti-microbials.
Collapse
Affiliation(s)
- Carlos Santos-Martin
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Australia
| | - Geqing Wang
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Australia
| | - Pramod Subedi
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Australia
| | - Lilian Hor
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Australia
| | - Makrina Totsika
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Australia
| | - Jason John Paxman
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Australia
| | - Begoña Heras
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Australia
| |
Collapse
|
11
|
Eckels EC, Chaudhuri D, Chakraborty S, Echelman DJ, Haldar S. DsbA is a redox-switchable mechanical chaperone. Chem Sci 2021; 12:11109-11120. [PMID: 34522308 PMCID: PMC8386657 DOI: 10.1039/d1sc03048e] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 07/17/2021] [Indexed: 12/18/2022] Open
Abstract
DsbA is a ubiquitous bacterial oxidoreductase that associates with substrates during and after translocation, yet its involvement in protein folding and translocation remains an open question. Here we demonstrate a redox-controlled chaperone activity of DsbA, on both cysteine-containing and cysteine-free substrates, using magnetic tweezers-based single molecule force spectroscopy that enables independent measurements of oxidoreductase activity and chaperone behavior. Interestingly we found that this chaperone activity is tuned by the oxidation state of DsbA; oxidized DsbA is a strong promoter of folding, but the effect is weakened by the reduction of the catalytic CXXC motif. We further localize the chaperone binding site of DsbA using a seven-residue peptide which effectively blocks the chaperone activity. We found that the DsbA assisted folding of proteins in the periplasm generates enough mechanical work to decrease the ATP consumption needed for periplasmic translocation by up to 33%.
Collapse
Affiliation(s)
- Edward C Eckels
- Department of Biological Sciences, Columbia University New York NY 10027 USA
- Department of Internal Medicine, Columbia University Medical Center New York NY 10032 USA
| | - Deep Chaudhuri
- Department of Biological Sciences, Ashoka University Sonepat Haryana 131029 India
| | - Soham Chakraborty
- Department of Biological Sciences, Ashoka University Sonepat Haryana 131029 India
| | - Daniel J Echelman
- Department of Biological Sciences, Columbia University New York NY 10027 USA
| | - Shubhasis Haldar
- Department of Biological Sciences, Ashoka University Sonepat Haryana 131029 India
| |
Collapse
|
12
|
Elaboration of a benzofuran scaffold and evaluation of binding affinity and inhibition of Escherichia coli DsbA: A fragment-based drug design approach to novel antivirulence compounds. Bioorg Med Chem 2021; 45:116315. [PMID: 34364222 DOI: 10.1016/j.bmc.2021.116315] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 11/20/2022]
Abstract
Bacterial thiol-disulfide oxidoreductase DsbA is essential for bacterial virulence factor assembly and has been identified as a viable antivirulence target. Herein, we report a structure-based elaboration of a benzofuran hit that bound to the active site groove of Escherichia coli DsbA. Substituted phenyl groups were installed at the 5- and 6-position of the benzofuran using Suzuki-Miyaura coupling. HSQC NMR titration experiments showed dissociation constants of this series in the high µM to low mM range and X-ray crystallography produced three co-structures, showing binding in the hydrophobic groove, comparable with that of the previously reported benzofurans. The 6-(m-methoxy)phenyl analogue (2b), which showed a promising binding pose, was chosen for elaboration from the C-2 position. The 2,6-disubstituted analogues bound to the hydrophobic region of the binding groove and the C-2 groups extended into the more polar, previously un-probed, region of the binding groove. Biochemical analysis of the 2,6-disubsituted analogues showed they inhibited DsbA oxidation activity in vitro. The results indicate the potential to develop the elaborated benzofuran series into a novel class of antivirulence compounds.
Collapse
|
13
|
Dhouib R, Vagenas D, Hong Y, Verderosa AD, Martin JL, Heras B, Totsika M. Antivirulence DsbA inhibitors attenuate Salmonella enterica serovar Typhimurium fitness without detectable resistance. FASEB Bioadv 2021; 3:231-242. [PMID: 33842848 PMCID: PMC8019255 DOI: 10.1096/fba.2020-00100] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/22/2020] [Accepted: 01/06/2021] [Indexed: 11/15/2022] Open
Abstract
Inhibition of the DiSulfide Bond (DSB) oxidative protein folding machinery, a major facilitator of virulence in Gram‐negative bacteria, represents a promising antivirulence strategy. We previously developed small molecule inhibitors of DsbA from Escherichia coli K‐12 (EcDsbA) and showed that they attenuate virulence of Gram‐negative pathogens by directly inhibiting multiple diverse DsbA homologues. Here we tested the evolutionary robustness of DsbA inhibitors as antivirulence antimicrobials against Salmonella enterica serovar Typhimurium under pathophysiological conditions in vitro. We show that phenylthiophene DsbA inhibitors slow S. Typhimurium growth in minimal media, phenocopying S. Typhimurium isogenic dsbA null mutants. Through passaging experiments, we found that DsbA inhibitor resistance was not induced under conditions that rapidly induced resistance to ciprofloxacin, an antibiotic commonly used to treat Salmonella infections. Furthermore, no mutations were identified in the dsbA gene of inhibitor‐treated S. Typhimurium, and S. Typhimurium virulence remained susceptible to DsbA inhibitors. Our work demonstrates that under in vitro pathophysiological conditions, DsbA inhibitors can have both antivirulence and antibiotic action. Importantly, our finding that DsbA inhibitors appear to be evolutionarily robust offers promise for their further development as next‐generation antimicrobials against Gram‐negative pathogens.
Collapse
Affiliation(s)
- Rabeb Dhouib
- Institute of Health and Biomedical Innovation School of Biomedical Sciences Queensland University of Technology Herston QLD Australia.,Centre for Immunology and Infection Control School of Biomedical Sciences Queensland University of Technology Herston QLD Australia
| | - Dimitrios Vagenas
- Institute of Health and Biomedical Innovation School of Biomedical Sciences Queensland University of Technology Herston QLD Australia
| | - Yaoqin Hong
- Institute of Health and Biomedical Innovation School of Biomedical Sciences Queensland University of Technology Herston QLD Australia.,Centre for Immunology and Infection Control School of Biomedical Sciences Queensland University of Technology Herston QLD Australia
| | - Anthony D Verderosa
- Institute of Health and Biomedical Innovation School of Biomedical Sciences Queensland University of Technology Herston QLD Australia.,Centre for Immunology and Infection Control School of Biomedical Sciences Queensland University of Technology Herston QLD Australia
| | - Jennifer L Martin
- Griffith Institute for Drug Discovery Griffith University Nathan QLD Australia.,University of Wollongong Wollongong NSW Australia
| | - Begoña Heras
- La Trobe Institute for Molecular Science La Trobe University Bundoora VIC Australia
| | - Makrina Totsika
- Institute of Health and Biomedical Innovation School of Biomedical Sciences Queensland University of Technology Herston QLD Australia.,Centre for Immunology and Infection Control School of Biomedical Sciences Queensland University of Technology Herston QLD Australia
| |
Collapse
|
14
|
Lim KYL, Mullally CA, Haese EC, Kibble EA, McCluskey NR, Mikucki EC, Thai VC, Stubbs KA, Sarkar-Tyson M, Kahler CM. Anti-Virulence Therapeutic Approaches for Neisseria gonorrhoeae. Antibiotics (Basel) 2021; 10:antibiotics10020103. [PMID: 33494538 PMCID: PMC7911339 DOI: 10.3390/antibiotics10020103] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 01/15/2023] Open
Abstract
While antimicrobial resistance (AMR) is seen in both Neisseria gonorrhoeae and Neisseria meningitidis, the former has become resistant to commonly available over-the-counter antibiotic treatments. It is imperative then to develop new therapies that combat current AMR isolates whilst also circumventing the pathways leading to the development of AMR. This review highlights the growing research interest in developing anti-virulence therapies (AVTs) which are directed towards inhibiting virulence factors to prevent infection. By targeting virulence factors that are not essential for gonococcal survival, it is hypothesized that this will impart a smaller selective pressure for the emergence of resistance in the pathogen and in the microbiome, thus avoiding AMR development to the anti-infective. This review summates the current basis of numerous anti-virulence strategies being explored for N. gonorrhoeae.
Collapse
Affiliation(s)
- Katherine Y. L. Lim
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
| | - Christopher A. Mullally
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
| | - Ethan C. Haese
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
| | - Emily A. Kibble
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - Nicolie R. McCluskey
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - Edward C. Mikucki
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
| | - Van C. Thai
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
| | - Keith A. Stubbs
- School of Molecular Sciences, University of Western Australia, Crawley, WA 6009, Australia;
| | - Mitali Sarkar-Tyson
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
| | - Charlene M. Kahler
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (K.Y.L.L.); (C.A.M.); (E.C.H.); (E.A.K.); (N.R.M.); (E.C.M.); (V.C.T.); (M.S.-T.)
- Correspondence:
| |
Collapse
|
15
|
A high-throughput cell-based assay pipeline for the preclinical development of bacterial DsbA inhibitors as antivirulence therapeutics. Sci Rep 2021; 11:1569. [PMID: 33452354 PMCID: PMC7810732 DOI: 10.1038/s41598-021-81007-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/17/2020] [Indexed: 11/23/2022] Open
Abstract
Antibiotics are failing fast, and the development pipeline remains alarmingly dry. New drug research and development is being urged by world health officials, with new antibacterials against multidrug-resistant Gram-negative pathogens as the highest priority. Antivirulence drugs, which inhibit bacterial pathogenicity factors, are a class of promising antibacterials, however, their development is stifled by lack of standardised preclinical testing akin to what guides antibiotic development. The lack of established target-specific microbiological assays amenable to high-throughput, often means that cell-based testing of virulence inhibitors is absent from the discovery (hit-to-lead) phase, only to be employed at later-stages of lead optimization. Here, we address this by establishing a pipeline of bacterial cell-based assays developed for the identification and early preclinical evaluation of DsbA inhibitors, previously identified by biophysical and biochemical assays. Inhibitors of DsbA block oxidative protein folding required for virulence factor folding in pathogens. Here we use existing Escherichia coli DsbA inhibitors and uropathogenic E. coli (UPEC) as a model pathogen, to demonstrate that the combination of a cell-based sulfotransferase assay and a motility assay (both DsbA reporter assays), modified for a higher throughput format, can provide a robust and target-specific platform for the identification and evaluation of DsbA inhibitors.
Collapse
|
16
|
Deshmukh SU, Toche RB, Takate SJ, Salve SP, Sabnis RW. Synthesis of novel thiazol‐5‐ylpyrimidine derivatives and their antimicrobial evaluation. J Heterocycl Chem 2020. [DOI: 10.1002/jhet.4116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sanjay U. Deshmukh
- Department of Chemistry KRT Arts, BH Commerce & AM Science College Nashik India
| | - Raghunath B. Toche
- Department of Chemistry Dadasheb Bidkar Arts, Science & Commerce College Peth, Nashik‐422208 India
| | - Sushama J. Takate
- Department of Chemistry New Art, Commerce and Science College Ahmednagar India
| | - Supriya P. Salve
- Department of Chemistry New Art, Commerce and Science College Ahmednagar India
| | - Ram W. Sabnis
- Patent Law Department Georgia‐Pacific LLC Atlanta Georgia USA
| |
Collapse
|
17
|
Nebl S, Alwan WS, Williams ML, Sharma G, Taylor A, Doak BC, Wilde KL, McMahon RM, Halili MA, Martin JL, Capuano B, Fenwick RB, Mohanty B, Scanlon MJ. NMR fragment screening reveals a novel small molecule binding site near the catalytic surface of the disulfide-dithiol oxidoreductase enzyme DsbA from Burkholderia pseudomallei. JOURNAL OF BIOMOLECULAR NMR 2020; 74:595-611. [PMID: 32761504 DOI: 10.1007/s10858-020-00339-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
The presence of suitable cavities or pockets on protein structures is a general criterion for a therapeutic target protein to be classified as 'druggable'. Many disease-related proteins that function solely through protein-protein interactions lack such pockets, making development of inhibitors by traditional small-molecule structure-based design methods much more challenging. The 22 kDa bacterial thiol oxidoreductase enzyme, DsbA, from the gram-negative bacterium Burkholderia pseudomallei (BpsDsbA) is an example of one such target. The crystal structure of oxidized BpsDsbA lacks well-defined surface pockets. BpsDsbA is required for the correct folding of numerous virulence factors in B. pseudomallei, and genetic deletion of dsbA significantly attenuates B. pseudomallei virulence in murine infection models. Therefore, BpsDsbA is potentially an attractive drug target. Herein we report the identification of a small molecule binding site adjacent to the catalytic site of oxidized BpsDsbA. 1HN CPMG relaxation dispersion NMR measurements suggest that the binding site is formed transiently through protein dynamics. Using fragment-based screening, we identified a small molecule that binds at this site with an estimated affinity of KD ~ 500 µM. This fragment inhibits BpsDsbA enzymatic activity in vitro. The binding mode of this molecule has been characterized by NMR data-driven docking using HADDOCK. These data provide a starting point towards the design of more potent small molecule inhibitors of BpsDsbA.
Collapse
Affiliation(s)
- Stefan Nebl
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Wesam S Alwan
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Martin L Williams
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Gaurav Sharma
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Ashley Taylor
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Bradley C Doak
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Karyn L Wilde
- National Deuteration Facility, Australian Nuclear Science and Technology Organization (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Róisín M McMahon
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Australia
| | - Maria A Halili
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Australia
| | - Jennifer L Martin
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Australia
- Vice-Chancellor's Unit, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Ben Capuano
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - R Bryn Fenwick
- Department of Integrative Structural and Computational Biology, Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Biswaranjan Mohanty
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia.
- ARC Centre for Fragment-Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia.
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia.
- ARC Centre for Fragment-Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia.
| |
Collapse
|
18
|
Pandeya A, Ojo I, Alegun O, Wei Y. Periplasmic Targets for the Development of Effective Antimicrobials against Gram-Negative Bacteria. ACS Infect Dis 2020; 6:2337-2354. [PMID: 32786281 PMCID: PMC8187054 DOI: 10.1021/acsinfecdis.0c00384] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Antibiotic resistance has emerged as a serious threat to global public health in recent years. Lack of novel antimicrobials, especially new classes of compounds, further aggravates the situation. For Gram-negative bacteria, their double layered cell envelope and an array of efflux pumps act as formidable barriers for antimicrobials to penetrate. While cytoplasmic targets are hard to reach, proteins in the periplasm are clearly more accessible, as the drug only needs to breach the outer membrane. In this review, we summarized recent efforts on the validation and testing of periplasmic proteins as potential antimicrobial targets and the development of related inhibitors that either inhibit the growth of a bacterial pathogen or reduce its virulence during interaction with host cells. We conclude that the periplasm contains a promising pool of novel antimicrobial targets that should be scrutinized more closely for the development of effective treatment against multidrug-resistant Gram-negative bacteria.
Collapse
Affiliation(s)
- Ankit Pandeya
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Isoiza Ojo
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Olaniyi Alegun
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Yinan Wei
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| |
Collapse
|
19
|
Bentley MR, Ilyichova OV, Wang G, Williams ML, Sharma G, Alwan WS, Whitehouse RL, Mohanty B, Scammells PJ, Heras B, Martin JL, Totsika M, Capuano B, Doak BC, Scanlon MJ. Rapid Elaboration of Fragments into Leads by X-ray Crystallographic Screening of Parallel Chemical Libraries (REFiLX). J Med Chem 2020; 63:6863-6875. [DOI: 10.1021/acs.jmedchem.0c00111] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Matthew R. Bentley
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Olga V. Ilyichova
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Geqing Wang
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Martin L. Williams
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Gaurav Sharma
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Wesam S. Alwan
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Rebecca L. Whitehouse
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Biswaranjan Mohanty
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- ARC Training Centre for Fragment Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Peter J. Scammells
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Begoña Heras
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Jennifer L. Martin
- Griffith Institute for Drug Discovery, Building N75, Brisbane Innovation Park, Don Young Road, Nathan, QLD 4111, Australia
- Vice-Chancellor’s Unit, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
| | - Makrina Totsika
- School of Biomedical Sciences, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - Ben Capuano
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- ARC Training Centre for Fragment Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Bradley C. Doak
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- ARC Training Centre for Fragment Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Monash Fragment Platform, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Martin J. Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- ARC Training Centre for Fragment Based Design, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Monash Fragment Platform, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| |
Collapse
|
20
|
The Fragment-Based Development of a Benzofuran Hit as a New Class of Escherichia coli DsbA Inhibitors. Molecules 2019; 24:molecules24203756. [PMID: 31635355 PMCID: PMC6832960 DOI: 10.3390/molecules24203756] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/13/2019] [Accepted: 10/15/2019] [Indexed: 11/17/2022] Open
Abstract
A fragment-based drug discovery approach was taken to target the thiol-disulfide oxidoreductase enzyme DsbA from Escherichia coli (EcDsbA). This enzyme is critical for the correct folding of virulence factors in many pathogenic Gram-negative bacteria, and small molecule inhibitors can potentially be developed as anti-virulence compounds. Biophysical screening of a library of fragments identified several classes of fragments with affinity to EcDsbA. One hit with high mM affinity, 2-(6-bromobenzofuran-3-yl)acetic acid (6), was chemically elaborated at several positions around the scaffold. X-ray crystal structures of the elaborated analogues showed binding in the hydrophobic binding groove adjacent to the catalytic disulfide bond of EcDsbA. Binding affinity was calculated based on NMR studies and compounds 25 and 28 were identified as the highest affinity binders with dissociation constants (KD) of 326 ± 25 and 341 ± 57 µM respectively. This work suggests the potential to develop benzofuran fragments into a novel class of EcDsbA inhibitors.
Collapse
|
21
|
Sutoh S, Uemura Y, Yamaguchi Y, Kiyotou A, Sugihara R, Nagayasu M, Kurokawa M, Ito K, Tsunekawa N, Nemoto M, Inagaki K, Tamura T. Redox-tuning of oxidizing disulfide oxidoreductase generates a potent disulfide isomerase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:194-201. [DOI: 10.1016/j.bbapap.2018.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 11/27/2018] [Accepted: 12/14/2018] [Indexed: 11/16/2022]
|
22
|
Christensen S, McMahon RM, Martin JL, Huston WM. Life inside and out: making and breaking protein disulfide bonds in Chlamydia. Crit Rev Microbiol 2019; 45:33-50. [PMID: 30663449 DOI: 10.1080/1040841x.2018.1538933] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Disulphide bonds are widely used among all domains of life to provide structural stability to proteins and to regulate enzyme activity. Chlamydia spp. are obligate intracellular bacteria that are especially dependent on the formation and degradation of protein disulphide bonds. Members of the genus Chlamydia have a unique biphasic developmental cycle alternating between two distinct cell types; the extracellular infectious elementary body (EB) and the intracellular replicating reticulate body. The proteins in the envelope of the EB are heavily cross-linked with disulphides and this is known to be critical for this infectious phase. In this review, we provide a comprehensive summary of what is known about the redox state of chlamydial envelope proteins throughout the developmental cycle. We focus especially on the factors responsible for degradation and formation of disulphide bonds in Chlamydia and how this system compares with redox regulation in other organisms. Focussing on the unique biology of Chlamydia enables us to provide important insights into how specialized suites of disulphide bond (Dsb) proteins cater for specific bacterial environments and lifecycles.
Collapse
Affiliation(s)
- Signe Christensen
- a Division of Chemistry and Structural Biology , Institute for Molecular Bioscience, University of Queensland , St. Lucia , QLD , Australia.,b Griffith Institute for Drug Discovery, Griffith University , Nathan , QLD , Australia
| | - Róisín M McMahon
- b Griffith Institute for Drug Discovery, Griffith University , Nathan , QLD , Australia
| | - Jennifer L Martin
- b Griffith Institute for Drug Discovery, Griffith University , Nathan , QLD , Australia
| | - Wilhelmina M Huston
- c School of Life Sciences , University of Technology Sydney , Ultimo , NSW , Australia
| |
Collapse
|
23
|
Lakemeyer M, Zhao W, Mandl FA, Hammann P, Sieber SA. Thinking Outside the Box-Novel Antibacterials To Tackle the Resistance Crisis. Angew Chem Int Ed Engl 2018; 57:14440-14475. [PMID: 29939462 DOI: 10.1002/anie.201804971] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Indexed: 12/13/2022]
Abstract
The public view on antibiotics as reliable medicines changed when reports about "resistant superbugs" appeared in the news. While reasons for this resistance development are easily spotted, solutions for re-establishing effective antibiotics are still in their infancy. This Review encompasses several aspects of the antibiotic development pipeline from very early strategies to mature drugs. An interdisciplinary overview is given of methods suitable for mining novel antibiotics and strategies discussed to unravel their modes of action. Select examples of antibiotics recently identified by using these platforms not only illustrate the efficiency of these measures, but also highlight promising clinical candidates with therapeutic potential. Furthermore, the concept of molecules that disarm pathogens by addressing gatekeepers of virulence will be covered. The Review concludes with an evaluation of antibacterials currently in clinical development. Overall, this Review aims to connect select innovative antimicrobial approaches to stimulate interdisciplinary partnerships between chemists from academia and industry.
Collapse
Affiliation(s)
- Markus Lakemeyer
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Weining Zhao
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Franziska A Mandl
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Peter Hammann
- R&D Therapeutic Area Infectious Diseases, Sanofi-Aventis (Deutschland) GmbH, Industriepark Höchst, 65926, Frankfurt am Main, Germany
| | - Stephan A Sieber
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| |
Collapse
|
24
|
Lakemeyer M, Zhao W, Mandl FA, Hammann P, Sieber SA. Über bisherige Denkweisen hinaus - neue Wirkstoffe zur Überwindung der Antibiotika-Krise. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201804971] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Markus Lakemeyer
- Fakultät für Chemie; Lehrstuhl für Organische Chemie II, Center for Integrated Protein Science (CIPSM); Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Weining Zhao
- Fakultät für Chemie; Lehrstuhl für Organische Chemie II, Center for Integrated Protein Science (CIPSM); Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Franziska A. Mandl
- Fakultät für Chemie; Lehrstuhl für Organische Chemie II, Center for Integrated Protein Science (CIPSM); Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Peter Hammann
- R&D Therapeutic Area Infectious Diseases; Sanofi-Aventis (Deutschland) GmbH; Industriepark Höchst 65926 Frankfurt am Main Deutschland
| | - Stephan A. Sieber
- Fakultät für Chemie; Lehrstuhl für Organische Chemie II, Center for Integrated Protein Science (CIPSM); Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| |
Collapse
|
25
|
Kahler CM, Sarkar-Tyson M, Kibble EA, Stubbs KA, Vrielink A. Enzyme targets for drug design of new anti-virulence therapeutics. Curr Opin Struct Biol 2018; 53:140-150. [PMID: 30223251 DOI: 10.1016/j.sbi.2018.08.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 08/30/2018] [Accepted: 08/30/2018] [Indexed: 12/19/2022]
Abstract
Society has benefitted greatly from the use of antibiotics. Unfortunately, the misuse of these valuable molecules has resulted in increased levels of antibiotic resistance, a major global and public health issue. This resistance and the reliance on a small number of biological targets for the development of antibiotics emphasizes the need for new targets. A critical aspect guiding the development of new antimicrobials through a rational structure-guided approach is to understand the molecular structures of specific biological targets of interest. Here we give an overview of the structures of bacterial virulence enzyme targets involved in protein folding, peptidoglycan biosynthesis and cell wall modification. These include enzymes of the thiol-disulphide oxidoreductase pathway (DSB enzymes), peptidyl-proly cis/trans isomerases (Mips), enzymes from the Mur pathway and enzymes involved in lipopolysaccharide modification (EptA and ArnT). We also present progress towards inhibitor design of these targets for the development of novel anti-virulence therapeutic agents.
Collapse
Affiliation(s)
- Charlene M Kahler
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Mitali Sarkar-Tyson
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Emily A Kibble
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Keith A Stubbs
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Alice Vrielink
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia; Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
| |
Collapse
|
26
|
Smith RP, Mohanty B, Mowlaboccus S, Paxman JJ, Williams ML, Headey SJ, Wang G, Subedi P, Doak BC, Kahler CM, Scanlon MJ, Heras B. Structural and biochemical insights into the disulfide reductase mechanism of DsbD, an essential enzyme for neisserial pathogens. J Biol Chem 2018; 293:16559-16571. [PMID: 30181210 DOI: 10.1074/jbc.ra118.004847] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 08/16/2018] [Indexed: 12/13/2022] Open
Abstract
The worldwide incidence of neisserial infections, particularly gonococcal infections, is increasingly associated with antibiotic-resistant strains. In particular, extensively drug-resistant Neisseria gonorrhoeae strains that are resistant to third-generation cephalosporins are a major public health concern. There is a pressing clinical need to identify new targets for the development of antibiotics effective against Neisseria-specific processes. In this study, we report that the bacterial disulfide reductase DsbD is highly prevalent and conserved among Neisseria spp. and that this enzyme is essential for survival of N. gonorrhoeae DsbD is a membrane-bound protein that consists of two periplasmic domains, n-DsbD and c-DsbD, which flank the transmembrane domain t-DsbD. In this work, we show that the two functionally essential periplasmic domains of Neisseria DsbD catalyze electron transfer reactions through unidirectional interdomain interactions, from reduced c-DsbD to oxidized n-DsbD, and that this process is not dictated by their redox potentials. Structural characterization of the Neisseria n- and c-DsbD domains in both redox states provides evidence that steric hindrance reduces interactions between the two periplasmic domains when n-DsbD is reduced, thereby preventing a futile redox cycle. Finally, we propose a conserved mechanism of electron transfer for DsbD and define the residues involved in domain-domain recognition. Inhibitors of the interaction of the two DsbD domains have the potential to be developed as anti-neisserial agents.
Collapse
Affiliation(s)
- Roxanne P Smith
- From the Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Victoria, Australia
| | - Biswaranjan Mohanty
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3052, Victoria, Australia, and
| | - Shakeel Mowlaboccus
- the Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth 6907, Western Australia, Australia
| | - Jason J Paxman
- From the Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Victoria, Australia
| | - Martin L Williams
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3052, Victoria, Australia, and
| | - Stephen J Headey
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3052, Victoria, Australia, and
| | - Geqing Wang
- From the Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Victoria, Australia
| | - Pramod Subedi
- From the Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Victoria, Australia
| | - Bradley C Doak
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3052, Victoria, Australia, and
| | - Charlene M Kahler
- the Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth 6907, Western Australia, Australia
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3052, Victoria, Australia, and
| | - Begoña Heras
- From the Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Victoria, Australia,
| |
Collapse
|
27
|
Totsika M, Vagenas D, Paxman JJ, Wang G, Dhouib R, Sharma P, Martin JL, Scanlon MJ, Heras B. Inhibition of Diverse DsbA Enzymes in Multi-DsbA Encoding Pathogens. Antioxid Redox Signal 2018; 29:653-666. [PMID: 29237285 PMCID: PMC6067686 DOI: 10.1089/ars.2017.7104] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
AIMS DsbA catalyzes disulfide bond formation in secreted and outer membrane proteins in bacteria. In pathogens, DsbA is a major facilitator of virulence constituting a target for antivirulence antimicrobial development. However, many pathogens encode multiple and diverse DsbA enzymes for virulence factor folding during infection. The aim of this study was to determine whether our recently identified inhibitors of Escherichia coli K-12 DsbA can inhibit the diverse DsbA enzymes found in two important human pathogens and attenuate their virulence. RESULTS DsbA inhibitors from two chemical classes (phenylthiophene and phenoxyphenyl derivatives) inhibited the virulence of uropathogenic E. coli and Salmonella enterica serovar Typhimurium, encoding two and three diverse DsbA homologues, respectively. Inhibitors blocked the virulence of dsbA null mutants complemented with structurally diverse DsbL and SrgA, suggesting that they were not selective for prototypical DsbA. Structural characterization of DsbA-inhibitor complexes showed that compounds from each class bind in a similar region of the hydrophobic groove adjacent to the Cys30-Pro31-His32-Cys33 (CPHC) active site. Modeling of DsbL- and SrgA-inhibitor interactions showed that these accessory enzymes could accommodate the inhibitors in their different hydrophobic grooves, supporting our in vivo findings. Further, we identified highly conserved residues surrounding the active site for 20 diverse bacterial DsbA enzymes, which could be exploited in developing inhibitors with a broad spectrum of activity. Innovation and Conclusion: We have developed tools to analyze the specificity of DsbA inhibitors in bacterial pathogens encoding multiple DsbA enzymes. This work demonstrates that DsbA inhibitors can be developed to target diverse homologues found in bacteria. Antioxid. Redox Signal. 29, 653-666.
Collapse
Affiliation(s)
- Makrina Totsika
- 1 Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology , Queensland, Australia
| | - Dimitrios Vagenas
- 1 Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology , Queensland, Australia
| | - Jason J Paxman
- 2 Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University , Bundoora, Australia
| | - Geqing Wang
- 2 Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University , Bundoora, Australia
| | - Rabeb Dhouib
- 1 Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology , Queensland, Australia
| | - Pooja Sharma
- 3 Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Australia
| | - Jennifer L Martin
- 4 Institute for Molecular Bioscience, University of Queensland , Queensland, Australia
| | - Martin J Scanlon
- 3 Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Australia
| | - Begoña Heras
- 2 Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University , Bundoora, Australia
| |
Collapse
|
28
|
Virulence of the Melioidosis Pathogen Burkholderia pseudomallei Requires the Oxidoreductase Membrane Protein DsbB. Infect Immun 2018; 86:IAI.00938-17. [PMID: 29440370 PMCID: PMC5913862 DOI: 10.1128/iai.00938-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 02/04/2018] [Indexed: 12/26/2022] Open
Abstract
The naturally antibiotic-resistant bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a disease with stubbornly high mortality and a complex, protracted treatment regimen. The worldwide incidence of melioidosis is likely grossly underreported, though it is known to be highly endemic in northern Australia and Southeast Asia. Bacterial disulfide bond (DSB) proteins catalyze the oxidative folding and isomerization of disulfide bonds in substrate proteins. In the present study, we demonstrate that B. pseudomallei membrane protein disulfide bond protein B (BpsDsbB) forms a functional redox relay with the previously characterized virulence mediator B. pseudomallei disulfide bond protein A (BpsDsbA). Genomic analysis of diverse B. pseudomallei clinical isolates demonstrated that dsbB is a highly conserved core gene. Critically, we show that DsbB is required for virulence in B. pseudomallei. A panel of B. pseudomalleidsbB deletion strains (K96243, 576, MSHR2511, MSHR0305b, and MSHR5858) were phenotypically diverse according to the results of in vitro assays that assess hallmarks of virulence. Irrespective of their in vitro virulence phenotypes, two deletion strains were attenuated in a BALB/c mouse model of infection. A crystal structure of a DsbB-derived peptide complexed with BpsDsbA provides the first molecular characterization of their interaction. This work contributes to our broader understanding of DSB redox biology and will support the design of antimicrobial drugs active against this important family of bacterial virulence targets.
Collapse
|
29
|
A shape-shifting redox foldase contributes to Proteus mirabilis copper resistance. Nat Commun 2017; 8:16065. [PMID: 28722010 PMCID: PMC5524982 DOI: 10.1038/ncomms16065] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 05/24/2017] [Indexed: 01/11/2023] Open
Abstract
Copper resistance is a key virulence trait of the uropathogen Proteus mirabilis. Here we show that P. mirabilis ScsC (PmScsC) contributes to this defence mechanism by enabling swarming in the presence of copper. We also demonstrate that PmScsC is a thioredoxin-like disulfide isomerase but, unlike other characterized proteins in this family, it is trimeric. PmScsC trimerization and its active site cysteine are required for wild-type swarming activity in the presence of copper. Moreover, PmScsC exhibits unprecedented motion as a consequence of a shape-shifting motif linking the catalytic and trimerization domains. The linker accesses strand, loop and helical conformations enabling the sampling of an enormous folding landscape by the catalytic domains. Mutation of the shape-shifting motif abolishes disulfide isomerase activity, as does removal of the trimerization domain, showing that both features are essential to foldase function. More broadly, the shape-shifter peptide has the potential for ‘plug and play’ application in protein engineering. Bacterial disulfide isomerases shuffle incorrect disulfide bonds. Here, the authors structurally characterize the disulfide isomerase ScsC from Proteus mirabilis and identify a functionally important shape-shifting motif that allows ScsC to adopt a diverse range of conformations and enable swarming in the presence of copper stress.
Collapse
|
30
|
Bacterial thiol oxidoreductases - from basic research to new antibacterial strategies. Appl Microbiol Biotechnol 2017; 101:3977-3989. [PMID: 28409380 PMCID: PMC5403849 DOI: 10.1007/s00253-017-8291-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 12/15/2022]
Abstract
The recent, rapid increase in bacterial antimicrobial resistance has become a major public health concern. One approach to generate new classes of antibacterials is targeting virulence rather than the viability of bacteria. Proteins of the Dsb system, which play a key role in the virulence of many pathogenic microorganisms, represent potential new drug targets. The first part of the article presents current knowledge of how the Dsb system impacts function of various protein secretion systems that influence the virulence of many pathogenic bacteria. Next, the review describes methods used to study the structure, biochemistry, and microbiology of the Dsb proteins and shows how these experiments broaden our knowledge about their function. The lessons gained from basic research have led to a specific search for inhibitors blocking the Dsb networks.
Collapse
|
31
|
Fragment library screening identifies hits that bind to the non-catalytic surface of Pseudomonas aeruginosa DsbA1. PLoS One 2017; 12:e0173436. [PMID: 28346540 PMCID: PMC5367682 DOI: 10.1371/journal.pone.0173436] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 01/31/2017] [Indexed: 11/26/2022] Open
Abstract
At a time when the antibiotic drug discovery pipeline has stalled, antibiotic resistance is accelerating with catastrophic implications for our ability to treat bacterial infections. Globally we face the prospect of a future when common infections can once again kill. Anti-virulence approaches that target the capacity of the bacterium to cause disease rather than the growth or survival of the bacterium itself offer a tantalizing prospect of novel antimicrobials. They may also reduce the propensity to induce resistance by removing the strong selection pressure imparted by bactericidal or bacteriostatic agents. In the human pathogen Pseudomonas aeruginosa, disulfide bond protein A (PaDsbA1) plays a central role in the oxidative folding of virulence factors and is therefore an attractive target for the development of new anti-virulence antimicrobials. Using a fragment-based approach we have identified small molecules that bind to PaDsbA1. The fragment hits show selective binding to PaDsbA1 over the DsbA protein from Escherichia coli, suggesting that developing species-specific narrow-spectrum inhibitors of DsbA enzymes may be feasible. Structures of a co-complex of PaDsbA1 with the highest affinity fragment identified in the screen reveal that the fragment binds on the non-catalytic surface of the protein at a domain interface. This biophysical and structural data represent a starting point in the development of higher affinity compounds, which will be assessed for their potential as selective PaDsbA1 inhibitors.
Collapse
|
32
|
De Schutter JW, Morrison JP, Morrison MJ, Ciulli A, Imperiali B. Targeting Bacillosamine Biosynthesis in Bacterial Pathogens: Development of Inhibitors to a Bacterial Amino-Sugar Acetyltransferase from Campylobacter jejuni. J Med Chem 2017; 60:2099-2118. [PMID: 28182413 DOI: 10.1021/acs.jmedchem.6b01869] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The glycoproteins of selected microbial pathogens often include highly modified carbohydrates such as 2,4-diacetamidobacillosamine (diNAcBac). These glycoconjugates are involved in host-cell interactions and may be associated with the virulence of medically significant Gram-negative bacteria. In light of genetic studies demonstrating the attenuated virulence of bacterial strains in which modified carbohydrate biosynthesis enzymes have been knocked out, we are developing small molecule inhibitors of selected enzymes as tools to evaluate whether such compounds modulate virulence. We performed fragment-based and high-throughput screens against an amino-sugar acetyltransferase enzyme, PglD, involved in biosynthesis of UDP-diNAcBac in Campylobacter jejuni. Herein we report optimization of the hits into potent small molecule inhibitors (IC50 < 300 nM). Biophysical characterization shows that the best inhibitors are competitive with acetyl coenzyme A and an X-ray cocrystal structure reveals that binding is biased toward occupation of the adenine subpocket of the AcCoA binding site by an aromatic ring.
Collapse
Affiliation(s)
- Joris W De Schutter
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - James P Morrison
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Michael J Morrison
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Alessio Ciulli
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee , DD1 5EH Dundee, Scotland
| | - Barbara Imperiali
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.,Department of Biology, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
33
|
Christensen S, Grøftehauge MK, Byriel K, Huston WM, Furlong E, Heras B, Martin JL, McMahon RM. Structural and Biochemical Characterization of Chlamydia trachomatis DsbA Reveals a Cysteine-Rich and Weakly Oxidising Oxidoreductase. PLoS One 2016; 11:e0168485. [PMID: 28030602 PMCID: PMC5193440 DOI: 10.1371/journal.pone.0168485] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 11/30/2016] [Indexed: 11/24/2022] Open
Abstract
The Gram negative bacteria Chlamydia trachomatis is an obligate intracellular human pathogen that can cause pelvic inflammatory disease, infertility and blinding trachoma. C. trachomatis encodes a homolog of the dithiol oxidoreductase DsbA. Bacterial DsbA proteins introduce disulfide bonds to folding proteins providing structural bracing for secreted virulence factors, consequently these proteins are potential targets for antimicrobial drugs. Despite sharing functional and structural characteristics, the DsbA enzymes studied to date vary widely in their redox character. In this study we show that the truncated soluble form of the predicted membrane anchored protein C. trachomatis DsbA (CtDsbA) has oxidase activity and redox properties broadly similar to other characterized DsbA proteins. However CtDsbA is distinguished from other DsbAs by having six cysteines, including a second disulfide bond, and an unusual dipeptide sequence in its catalytic motif (Cys-Ser-Ala-Cys). We report the 2.7 Å crystal structure of CtDsbA revealing a typical DsbA fold, which is most similar to that of DsbA-II type proteins. Consistent with this, the catalytic surface of CtDsbA is negatively charged and lacks the hydrophobic groove found in EcDsbA and DsbAs from other enterobacteriaceae. Biochemical characterization of CtDsbA reveals it to be weakly oxidizing compared to other DsbAs and with only a mildly destabilizing active site disulfide bond. Analysis of the crystal structure suggests that this redox character is consistent with a lack of contributing factors to stabilize the active site nucleophilic thiolate relative to more oxidizing DsbA proteins.
Collapse
Affiliation(s)
- Signe Christensen
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia
| | - Morten K. Grøftehauge
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia
| | - Karl Byriel
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia
| | - Wilhelmina M. Huston
- School of Life Sciences, University of Technology Sydney, Broadway, New South Wales, Australia
| | - Emily Furlong
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia
| | - Begoña Heras
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia
| | - Jennifer L. Martin
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia
- * E-mail: (JM); (RM)
| | - Róisín M. McMahon
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia
- * E-mail: (JM); (RM)
| |
Collapse
|
34
|
Mohanty B, Williams ML, Doak BC, Vazirani M, Ilyichova O, Wang G, Bermel W, Simpson JS, Chalmers DK, King GF, Mobli M, Scanlon MJ. Determination of ligand binding modes in weak protein-ligand complexes using sparse NMR data. JOURNAL OF BIOMOLECULAR NMR 2016; 66:195-208. [PMID: 27778134 DOI: 10.1007/s10858-016-0067-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 09/29/2016] [Indexed: 06/06/2023]
Abstract
We describe a general approach to determine the binding pose of small molecules in weakly bound protein-ligand complexes by deriving distance constraints between the ligand and methyl groups from all methyl-containing residues of the protein. We demonstrate that using a single sample, which can be prepared without the use of expensive precursors, it is possible to generate high-resolution data rapidly and obtain the resonance assignments of Ile, Leu, Val, Ala and Thr methyl groups using triple resonance scalar correlation data. The same sample may be used to obtain Met εCH3 assignments using NOESY-based methods, although the superior sensitivity of NOESY using [U-13C,15N]-labeled protein makes the use of this second sample more efficient. We describe a structural model for a weakly binding ligand bound to its target protein, DsbA, derived from intermolecular methyl-to-ligand nuclear Overhauser enhancements, and demonstrate that the ability to assign all methyl resonances in the spectrum is essential to derive an accurate model of the structure. Once the methyl assignments have been obtained, this approach provides a rapid means to generate structural models for weakly bound protein-ligand complexes. Such weak complexes are often found at the beginning of programs of fragment based drug design and can be challenging to characterize using X-ray crystallography.
Collapse
Affiliation(s)
- Biswaranjan Mohanty
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Martin L Williams
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Bradley C Doak
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Mansha Vazirani
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Olga Ilyichova
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Geqing Wang
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
- La Trobe Institute for Molecular Bioscience, La Trobe University, Bundoora, VIC, 3083, Australia
| | - Wolfgang Bermel
- Bruker Biospin GmbH, Silberstreifen, 76287, Rheinstetten, Germany
| | - Jamie S Simpson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - David K Chalmers
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Mehdi Mobli
- Centre for Advanced Imaging, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, 3052, Australia.
| |
Collapse
|
35
|
Smith RP, Paxman JJ, Scanlon MJ, Heras B. Targeting Bacterial Dsb Proteins for the Development of Anti-Virulence Agents. Molecules 2016; 21:molecules21070811. [PMID: 27438817 PMCID: PMC6273893 DOI: 10.3390/molecules21070811] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 05/21/2016] [Accepted: 05/25/2016] [Indexed: 11/22/2022] Open
Abstract
Recent years have witnessed a dramatic increase in bacterial antimicrobial resistance and a decline in the development of novel antibiotics. New therapeutic strategies are urgently needed to combat the growing threat posed by multidrug resistant bacterial infections. The Dsb disulfide bond forming pathways are potential targets for the development of antimicrobial agents because they play a central role in bacterial pathogenesis. In particular, the DsbA/DsbB system catalyses disulfide bond formation in a wide array of virulence factors, which are essential for many pathogens to establish infections and cause disease. These redox enzymes are well placed as antimicrobial targets because they are taxonomically widespread, share low sequence identity with human proteins, and many years of basic research have provided a deep molecular understanding of these systems in bacteria. In this review, we discuss disulfide bond catalytic pathways in bacteria and their significance in pathogenesis. We also review the use of different approaches to develop inhibitors against Dsb proteins as potential anti-virulence agents, including fragment-based drug discovery, high-throughput screening and other structure-based drug discovery methods.
Collapse
Affiliation(s)
- Roxanne P Smith
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Vic 3083, Australia.
| | - Jason J Paxman
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Vic 3083, Australia.
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Royal Parade, Parkville, Vic 3052, Australia.
| | - Begoña Heras
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Vic 3083, Australia.
| |
Collapse
|
36
|
Abstract
Disulfide bonds are important for the stability and function of many secreted proteins. In Gram-negative bacteria, these linkages are catalyzed by thiol-disulfide oxidoreductases (Dsb) in the periplasm. Protein oxidation has been well studied in these organisms, but it has not fully been explored in Gram-positive bacteria, which lack traditional periplasmic compartments. Recent bioinformatics analyses have suggested that the high-GC-content bacteria (i.e., actinobacteria) rely on disulfide-bond-forming pathways. In support of this, Dsb-like proteins have been identified in Mycobacterium tuberculosis, but their functions are not known. Actinomyces oris and Corynebacterium diphtheriae have recently emerged as models to study disulfide bond formation in actinobacteria. In both organisms, disulfide bonds are catalyzed by the membrane-bound oxidoreductase MdbA. Remarkably, unlike known Dsb proteins, MdbA is important for pathogenesis and growth, which makes it a potential target for new antibacterial drugs. This review will discuss disulfide-bond-forming pathways in bacteria, with a special focus on Gram-positive bacteria.
Collapse
|
37
|
McMahon RM, Coinçon M, Tay S, Heras B, Morton CJ, Scanlon MJ, Martin JL. Sent packing: protein engineering generates a new crystal form of Pseudomonas aeruginosa DsbA1 with increased catalytic surface accessibility. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:2386-95. [PMID: 26627647 PMCID: PMC4667283 DOI: 10.1107/s1399004715018519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/03/2015] [Indexed: 11/24/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen for which new antimicrobial drug options are urgently sought. P. aeruginosa disulfide-bond protein A1 (PaDsbA1) plays a pivotal role in catalyzing the oxidative folding of multiple virulence proteins and as such holds great promise as a drug target. As part of a fragment-based lead discovery approach to PaDsbA1 inhibitor development, the identification of a crystal form of PaDsbA1 that was more suitable for fragment-soaking experiments was sought. A previously identified crystallization condition for this protein was unsuitable, as in this crystal form of PaDsbA1 the active-site surface loops are engaged in the crystal packing, occluding access to the target site. A single residue involved in crystal-packing interactions was substituted with an amino acid commonly found at this position in closely related enzymes, and this variant was successfully used to generate a new crystal form of PaDsbA1 in which the active-site surface is more accessible for soaking experiments. The PaDsbA1 variant displays identical redox character and in vitro activity to wild-type PaDsbA1 and is structurally highly similar. Two crystal structures of the PaDsbA1 variant were determined in complex with small molecules bound to the protein active site. These small molecules (MES, glycerol and ethylene glycol) were derived from the crystallization or cryoprotectant solutions and provide a proof of principle that the reported crystal form will be amenable to co-crystallization and soaking with small molecules designed to target the protein active-site surface.
Collapse
Affiliation(s)
- Roisin M. McMahon
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, 306 Carmody Road, Brisbane, Queensland 4072, Australia
| | - Mathieu Coinçon
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, 306 Carmody Road, Brisbane, Queensland 4072, Australia
| | - Stephanie Tay
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, 306 Carmody Road, Brisbane, Queensland 4072, Australia
| | - Begoña Heras
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, 306 Carmody Road, Brisbane, Queensland 4072, Australia
| | - Craig J. Morton
- Biota Holdings Limited, Unit 10, 585 Blackburn Road, Notting Hill, Victoria 3168, Australia
| | - Martin J. Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Jennifer L. Martin
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, 306 Carmody Road, Brisbane, Queensland 4072, Australia
| |
Collapse
|
38
|
Abstract
Antibacterial drugs with novel scaffolds and new mechanisms of action are desperately needed to address the growing problem of antibiotic resistance. The periplasmic oxidative folding system in Gram-negative bacteria represents a possible target for anti-virulence antibacterials. By targeting virulence rather than viability, development of resistance and side effects (through killing host native microbiota) might be minimized. Here, we undertook the design of peptidomimetic inhibitors targeting the interaction between the two key enzymes of oxidative folding, DsbA and DsbB, with the ultimate goal of preventing virulence factor assembly. Structures of DsbB - or peptides - complexed with DsbA revealed key interactions with the DsbA active site cysteine, and with a hydrophobic groove adjacent to the active site. The present work aimed to discover peptidomimetics that target the hydrophobic groove to generate non-covalent DsbA inhibitors. The previously reported structure of a Proteus mirabilis DsbA active site cysteine mutant, in a non-covalent complex with the heptapeptide PWATCDS, was used as an in silico template for virtual screening of a peptidomimetic fragment library. The highest scoring fragment compound and nine derivatives were synthesized and evaluated for DsbA binding and inhibition. These experiments discovered peptidomimetic fragments with inhibitory activity at millimolar concentrations. Although only weakly potent relative to larger covalent peptide inhibitors that interact through the active site cysteine, these fragments offer new opportunities as templates to build non-covalent inhibitors. The results suggest that non-covalent peptidomimetics may need to interact with sites beyond the hydrophobic groove in order to produce potent DsbA inhibitors.
Collapse
|