1y6i
From Proteopedia
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Synechocystis GUN4
Overview
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.
About this Structure
1Y6I is a Single protein structure of sequence from Synechocystis sp.. Full crystallographic information is available from OCA.
Reference
Structure of the Mg-chelatase cofactor GUN4 reveals a novel hand-shaped fold for porphyrin binding., Verdecia MA, Larkin RM, Ferrer JL, Riek R, Chory J, Noel JP, PLoS Biol. 2005 May;3(5):e151. Epub 2005 Apr 26. PMID:15884974
Page seeded by OCA on Wed Nov 21 06:36:16 2007
