The Study Of The Stabilization Of The [Fe4S4] Cluster In The High Redox Potential Iron-sulfur

The Iron oxidase Iro protein is a member of HiPIP family with the [Fe4S4] cluster for electron transfer. Many reports proposed that the conserved aromatic residues might be responsible for the stability of the iron-sulfur cluster in HiPIP. In this study, Tyr10 was found to be a critical residue for the stability of the [Fe4S4] cluster according to site-directed mutagenesis results. Tyr10, Phe26 and Phe48 were essential for the stability of the [Fe4S4] cluster under acidic condition. Trp44 were not involved in the stability of the [Fe4S4] cluster. Molecular structure modeling for the mutant Tyr10 proteins revealed that the aromatic group of Tyr10 may form a hydrophobic barrier to protect the [Fe4S4] cluster from solvent.The high potential iron-sulfur protein (HiPIP) from Acidithiobacillus ferrooxidans was proposed to be involved in the iron respiratory electron transport chain in Acidithiobacillus ferrooxidans. UV-Vis scanning and CD for the protein revealed that Tyrl5 was important for the stability of the [Fe4S4] cluster.