2012
DOI: 10.1042/bj20120573
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Glucan affinity of starch synthase IIa determines binding of starch synthase I and starch-branching enzyme IIb to starch granules

Abstract: The sugary-2 mutation in maize (Zea mays L.) is a result of the loss of catalytic activity of the endosperm-specific SS (starch synthase) IIa isoform causing major alterations to amylopectin architecture. The present study reports a biochemical and molecular analysis of an allelic variant of the sugary-2 mutation expressing a catalytically inactive form of SSIIa and sheds new light on its central role in protein-protein interactions and determination of the starch granule proteome. The mutant SSIIa revealed tw… Show more

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Cited by 95 publications
(102 citation statements)
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“…Tetlow and Emes amylopectin cluster biosynthesis, given the substrate preferences of the individual enzymes and the fact that all three enzymes in the isolated complex remain catalytically active (17). Evidence from developing wheat endosperm suggests that SBEII isoforms in the trimeric protein complex have greater affinity for amylopectin, the presumptive substrate (9).…”
Section: Figmentioning
confidence: 99%
See 1 more Smart Citation
“…Tetlow and Emes amylopectin cluster biosynthesis, given the substrate preferences of the individual enzymes and the fact that all three enzymes in the isolated complex remain catalytically active (17). Evidence from developing wheat endosperm suggests that SBEII isoforms in the trimeric protein complex have greater affinity for amylopectin, the presumptive substrate (9).…”
Section: Figmentioning
confidence: 99%
“…The components of the trimeric SSI/SSIIa/SBEIIb protein complex eventually become entrapped within the starch granule through the glucan-binding capacity of SSIIa (17). SBEIIb has also been detected in a protein complex with SBEI and SP (E.C.…”
Section: Figmentioning
confidence: 99%
“…In ae1.2, the internal granule-bound components consist of SSI, SSIIa, SBEI, SBEIIa, and null SBEIIb. The starch of ae1.2 has much lower apparent amylose and fewer intermediate-length glucan chains than does that of ae 2 and has altered granule morphology that is distinctly different from that of both the ae 2 mutant and the wild type (Liu et al, 2012b). Only seven amylopectin biosynthetic enzymes, SSI, SSIIa, SSIIIa, SBEI, SBEIIa, SBEIIb, and Pho1, are capable of binding to the starch granule in the wild type and various mutants, although there are more than seven enzyme proteins responsible for amylopectin formation (Grimaud et al, 2008).…”
Section: Granule-bound Amylopectin Biosynthetic Enzymes Are An Importmentioning
confidence: 99%
“…Two maize ae mutations lead to the absence of SBEIIb in ae 2 (ae1.1) and a catalytically inactive form of SBEIIb in ae1.2. The different mutation patterns cause different granule-bound protein compositions, even though the primary cause of the mutation, the loss of SBEIIb activity, is the same (Liu et al, 2009(Liu et al, , 2012b. A novel protein complex formed in the stroma that includes SBEI, SBEIIa, Pho1, SSI, and SSIIa effectively becomes localized to starch granules in ae 2 (Liu et al, 2009).…”
Section: Granule-bound Amylopectin Biosynthetic Enzymes Are An Importmentioning
confidence: 99%
“…Three phosphorylation sites (Ser286, Ser297 and Ser649) were then experimentally identified in maize SBEIIb, with Ser286 and Ser297 conserved among cereal SBEIIs [128]. Maize SSIIa was found at the centre of a trimeric enzyme complex of SSI and SBEIIb both within the stroma and granule, and it conferred starch binding properties to the complex [129]. According to the specificities of individual isozymes, this complex was proposed to contribute to the synthesis of short and intermediate amylopectin branches to form the crystalline lamellae [127,130].…”
Section: Enzyme Complexesmentioning
confidence: 99%