1Y6I
Synechocystis GUN4
Summary for 1Y6I
| Entry DOI | 10.2210/pdb1y6i/pdb |
| Descriptor | Mg-chelatase cofactor GUN4 (2 entities in total) |
| Functional Keywords | helix-bundle, porphyrin binding, ligand binding protein |
| Biological source | Synechocystis sp. |
| Total number of polymer chains | 1 |
| Total formula weight | 26490.91 |
| Authors | Verdecia, M.A.,Larkin, R.M.,Ferrer, J.L.,Riek, R.,Chory, J.,Noel, J.P. (deposition date: 2004-12-06, release date: 2005-05-31, Last modification date: 2024-02-14) |
| Primary citation | Verdecia, M.A.,Larkin, R.M.,Ferrer, J.L.,Riek, R.,Chory, J.,Noel, J.P. Structure of the Mg-chelatase cofactor GUN4 reveals a novel hand-shaped fold for porphyrin binding Plos Biol., 3:151-151, 2005 Cited by 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. 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. PubMed: 15884974DOI: 10.1371/journal.pbio.0030151 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.78 Å) |
Structure validation
Download full validation report
