1B1Y

SEVENFOLD MUTANT OF BARLEY BETA-AMYLASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.187 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The crystal structure of the sevenfold mutant of barley beta-amylase with increased thermostability at 2.5 A resolution.

Mikami, B.Yoon, H.J.Yoshigi, N.

(1999) J.Mol.Biol. 285: 1235-1243

  • DOI: 10.1006/jmbi.1998.2379

  • PubMed Abstract: 
  • The three-dimensional structure of the sevenfold mutant of barley beta-amylase (BBA-7s) with increased thermostability was determined by X-ray crystallography. The enzyme was purified as a single component and crystallized by a hanging drop method in ...

    The three-dimensional structure of the sevenfold mutant of barley beta-amylase (BBA-7s) with increased thermostability was determined by X-ray crystallography. The enzyme was purified as a single component and crystallized by a hanging drop method in the presence of 14 % PEG 6000. The crystals belong to space group P43212 with cell dimensions a=b=72.11 A, c=250.51 A. The diffraction data up to 2.5 A were collected after soaking the crystal in 100 mM maltose with Rsym of 8.6 %. The structure was determined by a molecular replacement method using soybean beta-amylase (SBA) as a search model and refined to an R-factor of 18.7 %. The final model included 500 amino acid residues, 141 water molecules and three glucose residues, which were located at subsites 1-2 and 4 in the active site. The r.m.s. distance of 485 Calpha atoms between BBA-7s and SBA was 0.62 A. Out of the seven mutated amino acids, four (Ser295Ala, Ile297Val, Ser351Pro and Ala376Ser) were substitutions from the common residues with SBA to the thermostable forms. A comparison of the structures of BBA-7s and SBA indicated that the side-chain of Ser376 makes new hydrogen bonds to the main-chain of an adjacent beta-strand, and that the side-chains of Val297 reduce an unfavorable interaction between the side-chains of Ala314. The mutation of Ser295Ala breaks the hydrogen bond between Ser295 OG and Tyr195 OH, which seems to be the reason for the unoccupied glucose residue at subsite 3. The tandem mutations at 350-352 including substitutions to two Pro residues suggested the reduction of main-chain entropy in the unfolded structure of this solvent-exposed protruded loop.


    Related Citations: 
    • Construction of a Plasmid Used for the Expression of a Sevenfold-Mutant Barley Beta-Amylase with Increased Thermostability in Escherichia Coli and Properties of the Sevenfold-Mutant Beta-Amylase
      Yoshigi, N.,Okada, Y.,Maeba, H.,Sahara, H.,Tamaki, T.
      (1995) J.Biochem.(Tokyo) 118: 562


    Organizational Affiliation

    Kyoto University, Uji, Kyoto, 611, Japan. mikami@soya.food.kyoto-u.ac.jp




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
PROTEIN (BETA-AMYLASE)
A
500Hordeum vulgareGene Names: BMY1 (AMYB)
EC: 3.2.1.2
Find proteins for P16098 (Hordeum vulgare)
Go to UniProtKB:  P16098
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
BGC
Query on BGC

Download SDF File 
Download CCD File 
A
BETA-D-GLUCOSE
C6 H12 O6
WQZGKKKJIJFFOK-VFUOTHLCSA-N
 Ligand Interaction
GLC
Query on GLC

Download SDF File 
Download CCD File 
A
ALPHA-D-GLUCOSE
C6 H12 O6
WQZGKKKJIJFFOK-DVKNGEFBSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.187 
  • Space Group: P 43 21 2
Unit Cell:
Length (Å)Angle (°)
a = 72.110α = 90.00
b = 72.110β = 90.00
c = 250.510γ = 90.00
Software Package:
Software NamePurpose
X-PLORrefinement
X-PLORphasing
SAINTdata reduction
SAINTdata scaling
X-PLORmodel building

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1998-12-02
    Type: Initial release
  • Version 1.1: 2007-10-16
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance