Role of aromatic residues in stabilization of the [Fe4S4] cluster in high-potential iron proteins (HiPIPs): physical characterization and stability studies of Tyr-19 mutants of Chromatium vinosum HiPIP.
AUTOR(ES)
Agarwal, A
RESUMO
The functional role of residue Tyr-19 of Chromatium vinosum HiPIP has been evaluated by site-directed mutagenesis experiments. The stability of the [Fe4S4] cluster prosthetic center is sensitive to side-chain replacements. Polar residues result in significant instability, while nonpolar residues (especially with aromatic side chains) maintain cluster stability. Two-dimensional NMR data of native and mutant HiPIPs are consistent with a model where Tyr-19 serves to preserve the structural rigidity of the polypeptide backbone, thereby maintaining a hydrophobic barrier for exclusion of water from the cluster cavity. Solvent accessibility results in more facile oxidation of the cluster by atmospheric oxygen, with subsequent rapid hydrolysis of the [Fe4S4]3+ core.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=40817Documentos Relacionados
- Dependence of the rates of dissolution of the Fe4S4 clusters of Chromatium vinosum high-potential iron protein and ferredoxin on cluster oxidation state
- Proton Magnetic Resonance Studies of Chromatium High-Potential Iron Protein
- A Comparison of Fe4S4 Clusters in High-Potential Iron Protein and in Ferredoxin
- Photooxidation of the high-potential iron—sulfur center in chloroplasts
- Gene Cluster of Rhodothermus marinus High-Potential Iron-Sulfur Protein:Oxygen Oxidoreductase, a caa3-Type Oxidase Belonging to the Superfamily of Heme-Copper Oxidases
