Nucleic acid molecules encoding starch phosphorylase from maize

Details Nucleic acid molecules encoding starch phosphorylase from maize Nucleic acid molecules encoding starch phosphorylase from maize

1999-09-10

2002-03-05

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, C800S285000, C800S320000, C800S320100, C800S320200, C800S320300, C800S317200, C536S023600, C435S069100, C435S101000, C435S194000, C435S320100, C435S412000, C435S419000, C435S468000

Reexamination Certificate

active

06353154

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to nucleic acid molecules encoding a starch phosphorylase from maize. Furthermore, the present invention relates to vectors, bacteria as well as to plant cells transformed with the described nucleic acid molecules and to the plants containing the same. Moreover, methods for the production of transgenic plants are described which, due to the introduction of DNA molecules encoding a starch phosphorylase from maize, synthesize a starch which is modified in its properties.
With respect to the increasing significance which has recently been ascribed to vegetal substances as regenerative sources of raw materials, one of the objects of biotechnological research is to try to adapt vegetal raw materials to the demands of the processing industry. In order to enable the use of regenerative raw materials in as many areas as possible, it is furthermore important to obtain a large variety of substances. Apart from oils, fats and proteins, polysaccharides constitute the essential regenerative raw materials derived from plants. Apart from cellulose, starch maintains an important position among the polysaccharides, being one of the most significant storage substances in higher plants. Among those, maize is one of the most interesting plants as it is the most important cultivated plant for the production of starch.
The polysaccharide starch is a polymer made up of chemically homogeneous basic components, namely the glucose molecules. However, it constitutes a highly complex mixture from various types of molecules which differ from each other in their degree of polymerization and in the degree of branching of the glucose chains. Therefore, starch is not a homogeneous raw material. One differentiates particularly between amylose-starch, a basically non-branched polymer made up of &agr;-1,4-glycosidically branched glucose molecules, and amylopectin-starch which in turn is a complex mixture of various branched glucose chains. The branching results from additional &agr;-1,6-glycosidic interlinkings. In plants used typically for the production of starch, such as maize or potato, the synthesized starch consists of approximately 25% amylose-starch and of about 75% amylopectin-starch.
In order to enable as wide a use of starch as possible, it seems to be desirable that plants be provided which are capable of synthesizing modified starch which is particularly suitable for various uses. One possibility to provide such plants—apart from breeding methods—is the specific genetic modification of the starch metabolism of starch-producing plants by means of recombinant DNA techniques. However, a prerequisite therefore is to identify and to characterize the enzymes involved in the starch synthesis and/or the starch modification as well as to isolate the respective DNA molecules encoding these enzymes.
The biochemical pathways which lead to the production of starch are basically known. The starch synthesis in plant cells takes place in the plastids. In photosynthetically active tissues these are the chloroplasts, in photosynthetically inactive, starch-storing tissues the amyloplasts.
The most important enzymes involved in starch synthesis are starch synthases as well as branching enzymes. In the case of other enzymes and also, for example, in the case of starch phosphorylases, their precise role during starch biosynthesis is unknown.
In order to provide further possibilities in order to modify starch-storing plants in such a way that they synthesize a modified starch, it is necessary to identify DNA sequences encoding further enzymes involved in the starch biosynthesis, such as starch phosphorylase. Such proteins are known, for example, from Vicia faber (Buchner et al., Planta 199 (1996), 64-73), Solanum tuberosum (St. Pierre and Brisson, Plant Science 110 (1995), 193-203; Sonnewald et al., Plant. Mol. Biol. 27 (1995), 567-576; Bhatt and Knowler, J. Exp. Botany 41 (Suppl.) (1990), 5-7; Camirand et al., Plant Physiol. 89 (4 Suppl.) (1989), 61), Ipomoea batatas (Lin et al., Plant Physiol. 95 (1991), 1250-1253), sugar beet (Li et al., Ohio J. of Sci. 90 (1990), 8), spinache and maize (Mateyka and Schnarrenberger, Plant Physiol. 86 (1988), 417-422) as well as pea (Conrads et al., Biochim. Biophys. Acta 882 (1986), 452-464).
They are characterized as enzymes catalyzing the reversible phosphorylysis of terminal glucose units of &agr;-1,4-glucans according to the following equation:
glucan
n
+P
i
|⇄glucose-1-phosphate+glucan
n−1
Depending on the relative concentration of P
i
and glucose-1-phosphate (G1P), the enzyme may have a degrading or, as the case may be, synthesizing effect on the glucans (Waldmann et al., Carbohydrate Research 157 (1986), C4-C7). On the basis of the differences in the localization, in the affinities to the glucans and in the regulation and the size of monomers, the plant starch phosphorylases are classified as follows:
Type 1: situated within the cytosol of plant cells; very high affinity to longer-chained branched glucans; unregulated; monomeric size of approximately 90 kD;
Type 2: situated within the plastids of plant cells; affinity to maltodextrines; low affinity to polyglucans; unregulated; monomeric size of approximately 105 kD.
DNA sequences encoding the corresponding starch phosphorylases have sofar been isolated only from a small number of plant species such as potato (Buchner et al., loc. cit.; Sonnewald et al., loc. cit.; Bhatt and Knowler, loc. cit.; Camirand et al., loc. cit.), sweet potato (Lin et al., loc. cit., Lin et al., Plant Physiol. 95 (1991), 1250-1253) and rice (database accession number DDBJ No. D23280). Up to now, such sequences are not known from maize.
Therefore, it is the object of the present invention to provide further nucleic acid molecules encoding enzymes involved in starch biosynthesis and by means of which genetically modified plants may be produced that show an elevated or reduced activity of those enzymes, thereby prompting a modification in the chemical and/or physical properties of the starch synthesized in these plants.
This object is achieved by the provision of the embodiments described in the claims.
SUMMARY OF THE INVENTION
Therefore, the present invention relates to nucleic acid molecules encoding proteins with the biological activity of a starch phosphorylase from maize, wherein such molecules preferably encode proteins which comprise the amino acid sequence depicted under Seq ID No. 2. The invention particularly relates to nucleic acid molecules which comprise all or part of the nucleotide sequence mentioned under Seq ID No. 1, preferably molecules, which comprise the coding region indicated in Seq ID No. 1 or, as the case may be, corresponding ribonucleotide sequences.
The present invention further relates to nucleic acid molecules which encode a starch phosphorylase from maize and one strand of which hybridizes to one of the above-mentioned molecules. Nucleic acid molecules that encode a starch phosphorylase from maize and the sequence of which differs from the nucleotide sequences of the above-mentioned molecules due to the degeneracy of the genetic code are also the subject-matter of the invention.
The invention also relates to nucleic acid molecules showing a sequence which is complementary to the whole or to a part of one of the above-mentioned sequences.
In this invention the term “hybridization” signifies hybridization under conventional hybridizing conditions, preferably under stringent conditions as described for example in Sambrook et al., Molecular Cloning, A Laboratory Manual, 2nd Edition (1989) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.). “Hybridization” preferably means that a hybridization takes place under the following conditions:
Hybridization buffer: 2×SSC; 10×Denhardt's solution (Fikoll 400+PEG+BSA; ratio 1:1:1); 0.1% SDS; 5 mM EDTA; 50 mM Na
2
HPO
4
; 250 &mgr;g/ml herring sperm DNA; 50 &mgr;g/ml tRNA; or 0.25 M sodium phosphate buffer pH 7.2; 1 mM EDTA; 7% SDS
Hybridization temperature T=65 to 68° C

Affiliated with

Also associated with

Rating

Nucleic acid molecules encoding starch phosphorylase from maize does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Nucleic acid molecules encoding starch phosphorylase from maize, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nucleic acid molecules encoding starch phosphorylase from maize will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2880033