3t0f
IspH:HMBPP (substrate) structure of the E126D mutant
Structural highlights
FunctionISPH_ECOLI Converts 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate into isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Is also involved in penicillin tolerance and control of the stringent response. Seems to directly or indirectly interact with RelA to maintain it in an inactive form during normal growth.[1] [2] [3] Publication Abstract from PubMedIsoprenoids derive from two universal precursors, isopentenyl diphosphate and dimethylallyl diphosphate, which in most human pathogens are synthesized in the deoxyxylulose phosphate pathway. The last step of this pathway is the conversion of (E)-1-hydroxy-2-methylbut-2-enyl-4-diphosphate into a mixture of isopentenyl diphosphate and dimethylallyl diphosphate catalyzed by the iron-sulfur protein IspH. The crystal structures reported here of the IspH mutant proteins T167C, E126D and E126Q reveal an alternative substrate conformation compared to the wild-type structure. Thus, the previously observed alkoxide complex decomposes, and the substrate's hydroxymethyl group rotates to interact with Glu126. The carboxyl group of Glu126 then donates a proton to the hydroxyl group to enable water elimination. The structural and functional studies provide further knowledge of the IspH reaction mechanism, which opens up new routes to inhibitor design against malaria and tuberculosis. Crystal Structures of Mutant IspH Proteins Reveal a Rotation of the Substrate's Hydroxymethyl Group during Catalysis.,Span I, Grawert T, Bacher A, Eisenreich W, Groll M J Mol Biol. 2011 Nov 23. PMID:22137895[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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