2BJI

High Resolution Structure of myo-Inositol Monophosphatase, The Target of Lithium Therapy


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.24 Å
  • R-Value Free: 0.191 

wwPDB Validation 3D Report Full Report


This is version 1.4 of the entry. See complete history

Literature

High-resolution structure of myo-inositol monophosphatase, the putative target of lithium therapy.

Gill, R.Mohammed, F.Badyal, R.Coates, L.Erskine, P.Thompson, D.Cooper, J.Gore, M.Wood, S.

(2005) Acta Crystallogr. D Biol. Crystallogr. 61: 545-555

  • DOI: 10.1107/S0907444905004038

  • PubMed Abstract: 
  • Inositol monophosphatase is a key enzyme of the phosphatidylinositol signalling pathway and the putative target of the mood-stabilizing drug lithium. The crystal structure of bovine inositol monophosphatase has been determined at 1.4 A resolution in ...

    Inositol monophosphatase is a key enzyme of the phosphatidylinositol signalling pathway and the putative target of the mood-stabilizing drug lithium. The crystal structure of bovine inositol monophosphatase has been determined at 1.4 A resolution in complex with the physiological magnesium ion ligands. Three magnesium ions are octahedrally coordinated at the active site of each of the two subunits of the inositol monophosphatase dimer and a detailed three-metal mechanism is proposed. Ligands to the three metals include the side chains of Glu70, Asp90, Asp93 and Asp220, the backbone carbonyl group of Ile92 and several solvent molecules, including the proposed nucleophilic water molecule (W1) ligated by both Mg-1 and Mg-3. Modelling of the phosphate moiety of inositol monophosphate to superpose the axial phosphate O atoms onto three active-site water molecules orientates the phosphoester bond for in-line attack by the nucleophilic water which is activated by Thr95. Modelling of the pentacoordinate transition state suggests that the 6-OH group of the inositol moiety stabilizes the developing negative charge by hydrogen bonding to a phosphate O atom. Modelling of the post-reaction complex suggests a role for a second water molecule (W2) ligated by Mg-2 and Asp220 in protonating the departing inositolate. This second water molecule is absent in related structures in which lithium is bound at site 2, providing a rationale for enzyme inhibition by this simple monovalent cation. The higher resolution structural information on the active site of inositol monophosphatase will facilitate the design of substrate-based inhibitors and aid in the development of better therapeutic agents for bipolar disorder (manic depression).


    Organizational Affiliation

    Biomolecular Sciences Group, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, England.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
INOSITOL-1(OR 4)-MONOPHOSPHATASE
A, B
277Bos taurusMutation(s): 0 
Gene Names: IMPA1 (IMPA)
EC: 3.1.3.25
Find proteins for P20456 (Bos taurus)
Go to Gene View: IMPA1
Go to UniProtKB:  P20456
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MG
Query on MG

Download SDF File 
Download CCD File 
A, B
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.24 Å
  • R-Value Free: 0.191 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 47.230α = 67.22
b = 55.150β = 69.65
c = 60.880γ = 85.14
Software Package:
Software NamePurpose
SCALAdata scaling
MOSFLMdata reduction
SHELXL-97refinement
AMoREphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-02-11
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2018-02-28
    Type: Advisory, Database references, Source and taxonomy
  • Version 1.4: 2019-05-08
    Type: Data collection, Experimental preparation