Document Detail

PpoC from Aspergillus nidulans is a fusion protein with only one active haem.
MedLine Citation:
PMID:  19878096     Owner:  NLM     Status:  MEDLINE    
In Aspergillus nidulans Ppos [psi (precocious sexual inducer)-producing oxygenases] are required for the production of so-called psi factors, compounds that control the balance between the sexual and asexual life cycle of the fungus. The genome of A. nidulans harbours three different ppo genes: ppoA, ppoB and ppoC. For all three enzymes two different haem-containing domains are predicted: a fatty acid haem peroxidase/dioxygenase domain in the N-terminal region and a P450 haem-thiolate domain in the C-terminal region. Whereas PpoA was shown to use both haem domains for its bifunctional catalytic activity (linoleic acid 8-dioxygenation and 8-hydroperoxide isomerization), we found that PpoC apparently only harbours a functional haem peroxidase/dioxygenase domain. Consequently, we observed that PpoC catalyses mainly the dioxygenation of linoleic acid (18:2Delta9Z,12Z), yielding 10-HPODE (10-hydroperoxyoctadecadienoic acid). No isomerase activity was detected. Additionally, 10-HPODE was converted at lower rates into 10-KODE (10-keto-octadecadienoic acid) and 10-HODE (10-hydroxyoctadecadienoic acid). In parallel, decomposition of 10-HPODE into 10-ODA (10-octadecynoic acid) and volatile C-8 alcohols that are, among other things, responsible for the characteristic mushroom flavour. Besides these principle differences we also found that PpoA and PpoC can convert 8-HPODE and 10-HPODE into the respective epoxy alcohols: 12,13-epoxy-8-HOME (where HOME is hydroxyoctadecenoic acid) and 12,13-epoxy-10-HOME. By using site-directed mutagenesis we demonstrated that both enzymes share a similar mechanism for the oxidation of 18:2Delta9Z,12Z; they both use a conserved tyrosine residue for catalysis and the directed oxygenation at the C-8 and C-10 is most likely controlled by conserved valine/leucine residues in the dioxygenase domain.
Florian Brodhun; Stefan Schneider; Cornelia G?bel; Ellen Hornung; Ivo Feussner
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-01-15
Journal Detail:
Title:  The Biochemical journal     Volume:  425     ISSN:  1470-8728     ISO Abbreviation:  Biochem. J.     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-14     Completed Date:  2010-02-09     Revised Date:  2010-03-08    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  England    
Other Details:
Languages:  eng     Pagination:  553-65     Citation Subset:  IM    
Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Justus-von-Liebig-Weg 11, D-37077 G?ttingen, Germany.
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MeSH Terms
Alcohols / chemistry
Aspergillus nidulans / metabolism*
Catalytic Domain
Cloning, Molecular
Dioxygenases / chemistry*,  genetics
Fatty Acids / chemistry
Fungal Proteins / metabolism*
Genome, Fungal
Heme / chemistry*
Linoleic Acid / chemistry
Linoleic Acids / chemistry
Mutagenesis, Site-Directed
Oxylipins / chemistry
Protein Structure, Tertiary
Reg. No./Substance:
0/Alcohols; 0/Fatty Acids; 0/Fungal Proteins; 0/Linoleic Acids; 0/Oxylipins; 14875-96-8/Heme; 2197-37-7/Linoleic Acid; 90540-32-2/10-hydroperoxy-8,12-octadecadienoic acid; EC 1.13.11.-/Dioxygenases

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