Glu43 is an essential residue for coordinating the [Fe2S2] cluster of IscR from Acidithiobacillus ferrooxidans

The iron-sulfur cluster regulator (IscR) was reported to be a repressor of the iscRSUA operon. In vitro transcription reactions revealed that the IscR had a repression effect on the iscR promoter. The IscR contains a [Fe(2)S(2)] cluster per each monomer, and three highly conserved cysteines were identified to ligate the [Fe(2)S(2)] cluster. It was proposed that a non-cysteine residue might be the fourth ligand for the [Fe(2)S(2)] cluster. In this study, using site-directed mutagenesis, Glu43 was found to be the fourth residue that coordinates the [Fe(2)S(2)] cluster of IscR. (C) 2008 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.