Grant: Discovery Grants Program - Individual

Sulfotransferases (STs) catalyze the transfer of a sulfuryl group (SO3) from the universal donor 3'-phosphoadenosine 5'-phosphosulfate to a hydroxyl group of various substrates in a process called the sulfonation reaction. These enzymes share highly conserved amino acid sequence regions across all kingdoms; however, their substrates and physiological function are very diverse. In mammals, the sulfonation reaction is involved in mechanisms of cellular detoxification and in the modulation of the biological activity of steroid hormones and neurotransmitters. In plants, few STs have been characterized despite the large number of sequences found in databases. Understanding of their role in plant biology is still relatively speculative. Since the cloning of the first plant ST cDNA more than ten years ago from Flaveria chloraefolia, functional genomic approaches, particularly in Arabidopsis thaliana, have led to the characterization of brassinosteroid, hydroxyjasmonate, desulfoglucosinolate and flavonoid STs. However, these efforts are hindered by a limited knowledge of plant sulfated metabolites. The long term objective of our research program is to elucidate the biological function of the 17 sulfotransferase-coding genes present in the genome of Arabidopsis thaliana. The specific objectives of the present proposal are to identify the structure of the sulfated metabolites of Arabidospsis thaliana, to characterize the biological function of five of the 10-STs that remain to be characterized and to elucidate the role of the sulfonation of 12-hydroxyjasmonate in the control of flowering time and anther development using Arabidopsis thaliana and Nicotiana tobacum as experimental systems.