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1.
Sci China Life Sci ; 62(12): 1638-1654, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31820200

RESUMO

Staurosporine, belonging to indolocarbazole compounds, is regarded as an excellent lead compound for synthesizing antitumor agents as a potent inhibitor against various protein kinases. In this study, two separate clusters (cluster A and cluster B), corresponding to biosyntheses of K-252c (staurosporine aglycone) and sugar moiety, were identified in Streptomyces fradiae CGMCC 4.576 and heterologously expressed in Streptomyces coelicolor M1146 separately or together. StaR, a cluster-situated LAL family regulator, activates staurosporine biosynthesis by binding to the promoter regions of staO-staC and staG-staN. The conserved sequences GGGGG and GCGCG were found through gradually truncating promoters of staO and staG, and further determined by mutational experiments. Overexpression of staR with the supplementation of 0.01 g L-1 FeSO4 increased staurosporine production to 5.2-fold compared with that of the parental strain Streptomyces fradiae CGMCC 4.576 in GYM medium. Our results provided an approach for improvement of staurosporine production mediated by a positive regulator and established the basis for dissecting the regulatory mechanisms of other indolocarbazole compounds with clinical application value.

2.
Appl Microbiol Biotechnol ; 103(5): 2263-2275, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30685809

RESUMO

Neomycin, an aminoglycoside antibiotic, is widely used in the livestock husbandry due to its higher antimicrobial activity and availability of feed additives in animals. However, its production yield is relatively low and cannot meet the needs of developing market and clinical application. Here, the entire natural neo cluster was cloned from Streptomyces fradiae CGMCC 4.576 by φBT1 integrase-mediated site-specific recombination. Then, the rational reconstruction of the neo cluster was performed by using λ-Red-mediated PCR targeting for improving neomycin production. In order to coordinate with this attempt, the supplementation of suitable precursors was carried out. The constructed recombinant strain Sf/pKCZ03 has multi-copy of the neo cluster modified by disrupting the negative regulatory gene neoI and replacing the native promoter of the neoE-D with PkasO*. Compared to the yield (1282 mg/L) of Streptomyces fradiae CGMCC 4.576, the engineered strain Sf/pKCZ03 had a 36% enhancement of neomycin production. Quantitative real-time PCR analysis revealed the increased transcription of structural genes (neoE, neoB, neoL, aacC8) and regulatory genes (neoR, neoH) in Sf/pKCZ03. Additionally, under the supplementation of 1 g/L N-acetyl-D-glucosamine and 5 g/L L-glutamine, the yield of engineered strain Sf/pKCZ03 showed 62% and 107% improvements compared to that of the wild-type strain in the original medium, respectively. These findings demonstrated that engineering the antibiotic gene cluster in combination with precursors feeding was an effective approach for strain improvement, and would be potentially extended to other Streptomyces for large-scale production of commercialized antibiotics.


Assuntos
Antibacterianos/biossíntese , Neomicina/biossíntese , Engenharia de Proteínas/métodos , Streptomyces/genética , Streptomyces/metabolismo , Clonagem Molecular/métodos , Testes de Sensibilidade Microbiana , Família Multigênica/genética , Staphylococcus aureus/efeitos dos fármacos
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