IMMUNOCYTOCHEMICAL LOCALIZATION OF HETEROLOGOUSLY EXPRESSED ADRENODOXIN AND ITS ELECTRON-ACCEPTOR CYTOCHROME P45011B1 IN ESCHERICHIA-COLI

Adrenal steroid hydroxylase P45011B1 and its electron donor adrenodoxi n were localized in the cortex of bovine adrenals by immunogold-silver staining. In order to test recently developed heterologous expression systems for both enzymes to enable structure-function studies, immuno cytochemical marker methods were applied. Adrenodoxin, the ferredoxin of the adrenal gland, was successfully expressed and for the first tim e localized in Escherichia coli. By use of ultrathin cryosections and the protein A-gold technique, adrenodoxin was detectable in large amou nts in the cytoplasm of the bacterial cells, and, following the insert ion of the outer membrane protein A leader sequence of E. coli, also i n the periplasmic space. A fusion protein between mature adrenodoxin a nd human P45011B1 was constructed and clearly localized in E. coli by antibodies against both proteins.