An oleate 12-hydroxylase from Ricinus communis L. is a fatty acyl desaturase homolog
- Univ. of Kentucky, Lexington, KY (United States)
- Carnegie Institution of Washington, Stanford, CA (United States)
Recent spectroscopic evidence implicating a binuclear iron site at the reaction center of fatty acyl desaturases suggested to us that certain fatty acyl hydroxylases may share significant amino acid sequence similarity with desaturases. To test this theory, we prepared a cDNA library from developing endosperm of the castor-oil plant (Ricinus communis L.) and obtained partial nucleotide sequences for 468 anonymous clones that were not expressed at high levels in leaves, a tissue deficient in 12-hydroxyoleic acid. This resulted in the identification of several cDNA clones encoding a polypeptide of 387 amino acids with a predicted molecular weight of 44,407 and with {approx}67% sequence homology to microsomal oleate desaturase from Arabidopsis. Expression of a full-length clone under control of the cauliflower mosaic virus 35S promoter in transgenic tobacco resulted in the accumulation of low levels of 12-hydroxyoleic acid in seeds, indicating that the clone encodes the castor oleate hydroxylase. These results suggest that fatty acyl desaturases and hydroxylases share similar reaction mechanisms and provide an example of enzyme evolution. 26 refs., 6 figs., 1 tab.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-94ER20133
- OSTI ID:
- 111241
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 15 Vol. 92; ISSN PNASA6; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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