An Amylose Antiparallel Double Helix at Atomic Resolution

Hinrichs, W.; Büttner, G.; Steifa, Manfred; Betzel, C.; Zabel, V.; Pfannemüller, B.; Saenger, Wolfram

doi:10.1126/science.238.4824.205

Cited by 94 publications

(57 citation statements)

References 27 publications

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“…The coordination of the water molecules to CA26 follows patterns that have been observed previously (9,10,12,18). The most prominent motifs are five-membered rings formed by water molecules coordinated in bidentate mode to O(2) and O(3) and͞or to O(5) and O(6) belonging to the same glucose.…”

Section: Resultssupporting

confidence: 66%

“…Since crystallization of amylose fragments with defined chain lengths has remained elusive, structural information relies on x-ray fiber diffraction, electron diffraction on tiny single crystals, and solid-state 13 C cross-polarization͞magic angle spinning (CP͞MAS) NMR spectroscopy combined with computer-aided modeling (3)(4)(5)(6)(7)(8). The only available single crystal x-ray study of an amylose-type oligosaccharide in the complex (p-nitrophenyl ␣-maltohexaoside) 2 ⅐Ba(I 3 ) 2 ⅐27H 2 O features an antiparallel left-handed double helix (9,10) that has no resemblance to A-, B-, or V-amylose.…”

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confidence: 99%

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V-Amylose at atomic resolution: X-ray structure of a cycloamylose with 26 glucose residues (cyclomaltohexaicosaose)

Geßler

Usón

Takaha

et al. 1999

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

210

160

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The amylose fraction of starch occurs in double-helical A-and B-amyloses and the single-helical V-amylose. The latter contains a channel-like central cavity that is able to include molecules, ''iodine's blue'' being the best-known representative. Molecular models of these amylose forms have been deduced by solid state 13 C cross-polarization͞magic angle spinning NMR and by x-ray fiber and electron diffraction combined with computer-aided modeling. They remain uncertain, however, as no structure at atomic resolution is available. We report here the crystal structure of a hydrated cycloamylose containing 26 glucose residues (cyclomaltohexaicosaose, CA26), which has been determined by real͞reciprocal space recycling starting from randomly positioned atoms or from an oriented diglucose fragment. This structure provides conclusive evidence for the structure of V-amylose, as the macrocycle of CA26 is folded into two short left-handed V-amylose helices in antiparallel arrangement and related by twofold rotational pseudosymmetry. In the V-helices, all glucose residues are in syn orientation, forming systematic interglucose O(3) n ⅐⅐⅐O(2) n؉l and O(6) n ⅐⅐⅐O (2) Starch is composed of two fractions, the linear amylose consisting exclusively of ␣(1-4)-linked glucose residues in 4 C 1 -chair conformation, and the branched amylopectin, which also contains ␣(1-6) links at characteristic intervals. The polysaccharide chain of amylose may be folded into three different structures denoted A, B, and V (1-3). Since crystallization of amylose fragments with defined chain lengths has remained elusive, structural information relies on x-ray fiber diffraction, electron diffraction on tiny single crystals, and solid-state 13 C cross-polarization͞magic angle spinning (CP͞MAS) NMR spectroscopy combined with computer-aided modeling (3-8). The only available single crystal x-ray study of an amylose-type oligosaccharide in the complex (p-nitrophenyl ␣-maltohexaoside) 2 ⅐Ba(I 3 ) 2 ⅐27H 2 O features an antiparallel left-handed double helix (9, 10) that has no resemblance to A-, B-, or V-amylose.The structures of A-and B-amylose are similar and differ only in packing arrangement and water content, the A-form occurring preferentially in cereals and the B-form in tubers (3). They both form double helices with parallel strands of 6 ϫ 2 glucoses per turn and right-handed (3-8) or left-handed (11) twist, this ambiguity illustrating the weakness of the above methods, which do not provide structural information at atomic resolution.The polysaccharide chain of V-amylose found naturally in non-A and non-B segments of amylose is folded into a lefthanded single helix; it contains 6 glucoses per turn with 7.91-to 8.17-Å pitch height (3-5) and forms a central channel-like cavity.

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Section: Resultssupporting

confidence: 66%

mentioning

confidence: 99%

V-Amylose at atomic resolution: X-ray structure of a cycloamylose with 26 glucose residues (cyclomaltohexaicosaose)

Geßler

Usón

Takaha

et al. 1999

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

210

160

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“…In addition, all glucoses assume a favorable 4 C 1 chair conformation, except for those that bind in subsite Ϫ1 (7). However, the internal hydrogen bond network between the glucose OH-2 and OH-3 groups, which is observed in both free cyclodextrins (24,31) and free starch (32), is broken between subsites Ϫ1/ϩ1 and ϩ1/ϩ2 (see Table III and Fig. 5).…”

Section: Resultsmentioning

confidence: 99%

The Cyclization Mechanism of Cyclodextrin Glycosyltransferase (CGTase) as Revealed by a γ-Cyclodextrin-CGTase Complex at 1.8-Å Resolution

Uitdehaag¹,

Kalk²,

Veen³

et al. 1999

Journal of Biological Chemistry

124

134

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The enzyme cyclodextrin glycosyltransferase is closely related to ␣-amylases but has the unique ability to produce cyclodextrins (circular ␣(134)-linked glucoses) from starch. To characterize this specificity we determined a 1.8-Å structure of an E257Q/D229N mutant cyclodextrin glycosyltransferase in complex with its product ␥-cyclodextrin, which reveals for the first time how cyclodextrin is competently bound. Across subsites ؊2, ؊1, and ؉1, the cyclodextrin ring binds in a twisted mode similar to linear sugars, giving rise to deformation of its circular symmetry. At subsites ؊3 and ؉2, the cyclodextrin binds in a manner different from linear sugars. Sequence comparisons and site-directed mutagenesis experiments support the conclusion that subsites ؊3 and ؉2 confer the cyclization activity in addition to subsite ؊6 and Tyr-195. On this basis, a role of the individual residues during the cyclization reaction cycle is proposed.

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“…9 shows that either conformation in linear amylose could potentially allow cyclization to form cycloamylose in either configuration. The Monte Carlo simulation suggested that the antiparallel double helix structure is the most likely conformation of amylose in solution (21), and crystallographic analysis has shown that linear amylose with a DP of 6 adopts a left-handed antiparallel double helix conformation (22,23). It can be seen how such a conformation would readily allow cyclization by D-enzyme since donor and acceptor sites of amylose are juxtaposed (Fig.…”

Section: Figmentioning

confidence: 99%

Potato D-enzyme Catalyzes the Cyclization of Amylose to Produce Cycloamylose, a Novel Cyclic Glucan

Takaha

Yanase

Takata

et al. 1996

Journal of Biological Chemistry

191

162

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Potato D-enzyme was purified from recombinant Escherichia coli, and its action on synthetic amylose (average M r of 320,000) was analyzed. D-enzyme treatment resulted in a decrease in the ability of the amylose to form a blue complex with iodine. Analysis of the products indicated that the enzyme catalyzes an intramolecular transglycosylation reaction on amylose to produce cyclic ␣-1,4-glucan (cycloamylose). Confirmation of the cyclic structure was achieved by demonstrating the absence of reducing and nonreducing ends, resistance to hydrolysis by glucoamylase (an exoamylase), and by "time of flight" mass spectrometry. The degree of polymerization of cycloamylose products was determined by time of flight mass spectrometry analysis and by highperformance anion-exchange chromatography following partial acid hydrolysis of purified cycloamylose molecules and was found to range from 17 to several hundred. The yield of cycloamylose increased with time and reached >95%. D-enzyme did not act upon purified cycloamylose, but if glucose was added as an acceptor molecule, smaller cyclic and linear molecules were produced. The mechanism of the cyclization reaction, the possible role of the enzyme in starch metabolism, and the potential applications for cycloamylose are discussed.

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An Amylose Antiparallel Double Helix at Atomic Resolution

Cited by 94 publications

References 27 publications

V-Amylose at atomic resolution: X-ray structure of a cycloamylose with 26 glucose residues (cyclomaltohexaicosaose)

V-Amylose at atomic resolution: X-ray structure of a cycloamylose with 26 glucose residues (cyclomaltohexaicosaose)

The Cyclization Mechanism of Cyclodextrin Glycosyltransferase (CGTase) as Revealed by a γ-Cyclodextrin-CGTase Complex at 1.8-Å Resolution

Potato D-enzyme Catalyzes the Cyclization of Amylose to Produce Cycloamylose, a Novel Cyclic Glucan

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