Steroid transformation by Rhodococcus strains and bacterial cytochrome p450 enzymes

PhD ceremony: Ms. K.Z du Plessis-Rosloniec, 11.00 uur, Academiegebouw, Broerstraat 5, Groningen

Title: Steroid transformation by Rhodococcus strains and bacterial cytochrome p450 enzymes

Promotor(s): prof. L. Dijkhuizen

Faculty: Mathematics and Natural Sciences

The thesis of Kamila du Plessis-Rosłoniec describes activities of four bacterial steroid-induced cytochrome P450 enzymes in terms of their potential biotechnological use for steroid transformations by engineered Rhodococcus strains into commercially interesting compounds. Three selected rhodococcal P450 enzymes were characterized by her by means of microbiological, genetic, biochemical, spectroscopic and chromatographical methods. Two sterol C26-hydroxylases were shown to be important for 3-hydroxysterol degradation. The role of the novel dextromethorphan N-demethylase in sterol metabolism was analysed. Furthermore, heterologous production of a mutated P450 enzyme from Bacillus megaterium was described in an engineered Rhodococcus strain. The activity of the biocatalyst on 4-androstene-3,17-dione was identified as 16β-hydroxylase by 1H and 13C NMR. The detailed characterization of the cytochrome P450 enzymes, described in the thesis of Du Plessis, provides insight into the catabolic repertoire of Rhodococcus strains, necessary for engineering of steroid catabolic pathways for production of valuable pharmaceuticals.