Recent developments in the study of the structure-function relationship of flavonol sulfotransferases

With the rapid proliferation of sulfotransferase (ST) cDNA sequences in the last 5 years, consensus sequences were identified in four conserved regions. The association of these regions with substrate binding or catalysis was tested in several site-directed mutagenesis studies. Due to their strict substrate and position specificities, the flavonol 3- and 4'-STs represent an advantageous model system for the study of the structure-function relationship of cytosolic STs. Using a combination of chimeric and site-directed mutant proteins, a domain was identified containing all the determinants responsible for the substrate specificity of these enzymes, and characterized amino acid residues conserved in all cloned STs that are involved in substrate binding and catalysis. This paper summarizes the results of these studies.