IUBMB Enzyme Nomenclature


Accepted name: (E)-4-hydroxy-3-methylbut-2-enyl-diphosphate synthase (flavodoxin)

Reaction: (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate + H2O + oxidized flavodoxin = 2-C-methyl-D-erythritol 2,4-cyclodiphosphate + reduced flavodoxin

For diagram of reaction click here.

Other name(s): 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase (ambiguous); (E)-4-hydroxy-3-methylbut-2-en-1-yl-diphosphate:protein-disulfide oxidoreductase (hydrating) (incorrect); (E)-4-hydroxy-3-methylbut-2-enyl diphosphate synthase (ambiguous); ispG (gene name)

Systematic name: (E)-4-hydroxy-3-methylbut-2-en-1-yl-diphosphate:oxidized flavodoxin oxidoreductase

Comments: A bacterial iron-sulfur protein that contains a [4Fe-4S] cluster. Forms part of an alternative non-mevalonate pathway for isoprenoid biosynthesis that is found in most bacteria. Plants and cyanobacteria have a similar enzyme that utilizes ferredoxin rather than flavodoxin (cf. EC

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Hecht, S., Eisenreich, W., Adam, P., Amslinger, S., Kis, K., Bacher, A., Arigoni, D. and Rohdich, F. Studies on the nonmevalonate pathway to terpenes: the role of the GcpE (IspG) protein. Proc. Natl. Acad. Sci. USA 98 (2001) 14837-14842. [PMID: 11752431]

2. Zepeck, F., Grawert, T., Kaiser, J., Schramek, N., Eisenreich, W., Bacher, A. and Rohdich, F. Biosynthesis of isoprenoids. purification and properties of IspG protein from Escherichia coli. J. Org. Chem. 70 (2005) 9168-9174. [PMID: 16268586]

3. Puan, K.J., Wang, H., Dairi, T., Kuzuyama, T. and Morita, C.T. fldA is an essential gene required in the 2-C-methyl-D-erythritol 4-phosphate pathway for isoprenoid biosynthesis. FEBS Lett 579 (2005) 3802-3806. [PMID: 15978585]

[EC created 2014]

Return to EC 1.17.7 home page
Return to EC 1.17 home page
Return to EC 1 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page