1O8O

The active site of the molybdenum cofactor biosynthetic protein domain Cnx1G


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.200 

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This is version 1.2 of the entry. See complete history


Literature

The Active Site of the Molybdenum Cofactor Biosynthetic Protein Domain Cnx1G

Kuper, J.Winking, J.Hecht, H.J.Mendel, R.R.Schwarz, G.

(2003) Arch Biochem Biophys 411: 36

  • DOI: 10.1016/s0003-9861(02)00714-2
  • Primary Citation of Related Structures:  
    1O8Q, 1O8O, 1O8N

  • PubMed Abstract: 
  • The final step of molybdenum cofactor biosynthesis in plants is catalyzed by the two-domain protein Cnx1. The G domain of Cnx1 (Cnx1G) binds molybdopterin with high affinity and transfers molybdenum to molybdopterin. Here, we describe the functional and structural characterization of structure-based Cnx1G mutants ...

    The final step of molybdenum cofactor biosynthesis in plants is catalyzed by the two-domain protein Cnx1. The G domain of Cnx1 (Cnx1G) binds molybdopterin with high affinity and transfers molybdenum to molybdopterin. Here, we describe the functional and structural characterization of structure-based Cnx1G mutants. For molybdopterin binding residues Thr542 and Ser573 were found to be important because different mutations of those residues resulted in 7- to 26-fold higher k(D) values for molybdopterin binding. Furthermore, we showed that the terminal phosphate of molybdopterin is directly involved in protein-pterin interactions as dephosphorylated molybdopterin binds with one magnitude of order lower affinity to the wild-type protein. Molybdopterin binding was not affected in mutants defective in Ser476, Asp486, or Asp515. However, molybdenum insertion was completely abolished, indicating their important role for catalysis. Based on these results we propose the binding of molybdopterin to a large depression in the structure of Cnx1G formed by beta5, alpha5, beta6, and alpha6, whereas the negatively charged depression formed by the loop between beta3 and alpha4, the N-terminal end of alpha2, the 3(10) helix, and the region between beta6 and alpha6 is involved in catalysis.


    Organizational Affiliation

    Department of Plant Biology, Technical University of Braunschweig, 38028, Braunschweig, Germany.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
MOLYBDOPTERIN BIOSYNTHESIS CNX1 PROTEINA, B, C167Arabidopsis thalianaMutation(s): 1 
Gene Names: CNX1At5g20990F22D1.6T10F18.20
EC: 2.10.1.1 (UniProt), 2.7.7.75 (UniProt)
UniProt
Find proteins for Q39054 (Arabidopsis thaliana)
Explore Q39054 
Go to UniProtKB:  Q39054
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.200 
  • Space Group: I 41 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 122.263α = 90
b = 122.263β = 90
c = 174.623γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
AMoREphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-12-04
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance