• Korean Journal of Microbiology
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• v.25 no.3
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• pp.189-197
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• 1987

The aim of the present study was to investigate the effect of glutamate on the biosynthesis of tylosin. Activities of enzymes involved in the metabolic pathway of glutamate to form tylactone, an essential precursor of tylosin, were determined using Streptomyces fradiae grown at different concentration of glutamate. As results, it was found that cell growth and tylactone formation was controlled by the metabolic flux of oxaloacetate. It was clear that cell growth was favored by the activities of citrate synthase and aspartate aminotransferase, while the tylactone synthesis was stimulated by the activity of methylmalonyl-CoA carboxyltransferase. Therefore it was concluded that channelling of oxaloacetate was a point for favoring either cell growth or tylosin biosynthesis.

• Journal of Microbiology and Biotechnology
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• v.21 no.6
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• pp.613-616
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• 2011

Streptomyces venezuelae YJ028, bearing a deletion of the entire biosynthetic gene cluster encoding the pikromycin polyketide synthases and desosamine biosynthetic enzymes, was used as a bioconversion system for combinatorial biosynthesis of glycosylated derivatives of tylosin. Two engineered deoxysugar biosynthetic pathways for the biosynthesis of TDP-3-O-demethyl-D-chalcose or TDP-L-rhamnose in conjunction with the glycosyltransferaseauxiliary protein pair DesVII/DesVIII were expressed in a S. venezuelae YJ028 mutant strain. Supplementation of each mutant strain capable of producing TDP-3-O-demethyl-D-chalcose or TDP-L-rhamnose with tylosin aglycone tylactone resulted in the production of the 3-O-demethyl-D-chalcose, D-quinovose, or L-rhamnose-glycosylated tylactone.

• Korean Journal of Microbiology
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• v.25 no.3
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• pp.180-183
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• 1987

Stu I, type II restriction endonuclease, has been purified to homogeneity from Streptomyces tubercidicus (ATCC 25502), and its catalytic properties have been studied. For the purification of Stu I endonuclease free of nonspecific nucleases, DEAE-Sephadex (A-50), QAE-Sephadex (A-50) and Heparin-agarose column chromatography have been performed after ammonium sulfate fractionation of the crude extract. The enzyme was further purified by gel filtration using Sephadex G-100 column to obtain homogeneous form of protein. The single polypeptide species of Stu I endonuclease has a subunit molecular weight of 34,000 $\pm$ 1,000 daltons as judged by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Stu I endonuclease requires $Mg^{2+}$ ion for its activity and is maximally active at neutral pH (7.0-8.0) in the absence of NaCl.