Functional Characterization of the Sulfotransferase TotS in Totopotensamide Biosynthesis

Sulfation plays important roles in various biological systems, however, tailoring modification by sulfation is relatively less common in bacterial natural products. Totopotensamide C (TPM C) was the sulfated derivative of Totopotensamide A (TPM A), a polyketide-peptide glycoside. Herein we report the genetic and biochemical characterization of TotS as a 3′-phosphoadenosine-5′-phosphosulfate (PAPS)-dependent sulfotransferase to append the sulfate to phenolic hydroxyl of TPM A to form TPM C. TotS also acts on TPM B to afford a new sulfated analogue. Key amino acid residues involved in substrate and cofactor binding of TotS were identified by homology modeling and site-directed mutagenesis. This study sets a stage to further expand the structural diversity of TPMs by sulfation.