Nucleotide sugars metabolism

Nucleotide sugars are a group of biochemicals that act as donors for sugar residues in the glycosylation reactions that produce polysaccharides in metabolism. They are substrates for glycosyltransferases. Various forms of these molecules exist, with GDP often being used in eukaryotes for the donation of disaccharides, such as GDP-mannose, and UDP for monosaccharides such as UDP-glucose and UDP-galactose. The nucleotide sugars are also intermediates in nucleotide sugar interconversions that produce some of the activated sugars needed for glycosylation reactions.

Nucleotide sugar metabolism is particularly well-studies in bacterial pathogens, such as E. coli and Mycobacterium tuberculosis, since these molecules are required for the synthesis of glycoconjugates on the surfaces of these organisms. These glycoconjugates are virulence factors and components of the bacterial cell wall. These pathways are also studied in plants, but here the enzymes involved are less well understood.

Since most glycosylation takes place in the endoplasmic reticulum and golgi apparatus, there are a large family of nucleotide sugar transporters that allow nucleotide sugars to move from the cytoplasm, where they are produced, into the organelles where they are consumed.