Histidine-41 of the cytochrome b5 domain of the borage delta6 fatty acid desaturase is essential for enzyme activity.
Unlike most other plant microsomal desaturases, the Delta6-fatty acid desaturase from borage (Borago officinalis) contains an N-terminal extension that shows homology to the small hemoprotein cytochrome (Cyt) b5. To determine if this domain serves as a functional electron donor for the Delta6-fatty acid desaturase, mutagenesis and functional analysis by expression in transgenic Arabidopsis was carried out. Although expression of the wild-type borage Delta6-fatty acid desaturase resulted in the synthesis and accumulation of Delta6-unsaturated fatty acids, this was not observed in plants transformed with N-terminally deleted forms of the desaturase. Site-directed mutagenesis was used to disrupt one of the axial heme-binding residues (histidine-41) of the Cyt b5 domain; expression of this mutant form of the Delta6-desaturase in transgenic plants failed to produce Delta6-unsaturated fatty acids. These data indicate that the Cyt b5 domain of the borage Delta6-fatty acid desaturase is essential for enzymatic activity.[1]References
- Histidine-41 of the cytochrome b5 domain of the borage delta6 fatty acid desaturase is essential for enzyme activity. Sayanova, O., Shewry, P.R., Napier, J.A. Plant Physiol. (1999) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
