title: Evidence that the fosfomycin-producing epoxidase, HppE, is a non-heme-iron peroxidase.
abstract: The iron-dependent epoxidase HppE converts (S)-2-hydroxypropyl-1-phosphonate (S-HPP) to the antibiotic fosfomycin [(1R,2S)-epoxypropylphosphonate] in an unusual 1,3-dehydrogenation of a secondary alcohol to an epoxide. HppE has been classified as an oxidase, with proposed mechanisms differing primarily in the identity of the O2-derived iron complex that abstracts hydrogen (H•) from C1 of S-HPP to initiate epoxide ring closure. We show here that the preferred cosubstrate is actually H2O2 and that HppE therefore almost certainly uses an iron(IV)-oxo complex as the H• abstractor. Reaction with H2O2 is accelerated by bound substrate and produces fosfomycin catalytically with a stoichiometry of unity. The ability of catalase to suppress the HppE activity previously attributed to its direct utilization of O2 implies that reduction of O2 and utilization of the resultant H2O2 were actually operant.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.forename: Wei-chen
authors.initials: WC
authors.lastname: Chang
authors.forename: Yisong
authors.initials: Y
authors.lastname: Guo
authors.forename: Hui
authors.initials: H
authors.lastname: Huang
authors.forename: Spencer C
authors.initials: SC
authors.lastname: Peck
authors.forename: Maria E
authors.initials: ME
authors.lastname: Pandelia
authors.forename: Geng-min
authors.initials: GM
authors.lastname: Lin
authors.forename: Hung-wen
authors.initials: HW
authors.lastname: Liu
authors.forename: Carsten
authors.initials: C
authors.lastname: Krebs
authors.forename: J Martin
authors.initials: JM
authors.lastname: Bollinger
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D005578:Fosfomycin / Q000096:biosynthesis*; D006861:Hydrogen Peroxide / Q000737:chemistry; D019159:Nonheme Iron Proteins / Q000737:chemistry* / Q000145:classification; D010088:Oxidoreductases / Q000737:chemistry* / Q000145:classification; D010544:Peroxidases / Q000737:chemistry* / Q000145:classification; D015011:Yersinia pseudotuberculosis / Q000201:enzymology
chemical_list: D000900:Anti-Bacterial Agents; D019159:Nonheme Iron Proteins; D005578:Fosfomycin; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D010544:Peroxidases; C405402:2-hydroxypropylphosphonic acid epoxidase