IscS from Archaeoglobus fulgidus has no desulfurase activity but may provide a cysteine ligand for [Fe2S2] cluster assembly.

Abstract : Iron sulfur ([Fe-S]) clusters are essential prosthetic groups involved in fundamental cell processes such as gene expression regulation, electron transfer and Lewis acid base chemistry. Central components of their biogenesis are pyridoxal-5'-phosphate (PLP) dependent l-cysteine desulfurases, which provide the necessary S atoms for [Fe-S] cluster assembly. The archaeon Archaeoglobus fulgidus (Af) has two ORFs, which although annotated as l-cysteine desulfurases of the ISC type (IscS), lack the essential Lys residue (K199 in Af) that forms a Schiff base with PLP. We have previously determined the structure of an Af(IscU-D35A-IscS)2 complex heterologously expressed in Escherichia coli and found it to contain a [Fe2S2] cluster. In order to understand the origin of sulfide in that structure we have performed a series of functional tests using wild type and mutated forms of AfIscS. In addition, we have determined the crystal structure of an AfIscS-D199K mutant. From these studies we conclude that: i) AfIscS has no desulfurase activity; ii) in our in vitro [Fe2S2] cluster assembly experiments, sulfide ions are non-enzymatically generated by a mixture of iron, l-cysteine and PLP and iii) the physiological role of AfIscS may be to provide a cysteine ligand to the nascent cluster as observed in the [Fe2S2]-Af(IscU-D35A-IscS)2 complex. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
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BBA - Biochimica et Biophysica Acta, Elsevier, 2015, 1853 (6), pp.1457-1463
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Soumis le : mardi 24 février 2015 - 09:53:44
Dernière modification le : lundi 19 février 2018 - 14:34:03

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  • HAL Id : hal-01119798, version 1
  • PUBMED : 25447670

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Adrien Pagnier, Yvain Nicolet, Juan-Carlos Fontecilla-Camps. IscS from Archaeoglobus fulgidus has no desulfurase activity but may provide a cysteine ligand for [Fe2S2] cluster assembly.. BBA - Biochimica et Biophysica Acta, Elsevier, 2015, 1853 (6), pp.1457-1463. 〈hal-01119798〉

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