Rationally Designed Nucleoside Antibiotics That Inhibit Siderophore Biosynthesis of Mycobacterium tuberculosis

Somu, Ravindranadh V.; Boshoff, Helena I.; Qiao, Chunhua; Bennett, Eric M.; Barry, Clifton E.; Aldrich, Courtney C.

doi:10.1021/jm051060o

Cited by 223 publications

(283 citation statements)

References 24 publications

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“…A crucial portion of such an inhibitor scaffold is the linker between the amino acid and the adenosine moiety, which needs to be metabolically stable (13). Many different linkers have been developed as surrogates for the natural labile acylphosphate linkage (2,15,18). Aminoacyl-sulfamoyl adenosines were found to be the most potent analogues and proved to be nanomolar inhibitors of their corresponding aaRSs (3,12,16).…”

Section: Resultsmentioning

confidence: 99%

Characterization of Peptide Chain Length and Constituency Requirements for YejABEF-Mediated Uptake of Microcin C Analogues

et al. 2011

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Microcin C (McC), a natural antibacterial compound consisting of a heptapeptide attached to a modified adenosine, is actively taken up by the YejABEF transporter, after which it is processed by cellular aminopeptidases, releasing the nonhydrolyzable aminoacyl adenylate, an inhibitor of aspartyl-tRNA synthetase. McC analogues with variable length of the peptide moiety were synthesized and evaluated in order to characterize the substrate preferences of the YejABEF transporter. It was shown that a minimal peptide chain length of 6 amino acids and the presence of an N-terminal formyl-methionyl-arginyl sequence are required for transport.In the current ongoing quest for new antibiotics, aminoacyltRNA synthetases (aaRSs) have been regarded as promising targets (5,11,14). The natural antibiotic microcin C (McC) (Fig. 1, compound 1a) targets an aaRS and has been envisaged as a lead compound for further development as an antibacterial agent (17). McC consists of a heptapeptide that is covalently linked through a phosphoramidate bond to adenosine, with, in addition, an aminopropyl moiety esterified to the phosphoramidate linker (4). Once inside a sensitive cell, McC is processed by peptide deformylase and several peptidases that remove the N-terminal formyl group and the peptide part, respectively (7). As a result of intracellular processing, the active compound (compound 2), a modified nonhydrolysable aspartyl-adenylate, is released. Processed McC is a potent inhibitor of aspartyl-tRNA synthetase (AspRS) (8).McC penetrates the outer membrane of the Escherichia coli cell mostly through the OmpF porin, but also through other, yet-unidentified transport systems (M. Novikova, A. Metlitskaya, and K. Severinov, unpublished data), and is subsequently transported through the inner membrane by the YejABEF transporter (10). YejABEF is the only complex responsible for McC transport, since yej mutants are highly resistant to McC and its maturation intermediates and chemical analogues. While intact McC inhibits the growth of sensitive E. coli cells at low micromolar concentrations, processed McC does not affect cell growth, even at millimolar concentrations. Thus, the peptide chain enables McC to function through a Trojan-horse mechanism by promoting active uptake via the YejABEF transporter. The recently improved synthetic approach for the production of McC analogues has led us to investigate the uptake properties of the Yej transporter in more detail. The results obtained could be important for further drug development, where peptides function as carrier moieties for drugs that otherwise would not be able to penetrate the bacterial membranes. Here, we used a number of McC analogues truncated either from their C-or N-terminal sides, or otherwise modified, to determine the minimal peptide chain length sufficient for facilitated transport by Yej. MATERIALS AND METHODSChemistry. Reagents and solvents were purchased from commercial suppliers (Acros, Sigma-Aldrich, Bachem, and Novabiochem) and used as provided unless otherwise indicated....

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Section: Resultsmentioning

confidence: 99%

Characterization of Peptide Chain Length and Constituency Requirements for YejABEF-Mediated Uptake of Microcin C Analogues

et al. 2011

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“…Siderophore synthesis has recently been identified as a target for antibiotic development (12,37,38). In these studies, the NRPS adenylation domain has served as the target for inhibitor design.…”

Section: Discussionmentioning

confidence: 99%

“…Finally there are four proteins, PvcABCD, that have been implicated in chromophore maturation (11), although the essential role of these proteins has been questioned (3). Because the enzymes that catalyze siderophore synthesis have been targeted recently for antibiotic development (12), insights into the pyoverdine synthetic pathway may identify new antibiotic targets.…”

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confidence: 99%

The 1.8 Å Crystal Structure of PA2412, an MbtH-like Protein from the Pyoverdine Cluster of Pseudomonas aeruginosa

Drake

Cao

et al. 2007

Journal of Biological Chemistry

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Many bacteria use nonribosomal peptide synthetase (NRPS) proteins to produce peptide antibiotics and siderophores. The catalytic domains of the NRPS proteins are usually linked in large multidomain proteins. Often, additional proteins are coexpressed with NRPS proteins that modify the NRPS peptide products, ensure the availability of substrate building blocks, or play a role in the import or export of the NRPS product. Many NRPS clusters include a small protein of ϳ80 amino acids with homology to the MbtH protein of mycobactin synthesis in Mycobacteria tuberculosis; no function has been assigned to these proteins. Pseudomonas aeruginosa utilizes an NRPS cluster to synthesize the siderophore pyoverdine. The pyoverdine peptide contains a dihydroxyquinoline-based chromophore, as well as two formyl-N-hydroxyornithine residues, which are involved in iron binding. The pyoverdine cluster contains four modular NRPS enzymes and 10 -15 additional proteins that are essential for pyoverdine production. Coexpressed with the pyoverdine synthetic enzymes is a 72-amino acid MbtH-like family member designated PA2412. We have determined the three-dimensional structure of the PA2412 protein and describe here the structure and the location of conserved regions. Additionally, we have further analyzed a deletion mutant of the PA2412 protein for growth and pyoverdine production. Our results demonstrate that PA2412 is necessary for the production or secretion of pyoverdine at normal levels. The PA2412 deletion strain is able to use exogenously produced pyoverdine, showing that there is no defect in the uptake or utilization of the iron-pyoverdine complex.Iron is an essential cofactor for many proteins, playing both catalytic and structural roles (1-3). Because of the low solubility of free Fe 3ϩ , many bacteria produce siderophores that bind to iron. The iron-siderophore complex is then actively transported into the cell. Although some small molecules like citrate or salicylate are able to function as lower affinity siderophores, many specialized peptides with extremely high affinity for iron are produced nonribosomally by bacteria. These compounds are produced by nonribosomal peptide synthetases (NRPSs) 2 that exist as modular proteins with multiple catalytic domains joined in a single protein. Often expressed with NRPS genes are other genes that encode proteins involved in additional essential steps including the synthesis of building blocks, siderophore export, import of the Fe 3ϩ -siderophore complex, or the removal Fe 3ϩ from the imported siderophore (4, 5). Pseudomonas aeruginosa is a bacterial pathogen that commonly causes infections in patients with cystic fibrosis (6). The siderophore pyoverdine (Fig. 1) is synthesized by P. aeruginosa (3) and has been correlated with virulence (7). Pyoverdine contains a cyclic peptide chain as well as a chemically modified dihydroxyquinoline-based chromophore that is responsible for iron binding. The peptide backbone of pyoverdine is synthesized by four large, multi-module NRPS proteins. The ...

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“…90 Os dois principais sideróforos presentes no MTB são: micobactinas e carboximicobactinas. 91 Estudos revelaram que cepas mutantes de MTB com deficiência em micobactina são incapazes de estabelecer infecção em camundongos. 92,93 Esta observação aponta a biossíntese de micobactina como um potencial alvo no MTB.…”

Section: Alvos Envolvidos Com O Metabolismo Do Ferrounclassified

“…Especificamente, o análogo nucleosídeo (34) demonstrou CIM 99 de 0,29 μmol L -1 , similar a isoniazida (0.18 μmol L -1 ) (Figura 12). 91 Entretanto, apesar das características farmacodinâmicas promissoras, a molécula demonstrou características farmacocinéticas inadequadas, como baixa biodisponibilidade e tempo de meia vida reduzido (t 1/2 = 11 min). 94 Estudos adicionais descreveram um inibidor (35) (Figura 12) da enzima MbtA com CIM 99 de 0,78 μmol L -1 contra cepas de MTB H 37 Rv e melhores propriedades farmacocinéticas (t 1/2 = 62 min) que o seu análogo (34).…”

Section: Alvos Envolvidos Com O Metabolismo Do Ferrounclassified

Potenciais alvos moleculares para o desenvolvimento de novos fármacos antituberculose

2017

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POTENTIAL MOLECULAR TARGETS FOR ANTITUBERCULOSIS DRUG DISCOVERY. Tuberculosis (TB) is an infectious disease caused by mycobacteria from the Mycobacterium genus, mainly by Mycobacterium tuberculosis (MTB). The World HealthOrganization (WHO) aims to reduce the number of TB cases worldwide in the coming years. Nevertheless, the increasing number of multidrug-resistant (MDR-TB) and extensive-drug resistance (XDR-TB) strains, and the ineffectiveness of the current treatment in latent tuberculosis are challenges to be overcome. In this review, we will demonstrate the recent advances in the tuberculosis drug discovery, focusing the research of new molecular targets in the Mycobacterium tuberculosis. Among the promising targets described herein, we highlight those, which act in different pathways in the mycobacteria, such as energy metabolism, cell wall biosynthesis, DNA synthesis, iron metabolism and transport through membranes. Furthermore, bioactive compounds discovered using phenotypic assays screening and validated through genetic approaches are also presented.Keywords: medicinal chemistry; tuberculosis; Mycobacterium tuberculosis; molecular targets; new drugs. INTRODUÇÃOA tuberculose (TB) é uma doença infecciosa causada por micobactérias do complexo Mycobacterium, no entanto, a espécie responsável pelo maior número de casos de morbidade e mortalidade é o Mycobacterium tuberculosis (MTB). 1 Ocupando o ranking mundial como a principal causa de mortes causadas por doenças infecciosas, nos últimos anos a tuberculose ultrapassou, em número de casos, a infecção causada pelo vírus da imunodeficiência humana (HIV). 2,3 O último levantamento realizado em 2015 pela Organização Mundial da Saúde (OMS) apontou 9.6 milhões de novos casos no mundo e 1.5 milhões de mortes causadas pela doença. 3 Somado a esses dados, o surgimento e aumento de cepas de M. tuberculosis multirresistente aos fármacos (MDR-TB) e extensivamente resistente aos fármacos (XDR-TB) vêm alarmando as autoridades de todo o mundo. Essas formas de tuberculose apresentam baixas taxas de cura e maiores taxas de mortalidade devido às dificuldades de tratamento. 4 Além disso, já foram relatados na clínica casos de tuberculose totalmente resistente aos fármacos (TDR-TB). 5,6 Ao longo dos últimos anos, é possível constatar algumas evoluções no desenvolvimento de compostos candidatos a fármacos que possam atuar contra a TB. 7 Após um intervalo de mais de 50 anos sem novos medicamentos para o tratamento da TB, a bedaquilina foi aprovada em 2012 pela agência norte-americana U.S. Food and Drug Administration (FDA) para o tratamento de MDR-TB. Atualmente, diversos candidatos a fármacos estão em estudos clínicos, [8][9][10][11][12] 39 Atualmente, diversos métodos e estratégias são utilizados para o desenvolvimento de novos fármacos contra a TB, como por exemplo: 1) abordagens genéticas para identificação de novos alvos; 2) ensaios de triagem em larga escala utilizando a micobactéria como plataforma; 3) ferramentas de biologia estrutural e triagem virtual e; 4) modificações ...

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Rationally Designed Nucleoside Antibiotics That Inhibit Siderophore Biosynthesis of Mycobacterium tuberculosis

Abstract: A rationally designed nucleoside inhibitor of Mycobacterium tuberculosis growth (MIC(99) = 0.19 microM) that disrupts siderophore biosynthesis was identified. The activity is due to inhibition of the adenylate-forming enzyme MbtA which is involved in biosynthesis of the mycobactins.

Cited by 223 publications

References 24 publications

Characterization of Peptide Chain Length and Constituency Requirements for YejABEF-Mediated Uptake of Microcin C Analogues

Characterization of Peptide Chain Length and Constituency Requirements for YejABEF-Mediated Uptake of Microcin C Analogues

The 1.8 Å Crystal Structure of PA2412, an MbtH-like Protein from the Pyoverdine Cluster of Pseudomonas aeruginosa

Potenciais alvos moleculares para o desenvolvimento de novos fármacos antituberculose

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