Functional cloning and characterization of a UDP-glucuronic acid decarboxylase: The pathogenic fungus Cryptococcus neoformans elucidates UDP-xylose synthesis

Maor Bar-Peled, Cara L. Griffith, Tamara L. Doering

Research output: Contribution to journalArticle

117 Scopus citations

Abstract

UDP-xylose is a sugar donor required for the synthesis of diverse and important glycan structures in animals, plants, fungi, and bacteria. Xylose-containing glycans are particularly abundant in plants and in the polysaccharide capsule that is the major virulence factor of the pathogenic fungus Cryptococcus neoformans. Biosynthesis of UDP-xylose is mediated by UDP-glucuronic acid decarboxylase, which converts UDP-glucuronic acid to UDP-xylose. Although this enzymatic activity was described over 40 years ago it has never been fully purified, and the gene encoding it has not been identified. We used homology to a bacterial gene, hypothesized to encode a related function, to identify a cryptococcal sequence as putatively encoding a UDP-glucuronic acid decarboxylase. A soluble 47-kDa protein derived from bacteria expressing the C. neoformans gene catalyzed conversion of UDP-glucuronic acid to UDP-xylose, as confirmed by NMR analysis. NADH, UDP, and UDP-xylose inhibit the activity. Close homologs of the cryptococcal gene, which we termed UXS1, appear in genome sequence data from organisms ranging from bacteria to humans.

Original languageEnglish
Pages (from-to)12003-12008
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume98
Issue number21
DOIs
StatePublished - Oct 9 2001

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