Flavone and Flavonol Sulfotransferases

A range of ST cDNAs has been identified from functional genomics studies of A. thaliana, including one (AtST3) that has been shown to encode a flavonoid 7-ST. Unlike BFST3, AtST3 recombinant protein accepts a number of flavonol and flavone aglycones, as well as their 3-O-monosulfated derivatives.However, strict specificity to the 7-hydroxyl was found. 

The plant soluble STs have around 25 to 30% amino acid identity with mammalian soluble STs, and are of a similar size. Comparisons between F. chloraefolia F3ST and F4 ST, combined with mutational analysis and data from the crystal structure of mouse estrogen ST, have defined amino acid residues important for PAPS binding, substrate binding and catalysis, and the mechanism of sulfonate transfer. Sequence relatedness has been used to divide the STs into families and subfamilies in a similar manner as for P450s.  

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