RESUMEN
The removal of mis-incorporated nucleotides by proofreading activity ensures DNA replication fidelity. Whereas the ε-exonuclease DnaQ is a well-established proofreader in the model organism Escherichia coli, it has been shown that proofreading in a majority of bacteria relies on the polymerase and histidinol phosphatase (PHP) domain of replicative polymerase, despite the presence of a DnaQ homolog that is structurally and functionally distinct from E. coli DnaQ. However, the biological functions of this type of noncanonical DnaQ remain unclear. Here, we provide independent evidence that noncanonical DnaQ functions as an additional proofreader for mycobacteria. Using the mutation accumulation assay in combination with whole-genome sequencing, we showed that depletion of DnaQ in Mycolicibacterium smegmatis leads to an increased mutation rate, resulting in AT-biased mutagenesis and increased insertions/deletions in the homopolymer tract. Our results showed that mycobacterial DnaQ binds to the ß clamp and functions synergistically with the PHP domain proofreader to correct replication errors. Furthermore, the loss of dnaQ results in replication fork dysfunction, leading to attenuated growth and increased mutagenesis on subinhibitory fluoroquinolones potentially due to increased vulnerability to fork collapse. By analyzing the sequence polymorphism of dnaQ in clinical isolates of Mycobacterium tuberculosis (Mtb), we demonstrated that a naturally evolved DnaQ variant prevalent in Mtb lineage 4.3 may enable hypermutability and is associated with drug resistance. These results establish a coproofreading model and suggest a division of labor between DnaQ and PHP domain proofreader. This study also provides real-world evidence that a mutator-driven evolutionary pathway may exist during the adaptation of Mtb.
Asunto(s)
Replicación del ADN , Mycobacterium smegmatis/genética , Mycobacterium smegmatis/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , ADN Bacteriano/genética , ADN Bacteriano/metabolismo , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/metabolismo , MutaciónRESUMEN
OBJECTIVE: We conducted a systematic review and meta-analysis to explore the relationship between blood pituitary adenylate cyclase-activating polypeptide (PACAP) levels and migraine. BACKGROUND: PACAP is involved in the onset of migraine, but the results from clinical studies on PACAP level variations across different periods of migraine are conflicting. METHODS: We systematically searched for observational studies that reported PACAP levels in people with migraine and non-migraine controls published in English from the PubMed, Web of Science, and Ovid electronic databases, or in Chinese from the Chinese National Knowledge Infrastructure and the WanFang Med database. The Newcastle-Ottawa Quality Assessment Scale was used to assess the quality of the included studies. The quality of evidence for each outcome was assessed according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines. RESULTS: Of the 514 identified studies, 8 were eligible for inclusion. There was a "very low" level of evidence suggesting that the PACAP level is negatively correlated with migraine disease duration in adults with migraine (summary r = -0.35, 95% confidence interval [CI] -0.49 to -0.22) and that the PACAP is higher in people with migraine during the ictal period than in the interictal period (standardized mean difference = 0.41, 95% CI 0.17 to 0.66) for both adults and children with migraine. Adult patients with episodic migraine (weighted mean difference [WMD] = -9.58 pg/mL, 95% CI -13.41 to -5.75 pg/mL) or chronic migraine (WMD = -10.93 pg/mL, 95% CI -15.57 to -6.29 pg/mL) had lower blood PACAP levels than non-migraine controls during the interictal period, supported by a "low" or "very low" quality of evidence, respectively, according to the GRADE rules. CONCLUSION: There is a very low certainty of evidence suggesting that the PACAP level is negatively correlated with migraine disease duration of adults with migraine and it varies greatly among different periods of migraine of both adults and children with migraine.
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Trastornos Migrañosos , Estudios Observacionales como Asunto , Polipéptido Hipofisario Activador de la Adenilato-Ciclasa , Humanos , Trastornos Migrañosos/sangre , Polipéptido Hipofisario Activador de la Adenilato-Ciclasa/sangreRESUMEN
Direct cloning of biosynthetic gene clusters (BGCs) from microbial genomes facilitates natural product-based drug discovery. Here, by combining Cas12a and the advanced features of bacterial artificial chromosome library construction, we developed a fast yet efficient in vitro platform for directly capturing large BGCs, named CAT-FISHING (CRISPR/Cas12a-mediated fast direct biosynthetic gene cluster cloning). As demonstrations, several large BGCs from different actinomycetal genomic DNA samples were efficiently captured by CAT-FISHING, the largest of which was 145 kb with 75% GC content. Furthermore, the directly cloned, 110 kb long, cryptic polyketide encoding BGC from Micromonospora sp. 181 was then heterologously expressed in a Streptomyces chassis. It turned out to be a new macrolactam compound, marinolactam A, which showed promising anticancer activity. Our results indicate that CAT-FISHING is a powerful method for complicated BGC cloning, and we believe that it would be an important asset to the entire community of natural product-based drug discovery.
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Productos Biológicos , Streptomyces , Sistemas CRISPR-Cas , Clonación Molecular , Familia de Multigenes , Streptomyces/genéticaRESUMEN
A new dimeric C-glycoside polyketide chrysomycin F (1), along with four new monomeric compounds, chrysomycins G (2), H (3), I (4), J (5), as well as three known analogues, chrysomycins A (6), B (7), and C (8), were isolated and characterised from a strain of Streptomyces sp. obtained from a sediment sample collected from the South China Sea. Their structures were determined by detailed spectroscopic analysis. Chrysomycin F contains two diastereomers, whose structures were further elucidated by a biomimetic [2 + 2] photodimerisation of chrysomycin A. Chrysomycins B and C showed potent anti-tuberculosis activity against both wild-type Mycobacterium tuberculosis and a number of clinically isolated MDR M. tuberculosis strains.
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Antituberculosos , Pruebas de Sensibilidad Microbiana , Mycobacterium tuberculosis , Policétidos , Streptomyces , Streptomyces/química , Streptomyces/metabolismo , Mycobacterium tuberculosis/efectos de los fármacos , Antituberculosos/farmacología , Antituberculosos/química , Antituberculosos/aislamiento & purificación , Policétidos/farmacología , Policétidos/química , Policétidos/aislamiento & purificación , Glicósidos/química , Glicósidos/farmacología , Glicósidos/aislamiento & purificación , China , Estructura Molecular , Antraquinonas/farmacología , Antraquinonas/química , Antraquinonas/aislamiento & purificaciónRESUMEN
The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mediates membrane fusion to allow entry of the viral genome into host cells. To understand its detailed entry mechanism and develop a specific entry inhibitor, in situ structural information on the SARS-CoV-2 spike protein in different states is urgent. Here, by using cryo-electron tomography, we observed both prefusion and postfusion spikes in ß-propiolactone-inactivated SARS-CoV-2 virions and solved the in situ structure of the postfusion spike at nanometer resolution. Compared to previous reports, the six-helix bundle fusion core, the glycosylation sites, and the location of the transmembrane domain were clearly resolved. We observed oligomerization patterns of the spikes on the viral membrane, likely suggesting a mechanism of fusion pore formation.
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SARS-CoV-2/ultraestructura , Glicoproteína de la Espiga del Coronavirus/química , Secuencias de Aminoácidos , Animales , Chlorocebus aethiops , Microscopía por Crioelectrón , Tomografía con Microscopio Electrónico , Glicosilación , Dominios Proteicos , Multimerización de Proteína , Glicoproteína de la Espiga del Coronavirus/metabolismo , Células VeroRESUMEN
Terpene synthases (TPSs) play pivotal roles in generating diverse terpenoids through complex cyclization pathways. Protein engineering of TPSs offers a crucial approach to expanding terpene diversity. However, significant potential remains untapped due to limited understanding of the structure-function relationships of TPSs. In this investigation, using a joint approach of molecular dynamics simulations-assisted engineering and site-directed mutagenesis, we manipulated the aromatic residue cluster (ARC) of a bifunctional terpene synthase (BFTPS), Pestalotiopsis fici nigtetraene synthase (PfNS). This led to the discovery of previously unreported catalytic functions yielding different cyclization patterns of sesterterpenes. Specifically, a quadruple variant (F89A/Y113F/W193L/T194W) completely altered PfNS's function, converting it from producing the bicyclic sesterterpene nigtetraene to the tricyclic ophiobolin F. Additionally, analysis of catalytic profiles by double, triple, and quadruple variants demonstrated that the ARC functions as a switch, unprecedently redirecting the production of 5/11 bicyclic (Typeâ B) sesterterpenes to 5/15 bicyclic (Typeâ A) ones. Molecular dynamics simulations and theozyme calculations further elucidated that, in addition to cation-π interactions, C-Hâ â â π interactions also play a key role in the cyclization patterns. This study offers a feasible strategy in protein engineering of TPSs for various industrial applications.
RESUMEN
Friedel-Crafts acylation (FCA) is a highly beneficial approach in organic chemistry for creating the important C-C bonds that are necessary for building intricate frameworks between aromatic substrates and an acyl group. However, there are few reports about enzyme catalyzed FCA reactions. In this study, 4-acyl-5-aminoimidazole alkaloids (AAIAs), streptimidazoles A-C (1-3), and the enantiopure (+)-nocarimidazole C (4) as well as their ribosides, streptimidazolesides A-D (5-8), were identified from the fermentation broth of Streptomyces sp. OUCMDZ-944 or heterologous S. coelicolor M1154 mutant. The biosynthetic gene cluster (smz) was identified, and the biosynthetic pathway of AAIAs was elucidated for the first time. In vivo and in vitro studies proved the catalytic activity of the four essential genes smzB, -C, -E, and -F for AAIAs biosynthesis and clarified the biosynthetic process of the alkaloids. The ligase SmzE activates fatty acyl groups and connects them to the acyl carrier protein (ACP) holo-SmzF. Then, the acyl group is transferred onto the key residue Cys49 of SmzB, a new Friedel-Crafts acyltransferase (FCase). Subsequently, the FCA reaction between the acyl groups and 5-aminoimidazole ribonucleotide (AIR) occurs to generate the key intermediate AAIA-nucleotides catalyzed by SmzB. Finally, the hydrolase SmzC catalyzes the N-glycosidic bond cleavage of the intermediates to form AAIAs. Structural simulation, molecular modeling, and mutational analysis of SmzB showed that Tyr26, Cys49, and Tyr93 are the key catalytic residues in the C-C bond formation of the acyl chain of AAIAs, providing mechanistic insights into the enzymatic FCA reaction.
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Aciltransferasas , Imidazoles , Aciltransferasas/química , Proteína Transportadora de Acilo/química , CatálisisRESUMEN
Attaching polymers, especially polyethylene glycol (PEG), to protein drugs has emerged as a successful strategy to prolong circulation time in the bloodstream. The hypothesis is that the flexible chain wobbles on the protein's surface, thus resisting potential nonspecific adsorption. Such a theoretical framework may be challenged when a helical polyglutamate is used to conjugate with target proteins. In this study, we investigated the structure-activity relationships of polyglutamate-interferon conjugates P(EG3Glu)-IFN using molecular simulations. Our results show that the local crowding effect induced by oligoethylene glycols (i.e., EG3) is the primary driving force for helix formation in P(EG3Glu), and its helicity can be effectively increased by reducing the free volume of the two termini. Furthermore, it was found that the steric hindrance induced by IFN is not conductive to the helicity of P(EG3Glu) but contributes to its dominant orientation relative to interferon. The orientation of IFN relative to the helical P(EG3Glu) can help to protect the protein drug from neutralizing antibodies while maintaining its bioactivity. These findings suggest that the helical structure and its orientation are critical factors to consider when updating the theoretical framework for protein-polymer conjugates.
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Interferones , Ácido Poliglutámico , Interferones/química , Polietilenglicoles/química , Polímeros/química , ProteínasRESUMEN
In their recent Angewandte Chemie publication (doi: 10.1002/anie.202112063), Cen, Wang, Zhou etâ al. reported the crystal structure of a ternary complex of the non-heme iron endoperoxidase FtmOx1 (PDB entryâ 7ETK). The biochemical data assessed in this study were from a retracted study (doi: 10.1038/nature15519) by Zhang, Liu, Zhang etâ al.; no additional biochemical data were included, yet there was no discussion on the source of the biochemical data in the report by Cen, Wang, Zhou etâ al. Based on this new crystal structure and subsequent QM/MM-MD calculations, Cen, Wang, Zhou etâ al. concluded that their work provided evidence supporting the CarC-like mechanistic model for FtmOx1 catalysis. However, the authors did not accurately describe either the CarC-like model or the COX-like model, and they did not address the differences between them. Further, and contrary to their interpretations in the manuscript, the authors' data are consistent with the COX-like model once the details of the CarC-like and COX-like models have been carefully analyzed.
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Biocatálisis , Modelos Moleculares , Estructura Terciaria de ProteínaRESUMEN
Peptide-based biomaterials exhibit great potentials in developing drug delivery platforms due to their biocompatibility and biodegradability beyond poly(ethylene glycol). How different amino acids in peptides used for delivery play their roles is still unclear at the microscopic level. This work compared the assembly behaviors of a series of peptides around interferon-α (IFN-α). Through all-atom molecular simulations, the sequence effect of peptides on delivering interferon-α was quantitively characterized. The hydrophobic elastin-like peptide (VPGAG)n preferred to self-aggregate into dense clusters, rather than encapsulate IFN-α. The hydrophilic zwitterionic peptides with repeating unit "KE" tended to phase-separate from IFN-α in the mixture. In contrast, peptides with a hybrid sequence, i.e., (VPKEG)n, exhibited the highest contact preference, and the formed protective shell endowed IFN-α with better thermal stability and stealth property and achieved a subtle balance between protecting IFN-α and subsequent releasing. Further energy decomposition analysis revealed that the positively charged Lys contributed most to the binding affinity while the negatively charged Glu contributed most to the hydrophilic property of peptide-based materials. In summary, this article reveals why peptides composed of repeating hydrophobic and charged residues could be a potential choice for delivering therapeutic proteins in the form of solution.
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Interferón-alfa , Simulación de Dinámica Molecular , Aminoácidos , Interacciones Hidrofóbicas e Hidrofílicas , PéptidosRESUMEN
Fungal bifunctional terpene synthases (BFTSs) have been reported to contribute to the biosynthesis of a variety of di/sesterterpenes via different carbocation transportation pathways. Genome mining of new BFTSs from unique fungal resources will, theoretically, allow for the identification of new terpenes. In this study, we surveyed the distribution of BFTSs in our in-house collection of 430 pathogenetic fungi and preferred two BFTSs (CsSS and NnNS), long distance from previously characterized BFTSs and located in relatively independent branches, based on the established phylogenetic tree. The heterologous expression of the two BFTSs in Aspergillus oryzae and Saccharomyces cerevisiae led to the identification of two new sesterterpenes separately, 5/12/5 tricyclic type-A sesterterpene (schultriene, 1) for CsSS and 5/11 bicyclic type-B sesterterpene (nigtetraene, 2) for NnNS. In addition, to the best of our knowledge, 2 is the first 5/11 bicyclic type-B characterized sesterterpene to date. On the basis of this, the plausible cyclization mechanisms of 1 and 2 were proposed based on density functional theory calculations. These new enzymes and their corresponding terpenes suggest that the chemical spaces produced by BFTSs remain large and also provide important evidences for further protein engineering for new terpenes and for understanding of cyclization mechanism catalyzed by BFTSs. KEY POINTS: ⢠Genome mining of two BFTSs yields two new sesterterpenoids correspondingly. ⢠Identification of the first 5/11 ring system type-B product. ⢠Parse out the rational cyclization mechanism of isolated sesterterpenoids.
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Aspergillus oryzae , Sesterterpenos , Aspergillus oryzae/genética , Aspergillus oryzae/metabolismo , Ciclización , Hongos/metabolismo , Filogenia , Sesterterpenos/metabolismo , TerpenosRESUMEN
Marine microbes provide an important resource to discover new chemical compounds with biological activities beneficial to drug discovery. In our study, two new polyene macrolides, pyranpolyenolides A (1) and B (2), and one new natural cyclic peptide (9), together with two known polyenes (7 and 8) and three known cyclic peptides (10-12), were isolated from a culture of the marine Streptomyces sp. MS110128. In addition, four new polyene macrolides, pyranpolyenolides C-F (3-6), were identified as olefin geometric isomers that were most likely produced by photochemical conversion during the cultivation or isolation procedures. The pyranpolyenolides are 32-membered macrolides endowed with a conjugated tetraene and several pairs of 1,3-dihydroxyl groups. Pyranpolyenolides that contain a hydropyran group have not been previously reported. Four cyclic peptides (9-12) showed significant activities against Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant S. aureus with supporting MIC values ranging from 0.025 to 1.25 µg/mL. These cyclic peptides containing piperazic moieties showed moderate activities with MIC values of 12.5 µg/mL against Bacille Calmette Guerin (BCG), an attenuated form of the bovine. Additionally, cyclic peptide 12 showed moderate antifungal activity against Candida albicans with an MIC value of 12.5 µg/mL. KEY POINTS: ⢠Discovery of new polyenes and cyclic peptides from a marine-derived Actinomycete. ⢠Cyclic peptides containing piperazic moieties exhibited good antibacterial activity.
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Staphylococcus aureus Resistente a Meticilina , Streptomyces , Animales , Antibacterianos , Bovinos , Macrólidos , Pruebas de Sensibilidad Microbiana , Péptidos Cíclicos , Polienos , PolímerosRESUMEN
Fungal terpenoids catalyzed by bifunctional terpene synthases (BFTSs) possess interesting bioactive and chemical properties. In this study, an integrated approach of genome mining, heterologous expression, and in vitro enzymatic activity assay was used, and these identified a unique BFTS sub-clade critical to the formation of a 5-15 trans-fused bicyclic sesterterpene preterpestacin I (1). The 5-15 bicyclic BFTS gene clusters were highly conserved but showed relatively wide phylogenetic distribution across several species of the diverged fungal classes Dothideomycetes and Sordariomycetes. Further genomic organization analysis of these homologous biosynthetic gene clusters from this clade revealed a glycosyltransferase from the graminaceous pathogen Bipolaris sorokiniana isolate BS11134, which was absent in other 5-15 bicyclic BFTS gene clusters. Targeted isolation guided by BFTS gene deletion led to the identification of two new sesterterpenoids (4, and 6) from BS11134. Compounds 2 and 4 showed moderate effects on LPS-induced nitrous oxide production in the murine macrophage-like cell line RAW264.7 with in vitro inhibition rates of 36.6 ± 2.4% and 24.9 ± 2.1% at 10 µM, respectively. The plausible biosynthetic pathway of these identified compounds was proposed as well. This work revealed that phytopathogenic fungi can serve as important sources of active terpenoids via systematic analysis of the genomic organization of BFTS biosynthetic gene clusters, their phylogenetic distribution in fungi, and cyclization properties of their metabolic products. KEY POINTS: ⢠Genome mining of the first BFTS BGC harboring a glycosyltransferase. ⢠Gene-deletion guided isolation revealed three novel 5-15 bicyclic sesterterpenoids. ⢠Biosynthetic pathway of isolated sesterterpenoids was proposed.
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Vías Biosintéticas , Hongos , Animales , Antiinflamatorios , Vías Biosintéticas/genética , Hongos/genética , Ratones , Familia de Multigenes , Filogenia , TerpenosRESUMEN
The heme-copper oxidase superfamily comprises cytochrome c and ubiquinol oxidases. These enzymes catalyze the transfer of electrons from different electron donors onto molecular oxygen. A B-family cytochrome c oxidase from the hyperthermophilic bacterium Aquifex aeolicus was discovered previously to be able to use both cytochrome c and naphthoquinol as electron donors. Its molecular mechanism as well as the evolutionary significance are yet unknown. Here we solved its 3.4â Å resolution electron cryo-microscopic structure and discovered a novel dimeric structure mediated by subunit I (CoxA2) that would be essential for naphthoquinol binding and oxidation. The unique structural features in both proton and oxygen pathways suggest an evolutionary adaptation of this oxidase to its hyperthermophilic environment. Our results add a new conceptual understanding of structural variation of cytochrome c oxidases in different species.
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Complejo IV de Transporte de Electrones/metabolismo , Hemo/metabolismo , Aquifex/metabolismo , Sitios de Unión , Microscopía por Crioelectrón , Dimerización , Complejo IV de Transporte de Electrones/química , Electrones , Hemo/química , Naftoquinonas/química , Naftoquinonas/metabolismo , Oxidación-Reducción , Estructura Cuaternaria de Proteína , Subunidades de Proteína/química , Subunidades de Proteína/metabolismoRESUMEN
Avermectin (AVM) refers to eight macrolides containing a common l-oleandrosyl disaccharide chain indispensable to their antiparasitic bioactivities. We delineated the biosynthetic pathway of TDP-ß-l-oleandrose (1), the sugar donor of AVM, by characterizing AveBVIII, AveBV, and AveBVII as TDP-sugar 3-ketoreductase, 5-epimerase, and 3-O-methyltransferase, respectively. On the basis of this pathway, we successfully reconstituted the biosynthesis of 1 in Escherichia coli. Our work completes the biosynthetic pathway of AVM and lays a solid foundation for further studies.
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Desoxiazúcares/biosíntesis , Hexosas/biosíntesis , Ivermectina/análogos & derivados , Antibacterianos , Biología Computacional , ADN Bacteriano/química , ADN Bacteriano/genética , Escherichia coli/enzimología , Escherichia coli/metabolismo , Ivermectina/síntesis química , Metiltransferasas/metabolismo , Estructura Molecular , UDPglucosa 4-Epimerasa/metabolismoRESUMEN
Polyketide-terpenoid hybrid compounds are one of the largest families of meroterpenoids, with great potential for drug development for resistant pathogens. Genome sequence analysis of secondary metabolite gene clusters of a phytopathogenic fungus, Bipolaris sorokiniana 11134, revealed a type I polyketide gene cluster, consisting of highly reducing polyketide synthase, non-reducing polyketide synthase, and adjacent prenyltransferase. MS- and UV-guided isolations led to the isolation of ten meroterpenoids, including two new compounds: 19-dehydroxyl-3-epi-arthripenoid A (1) and 12-keto-cochlioquinone A (2). The structures of 1-10 were elucidated by the analysis of NMR and high-resolution electrospray ionization mass spectroscopy data. Compounds 5-8 and 10 showed moderate activity against common Staphylococcus aureus and methicillin-resistant S. aureus, with minimum inhibitory concentration (MIC) values of 12.5-100 µg/mL. Compound 5 also exhibited activity against four clinical resistant S. aureus strains and synergistic antifungal activity against Candida albicans with MIC values of 12.5-25 µg/mL. The biosynthetic gene cluster of the isolated compounds and their putative biosynthetic pathway are also proposed. KEY POINTS: ⢠Ten meroterpenoids were identified from B. sorokiniana, including two new compounds. ⢠Cochlioquinone B (5) showed activity against MRSA and synergistic activity against C. albicans. ⢠The biosynthetic gene cluster and biosynthetic pathway of meroterpenoids are proposed. ⢠Genome mining provided a new direction to uncover the diversity of meroterpenoids.
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Antibacterianos/farmacología , Bipolaris/química , Bipolaris/genética , Genoma Fúngico , Policétidos/farmacología , Terpenos/farmacología , Antibacterianos/aislamiento & purificación , Antifúngicos/aislamiento & purificación , Antifúngicos/farmacología , Vías Biosintéticas/genética , Candida albicans/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Familia de Multigenes , Policétidos/aislamiento & purificación , Metabolismo Secundario , Staphylococcus aureus/efectos de los fármacos , Terpenos/aislamiento & purificaciónRESUMEN
Marine microorganisms live in dramatically different environments and have attracted much attention for their structurally unique natural products with potential strong biological activity. Based on the one strain-many compounds (OSMAC) strategy and liquid chromatography mass spectrometry (LC-MS) methods, our continuing efforts on the investigation of novel active compounds from marine Verrucosispora sp. MS100137 has led to the identification of a new polycyclic metabolite, abyssomicin Y (1), together with six known abyssomicin and proximicin analogs (2-7). Abyssomicin Y is a type I abyssomicin with an epoxide group at C-8 and C-9. Compounds 1-3 showed potent inhibitory effects against the influenza A virus; their observed inhibition rates were 97.9%, 98.3%, and 95.9%, respectively, at a concentration of 10 µM, and they displayed lower cytotoxicity than 4. The structures were determined by different NMR techniques and HRMS experiments. This investigation revealed that OSMAC could serve as a useful method for enabling the activation of the silent genes in the microorganism and for the formation of previously unreported active secondary metabolites.
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Antivirales/farmacología , Organismos Acuáticos/química , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Virus de la Influenza A/efectos de los fármacos , Micromonosporaceae/química , Células A549 , Antivirales/aislamiento & purificación , Productos Biológicos/aislamiento & purificación , Productos Biológicos/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/aislamiento & purificación , Cromatografía Liquida , Humanos , Espectrometría de Masas , Metabolismo SecundarioRESUMEN
Respiratory chain complexes convert energy by coupling electron flow to transmembrane proton translocation. Owing to a lack of atomic structures of cytochromeâ bc1 complex (Complexâ III) from thermophilic bacteria, little is known about the adaptations of this macromolecular machine to hyperthermophilic environments. In this study, we purified the cytochromeâ bc1 complex of Aquifex aeolicus, one of the most extreme thermophilic bacteria known, and determined its structure with and without an inhibitor at 3.3â Å resolution. Several residues unique for thermophilic bacteria were detected that provide additional stabilization for the structure. An extra transmembrane helix at the N-terminus of cyt. c1 was found to greatly enhance the interaction between cyt. b and cyt. c1 , and to bind a phospholipid molecule to stabilize the complex in the membrane. These results provide the structural basis for the hyperstability of the cytochromeâ bc1 complex in an extreme thermal environment.
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Transporte de Electrón/genética , Secuencia de Aminoácidos , Humanos , Modelos MolecularesRESUMEN
BACKGROUND: Although reduced red blood cell (RBC) lifespan has been reported to be a contributory factor to anemia in patients with end-stage chronic kidney disease (CKD), there are limited data regarding RBC lifespan in early-stage CKD. Serum erythropoietin (EPO) is considered a primary causative factor of renal anemia. The aims of this study were to compare the RBC lifespan, serum EPO levels, and other renal anemia indicators across CKD-stage groups of patients and to analyze the impacts of etiological factors on renal anemia. METHODS: A cohort of 74 non-smoking patients with CKD were enrolled, including 15 in stage 1, 18 in stage 2, 15 in stage 3, 15 in stage 4, and 11 in stage 5. RBC lifespan was determined by CO breath tests. Potential correlations of hemoglobin (Hb) concentration with RBC lifespan, reticulocyte count (Ret), and levels of EPO, ferritin, folic acid, and vitamin B12 were analyzed. RESULTS: CKD progression was associated with decreases in (Hb) and RBC lifespan. RBC lifespan durations in CKD stages 1-5 were 122 ± 50, 112 ± 26, 90 ± 32, 88 ± 28, and 60 ± 24 days, respectively. RBC lifespan means for the stage 3, 4 and 5 groups were significantly shorter than those for the stage 1 and 2 groups. Serum EPO did not differ significantly between the CKD stage groups. (Hb) correlated directly with RBC lifespan (r = 0.372, p = 0.002) and Ret (r = 0.308, p = 0.011), but did not correlate with serum EPO, ferritin, folic acid, or vitamin B12 levels. CONCLUSIONS: Reduced RBC lifespan in early-stage CKD, demonstrated in this study, suggests that increased RBC destruction may play a more important etiological role in renal anemia than other indicators in patients with CKD.
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Eritrocitos/metabolismo , Insuficiencia Renal Crónica/metabolismo , Anemia , Eritrocitos/citología , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Halogen substituents are important for biological activity in many compounds. Genome-based mining of halogenase along with its biosynthetic gene cluster provided an efficient approach for the discovery of naturally occurring organohalogen compounds. Analysis of the genome sequence of a phytopathogenic fungus Bipolaris sorokiniana 11134 revealed a polyketide gene cluster adjacent to a flavin-dependent halogenase capable of encoding halogenated polyketides, which are rarely reported in phytopathogenic fungi. Furthermore, MS- and UV-guided isolation and purification led to the identification of five chlorine-containing natural products together with seven other chromones and xanthones. Two of the chlorinated compounds and four chromones are new compounds. Their structures were elucidated by NMR spectroscopic analysis and HRESIMS data. The biosynthetic gene clusters of isolated compounds and their putative biosynthetic pathway are also proposed. One new chlorinated compound showed activity against Staphylococcus aureus, methicillin-resistant S. aureus, and three clinical-resistant S. aureus strains with a shared minimum inhibitory concentration (MIC) of 12.5 µg/mL. Genome-based mining of halogenases combined with high-resolution MS- and UV-guided identification provides an efficient approach to discover new halogenated natural products from microorganisms.