Publication Date:
2015-11-03
Description:
Many peroxy-containing secondary metabolites have been isolated and shown to provide beneficial effects to human health. Yet, the mechanisms of most endoperoxide biosyntheses are not well understood. Although endoperoxides have been suggested as key reaction intermediates in several cases, the only well-characterized endoperoxide biosynthetic enzyme is prostaglandin H synthase, a haem-containing enzyme. Fumitremorgin B endoperoxidase (FtmOx1) from Aspergillus fumigatus is the first reported alpha-ketoglutarate-dependent mononuclear non-haem iron enzyme that can catalyse an endoperoxide formation reaction. To elucidate the mechanistic details for this unique chemical transformation, we report the X-ray crystal structures of FtmOx1 and the binary complexes it forms with either the co-substrate (alpha-ketoglutarate) or the substrate (fumitremorgin B). Uniquely, after alpha-ketoglutarate has bound to the mononuclear iron centre in a bidentate fashion, the remaining open site for oxygen binding and activation is shielded from the substrate or the solvent by a tyrosine residue (Y224). Upon replacing Y224 with alanine or phenylalanine, the FtmOx1 catalysis diverts from endoperoxide formation to the more commonly observed hydroxylation. Subsequent characterizations by a combination of stopped-flow optical absorption spectroscopy and freeze-quench electron paramagnetic resonance spectroscopy support the presence of transient radical species in FtmOx1 catalysis. Our results help to unravel the novel mechanism for this endoperoxide formation reaction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yan, Wupeng -- Song, Heng -- Song, Fuhang -- Guo, Yisong -- Wu, Cheng-Hsuan -- Sae Her, Ampon -- Pu, Yi -- Wang, Shu -- Naowarojna, Nathchar -- Weitz, Andrew -- Hendrich, Michael P -- Costello, Catherine E -- Zhang, Lixin -- Liu, Pinghua -- Zhang, Yan Jessie -- P41 GM104603/GM/NIGMS NIH HHS/ -- R01 GM077387/GM/NIGMS NIH HHS/ -- R01 GM093903/GM/NIGMS NIH HHS/ -- R01 GM104896/GM/NIGMS NIH HHS/ -- England -- Nature. 2015 Nov 26;527(7579):539-43. doi: 10.1038/nature15519. Epub 2015 Nov 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA. ; Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA. ; CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China. ; Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA. ; Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, Massachusetts 02118, USA. ; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26524521" target="_blank"〉PubMed〈/a〉
Keywords:
Aspergillus fumigatus/*enzymology
;
Binding Sites
;
*Biocatalysis
;
Crystallography, X-Ray
;
Electron Spin Resonance Spectroscopy
;
Heme
;
Hydroxylation
;
Indoles/metabolism
;
Iron/metabolism
;
Ketoglutaric Acids/*metabolism
;
Oxygen/metabolism
;
Prostaglandin Endoperoxides/*biosynthesis
;
Tyrosine/metabolism
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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