Structural Characterization of Landomycin O- and C-Glycosyltransferases

Hochschulschrift

Zusammenfassung: LanGT2 is the O-glycosyltransferase (O-GT) that catalyzes the first D-olivose attachment on the polyketide aglycone with glycosidic C-O bond formation in landomcyin A biosynthesis while UrdGT2 is the C-glycosyltransferase (C-GT) that catalyzes the formation of a C-C bond between the polyketide aglycone and D-olivose in urdamycin A biosynthesis. Both proteins are classified as the GT1 family and share a significant 53% protein sequence homology. Swapping only 10 residues of O-GT LanGT2 and C-GT UrdGT2 and an additional substitution of S8 to A8 creates a mutant protein, LanGT2S8Ac, a C-GT to catalyze the C-C bond formation in vivo. Crystal structures of both O-GT LanGT2 and C-GT LanGT2S8Ac as well as TDP-carba-D-olivose or TDP-bound structures have been determined by X-ray diffraction to 1.9-2.3 Å resolution. The sugar nucleotide donor binds in the C-terminal domain of O-GT LanGT2 and C-GT LanGT2S8Ac with a similar binding mode, in which the carba-D-olivose is oriented towards the interdomain cleft. Conformational changes of highly flexible helices α8a and α8b are observed during the binding of nucleotide sugar donor and after glycosyltransfer of the D-olivose. Helices α8a and α8b are poorly defined in apo-structures and become stabilized through the recognition of the carba-Dolivose moiety of TDP-carba-D-olivose. After glycosyltransfer of the D-olivose moiety in the TDP-bound protein, helices α8a and α8b become mobile to allow the release of negatively charged thymidine diphosphate. Molecular docking of the aglycone substrate, 11-deoxylandomcyinone and tetrangulol in LanGT2 and LanGT2S8Ac illustrated that the aglycone binds in the N-terminal domain and provides a mechanistic basis for divergent Oand C-glycosylation, respectively. The docking models suggest that D137 acts as a catalytic base to abstract a proton from the C8-OH group of aglycone, where the orientation of the Oor C-nucleophile in relation to the sugar nucleotide is anticipated to distinguish O- versus Cglycosylation. These results may provide a blueprint for the rational design of novel GTs with increased substrate promiscuity and/or divergent catalytic mechanisms

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Albert-Ludwigs-Universität Freiburg, Dissertation, 2013

Classification and Topics

• Keyword: Glycosyltransferasen ; Friedel-Crafts-Reaktion ; Arzneimittelentwicklung ; Arzneimitteldesign

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2015
• Creator: Tam, Heng Keat
• Contributor: Einsle, Oliver

Further information

• DOI: 10.6094/UNIFR/10119
• URN: urn:nbn:de:bsz:25-freidok-101195
• Rights: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2025, 1:43 PM CET