RESUMO
BACKGROUND: Esterases (EC 3.1.1.X) are enzymes that catalyze the hydrolysis ester bonds. These enzymes have large potential for diverse applications in fine industries, particularly in pharmaceuticals, cosmetics, and bioethanol production. METHODS AND RESULTS: In this study, a gene encoding an esterase from Thermobifida fusca YX (TfEst) was successfully cloned, and its product was overexpressed in Escherichia coli and purified using affinity chromatography. The TfEst kinetic assay revealed catalytic efficiencies of 0.58 s-1 mM-1, 1.09 s-1 mM-1, and 0.062 s-1 mM-1 against p-Nitrophenyl acetate, p-Nitrophenyl butyrate, and 1-naphthyl acetate substrates, respectively. Furthermore, TfEst also exhibited activity in a pH range from 6.0 to 10.0, with maximum activity at pH 8.0. The enzyme demonstrated a half-life of 20 min at 70 °C. Notably, TfEst displayed acetyl xylan esterase activity as evidenced by the acetylated xylan assay. The structural prediction of TfEst using AlphaFold indicated that has an α/ß-hydrolase fold, which is consistent with other esterases. CONCLUSIONS: The enzyme stability over a broad pH range and its activity at elevated temperatures make it an appealing candidate for industrial processes. Overall, TfEst emerges as a promising enzymatic tool with significant implications for the advancement of biotechnology and biofuels industries.
Assuntos
Acetilesterase , Esterases , Thermobifida , Acetilesterase/metabolismo , Acetilesterase/genética , Acetilesterase/química , Concentração de Íons de Hidrogênio , Cinética , Especificidade por Substrato , Thermobifida/enzimologia , Thermobifida/genética , Esterases/metabolismo , Esterases/genética , Esterases/química , Estabilidade Enzimática , Temperatura , Escherichia coli/genética , Escherichia coli/metabolismo , Clonagem Molecular/métodos , Hidrólise , Xilanos/metabolismo , Butiratos/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , NitrofenóisRESUMO
Background Esterases (EC 3.1.1.X) are enzymes that catalyze the hydrolysis ester bonds. These enzymes have large potential for diverse applications in fne industries, particularly in pharmaceuticals, cosmetics, and bioethanol production. Methods and results In this study, a gene encoding an esterase from Thermobifda fusca YX (TfEst) was successfully cloned, and its product was overexpressed in Escherichia coli and purifed using afnity chromatography. The TfEst kinetic assay revealed catalytic efciencies of 0.58 s −1 mM−1, 1.09 s−1 mM−1, and 0.062 s−1 mM−1 against p-Nitrophenyl acetate, p-Nitrophenyl butyrate, and 1-naphthyl acetate substrates, respectively. Furthermore, TfEst also exhibited activity in a pH range from 6.0 to 10.0, with maximum activity at pH 8.0. The enzyme demonstrated a half-life of 20 min at 70 °C. Notably, TfEst displayed acetyl xylan esterase activity as evidenced by the acetylated xylan assay. The structural prediction of TfEst using AlphaFold indicated that has an α/β-hydrolase fold, which is consistent with other esterases. Conclusions The enzyme stability over a broad pH range and its activity at elevated temperatures make it an appealing candidate for industrial processes. Overall, TfEst emerges as a promising enzymatic tool with signifcant implications for the advancement of biotechnology and biofuels industries.
RESUMO
Dihydrofolate reductase (DHFR) is a key enzyme involved in the folate pathway that has been heavily targeted for the development of therapeutics against cancer and bacterial and protozoa infections amongst others. Despite being an essential enzyme for Mycobacterium tuberculosis (Mtb) viability, DHFR remains an underexploited target for tuberculosis (TB) treatment. Herein, we report the preparation and evaluation of a series of compounds against Mtb DHFR (MtbDHFR). The compounds have been designed using a merging strategy of traditional pyrimidine-based antifolates with a previously discovered unique fragment hit against MtbDHFR. In this series, four compounds displayed a high affinity against MtbDHFR, with sub-micromolar affinities. Additionally, we determined the binding mode of six of the best compounds using protein crystallography, which revealed occupation of an underutilised region of the active site.
RESUMO
The coenzyme A (CoA) biosynthesis pathway has attracted attention as a potential target for much-needed novel antimicrobial drugs, including for the treatment of tuberculosis (TB), the lethal disease caused by Mycobacterium tuberculosis (Mtb). Seeking to identify inhibitors of Mtb phosphopantetheine adenylyltransferase (MtbPPAT), the enzyme that catalyses the penultimate step in CoA biosynthesis, we performed a fragment screen. In doing so, we discovered three series of fragments that occupy distinct regions of the MtbPPAT active site, presenting a unique opportunity for fragment linking. Here we show how, guided by X-ray crystal structures, we could link weakly-binding fragments to produce an active site binder with a KD <20â µM and on-target anti-Mtb activity, as demonstrated using CRISPR interference. This study represents a big step toward validating MtbPPAT as a potential drug target and designing a MtbPPAT-targeting anti-TB drug.
Assuntos
Mycobacterium tuberculosis , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Nucleotidiltransferases/metabolismo , Antituberculosos/farmacologiaRESUMO
The coenzyme A (CoA) biosynthesis pathway has attracted attention as a potential target for much-needed novel antimicrobial drugs, including for the treatment of tuberculosis (TB), the lethal disease caused by Mycobacterium tuberculosis (Mtb). Seeking to identify inhibitors of Mtb phosphopantetheine adenylyltransferase (MtbPPAT), the enzyme that catalyses the penultimate step in CoA biosynthesis, we performed a fragment screen. In doing so, we discovered three series of fragments that occupy distinct regions of the MtbPPAT active site, presenting a unique opportunity for fragment linking. Here we show how, guided by X-ray crystal structures, we could link weakly-binding fragments to produce an active site binder with a K D <20â µM and on-target anti-Mtb activity, as demonstrated using CRISPR interference. This study represents a big step toward validating MtbPPAT as a potential drug target and designing a MtbPPAT-targeting anti-TB drug.
RESUMO
A key step in the biosynthesis of numerous polyketides is the stereospecific formation of a spiroacetal (spiroketal). We report here that spiroacetal formation in the biosynthesis of the macrocyclic polyketides ossamycin and oligomycin involves catalysis by a novel spiroacetal cyclase. OssO from the ossamycin biosynthetic gene cluster (BGC) is homologous to OlmO, the product of an unannotated gene from the oligomycin BGC. The deletion of olmO abolished oligomycin production and led to the isolation of oligomycin-like metabolites lacking the spiroacetal structure. Purified OlmO catalyzed complete conversion of the major metabolite into oligomycin C. Crystal structures of OssO and OlmO reveal an unusual 10-strand ß-barrel. Three conserved polar residues are clustered together in the ß-barrel cavity, and site-specific mutation of any of these residues either abolished or substantially diminished OlmO activity, supporting a role for general acid/general base catalysis in spiroacetal formation.
Assuntos
Policetídeos , Antibacterianos , Catálise , Família Multigênica , Oligomicinas , Policetídeos/química , Metabolismo SecundárioRESUMO
Glutathione peroxidases (GPx) are a family of enzymes with the ability to reduce organic and inorganic hydroperoxides to the corresponding alcohols using glutathione or thioredoxin as an electron donor. Here, we report the functional and structural characterization of a GPx identified in Trichoderma reesei (TrGPx). TrGPx was recombinantly expressed in a bacterial host and purified using affinity. Using a thioredoxin coupled assay, TrGPx exhibited activity of 28 U and 12.5 U in the presence of the substrates H2O2 and t-BOOH, respectively, and no activity was observed when glutathione was used. These results indicated that TrGPx is a thioredoxin peroxidase and hydrolyses H2O2 better than t-BOOH. TrGPx kinetic parameters using a pyrogallol assay resulted at Kmapp = 11.7 mM, Vmaxapp = 10.9 IU/µg TrGPx, kcat = 19 s-1 and a catalytic efficiency of 1.6 mM-1 s-1 to H2O2 as substrate. Besides that, TrGPx demonstrated an optimum pH ranging from 9.0-12.0 and a half-life of 36 min at 80 °C. TrGPx 3D-structure was obtained in a reduced state and non-catalytic conformation. The overall fold is similar to the other phospholipid-hydroperoxide glutathione peroxidases. These data contribute to understand the antioxidant mechanism in fungi and provide information for using antioxidant enzymes in biotechnological applications.
Assuntos
Hypocreales/enzimologia , Peroxirredoxinas/química , Peroxirredoxinas/metabolismo , Sequência de Aminoácidos , Antioxidantes/química , Antioxidantes/farmacologia , Fracionamento Químico , Clonagem Molecular , Ativação Enzimática , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Expressão Gênica , Glutationa Peroxidase/química , Glutationa Peroxidase/genética , Glutationa Peroxidase/metabolismo , Concentração de Íons de Hidrogênio , Hypocreales/genética , Modelos Moleculares , Peroxirredoxinas/genética , Peroxirredoxinas/isolamento & purificação , Conformação Proteica , Relação Estrutura-Atividade , TemperaturaRESUMO
Glutathione peroxidases (GPx) are a family of enzymes with the ability to reduce organic and inorganic hydroperoxides to the corresponding alcohols using glutathione or thioredoxin as an electron donor. Here, we report the functional and structural characterization of a GPx identified in Trichoderma reesei (TrGPx). TrGPx was recombinantly expressed in a bacterial host and purified using affinity. Using a thioredoxin coupled assay, TrGPx exhibited activity of 28 U and 12.5 U in the presence of the substrates H2O2 and t-BOOH, respectively, and no activity was observed when glutathione was used. These results indicated that TrGPx is a thioredoxin peroxidase and hydrolyses H2O2 better than t-BOOH. TrGPx kinetic parameters using a pyrogallol assay resulted at Kmapp = 11.7 mM, Vmaxapp = 10.9 IU/μg TrGPx, kcat = 19 s−1 and a catalytic efficiency of 1.6 mM−1 s−1 to H2O2 as substrate. Besides that, TrGPx demonstrated an optimum pH ranging from 9.0–12.0 and a half-life of 36 min at 80 °C. TrGPx 3D-structure was obtained in a reduced state and non-catalytic conformation. The overall fold is similar to the other phospholipid-hydroperoxide glutathione peroxidases. These data contribute to understand the antioxidant mechanism in fungi and provide information for using antioxidant enzymes in biotechnological applications.
RESUMO
Adenylate-forming enzymes (AFEs) are a mechanistic superfamily of proteins that are involved in many cellular roles. In the biosynthesis of benzoxazole antibiotics, an AFE has been reported to play a key role in the condensation of cyclic molecules. In the biosynthetic gene cluster for the benzoxazole AJI9561, AjiA1 catalyzes the condensation of two 3-hydroxyanthranilic acid (3-HAA) molecules using ATP as a co-substrate. Here, the enzymatic activity of AjiA1 is reported together with a structural analysis of its apo form. The structure of AjiA1 was solved at 2.0â Å resolution and shows a conserved fold with other AFE family members. AjiA1 exhibits activity in the presence of 3-HAA (Km = 77.86 ± 28.36, kcat = 0.04 ± 0.004) and also with the alternative substrate 3-hydroxybenzoic acid (3-HBA; Km = 22.12 ± 31.35, kcat = 0.08 ± 0.005). The structure of AjiA1 in the apo form also reveals crucial conformational changes that occur during the catalytic cycle of this enzyme which have not been described for any other AFE member. Consequently, the results shown here provide insights into this protein family and a new subgroup is proposed for enzymes that are involved in benzoxazole-ring formation.
Assuntos
Modelos Moleculares , Conformação Proteica , Sítios de Ligação , Domínio Catalítico , Cristalografia por Raios X/métodos , Especificidade por SubstratoRESUMO
Dihydrofolate reductase (DHFR), a key enzyme involved in folate metabolism, is a widely explored target in the treatment of cancer, immune diseases, bacteria, and protozoa infections. Although several antifolates have proved successful in the treatment of infectious diseases, they have been underexplored to combat tuberculosis, despite the essentiality of M. tuberculosis DHFR (MtDHFR). Herein, we describe an integrated fragment-based drug discovery approach to target MtDHFR that has identified hits with scaffolds not yet explored in any previous drug design campaign for this enzyme. The application of a SAR by catalog strategy of an in house library for one of the identified fragments has led to a series of molecules that bind to MtDHFR with low micromolar affinities. Crystal structures of MtDHFR in complex with compounds of this series demonstrated a novel binding mode that considerably differs from other DHFR antifolates, thus opening perspectives for the development of relevant MtDHFR inhibitors.
Assuntos
Antagonistas do Ácido Fólico , Mycobacterium tuberculosis , Tuberculose , Desenho de Fármacos , Antagonistas do Ácido Fólico/farmacologia , Humanos , Tetra-Hidrofolato Desidrogenase/genética , Tuberculose/tratamento farmacológicoRESUMO
Trehalose is an essential disaccharide for mycobacteria and a key constituent of several cell wall glycolipids with fundamental roles in pathogenesis. Mycobacteria possess two pathways for trehalose biosynthesis. However, only the OtsAB pathway was found to be essential in Mycobacterium tuberculosis, with marked growth and virulence defects of OtsA mutants and strict essentiality of OtsB2. Here, we report the first mycobacterial OtsA structures from Mycobacterium thermoresistibile in both apo and ligand-bound forms. Structural information reveals three key residues in the mechanism of substrate preference that were further confirmed by site-directed mutagenesis. Additionally, we identify 2-oxoglutarate and 2-phosphoglycerate as allosteric regulators of OtsA. The structural analysis in this work strongly contributed to define the mechanisms for feedback inhibition, show different conformational states of the enzyme, and map a new allosteric site.IMPORTANCE Mycobacterial infections are a significant source of mortality worldwide, causing millions of deaths annually. Trehalose is a multipurpose disaccharide that plays a fundamental structural role in these organisms as a component of mycolic acids, a molecular hallmark of the cell envelope of mycobacteria. Here, we describe the first mycobacterial OtsA structures. We show mechanisms of substrate preference and show that OtsA is regulated allosterically by 2-oxoglutarate and 2-phosphoglycerate at an interfacial site. These results identify a new allosteric site and provide insight on the regulation of trehalose synthesis through the OtsAB pathway in mycobacteria.
Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Glucosiltransferases/química , Glucosiltransferases/metabolismo , Ácidos Glicéricos/metabolismo , Ácidos Cetoglutáricos/metabolismo , Mycobacteriaceae/enzimologia , Regulação Alostérica , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Glucosiltransferases/genética , Mycobacteriaceae/genética , Mycobacteriaceae/metabolismo , Especificidade por Substrato , Trealose/metabolismoRESUMO
CoaBC, part of the vital coenzyme A biosynthetic pathway in bacteria, has recently been validated as a promising antimicrobial target. In this work, we employed native ion mobility-mass spectrometry to gain structural insights into the phosphopantothenoylcysteine synthetase domain of E. coli CoaBC. Moreover, native mass spectrometry was validated as a screening tool to identify novel inhibitors of this enzyme, highlighting the utility and versatility of this technique both for structural biology and for drug discovery.
Assuntos
Carboxiliases/química , Avaliação Pré-Clínica de Medicamentos/métodos , Proteínas de Escherichia coli/química , Escherichia coli/enzimologia , Espectrometria de Massas/métodos , Complexos Multienzimáticos/química , Peptídeo Sintases/química , Carboxiliases/antagonistas & inibidores , Carboxiliases/metabolismo , Dimerização , Inibidores Enzimáticos/química , Escherichia coli/química , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Proteínas de Escherichia coli/antagonistas & inibidores , Proteínas de Escherichia coli/metabolismo , Cinética , Complexos Multienzimáticos/antagonistas & inibidores , Complexos Multienzimáticos/metabolismo , Peptídeo Sintases/antagonistas & inibidores , Peptídeo Sintases/metabolismo , Domínios ProteicosRESUMO
Epoxide hydrolases (EHs) are enzymes that have high biotechnological interest for the fine and transformation industry. Several of these enzymes have enantioselectivity, which allows their application in the separation of enantiomeric mixtures of epoxide substrates. Although two different families of EHs have been described, those that have the α/ß-hidrolase fold are the most explored for biotechnological purpose. These enzymes are functionally very well studied, but only few members have three-dimensional structures characterised. Recently, a new EH from the filamentous fungi Trichoderma reseei (TrEH) has been discovered and functionally studied. This enzyme does not have high homology to any other EH structure and have an enatiopreference for (S)-(-) isomers. Herein we described the crystallographic structure of TrEH at 1.7Å resolution, which reveals features of its tertiary structure and active site. TrEH has a similar fold to the other soluble epoxide hydrolases and has the two characteristic hydrolase and cap domains. The enzyme is predominantly monomeric in solution and has also been crystallised as a monomer in the asymmetric unit. Although the catalytic residues are conserved, several other residues of the catalytic groove are not, and might be involved in the specificity for substrates and in the enantioselectivy of this enzyme. In addition, the determination of the crystallographic structure of TrEH might contribute to the rational site direct mutagenesis to generate an even more stable enzyme with higher efficiency to be used in biotechnological purposes.
Assuntos
Epóxido Hidrolases/química , Epóxido Hidrolases/metabolismo , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Trichoderma/metabolismo , Domínio Catalítico/fisiologia , Cristalografia por Raios X/métodos , Modelos Moleculares , Mutagênese Sítio-Dirigida/métodosRESUMO
Glycopeptides are an important class of antibiotics used in the treatment of several infections, including those caused by methicillin resistant Staphylococcus aureus. Glycopeptides are biosynthesized by a Non Ribosomal Peptide Synthase (NRPS) and the resulting peptide precursors are decorated by several tailoring enzymes, such as halogenases and glycosyltransferases. These enzymes are important targets of protein engineering to produce new derivatives of known antibiotics. Herein we show the production of two putative halogenases, denominated StaI and StaK, involved in the biosynthesis of the glycopeptide A47,934 in Streptomyces toyocaensis NRRL 15,009. This antibiotic together with the compound UK-68,597 are the unique glycopeptides which have two putative halogenases identified in their gene clusters and three chloride substituent atoms attached to their aglycones. StaI and StaK were successfully produced in E. coli in the soluble fraction with high purity using the wild type gene for StaI and a synthetic codon optimized gene for StaK. We have purified both enzymes by two chromatographic steps and a good yield was obtained. These putative halogenases were co-purified with the co-factor FAD, which are differently reduced by the enzyme SsuE in vitro. We have further confirmed that these putative halogenases are monomeric using a calibrated gel filtration column and through circular dichroism, we confirmed that both enzymes are folded with a predominance of α-helices. Molecular models for StaI and StaK were generated and together with sequence and phylogenetic analysis, we could infer some structural insights of StaI and StaK from the biosynthesis of compound A47,934.
Assuntos
Proteínas de Bactérias , Clonagem Molecular , Expressão Gênica , Glicoproteínas , Família Multigênica , Streptomyces/genética , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Glicoproteínas/biossíntese , Glicoproteínas/química , Glicoproteínas/genética , Glicoproteínas/isolamento & purificação , Estrutura Secundária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Streptomyces/enzimologiaRESUMO
Tetrahydropyran rings are a common feature of complex polyketide natural products, but much remains to be learned about the enzymology of their formation. The enzyme SalBIII from the salinomycin biosynthetic pathway resembles other polyether epoxide hydrolases/cyclases of the MonB family, but SalBIII plays no role in the conventional cascade of ring opening/closing. Mutation in the salBIII gene gave a metabolite in which ringâ A is not formed. Using this metabolite inâ vitro as a substrate analogue, SalBIII has been shown to form pyran ringâ A. We have determined the X-ray crystal structure of SalBIII, and structure-guided mutagenesis of putative active-site residues has identified Asp38 and Asp104 as an essential catalytic dyad. The demonstrated pyran synthase activity of SalBIII further extends the impressive catalytic versatility of α+ß barrel fold proteins.
Assuntos
Policetídeo Sintases/metabolismo , Piranos/metabolismo , Modelos Moleculares , Conformação Molecular , Policetídeo Sintases/química , Policetídeo Sintases/genética , Piranos/química , Streptomyces/enzimologiaRESUMO
Hypoxia-inducible transcription factors (HIF) form heterodimeric complexes that mediate cell responses to hypoxia. The oxygen-dependent stability and activity of the HIF-α subunits is traditionally associated to post-translational modifications such as hydroxylation, acetylation, ubiquitination, and phosphorylation. Here we report novel evidence showing that unsaturated fatty acids are naturally occurring, non-covalent structural ligands of HIF-3α, thus providing the initial framework for exploring its exceptional role as a lipid sensor under hypoxia.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Ácido Linoleico/metabolismo , Neoplasias/metabolismo , Ácido Oleico/metabolismo , Proteínas Reguladoras de Apoptose , Fatores de Transcrição Hélice-Alça-Hélice Básicos/química , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Clonagem Molecular , Cristalografia por Raios X , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Humanos , Ligantes , Ácido Linoleico/química , Modelos Moleculares , Monoglicerídeos/química , Monoglicerídeos/metabolismo , Neoplasias/genética , Neoplasias/patologia , Ácido Oleico/química , Ligação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Repressoras , Transdução de Sinais , Ácidos Esteáricos/química , Ácidos Esteáricos/metabolismo , Análise Serial de TecidosRESUMO
Tetrahydropyran rings are a common feature of complex polyketide natural products, but much remains to be learned about the enzymology of their formation. The enzyme SalBIII from the salinomycin biosynthetic pathway resembles other polyether epoxide hydrolases/cyclases of the MonB family, but SalBIII plays no role in the conventional cascade of ring opening/closing. Mutation in the salBIII gene gave a metabolite in which ringâ A is not formed. Using this metabolite inâ vitro as a substrate analogue, SalBIII has been shown to form pyran ringâ A. We have determined the X-ray crystal structure of SalBIII, and structure-guided mutagenesis of putative active-site residues has identified Asp38 and Asp104 as an essential catalytic dyad. The demonstrated pyran synthase activity of SalBIII further extends the impressive catalytic versatility of α+ß barrel fold proteins.
RESUMO
3-Dehydroquinase, the third enzyme in the shikimate pathway, is a potential target for drugs against tuberculosis. Whilst a number of potent inhibitors of the Mycobacterium tuberculosis enzyme based on a 3-dehydroquinate core have been identified, they generally show little or no in vivo activity, and were synthetically complex to prepare. This report describes studies to develop tractable and drug-like aromatic analogues of the most potent inhibitors. A range of carbon-carbon linked biaryl analogues were prepared to investigate the effect of hydrogen bond acceptor and donor patterns on inhibition. These exhibited inhibitory activity in the high-micromolar range. The addition of flexible linkers in the compounds led to the identification of more potent 3-nitrobenzylgallate- and 5-aminoisophthalate-based analogues.
Assuntos
Proteínas de Bactérias/antagonistas & inibidores , Desenho de Fármacos , Inibidores Enzimáticos/química , Hidroliases/antagonistas & inibidores , Mycobacterium tuberculosis/enzimologia , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Domínio Catalítico , Cristalografia por Raios X , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Hidroliases/metabolismo , Ácidos Isonicotínicos/síntese química , Ácidos Isonicotínicos/química , Ácidos Isonicotínicos/farmacologia , Simulação de Dinâmica Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Ácido Chiquímico/química , Relação Estrutura-AtividadeRESUMO
Rational ligand design: Schaeffer's acid analogues were identified as novel inhibitors of M.â tuberculosis type II dehydroquinase, a key enzyme of the shikimate pathway. Their likely binding mode was predicted using a combination of ensemble docking and flexible active site residues. Potentially, this scaffold could provide a good starting point for the design of antitubercular agents.
Assuntos
Antituberculosos/química , Antituberculosos/farmacologia , Hidroliases/antagonistas & inibidores , Mycobacterium tuberculosis/enzimologia , Domínio Catalítico , Desenho de Fármacos , Humanos , Hidroliases/química , Hidroliases/metabolismo , Modelos Moleculares , Mycobacterium tuberculosis/efeitos dos fármacos , Ácido Chiquímico/metabolismo , Relação Estrutura-Atividade , Tuberculose/tratamento farmacológicoRESUMO
The shikimate pathway is essential in Mycobacterium tuberculosis and its absence from humans makes the enzymes of this pathway potential drug targets. In the present paper, we provide structural insights into ligand and inhibitor binding to 3-dehydroquinate dehydratase (dehydroquinase) from M. tuberculosis (MtDHQase), the third enzyme of the shikimate pathway. The enzyme has been crystallized in complex with its reaction product, 3-dehydroshikimate, and with six different competitive inhibitors. The inhibitor 2,3-anhydroquinate mimics the flattened enol/enolate reaction intermediate and serves as an anchor molecule for four of the inhibitors investigated. MtDHQase also forms a complex with citrazinic acid, a planar analogue of the reaction product. The structure of MtDHQase in complex with a 2,3-anhydroquinate moiety attached to a biaryl group shows that this group extends to an active-site subpocket inducing significant structural rearrangement. The flexible extensions of inhibitors designed to form π-stacking interactions with the catalytic Tyr24 have been investigated. The high-resolution crystal structures of the MtDHQase complexes provide structural evidence for the role of the loop residues 19-24 in MtDHQase ligand binding and catalytic mechanism and provide a rationale for the design and efficacy of inhibitors.