1m2d
Crystal structure at 1.05 Angstroms resolution of the Cys59Ser variant of the thioredoxin-like [2Fe-2S] ferredoxin from Aquifex aeolicus
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OverviewOverview
The [2Fe-2S] ferredoxin (Fd4) from Aquifex aeolicus adopts a, thioredoxin-like polypeptide fold that is distinct from other [2Fe-2S], ferredoxins. Crystal structures of the Cys-55 --> Ser (C55S) and Cys-59, --> Ser (C59S) variants of this protein have been determined to 1.25 A and, 1.05 A resolution, respectively, whereas the resolution of the wild type, (WT) has been extended to 1.5 A. The improved WT structure provides a, detailed description of the [2Fe-2S] cluster, including two features that, have not been noted previously in any [2Fe-2S] cluster-containing protein, namely, pronounced distortions in the cysteine coordination to the cluster, and a Calpha-H-Sgamma hydrogen bond between cluster ligands Cys-55 and, Cys-9. These features may contribute to the unusual electronic and, magnetic properties of the [2Fe-2S] clusters in WT and variants of this, ferredoxin. The structures of the two variants of Fd4, in which single, cysteine ligands to the [2Fe-2S] cluster are replaced by serine, establish, the metric details of serine-ligated Fe-S active sites with unprecedented, accuracy. Both the cluster and its surrounding protein matrix change in, subtle ways to accommodate this ligand substitution, particularly in terms, of distortions of the Fe(2)S(2) inorganic core from planarity and, displacements of the polypeptide chain. These high resolution structures, illustrate how the interactions between polypeptide chains and Fe-S active, sites reflect combinations of flexibility and rigidity on the part of both, partners; these themes are also evident in more complex systems, as, exemplified by changes associated with serine ligation of the nitrogenase, P cluster.
About this StructureAbout this Structure
1M2D is a Single protein structure of sequence from Aquifex aeolicus with FES as ligand. Full crystallographic information is available from OCA.
ReferenceReference
High resolution crystal structures of the wild type and Cys-55-->Ser and Cys-59-->Ser variants of the thioredoxin-like [2Fe-2S] ferredoxin from Aquifex aeolicus., Yeh AP, Ambroggio XI, Andrade SL, Einsle O, Chatelet C, Meyer J, Rees DC, J Biol Chem. 2002 Sep 13;277(37):34499-507. Epub 2002 Jun 27. PMID:12089152 [[Category: [2fe-2s] cluster]]
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