Mg 2+ -Triggered and Ph-Tuned in Vitro Assembly of Trehalose-6-Phosphate Synthase

The enzyme OtsA (trehalose-P synthase) plays a critical role in the biosynthesis of trehalose, which is a nonreducing disaccharide that plays important functions in many organisms. By using light scattering technique, we discovered that OtsA in Arthrobacter strain A3 polymerized in the presence of divalent metal ions (Mg2+ or Ca2+), and the kinetics of the assembly was dependent on their concentrations. We identified potential compounds that can affect the kinetics of the polymerization, particularly, heparin, which acts as a very promising inhibitor of the polymerization. The OtsA assembly turns out to be a very delicate process that is finely regulated by pH. OtsA may be in the polymerized form at physiological pH in vivo, suggesting a more complicated mechanism of the enzyme. These unique properties of OtsA provide novel insights into the molecular mechanism of the biosynthesis of trehalose.