The amylose extender mutant of maize conditions novel protein-protein interactions between starch biosynthetic enzymes in amyloplasts

Liu, Fushan; Makhmoudova, Amina; Lee, Elizabeth A.; Wait, Robin; Emes, Michael J.; Tetlow, Ian J.

doi:10.1093/jxb/erp297

Cited by 144 publications

(221 citation statements)

References 60 publications

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“…In cereals, the SBEII class is subdivided into two distinct gene products, SBEIIa and SBEIIb, each with different kinetic characteristics and tissue expression patterns. SBEII isoforms transfer shorter chains (DP [6][7][8][9][10][11][12][13][14] and prefer amylopectin as a substrate (29). These characteristics have also been shown in a variety of other plant species, for example, rice (Oryza sativa L.; ref.…”

Section: Mode Of Action and Properties Of Sbesmentioning

confidence: 84%

“…SBEs are catalytically active as monomeric proteins. However, recent evidence in cereal endosperm amyloplasts indicates that they can associate with other starch biosynthetic enzymes (7,8) and can also form dimers (see "Regulation of SBE Activity" section; ref. 9.…”

Section: Mode Of Action and Properties Of Sbesmentioning

confidence: 99%

“…The precise mechanism underlying the association of specific enzymes of starch synthesis with the starch granule are not known, although it has been suggested that alternative splicing of SBEII in bean (Phaseolus vulgaris L.) leads to partitioning within the starch granule (27). Recent evidence suggests that granule-associated proteins (including the SBEII class) become entrapped in the granule through association in heteromeric protein complexes (8,53). Distinct roles for SBEI and SBEII classes in amylopectin synthesis were suggested by the analysis of glucans produced when different combinations of maize SSs and SBEs were heterologously expressed in E. coli (54).…”

Section: Tablementioning

confidence: 99%

“…The catalytic A-domain of SBEs is characterized by a symmetrical fold of eight parallel b-strands encircled by eight ahelices, which folds as a (b/a) 8 -barrel. X-ray crystallographic structures of GBE and SBE allowed elucidation of the (b/a) 8 barrel structural domain (59,61) and showed that variations occur in SBEs where the a-helix 5 is missing and replaced by extra a-helices (59).…”

Section: The Central Catalytic A-domainmentioning

confidence: 99%

“…X-ray crystallographic structures of GBE and SBE allowed elucidation of the (b/a) 8 barrel structural domain (59,61) and showed that variations occur in SBEs where the a-helix 5 is missing and replaced by extra a-helices (59). Another conserved feature of the central catalytic A-domain of SBEs is a group of four conserved amino acid regions (termed 1 to 4, see Fig.…”

Section: The Central Catalytic A-domainmentioning

confidence: 99%

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A review of starch‐branching enzymes and their role in amylopectin biosynthesis

2014

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Starch-branching enzymes (SBEs) are one of the four major enzyme classes involved in starch biosynthesis in plants and algae, and their activities play a crucial role in determining the structure and physical properties of starch granules. SBEs generate a-1,6-branch linkages in a-glucans through cleavage of internal a-1,4 bonds and transfer of the released reducing ends to C-6 hydroxyls. Starch biosynthesis in plants and algae requires multiple isoforms of SBEs and is distinct from glycogen biosynthesis in both prokaryotes and eukaryotes which uses a single branching enzyme (BE) isoform. One of the unique characteristics of starch structure is the grouping of a-1,6-branch points in clusters within amylopectin. This is a feature of SBEs and their interplay with other starch biosynthetic enzymes, thus facilitating formation of the compact water-insoluble semicrystalline starch granule. In this respect, the activity of SBE isoforms is pivotal in starch granule assembly. SBEs are structurally related to the aamylase superfamily of enzymes, sharing three domains of secondary structure with prokaryotic Bes: the central (b/a) 8 -barrel catalytic domain, an NH 2 -terminal domain involved in determining the size of a-glucan chain transferred, and the C-terminal domain responsible for catalytic capacity and substrate preference. In addition, SBEs have conserved plant-specific domains, including phosphorylation sites which are thought to be involved in regulating starch metabolism. SBEs form heteromeric protein complexes with other SBE isoforms as well as other enzymes involved in starch synthesis, and assembly of these protein complexes is regulated by protein phosphorylation. Phosphorylated SBEIIb is found in multienzyme complexes with isoforms of glucan-elongating starch synthases, and these protein complexes are implicated in amylopectin cluster formation. This review presents a comparative overview of plant SBEs and includes a review of their properties, structural and functional characteristics, and recent developments on their posttranslational regulation.

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Section: Mode Of Action and Properties Of Sbesmentioning

confidence: 84%

Section: Mode Of Action and Properties Of Sbesmentioning

confidence: 99%

Section: Tablementioning

confidence: 99%

Section: The Central Catalytic A-domainmentioning

confidence: 99%

Section: The Central Catalytic A-domainmentioning

confidence: 99%

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A review of starch‐branching enzymes and their role in amylopectin biosynthesis

2014

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Nutrient Biofortification of Staple Food Crops: Technologies, Products and Prospects

Rao¹,

Seetharam²

2017

Phytonutritional Improvement of Crops

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Non‐GMO potato lines with an altered starch biosynthesis pathway confer increased‐amylose and resistant starch properties

Krunic¹,

Skryhan²,

Mikkelsen³

et al. 2017

Starch Stärke

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The lack of a gene marker directly affecting starch biosynthesis in the potato tuber is documented. The absence of a 454 bp amplified fragment length polymorphism (AFLP) Solanum tuberosum fragment was identified in the wild potato species Solanum sandemanii and its absence results in a combined increased-amylose/high-sugar tuber chemotype. The trait is recessive, termed IAm (Increased Amylose) and was transferred to modern tetraploid S. tuberosum potato cultivars by marker-assisted crossing. Compared to controls, IAm plants had a larger number of stems and air exposed stolons, their tubers were smaller, elongated, and they were irregularly shaped. IAm starch had 28-59% higher amylose content than control starch, the starch granules were small and grossly misshaped, they had reduced crystallinity, swelling, and viscosity, reduced in vitro digestion rates with increased resistant starch fraction. The primary gene(s) responsible for the IAm phenotype is not known, but increased granule-associated phosphorylase (Pho1) and reduced starch synthase (SS) protein and enzyme activity in the IAm plants might explain the effects on starch structure. The data support the establishment of non-genetically modified crops with health-related slowly digestible carbohydrate.

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The amylose extender mutant of maize conditions novel protein-protein interactions between starch biosynthetic enzymes in amyloplasts

Cited by 144 publications

References 60 publications

A review of starch‐branching enzymes and their role in amylopectin biosynthesis

A review of starch‐branching enzymes and their role in amylopectin biosynthesis

Nutrient Biofortification of Staple Food Crops: Technologies, Products and Prospects

Non‐GMO potato lines with an altered starch biosynthesis pathway confer increased‐amylose and resistant starch properties

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