3EUN

Crystal structure of the 2[4Fe-4S] C57A ferredoxin variant from allochromatium vinosum

Summary for 3EUN

• Entry DOI: 10.2210/pdb3eun/pdb
• Related: 1BLU 2FDN 2FGO 3EXY
• Descriptor: Ferredoxin, IRON/SULFUR CLUSTER (3 entities in total)
• Functional Keywords: electron transport, ferredoxin, [4fe-4s] cluster, 4fe-4s, iron, iron-sulfur, metal-binding, transport
• Biological source: Allochromatium vinosum (Allochromatium vinosum)
• Total number of polymer chains: 1
• Total formula weight: 9735.22

Authors

Saridakis, E.,Mavridis, I.M. (deposition date: 2008-10-10, release date: 2009-08-18, Last modification date: 2023-09-06)

Primary citation

Saridakis, E.,Giastas, P.,Efthymiou, G.,Thoma, V.,Moulis, J.M.,Kyritsis, P.,Mavridis, I.M.
Insight into the protein and solvent contributions to the reduction potentials of [4Fe-4S]2+/+ clusters: crystal structures of the Allochromatium vinosum ferredoxin variants C57A and V13G and the homologous Escherichia coli ferredoxin.
J.Biol.Inorg.Chem., 14:783-799, 2009

PubMed Abstract: The crystal structures of the C57A and V13G molecular variants of Allochromatium vinosum 2[4Fe-4S] ferredoxin (AlvinFd) and that of the homologous ferredoxin from Escherichia coli (EcFd) have been determined at 1.05-, 1.48-, and 1.65-A resolution, respectively. The present structures combined with cyclic voltammetry studies establish clear effects of the degree of exposure of the cluster with the lowest reduction potential (cluster I) towards less negative reduction potentials (E degrees ). This is better illustrated by V13G AlvinFd (high exposure, E degrees = -594 mV) and EcFd (low exposure, E degrees = -675 mV). In C57A AlvinFd, the movement of the protein backbone, as a result of replacing the noncoordinating Cys57 by Ala, leads to a +50-mV upshift of the potential of the nearby cluster I, by removal of polar interactions involving the thiolate group and adjustment of the hydrogen-bond network involving the cluster atoms. In addition, the present structures and other previously reported accurate structures of this family of ferredoxins indicate that polar interactions of side chains and water molecules with cluster II sulfur atoms, which are absent in the environment of cluster I, are correlated to the approximately 180-250 mV difference between the reduction potentials of clusters I and II. These findings provide insight into the significant effects of subtle structural differences of the protein and solvent environment around the clusters of [4Fe-4S] ferredoxins on their electrochemical properties.

PubMed: 19290553
DOI: 10.1007/s00775-009-0492-x

Experimental method

X-RAY DIFFRACTION (1.05 Å)