Biosynthesis of xanthurenic acid 8-O-beta-D-glucoside in Drosophila. Characterization of the xanthurenic acid:UDP-glucosyltransferase activity.
Xanthurenic acid 8-glucoside is a side metabolite of the tryptophan-xanthommatin pathway in Drosophila. From 3-hydroxykynurenine, two biosynthetic pathways can be envisaged, one via xanthurenic acid, and another via 3-O-glucoside of 3-hydroxykynurenine. In this report evidence is presented to show that the synthesis takes place via xanthurenic acid. (a) We have demonstrated that the Drosophila melanogaster vermilion purple mutant (unable to synthesize 3-hydroxykynurenine) synthesizes xanthurenic acid 8-glucoside when fed with xanthurenic acid; and (b) the activities required for its synthesis via xanthurenic acid have been found (3-hydroxykynurenine transaminase and xanthurenic acid:UDP-glucosyltransferase). This is the first time that a UDP-glucosyltransferase activity that utilizes xanthurenic acid has been demonstrated. The enzyme in crude extracts from Drosophila sordidula shows the following characteristics. (a) It has optimal activity at 35 degrees C at pH 7.1 (in buffer Tris-HCl), and in the presence of a divalent cation (Mg2+ or Mn2+); (b) the activity is inhibited by xanthurenic acid (above 1.5 mM), UDP, D-gluconic acid 1,5-lactone, and Triton X-100; (c) it is localized in both the microsomal and the soluble fractions; (d) the specific activity is two times higher in heads than in bodies; and (e) the activity is enhanced in flies fed with phenobarbital.
Real
M D
MD
Department of Genetics, University of Valencia, Burjassot, Spain.
Ferré
J
J
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004330:Drosophila / Q000201:enzymology*; D004331:Drosophila melanogaster / Q000201:enzymology*; D005964:Glucosyltransferases / Q000378:metabolism*; D007700:Kinetics; D008190:Lyases; D013045:Species Specificity; D000637:Transaminases / Q000378:metabolism; D014977:Xanthurenates / Q000378:metabolism*
D014977:Xanthurenates; C045676:xanthurenic acid 8-O-glucoside; D005964:Glucosyltransferases; C063902:xanthurenic acid-UDP-glucosyltransferase; D000637:Transaminases; C427605:glutamine - phenylpyruvate transaminase; C021481:kynurenine-oxoglutarate transaminase; D008190:Lyases