LanGT2 Catalyzes the First Glycosylation Step during Landomycin A Biosynthesis

Abstract

The glycosyltransferase LanGT2 is involved in the biosynthesis of the hexasaccharide side chain of the angucyclic antibiotic landomycin A. Its function was elucidated by targeted gene inactivation of lanGT2. The main metabolite of the obtained mutant was identified as tetrangulol (4), the progenitor of the landomycin aglycon (7). The lack of the sugar side chain indicates that LanGT2 catalyzes the priming glycosyl transfer in the hexasaccharide biosynthesis: the attachment of a D-olivose to O-8 of the polyketide backbone. Heterologous expression of urdGT2 from S. fradiae Tü2717 in this mutant resulted in the production of a novel C-glycosylated angucycline (6).

Generation of New Landomycins with Altered Saccharide Patterns through Over‐expression of the Glycosyltransferase Gene lanGT3 in the Biosynthetic Gene Cluster of Landomycin A in Streptomyces cyanogenus S‐136

“…This provides further evidence that LanGT3 is an olivosyltransferase that catalyzes the fourth sugar attachment during biosynthesis of landomycins A, B, and J. The combination of previous studies [10,15,17,18] …”

“…While LandGT1 is responsible for the transfer of the second and fifth sugar moiety, LanGT4 transfers both rhodinoses into the third and sixth positions. [16] Most recently, LanGT2 was identified to catalyze the first glycosylation step (D-olivosyl), [17] and a targeted gene inactivation experiment on lanGT3 showed that the corresponding glycosyltransferase LanGT3 is an olivosyltransferase. [18] LanGT3 is most likely responsible for the attachment of the fourth sugar, which is the key step that distinguishes the biosyntheses of LaA and LaE.…”

Cloning and Sequencing of the Biosynthetic Gene Cluster for Saquayamycin Z and Galtamycin B and the Elucidation of the Assembly of Their Saccharide Chains

“…[12] SimB7 is a C-glycosyltransferase that is involved in simocyclinone biosynthesis, [9] and LanGT2 forms an O-glycosidic linkage during the landomycin A biosynthesis. [13] As expected, UrdGT2 was able to restore wild-type production of saquayamycin Z and galtamycin B. Surprisingly, expression of simB7 only led to the production of the monoglycosylated galtamycinone and did not restore wild-type production, which had been A C H T U N G T R E N N U N G expected.…”

“…Structure elucidation of SaqAE3: The chemical structure of SaqAE3 was elucidated with 1D NMR ( 1 H (400 MHz), 13 C (100 MHz), 1D-NOE, 1D-TOCSY)) and 2D NMR (HSQC, HMBC, 1 H-1 H COSY) spectroscopy by using a Bruker Avance DRX400. Chemical shifts are expressed in d values (ppm) by using the correspondent solvent as internal reference (CDCl 3 : d H = 7.26, s; d C = 77.0, t).…”

“…SaqAE3 showed the characteristic UV/Vis spectrum of a saquayamycin. To elucidate its structure, SaqAE3 was purified from a scaled-up fermentation and subjected to 1D ( 1 H, 13 C, NOE-1D) and 2D ( 1 H, 1 H COSY, HSQC, HMBC) NMR spectroscopy. The resulting spectra of the orange powder were compared to the assignments of saquayamycin Z as published by Strçch and co-workers.…”