Chemistry: molecular biology and microbiology – Treatment of micro-organisms or enzymes with electrical or... – Modification of viruses
Patent
1995-07-05
1997-09-16
Chereskin, Che S.
Chemistry: molecular biology and microbiology
Treatment of micro-organisms or enzymes with electrical or...
Modification of viruses
4353201, 4352523, 435325, 435419, C12N 510, C12N 1529, C12N 1563
Patent
active
056679971
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention is directed to amino acid and nucleic acid sequences and constructs, and methods related thereto.
BACKGROUND
Members of several plant families synthesize large amount of predominantly medium-chain (C8-C14) triacylglycerols in specialized storage tissues, some of which are harvested for production of important dietary or industrial medium-chain fatty acids (F. D. Gunstone, The Lipid Handbook (Chapman & Hall, New York, 1986) pp. 55-112). Laurate (C12:0), for example, is currently extracted from seeds of tropical trees at a rate approaching one million tons annually (Battey, et al., Tibtech (1989) 71:122-125).
The mechanism by which the ubiquitous long-chain fatty acid synthesis is switched to specialized medium-chain production has been the subject of speculation for many years (Harwood, Ann. Rev. Plant Physiol. Plant Mol. Biology (1988) 39:101-138). Recently, Pollard, et al., (Arch. of Biochem. and Biophys. (1991) 284:1-7) identified a medium-chain acyl-ACP thioesterase activity in developing oilseeds of California bay, Umbellularia californica. This activity appears only when the developing cotyledons become committed to the near-exclusive production of triglycerides with lauroyl (12:0) and caproyl (10:0) fatty acids. This work presented the first evidence for a mechanism for medium-chain fatty acid synthesis in plants: During elongation the fatty acids remain esterified to acyl-carrier protein (ACP). If the thioester is hydrolized prematurely, elongation is terminated by release of the medium-chain fatty acid. The Bay thioesterase was subsequently purified by Davies et al., (Arch. Biochem. Biophys. (1991) 290:37-45) which allowed the cloning of a corresponding cDNA which has been used to obtain related clones and to modify the triglyceride composition of plants (WO 91/16421 and WO 92/20236).
SUMMARY OF THE INVENTION
By this invention, further plant medium-chain thioesterases, and uses of plant long-chain thioesterase antisense sequences are provided. In addition, uses of medium-chain thioesterases from non-plant sources are considered.
In a first embodiment, this invention is directed to nucleic acid sequences which encode plant medium-chain preferring thioesterases, in particular those which demonstrate preferential activity towards fatty acyl-ACPs having a carbon chain length of C8 or C10. This includes sequences which encode biologically active plant thioesterases as well as sequences which are to be used as probes, vectors for transformation or cloning intermediates. Biologically active sequences are preferentially found in a sense orientation with respect to transcriptional regulatory regions found in various constructs. The plant thioesterase encoding sequences may encode a complete or partial sequence depending upon the intended use. The instant invention pertains to the entire or portions of the genomic sequence or cDNA sequence and to the thioesterase protein encoded thereby, including precursor or mature plant thioesterase. Plant thioesterases exemplified herein include a Cuphea hookeriana (Cuphea) and an Ulmacea (elm) thioesterase. The exemplified thioesterase sequences may also be used to obtain other similar plant thioesterases.
Of special interest are recombinant DNA constructs which can provide for the transcription or transcription and translation (expression) of the plant thioesterase sequence. In particular, constructs which are capable of transcription or transcription and translation in plant host cells are preferred. Such construct may contain a variety of regulatory regions including transcriptional initiation regions obtained from genes preferentially expressed in plant seed tissue.
In a second aspect, this invention relates to the presence of such constructs in host cells, especially plant host cells, and to a method for producing a plant thioesterase in a host cell or progeny thereof via the expression of a construct in the cell. In a related aspect, this invention includes transgenic host cells which have an expressed plant thioesteras
REFERENCES:
patent: 5512482 (1996-04-01), Voelker et al.
U.S. application No. 08/467098, Voelker et al., filed Jun. 6, 1995.
Naggert, et al (1987) Biochem. J. 243: 597-601.
Poulose, et al (1985) Journal of Biol. Chem. 260 (29); 15953-15958.
Pollard et al in The Metabolism, Structure, & Function of Plant Lipids, pp. 455-463, 1987.
Gasser, et al (Jun. 1989) Science 244: 1293-1299.
Davies Huw Maelor
Knutzon Deborah
Voelker Toni Alois
Calgene Inc.
Chereskin Che S.
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