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Heterologous Production of Clavulanic Acid Intermediates in Streptomyces venezuelae
Biplav Shrestha,디페쉬,Sumangala Darsandhari,라메쉬,Anaya Raj Pokhrel,Hum Nath Jnawali,송재경 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.4
Heterologous expression can enhance production of diverse secondary metabolites by redirecting precursor pools towards compound of interest. In this study, Streptomyces venezuelae YJ028 was utilized as the heterologous host for the expression of four structural clavulanic acid biosynthesis genes, which encode carboxyethylarginine synthase (ceas2), β-lactam synthetase (bls2), clavaminate synthase (cas2), and proclavaminate amidinohydrolase (pah2). These genes were cloned into pIBR25 expression vector containing ermE* promoter to generate pBS4. The cas2 gene was also cloned into pSET152 to generate pCas2. It was then integrated into the genome of S. venezuelae YJ028. Upon metabolite profiling of recombinant strains by ultra-pressure liquid chromatography-photodiode array (UPLC-PDA) and high resolution liquid chromatography quadruple time-offlight electrospray ionization mass spectrometry (HR-LCQTOF- ESI/MS), the production of following clavulanic acid intermediates in S. venezuelae recombinant were confirmed: deoxygaunidinoproclavaminic acid, guanidinoproclavaminic acid, and dihydroclavaminic acid. This work demonstrates the production of β-lactam intermediates of the clavulanic acid pathway by heterologous expression in S. venezuelae YJ028.
Biosynthesis of a novel fistein glycoside from engineered Escherichia coli
Biplav Shrestha,Ramesh Prasad Pandey,PrakashParajuli,SumangalaDarsandhari,Jae Kyung Sohng 한국당과학회 2018 한국당과학회 학술대회 Vol.2018 No.01
Fisetin (3,7,3’,4’-tetrahydroxyflavone) belongs to the flavonol subgroup of flavonoids and is found in several fruits and vegetables. Fisetin has high medicinal value and is useful natural agent against cancer and evaluated for its potential inhibitory role against cancer on cells and animal models. To efficiently diversify the therapeutic uses of fisetin, Escherichia coli was harnessed as a production factory and E. coli BL21(DE3)/ΔpgiΔzwfΔgalU mutant was engineered by overexpressing thymidine diphosphate (dTDP)-D-glucose synthase (tgs), dTDP-D-glucose 4,6-dehydratase (dh), and a sugar aminotransferase (wecE) from different sources to produce a pool of dTDP-4-amino-4,6-dideoxy-D-gal actose in the cell cytosol. To this recombinant mutant, two Arabidopsis thaliana glycosyltransferases (ArGT-3 and ArGT-4) were overexpressed to generate two glycosylation platforms (E. coli BL21(DE3)/ΔpgiΔzwfΔgalUTDW-3 and E. coli BL21(DE3)/Δ pgiΔzwfΔgalUTDW-4), which were accessed for the glycosylation of fisetin. As a result, one of the two systems, E. coli BL21(DE3)/ΔpgiΔzwfΔgalUTDW-3, was able to conjugate 4-amino-4,6-dideoxy-D-galactose sugar at the 3-OH position of fisetin, producing an unnatural fisetin 3-O-4-amino-4,6-dideoxy-D-galactoside.