Structure of the Chlamydomonas rheinhardtii Moco Carrier Protein

Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.184 
  • R-Value Observed: 0.186 

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This is version 1.2 of the entry. See complete history


Function and Structure of the Molybdenum Cofactor Carrier Protein from Chlamydomonas Reinhardtii.

Fischer, K.Llamas, A.Tejada-Jimenez, M.Schrader, N.Kuper, J.Ataya, F.S.Galvan, A.Mendel, R.R.Fernandez, E.Schwarz, G.

(2006) J Biol Chem 281: 30186

  • DOI: https://doi.org/10.1074/jbc.M603919200
  • Primary Citation of Related Structures:  
    2IZ5, 2IZ6, 2IZ7

  • PubMed Abstract: 

    The molybdenum cofactor (Moco) forms the catalytic site in all eukaryotic molybdenum enzymes and is synthesized by a multistep biosynthetic pathway. The mechanism of transfer, storage, and insertion of Moco into the appropriate apo-enzyme is poorly understood. In Chlamydomonas reinhardtii, a Moco carrier protein (MCP) has been identified and characterized recently. Here we show biochemical evidence that MCP binds Moco as well as the tungstate-substituted form of the cofactor (Wco) with high affinity, whereas molybdopterin, the ultimate cofactor precursor, is not bound. This binding selectivity points to a specific metal-mediated interaction with MCP, which protects Moco and Wco from oxidation with t((1/2)) of 24 and 96 h, respectively. UV-visible spectroscopy showed defined absorption bands at 393, 470, and 570 nm pointing to ene-diothiolate and protein side-chain charge transfer bonds with molybdenum. We have determined the crystal structure of MCP at 1.6 Angstrom resolution using seleno-methionated and native protein. The monomer constitutes a Rossmann fold with two homodimers forming a symmetrical tetramer in solution. Based on conserved surface residues, charge distribution, shape, in silico docking studies, structural comparisons, and identification of an anionbinding site, a prominent surface depression was proposed as a Moco-binding site, which was confirmed by structure-guided mutagenesis coupled to substrate binding studies.

  • Organizational Affiliation

    Institute of Plant Biology, Technical University Braunschweig, 38106 Braunschweig, Germany.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
176Chlamydomonas reinhardtiiMutation(s): 0 
Find proteins for Q8RV61 (Chlamydomonas reinhardtii)
Explore Q8RV61 
Go to UniProtKB:  Q8RV61
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8RV61
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.184 
  • R-Value Observed: 0.186 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 68.079α = 90
b = 126.009β = 90
c = 75.68γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-07-26
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Refinement description, Version format compliance
  • Version 1.2: 2023-12-13
    Changes: Data collection, Database references, Other, Refinement description