Crystal structure of amylomaltase from Thermus aquaticus, a glycosyltransferase catalysing the production of large cyclic glucans

Przylas, Ingo; Tomoo, Koji; Terada, Yukimasa; Takaha, Takeshi; Fujii, Kazutoshi; Saenger, Wolfram; Sträter, Norbert

doi:10.1006/jmbi.1999.3503

Cited by 100 publications

(166 citation statements)

References 60 publications

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“…When compared with the analogue values in AMY1 D180A -acarbose, ⌽ and ⌿ are rather similar between subsites Ϫ3 to Ϫ1 as expected. However, when approaching the nonreducing end of the glycone part of the active site, only ⌽,⌿ values between subsites Ϫ2 to Ϫ1 are similar to the analogue ones as found in other complexes (47). Hereafter they differ, which is particularly remarkable when comparing to (⌽,⌿) for the interglycosidic bond between subsites Ϫ3 to Ϫ2 in the B. subtilis ␣-amylase-maltopentaose structure (16) being (123°,Ϫ107°).…”

Section: Amy1 In Complex With Acarbose and Comparison With Amy2-acarbmentioning

confidence: 70%

“…Amylomaltase is a member of GH 77, which together with GH 13 is a part of the clan H. It catalyzes either the transglycosylation with transfer from one ␣-1,4-glucan to another or an intramolecular cyclization resulting in much larger cyclodextrins than produced by CGTases. Two acarbose molecules are bound in this structure (47), one in the active site and a second close to the active center at a distance of 14 Å. In this latter site, key interactions determining the conformation and bind-ing of the inhibitor are the hydrophobic contacts of Tyr-54 and Tyr-101 with unit C from acarbose.…”

Section: Discussionmentioning

confidence: 99%

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Oligosaccharide Binding to Barley α-Amylase 1

Robert

Haser

Mori

et al. 2005

Journal of Biological Chemistry

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Enzymatic subsite mapping earlier predicted 10 binding subsites in the active site substrate binding cleft of barley ␣-amylase isozymes. The three-dimensional structures of the oligosaccharide complexes with barley ␣-amylase isozyme 1 (AMY1) described here give for the first time a thorough insight into the substrate binding by describing residues defining 9 subsites, namely ؊7 through ؉2. These structures support that the pseudotetrasaccharide inhibitor acarbose is hydrolyzed by the active enzymes. Moreover, sugar binding was observed to the starch granule-binding site previously determined in barley ␣-amylase isozyme 2 (AMY2), and the sugar binding modes are compared between the two isozymes. The "sugar tongs" surface binding site discovered in the AMY1-thio-DP4 complex is confirmed in the present work. A site that putatively serves as an entrance for the substrate to the active site was proposed at the glycone part of the binding cleft, and the crystal structures of the catalytic nucleophile mutant (AMY1 D180A ) complexed with acarbose and maltoheptaose, respectively, suggest an additional role for the nucleophile in the stabilization of the Michaelis complex. Furthermore, probable roles are outlined for the surface binding sites. Our data support a model in which the two surface sites in AMY1 can interact with amylose chains in their naturally folded form. Because of the specificities of these two sites, they may locate/orient the enzyme in order to facilitate access to the active site for polysaccharide chains. Moreover, the sugar tongs surface site could also perform the unraveling of amylose chains, with the aid of Tyr-380 acting as "molecular tweezers."

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Section: Amy1 In Complex With Acarbose and Comparison With Amy2-acarbmentioning

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Oligosaccharide Binding to Barley α-Amylase 1

Robert

Haser

Mori

et al. 2005

Journal of Biological Chemistry

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“…19) The result indicated that the 460s loop may also prevent the production of small cyclic glucans, as is the case with 4 GT from Thermococcus litoralis. The crystal structure of Taq amylomaltase in complex with acarboses has also been analyzed and showed the presence of two acarbose binding sites in this enzyme 20) , where one is in the active site and the second one is located around tyrosine 54 (Y54), which is 14A away from the catalytic site (Fig.…”

Section: Improvement Of Amylomaltase From Thermus Aquaticus By Randommentioning

confidence: 94%

Improvement of Amylomaltase from Thermus aquaticus by Random and Saturation Mutageneses

et al. 2005

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“…3). 22) The tryptic peptides derived from the 60-kDa polypeptide were assigned to 47% of the deduced DPE1 sequence (Fig. 2B and C), whereas no tryptic peptide derived from the 50-kDa polypeptide accorded with the sequence.…”

Section: Characterization Of Dpe1mentioning

confidence: 94%