Three isoforms of starch synthase and two isoforms of branching enzyme are present in potato tuber starch

Larsson, Clas-Tomas; Hofvander, Per; Khoshnoodi, Jamshid; Ek, Bo; Rask, Lars; Larsson, Håkan

doi:10.1016/0168-9452(96)04408-1

Cited by 58 publications

(35 citation statements)

References 25 publications

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“…The consequence of this reaction is to increase the number of nonreducing ends within the molecule, thus facilitating the elongation by the starch synthases. Two to three genetically independent isoforms of SBEs were observed in most plants (Fisher et al, 1996a;Larsson et al, 1996Larsson et al, , 1998Morell et al, 1997;Mizuno et al, 1992;Nakamura et al, 1992). Depending on their peptide sequence, these SBEs were categorized into two classes named SBEI (or B family) and SBEII (or A family).…”

Section: Introductionmentioning

confidence: 99%

Mutants of Arabidopsis Lacking Starch Branching Enzyme II Substitute Plastidial Starch Synthesis by Cytoplasmic Maltose Accumulation

et al. 2006

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Three genes, BE1, BE2, and BE3, which potentially encode isoforms of starch branching enzymes, have been found in the genome of Arabidopsis thaliana. Although no impact on starch structure was observed in null be1 mutants, modifications in amylopectin structure analogous to those of other branching enzyme II mutants were detected in be2 and be3. No impact on starch content was found in any of the single mutant lines. Moreover, three double mutant combinations were produced (be1 be2, be1 be3, and be2 be3), and the impact of the mutations on starch content and structure was analyzed. Our results suggest that BE1 has no apparent function for the synthesis of starch in the leaves, as both be1 be2 and be1 be3 double mutants display the same phenotype as be2 and be3 separately. However, starch synthesis was abolished in be2 be3, while high levels of a-maltose were assayed in the cytosol. This result indicates that the functions of both BE2 and BE3, which belong to class II starch branching enzymes, are largely redundant in Arabidopsis. Moreover, we demonstrate that maltose accumulation depends on the presence of an active ADP-glucose pyrophosphorylase and that the cytosolic transglucosidase DISPROPORTIONATING ENZYME2, required for maltose metabolization, is specific for b-maltose.

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Section: Introductionmentioning

confidence: 99%

Mutants of Arabidopsis Lacking Starch Branching Enzyme II Substitute Plastidial Starch Synthesis by Cytoplasmic Maltose Accumulation

et al. 2006

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“…BE is the only enzyme that can introduce ␣-1,6-glucosidic linkages into ␣-polyglucans and, therefore, it plays an essential role in the biosynthesis of amylopectin. The BEs from various higher plants appear to be composed of two types, namely BEI and BEII from maize (Zea mays; Boyer and Preiss, 1978a;Fisher and Boyer, 1983;Guan and Preiss, 1993;Guan et al, 1997), wheat (Triticum aestivum; Morell et al, 1997), and barley (Hordeum vulgare; Sun et al, 1997), and the A-type and B-type from pea (Pisum sativum; Burton et al, 1995;Martin and Smith, 1995) and potato (Solanum tuberosum; Larsson et al, 1996Larsson et al, , 1998. At least three isoforms of BE have been identified in rice (Oryza sativa) endosperm (Mizuno et al, 1992;Nakamura et al, 1992).…”

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confidence: 99%

Biochemical and Genetic Analysis of the Effects ofAmylose-Extender Mutation in Rice Endosperm

et al. 2001

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Biochemical analysis of amylose-extender (ae) mutant of rice (Oryza sativa) revealed that the mutation in the gene for starch-branching enzyme IIb (BEIIb) specifically altered the structure of amylopectin in the endosperm by reducing short chains with degree of polymerization of 17 or less, with the greatest decrease in chains with degree of polymerization of 8 to 12. The extent of such change was correlated with the gelatinization properties of the starch granules, as determined in terms of solubility in urea solution. The ae mutation caused a dramatic reduction in the activity of BEIIb. The activity of soluble starch synthase I (SSI) in the ae mutant was significantly lower than in the wild type, suggesting that the mutation had a pleiotropic effect on the SSI activity. In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation. Therefore, it is stressed that the function of BEIIb cannot be complemented by BEIIa and BEI. These results strongly suggest that BEIIb plays a specific role in the transfer of short chains, which might then be extended by SS to form the A and B 1 chains of amylopectin cluster in rice endosperm.Starch is composed of two types of molecule, namely amylose and amylopectin. Amylose is an essentially linear molecule composed of ␣(134)-linked glucosidic chains, whereas amylopectin is a highly branched glucan with ␣(136) glucosidic bonds that connect linear chains. The ␣-1,4 chains of amylopectin consist of A chains that carry no additional chains, B chains that carry A chains or other B chains, and a C chain that includes the reducing terminus (Peat et al., 1952). Hizukuri (1986) proposed a cluster model for amylopectin. In this model, A and B 1 chains form a single cluster, whereas B 2 and B 3 chains extend to two and three clusters, respectively. Hanashiro et al. (1996) proposed that, in amylopectin, chains of degree of polymerization (DP) Ϲ12, 13 Ϲ DP Ϲ 24, 25 Ϲ DP Ϲ 36, and DP м 37 correspond to A chains, B 1 chains, B 2 chains, and B 3 and longer chains, respectively.

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“…They are referred to as BEI and BEII in maize (Zea mays; Boyer and Preiss, 1978;Fisher and Boyer, 1983;Guan and Preiss, 1993;Guan et al, 1997), rice (Oryza sativa; Nakamura et al, 1992;Mizuno et al, 1993), wheat (Triticum aestivum; Morell et al, 1997), and barley (Hordeum vulgare; Sun et al, 1997), and as B-type and A-type in pea (Pisum sativum; Burton et al, 1995;Martin and Smith, 1995), kidney bean (Phaseolus vulgaris; Hamada et al, 2001), and potato (Solanum tuberosum; Larsson et al, 1996Larsson et al, , 1998. They can be distinguished from each other based on their distinct biochemical and physico-chemical properties, e.g.…”

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confidence: 99%

Starch-Branching Enzyme I-Deficient Mutation Specifically Affects the Structure and Properties of Starch in Rice Endosperm

Satoh

Nishi²,

Yamashita³

et al. 2003

Plant Physiology

258

202

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We have isolated a starch mutant that was deficient in starch-branching enzyme I (BEI) from the endosperm mutant stocks of rice (Oryza sativa) induced by the treatment of fertilized egg cells with N-methyl-N-nitrosourea. The deficiency of BEI in this mutant was controlled by a single recessive gene, tentatively designated as starch-branching enzyme mutant 1 (sbe1). The mutant endosperm exhibited the normal phenotype and contained the same amount of starch as the wild type. However, the mutation apparently altered the fine structure of amylopectin. The mutant amylopectin was characterized by significant decrease in both long chains with degree of polymerization (DP) Ն 37 and short chains with DP 12 to 21, marked increase in short chains with DP Յ 10 (A chains), and slight increase in intermediate chains with DP 24 to 34, suggesting that BEI specifically synthesizes B 1 and B 2-3 chains. The endosperm starch from the sbe1 mutant had a lower onset concentration for urea gelatinization and a lower onset temperature for thermo-gelatinization compared with the wild type, indicating that the genetic modification of amylopectin fine structure is responsible for changes in physicochemical properties of sbe1 starch.

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Three isoforms of starch synthase and two isoforms of branching enzyme are present in potato tuber starch

Cited by 58 publications

References 25 publications

Mutants of Arabidopsis Lacking Starch Branching Enzyme II Substitute Plastidial Starch Synthesis by Cytoplasmic Maltose Accumulation

Mutants of Arabidopsis Lacking Starch Branching Enzyme II Substitute Plastidial Starch Synthesis by Cytoplasmic Maltose Accumulation

Biochemical and Genetic Analysis of the Effects ofAmylose-Extender Mutation in Rice Endosperm

Starch-Branching Enzyme I-Deficient Mutation Specifically Affects the Structure and Properties of Starch in Rice Endosperm

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