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1.
Chem Sci ; 2024 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-39144457

RESUMO

The sensitive, rapid and accurate diagnosis of Mycobacterium tuberculosis (Mtb) infection is a central challenge in controlling the global tuberculosis (TB) pandemic. Yet the detection of mycobacteria is often made difficult by the low sensitivity of current diagnostic tools, with over 3.6 million TB cases missed each year. To overcome these limitations there is an urgent need for next-generation TB diagnostic technologies. Here we report the use of a discrete panel of native 19F-trehalose (F-Tre) analogues to label and directly visualise Mtb by exploiting the uptake of fluorine-modified trehalose analogues via the mycobacterial trehalose LpqY-SugABC ATP-binding cassette (ABC) importer. We discovered the extent of modified F-Tre uptake correlates with LpqY substrate recognition and characterisation of the interacting sites by saturation transfer difference NMR coupled with molecular dynamics provides a unique glimpse into the molecular basis of fluorine-modified trehalose import in Mtb. Lipid profiling demonstrated that F-Tre analogues modified at positions 2, 3 and 6 are incorporated into mycobacterial cell-surface trehalose-containing glycolipids. This rapid one-step labelling approach facilitates the direct visualisation of F-Tre-labelled Mtb by Focused Ion Beam (FIB) Secondary Ion Mass Spectrometry (SIMS), enabling detection of the Mtb pathogen. Collectively, our findings highlight that F-Tre analogues have potential as tools to probe and unravel Mtb biology and can be exploited to detect and image TB.

2.
RSC Med Chem ; 13(10): 1225-1233, 2022 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-36320433

RESUMO

Tuberculosis, caused by Mycobacterium tuberculosis, claims ∼1.5 million lives annually. Effective chemotherapy is essential to control TB, however the emergence of drug-resistant strains of TB have seriously threatened global attempts to control and eradicate this deadly pathogen. Trehalose recycling via the LpqY-SugABC importer is essential for the virulence and survival of Mtb and inhibiting or hijacking this transport system is an attractive approach for the development of novel anti-tubercular and diagnostic agents. Therefore, we interrogated the drug-like compounds in the open-source Medicines for Malaria Pathogen Box and successfully identified seven compounds from the TB, kinetoplastids and reference compound disease sets that recognise LpqY. The molecules have diverse chemical scaffolds, are not specific trehalose analogues, and may be used as novel templates to facilitate the development of therapeutics that kill Mtb with a novel mechanism of action via the mycobacterial trehalose LpqY-SugABC transport system.

3.
Chem Commun (Camb) ; 58(67): 9361-9364, 2022 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-35917119

RESUMO

Dimeric boronic acids kill Mycobacterium tuberculosis (Mtb) by targeting mycobacterial specific extracellular glycans, removing the requirement for a therapeutic agent to permeate the complex cell envelope. Here we report the successful development and use of new 'clickable' boronic acid probes as a powerful method to enable the direct detection and visualisation of this unique class of cell-surface targeting antitubercular agents.


Assuntos
Ácidos Borônicos , Mycobacterium tuberculosis , Antituberculosos/metabolismo , Antituberculosos/farmacologia , Ácidos Borônicos/metabolismo , Ácidos Borônicos/farmacologia , Polímeros/metabolismo , Polissacarídeos/metabolismo
4.
ACS Macro Lett ; 11(3): 317-322, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-35575357

RESUMO

The COVID-19 pandemic has highlighted the need for innovative biosensing, diagnostic, and surveillance platforms. Here we report that glycosylated, polymer-stabilized, gold nanorods can bind the SARS-CoV-2 spike protein and show correlation to the presence of SARS-CoV-2 in primary COVID-19 clinical samples. Telechelic polymers were prepared by reversible addition-fragmentation chain-transfer polymerization, enabling the capture of 2,3-sialyllactose and immobilization onto gold nanorods. Control experiments with a panel of lectins and a galactosamine-terminated polymer confirmed the selective binding. The glycosylated rods were shown to give dose-dependent responses against recombinant truncated SARS-CoV-2 spike protein, and the responses were further correlated using primary patient swab samples. The essentiality of the anisotropic particles for reducing the background interference is demonstrated. This highlights the utility of polymer tethering of glycans for plasmonic biosensors of infection.


Assuntos
COVID-19 , Nanotubos , COVID-19/diagnóstico , Ouro , Humanos , Pandemias , Polímeros , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus/metabolismo
5.
ACS Sens ; 6(10): 3696-3705, 2021 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-34634204

RESUMO

The COVID-19 pandemic, and future pandemics, require diagnostic tools to track disease spread and guide the isolation of (a)symptomatic individuals. Lateral-flow diagnostics (LFDs) are rapid and of lower cost than molecular (genetic) tests, with current LFDs using antibodies as their recognition units. Herein, we develop a prototype flow-through device (related, but distinct to LFDs), utilizing N-acetyl neuraminic acid-functionalized, polymer-coated, gold nanoparticles as the detection/capture unit for SARS-COV-2, by targeting the sialic acid-binding site of the spike protein. The prototype device can give rapid results, with higher viral loads being faster than lower viral loads. The prototype's effectiveness is demonstrated using spike protein, lentiviral models, and a panel of heat-inactivated primary patient nasal swabs. The device was also shown to retain detection capability toward recombinant spike proteins from several variants (mutants) of concern. This study provides the proof of principle that glyco-lateral-flow devices could be developed to be used in the tracking monitoring of infectious agents, to complement, or as alternatives to antibody-based systems.


Assuntos
COVID-19 , Nanopartículas Metálicas , Ouro , Humanos , Pandemias , Polissacarídeos , SARS-CoV-2
6.
Metallomics ; 13(4)2021 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-33693931

RESUMO

The treatment of tuberculosis (TB) poses a major challenge as frontline therapeutic agents become increasingly ineffective with the emergence and spread of drug-resistant strains of Mycobacterium tuberculosis (Mtb). To combat this global health problem, new antitubercular agents with novel modes of action are needed. We have screened a close family of 17 organometallic half-sandwich Os(II) complexes [(arene)Os(phenyl-azo/imino-pyridine)(Cl/I)]+Y- containing various arenes (p-cymene, biphenyl, or terphenyl), and NMe2, F, Cl, or Br phenyl or pyridyl substituents, for activity towards Mtb in comparison with normal human lung cells (MRC5). In general, complexes with a monodentate iodido ligand were more potent than chlorido complexes, and the five most potent iodido complexes (MIC 1.25-2.5 µM) have an electron-donating Me2N or OH substituent on the phenyl ring. As expected, the counter anion Y (PF6-, Cl-, I-) had little effect on the activity. The pattern of potency of the complexes towards Mtb is similar to that towards human cells, perhaps because in both cases intracellular thiols are likely to be involved in their activation and their redox mechanism of action. The most active complex against Mtb is the p-cymene Os(II) NMe2-phenyl-azopyridine iodido complex (2), a relatively inert complex that also exhibits potent activity towards cancer cells. The uptake of Os from complex 2 by Mtb is rapid and peaks after 6 h, with temperature-dependence studies suggesting a major role for active transport. Significance to Metallomics Antimicrobial resistance is a global health problem. New advances are urgently needed in the discovery of new antibiotics with novel mechanisms of action. Half-sandwich organometallic complexes offer a versatile platform for drug design. We show that with an appropriate choice of the arene, an N,N-chelated ligand, and monodentate ligand, half-sandwich organo-osmium(II) complexes can exhibit potent activity towards Mycobacterium tuberculosis (Mtb), the leading cause of death from a single infectious agent. The patterns of activity of the 17 azo- and imino-pyridine complexes studied here towards Mtb and normal lung cells suggest a common redox mechanism of action involving intracellular thiols.


Assuntos
Antineoplásicos/farmacologia , Antituberculosos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Compostos Organometálicos/farmacologia , Osmio/química , Tuberculose/tratamento farmacológico , Antineoplásicos/química , Antituberculosos/química , Proliferação de Células , Humanos , Estrutura Molecular , Mycobacterium tuberculosis/crescimento & desenvolvimento , Compostos Organometálicos/química , Tuberculose/microbiologia , Células Tumorais Cultivadas
7.
J Biol Chem ; 296: 100307, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33476646

RESUMO

The Mycobacterium tuberculosis (Mtb) LpqY-SugABC ATP-binding cassette transporter is a recycling system that imports trehalose released during remodeling of the Mtb cell-envelope. As this process is essential for the virulence of the Mtb pathogen, it may represent an important target for tuberculosis drug and diagnostic development, but the transporter specificity and molecular determinants of substrate recognition are unknown. To address this, we have determined the structural and biochemical basis of how mycobacteria transport trehalose using a combination of crystallography, saturation transfer difference NMR, molecular dynamics, site-directed mutagenesis, biochemical/biophysical assays, and the synthesis of trehalose analogs. This analysis pinpoints key residues of the LpqY substrate binding lipoprotein that dictate substrate-specific recognition and has revealed which disaccharide modifications are tolerated. These findings provide critical insights into how the essential Mtb LpqY-SugABC transporter reuses trehalose and modified analogs and specifies a framework that can be exploited for the design of new antitubercular agents and/or diagnostic tools.


Assuntos
Transportadores de Cassetes de Ligação de ATP/química , Proteínas de Bactérias/química , Mycobacterium tuberculosis/metabolismo , Mycobacterium tuberculosis/patogenicidade , Trealose/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Substituição de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Transporte Biológico , Parede Celular/genética , Parede Celular/metabolismo , Clonagem Molecular , Cristalografia por Raios X , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Ligantes , Simulação de Dinâmica Molecular , Mutação , Mycobacterium tuberculosis/genética , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Termodinâmica , Trealose/análogos & derivados , Virulência
8.
ACS Cent Sci ; 6(11): 2046-2052, 2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-33269329

RESUMO

There is an urgent need to understand the behavior of the novel coronavirus (SARS-COV-2), which is the causative agent of COVID-19, and to develop point-of-care diagnostics. Here, a glyconanoparticle platform is used to discover that N-acetyl neuraminic acid has affinity toward the SARS-COV-2 spike glycoprotein, demonstrating its glycan-binding function. Optimization of the particle size and coating enabled detection of the spike glycoprotein in lateral flow and showed selectivity over the SARS-COV-1 spike protein. Using a virus-like particle and a pseudotyped lentivirus model, paper-based lateral flow detection was demonstrated in under 30 min, showing the potential of this system as a low-cost detection platform.

9.
Org Biomol Chem ; 18(18): 3607-3612, 2020 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-32350493

RESUMO

The uptake and metabolism of the disaccharide trehalose by Mycobacterium tuberculosis is essential for the virulence of this pathogen. Here we describe the chemoenzymatic synthesis of new azido-functionalised asymmetric trehalose probes that resist degradation by mycobacterial enzymes and are used to probe trehalose processing pathways in mycobacteria.


Assuntos
Dissacarídeos/metabolismo , Mycobacterium tuberculosis/química , Trealose/metabolismo , Configuração de Carboidratos , Dissacarídeos/análise , Microscopia de Fluorescência , Mycobacterium tuberculosis/metabolismo , Trealose/análogos & derivados , Trealose/química
10.
Org Biomol Chem ; 17(43): 9524-9528, 2019 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-31659363

RESUMO

Dimeric benzoboroxoles that are covalently linked by a short scaffold enhance selective anti-tubercular activity. These multimeric benzoboroxole compounds are capable of engaging the specific extracellular Mycobacterium tuberculosis glycans, do not lead to the evolution of resistance and bypass the need to cross the impermeable mycobacterial cell envelope barrier.


Assuntos
Antituberculosos/farmacologia , Ácidos Borônicos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Células A549 , Antituberculosos/síntese química , Antituberculosos/química , Ácidos Borônicos/síntese química , Ácidos Borônicos/química , Dimerização , Eritrócitos , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular
11.
ACS Chem Biol ; 14(9): 1879-1887, 2019 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-31433162

RESUMO

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB) and has evolved an incredible ability to survive latently within the human host for decades. The Mtb pathogen encodes for a low number of ATP-binding cassette (ABC) importers for the acquisition of carbohydrates that may reflect the nutrient poor environment within the host macrophages. Mtb UgpB (Rv2833c) is the substrate binding domain of the UgpABCE transporter that recognizes glycerophosphocholine (GPC), indicating that this transporter has a role in recycling glycerophospholipid metabolites. By using a combination of saturation transfer difference (STD) NMR and X-ray crystallography, we report the structural analysis of Mtb UgpB complexed with GPC and have identified that Mtb UgpB not only recognizes GPC but is also promiscuous for a broad range of glycerophosphodiesters. Complementary biochemical analyses and site-directed mutagenesis precisely define the molecular basis and specificity of glycerophosphodiester recognition. Our results provide critical insights into the structural and functional role of the Mtb UgpB transporter and reveal that the specificity of this ABC-transporter is not limited to GPC, therefore optimizing the ability of Mtb to scavenge scarce nutrients and essential glycerophospholipid metabolites via a single transporter during intracellular infection.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteínas de Bactérias/metabolismo , Glicerilfosforilcolina/metabolismo , Mycobacterium tuberculosis/química , Transportadores de Cassetes de Ligação de ATP/química , Proteínas de Bactérias/química , Sítios de Ligação , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Escherichia coli/química , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Ligação Proteica , Domínios Proteicos , Especificidade por Substrato
12.
Chem Sci ; 10(23): 5935-5942, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31360399

RESUMO

Innovative chemotherapeutic agents that are active against Mycobacterium tuberculosis (Mtb) are urgently required to control the tuberculosis (TB) epidemic. The Mtb cell envelope has distinct (lipo)polysaccharides and glycolipids that play a critical role in Mtb survival and pathogenesis and disruption of pathways involved in the assembly of the Mtb cell envelope are the primary target of anti-tubercular agents. Here we introduce a previously unexplored approach whereby chemical agents directly target the extracellular glycans within the unique Mtb cell envelope, rather than the intracellular biosynthetic machinery. We designed and synthesised multimeric boronic acids that are selectively lethal to Mtb and function by targeting these structurally unique and essential Mtb cell envelope glycans. By tuning the number of, and distance between, boronic acid units high selectivity to Mtb, low cytotoxicity against mammalian cells and no observable resistance was achieved. This non-conventional approach may prevent the development of drug-resistance and will act as a platform for the design of improved, pathogen-specific, next generation antibiotics.

13.
J Biol Chem ; 293(25): 9770-9783, 2018 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-29728457

RESUMO

The Mycobacterium tuberculosis (Mtb) pathogen encodes a GlcNAc-6-phosphate deacetylase enzyme, NagA (Rv3332), that belongs to the amidohydrolase superfamily. NagA enzymes catalyze the deacetylation of GlcNAc-6-phosphate (GlcNAc6P) to glucosamine-6-phosphate (GlcN6P). NagA is a potential antitubercular drug target because it represents the key enzymatic step in the generation of essential amino-sugar precursors required for Mtb cell wall biosynthesis and also influences recycling of cell wall peptidoglycan fragments. Here, we report the structural and functional characterization of NagA from Mycobacterium smegmatis (MSNagA) and Mycobacterium marinum (MMNagA), close relatives of Mtb Using a combination of X-ray crystallography, site-directed mutagenesis, and biochemical and biophysical assays, we show that these mycobacterial NagA enzymes are selective for GlcNAc6P. Site-directed mutagenesis studies revealed crucial roles of conserved residues in the active site that underpin stereoselective recognition, binding, and catalysis of substrates. Moreover, we report the crystal structure of MSNagA in both ligand-free form and in complex with the GlcNAc6P substrate at 2.6 and 2.0 Å resolutions, respectively. The GlcNAc6P complex structure disclosed the precise mode of GlcNAc6P binding and the structural framework of the active site, including two divalent metals located in the α/ß binuclear site. Furthermore, we observed a cysteine residue located on a flexible loop region that occludes the active site. This cysteine is unique to mycobacteria and may represent a unique subsite for targeting mycobacterial NagA enzymes. Our results provide critical insights into the structural and mechanistic properties of mycobacterial NagA enzymes having an essential role in amino-sugar and nucleotide metabolism in mycobacteria.


Assuntos
Acetilglucosamina/análogos & derivados , Amidoidrolases/química , Amidoidrolases/metabolismo , Mycobacterium tuberculosis/enzimologia , Acetilglucosamina/química , Acetilglucosamina/metabolismo , Amidoidrolases/genética , Domínio Catalítico , Cristalografia por Raios X , Metais/metabolismo , Modelos Moleculares , Mutagênese Sítio-Dirigida , Mutação , Conformação Proteica
14.
Br J Pharmacol ; 174(14): 2183-2193, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28195652

RESUMO

BACKGROUND AND PURPOSE: Tuberculosis (TB) remains a major global health threat and is now the leading cause of death from a single infectious agent worldwide. The current TB drug regimen is inadequate, and new anti-tubercular agents are urgently required to be able to successfully combat the increasing prevalence of drug-resistant TB. The purpose of this study was to investigate a piperidinol compound derivative that is highly active against the Mycobacterium tuberculosis bacillus. EXPERIMENTAL APPROACH: The antibacterial properties of the piperidinol compound and its corresponding bis-Mannich base analogue were evaluated against M. smegmatis and Gram-negative organisms. Cytotoxicity studies were undertaken in order to determine the selectivity index for these compounds. Spontaneous resistant mutants of M. smegmatis were generated against the piperidinol and corresponding bis-Mannich base lead derivatives and whole genome sequencing employed to determine the genetic modifications that lead to selection pressure in the presence of these compounds. KEY RESULTS: The piperidinol and the bis-Mannich base analogue were found to be selective for mycobacteria and rapidly kill this organism with a cytotoxicity selectivity index for mycobacteria of >30-fold. Whole genome sequencing of M. smegmatis strains resistant to the lead compounds led to the identification of a number of single nucleotide polymorphisms indicating multiple targets. CONCLUSION AND IMPLICATIONS: Our results indicate that the piperidinol moiety represents an attractive compound class in the pursuit of novel anti-tubercular agents. LINKED ARTICLES: This article is part of a themed section on Drug Metabolism and Antibiotic Resistance in Micro-organisms. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.14/issuetoc.


Assuntos
Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Mycobacterium smegmatis/efeitos dos fármacos , Piperidinas/farmacologia , Pseudomonas putida/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mycobacterium smegmatis/genética , Piperidinas/síntese química , Piperidinas/química , Polimorfismo de Nucleotídeo Único/efeitos dos fármacos , Polimorfismo de Nucleotídeo Único/genética , Relação Estrutura-Atividade , Células Tumorais Cultivadas
15.
J Org Chem ; 81(13): 5547-65, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27267662

RESUMO

The barrier to rotation around the N-alkenyl bond of 38 N-alkenyl-N-alkylacetamide derivatives was measured (ΔG(⧧) rotation varied between <8.0 and 31.0 kcal mol(-1)). The most important factor in controlling the rate of rotation was the level of alkene substitution, followed by the size of the nitrogen substituent and, finally, the size of the acyl substituent. Tertiary enamides with four alkenyl substituents exhibited half-lives for rotation between 5.5 days and 99 years at 298 K, sufficient to isolate enantiomerically enriched atropisomers. The radical cyclizations of a subset of N-alkenyl-N-benzyl-α-haloacetamides exhibiting relatively high barriers to rotation round the N-alkenyl bond (ΔG(⧧) rotation >20 kcal mol(-1)) were studied to determine the regiochemistry of cyclization. Those with high barriers (>27 kcal mol(-1)) did not lead to cyclization, but those with lower values produced highly functionalized γ-lactams via a 5-endo-trig radical-polar crossover process that was terminated by reduction, an unusual cyclopropanation sequence, or trapping with H2O, depending upon the reaction conditions. Because elevated temperatures were necessary for cyclization, this precluded study of the asymmetric transfer in the reaction of individual atropisomers. However, enantiomerically enriched atropsiomeric enamides should be regarded as potential asymmetric building blocks for reactions that can be accomplished at room temperature.

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