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Biochem J. 2005 Aug 1;389(Pt 3):797-802.

Mobilization of the iron centre in IscA for the iron-sulphur cluster assembly in IscU.

Author information

1
Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.

Abstract

The biogenesis of iron-sulphur clusters requires the co-ordinated delivery of both iron and sulphur. It is now clear that sulphur in iron-sulphur clusters is derived from L-cysteine by cysteine desulphurases. However, the iron donor for the iron-sulphur cluster assembly still remains elusive. Our previous studies indicated that Escherichia coli IscA, a member of the iron-sulphur cluster assembly machinery, is an iron-binding protein that can provide iron for the iron-sulphur cluster assembly in a proposed scaffold IscU. To determine how the iron centre in IscA is transferred for the iron-sulphur cluster assembly in IscU, we explore the mobility of the iron centre in IscA. The UV-visible and EPR measurements show that L-cysteine, but not IscU, is able to mobilize the iron centre in IscA and make the iron available for the iron-sulphur cluster assembly in IscU. Other related biological thiols such as N-acetyl-L-cysteine or reduced glutathione have no effect on the iron centre of IscA, suggesting that L-cysteine is unique in mobilizing the iron centre of IscA. Nevertheless, L-cysteine alone is not sufficient to transfer the iron from IscA to IscU. Both L-cysteine and cysteine desulphurase (IscS) are required for the IscA-mediated assembly of iron-sulphur clusters in IscU. The results suggest that L-cysteine may have two distinct functions in the biogenesis of iron-sulphur clusters: to mobilize the iron centre in IscA and to provide sulphur via cysteine desulphurase (IscS) for the iron-sulphur cluster assembly in IscU.

PMID:
15828873
PMCID:
PMC1180730
DOI:
10.1042/BJ20050405
[Indexed for MEDLINE]
Free PMC Article

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