. "\"Catalysis of the reaction: (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate + H2O + 2 oxidized ferredoxin = 2-C-methyl-D-erythritol 2,4-cyclodiphosphate + 2 reduced ferredoxin.\" [EC:1.17.7.1, PMID:11752431]" . . "4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase activity" . "(E)-4-hydroxy-3-methylbut-2-en-1-yl-diphosphate:oxidized ferredoxin oxidoreductase activity" . "(E)-4-hydroxy-3-methylbut-2-enyl diphosphate synthase activity" . "1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase activity" . "1-hydroxy-2-methyl-2-butenyl 4-diphosphate synthase activity" . "EC:1.17.7.1" . "KEGG:R08689" . "MetaCyc:RXN0-882" . .