1ZDR

DHFR from Bacillus Stearothermophilus


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.210 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure and hydride transfer mechanism of a moderate thermophilic dihydrofolate reductase from Bacillus stearothermophilus and comparison to its mesophilic and hyperthermophilic homologues.

Kim, H.S.Damo, S.M.Lee, S.Y.Wemmer, D.Klinman, J.P.

(2005) Biochemistry 44: 11428-11439

  • DOI: 10.1021/bi050630j

  • PubMed Abstract: 
  • Dihydrofolate reductase (DHFR) from a moderate thermophilic organism, Bacillus stearothermophilus, has been cloned and expressed. Physical characterization of the protein (BsDHFR) indicates that it is a monomeric protein with a molecular mass of 18,6 ...

    Dihydrofolate reductase (DHFR) from a moderate thermophilic organism, Bacillus stearothermophilus, has been cloned and expressed. Physical characterization of the protein (BsDHFR) indicates that it is a monomeric protein with a molecular mass of 18,694.6 Da (0.8), coincident with the mass of 18 694.67 Da calculated from the primary sequence. Determination of the X-ray structure of BsDHFR provides the first structure for a monomeric DHFR from a thermophilic organism, indicating a high degree of conservation of structure in relation to all chromosomal DHFRs. Structurally based sequence alignment of DHFRs indicates the following levels of sequence identity and similarity for BsDHFR: 38 and 58% with Escherichia coli, 35 and 56% with Lactobacillus casei, and 23 and 40% with Thermotoga maritima, respectively. Steady state kinetic isotope effect studies indicate an ordered kinetic mechanism at elevated temperatures, with NADPH binding first to the enzyme. This converts to a more random mechanism at reduced temperatures, reflected in a greatly reduced K(m) for dihydrofolate at 20 degrees C in relation to that at 60 degrees C. A reduction in either temperature or pH reduces the degree to which the hydride transfer step is rate-determining for the second-order reaction of DHF with the enzyme-NADPH binary complex. Transient state kinetics have been used to study the temperature dependence of the isotope effect on hydride transfer at pH 9 between 10 and 50 degrees C. The data support rate-limiting hydride transfer with a moderate enthalpy of activation (E(a) = 5.5 kcal/mol) and a somewhat greater temperature dependence for the kinetic isotope effect than predicted from classical behavior [A(H)/A(D) = 0.57 (0.15)]. Comparison of kinetic parameters for BsDHFR to published data for DHFR from E. coli and T. maritima shows a decreasing trend in efficiency of hydride transfer with increasing thermophilicity of the protein. These results are discussed in the context of the capacity of each enzyme to optimize H-tunneling from donor (NADPH) to acceptor (DHF) substrates.


    Organizational Affiliation

    Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
dihydrofolate reductase
A, B
164Geobacillus kaustophilus (strain HTA426)EC: 1.5.1.3
Find proteins for Q5KZ26 (Geobacillus kaustophilus (strain HTA426))
Go to UniProtKB:  Q5KZ26
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

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A, B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
GOL
Query on GOL

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Download CCD File 
B
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.210 
  • Space Group: P 4 21 2
Unit Cell:
Length (Å)Angle (°)
a = 104.650α = 90.00
b = 104.650β = 90.00
c = 116.370γ = 90.00
Software Package:
Software NamePurpose
SCALEPACKdata scaling
DENZOdata reduction
MOLREPphasing
CNSrefinement
Omodel building

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-08-30
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Non-polymer description, Version format compliance