Histidine-41 of the Cytochrome b 5Domain of the Borage Δ6 Fatty Acid Desaturase Is Essential for Enzyme Activity
In: Plant Physiology, Jg. 121 (1999-10-01), S. 641-646
Online
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Zugriff:
Unlike most other plant microsomal desaturases, the Δ6-fatty acid desaturase from borage (Borago officinalis) contains an N-terminal extension that shows homology to the small hemoprotein cytochrome (Cyt)b 5. To determine if this domain serves as a functional electron donor for the Δ6-fatty acid desaturase, mutagenesis and functional analysis by expression in transgenic Arabidopsis was carried out. Although expression of the wild-type borage Δ6-fatty acid desaturase resulted in the synthesis and accumulation of Δ6-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 Cytb 5 domain; expression of this mutant form of the Δ6-desaturase in transgenic plants failed to produce Δ6-unsaturated fatty acids. These data indicate that the Cyt b 5 domain of the borage Δ6-fatty acid desaturase is essential for enzymatic activity.
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Histidine-41 of the Cytochrome b 5Domain of the Borage Δ6 Fatty Acid Desaturase Is Essential for Enzyme Activity
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Autor/in / Beteiligte Person: | Napier, Johnathan A. ; Sayanova, Olga ; Shewry, Peter R. |
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Zeitschrift: | Plant Physiology, Jg. 121 (1999-10-01), S. 641-646 |
Veröffentlichung: | Oxford University Press (OUP), 1999 |
Medientyp: | unknown |
ISSN: | 1532-2548 (print) ; 0032-0889 (print) |
DOI: | 10.1104/pp.121.2.641 |
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