Catalytic analysis of the validamycin glycosyltransferase (ValG) and enzymatic production of 4''-epi-validamycin A.

ABSTRACT: ValG is a glycosyltransferase (GT) that is responsible for the glucosylation of validoxylamine A to validamycin A. To explore the potential utilization of ValG as a tool for the production of validamycin analogues, a number of nucleotidyldiphosphate-sugars were evaluated as alternative substrates for ValG. The results indicated that in addition to its natural substrate, UDP-glucose, ValG also efficiently utilized UDP-galactose as sugar donor and resulted in the production of an unnatural compound, 4''-epi-validamycin A. The new compound demonstrated a moderate growth inhibitory activity against the plant fungal pathogen Rhizoctonia solani (= Pellicularia sasakii). A comparative analysis of ValG with its homologous proteins revealed that ValG contains an unusual DTG motif, in place of the D

SUBMITTER: Xu H 

PROVIDER: S-EPMC2574543 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature