1PEZ

Bacillus circulans strain 251 mutant A230V


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.32 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.155 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Conversion of Cyclodextrin Glycosyltransferase into a Starch Hydrolase by Directed Evolution: The Role of Alanine 230 in Acceptor Subsite +1

Leemhuis, H.Rozeboom, H.J.Wilbrink, M.Euverink, G.J.Dijkstra, B.W.Dijkhuizen, L.

(2003) Biochemistry 42: 7518-7526

  • DOI: 10.1021/bi034439q

  • PubMed Abstract: 
  • Cyclodextrin glycosyltransferase (CGTase) preferably catalyzes transglycosylation reactions, whereas many other alpha-amylase family enzymes are hydrolases. Despite the availability of three-dimensional structures of several transglycosylases and hyd ...

    Cyclodextrin glycosyltransferase (CGTase) preferably catalyzes transglycosylation reactions, whereas many other alpha-amylase family enzymes are hydrolases. Despite the availability of three-dimensional structures of several transglycosylases and hydrolases of this family, the factors that determine the hydrolysis and transglycosylation specificity are far from understood. To identify the amino acid residues that are critical for the transglycosylation reaction specificity, we carried out error-prone PCR mutagenesis and screened for Bacillus circulans strain 251 CGTase mutants with increased hydrolytic activity. After three rounds of mutagenesis the hydrolytic activity had increased 90-fold, reaching the highest hydrolytic activity ever reported for a CGTase. The single mutation with the largest effect (A230V) occurred in a residue not studied before. The structure of this A230V mutant suggests that the larger valine side chain hinders substrate binding at acceptor subsite +1, although not to the extent that catalysis is impossible. The much higher hydrolytic than transglycosylation activity of this mutant indicates that the use of sugar acceptors is hindered especially. This observation is in favor of a proposed induced-fit mechanism, in which sugar acceptor binding at acceptor subsite +1 activates the enzyme in transglycosylation [Uitdehaag et al. (2000) Biochemistry 39, 7772-7780]. As the A230V mutation introduces steric hindrance at subsite +1, this mutation is expected to negatively affect the use of sugar acceptors. Thus, the characteristics of mutant A230V strongly support the existence of the proposed induced-fit mechanism in which sugar acceptor binding activates CGTase in a transglycosylation reaction.


    Organizational Affiliation

    Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Cyclomaltodextrin glucanotransferase
A
686Bacillus circulansGene Names: cgt
EC: 2.4.1.19
Find proteins for P43379 (Bacillus circulans)
Go to UniProtKB:  P43379
Small Molecules
Ligands 7 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
EPE
Query on EPE

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A
4-(2-HYDROXYETHYL)-1-PIPERAZINE ETHANESULFONIC ACID
HEPES
C8 H18 N2 O4 S
JKMHFZQWWAIEOD-UHFFFAOYSA-N
 Ligand Interaction
MAL
Query on MAL

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A
MALTOSE
C12 H22 O11
GUBGYTABKSRVRQ-ASMJPISFSA-N
 Ligand Interaction
CA
Query on CA

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A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
BGC
Query on BGC

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

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A
ALPHA-D-GLUCOSE
C6 H12 O6
WQZGKKKJIJFFOK-DVKNGEFBSA-N
 Ligand Interaction
ACY
Query on ACY

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A
ACETIC ACID
C2 H4 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-N
 Ligand Interaction
MPD
Query on MPD

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A
(4S)-2-METHYL-2,4-PENTANEDIOL
C6 H14 O2
SVTBMSDMJJWYQN-YFKPBYRVSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.32 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.155 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 117.622α = 90.00
b = 109.706β = 90.00
c = 65.577γ = 90.00
Software Package:
Software NamePurpose
DENZOdata reduction
CNSphasing
CNSrefinement
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-10-28
    Type: Initial release
  • Version 1.1: 2008-04-29
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance