Molecular characterization of three 3-ketosteroid-Delta(1)-dehydrogenase isoenzynnes of Rhodococcus ruber strain Chol-4

摘要: Rhodococcus ruber strain Chol-4 isolated from a sewage sludge sample is able to grow on minimal medium supplemented with steroids, showing broad catabolic capacity. This paper reports the characterization of three different 3-ketosteroid-Δ(1)-dehydrogenases (KstDs) in genome R. Chol-4. The this does not contain any homologues 3-keto-5α-steroid-Δ(4)-dehydrogenase (Kst4d or TesI) that appears genomes erythropolis SQ1 Comamonas testosteroni. Growth experiments kstD2 mutants, either single mutant, double mutants combination kstD1 kstD3, triple kstD1,2,3 proved KstD2 involved transformation 4-androstene-3,17-dione (AD) 1,4-androstadiene-3,17-dione (ADD) and conversion 9α-hydroxy-4-androstene-3,17-dione (9OHAD) 9α-hydroxy-1,4-androstadiene-3,17-dione (9OHADD). kstD2,3 (both lacking KstD3) did cholesterol as only carbon source, thus demonstrating involvement KstD3 degradation. In contrast, mutation alter bacterial growth steroids tested study therefore, role protein still remains unclear. absence functional provoked all cases an accumulation 9OHAD, branch product probably formed by action 3-ketosteroid-9α-hydroxylase (KshAB) AD molecule. Therefore, key enzyme catabolism pathway while catabolism.