Influence of the naturally occurring phosphate esters on the crystallinity of potato starch

Muhrbeck, Per; Eliasson, Ann‐Charlotte

doi:10.1002/jsfa.2740550103

Cited by 59 publications

(28 citation statements)

References 11 publications

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“…This strongly supports the previously reported direct correlation between the degree of phosphorylation of native potato starches and their sensitivity to annealing [1]. The findings also support the view that the phosphate esters present in potato starch have an influence on the crystallinity [11,21].…”

Section: Discussionsupporting

confidence: 89%

Influence of Phosphate Esters on the Annealing Properties of Starch

Muhrbeck¹,

Wischmann

1998

Starch/Stärke

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the onset temperature change was much larger in potato starch than in the two waxy maize starches. Steeping also yielded intermediate effects on the phosphorylated waxy maize starch. It was concluded that the phosphate groups have similar effects as they do in the native, naturally phosphorylated potato starch, although the substitution pattern is not entirely the same in the artificially phosphorylated starch.

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Section: Discussionsupporting

confidence: 89%

Influence of Phosphate Esters on the Annealing Properties of Starch

Muhrbeck¹,

Wischmann

1998

Starch/Stärke

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“…The myriad food and nonfood starchbased industrial products require enzymatic and chemical modification of starch to generate necessary starch-based feedstocks (48)(49)(50). Phosphorylation is the only known natural modification of starch, and has direct influences on starch hydration, crystallinity, freeze-thaw stability, viscosity, and transparency that are central to various commercial applications (39)(40)(41). Furthermore, it is clear that C6 and C3 phosphorylation of starch influence its properties differently, as studies show that C3 phosphate has a more direct effect on starch granule solubilization (14).…”

Section: Discussionmentioning

confidence: 99%

“…These phosphorylation events are critical for normal transitory starch degradation, but also directly impact the melting temperature, viscosity, and hydration of starch in industrial settings (39,40). Developing a means to manipulate starch phosphorylation patterns via enzymatic modification is relevant to agricultural and industrial applications that use starch as a feedstock (9,12,14,41).…”

mentioning

confidence: 99%

Phosphoglucan-bound structure of starch phosphatase Starch Excess4 reveals the mechanism for C6 specificity

Meekins

Raththagala

Husodo

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

123

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Plants use the insoluble polyglucan starch as their primary glucose storage molecule. Reversible phosphorylation, at the C6 and C3 positions of glucose moieties, is the only known natural modification of starch and is the key regulatory mechanism controlling its diurnal breakdown in plant leaves. The glucan phosphatase Starch Excess4 (SEX4) is a position-specific starch phosphatase that is essential for reversible starch phosphorylation; its absence leads to a dramatic accumulation of starch in Arabidopsis, but the basis for its function is unknown. Here we describe the crystal structure of SEX4 bound to maltoheptaose and phosphate to a resolution of 1.65 Å. SEX4 binds maltoheptaose via a continuous binding pocket and active site that spans both the carbohydrate-binding module (CBM) and the dual-specificity phosphatase (DSP) domain. This extended interface is composed of aromatic and hydrophilic residues that form a specific glucan-interacting platform. SEX4 contains a uniquely adapted DSP active site that accommodates a glucan polymer and is responsible for positioning maltoheptaose in a C6-specific orientation. We identified two DSP domain residues that are responsible for SEX4 sitespecific activity and, using these insights, we engineered a SEX4 double mutant that completely reversed specificity from the C6 to the C3 position. Our data demonstrate that the two domains act in consort, with the CBM primarily responsible for engaging glucan chains, whereas the DSP integrates them in the catalytic site for position-specific dephosphorylation. These data provide important insights into the structural basis of glucan phosphatase site-specific activity and open new avenues for their biotechnological utilization.tarch is the primary carbohydrate storage molecule in plants and is an essential constituent of human and animal diets. Starch granules are composed of the glucose homopolymers amylose (10-25%) and amylopectin (75-90%) (1, 2). Amylose is a linear molecule formed from α-1,4-glycosidic-linked chains, whereas amylopectin is formed from α-1,4-glycosidic-linked chains with α-1,6-glycosidic-linked branches (3, 4). Adjacent amylopectin chains interact to form double helices that cause starch granules to be water insoluble, which is an essential feature for its function as a glucose storage molecule (1, 3, 5). However, the outer granular surface of transitory starch must be solubilized during nonphotosynthetic periods so that glycolytic enzymes can access and degrade starch glucans and meet the metabolic needs of the plant (6, 7). Plants regulate the solubility of the starch granular surface via reversible starch phosphorylation that results in a cyclic degradative process: phosphorylation by dikinases, degradation by starch hydrolyzing amylases, and dephosphorylation by phosphatases (1, 8-11). Phosphorylation of amylopectin chains causes helical unwinding and local solubilization of the outer starch granule (12-14). The local solubilization and helix unwinding permits degradation of surface, linear α-1,4 glucan chai...

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“…Starch is used in countless applications, many of which require chemical and physical modifications to improve and diversify its functionality (Blennow et al, 2002;. Phosphorylation is the only known natural modification of starch, and highly phosphorylated starches have many attractive characteristics, including increased hydration status (Muhrbeck and Eliasson, 1991), decreased crystallinity (Muhrbeck and Eliasson, 1991), and improved freeze-thaw stability, viscosity, and transparency (Blennow et al, 2001). Arabidopsis plants lacking LSF2 activity display increased C3-phosphorylated starch without adverse effects on plant growth .…”

Section: Discussionmentioning

confidence: 99%

Structure of the Arabidopsis Glucan Phosphatase LIKE SEX FOUR2 Reveals a Unique Mechanism for Starch Dephosphorylation

et al. 2013

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Starch is a water-insoluble, Glc-based biopolymer that is used for energy storage and is synthesized and degraded in a diurnal manner in plant leaves. Reversible phosphorylation is the only known natural starch modification and is required for starch degradation in planta. Critical to starch energy release is the activity of glucan phosphatases; however, the structural basis of dephosphorylation by glucan phosphatases is unknown. Here, we describe the structure of the Arabidopsis thaliana starch glucan phosphatase LIKE SEX FOUR2 (LSF2) both with and without phospho-glucan product bound at 2.3Å and 1.65Å, respectively. LSF2 binds maltohexaose-phosphate using an aromatic channel within an extended phosphatase active site and positions maltohexaose in a C3-specific orientation, which we show is critical for the specific glucan phosphatase activity of LSF2 toward native Arabidopsis starch. However, unlike other starch binding enzymes, LSF2 does not possess a carbohydrate binding module domain. Instead we identify two additional glucan binding sites located within the core LSF2 phosphatase domain. This structure is the first of a glucan-bound glucan phosphatase and provides new insights into the molecular basis of this agriculturally and industrially relevant enzyme family as well as the unique mechanism of LSF2 catalysis, substrate specificity, and interaction with starch granules.

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Influence of the naturally occurring phosphate esters on the crystallinity of potato starch

Cited by 59 publications

References 11 publications

Influence of Phosphate Esters on the Annealing Properties of Starch

Influence of Phosphate Esters on the Annealing Properties of Starch

Phosphoglucan-bound structure of starch phosphatase Starch Excess4 reveals the mechanism for C6 specificity

Structure of the Arabidopsis Glucan Phosphatase LIKE SEX FOUR2 Reveals a Unique Mechanism for Starch Dephosphorylation

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