RESUMO
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
In celebration of the excellence and breadth of Latin American research achievements across the chemical sciences, we are delighted to present an introduction to the themed collection, Celebrating Latin American talent in chemistry.
RESUMO
Microbial oxidation potentials of extremophiles recovered from Pampo Sul oil field, Campos Basin, Brazil, in pure culture or in consortia, were investigated using high-throughput screening (HTS) and multibioreactions. Camphor (1), cis-jasmone (2), 2-methyl-cyclohexanone (3), 1,2-epoxyoctane (4), phenylethyl acetate (5), phenylethyl propionate (6), and phenylethyl octanoate (7) were used to perform multibioreaction assays. Eighty-two bacterial isolates were recovered from oil and formation water samples and those presenting outstanding activities in HTS assays were identified by sequencing their 16S rRNA genes. These results revealed that most microorganisms belonged to the genus Bacillus and presented alcohol dehydrogenase, monooxygenase, epoxide hydrolase, esterase, and lipase activities.
Assuntos
Bactérias/enzimologia , Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Hidrolases/metabolismo , Oxigenases de Função Mista/metabolismo , Petróleo/microbiologia , Microbiologia da Água , Bactérias/classificação , Bactérias/genética , Proteínas de Bactérias/genética , DNA Bacteriano/genética , Hidrolases/genética , Oxigenases de Função Mista/genética , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
The chemical space covered by natural products is immense and widely unrecognized. Therefore, convenient methodologies to perform wide-ranging evaluation of their functions in nature and potential human benefits (e.g., for drug discovery applications) are desired. This protocol describes the combination of genome mining (GM) and molecular networking (MN), two contemporary approaches that match gene cluster-encoded annotations in whole genome sequencing with chemical structure signatures from crude metabolic extracts. This is the first step towards the discovery of new natural entities. These concepts, when applied together, are defined here as MS-guided genome mining. In this method, the main components are previously designated (using MN), and structurally related new candidates are associated with genome sequence annotations (using GM). Combining GM and MN is a profitable strategy to target new molecule backbones or harvest metabolic profiles in order to identify analogues from already known compounds.
Assuntos
Produtos Biológicos/química , Descoberta de Drogas/métodos , Genômica/métodos , Espectrometria de Massas/métodos , HumanosRESUMO
The genus Streptomyces is characterized by the production of a wide variety of secondary metabolites with remarkable biological activities and broad antibiotic capabilities. The presence of an unprecedented number of genes encoding hydrolytic enzymes with industrial appeal such as epoxide hydrolases (EHs) reveals its resourceful microscopic machinery. The whole-genome sequence of Streptomyces sp. CBMAI 2042, an endophytic actinobacterium isolated from Citrus sinensis branches, was explored by genome mining, and a putative α/ß-epoxide hydrolase named B1EPH2 and encoded by 344 amino acids was selected for functional and structural studies. The crystal structure of B1EPH2 was obtained at a resolution of 2.2â Å and it was found to have a similar fold to other EHs, despite its hexameric quaternary structure, which contrasts with previously solved dimeric and monomeric EH structures. While B1EPH2 has a high sequence similarity to EHB from Mycobacterium tuberculosis, its cavity is similar to that of human EH. A group of 12 aromatic and aliphatic racemic epoxides were assayed to determine the activity of B1EPH2; remarkably, this enzyme was able to hydrolyse all the epoxides to the respective 1,2-diols, indicating a wide-range substrate scope acceptance. Moreover, the (R)- and (S)-enantiomers of styrene oxide, epichlorohydrin and 1,2-epoxybutane were used to monitor enantiopreference. Taken together, the functional and structural analyses indicate that this enzyme is an attractive biocatalyst for future biotechnological applications.
Assuntos
Proteínas de Bactérias/química , Epóxido Hidrolases/química , Streptomyces/enzimologia , Modelos Moleculares , Conformação ProteicaRESUMO
We report here the complete genome sequence of Streptomyces sp. strain RTd22, an endophytic actinobacterium that was isolated from the roots of the Mexican sunflower Tithonia diversifolia The bacterium's 11.1-Mb linear chromosome is predicted to encode a large number of unknown natural products.
RESUMO
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
[reaction: see text] Initial efforts toward the total synthesis of the antifungal antibiotics spirofungins A and B are reported. A short and efficient synthesis of the C9-C20 6,6-spiroketal fragments of both compounds is described. This asymmetric approach uses a very efficient alkylation of a lithiated N,N-dimethylhydrazone followed by spiroketal formation under acidic conditions.
Assuntos
Antifúngicos/síntese química , Piranos/síntese química , Compostos de Espiro/síntese química , Streptomyces/química , Alquilação , Antifúngicos/química , Antifúngicos/farmacologia , Técnicas de Química Combinatória , Estrutura Molecular , Piranos/química , Piranos/farmacologia , Compostos de Espiro/química , Compostos de Espiro/farmacologiaRESUMO
[structure: see text] The asymmetric total synthesis of pironetin, a compound that shows plant growth regulatory activity, immunosuppressive as well as a remarkable antitumoral activity, is described. The approach involves the use of three very efficient Evans oxazolidinone-mediated syn-aldol condensations, a high-yielding coupling between lithium acetylide ethylenediamine complex and a tosylate followed by methylation, and selective reduction to establish the C12-C13 (E) double bond.
Assuntos
Pironas/síntese química , Estrutura Molecular , Pironas/químicaRESUMO
The actinobacterium Streptomyces wadayamensis A23 is an endophyte of Citrus reticulata that produces the antimycin and mannopeptimycin antibiotics, among others. The strain has the capability to inhibit Xylella fastidiosa growth. The draft genome of S. wadayamensis A23 has ~7.0 Mb and 6,006 protein-coding sequences, with a 73.5% G+C content.
RESUMO
[structure: see text] The total synthesis of (+)-crocacin D is described. The convergent asymmetric synthesis relies on the use of a Stille cross-coupling between an (E)-vinyl stannane with an (E)-vinyl iodide to establish the (E,E)-dienamide moiety followed by a mild and efficient copper-catalyzed coupling between (+)-crocacin C and a (Z)-vinyl iodide to establish the challenging (Z)-enamide function.