Chemistry: molecular biology and microbiology – Enzyme – proenzyme; compositions thereof; process for... – Hydrolase
Patent
1996-04-18
1999-12-14
Achutamurthy, Ponnathapura
Chemistry: molecular biology and microbiology
Enzyme , proenzyme; compositions thereof; process for...
Hydrolase
435 76, 435 691, 435200, 4352523, 4353201, 536 232, 536 236, 800205, C12N 944, C12N 120, C12N 1500, C07H 2104
Patent
active
060016280
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to DNA sequences which on the codogenic strand, code plant debranching enzymes whose transcripts formed in transgenic plants code new proteins with the enzymatic activity of debranching enzymes which in transgenic plants reduce the degree of branching of amylopectin starch. (The invention also Relates) to DNA sequences which on the codogenic strand code plant debranching enzymes whose transcripts formed in transgenic plants prevent the synthesis of proteins with the enzymatic activity of debranching enzymes, which in transgenic plants increases the degree of branching of amylopectin starch, and also to recombinant plasmids on which these DNA sequences are localized and which can be introduced into plant cells and plants.
The invention also relates to a process for the production of plants changed by genetic engineering whose amylopectin starch is modified, and to the modified starch obtainable from these plants.
Polysaccharides such as starch are, alongside along with oils, fats and proteins, essential renewable raw materials from plants.
A decisive factor which stands in the way of the use of renewable raw materials is the lack of substances which precisely meet the requirements of the chemical industry in regard to form, structure, or other physico-chemical parameters. In order to make the application of renewable raw materials feasible in as many fields of use as possible, it is particularly important to achieve a great material diversity. In regard to polysaccharides, this means that, for example, as many different forms of starch must be provided as possible. This necessitates considering both strongly branched forms which are characterized by a high surface reactivity in their chemical properties, and mildly branched types which are distinguished by a high uniformity of structure. Uniformity of structure is an important prerequisite for highly efficient reaction control during chemical syntheses.
Although starch is a polymer comprising chemically uniform basic components, the glucose molecules, it is a complex mixture of very different molecule forms which differ in respect to their degree of polymerization and the occurrence of branchings of the glucose chains. Starch is therefore not a uniform raw material. In particular, a distinction is drawn between amylose starch, an essentially unbranched polymer comprising .alpha.-1,4 glycosidically linked glucose molecules, and amylopectin starch, which for its part is a complex mixture of differently branched glucose chains. The branchings come about through the occurrence of additional .alpha.-1,6 glycosidic linkages.
In typical plants for starch production, such, for example maize or potato, the two forms of starch occur in a ratio of roughly 25 parts amylose to 75 parts amylopectin.
In regard to the uniformity of a basic substance, such as starch, for its application in the industrial sector, plants are needed which, for example, contain only the component amylopectin or plants which contain only the component amylose. In regard to the versatility of the raw material starch, plants are needed which show forms of amylopectin with differently marked branching. There is thus a great interest in enzymes of the starch metabolism which can modify the degree of branching of the starch molecules, or in gene sequences which can be used for the genetically changing plants so as to be able to synthesize different forms of starch in plants.
It is already known that for certain plant species, for example maize, plant types which contain only amylopectin can be produced by mutagenesis in which individual genes of the plant are inactivated. For potato, a genotype which forms no amylose was likewise produced by chemical mutagenesis with a haploid line (Hovenkamp-Hermelink et al., 1987, Theor Appl Genet 75: 217-221). Haploid lines, or the homozygotic diploid or tetraploid lines developed from them, are not usable in agriculture, however. The mutagenesis technique is not applicable to the agriculturally interestin
REFERENCES:
patent: 4454161 (1984-06-01), Okada
patent: 4886678 (1989-12-01), Chiu
Suggs et al. PNAS 78(11), 6613-17, 1981.
Plant Physiology vol. 100, 1992, pp. 1083-1086 Shewmaker, C.K., et al. `Modifying starch biosynthesis with transgenes in potatoes` see p. 1085, left column, last paragraph.
Agric Biol. Chem., vol. 47, No. 4, 1983, pp. 771-779 Ishizaki, Y., et al. `Debranching enzymes of potato tubers (Solanum tuberosum L.). I. Purification and some properties of potato isoamylase` cited in the application, see the whole document.
Chemical Abstracts, vol. 99, No. 9, 1983, Columbus, Ohio, US: abstract No. 66467 Ishizaki, Y., et al. Debranching enzymes of potato tubers (solanum tuberosum L.).
II. Purification of a pullulanase (R-enzyme) from potato tubers and comparison of its properties with those of the potato isoamylase see abstract & Denpun Kagaku, vol. 30, No. 1, 1983, pp. 19-29.
J. Bacteriology, vol. 169, No. 5, May 1987 pp. 2301-2306 Katsuragi, N., et al. `Entire nucleotide sequence of pullulanase gene of Klebsiella aerogenes W70` see figure 2.
Emmermann Michael
Kossmann Jens
Virgin Ivar
Achutamurthy Ponnathapura
Hoechst Schering AgrEvo GmbH
Saidha Tekchand
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