Structural Characterization of a Heterogalactan from Antler-shaped Ganoderma lucidum

Abstract

The family of glycosyltransferases includes hundreds of proteins, most of which are using NDP-sugar as one of the substrates. In order to serve as a glycosyl donor, a sugar or a sugar derivative (e.g. GlcA) needs to be “activated” to a highly energetic state of a nucleotide-sugar. This activation requires the involvement of specific enzymes which attach NDP (or, in one case, NMP) to a given sugar, using NTP or NDP as substrate. The present review provides concise survey of distinct plant nucleotide- sugar pyrophosphorylases (all using NTP as one of the substrates and differing in sugar specificity) as well as nucleotide-sugar phosphorylases and sucrose synthase (all using NDP as one of substrates). The pyrophosphorylases discussed include UGPase, USPase, UAGPase, AGPase, GMPase (VTC1) and FKGP, whereas phosphorylases include ADP- Glc phosphorylase and GDP-Gal phosphorylase (VTC2/VTC5). We also discuss the activation mechanism of 3-deoxy-D-manno-octulosonic acid (Kdo) by CKS, leading to the formation of a unique NMP-linked sugar (CMP-Kdo).