1RPK

Crystal structure of barley alpha-amylase isozyme 1 (amy1) in complex with acarbose


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.180 

Starting Model: experimental
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This is version 2.1 of the entry. See complete history


Literature

Oligosaccharide Binding to Barley {alpha}-Amylase 1

Robert, X.Haser, R.Mori, H.Svensson, B.Aghajari, N.

(2005) J Biol Chem 280: 32968-32978

  • DOI: https://doi.org/10.1074/jbc.M505515200
  • Primary Citation of Related Structures:  
    1RP8, 1RP9, 1RPK

  • PubMed Abstract: 

    Enzymatic subsite mapping earlier predicted 10 binding subsites in the active site substrate binding cleft of barley alpha-amylase isozymes. The three-dimensional structures of the oligosaccharide complexes with barley alpha-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 alpha-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 (AMY1D180A) 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."


  • Organizational Affiliation

    Laboratoire de BioCristallographie, IFR-128 BioSciences Lyon-Gerland, Institut de Biologie et Chimie des Protéines, UMR 5086, CNRS-UCBL1, 7 Passage du Vercors, F-69367 Lyon Cedex 07, France.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Alpha-amylase type 1 isozyme405Hordeum vulgareMutation(s): 0 
Gene Names: AMY1.1
EC: 3.2.1.1
UniProt
Find proteins for P00693 (Hordeum vulgare)
Explore P00693 
Go to UniProtKB:  P00693
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00693
Sequence Annotations
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  • Reference Sequence
Oligosaccharides

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Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
4,6-dideoxy-4-{[(1S,5R,6S)-3-formyl-5,6-dihydroxy-4-oxocyclohex-2-en-1-yl]amino}-alpha-D-xylo-hex-5-enopyranose-(1-4)-alpha-D-glucopyranose
B, D
2N/AN/A
Entity ID: 3
MoleculeChains Length2D Diagram Glycosylation3D Interactions
4,6-dideoxy-4-{[(1S,5R,6S)-3-formyl-5,6-dihydroxy-4-oxocyclohex-2-en-1-yl]amino}-alpha-D-xylo-hex-5-enopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose
C
3N/AN/A
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.180 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 93.39α = 90
b = 72.92β = 90
c = 61.39γ = 90
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
CCP4data scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-06-07
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Atomic model, Data collection, Derived calculations, Structure summary
  • Version 2.1: 2023-08-23
    Changes: Data collection, Database references, Refinement description, Structure summary