Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Ligand Interaction

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors and generated by PQS (software)

Macromolecule Content

• Total Structure Weight: 60.32 kDa 
• Atom Count: 4706 
• Modelled Residue Count: 550 
• Deposited Residue Count: 554 
• Unique protein chains: 1

2BJI

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

• PDB DOI: 10.2210/pdb2BJI/pdb

• Classification: HYDROLASE
• Organism(s): Bos taurus
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2005-02-03 Released: 2005-02-11 
• Deposition Author(s): Gill, R., Mohammed, F., Badyal, R., Coates, L., Erskine, P., Thompson, D., Cooper, J., Gore, M., Wood, S.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.24 Å
• R-Value Free: 0.191 
• R-Value Observed: 0.153 

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

• PubMed: 15858264 
• DOI: 10.1107/S0907444905004038
• Primary Citation of Related Structures:  
  2BJI


• 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 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).

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Organizational Affiliation: 

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

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
INOSITOL-1(OR 4)-MONOPHOSPHATASE	A, B	277	Bos taurus	Mutation(s): 0  Gene Names: IMPA1, IMPA EC: 3.1.3.25 (PDB Primary Data), 3.1.3.94 (UniProt)
UniProt
Find proteins for P20456 (Bos taurus) Explore P20456  Go to UniProtKB:  P20456

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
MG	C [auth A], D [auth A], E [auth A], F [auth B], G [auth B], H [auth B]	MAGNESIUM ION Mg JLVVSXFLKOJNIY-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.24 Å
• R-Value Free: 0.191 
• R-Value Observed: 0.153 
• Space Group: P 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 47.23	α = 67.22
b = 55.15	β = 69.65
c = 60.88	γ = 85.14

Software Package:

Software Name	Purpose
SHELXL-97	refinement
MOSFLM	data reduction
SCALA	data scaling
AMoRE	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2005-02-03 
• Released Date: 2005-02-11 
Deposition Author(s): Gill, R., Mohammed, F., Badyal, R., Coates, L., Erskine, P., Thompson, D., Cooper, J., Gore, M., Wood, S.

Revision History  

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