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. Author manuscript; available in PMC: 2009 Dec 22.

Published in final edited form as: Angew Chem Int Ed Engl. 2008;47(51):9814–9859. doi: 10.1002/anie.200801204

a) Acceptor substrate flexibility of the urdamycin GTs revealed in various Streptomyces fradiae GT mutants. Different combinations of urdamycin A (188) GTs were disrupted, resulting in the production of various glycosylated derivatives (199, 248–258) in the corresponding S. fradiae GT mutant strains. The sugar residues are color-coded to indicate which urdamycin GT is responsible for glycosyl coupling: blue – UdrGT1a, green – UrdGT1b, red – UrdGT1c, and purple – UrdGT2. b) Products isolated from Streptomyces fradiae Tü2717 upon disruption of deoxysugar biosynthetic genes. c) When expressed in glycosyltransferase-deficient mutants of the mithramycin producer Streptomyces argillaceus, UrdGT2 catalyzed production of C-glycosides (263 and 264). Heterologous expression of both UrdGT2 and the d-olivosyltransferase from the landomycin pathway of Streptomyces cyanogenus (LanGT1) in this same S. argillaceus mutant led to compound 265. Expression of UrdGT2, LanGT1, and LanGT4 in a glycosyltransferase deficient mutant of S. fradiae Tü2717, led to the production of 266.

a) Acceptor substrate flexibility of the urdamycin GTs revealed in various Streptomyces fradiae GT mutants. Different combinations of urdamycin A (188) GTs were disrupted, resulting in the production of various glycosylated derivatives (199, 248–258) in the corresponding S. fradiae GT mutant strains. The sugar residues are color-coded to indicate which urdamycin GT is responsible for glycosyl coupling: blue – UdrGT1a, green – UrdGT1b, red – UrdGT1c, and purple – UrdGT2. b) Products isolated from Streptomyces fradiae Tü2717 upon disruption of deoxysugar biosynthetic genes. c) When expressed in glycosyltransferase-deficient mutants of the mithramycin producer Streptomyces argillaceus, UrdGT2 catalyzed production of C-glycosides (263 and 264). Heterologous expression of both UrdGT2 and the d-olivosyltransferase from the landomycin pathway of Streptomyces cyanogenus (LanGT1) in this same S. argillaceus mutant led to compound 265. Expression of UrdGT2, LanGT1, and LanGT4 in a glycosyltransferase deficient mutant of S. fradiae Tü2717, led to the production of 266.