Structure-function studies on mutants of adrenal ferredoxin.

Mutants of the adrenal ferredoxin (adrenodoxin) have been expressed in E. coli in order to improve the understanding of its structure and function. Replacement of the ligands to the /2Fe-2S/ center, C46, C52, C55 and C92, by serine, histidine or aspartic acid lead to apoproteins not incorporating the iron-sulfur cluster, whereas C95S forms a functionally active holoprotein. C-terminal deletions up to amino acid 109 affect the conformation around the iron-sulfur cluster in adrenodoxin and the interaction with CYP11A1 and CYP11B1, but not with adrenodoxin reductase. The presence of P108 is necessary for incorporation of the /2Fe-2S/ cluster and obviously for correct folding of adrenodoxin.