1H9J

Two crystal structures of the cytoplasmic molybdate-binding protein ModG suggest a novel cooperative binding mechanism and provide insights into ligand-binding specificity. Phosphate-grown form with molybdate and phosphate bound


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.200 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Two Crystal Structures of the Cytoplasmic Molybdate-Binding Protein Modg Suggest a Novel Cooperative Binding Mechanism and Provide Insights Into Ligand-Binding Specificity

Delarbre, L.Stevenson, C.E.M.White, D.J.Mitchenall, L.A.Pau, R.N.Lawson, D.M.

(2001) J.Mol.Biol. 308: 1063

  • DOI: 10.1006/jmbi.2001.4636
  • Primary Citation of Related Structures:  1H9K, 1H9M

  • PubMed Abstract: 
  • The X-ray structures of the cytoplasmic molybdate-binding protein ModG from Azotobacter vinelandii in two different crystal forms have been determined. For such a small protein it is remarkably complex. Each 14.3 kDa subunit contains two small beta-b ...

    The X-ray structures of the cytoplasmic molybdate-binding protein ModG from Azotobacter vinelandii in two different crystal forms have been determined. For such a small protein it is remarkably complex. Each 14.3 kDa subunit contains two small beta-barrel domains, which display an OB-fold motif, also seen in the related structure of ModE, a molybdenum-dependent transcriptional regulator, and very recently in the Mop protein that, like ModG, has been implicated in molybdenum homeostasis within the cell. In contrast to earlier speculation, the functional unit of ModG is actually not a dimer (as in ModE), but a trimer capable of binding a total of eight molybdate molecules that are distributed between two disparate types of site. All the binding sites are located at subunit interfaces, with one type lying on a crystallographic 3-fold axis, whilst the other lies between pairs of subunits. The two types of site are linked by short hydrogen bond networks that may suggest a cooperative binding mechanism. A superposition of two subunits of the ModG trimer on the apo-ModE dimer allows the probable locations of the molybdate-binding sites of the latter to be assigned. Through structural comparisons with other oxyanion-binding proteins, including Mop and ModE, it is possible to speculate about ligand-binding affinities, selectivity and evolution.


    Organizational Affiliation

    Department of Biological Chemistry, Norwich, NR4 7UH, UK.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
MOLYBDENUM-BINDING-PROTEIN
A
145Azotobacter vinelandiiGene Names: modG
Find proteins for Q44529 (Azotobacter vinelandii)
Go to UniProtKB:  Q44529
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

Download SDF File 
Download CCD File 
A
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
MOO
Query on MOO

Download SDF File 
Download CCD File 
A
MOLYBDATE ION
MOLYBDATE
Mo O4
MEFBJEMVZONFCJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.200 
  • Space Group: P 3 2 1
Unit Cell:
Length (Å)Angle (°)
a = 50.685α = 90.00
b = 50.685β = 90.00
c = 79.112γ = 120.00
Software Package:
Software NamePurpose
REFMACrefinement
SCALEPACKdata scaling
DENZOdata reduction
MLPHAREphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-05-11
    Type: Initial release
  • Version 1.1: 2011-05-07
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance