title: Crystal structures of mutant IspH proteins reveal a rotation of the substrate's hydroxymethyl group during catalysis.
abstract: Isoprenoids 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.
authors.affiliation: Chemistry Department, Center for Integrated Protein Science, Chair of Biochemistry, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Span
authors.forename: Tobias
authors.initials: T
authors.lastname: Gräwert
authors.forename: Adelbert
authors.initials: A
authors.lastname: Bacher
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eisenreich
authors.forename: Michael
authors.initials: M
authors.lastname: Groll
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray / Q000379:methods; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D045782:Hemiterpenes / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism; D050505:Mutant Proteins / Q000737:chemistry* / Q000378:metabolism*; D010755:Organophosphates / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013729:Terpenes / Q000737:chemistry; D014867:Water
chemical_list: C467061:4-hydroxy-3-methyl-2-butenyl diphosphate; D029968:Escherichia coli Proteins; D045782:Hemiterpenes; D007506:Iron-Sulfur Proteins; D050505:Mutant Proteins; D010755:Organophosphates; D009943:Organophosphorus Compounds; D013729:Terpenes; D014867:Water; C004809:isopentenyl pyrophosphate; C043060:3,3-dimethylallyl pyrophosphate; D010088:Oxidoreductases; C109866:ispH protein, E coli