My research interests fall into two main axes. First, our laboratory is investigating biochemical and molecular aspects of the sulfonation reaction in relation to plant growth, development and adaptation to stress using Arabidopsis thaliana sulfotransferases as a model system. To date, we have characterized two sulfotransferases involved in the sulfation of brassinosteroids and hydroxylated derivatives of jasmonic acid, respectively. The biochemical function and the pattern of expression of these enzymes suggest that plants like mammals use the sulfonation reaction to modulate the biological activity of hormones and chemical messengers. Our second axis of research is the study of the structure function relationship of sulfotransferases in order to elucidate the mechanism of sulfonate transfer and to define the amino acids responsible for substrate binding and catalysis. Using site-directed mutagenesis of the flavonol 3-sulfotransferase, we mapped several amino acids required for catalysis and cosubstrate binding while the construction of chimeric proteins allowed to define the domain responsible for substrate specificity.
