Multicellular living organisms and unmodified parts thereof and – Method of introducing a polynucleotide molecule into or... – The polynucleotide alters fat – fatty oil – ester-type wax – or...
Reexamination Certificate
1997-09-19
2002-03-12
McElwain, Elizabeth F. (Department: 1638)
Multicellular living organisms and unmodified parts thereof and
Method of introducing a polynucleotide molecule into or...
The polynucleotide alters fat, fatty oil, ester-type wax, or...
C800S298000, C536S023200, C435S252300, C435S325000, C435S410000, C435S440000, C435S468000, C435S471000
Reexamination Certificate
active
06355861
ABSTRACT:
FIELD OF THE INVENTION
Linoleic acid (18:2) (LA) is transformed into gamma linolenic acid (18:3) (GLA) by the enzyme &Dgr;6-desaturase. When this enzyme, or the nucleic acid encoding it, is transferred into LA-producing cells, GLA is produced. The present invention provides nucleic acids comprising the &Dgr;6-desaturase gene. More specifically, the nucleic acids comprise the promoters, coding regions and termination regions of the &Dgr;6-desaturase genes. The present invention is further directed to recombinant constructions comprising a &Dgr;6-desaturase coding region in functional combination with heterologous regulatory sequences. The nucleic acids and recombinant constructions of the instant invention are useful in the production of GLA in transgenic organisms.
BACKGROUND OF THE INVENTION
Unsaturated fatty acids such as linoleic (C
18
&Dgr;
9,12
) and &agr;-linolenic (C
18
&Dgr;
9,12,15
) acids are essential dietary constituents that cannot be synthesized by vertebrates since vertebrate cells can introduce double bonds at the &Dgr;
9
position of fatty acids but cannot introduce additional double bonds between the &Dgr;
9
double bond and the methyl-terminus of the fatty acid chain. Because they are precursors of other products, linoleic and &agr;-linolenic acids are essential fatty acids, and are usually obtained from plant sources. Linoleic acid can be converted by mammals into &ggr;-linolenic acid (GLA, C
18
&Dgr;
6,9,12
) which can in turn be converted to arachidonic acid (20:4), a critically important fatty acid since it is an essential precursor of most prostaglandins.
The dietary provision of linoleic acid, by virtue of its resulting conversion to GLA and arachidonic acid, satisfies the dietary need for GLA and arachidonic acid. However, a relationship has been demonstrated between consumption of saturated fats and health risks such as hypercholesterolemia, atherosclerosis and other clinical disorders which correlate with susceptibility to coronary disease, while the consumption of unsaturated fats has been associated with decreased blood cholesterol concentration and reduced risk of atherosclerosis. The therapeutic benefits of dietary GLA may result from GLA being a precursor to arachidonic acid and thus subsequently contributing to prostaglandin synthesis. Accordingly, consumption of the more unsaturated GLA, rather than linoleic acid, has potential health benefits. However, GLA is not present in virtually any commercially grown crop plant.
Linoleic acid is converted into GLA by the enzyme &Dgr;6-desaturase. &Dgr;6-desaturase, an enzyme of more than 350 amino acids, has a membrane-bound domain and an active site for desaturation of fatty acids. When this enzyme is transferred into cells which endogenously produce linoleic acid but not GLA, GLA is produced. The present invention, by providing genes encoding &Dgr;6-desaturase, allows the production of transgenic organisms which contain functional &Dgr;6-desaturase and which produce GLA. In addition to allowing production of large amounts of GLA, the present invention provides new dietary sources of GLA.
SUMMARY OF THE INVENTION
The present invention is directed to isolated &Dgr;6-desaturase genes. Specifically, the isolated genes comprise the &Dgr;6-desaturase promoters, coding regions, and termination regions.
The present invention is further directed to expression vectors comprising the &Dgr;6-desaturase promoter, coding region and termination region.
Yet another aspect of this invention is directed to expression vectors comprising a &Dgr;6-desaturase coding region in functional combination with heterologous regulatory regions, i.e. elements not derived from the &Dgr;6-desaturase gene.
Cells and organisms comprising the vectors of the present invention, and progeny of such organisms, are also provided by the present invention.
A further aspect of the present invention provides isolated bacterial &Dgr;6-desaturase. Isolated plant a6-desaturases are also provided.
Yet another aspect of this invention provides a method for producing plants with increased gamma linolenic acid content.
A method for producing chilling tolerant plants is also provided by the present invention.
REFERENCES:
DeLuca V, AgBiotech News and Information 5 (6):225N-229N, 1993.
McElwain Elizabeth F.
Rhone-Poulenc Agrochimie
Scully Scott Murphy & Presser
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