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Starch branching enzyme II of potato

Imported: 23 Feb '17 | Published: 22 Oct '02

Bo Ek, Jamshid Khosnoodi, Clas-Tomas Larsson, Håkan Larsson, Lars Rask

USPTO - Utility Patents

Abstract

The present invention relates to an amino acid sequence of second starch branching enzyme (SBE II) of potato and a fragment thereof as well as to the corresponding isolated DNA sequences. Furthermore, the invention relates to vectors comprising such an isolated DNA sequence, to processes for production of transgenic potatoes, and to the use of said potatoes for the production of starch. The starch obtained will show a changed pattern of branching of amylopectin as well as a changed amylose/amylopectin ratio.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows SDS polyacrylamide electrophoresis of proteins extracted from starch of normal potato (lane A) and transgenic potato (lane B). Excised protein bands are marked with arrows. Lane M: Molecular weight marker proteins (kDa).

FIG. 2 shows 4 peptide sequences derived from digested proteins from potato tuber starch.

Claims

1. An isolated DNA sequence encoding starch branching enzyme II (SBE II) of potato, said DNA sequence comprising the nucleotide sequence as shown in SEQ ID No. 1, or variants of said DNA sequence resulting from the degeneracy of the genetic code.

2. Fragments of the isolated DNA sequence as shown in SEQ ID No. 1 and said fragments encoding starch branching enzyme II (SBE II) of potato, which fragments are capable of affecting the amylose/amylopectin ratio in potato starch as well as reducing or changing the pattern of the branching of amylopectin.

3. Fragments according to claim 2 comprising 50-3074 bp of the nucleotide sequence as shown in SEQ ID No. 1, or variants of said fragments resulting from the degeneracy of the genetic code.

4. A fragment according to claim 2, comprising the nucleotide sequence as shown in SEQ ID No. 2.

5. A vector comprising the whole or a functionally active part of the isolated DNA sequence according to claim 1 operably linked to regulatory elements active in potato, said part being of a length sufficient to affect the amylose/amylopectin ratio in potato starch.

6. A vector comprising the whole or a functionally active part of the fragment according to claim 2 operably linked to regulatory elements active in potato, said part being of a length sufficient to affect the amylose/amylopectin ratio in potato starch.

7. A vector comprising the whole or a functionally active part of the fragment according to claim 3 operably linked to regulatory elements active in potato, said part being of a length sufficient to affect the amylose/amylopectin ratio in potato starch.

8. A vector comprising the whole or a functionally active part of the fragment according to claim 4 operably linked to regulatory elements active in potato, said part being of a length sufficient to affect the amylose/amylopectin ratio in potato starch.

9. A process for the production of transgenic potatoes with either an increased or a decreased degree of branching of amylopectin starch, comprising the following steps:

10. A transgenic potato obtainable by the process according to claim 9.

11. A process for isolating starch or starch proteins from the transgenic potato of claim 10, comprising: