3GE3

Crystal Structure of the reduced Toluene 4-Monooxygenase HD T201A mutant complex


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.52 Å
  • R-Value Free: 0.193 
  • R-Value Work: 0.168 
  • R-Value Observed: 0.169 

Starting Model: experimental
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This is version 1.4 of the entry. See complete history


Literature

Role for threonine 201 in the catalytic cycle of the soluble diiron hydroxylase toluene 4-monooxygenase.

Elsen, N.L.Bailey, L.J.Hauser, A.D.Fox, B.G.

(2009) Biochemistry 48: 3838-3846

  • DOI: https://doi.org/10.1021/bi900144a
  • Primary Citation of Related Structures:  
    3GE3, 3GE8

  • PubMed Abstract: 

    The active site residue Thr-201 in toluene 4-monooxygenase hydroxylase (T4moH) has a structural counterpart in the active sites of all diiron monooxygenases. Thus, our previous finding that mutation of this residue to Ala, Gly, or Ser had no impact on steady-state catalysis or coupling was surprising. In this work, we provide kinetic, biochemical, and structural evidence that one role of Thr-201 may be to stabilize a peroxo-level intermediate during enzyme catalysis. During reactions in the absence of substrate, T201 T4moH slowly consumed O(2) but only a negligible amount of H(2)O(2) was released. In contrast, T201A T4moH gave stoichometric release of H(2)O(2) during reaction in the absence of substrate. Both enzyme isoforms were tightly coupled during steady-state catalysis with saturating toluene and other optimal substrates and exhibited near-identical kinetic parameters. However, rapid mix single-turnover studies showed that T201A T4moH had a faster first-order rate constant for product formation than T201 T4moH did. Comparison of X-ray crystal structures of resting and reduced T201A T4moH in complex with T4moD with comparable structures of T201 T4moHD revealed changes in the positions of several key active site residues relative to the comparable structures of T201 T4moH with T4moD. This combination of catalytic and structural studies offers important new insight into the role of the role of conserved Thr-201, and its contributions to the catalytic reaction cycle.


  • Organizational Affiliation

    Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin, Madison, Wisconsin 53706-1544, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Toluene-4-monooxygenase system protein A500Ectopseudomonas mendocinaMutation(s): 1 
Gene Names: tmoA
EC: 1.14.13 (PDB Primary Data), 1.14.13.236 (UniProt)
UniProt
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UniProt GroupQ00456
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Toluene-4-monooxygenase system protein E327Ectopseudomonas mendocinaMutation(s): 0 
Gene Names: tmoE
EC: 1.14.13 (PDB Primary Data), 1.14.13.236 (UniProt)
UniProt
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
Toluene-4-monooxygenase system protein B84Ectopseudomonas mendocinaMutation(s): 0 
Gene Names: tmoB
EC: 1.14.13 (PDB Primary Data), 1.14.13.236 (UniProt)
UniProt
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Entity ID: 4
MoleculeChains Sequence LengthOrganismDetailsImage
Toluene-4-monooxygenase system protein DD [auth E]103Ectopseudomonas mendocinaMutation(s): 0 
Gene Names: tmoD
EC: 1.14.13
UniProt
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.52 Å
  • R-Value Free: 0.193 
  • R-Value Work: 0.168 
  • R-Value Observed: 0.169 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 100.26α = 90
b = 115.966β = 90
c = 180.137γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
MOLREPphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-07-28
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2014-07-02
    Changes: Structure summary
  • Version 1.3: 2021-10-20
    Changes: Database references, Derived calculations
  • Version 1.4: 2023-09-06
    Changes: Data collection, Refinement description