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The Fatty Acid 8,11-Diol Synthase of Aspergillus fumigatus is Inhibited by Imidazole Derivatives and Unrelated to PpoB.
MedLine Citation:
PMID:  22544380     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
(8R)-Hydroperoxy-(9Z,12Z)-octadecadienoic acid (8-HPODE) is formed by aspergilli as an intermediate in biosynthesis of oxylipins with effects on sporulation. 8-HPODE is transformed by separate diol synthases to (5S,8R)-dihydroxy- and (8R,11S)-dihydroxy-(9Z,12Z)-octadecadienoic acids (5,8- and 8,11-DiHODE). The former is formed by the cytochrome P450 (P450) domain of 5,8-linoleate diol synthase (5,8-LDS or PpoA). Our aim was to characterize the 8,11-diol synthase of Aspergillus fumigatus, which is prominent in many strains. The 8,11-diol synthase was soluble and had a larger molecular size (>100 kDa) than most P450. Miconazole, ketoconazole, and 1-benzylimidazole, classical inhibitors of P450, reduced the biosynthesis of 8,11-DiHODE from 8-HPODE (apparent IC(50) values ~0.8, ~5, and ~0.6 μM, respectively), but did not inhibit the biosynthesis of 5,8-DiHODE. Analysis of hydroperoxides of regioisomeric C(18) and C(20) fatty acids showed that the 8,11-diol synthase was specific for certain hydroperoxides with R configuration. The suprafacial hydrogen abstraction and oxygen insertion at C-11 of 8-HPODE was associated with a small deuterium kinetic isotope effect ((H) k (cat)/(D) k (cat) ~1.5), consistent with P450-catalyzed oxidation. The genome of A. fumigatus contains over 70 P450 sequences. The reaction mechanism, size, and solubility of 8,11-diol synthase pointed to PpoB, a homologue of 5,8-LDS, as a possible candidate of this activity. Gene deletion of ppoB of A. fumigatus strains AF:∆ku80 and J272 did not inhibit biosynthesis of 8,11-DiHODE and recombinant PpoB appeared to lack diol synthase activity. We conclude that 8,11-DiHODE is formed from 8-HPODE by a soluble and substrate-specific 8,11-diol synthase with catalytic characteristics of class III P450.
Authors:
Fredrik Jernerén; Ernst H Oliw
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-4-28
Journal Detail:
Title:  Lipids     Volume:  -     ISSN:  1558-9307     ISO Abbreviation:  -     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-4-30     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0060450     Medline TA:  Lipids     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Pharmaceutical Biosciences, Uppsala Biomedical Center, Uppsala University, 75124, Uppsala, Sweden.
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