Catalyzes the complicated ring closure reaction between the two acyclic compounds 1-deoxy-D-xylulose-5-phosphate (DXP) and 3-amino-2-oxopropyl phosphate (1-amino-acetone-3-phosphate or AAP) to form pyridoxine 5'-phosphate (PNP) and inorganic phosphate. 1-deoxy-D-xylulose 5-phosphate + 3-amino-2-oxopropyl phosphate = H(+) + 2 H2O + phosphate + pyridoxine 5'-phosphate Cofactor biosynthesis; pyridoxine 5'-phosphate biosynthesis; pyridoxine 5'-phosphate from D-erythrose 4-phosphate: step 5/5. Homooctamer; tetramer of dimers. Belongs to the PNP synthase family.