Discontinuous fatty acid elongation yields hydroxylated seed oil with improved function.

The biosynthesis of 'unusual' fatty acids with structures that deviate from the common C16 and C18 fatty acids has evolved numerous times in the plant kingdom. Characterization of unusual fatty acid biosynthesis has enabled increased understanding of enzyme substrate properties, metabolic plasticity and oil functionality. Here, we report the identification of a novel pathway for hydroxy fatty acid biosynthesis based on the serendipitous discovery of two C24 fatty acids containing hydroxyl groups at the 7 and 18 carbon atoms as major components of the seed oil of Orychophragmus violaceus, a China-native Brassicaceae. Biochemical and genetic evidence are presented for premature or 'discontinuous' elongation of a 3-OH intermediate by a divergent 3-ketoacyl-CoA (coenzyme A) synthase during a chain extension cycle as the origin of the 7-OH group of the dihydroxy fatty acids. Tribology studies revealed superior high-temperature lubricant properties for O. violaceus seed oil compared to castor oil, a high-performance vegetable oil lubricant. These findings provide a direct pathway for designing a new class of environmentally friendly lubricants and unveil the potential of O. violaceus as a new industrial oilseed crop.

Solid-state NMR spectroscopic studies of an integral membrane protein inserted into aligned phospholipid bilayer nanotube arrays.

This communication demonstrates for the first time that solid-state NMR spectroscopic studies can be used to investigate aligned phospholipid bilayer nanotube arrays. Also, an integral membrane peptide can be successfully incorporated into the oriented phospholipid bilayer nanotube arrays and studied with 2H solid-state NMR spectroscopy.

Fungal responsive fatty acid acetylenases occur widely in evolutionarily distant plant families.

The fungal elicitor-induced ELI12 gene from parsley has been previously shown to encode a divergent form of the Delta12-oleic acid desaturase. In this report, we show that the ELI12 gene product is a fatty acid acetylenase or a triple-bond-forming enzyme. Expression of this enzyme in transgenic soybean seeds was accompanied by the accumulation of the Delta12-acetylenic fatty acids, crepenynic and dehydrocrepenynic acids. Using PCR with degenerate oligonucleotides, we also show that homologs of the ELI12 gene are present in other members of the Apiaceae family. In addition, cDNAs for divergent forms of the Delta12-oleic acid desaturase were detected among the expressed sequence tags (ESTs) from English ivy, an Araliaceae species, and sunflower, an Asteraceae species. As with the ELI12 gene, expression of these cDNAs in transgenic soybean embryos was accompanied by the accumulation of crepenynic and dehydrocrepenynic acids. Homologs of the sunflower acetylenase gene were also detected in other Asteraceae species, as revealed by PCR analysis of isolated genomic DNA. Results from Northern blot and EST analyses indicated that the expression of the sunflower gene, like ELI12, was induced by fungal elicitation. Overall, these results demonstrate that expressed genes for Delta12-fatty acid acetylenases occur in at least three plant families, and are responsive to fungal pathogenesis. Natural products derived from crepenynic and dehydrocrepenynic acids that display antifungal, insecticidal, and nematicidal properties are distributed through at least 15 plant families. The acetylenases described here provide probes for chemotaxonomists, and facilitate functional genomic and molecular investigations of these defensive mechanisms.