Biosynthesis of colitose: expression, purification, and mechanistic characterization of GDP-4-keto-6-deoxy-D-mannose-3-dehydrase (ColD) and GDP-L-colitose synthase (ColC).

L-Colitose is a 3,6-dideoxyhexose found in the O-antigen of Gram-negative lipopolysaccharides. To study the biosynthesis of this unusual sugar, we have cloned and sequenced the L-colitose biosynthetic gene cluster from Yersinia pseudotuberculosis VI. The colD and colC genes in this cluster have been overexpressed and each gene product has been purified and characterized.

Beta-glucosylation as a part of self-resistance mechanism in methymycin/pikromycin producing strain Streptomyces venezuelae.

In our study of the biosynthesis of D-desosamine in Streptomyces venezuelae, we have cloned and sequenced the entire desosamine biosynthetic cluster. The deduced product of one of the genes, desR, in this cluster shows high sequence homology to beta-glucosidases, which catalyze the hydrolysis of the glycosidic linkages, a function not required for the biosynthesis of desosamine. Disruption of the desR gene led to the accumulation of glucosylated methymycin/neomethymycin products, all of which are biologically inactive.

The biosynthesis of GDP-L-colitose: C-3 deoxygenation is catalyzed by a unique coenzyme B6-dependent enzyme.

l-Colitose (1) is a 3,6-dideoxyhexose found in the O-antigen of gram-negative lipopoly-saccharides. While the biosynthesis of many deoxysugars have previously been investigated, l-colitose is distinct in that it originates from GDP-d-mannose. In contrast, other 3,6-dideoxyhexoses arise from CDP-d-glucose.