Probing the reaction mechanism of IspH protein by x-ray structure analysis

Handle URI:
http://hdl.handle.net/10754/561445
Title:
Probing the reaction mechanism of IspH protein by x-ray structure analysis
Authors:
Gräwert, Tobias; Span, Ingrid; Eisenreich, Wolfgang; Rohdich, Felix; Eppinger, Jorg ( 0000-0001-7886-7059 ) ; Bacher, Adelbert; Groll, Michael
Abstract:
Isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) represent the two central intermediates in the biosynthesis of isoprenoids. The recently discovereddeoxyxylulose 5-phosphate pathway generates a mixture of IPP and DMAPP in its final step by reductive dehydroxylation of 1-hydroxy-2-methyl- 2-butenyl 4-diphosphate. This conversion is catalyzed by IspH protein comprising a central iron-sulfur cluster as electron transfer cofactor in the active site. The five crystal structures of IspH in complex with substrate, converted substrate, products and PPi reported in this article provide unique insights into the mechanism of this enzyme. While IspH protein crystallizes with substrate bound to a [4Fe-4S] cluster, crystals of IspH in complex with IPP, DMAPP or inorganic pyrophosphate feature [3Fe-4S] clusters. The IspH:substrate complex reveals a hairpin conformation of the ligand with the C(1) hydroxyl group coordinated to the unique site in a [4Fe-4S] cluster of aconitase type. The resulting alkoxide complex is coupled to a hydrogen-bonding network, which serves as proton reservoir via a Thr167 proton relay. Prolonged x-ray irradiation leads to cleavage of the C(1)-O bond (initiated by reducing photo electrons). The data suggest a reaction mechanism involving a combination of Lewis-acid activation and proton coupled electron transfer. The resulting allyl radical intermediate can acquire a second electron via the iron-sulfur cluster. The reaction may be terminated by the transfer of a proton from the β-phosphate of the substrate to C(1) (affording DMAPP) or C(3) (affording IPP).
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division; KAUST Catalysis Center (KCC); Physical Sciences and Engineering (PSE) Division; Chemical Science Program; Biological & Organometallic Catalysis Laboratories
Publisher:
Proceedings of the National Academy of Sciences
Journal:
Proceedings of the National Academy of Sciences
Issue Date:
28-Dec-2009
DOI:
10.1073/pnas.0913045107
PubMed ID:
20080550
PubMed Central ID:
PMC2824267
Type:
Article
ISSN:
00278424
Additional Links:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824267
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC); Biological and Environmental Sciences and Engineering (BESE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorGräwert, Tobiasen
dc.contributor.authorSpan, Ingriden
dc.contributor.authorEisenreich, Wolfgangen
dc.contributor.authorRohdich, Felixen
dc.contributor.authorEppinger, Jorgen
dc.contributor.authorBacher, Adelberten
dc.contributor.authorGroll, Michaelen
dc.date.accessioned2015-08-02T09:11:30Zen
dc.date.available2015-08-02T09:11:30Zen
dc.date.issued2009-12-28en
dc.identifier.issn00278424en
dc.identifier.pmid20080550en
dc.identifier.doi10.1073/pnas.0913045107en
dc.identifier.urihttp://hdl.handle.net/10754/561445en
dc.description.abstractIsopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) represent the two central intermediates in the biosynthesis of isoprenoids. The recently discovereddeoxyxylulose 5-phosphate pathway generates a mixture of IPP and DMAPP in its final step by reductive dehydroxylation of 1-hydroxy-2-methyl- 2-butenyl 4-diphosphate. This conversion is catalyzed by IspH protein comprising a central iron-sulfur cluster as electron transfer cofactor in the active site. The five crystal structures of IspH in complex with substrate, converted substrate, products and PPi reported in this article provide unique insights into the mechanism of this enzyme. While IspH protein crystallizes with substrate bound to a [4Fe-4S] cluster, crystals of IspH in complex with IPP, DMAPP or inorganic pyrophosphate feature [3Fe-4S] clusters. The IspH:substrate complex reveals a hairpin conformation of the ligand with the C(1) hydroxyl group coordinated to the unique site in a [4Fe-4S] cluster of aconitase type. The resulting alkoxide complex is coupled to a hydrogen-bonding network, which serves as proton reservoir via a Thr167 proton relay. Prolonged x-ray irradiation leads to cleavage of the C(1)-O bond (initiated by reducing photo electrons). The data suggest a reaction mechanism involving a combination of Lewis-acid activation and proton coupled electron transfer. The resulting allyl radical intermediate can acquire a second electron via the iron-sulfur cluster. The reaction may be terminated by the transfer of a proton from the β-phosphate of the substrate to C(1) (affording DMAPP) or C(3) (affording IPP).en
dc.publisherProceedings of the National Academy of Sciencesen
dc.relation.urlhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824267en
dc.subjectIron-sulfur proteinen
dc.subjectIsoprenoid biosynthesisen
dc.subjectLytB proteinen
dc.subjectNonmevalonate pathwayen
dc.subjectTerpene biosynthesisen
dc.titleProbing the reaction mechanism of IspH protein by x-ray structure analysisen
dc.typeArticleen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentChemical Science Programen
dc.contributor.departmentBiological & Organometallic Catalysis Laboratoriesen
dc.identifier.journalProceedings of the National Academy of Sciencesen
dc.identifier.pmcidPMC2824267en
dc.contributor.institutionCenter for Integrated Protein Science, Department Chemie, Lehrstuhl für Biochemie, Technische Universität München, Lichtenbergstrasse 4, Garching, Germanyen
dc.contributor.institutionMerck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germanyen
kaust.authorEppinger, Jorgen

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