NMR Approaches to the Study of Structure-Function Relationships in Iron-Sulfur Proteins

Abstract

A review with 80 refs. Newer NMR methods, particularly in conjunction with stable isotope labeling (with 2H, 13C, and 15N), offer powerful approaches to the elucidation of structure-function relationships in paramagnetic proteins such as iron-sulfur proteins. The optimization of NMR pulse sequences for rapidly-relaxing spins and the utilization of multidimensional multinuclear NMR spectroscopy have made it possible to det. sequence-specific assignments for a larger no. of NMR signals in rubredoxins, ferredoxins, and high-potential iron proteins, including some from the cysteine residues that ligate the iron ions. Such assignments are the key to a wealth of information derived from NMR parameters, such as the temp. and pH dependence of chem. shifts and the relaxation properties of the resonances that report on interactions between nuclei of the protein and unpaired electron d. from the metal center. This information can be used to test theor. descriptions of electron distribution within these mols. and to model the structures and dynamic properties of the proteins in soln. Mutagenesis of these proteins, followed by biochem. evaluation of their functional properties and biophys. anal. of their structures and stabilities, is beginning to reveal which residues are important for cluster formation and which residues play a role in electron transfer to and from redox partner proteins. This review discusses recent NMR studies from our lab. of six iron-sulfur proteins: Clostridium pasteurianum rubredoxin, the vegetative and heterocyst ferredoxins from Anabaena 7120, human ferredoxin, and the Pseudomonas mendocina KR1 tmoC Rieske protein. [on SciFinder(R)]