2GA3

Structure of S102T E. coli Alkaline Phosphatase-phosphate intermediate at 2.20A resolution


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.192 
  • R-Value Observed: 0.192 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Trapping the tetrahedral intermediate in the alkaline phosphatase reaction by substitution of the active site serine with threonine.

Wang, J.Kantrowitz, E.R.

(2006) Protein Sci 15: 2395-2401

  • DOI: 10.1110/ps.062351506
  • Primary Citation of Related Structures:  
    2G9Y, 2GA3

  • PubMed Abstract: 
  • We report here the construction of a mutant version of Escherichia coli alkaline phosphatase (AP) in which the active site Ser was replaced by Thr (S102T), in order to investigate whether the enzyme can utilize Thr as the nucleophile and whether the ...

    We report here the construction of a mutant version of Escherichia coli alkaline phosphatase (AP) in which the active site Ser was replaced by Thr (S102T), in order to investigate whether the enzyme can utilize Thr as the nucleophile and whether the rates of the critical steps in the mechanism are altered by the substitution. The mutant AP with Thr at position 102 exhibited an approximately 4000-fold decrease in k(cat) along with a small decrease in Km. The decrease in catalytic efficiency of approximately 2000-fold was a much smaller drop than that observed when Ala or Gly were substituted at position 102. The mechanism by which Thr can substitute for Ser in AP was further investigated by determining the X-ray structure of the S102T enzyme in the presence of the Pi (S102T_Pi), and after soaking the crystals with substrate (S102T_sub). In the S102T_Pi structure, the Pi was coordinated differently with its position shifted by 1.3 A compared to the structure of the wild-type enzyme in the presence of Pi. In the S102T_sub structure, a covalent Thr-Pi intermediate was observed, instead of the expected bound substrate. The stereochemistry of the phosphorus in the S102T_sub structure was inverted compared to the stereochemistry in the wild-type structure, as would be expected after the first step of a double in-line displacement mechanism. We conclude that the S102T mutation resulted in a shift in the rate-determining step in the mechanism allowing us to trap the covalent intermediate of the reaction in the crystal.


    Organizational Affiliation

    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Alkaline phosphataseAB449Escherichia coliMutation(s): 1 
Gene Names: phoA
EC: 3.1.3.1
Find proteins for P00634 (Escherichia coli (strain K12))
Explore P00634 
Go to UniProtKB:  P00634
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download CCD File 
A, B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
ZN
Query on ZN

Download CCD File 
A, B
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
MG
Query on MG

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A, B
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
TPO
Query on TPO
A,BL-PEPTIDE LINKINGC4 H10 N O6 PTHR
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.192 
  • R-Value Observed: 0.192 
  • Space Group: I 2 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 76.23α = 90
b = 164.97β = 90
c = 192.9γ = 90
Software Package:
Software NamePurpose
CNSrefinement
d*TREKdata reduction
d*TREKdata scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-10-10
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-10-18
    Changes: Refinement description