1Y6I

Synechocystis GUN4


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.78 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.221 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Structure of the Mg-chelatase cofactor GUN4 reveals a novel hand-shaped fold for porphyrin binding

Verdecia, M.A.Larkin, R.M.Ferrer, J.L.Riek, R.Chory, J.Noel, J.P.

(2005) PLoS Biol 3: 151-151

  • DOI: 10.1371/journal.pbio.0030151
  • Primary Citation of Related Structures:  
    1Y6I

  • PubMed Abstract: 
  • In plants, the accumulation of the chlorophyll precursor Mg-protoporphyrin IX (Mg-Proto) in the plastid regulates the expression of a number of nuclear genes with functions related to photosynthesis. Analysis of the plastid-to-nucleus signaling activity of Mg-Proto in Arabidopsis thaliana led to the discovery of GUN4, a novel porphyrin-binding protein that also dramatically enhances the activity of Mg-chelatase, the enzyme that synthesizes Mg-Proto ...

    In plants, the accumulation of the chlorophyll precursor Mg-protoporphyrin IX (Mg-Proto) in the plastid regulates the expression of a number of nuclear genes with functions related to photosynthesis. Analysis of the plastid-to-nucleus signaling activity of Mg-Proto in Arabidopsis thaliana led to the discovery of GUN4, a novel porphyrin-binding protein that also dramatically enhances the activity of Mg-chelatase, the enzyme that synthesizes Mg-Proto. GUN4 may also play a role in both photoprotection and the cellular shuttling of tetrapyrroles. Here we report a 1.78-A resolution crystal structure of Synechocystis GUN4, in which the porphyrin-binding domain adopts a unique three dimensional fold with a "cupped hand" shape. Biophysical and biochemical analyses revealed the specific site of interaction between GUN4 and Mg-Proto and the energetic determinants for the GUN4.Mg-Proto interaction. Our data support a novel protective function for GUN4 in tetrapyrrole trafficking. The combined structural and energetic analyses presented herein form the physical-chemical basis for understanding GUN4 biological activity, including its role in the stimulation of Mg-chelatase activity, as well as in Mg-Proto retrograde signaling.


    Organizational Affiliation

    Chemical Biology and Proteomics Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Mg-chelatase cofactor GUN4A233Synechocystis sp. PCC 6803Mutation(s): 0 
Gene Names: gun4
UniProt
Find proteins for P72583 (Synechocystis sp. (strain PCC 6803 / Kazusa))
Explore P72583 
Go to UniProtKB:  P72583
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.78 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.221 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 63.907α = 90
b = 70.71β = 90
c = 72.645γ = 90
Software Package:
Software NamePurpose
CNSrefinement
HKL-2000data reduction
SCALEPACKdata scaling
SOLVEphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-05-31
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.3: 2017-10-11
    Changes: Data collection