RESUMO
(R)-2-(4-hydroxyphenoxy)propionic acid (HPOPA) is a key intermediate for the preparation of aryloxyphenoxypropionic acid herbicides (R-isomer). In order to improve the HPOPA production from the substrate (R)-2-phenoxypropionic acid (POPA) with Beauveria bassiana CCN-A7, static cultivation and H2O2 addition were attempted and found to be conducive to the task at hand. This is the first report on HPOPA production under static cultivation and reactive oxygen species (ROS) induction. On this premise, the cultivation conditions and fermentation medium compositions were optimized. As a result, the optimal carbon source, organic nitrogen source, and inorganic nitrogen source were determined to be glucose, peptone, and ammonium sulfate, respectively. The optimal inoculum size and fermentation temperature were 13.3% and 28°C, respectively. The significant factors including glucose, peptone, and H2O2, identified based on Plackett-Burman design, were further optimized through Central Composite Design (CCD). The optimal concentrations/amounts were as follows: glucose 38.81 g/l, peptone 7.28 g/l, and H2O2 1.08 ml/100 ml. Under the optimized conditions, HPOPA titer was improved from 9.60 g/l to 19.53 g/l, representing an increase of 2.03- fold. The results obtained in this work will provide novel strategies for improving the biosynthesis of hydroxy aromatics.
Assuntos
Beauveria/metabolismo , Meios de Cultura/química , Peróxido de Hidrogênio/metabolismo , Propionatos/metabolismo , Carbono , Suplementos Nutricionais , Fermentação , Nitrogênio/metabolismo , Espécies Reativas de Oxigênio , TemperaturaRESUMO
Romipeptides A and B (1 and 2), two new romidepsin derivatives, and three known compounds, chromopeptide A (3), romidepsin (4) and valine-leucine dipeptide (5) were isolated from the fermentation broth of Chromobacterium violaceum No. 968. Their structures were elucidated by interpretation of their UV, HR-ESI-MS and NMR spectra. The absolute configuration of compound 1 and 2 were established by single crystal X-ray diffraction analysis. Compounds 1-5 were evaluated for their anti-proliferative activities against three human cancer cell lines, SW620, HL60, and A549. The results showed most of these compounds exhibited antitumor activities in vitro, in which compound 2 displayed potent cytotoxicity to SW620, HL60 and A549 cell lines, with IC50 of 12.5, 6.7 and 5.7 nmol·L-1, respectively.
Assuntos
Antineoplásicos/farmacologia , Chromobacterium/metabolismo , Depsipeptídeos/química , Depsipeptídeos/farmacologia , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Técnicas de Química Analítica , Dipeptídeos/química , Ensaios de Seleção de Medicamentos Antitumorais , Fermentação , Humanos , Estrutura Molecular , Peptídeos Cíclicos/químicaRESUMO
In the present study, we introduced point mutations into Ac_rapA which encodes a polyketide synthase responsible for rapamycin biosynthesis in Actinoplanes sp. N902-109, in order to construct a mutant with an inactivated enoylreductase (ER) domain, which was able to synthesize a new rapamycin analog. Based on the homologous recombination induced by double-strand breaks in chromosome mediated by endonuclease I-SceI, the site-directed mutation in the first ER domain of Ac_rapA was introduced using non-replicating plasmid pLYERIA combined with an I-SceI expression plasmid. Three amino acid residues of the active center, Ala-Gly-Gly, were converted to Ala-Ser-Pro. The broth of the mutant strain SIPI-027 was analyzed by HPLC and a new peak with the similar UV spectrum to that of rapamycin was found. The sample of the new peak was prepared by solvent extraction, column chromatography, and crystallization methods. The structure of new compound, named as SIPI-rapxin, was elucidated by determining and analyzing its MS and NMR spectra and its biological activity was assessed using mixed lymphocyte reaction (MLR). An ER domain-deficient mutant of Actinoplanes sp. N902-109, named as SIPI-027, was constructed, which produced a novel rapamycin analog SIPI-rapxin and its structure was elucidated to be 35, 36-didehydro-27-O-demethylrapamycin. The biological activity of SIPI-rapxin was better than that of rapamycin. In conclusion, inactivation of the first ER domain of rapA, one of the modular polyketide synthase responsible for macro-lactone synthesis of rapamycin, gave rise to a mutant capable of producing a novel rapamycin analog, 35, 36-didehydro-27-O-demethylrapamycin, demonstrating that the enoylreductase domain was responsible for the reduction of the double bond between C-35 and C-36 during rapamycin synthesis.
Assuntos
Antibacterianos/química , Antibacterianos/metabolismo , Micromonosporaceae/metabolismo , Sirolimo/análogos & derivados , Sirolimo/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Engenharia Genética , Micromonosporaceae/química , Micromonosporaceae/enzimologia , Micromonosporaceae/genética , Mutação , Policetídeo Sintases/química , Policetídeo Sintases/genética , Policetídeo Sintases/metabolismo , Domínios ProteicosRESUMO
The aim of the study was to investigate the anti-proliferation and apoptosis-inducing effects of S1, a novel tetrandrine derivative, in human gastric cancer BGC-823 cells and explore the possible mechanism of action. The anti-proliferative activity was determined by MTT assay; the induction of cell cycle arrest and apoptosis were detected by flow cytometry. Quantitative real time RT-PCR and Western blotting were used to evaluate the mRNA and protein expression levels in mitochondrial pathway. S1 significantly reduced cell viability and induced a G2/M phase arrest and apoptosis in dose- and time-dependent manner. Further studies showed that S1 increased mRNA and protein expression of Bax and the Bax/Bcl-2 ratio. Moreover, S1 decreased the protein expression of procaspase-9 and procaspase-3, suggesting that the induction of apoptosis may be related to the alteration of the ratio of Bax/Bcl-2 and the activation of caspases. These findings suggested that S1 merits further investigation as a novel therapeutic agent for the treatment of human gastric cancer.
Assuntos
Antineoplásicos/farmacologia , Benzilisoquinolinas/farmacologia , Proliferação de Células/efeitos dos fármacos , Neoplasias Gástricas/fisiopatologia , Apoptose/efeitos dos fármacos , Benzilisoquinolinas/química , Caspase 3/genética , Caspase 3/metabolismo , Caspase 9/genética , Caspase 9/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Humanos , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/enzimologia , Neoplasias Gástricas/genética , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismoRESUMO
Shikimic acid (SA) is the key synthetic material for the chemical synthesis of Oseltamivir, which is prescribed as the front-line treatment for serious cases of influenza. Multi-gene expression vector can be used for expressing the plurality of the genes in one plasmid, so it is widely applied to increase the yield of metabolites. In the present study, on the basis of a shikimate kinase genetic defect strain Escherichia coli BL21 (ΔaroL/aroK, DE3), the key enzyme genes aroG, aroB, tktA and aroE of SA pathway were co-expressed and compared systematically by constructing a series of multi-gene expression vectors. The results showed that different gene co-expression combinations (two, three or four genes) or gene orders had different effects on the production of SA. SA production of the recombinant BL21-GBAE reached to 886.38 mg·L(-1), which was 17-fold (P < 0.05) of the parent strain BL21 (ΔaroL/aroK, DE3).
Assuntos
Proteínas de Escherichia coli/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Ácido Chiquímico/metabolismo , Escherichia coli/enzimologia , Proteínas de Escherichia coli/metabolismo , Plasmídeos/genética , Plasmídeos/metabolismoRESUMO
The present study was designed to identify the difference between two rapamycin biosynthetic gene clusters from Streptomyces hygroscopicus ATCC29253 and Actinoplanes sp. N902-109 by comparing the sequence and organization of the gene clusters. The biosynthetic gene cluster for rapamycin in Streptomyces hygroscopicus ATCC29253 was reported in 1995. The second rapamycin producer, Actinoplanes sp. N902-109, which was isolated in 1995, could produce more rapamycin than Streptomyces hygroscopicus ATCC29253. The genomic map of Actinoplanes sp. N902-109 has been elucidated in our laboratory. Two gene clusters were compared using the online software anti-SMASH, Glimmer 3.02 and Subsystem Technology (RAST). Comparative analysis revealed that the organization of the multifunctional polyketide synthases (PKS) genes: RapA, RapB, RapC, and NRPS-like RapP were identical in the two clusters. The genes responsible for precursor synthesis and macrolactone modification flanked the PKS core region in N902-109, while the homologs of those genes located downstream of the PKS core region in ATCC29253. Besides, no homolog of the gene encoding a putative type II thioesterase that may serve as a PKS "editing" enzyme accounted for over-production of rapamycin in N902-109, was found in ATCC29253. Furthermore, no homologs of genes rapQ (encoding a methyltransferase) and rapG in N902-109 were found in ATCC29253, however, an extra rapM gene encoding methyltransferase was discovered in ATCC29253. Two rapamycin biosynthetic gene clusters displayed overall high homology as well as some differences in gene organization and functions.