Multicellular living organisms and unmodified parts thereof and – Method of introducing a polynucleotide molecule into or... – The polynucleotide alters carbohydrate production in the plant
Reexamination Certificate
1999-12-08
2002-11-19
Fox, David T. (Department: 1638)
Multicellular living organisms and unmodified parts thereof and
Method of introducing a polynucleotide molecule into or...
The polynucleotide alters carbohydrate production in the plant
C800S278000, C800S286000, C800S317200, C435S320100, C435S419000, C536S023600, C536S024500
Reexamination Certificate
active
06483009
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national stage filing of PCT/IB98/00270, filed on Feb. 23, 1998, under 35 U.S.C. §371.
FIELD OF THE INVENTION
The present invention relates to a method of inhibiting gene expression, particularly inhibiting gene expression in a plant. The present invention also relates to a nucleotide sequence useful in the method. In addition, the present invention relates to a promoter that is useful for expressing the nucleotide sequence.
Starch is one of the main storage carbohydrates in plants, especially higher plants. The structure of starch consists of amylose and amylopectin. Amylose consists essentially of straight chains of &agr;-1-4-linked glycosyl residues. Amylopectin comprises chains of &agr;-1-4-linked glycosyl residues with some &agr;-1-6 branches. The branched nature of amylopectin is accomplished by the action of inter alia an enzyme commonly known as the starch branching enzyme (“SBE”). SBE catalyses the formation of branch points in the amylopectin molecule by adding &agr;-1,4 glucans through &agr;-1,6-glucosidic branching linkages. The biosynthesis of amylose and amylopectin is schematically shown in
FIG. 1
, whereas the &agr;-1-4-links and the &agr;-1-6 links are shown in FIG.
2
.
In Potato, it is known that two classes of SBE exist. In our copending international patent applications PCT/EP96/03052 and PCT/EP96/03053, class B potato SBE and a gene encoding it are discussed. In international patent application WO96/34968, class A potato SBE and a cDNA encoding it are disclosed.
It is known that starch is an important raw material. Starch is widely used in the food, paper. and chemical industries. However, a large fraction of the starches used in these industrial applications are post-harvest modified by chemical, physical or enzymatic methods in order to obtain starches with certain required functional properties.
Within the past few years it has become desirable to make genetically modified plants which could be capable of producing modified starches which could be the same as the post-harvest modified starches. It is also known that it may be possible to prepare such genetically modified plants by expression of antisense nucleotide coding sequences. In this regard, June Bourque provides a detailed sunmmary of antisense strategies for the genetic nanipulations in plants (Bourque 1995 Plant Science 105 pp 125-149). At this stage, reference could be made to
FIG. 3
which is a schematic diagram of one of the proposed mechanisms of antisense-RNA inhibition.
In particular, WO 92/11375 reports on a method of genetically modifying potato so as to form amylose-type starch. The method involves the use of an anti-sense construct that can apparently inhibit, to a varying extent, the expression of the gene coding for formation of the branching enzyme in potato. The antisense construct of WO 92/11375 consists of a tuber specific promoter, a transcription start sequence and the first exon of the branching. enzyme in antisense direction. However, WO 92/11375 does not provide any antisense sequence data. In addition, WO 92/11375 only discloses the use of the potato GBSS promoter.
WO 92/14827 reports on a plasmid that, after insertion into the genome of a plant, can apparently cause changes in the carbohydrate concentration and carbohydrate composition. such as the concentration and composition of amylose and amylopectin, in the regenerated plant. The plasmid contains part of the coding sequence of a branching enzyme in an antisense orientation.
EP-A-0647715 reports on the use of antisense endogenous mRNA coding DNA to alter the characteristics and the metabolic pathways of ornamental plants.
EP-A-0467349 reports on the expression of sequences that are antisense to sequences upstream of a promoter to control gene expression.
EP-A-0458367 and U.S. Pat. No. 5,107,065 report on the expression of a nucleotide sequence to regulate gene expression in a plant. The nucleotide sequence is complementary to a mRNA sequence of a gene and may cover all or a portion of the noncoding region of the gene. In other words, the nucleotide sequences of EP-A-0458367 and U.S. Pat. No. 5,107,065 must at least comprise a sequence that is complementary to a coding region. EP-A-0458367 and U.S. Pat. No. 5,107,065 contain minimal sequence information.
WO96/34968 discusses the use of antisense sequences complementary to sequences which encode class A and class B potato SBE to downregulate SBE expression in potato plants. The sequences used are complementary to SBE coding sequences.
Kuipers et al in Mol. Gen. Genet. [1995]246 745-755 report on the expression of a series of nucleotides that are antisense to part of the genomic intron sequences of potato granule bound starch synthetase. Here the antisense intron sequences are attached to a part of the antisense exon sequences—wherein the intron sequences and the exon sequences are naturally associated with each other. In addition, the expressed antisense intron sequences are at most 231 bp in length.
Likewise, Kull et al in J. Genet & Breed. [1995] 49 69-76 report on the expression of a series of nucleotides that are antisense to part of the genomic intron sequences of potato granule bound starch synthetase. Likewise, here the antisense intron sequences are attached to a part of the antisense exon sequences—wherein the intron sequences and the exon sequences are naturally associated with each other. In addition, likewise, the expressed antisense intron sequences are at most 231 bp in length.
Shimada et al in Theor. Appl. Genet. [1993]86 665-672 report on the expression of a series of nucleotides that are antisense to part of the genomic intron sequences of rice granule bound starch synthetase. Here the antisense intron sequences are attached to a part of the antisense exon sequences—wherein the intron sequences and the exon sequences are naturally associated with each other. In addition, the expressed antisense intron sequences are less than 350 bp in length.
Reviews on how enzymatic activity can be affected by expression of particular nucleotide sequences may be found in the teachings of Finnegan and McElroy [1994] Biotechnology 12 883-888; and Matzke and Matzke [1995] TIG 11 1-3.
Whilst it is known that enzymatic activity can be affected by expression of particular nucleotide sequences there is still a need for a method that can more reliably and/or more efficiently and/or more specifically affect enzymatic activity.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a method of affecting enzymatic activity in a plant (or a cell, a tissue or an organ thereof) comprising expressing in the plant (or a cell, a tissue or an organ thereof) a nucleotide sequence wherein the nucleotide sequence partially or completely codes for (is) an intron of the potato class A SBE gene in an antisense orientation optionally together with a nucleotide sequence which codes, partially or completely, for an intron of a class B starch branching enzyme in an antisense or sense orientation; and wherein the nucleotide sequence does not contain a sequence that is antisense to an exon sequence normally associated with the intron.
According to a second aspect of the present invention there is provided a method of affecting enzymatic activity in a starch producing organism (or a cell, a tissue or an organ thereof) comprising expressing in the starch producing organism (or a cell, a tissue or an organ thereof) a nucleotide sequence wherein the nucleotide sequence codes, partially or completely, for an intron of the potato class A SBE gene, in an antisense orientation optionally together with a nucleotide sequence which codes, partially or completely, for an intron of a class B starch branching enzyme in an antisense or sense orientation; and wherein starch branching enzyme activity is affected and/or the levels of amylopectin are affected and/or the composition of starch is changed.
Preferably, the class A SBE gene antisense intron construct
Danisco a/s
Foley & Lardner
Fox David T.
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