| Identification of dioxygenases required for Aspergillus development. Studies of products, stereochemistry, and the reaction mechanism. | |
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MedLine Citation:
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PMID: 17906293 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Aspergillus sp. contain ppoA, ppoB, and ppoC genes, which code for fatty acid oxygenases with homology to fungal linoleate 7,8-diol synthases (7,8-LDS) and cyclooxygenases. Our objective was to identify these enzymes, as ppo gene replacements show critical developmental aberrancies in sporulation and pathogenicity in the human pathogen Aspergillus fumigatus and the genetic model Aspergillus nidulans. The PpoAs of A. fumigatus and A. nidulans were identified as (8R)-dioxygenases with hydroperoxide isomerase activity, designated 5,8-LDS. 5,8-LDS transformed 18:2n-6 to (8R)-hydroperoxyoctadecadienoic acid ((8R)-HPODE) and (5S,8R)-dihydroxy-9Z,12Z-octadecadienoic acid ((5S,8R)-DiHODE). We also detected 8,11-LDS in A. fumigatus and (10R)-dioxygenases in both Aspergilli. The diol synthases oxidized [(8R)-(2)H]18:2n-6 to (8R)-HPODE with retention of the deuterium label, suggesting antarafacial hydrogen abstraction and insertion of molecular oxygen. Experiments with stereospecifically deuterated 18:2n-6 showed that (8R)-HPODE was isomerized by 5,8- and 8,11-LDS to (5S,8R)-DiHODE and to (8R,11S)-dihydroxy-9Z,12Z-octadecadienoic acid, respectively, by suprafacial hydrogen abstraction and oxygen insertion at C-5 and C-11. PpoCs were identified as (10R)-dioxygenases, which catalyzed abstraction of the pro-S hydrogen at C-8 of 18:2n-6, double bond migration, and antafacial insertion of molecular oxygen with formation of (10R)-hydroxy-8E,12Z-hydroperoxyoctadecadienoic acid ((10R)-HPODE). Deletion of ppoA led to prominent reduction of (8R)-H(P)ODE and complete loss of (5S,8R)-DiHODE biosynthesis, whereas biosynthesis of (10R)-HPODE was unaffected. Deletion of ppoC caused biosynthesis of traces of racemic 10-HODE but did not affect the biosynthesis of other oxylipins. We conclude that ppoA of Aspergillus sp. may code for 5,8-LDS with catalytic similarities to 7,8-LDS and ppoC for linoleate (10R)-dioxygenases. Identification of these oxygenases and their products will provide tools for analyzing the biological impact of oxylipin biosynthesis in Aspergilli. |
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Authors:
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Ulrike Garscha; Fredrik Jernerén; DaWoon Chung; Nancy P Keller; Mats Hamberg; Ernst H Oliw |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. Date: 2007-09-28 |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 282 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 2007 Nov |
Date Detail:
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Created Date: 2007-11-26 Completed Date: 2008-02-04 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: United States |
Other Details:
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Languages: eng Pagination: 34707-18 Citation Subset: IM |
Affiliation:
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Department of Pharmaceutical Bioscience, Uppsala Biomedical Center, SE-75124 Uppsala, Sweden. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Aspergillus fumigatus
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metabolism,
physiology* Aspergillus nidulans / metabolism, physiology* Catalysis Chromatography, High Pressure Liquid Chromatography, Liquid / methods Dioxygenases / chemistry*, metabolism* Fatty Acids / metabolism Fungal Proteins / chemistry Mass Spectrometry / methods Models, Biological Nitrogen / chemistry Oxygen / chemistry Oxylipins / chemistry, metabolism* Phenotype Prostaglandin-Endoperoxide Synthases / metabolism Stereoisomerism Time Factors |
| Chemical | |
Reg. No./Substance:
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0/Fatty Acids; 0/Fungal Proteins; 0/Oxylipins; 7727-37-9/Nitrogen; 7782-44-7/Oxygen; EC 1.13.11.-/Dioxygenases; EC 1.14.99.1/Prostaglandin-Endoperoxide Synthases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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