1KW0

Catalytic Domain of Human Phenylalanine Hydroxylase (Fe(II)) in Complex with Tetrahydrobiopterin and Thienylalanine


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.267 
  • R-Value Work: 0.220 

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This is version 1.3 of the entry. See complete history


Literature

Crystal Structure of the Ternary Complex of the Catalytic Domain of Human Phenylalanine Hydroxylase with Tetrahydrobiopterin and 3-(2-thienyl)-L-alanine, and its Implications for the Mechanism of Catalysis and Substrate Activation

Andersen, O.A.Flatmark, T.Hough, E.

(2002) J Mol Biol 320: 1095-1108

  • DOI: 10.1016/s0022-2836(02)00560-0
  • Primary Citation of Related Structures:  
    1KW0

  • PubMed Abstract: 
  • Phenylalanine hydroxylase catalyzes the stereospecific hydroxylation of L-phenylalanine, the committed step in the degradation of this amino acid. We have solved the crystal structure of the ternary complex (hPheOH-Fe(II).BH(4).THA) of the catalytically active Fe(II) form of a truncated form (DeltaN1-102/DeltaC428-452) of human phenylalanine hydroxylase (hPheOH), using the catalytically active reduced cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)) and 3-(2-thienyl)-L-alanine (THA) as a substrate analogue ...

    Phenylalanine hydroxylase catalyzes the stereospecific hydroxylation of L-phenylalanine, the committed step in the degradation of this amino acid. We have solved the crystal structure of the ternary complex (hPheOH-Fe(II).BH(4).THA) of the catalytically active Fe(II) form of a truncated form (DeltaN1-102/DeltaC428-452) of human phenylalanine hydroxylase (hPheOH), using the catalytically active reduced cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)) and 3-(2-thienyl)-L-alanine (THA) as a substrate analogue. The analogue is bound in the second coordination sphere of the catalytic iron atom with the thiophene ring stacking against the imidazole group of His285 (average interplanar distance 3.8A) and with a network of hydrogen bonds and hydrophobic contacts. Binding of the analogue to the binary complex hPheOH-Fe(II).BH(4) triggers structural changes throughout the entire molecule, which adopts a slightly more compact structure. The largest change occurs in the loop region comprising residues 131-155, where the maximum r.m.s. displacement (9.6A) is at Tyr138. This loop is refolded, bringing the hydroxyl oxygen atom of Tyr138 18.5A closer to the iron atom and into the active site. The iron geometry is highly distorted square pyramidal, and Glu330 adopts a conformation different from that observed in the hPheOH-Fe(II).BH(4) structure, with bidentate iron coordination. BH(4) binds in the second coordination sphere of the catalytic iron atom, and is displaced 2.6A in the direction of Glu286 and the iron atom, relative to the hPheOH-Fe(II).BH(4) structure, thus changing its hydrogen bonding network. The active-site structure of the ternary complex gives new insight into the substrate specificity of the enzyme, notably the low affinity for L-tyrosine. Furthermore, the structure has implications both for the catalytic mechanism and the molecular basis for the activation of the full-length tetrameric enzyme by its substrate. The large conformational change, moving Tyr138 from a surface position into the active site, may reflect a possible functional role for this residue.


    Organizational Affiliation

    Department of Chemistry, University of Tromsø, N-9037, Tromso, Norway.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Phenylalanine-4-hydroxylase A325Homo sapiensMutation(s): 0 
Gene Names: PAH
EC: 1.14.16.1
Find proteins for P00439 (Homo sapiens)
Explore P00439 
Go to UniProtKB:  P00439
NIH Common Fund Data Resources
PHAROS:  P00439
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
H4B
Query on H4B

Download Ideal Coordinates CCD File 
A
5,6,7,8-TETRAHYDROBIOPTERIN
C9 H15 N5 O3
FNKQXYHWGSIFBK-RPDRRWSUSA-N
 Ligand Interaction
TIH
Query on TIH

Download Ideal Coordinates CCD File 
A
BETA(2-THIENYL)ALANINE
C7 H9 N O2 S
WTOFYLAWDLQMBZ-LURJTMIESA-N
 Ligand Interaction
FE2
Query on FE2

Download Ideal Coordinates CCD File 
A
FE (II) ION
Fe
CWYNVVGOOAEACU-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.267 
  • R-Value Work: 0.220 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 65.172α = 90
b = 106.741β = 90
c = 123.44γ = 90
Software Package:
Software NamePurpose
MAR345data collection
SCALAdata scaling
CNSrefinement
CCP4data scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-01-28
    Type: Initial release
  • Version 1.1: 2007-10-16
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-10-11
    Changes: Refinement description