1m2b
Crystal structure at 1.25 Angstroms resolution of the Cys55Ser variant of the thioredoxin-like [2Fe-2S] ferredoxin from Aquifex aeolicus
Structural highlights
FunctionFER2_AQUAE Ferredoxins are iron-sulfur proteins that transfer electrons in a wide variety of metabolic reactions. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe [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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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