1HDE

HALOALKANE DEHALOGENASE MUTANT WITH PHE 172 REPLACED WITH TRP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.7 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.205 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Kinetic characterization and X-ray structure of a mutant of haloalkane dehalogenase with higher catalytic activity and modified substrate range.

Schanstra, J.P.Ridder, I.S.Heimeriks, G.J.Rink, R.Poelarends, G.J.Kalk, K.H.Dijkstra, B.W.Janssen, D.B.

(1996) Biochemistry 35: 13186-13195

  • DOI: 10.1021/bi961151a

  • PubMed Abstract: 
  • Conversion of halogenated aliphatics by haloalkane dehalogenase proceeds via the formation of a covalent alkyl-enzyme intermediate which is subsequently hydrolyzed by water. In the wild type enzyme, the slowest step for both 1,2-dichloroethane and 1, ...

    Conversion of halogenated aliphatics by haloalkane dehalogenase proceeds via the formation of a covalent alkyl-enzyme intermediate which is subsequently hydrolyzed by water. In the wild type enzyme, the slowest step for both 1,2-dichloroethane and 1,2-dibromoethane conversion is a unimolecular enzyme isomerization preceding rapid halide dissociation. Phenylalanine 172 is located in a helix-loop-helix structure that covers the active site cavity of the enzyme, interacts with the C1 beta of 1,2-dichloroethane during catalysis, and could be involved in stabilization of this helix-loop-helix region of the cap domain of the enzyme. To obtain more information about the role of this residue in dehalogenase function, we performed a mutational analysis of position 172 and studied the kinetics and X-ray structure of the Phe172Trp enzyme. The Phe172Trp mutant had a 10-fold higher Kcat/Km for 1-chlorohexane and a 2-fold higher Kcat for 1,2-dibromoethane than the wild-type enzyme. The X-ray structure of the Phe172Trp enzyme showed a local conformational change in the helix-loop-helix region that covers the active site. This could explain the elevated activity for 1-chlorohexane of the Phe172Trp enzyme, since it allows this large substrate to bind more easily in the active site cavity. Pre-steady-state kinetic analysis showed that the increase in Kcat found for 1,2-dibromoethane conversion could be attributed to an increase in the rate of an enzyme isomerization step that preceeds halide release. The observed conformational difference between the helix-loop-helix structures of the wild-type enzyme and the faster mutant suggests that the isomerization required for halide release could be a conformational change that takes place in this region of the cap domain of the dehalogenase. It is proposed that Phe172 is involved in stabilization of the helix-loop-helix structure that covers the active site of the enzyme and creates a rigid hydrophobic cavity for small apolar halogenated alkanes.


    Related Citations: 
    • Refined X-Ray Structures of Haloalkane Dehalogenase at Ph 6.2 And Ph 8.2 And Implications for the Reaction Mechanism
      Verschueren, K.H.,Franken, S.M.,Rozeboom, H.J.,Kalk, K.H.,Dijkstra, B.W.
      (1993) J.Mol.Biol. 232: 856
    • Crystal Structure of Haloalkane Dehalogenase: An Enzyme to Detoxify Halogenated Alkanes
      Franken, S.M.,Rozeboom, H.J.,Kalk, K.H.,Dijkstra, B.W.
      (1991) Embo J. 10: 1297
    • Crystallization of Haloalkane Dehalogenase from Xanthobacter Autotrophicus Gj10
      Rozeboom, H.J.,Kingma, J.,Janssen, D.B.,Dijkstra, B.W.
      (1988) J.Mol.Biol. 200: 611
    • Crystallographic Analysis of the Catalytic Mechanism of Haloalkane Dehalogenase
      Verschueren, K.H.,Seljee, F.,Rozeboom, H.J.,Kalk, K.H.,Dijkstra, B.W.
      (1993) Nature 363: 693


    Organizational Affiliation

    Laboratory of Biochemistry, BIOSON Research Institute, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
HALOALKANE DEHALOGENASE
A, B
310Xanthobacter autotrophicusGene Names: dhlA
EC: 3.8.1.5
Find proteins for P22643 (Xanthobacter autotrophicus)
Go to UniProtKB:  P22643
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.7 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.205 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 95.680α = 90.00
b = 73.530β = 91.32
c = 41.600γ = 90.00
Software Package:
Software NamePurpose
X-PLORphasing
X-PLORmodel building
MADNESdata reduction
X-PLORrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1997-02-12
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance