Document Detail

Two aerobic pathways for the formation of unsaturated fatty acids in Pseudomonas aeruginosa.
MedLine Citation:
PMID:  16573679     Owner:  NLM     Status:  MEDLINE    
The double bond in anaerobic unsaturated fatty acid (UFA) biosynthesis is introduced by the FabA dehydratase/isomerase of the bacterial type II fatty acid biosynthetic pathway. A DeltafabA mutant of Pseudomonas aeruginosa grew aerobically, but required a UFA supplement for anaerobic growth. Wild-type cells produced 18:1Delta11 as the principal UFA, whereas the DeltafabA strain produced only 16:1Delta9. The double bond in the 16:1Delta9 was introduced after phospholipid formation and was localized in the sn-2 position. Two predicted membrane proteins, DesA and DesB, possessed the conserved histidine clusters characteristic of fatty acid desaturases. The DeltafabADeltadesA double mutant required exogenous fatty acids for growth but the DeltafabAdesB double mutant did not. Exogenous stearate was converted to 18:1Delta9 and supported the growth of DeltafabADeltadesA double mutant. A DeltafabADeltadesAdesB triple mutant was unable to desaturate exogenous stearate and was an UFA auxotroph. We detected a 2.5-fold increase in desA expression in DeltafabA mutants, whereas desB expression was derepressed by the deletion of the gene encoding a transcriptional repressor DesT. These data add two aerobic desaturases to the enzymes used for fatty acid metabolism in proteobacteria: DesA, a 2-position phospholipid Delta9-desaturase that supplements the anaerobic FabA pathway, and DesB, an inducible acyl-CoA Delta9-desaturase whose expression is repressed by DesT.
Kun Zhu; Kyoung-Hee Choi; Herbert P Schweizer; Charles O Rock; Yong-Mei Zhang
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular microbiology     Volume:  60     ISSN:  0950-382X     ISO Abbreviation:  Mol. Microbiol.     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-03-31     Completed Date:  2006-06-27     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  8712028     Medline TA:  Mol Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  260-73     Citation Subset:  IM    
Department of Infectious Diseases, Protein Science Division, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
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MeSH Terms
Aerobiosis / genetics
Amino Acid Sequence
Cell Membrane / enzymology
Fatty Acids, Unsaturated / biosynthesis*,  genetics
Gene Deletion
Gene Expression Regulation, Bacterial
Genes, Bacterial
Hydro-Lyases / genetics
Membrane Proteins / genetics,  metabolism*
Molecular Sequence Data
Multigene Family
Pseudomonas aeruginosa / enzymology*,  genetics
Stearates / metabolism
Stearoyl-CoA Desaturase / genetics,  metabolism*
Substrate Specificity
Grant Support
Reg. No./Substance:
0/Fatty Acids, Unsaturated; 0/Membrane Proteins; 0/Stearates; EC Desaturase; EC 4.2.1.-/Hydro-Lyases
Comment In:
Mol Microbiol. 2006 Apr;60(2):256-9   [PMID:  16573678 ]

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