1Q0N

CRYSTAL STRUCTURE OF A TERNARY COMPLEX OF 6-HYDROXYMETHYL-7,8-DIHYDROPTERIN PYROPHOSPHOKINASE FROM E. COLI WITH MGAMPCPP AND 6-HYDROXYMETHYL-7,8-DIHYDROPTERIN AT 1.25 ANGSTROM RESOLUTION


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.25 Å
  • R-Value Free: 0.147 
  • R-Value Work: 0.101 
  • R-Value Observed: 0.096 

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


Literature

Catalytic Center Assembly of Hppk as Revealed by the Crystal Structure of a Ternary Complex at 1.25 A Resolution

Blaszczyk, J.Shi, G.Yan, H.Ji, X.

(2000) Structure 8: 1049-1058

  • DOI: https://doi.org/10.1016/s0969-2126(00)00502-5
  • Primary Citation of Related Structures:  
    1Q0N

  • PubMed Abstract: 

    Folates are essential for life. Unlike mammals, most microorganisms must synthesize folates de novo. 6-Hydroxymethyl-7, 8-dihydropterin pyrophosphokinase (HPPK) catalyzes pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in the folate pathway, and therefore is an ideal target for developing novel antimicrobial agents. HPPK from Escherichia coli is a 158-residue thermostable protein that provides a convenient model system for mechanistic studies. Crystal structures have been reported for HPPK without bound ligand, containing an HP analog, and complexed with an HP analog, two Mg(2+) ions, and ATP. We present the 1.25 A crystal structure of HPPK in complex with HP, two Mg(2+) ions, and AMPCPP (an ATP analog that inhibits the enzymatic reaction). This structure demonstrates that the enzyme seals the active center where the reaction occurs. The comparison with unligated HPPK reveals dramatic conformational changes of three flexible loops and many sidechains. The coordination of Mg(2+) ions has been defined and the roles of 26 residues have been derived. HPPK-HP-MgAMPCPP mimics most closely the natural ternary complex of HPPK and provides details of protein-substrate interactions. The coordination of the two Mg(2+) ions helps create the correct geometry for the one-step reaction of pyrophosphoryl transfer, for which we suggest an in-line single displacement mechanism with some associative character in the transition state. The rigidity of the adenine-binding pocket and hydrogen bonds are responsible for adenosine specificity. The nonconserved residues that interact with the substrate might be responsible for the species-dependent properties of an isozyme.


  • Organizational Affiliation

    Program in Structural Biology National Cancer Institute-Frederick Cancer Research and Development Center 21702, Frederick, MD 21702, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase158Escherichia coliMutation(s): 0 
Gene Names: FOLK OR B0142
EC: 2.7.6.3
UniProt
Find proteins for P26281 (Escherichia coli (strain K12))
Explore P26281 
Go to UniProtKB:  P26281
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP26281
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 5 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
APC
Query on APC

Download Ideal Coordinates CCD File 
I [auth A]DIPHOSPHOMETHYLPHOSPHONIC ACID ADENOSYL ESTER
C11 H18 N5 O12 P3
CAWZRIXWFRFUQB-IOSLPCCCSA-N
PH2
Query on PH2

Download Ideal Coordinates CCD File 
J [auth A]2-AMINO-6-HYDROXYMETHYL-7,8-DIHYDRO-3H-PTERIDIN-4-ONE
C7 H9 N5 O2
CQQNNQTXUGLUEV-UHFFFAOYSA-N
ACT
Query on ACT

Download Ideal Coordinates CCD File 
E [auth A],
F [auth A],
G [auth A],
H [auth A]
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
CL
Query on CL

Download Ideal Coordinates CCD File 
D [auth A]CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
MG
Query on MG

Download Ideal Coordinates CCD File 
B [auth A],
C [auth A]
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.25 Å
  • R-Value Free: 0.147 
  • R-Value Work: 0.101 
  • R-Value Observed: 0.096 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 73.591α = 90
b = 37.743β = 116.94
c = 57.909γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
AMoREphasing
SHELXL-97refinement

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-08-26
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2023-08-16
    Changes: Data collection, Database references, Derived calculations, Refinement description
  • Version 1.4: 2023-08-30
    Changes: Database references, Structure summary