Starch biosynthesis and its regulation

Preiss, Jack; Ball, Kathryn L.; Smith-White, Brian; Iglesias, Alberto A.; Kakefuda, Genichi; Li, L.

doi:10.1042/bst0190539

Cited by 94 publications

(49 citation statements)

References 3 publications

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“…2) were labeled in the spinach leaf LS (8, 9). The multiple labeling patterns of the LS suggest that this subunit type plays a more dominant role in allosteric regulation than the small subunit, a view supported by genetic studies (10,11).A missense mutation in the LS gene of Arabidopsis caused only a partial reduction of AGPase activity and starch levels in leaves (12). The isolated enzyme, which was found to be composed of only the SS, required much higher levels of 3-PGA for activation as compared with the wild-type (wild type) Arabidopsis leaf AGPase (13).…”

mentioning

confidence: 75%

Analysis of Allosteric Effector Binding Sites of Potato ADP-glucose Pyrophosphorylase through Reverse Genetics

Kavaklı

Park

Slattery

et al. 2001

Journal of Biological Chemistry

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ADP-glucose pyrophosphorylase (AGPase) is a key regulatory enzyme of bacterial glycogen and plant starch synthesis as it controls carbon flux via its allosteric regulatory behavior. Unlike the bacterial enzyme that is composed of a single subunit type, the plant AGPase is a heterotetrameric enzyme (␣ 2 ␤ 2 ) with distinct roles for each subunit type. The large subunit (LS) is involved mainly in allosteric regulation through its interaction with the catalytic small subunit (SS). The LS modulates the catalytic activity of the SS by increasing the allosteric regulatory response of the hetero-oligomeric enzyme. To identify regions of the LS involved in binding of effector molecules, a reverse genetics approach was employed. A potato (Solanum tuberosum L.) AGPase LS down-regulatory mutant (E38A) was subjected to random mutagenesis using error-prone polymerase chain reaction and screened for the capacity to form an enzyme capable of restoring glycogen production in glgC ؊ Escherichia coli. Dominant mutations were identified by their capacity to restore glycogen production when the LS containing only the second site mutations was co-expressed with the wild-type SS. Sequence analysis showed that most of the mutations were decidedly nonrandom and were clustered at conserved N-and C-terminal regions. Kinetic analysis of the dominant mutant enzymes indicated that the K m values for cofactor and substrates were comparable with the wildtype AGPase, whereas the affinities for activator and inhibitor were altered appreciably. These AGPase variants displayed increased resistance to P i inhibition and/or greater sensitivity toward 3-phosphoglyceric acid activation. Further studies of Lys-197, Pro-261, and Lys-420, residues conserved in AGPase sequences, by site-directed mutagenesis suggested that the effectors 3-phosphoglyceric acid and P i interact at two closely located binding sites.ADP-glucose pyrophosphorylase (AGPase) 1 controls the synthesis of glycogen and starch in bacteria and plants, respectively. It catalyzes the formation of ADP-glucose from glucose 1-phosphate (Glc-1-P) and ATP with the concomitant release of pyrophosphate (PP i ) (1-3). The product ADP-glucose then serves as the glucosyl donor for the formation of ␣-1,4-glucosyl chains by glycogen/starch synthase. Both bacterial and plant AGPases are allosterically regulated by small effector molecules whose nature reflects the primary carbon assimilatory pathway present in these organisms. Despite sharing sequence homology and similar catalytic and regulatory properties, the bacterial and plant AGPases have different quaternary structures. The bacterial AGPases are composed of four identical subunits with an approximate subunit molecular mass of 48 kDa (4). In contrast, the heterotetrameric plant enzyme is composed of a pair of large (LS) and small subunits (SS), encoded by different genes. The molecular mass of the plant LSs range from 51 to 60 kDa, whereas the SSs are from 50 to 54 kDa (5, 6).Different approaches have been utilized in attempts to decipher the r...

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mentioning

confidence: 75%

Analysis of Allosteric Effector Binding Sites of Potato ADP-glucose Pyrophosphorylase through Reverse Genetics

Kavaklı

Park

Slattery

et al. 2001

Journal of Biological Chemistry

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“…The posttranslational control of many enzymes involved in starch biosynthesis has been well documented [13–15]. In contrast, the transcriptional regulation of the genes coding for these enzymes has not yet been fully explored.…”

Section: Introductionmentioning

confidence: 99%

Transcriptomic Analysis of Starch Biosynthesis in the Developing Grain of Hexaploid Wheat

Stamova

Laudencia‐Chingcuanco

Beckles

2009

International Journal of Plant Genomics

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The expression of genes involved in starch synthesis in wheat was analyzed together with the accumulation profiles of soluble sugars, starch, protein, and starch granule distribution in developing caryopses obtained from the same biological materials used for profiling of gene expression using DNA microarrays. Multiple expression patterns were detected for the different starch biosynthetic gene isoforms, suggesting their relative importance through caryopsis development. Members of the ADP-glucose pyrophosphorylase, starch synthase, starch branching enzyme, and sucrose synthase gene families showed different expression profiles; expression of some members of these gene families coincided with a period of high accumulation of starch while others did not. A biphasic pattern was observed in the rates of starch and protein accumulation which paralleled changes in global gene expression. Metabolic and regulatory genes that show a pattern of expression similar to starch accumulation and granule size distribution were identified, suggesting their coinvolvement in these biological processes.

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“…This enzyme catalyzes the reversible synthesis of ADP-glucose which serves as a glucosyl donor and PPi from ATP and glucose-1-phosphate (G-1-P) in the presence of a divalent metal ion. Its regulatory and catalytic properties from several sources have been extensively reviewed by Preiss et al [8]. It is generally thought that AGPase is commonly modulated by allosteric effectors and exists in a tetrameric structure [7].…”

Section: Introductionmentioning

confidence: 99%

“…It is generally thought that AGPase is commonly modulated by allosteric effectors and exists in a tetrameric structure [7]. However, much difference in the allosteric properties and structure of the protein is seen between the higher plant and bacterial enzymes [5,6,8]. The enzyme from bacteria is a homotetramer with a molecular mass of 200 kDa, encoded by a single gene locus [7], while the higher plant enzymes have a more complex heterotetrameric structure with two dissimilar subunits [9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Alteration of the substrate specificity of Thermus caldophilus ADP-glucose pyrophosphorylase by random mutagenesis through error-prone polymerase chain reaction

et al. 2006

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Expanding the scope of stereoselectivity is of current interest in enzyme catalysis. In this study, using error-prone polymerase chain reaction (PCR), a thermostable adenosine diphosphate (ADP)-glucose pyrophosphorylase (AGPase) from Thermus caldophilus GK-24 has been altered to improve its catalytic activity toward enatiomeric substrates including [glucose-1-phosphate (G-1-P) + uridine triphosphate (UTP)] and [N-acetylglucosamine-1-phosphate (GlcNAc) + UTP] to produce uridine diphosphate (UDP)-glucose and UDP-N-acetylglucosamine, respectively. To elucidate the amino acids responsible for catalytic activity, screening for UDP-glucose pyrophosphorylase (UGPase) and UDP-N-acetylglucosamine pyrophosphorylase (UNGPase) activities was carried out. Among 656 colonies, two colonies showed UGPase activities and three colonies for UNGPase activities. DNA sequence analyses and enzyme assays showed that two mutant clones (H145G) specifically have an UGPase activity, indicating that the changed glycine residue from histidine has the base specificity for UTP. Also, three double mutants (H145G/A325V) showed a UNGPase, and A325 was associated with sugar binding, conferring the specificity for the sugar substrates and V325 of the mutant appears to be indirectly involved in the binding of the N-acetylamine group of N-acetylglucosmine-1-phosphate.

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Starch biosynthesis and its regulation

Cited by 94 publications

References 3 publications

Analysis of Allosteric Effector Binding Sites of Potato ADP-glucose Pyrophosphorylase through Reverse Genetics

Analysis of Allosteric Effector Binding Sites of Potato ADP-glucose Pyrophosphorylase through Reverse Genetics

Transcriptomic Analysis of Starch Biosynthesis in the Developing Grain of Hexaploid Wheat

Alteration of the substrate specificity of Thermus caldophilus ADP-glucose pyrophosphorylase by random mutagenesis through error-prone polymerase chain reaction

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