Studie über die Genregulation der Expression der 3alpha-Hydroxysteroid-Dehydrogenase im Bakterium Comamonas testosteroni

Comamonas testosteroni 3alpha-hydroxysteroid dehydrogenase/carbonyl reductase (3alpha-HSD/CR) is a key enzyme in the degradation of steroid compounds in soil, and may therefore play a significant role in the bioremediation of hormonally active compounds in the environment. The enzyme is also involved in the degradation of the steroid antibiotic fusidic acid, thereby providing resistance of C. testosteroni towards this fungal product. In addition, 3alpha-HSD/CR mediates the carbonyl reduction of non-steroidal aldehydes and ketones, such as a novel insecticide, which suggests that this enzyme protects C. testosteroni against man-made toxicants. Since the gene of 3alpha-HSD/CR is inducible by steroids, we were interested in the mode of its molecular regulation. We have identified the first molecular determinant in procaryotic steriod-signalling. Recently, we could identify and clone a second novel regulator gene which we named repB.