title: Inhibition of IspH, a [4Fe-4S]2+ enzyme involved in the biosynthesis of isoprenoids via the methylerythritol phosphate pathway.
abstract: The MEP pathway, which is absent in animals but present in most pathogenic bacteria, in the parasite responsible for malaria and in plant plastids, is a target for the development of antimicrobial drugs. IspH, an oxygen-sensitive [4Fe-4S] enzyme, catalyzes the last step of this pathway and converts (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate (HMBPP) into the two isoprenoid precursors: isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). A crucial step in the mechanism of this enzyme is the binding of the C4 hydroxyl of HMBPP to the unique fourth iron site in the [4Fe-4S](2+) moiety. Here, we report the synthesis and the kinetic investigations of two new extremely potent inhibitors of  E. coli  IspH where the OH group of HMBPP is replaced by an amino and a thiol group. (E)-4-Mercapto-3-methylbut-2-en-1-yl diphosphate is a reversible tight-binding inhibitor of IspH with K(i) = 20 ± 2 nM. A detailed kinetic analysis revealed that (E)-4-amino-3-methylbut-2-en-1-yl diphosphate is a reversible slow-binding inhibitor of IspH with K(i) = 54 ± 19 nM. The slow binding behavior of this inhibitor is best described by a one-step mechanism with the slow step consisting of the formation of the enzyme-inhibitor (EI) complex.
authors: Université de Strasbourg, CNRS UMR 7177, Institut Le Bel, 4 rue Blaise Pascal, CS 90032, 67081 Strasbourg Cedex, France.
authors: Karnjapan
authors: K
authors: Janthawornpong
authors: Sergiy
authors: S
authors: Krasutsky
authors: Philippe
authors: P
authors: Chaignon
authors: Michel
authors: M
authors: Rohmer
authors: C Dale
authors: CD
authors: Poulter
authors: Myriam
authors: M
authors: Seemann
mesh_terms: D055162:Biocatalysis; D053898:Biosynthetic Pathways / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D004896:Erythritol / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D010088:Oxidoreductases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013403:Sugar Phosphates / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D013729:Terpenes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; D013403:Sugar Phosphates; D013729:Terpenes; D010088:Oxidoreductases; C109866:ispH protein, E coli; D004896:Erythritol