Iron-Sulfur Cluster Biosynthesis: Characterization of Iron Nucleation Sites for Assembly of the [2Fe-2S]2+ Cluster Core in IscU Proteins
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- 作者：Manunya Nuth ; Taejin Yoon ; and J. A. Cowan
- 刊名：Journal of the American Chemical Society
- 出版年：2002
- 出版时间：July 31, 2002
- 年：2002
- 卷：124
- 期：30
- 页码：8774 - 8775
- 全文大小：45K
- 年卷期：v.124,no.30(July 31, 2002)
- ISSN：1520-5126
文摘
ISU (eukaryotes) and IscU (prokaryotes) are a homologous family of proteins that appear to provide a platform for assembly of [2Fe-2S] centers prior to delivery to a target apoprotein. The intermediate [2Fe-2S] IscU-bound cluster is formed by delivery of iron and sulfur to the apo-IscU, with the latter delivered through an IscS-mediated reaction. The identity of the iron donor is not yet established. In this report we characterize iron-binding sites on IscU that appear to nucleate [2Fe-2S] cluster assembly. This iron-bound form of IscU is shown to be viable for subsequent IscS-mediated assembly of holo-IscU. Following on recent reports, we demonstrate the persulfide form of IscU to be a dead-end complex that is incapable of forming holoprotein after addition of ferrous or ferric ion. The latter observation reflects the low binding affinity of persulfido IscU for iron ion.