Identification and functional characterization of the moss Physcomitrella patens Δ5-desaturase gene involved in arachidonic and eicosapentaenoic acid biosynthesis

Songsri Kaewsuwan, Edgar B. Cahoon, Pierre François Perroud, Chanpen Wiwat, Nathinee Panvisavas, Ralph S. Quatrano, David J. Cove, Nuntavan Bunyapraphatsara

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34 Scopus citations


The moss Physcomitrella patens contains high levels of arachidonic acid and lesser amounts of eicosapentaenoic acid. Here we report the identification and characterization of a Δ5-desaturase from P. patens that is associated with the synthesis of these fatty acids. A full-length cDNA for this desaturase was identified by data base searches based on homology to sequences of known Δ5-desaturase cDNAs from fungal and algal species. The resulting P. patens cDNA encodes a 480-amino acid polypeptide that contains a predicted N-terminal cytochrome b5-like domain as well as three histidine-rich domains. Expression of the enzyme in Saccharomyces cerevisiae resulted in the production of the Δ5-containing fatty acid arachidonic acid in cells that were provided di-homo-γ-linolenic acid. In addition, the expressed enzyme generated Δ5-desaturation products with the C20 substrates ω-6 eicosadienoic and ω-3 eicosatrienoic acids, but no products were detected with the C18 fatty acid linoleic and α-linolenic acids or with the C22 fatty acid adrenic and docosapentaenoic acids. When the corresponding P. patens genomic sequence was disrupted by replacement through homologous recombination, a dramatic alteration in the fatty acid composition was observed, i.e. an increase in di-homo-γ-linolenic and eicosatetraenoic acids accompanied by a concomitant disappearance of the Δ5-fatty acid arachidonic and eicosapentaenoic acids. In addition, overexpression of the P. patens cDNA in protoplasts isolated from a disrupted line resulted in the restoration of arachidonic acid synthesis.

Original languageEnglish (US)
Pages (from-to)21988-21997
Number of pages10
JournalJournal of Biological Chemistry
Issue number31
StatePublished - Aug 4 2006
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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