Biosynthesis of isoprenoids: crystal structure of the [4Fe-4S] cluster protein IspG.Lee, M., Grawert, T., Quitterer, F., Rohdich, F., Eppinger, J., Eisenreich, W., Bacher, A., Groll, M.
(2010) J.Mol.Biol. 404: 600-610
- PubMed: 20932974
- DOI: 10.1016/j.jmb.2010.09.050
- PubMed Abstract:
IspG protein serves as the penultimate enzyme of the recently discovered non-mevalonate pathway for the biosynthesis of the universal isoprenoid precursors, isopentenyl diphosphate and dimethylallyl diphosphate. The enzyme catalyzes the reductive rin ...
IspG protein serves as the penultimate enzyme of the recently discovered non-mevalonate pathway for the biosynthesis of the universal isoprenoid precursors, isopentenyl diphosphate and dimethylallyl diphosphate. The enzyme catalyzes the reductive ring opening of 2C-methyl-D-erythritol 2,4-cyclodiphosphate, which affords 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate. The protein was crystallized under anaerobic conditions, and its three-dimensional structure was determined to a resolution of 2.7 Å. Each subunit of the c(2) symmetric homodimer folds into two domains connected by a short linker sequence. The N-terminal domain (N domain) is an eight-stranded β barrel that belongs to the large TIM-barrel superfamily. The C-terminal domain (C domain) consists of a β sheet that is flanked on both sides by helices. One glutamate and three cysteine residues of the C domain coordinate a [4Fe-4S] cluster. Homodimer formation involves an extended contact area (about 1100 Å(2)) between helices 8 and 9 of each respective β barrel. Moreover, each C domain contacts the N domain of the partner subunit, but the interface regions are small (about 430 Å(2)). We propose that the enzyme substrate binds to the positively charged surface area at the C-terminal pole of the β barrel. The C domain carrying the iron-sulfur cluster could then move over to form a closed conformation where the substrate is sandwiched between the N domain and the C domain. This article completes the set of three-dimensional structures of the non-mevalonate pathway enzymes, which are of specific interest as potential targets for tuberculostatic and antimalarial drugs.
Lehrstuhl für Biochemie, Center for Integrated Protein Science Munich, Department Chemie, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany.