Glycosyltransferases in secondary plant metabolism: tranquilizers and stimulant controllers

Abstract

Plants are exposed to a wide range of toxic and bioactive low-molecular-weight molecules from both exogenous and endogenous sources. Glycosylation is one of the primary sedative mechanisms that plants utilise in order to maintain metabolic homeostasis. Recently, a range of glycosyltransferases has been characterized in detail with regard to substrate specificity. The next step in increasing our understanding of the biology of glycosylation will require information regarding the exact role of individual glycosyltransferases in planta, as well as an insight into their potential involvement in metabolon-complexes. Hopefully, this will answer how a large number of glycosyltransferases with broad, rather than narrow, substrate specificity can be constrained in order to avoid interfering with other pathways of primary and secondary metabolism. These and other topics are discussed.

Cloning and characterization of a glucosyltransferase that reacts on 7-hydroxyl group of flavonol and 3-hydroxyl group of coumarin from tobacco cells

“…Recently, many GTase genes have been isolated from diverse plant species, and they could be classified into some gene families based on their amino acid sequences [5].…”

“…Such glycosylation reactions are catalyzed by glycosyltransferases (GTases). To date, many genes encoding GTases that catalyze mainly hydroxyl groups or carboxyl groups of secondary products were isolated from several plants (for review, [4,5]). Plant GTases are highly conserved in their C-terminus, named the PSPG box (plant secondary product glucosyltransferase signature, [6]), forming a super-gene family.…”

Detoxification of the Fusarium Mycotoxin Deoxynivalenol by a UDP-glucosyltransferase from Arabidopsis thaliana

“…The attached sugar blocks the reactive site of the substance and consequently reduces toxicity for the plant. Furthermore such modifications are thought to provide access to membrane-bound transporters, thus opening exit pathways from the cytosol to, for example, the cell wall or the vacuole (46).…”

Recombinant expression and functional characterisation of regiospecific flavonoid glucosyltransferases from Hieracium pilosella L.

“…(Haag-Berrurier and Duquénois 1963;Zidorn et al 2002Zidorn et al , 2005. Glycosylation generally leads to reduced chemical reactivity and enhanced water solubility of secondary metabolites, facilitating their transport and storage (Jones and Vogt 2001). The transfer of a sugar moiety from an activated donor to an acceptor molecule is generally catalysed by members of the superfamily of glycosyltransferases (GTs).…”