1AVA

AMY2/BASI PROTEIN-PROTEIN COMPLEX FROM BARLEY SEED


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.208 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Barley alpha-amylase bound to its endogenous protein inhibitor BASI: crystal structure of the complex at 1.9 A resolution.

Vallee, F.Kadziola, A.Bourne, Y.Juy, M.Rodenburg, K.W.Svensson, B.Haser, R.

(1998) Structure 6: 649-659

  • DOI: https://doi.org/10.1016/s0969-2126(98)00066-5
  • Primary Citation of Related Structures:  
    1AVA

  • PubMed Abstract: 

    Barley alpha-amylase is a 45 kDa enzyme which is involved in starch degradation during barley seed germination. The released sugars provide the plant embryo with energy for growth. The major barley alpha-amylase isozyme (AMY2) binds with high affinity to the endogenous inhibitor BASI (barley alpha-amylase/subtilisin inhibitor) whereas the minor isozyme (AMY1) is not inhibited. BASI is a 19.6 kDa bifunctional protein that can simultaneously inhibit AMY2 and serine proteases of the subtilisin family. This inhibitor may therefore prevent degradation of the endosperm starch during premature sprouting and protect the seed from attack by pathogens secreting proteases. The crystal structure of AMY2 in complex with BASI was determined and refined at 1.9 A resolution. BASI consists of a 12-stranded beta-barrel structure which belongs to the beta-trefoil fold family and inhibits AMY2 by sterically occluding access of the substrate to the active site of the enzyme. The AMY2-BASI complex is characterized by an unusual completely solvated calcium ion located at the protein-protein interface. The AMY2-BASI complex represents the first reported structure of an endogenous protein-protein complex from a higher plant. The structure of the complex throws light on the strict specificity of BASI for AMY2, and shows that domain B of AMY2 contributes greatly to the specificity of enzyme-inhibitor recognition. In contrast to the three-dimensional structures of porcine pancreatic alpha-amylase in complex with proteinaceous inhibitors, the AMY2-BASI structure reveals that the catalytically essential amino acid residues of the enzyme are not directly bound to the inhibitor. Binding of BASI to AMY2 creates a cavity, exposed to the external medium, that is ideally shaped to accommodate an extra calcium ion. This feature may contribute to the inhibitory effect, as the key amino acid sidechains of the active site are in direct contact with water molecules which are in turn ligated to the calcium ion.


  • Organizational Affiliation

    Macromolécules Biologiques, UPR 9039, Institut de Biologie Structurale et Microbiologie, CNRS, France.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
BARLEY ALPHA-AMYLASE 2(CV MENUET)
A, B
403Hordeum vulgareMutation(s): 0 
EC: 3.2.1.1
UniProt
Find proteins for P04063 (Hordeum vulgare)
Explore P04063 
Go to UniProtKB:  P04063
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP04063
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
BARLEY ALPHA-AMYLASE/SUBTILISIN INHIBITOR
C, D
181Hordeum vulgareMutation(s): 0 
UniProt
Find proteins for P07596 (Hordeum vulgare)
Explore P07596 
Go to UniProtKB:  P07596
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP07596
Sequence Annotations
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.208 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 74.5α = 90
b = 96.18β = 90
c = 170.15γ = 90
Software Package:
Software NamePurpose
XDSdata scaling
XSCALEdata scaling
X-PLORmodel building
X-PLORrefinement
XDSdata reduction
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-03-16
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-04-03
    Changes: Data collection, Database references, Derived calculations, Refinement description