The Role of Pullulanase in Starch Biosynthesis, Structure, and Thermal Properties by Studying Sorghum with Increased Pullulanase Activity

Li, Enpeng; Hasjim, Jovin; Gilding, Edward K.; Godwin, Ian D.; Li, Cheng; Gilbert, Robert G.

doi:10.1002/star.201900072

Cited by 10 publications

(4 citation statements)

References 32 publications

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“…The major function of LDA, and an ISA-type DBE isoform termed ISA3 is removal of α-(1,6)-branch linkages from chains released during starch degradation [ 233 , 234 , 235 ]. Any role LDA may play in defining amylopectin structure during synthesis is not clear, although it may be involved in debranching amylose chains in rice endosperm [ 236 ]. The precise structural nature of the substrates for these DBEs in vivo is not clear, and there appears to be functional overlap between the different isoforms [ 234 , 237 , 238 ].…”

Section: Amylopectin Synthesismentioning

confidence: 99%

A Review of Starch Biosynthesis in Relation to the Building Block-Backbone Model

Tetlow

Bertoft²

2020

IJMS

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Starch is a water-insoluble polymer of glucose synthesized as discrete granules inside the stroma of plastids in plant cells. Starch reserves provide a source of carbohydrate for immediate growth and development, and act as long term carbon stores in endosperms and seed tissues for growth of the next generation, making starch of huge agricultural importance. The starch granule has a highly complex hierarchical structure arising from the combined actions of a large array of enzymes as well as physicochemical self-assembly mechanisms. Understanding the precise nature of granule architecture, and how both biological and abiotic factors determine this structure is of both fundamental and practical importance. This review outlines current knowledge of granule architecture and the starch biosynthesis pathway in relation to the building block-backbone model of starch structure. We highlight the gaps in our knowledge in relation to our understanding of the structure and synthesis of starch, and argue that the building block-backbone model takes accurate account of both structural and biochemical data.

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Section: Amylopectin Synthesismentioning

confidence: 99%

A Review of Starch Biosynthesis in Relation to the Building Block-Backbone Model

Tetlow

Bertoft²

2020

IJMS

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“…However, a small proportion of BE is also granule bound (Denyer & Smith, 1992; Tetlow et al ., 2004; Liu et al ., 2012b), and could be involved in branching amylose. Interestingly, sorghum lines with varying pullulanase activity were recently reported to have significant changes in amylose structure, suggesting that debranching activities can also contribute to amylose structure (Li et al ., 2019b).…”

Section: Amylose Structurementioning

confidence: 99%

Amylose in starch: towards an understanding of biosynthesis, structure and function

Seung

2020

New Phytologist

147

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Summary Starch granules are composed of two distinct glucose polymers – amylose and amylopectin. Amylose constitutes 5–35% of most natural starches and has a major influence over starch properties in foods. Its synthesis and storage occurs within the semicrystalline amylopectin matrix of starch granules, this poses a great challenge for biochemical and structural analyses. However, the last two decades have seen vast progress in understanding amylose synthesis, including new insights into the action of GRANULE BOUND STARCH SYNTHASE (GBSS), the major glucosyltransferase that synthesises amylose, and the discovery of PROTEIN TARGETING TO STARCH1 (PTST1) that targets GBSS to starch granules. Advances in analytical techniques have resolved the fine structure of amylose, raising new questions on how structure is determined during biosynthesis. Furthermore, the discovery of wild plants that do not produce amylose revives a long‐standing question of why starch granules contain amylose, rather than amylopectin alone. Overall, these findings contribute towards a full understanding of amylose biosynthesis, structure and function that will be essential for future approaches to improve starch quality in crops.

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“…Some of these enzymes have been cloned, expressed, and characterised (Tappiban et al, 2019), such as DPE1 (Tantanarat et al, 2014), ISA1/ISA2 (Panpetch et al, 2018b), and ISA3 (Panpetch et al, 2018a). Notably, most studies of plant pullulanases have been conducted in vivo (Dinges et al, 2003;Fujita et al, 2009;Li et al, 2019), which is complicated by the concerted action of several other enzymes and, as a result, specific action information about individual enzymes has rarely been investigated. This study aimed to biochemically characterise pullulanase from Manihot esculenta Crantz (MePUL), with a view to determining its biological role in starch metabolism which remained unclear.…”

Section: Introductionmentioning

confidence: 99%

Cassava pullulanase and its synergistic debranching action with isoamylase 3 in starch catabolism

et al. 2023

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Pullulanase (EC 3.2.1.41, PUL), a debranching enzyme belonging to glycoside hydrolase family 13 subfamily 13, catalyses the cleavage of α-1,6 linkages of pullulan and β-limit dextrin. The present work studied PUL from cassava Manihot esculenta Crantz (MePUL) tubers, an important economic crop. The Mepul gene was successfully cloned and expressed in E. coli and rMePUL was biochemically characterised. MePUL was present as monomer and homodimer, as judged by apparent mass of ~ 84 - 197 kDa by gel permeation chromatography analysis. Optimal pH and temperature were at pH 6.0 and 50 °C, and enzyme activity was enhanced by the addition of Ca2+ ions. Pullulan is the most favourable substrate for rMePUL, followed by β-limit dextrin. Additionally, maltooligosaccharides were potential allosteric modulators of rMePUL. Interestingly, short-chain maltooligosaccharides (DP 2 - 4) were significantly revealed at a higher level when rMePUL was mixed with cassava isoamylase 3 (rMeISA3), compared to that of each single enzyme reaction. This suggests that MePUL and MeISA3 debranch β-limit dextrin in a synergistic manner, which represents a major starch catabolising process in dicots. Additionally, subcellular localisation suggested the involvement of MePUL in starch catabolism, which normally takes place in plastids.

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The Role of Pullulanase in Starch Biosynthesis, Structure, and Thermal Properties by Studying Sorghum with Increased Pullulanase Activity

Cited by 10 publications

References 32 publications

A Review of Starch Biosynthesis in Relation to the Building Block-Backbone Model

A Review of Starch Biosynthesis in Relation to the Building Block-Backbone Model

Amylose in starch: towards an understanding of biosynthesis, structure and function

Cassava pullulanase and its synergistic debranching action with isoamylase 3 in starch catabolism

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