2Z51

Crystal structure of Arabidopsis CnfU involved in iron-sulfur cluster biosynthesis

Summary for 2Z51

• Entry DOI: 10.2210/pdb2z51/pdb
• Descriptor: NifU-like protein 2, chloroplast, MAGNESIUM ION (3 entities in total)
• Functional Keywords: cnfu, iron-sulfur cluster biosynthesis, nif, metal transport
• Biological source: Arabidopsis thaliana (Mouse-ear cress)
• Total number of polymer chains: 1
• Total formula weight: 16871.10

Authors

Yabe, T.,Yamashita, E.,Nakai, M. (deposition date: 2007-06-26, release date: 2008-07-15, Last modification date: 2024-03-13)

Primary citation

Yabe, T.,Yamashita, E.,Kikuchi, A.,Morimoto, K.,Nakagawa, A.,Tsukihara, T.,Nakai, M.
Structural Analysis of Arabidopsis CnfU Protein: An Iron-Sulfur Cluster Biosynthetic Scaffold in Chloroplasts.
J.Mol.Biol., 2008

PubMed Abstract: CnfU, a key iron-sulfur (Fe-S) cluster biosynthetic scaffold that is required for biogenesis of ferredoxin and photosystem I in chloroplasts, consists of two tandemly repeated domains in which only the N-terminal domain contains a conserved CXXC motif. We have determined the crystal structure of the metal-free dimer of AtCnfU-V from Arabidopsis thaliana at 1.35 A resolution. The N-terminal domains of the two monomers are linked together through two intermolecular disulfide bonds between the CXXC motifs. At the dimer interface, a total of four cysteine sulfur atoms provide a Fe-S cluster assembly site surrounded by uncharged but hydrophilic structurally mobile segments. The C-terminal domain of one monomer interacts with the N-terminal domain of the opposing monomer and thereby stabilizes dimer formation. Furthermore, Fe K-edge X-ray absorption spectroscopic analysis of the holo-CnfU dimer in solution suggests the presence of a typical [2Fe-2S]-type cluster coordinated by four thiolate ligands. Based on these data, a plausible model of the holo-AtCnfU-V dimer containing a surface-exposed [2Fe-2S] cluster assembled in the dimer interface was deduced. We propose that such a structural framework is important for CnfU to function as a Fe-S cluster biosynthetic scaffold.

PubMed: 18585737
DOI: 10.1016/j.jmb.2008.05.072

Experimental method

X-RAY DIFFRACTION (1.35 Å)