phosphomethylpyrimidine synthase activity
phosphomethylpyrimidine synthase activity
Catalysis of the reaction: 5-amino-1-(5-phospho-beta-D-ribosyl)imidazole + S-adenosyl-L-methionine = 4-amino-2-methyl-5-(phosphooxymethyl)pyrimidine + CO + 5'-deoxyadenosine + formate + L-methionine + 3 H+.