Unlike EC 2.4.1.11, glycogen(starch) synthase and EC 2.4.1.21, starch synthase, which use UDP-glucose and ADP-glucose, respectively, this enzyme can use either UDP- or ADP-glucose. Mutants that lack the Wx (waxy) allele cannot produce this enzyme, which plays an important role in the normal synthesis of amylose. In such mutants, only amylopectin is produced in the endosperm or pollen .
Unlike EC 2.4.1.11, glycogen(starch) synthase and EC 2.4.1.21, starch synthase, which use UDP-glucose and ADP-glucose, respectively, this enzyme can use either UDP- or ADP-glucose. Mutants that lack the Wx (waxy) allele cannot produce this enzyme, which plays an important role in the normal synthesis of amylose. In such mutants, only amylopectin is produced in the endosperm [3] or pollen [5].
GBSS1 can form oligomers in rice endosperm, and oligomerized OsGBSS1 exhibits much higher specific enzymatic activity than the monomer. A monomer-oligomer transition equilibrium occurs in the endosperm during development. Redox potential is a key factor affecting the oligomer percentage as well as the enzymatic activity. Adenosine diphosphate glucose, the direct donor of glucose, also impacts GBSS1 oligomerization in a concentration-dependent manner. GBSS1 oligomerization is influenced by phosphorylation status, which is strongly enhanced by mitogen-activated protein kinase MAPK and ATP treatment and is sharply weakened by protein phosphatase treatment
the very low and low apparent amylose content levels are tightly associated with a G to T in the first intron whereas intermediate and high amylose is associated with a T genotype at SNP in exon 10. The correlation between the combination of T genotype at SNP in the first intron, C in exon 6, or C in exon 10 is predominant among low amylose rice varieties, existence of Wxop allele in Vietnamese rice germplasm. The low amylose properties of Vietnamese local rice germplasm are attributable to spontaneous mutations at exons, and not at the splicing donor site
the very low and low apparent amylose content levels are tightly associated with a G to T in the first intron whereas intermediate and high amylose is associated with a T genotype at SNP in exon 10. The correlation between the combination of T genotype at SNP in the first intron, C in exon 6, or C in exon 10 is predominant among low amylose rice varieties, existence of Wxop allele in Vietnamese rice germplasm. The low amylose properties of Vietnamese local rice germplasm are attributable to spontaneous mutations at exons, and not at the splicing donor site
differences in the debranched starch molecular size distribution between Ilpumbyeo and Goami 2 are similar between Nipponbare and ami-BEIIb, a transgenic line with downregulated SBEIIb
differences in the debranched starch molecular size distribution between indica variety IR36 and its SBEIIb mutant, IR36ae, which has more amylose chains than IR36 due to more active GBSSI
phosphorylation status is strongly enhanced by mitogen-activated protein kinase MAPK and ATP treatment and is sharply weakened by protein phosphatase treatment
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
recombinant His-tagged GBSSI catalytic domain, residues Met83-Pro609, free or in complex with ADP-glucose, sitting drop vapour diffusion method, mixing of 0.0003 ml of 6 mg/ml protein in 20 mM Tris, pH 8.0, and 0.2 M NaCl, with 0.0003 m of reservoir solution, containing 1.5 M lithium sulfate and 0.1 M HEPES-sodium, pH 7.5, and equilibration against 0.05 ml of reservoir solution, 20°C, 4 weeks, X-ray diffraction structure determination and analysis at 2.7-3.0 A resolution
the mutation has no detectable effect on GBSSI activity in vitro, however, it notably reduces the binding of GBSSI to starch granules, resulting in a reduction of amylose content in rice seeds
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PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
recombinant His-tagged GBSSI catalytic domain, residues Met83-Pro609, from Escherichia coli strain BL21 by nickel affinity chromatography and gel filtration
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
granule-bound starch synthase I gene or Waxy gene, alleles can be classified into seven groups that reflect differences in apparent amylose content, DNA and amino acid sequence determination and analysis, expression analysis
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
analysis of 352 Vietnamese rice cultivars reveals a wide range of variation in apparent amylose content and the expression level of granule-bound starch synthase I. Alleles can be classified into seven groups that reflect differences in apparent amylose content. The very low and low apparent amylose content levels are tightly associated with a G to T in the first intron whereas intermediate and high amylose is associated with a T genotype at a single-nucleotide polymorphism in exon 10. The correlation between the combination of T genotype at single-nucleotide polymorphism in the first intron, C in exon 6, or C in exon 10 is predominant among low amylose rice varieties. The low amylose properties of Vietnamese local rice germplasm are attributable to spontaneous mutations at exons, and not at the splicing donor site
maximal expression of granule-bound starch synthase occurs in mid-stage of endosperm development, GBSS activity of Wanjing 9522 grains increases after anthesis and reaches ist maximal activity at day 18 and keeps this high level for about 6 days, and then decreases steadily
the starch associated SSIIa protein content is positively correlated with gelatinization temperature and level of amylopectin chains with degree of polymerization 12-24
analysis of 352 Vietnamese rice cultivars reveals a wide range of variation in apparent amylose content and the expression level of granule-bound starch synthase I. Alleles can be classified into seven groups that reflect differences in apparent amylose content. The very low and low apparent amylose content levels are tightly associated with a G to T in the first intron whereas intermediate and high amylose is associated with a T genotype at a single-nucleotide polymorphism in exon 10. The correlation between the combination of T genotype at single-nucleotide polymorphism in the first intron, C in exon 6, or C in exon 10 is predominant among low amylose rice varieties. The low amylose properties of Vietnamese local rice germplasm are attributable to spontaneous mutations at exons, and not at the splicing donor site
serum from patients allergic to maize shows IgE binding to a 56 kDa protein present in both maize and rice, that is abundant in the rice endosperm. The protein is identical with granule-bound starch synthase, a product of the Waxy gene. In a Waxy mutant of rice, the IgE-binding protein is absent. Waxy mutants of rice may be a potential source of hypoallergenic diet for patients sensitized to the 56 kDa rice allergen
Effects of the activities of key enzymes involved in starch biosynthesis on the fine structure of amylopectin in developing rice (Oryza sativa L.) endosperms