Starch Biosynthesis in Higher Plants: The Enzymes of Starch Synthesis

2011 ◽  
pp. 58-76
Author(s):  
I.J. Tetlow ◽  
M.J. Emes
Keyword(s):  
Higher Plants ◽  
Starch Synthesis ◽  
Starch Biosynthesis

scholarly journals Molecular Functions and Pathways of Plastidial Starch Phosphorylase (PHO1) in Starch Metabolism: Current and Future Perspectives

2021 ◽  
Vol 22 (19) ◽  
pp. 10450
Author(s):  
Noman Shoaib ◽  
Lun Liu ◽  
Asif Ali ◽  
Nishbah Mughal ◽  
Guowu Yu ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Molecular Mechanisms ◽  
Higher Plants ◽  
Crop Improvement ◽  
Starch Biosynthesis ◽  
Starch Metabolism ◽  
Protein Protein Interactions ◽  
Starch Phosphorylase ◽  
Integral Role

Starch phosphorylase is a member of the GT35-glycogen-phosphorylase superfamily. Glycogen phosphorylases have been researched in animals thoroughly when compared to plants. Genetic evidence signifies the integral role of plastidial starch phosphorylase (PHO1) in starch biosynthesis in model plants. The counterpart of PHO1 is PHO2, which specifically resides in cytosol and is reported to lack L80 peptide in the middle region of proteins as seen in animal and maltodextrin forms of phosphorylases. The function of this extra peptide varies among species and ranges from the substrate of proteasomes to modulate the degradation of PHO1 in Solanum tuberosum to a non-significant effect on biochemical activity in Oryza sativa and Hordeum vulgare. Various regulatory functions, e.g., phosphorylation, protein–protein interactions, and redox modulation, have been reported to affect the starch phosphorylase functions in higher plants. This review outlines the current findings on the regulation of starch phosphorylase genes and proteins with their possible role in the starch biosynthesis pathway. We highlight the gaps in present studies and elaborate on the molecular mechanisms of phosphorylase in starch metabolism. Moreover, we explore the possible role of PHO1 in crop improvement.

BIOSYNTHESIS AND DEGRADATION OF STARCH IN HIGHER PLANTS

2020 ◽  
Author(s):  
Lungwani Muungo
Keyword(s):  
Higher Plants ◽  
Starch Biosynthesis ◽  
Metabolizing Enzymes ◽  
Transitory Starch ◽  
Leaf Tissues ◽  
Cellular Compartments

Numerous reviews on starch biosynthesis and degradation have appeared inthe 1980s (4, 23, 39, 40, 51, 73, 100, 101, 124, 125). Here we updateestablished concepts and emphasize three topics that we consider to now meritreexamination: the significance of enzyme multiplicity, a comparison ofdegradation of reserve and transitory starch, and the localization of starchdegrading enzymes in starch-free cellular compartments of leaf tissues. Westress the cell physiological aspects of starch metabolizing enzymes.

scholarly journals Pyrophosphate:fructose 6-phosphate 1-phosphotransferase and glycolysis in non-photosynthetic tissues of higher plants

1985 ◽  
Vol 227 (1) ◽  
pp. 299-304 ◽  
Author(s):  
T ap Rees ◽  
J H Green ◽  
P M Wilson
Keyword(s):  
Pisum Sativum ◽  
Beta Vulgaris ◽  
Higher Plants ◽  
Starch Synthesis ◽  
Carbohydrate Oxidation ◽  
Allium Porrum ◽  
Catalytic Activities ◽  
Net Flux ◽  
Arum Maculatum ◽  
Fructose 1,6 Bisphosphate

The activity of pyrophosphate:fructose-6-phosphate 1-phosphotransferase [PFK (PPi); EC 2.7.1.90] in extracts of the storage tissues of leek (Allium porrum), beetroot (Beta vulgaris) and roots of darnel (Lolium temulentum) exceeded 0.15 mumol/min per g fresh wt. As net flux from fructose 1,6-bisphosphate to fructose 6-phosphate in these tissues is unlikely, it is suggested that PFK (PPi) does not contribute to gluconeogenesis or starch synthesis. The maximum catalytic activities of PFK (PPi) in apex, stele and cortex of the root of pea (Pisum sativum) and in the developing and the thermogenic club of the spadix of cuckoo-pint (Arum maculatum) were measured and compared with those of phosphofructokinase, and to estimates of the rates of carbohydrate oxidation. PPi and fructose 2,6-bisphosphate in Arum clubs were measured. The above measurements are consistent with a glycolytic role for PFK (PPi) in tissues where there is marked biosynthesis, but not in the thermogenic club of Arum. The possibility that PFK (PPi) is a means of synthesizing pyrophosphate is discussed.

scholarly journals Starch biosynthesis in developing seeds

2010 ◽  
Vol 21 (1) ◽  
pp. 5-32 ◽  
Author(s):  
Ian J. Tetlow
Keyword(s):  
Seedling Establishment ◽  
Biological Function ◽  
Starch Synthesis ◽  
Industrial Applications ◽  
Starch Biosynthesis ◽  
Post Translational Modification ◽  
Developing Seeds ◽  
Starch Structure ◽  
Wide Range ◽  
Storage Starch

AbstractStarch is globally important as a source of food and, in addition, has a wide range of industrial applications. Much of this agriculturally produced starch is synthesized in developing seeds, where its biological function is to provide energy for seedling establishment. Storage starch in developing seeds is synthesized in heterotrophic plastids called amyloplasts and is distinct from the transient synthesis of starch in chloroplasts. This article reviews our current understanding of storage starch biosynthesis occurring in these organelles and discusses recent advances in research in this field. The review discusses starch structure and granule initiation, emerging ideas on the evolution of the pathway, the enzymes of starch synthesis, and the post-translational modification and regulation of key enzymes of amylopectin biosynthesis.

scholarly journals NnABI4-Mediated ABA Regulation of Starch Biosynthesis in Lotus (Nelumbo nucifera Gaertn)

2021 ◽  
Vol 22 (24) ◽  
pp. 13506
Author(s):  
Peng Wu ◽  
Ailian Liu ◽  
Yongyan Zhang ◽  
Kai Feng ◽  
Shuping Zhao ◽  
...  
Keyword(s):  
Theoretical Basis ◽  
Plant Hormone ◽  
Nuclear Protein ◽  
Starch Content ◽  
Starch Synthesis ◽  
Starch Biosynthesis ◽  
Luciferase Assay ◽  
Starch Accumulation ◽  
Exogenous Aba ◽  
Total Starch

Starch is an important component in lotus. ABA is an important plant hormone, which plays a very crucial role in regulating plant starch synthesis. Using ‘MRH’ as experimental materials, the leaves were sprayed with exogenous ABA before the rhizome expansion. The results showed that stomatal conductance and transpiration rate decreased while net photosynthetic rate increased. The total starch content of the underground rhizome of lotus increased significantly. Meanwhile, qPCR results showed that the relative expression levels of NnSS1, NnSBE1 and NnABI4 were all upregulated after ABA treatment. Then, yeast one-hybrid and dual luciferase assay suggested that NnABI4 protein can promote the expression of NnSS1 by directly binding to its promoter. In addition, subcellular localization results showed that NnABI4 encodes a nuclear protein, and NnSS1 protein was located in the chloroplast. Finally, these results indicate that ABA induced the upregulated expression of NnABI4, and NnABI4 promoted the expression of NnSS1 and thus enhanced starch accumulation in lotus rhizomes. This will provide a theoretical basis for studying the molecular mechanism of ABA regulating starch synthesis in plant.

Plant ADP-Glucose Pyrophosphorylase -Recent Advances and Biotechnological Perspectives (A Review)

1991 ◽  
Vol 46 (7-8) ◽  
pp. 605-612 ◽  
Author(s):  
Leszek A. Kleczkowski ◽  
Per Villand ◽  
Anders Lönneborg ◽  
Odd-Arne Olsen ◽  
Ernst Lüthi
Keyword(s):  
Carbohydrate Metabolism ◽  
Starch Synthesis ◽  
Starch Biosynthesis ◽  
Future Research ◽  
Developmentally Regulated ◽  
Recent Advances ◽  
Regulated Expression ◽  
Key Enzyme ◽  
Adp Glucose Pyrophosphorylase ◽  
Complex Target

Abstract Recent advances in studies on plant ADP -glucose pyrophosphorylase (AGP), the key enzyme of starch biosynthesis, are presented. AGP constitutesthe First committed and highly regulated step of starch synthesis in all plan ttissues. The importance of AGP in carbohydrate metabolism and several of its features, such as potent regulation by cellular effectors (3-phosphoglycerate and Pi), an unusual two subunit-types structure, tissue-specific and developmentally-regulated expression, and presence of the AGP -deficient mutants, make it an attractive, but complex, target forbiotechnological manipulations. Some strategies for future research on AGP are discussed.

STARCH SYNTHESIS IN CHLORELLA VULGARIS

1954 ◽  
Vol 32 (1) ◽  
pp. 452-464 ◽  
Author(s):  
J. M. Bailey ◽  
A. C. Neish
Keyword(s):  
Cell Wall ◽  
Calcium Chloride ◽  
Chlorella Vulgaris ◽  
Higher Plants ◽  
Starch Synthesis ◽  
Dry Weight ◽  
Cell Wall Polysaccharide ◽  
Branching Enzyme

Chlorella vulgaris was found to deposit starch, in amounts up to 20% of the dry weight of the cells, when grown in a medium containing glucose. The cells did not contain cellulose or chitin. The starch was difficult to extract, being associated with an alkali-soluble, dextrorotatory, cell-wall polysaccharide. The starch, after extraction by a 26% solution of calcium chloride at 120 °C., had properties quite similar to starches from higher plants. It was composed of amylose (30–40%) and amylopectin. Glucose-1-C14 was incorporated into the starch, by growing cells, without much breakdown and resynthesis. Cell-free extracts, obtained from the alga, contained a phosphorylase and a branching enzyme similar to those of the potato. These brought about the synthesis of an amylopectin–glycogen type polysaccharide from glucose-1-phosphate. It is concluded that the mechanism of starch synthesis in Chlorella vulgaris is essentially the same as in higher plants.

Starch synthesis in potato tubers transformed with the wheat genes for ADPglucose pyrophosphorylase

2002 ◽  
Vol 29 (8) ◽  
pp. 975 ◽  
Author(s):  
Kathryn A. Vardy ◽  
Michael J. Emes ◽  
Michael M. Burrell
Keyword(s):  
Solanum Tuberosum L ◽  
Starch Content ◽  
Starch Synthesis ◽  
Small Subunit ◽  
Starch Biosynthesis ◽  
Potato Tubers ◽  
Potato Plants ◽  
Adpglucose Pyrophosphorylase ◽  
Plastid Targeting

The aim of this work was to study the role of ADPglucose pyrophosphorylase (AGPase) in starch biosynthesis of non-photosynthetic organs. Agrobacterium tumefaciens was used to transform potato plants (Solanum tuberosum L. cv. Desire�) with the wheat AGPase genes (AGP-S and AGP-L, coding for the small and large subunits, respectively). Neither of these genes contains a recognisable plastid targeting sequence. Southern analysis and analysis of starch content identified four lines that contained both wheat sequences. Immunoblotting indicated that, in the tubers, three lines expressed the wheat small subunit (AGP-S), but AGP-L cross-reacting protein was not apparent. The fourth transgenic line had reduced AGPase activity. AGPase activity in the AGP-transgenic tubers ranged from 15 to 165% of that found in β-glucuronidase (GUS) control lines.

scholarly journals PDIL1-2 can indirectly and negatively regulate expression of the AGPL1 gene in bread wheat

2019 ◽  
Vol 52 (1) ◽  
Author(s):  
Jie Dong ◽  
Yongxing Zheng ◽  
Yihan Fu ◽  
Jinxi Wang ◽  
Shasha Yuan ◽  
...  
Keyword(s):  
Higher Plants ◽  
Large Subunit ◽  
Functional Characterization ◽  
Starch Biosynthesis ◽  
Kernel Weight ◽  
Starch Accumulation ◽  
Virus Induced Gene Silencing ◽  
Gene Encoding ◽  
Key Enzyme ◽  
And Function

Abstract Background ADP-glucose pyrophosphorylase (AGPase), the key enzyme in plant starch biosynthesis, is a heterotetramer composed of two identical large subunits and two identical small subunits. AGPase has plastidial and cytosolic isoforms in higher plants, whereas it is mainly detected in the cytosol of grain endosperms in cereal crops. Our previous results have shown that the expression of the TaAGPL1 gene, encoding the cytosolic large subunit of wheat AGPase, temporally coincides with the rate of starch accumulation and that its overexpression dramatically increases wheat AGPase activity and the rate of starch accumulation, suggesting an important role. Methods In this study, we performed yeast one-hybrid screening using the promoter of the TaAGPL1 gene as bait and a wheat grain cDNA library as prey to screen out the upstream regulators of TaAGPL1 gene. And the barley stripe mosaic virus-induced gene-silencing (BSMV-VIGS) method was used to verify the functional characterization of the identified regulators in starch biosynthesis. Results Disulfide isomerase 1-2 protein (TaPDIL1-2) was screened out, and its binding to the TaAGPL1-1D promoter was further verified using another yeast one-hybrid screen. Transiently silenced wheat plants of the TaPDIL1-2 gene were obtained by using BSMV-VIGS method under field conditions. In grains of BSMV-VIGS-TaPDIL1-2-silenced wheat plants, the TaAGPL1 gene transcription levels, grain starch contents, and 1000-kernel weight also significantly increased. Conclusions As important chaperones involved in oxidative protein folding, PDIL proteins have been reported to form hetero-dimers with some transcription factors, and thus, our results suggested that TaPDIL1-2 protein could indirectly and negatively regulate the expression of the TaAGPL1 gene and function in starch biosynthesis.

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