N(6)-(pyridoxal phosphate)-L-lysyl-[4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate synthase] + L-histidyl-[4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate synthase] + 2 Fe(3+) + 4 H2O = L-lysyl-[4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate synthase] + (2S)-2-amino-5-hydroxy-4-oxopentanoyl-[4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate synthase] + 4-amino-2-methyl-5-(phosphooxymethyl)pyrimidine + 3-oxopropanoate + 2 Fe(2+) + 2 H(+) — reaction