Altering the Phosphorylation Position of Pyrophosphate-Dependent -Inositol-1-Kinase Based on Its Crystal Structure.

Most kinases utilize ATP as a phosphate donor and phosphorylate a wide range of phosphate acceptors. An alternative phosphate donor is inorganic pyrophosphate (PPi), which costs only 1/1000 of ATP. To develop a method to engineer PPi-dependent kinases, we herein aimed to alter the product of PPi-dependent -inositol kinase from d-inositol 1-phosphate to d-inositol 3-phosphate. For this purpose, we introduced the inositol recognition residues of the ATP-dependent inositol-3-kinase into the PPi-dependent -inositol-1-kinase. This replacement was expected to change the 3D arrangements of -inositol in the active site and bring the hydroxyl group at the 3C position close to the catalytic residue. LC-MS and NMR analyses proved that the engineered enzyme successfully produced inositol 3-phosphate from PPi and inositol.