• Molecules and Cells
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• 제22권2호
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• pp.154-162
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• 2006

The entire gene cluster involved in the biosynthesis of angucyclines Sch 47554 and Sch 47555 was cloned, sequenced, and characterized. Analysis of the nucleotide sequence of genomic DNA spanning 77.5-kb revealed a total of 55 open reading frames, and the deduced products exhibited strong sequence similarities to type II polyketide synthases, deoxysugar biosynthetic enzymes, and a variety of accessory enzymes. The involvement of this gene cluster in the pathway of Sch 47554 and Sch 47555 was confirmed by genetic inactivation of the aromatase, including a portion of the ketoreductase, which was disrupted by inserting the thiostrepton gene.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.627-627
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• 2005

• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.685-690
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• 2007

The deoxysugar biosynthetic gene cluster of Sch 47554/Sch 47555 was cloned from Streptomyces sp. SCC-2136. One of the ORFs, schS6, appeared to encode glucose-1-phosphate thymidylyltransferase, which converts dTTP and glucose-1-phosphate to TDP-D-glucose and pyrophosphate. The dTDP-D-glucose is a key metabolite in prokaryotics as a precursor for a large number of modified deoxysugars, and these deoxysugars are a maj or part of various antibiotics, ranging from glycosides to macrolides. SchS6 was expressed in E. coli vector pSCHS6 and the expressed protein was purified to apparent homogeneity by ammonium sulfate precipitation and Ni-NTA affinity column chromatography. The specific activity of the purified enzyme increased 4.7-fold with 17.5% recovery. It migrated as a single band on SDS-PAGE with an apparent molecular mass of 56kDa. The purified protein showed glucose-1-phosphate thymidylyltransferase activity, catalyzing a reversible bimolecular group transfer reaction. In the forward reaction, the highest activity was obtained with combination of dTTP and ${\alpha}-D-glucose-1-phosphate$, and only 12% of that activity was obtained with the substrates $UTP/{\alpha}-D-glucose-1-phosphate$. In the opposite direction, the purified protein was highly specific for dTDP-D-glucose and pyrophosphate.