Arabidopsis Glycosyltransferase Family 1

Glycosyl transferases (GTs) catalyze the addition of a sugar group to target molecules by the formation of a glycosidic bond. Glycosylation serves to change the stability and solubility of molecules. In plants, GTs are involved in biosynthesis of secondary metabolites, and in the detoxification of xenobiotics.

The UDP-dependent glycosyl transferases (UGTs) use a UDP activated sugar as the sugar donor and glycosylate a variety of compounds. They belong to the Glycosyltransferase Family 1, and contain the UGT C-terminal consensus sequence as presented in Mackenzie et al. 1997:

[F/V/A]-[L/I/V/M/F]-[T/S]-[H/Q]-[S/G/A/C]-GXX-[S/T/G]-XX-[D/E]-XXXXXXP-[L/I/V/M/F/A]-XX-P-[L/M/V/F/I/Q]-XX-[D/E]-Q

To date, the GT tertiary structures solved all adopt one of two conformations: the GT-A fold or the GT-B fold. Two different catalytic mechanisms have been described for each fold, referred to as retaining and inverting. At this time, UGTs have been observed to be inverting and to adopt the GT-B fold. The precise nature of the UGT reaction mechanism is not thoroughly established, but it is proposed to occur as described in the image below.

(Click for a larger version.)

In the Cyanogenic Glucoside & Molecular Evolution Research Group, we focus on UGT substrate specificity, as well as the ability of in particular Sorghum UGT85B1 to assemble into a metabolon with the two cytochromes P450 from the dhurrin biosynthetic pathway.

Sequences

Arabidopsis

available as