Microbial transformation of validamycins.

Gene Cluster Responsible for Validamycin Biosynthesis in Streptomyces hygroscopicus subsp. jinggangensis 5008

“…Conceivably, this activity could be involved in the conversion of glucose 1-phosphate, possibly from primary metabolism, into dTDP-glucose. Incorporation of activated glucose has been proven through feeding experiments with validoxylamine A to be the final step in validamycin biosynthesis (14). Alternatively, ValB may be involved in the activation of one of the cyclitol intermediates, e.g., 1-epi-valienol 1-phosphate, to its nucleotide derivative, setting the stage for the coupling reaction that leads to a pseudodisaccharide intermediate.…”

Genetic localization and heterologous expression of validamycin biosynthetic gene cluster isolated from Streptomyces hygroscopicus var. limoneus KCCM 11405 (IFO 12704)

“…1). An early biotransformation experiment substantiated that attachment of glucose to validoxylamine A is the final step to validamycin A (Kameda et al, 1975), and the intermediacies of 2-epi-5-epi-valiolone, 5-epi-valiolone, valienone, and validone were later established by employing isotopically labeled precursors (Dong et al, 2001). The efficient incorporation of 2-epi-5-epi-valiolone and the absence of labeling with 2-epi-valiolone strongly supported that the cyclization of sedo-heptulose 7-phosphate to 2-epi-5-epi-valiolone was a committed step in the validamycin biosynthesis (Dong et al, 2001;Toyokuni et al, 1987).…”

Preparation of validoxylamine A by biotransformation of validamycin A using resting cells of a recombinant Escherichia coli

“…Many previous studies on production of validoxylamine A were based on the degradation of validamycin A by chemical-catalysis or biocatalysis (Kameda et al 1975;Jin et al 2006;Xue et al 2005;Zheng et al 2004). Figure 1 shows the reaction of transformation of validamycin A to validoxylamine A by b-glucosidase.…”