IMPROVED PURIFICATION OF STEROID 1-2-DEHYDROGENASE FROM NOCARDIA-OPACA AND PARTIAL CHARACTERIZATION OF ITS CLONED GENE SEQUENCE

We have purified a steroid-inducible 1:2-dehydrogenase from Nocardia opaca. The final enzyme preparation was purified 120-fold with a recovery of 38%. The N-terminal amino acid sequence was determined to be: Met-Gln-Asp- Trp-Thr-Ser-Glu-(Cys)-Asp-Val-Leu-Val-Val-Gly-. From the genomic library of Nocardia opaca in the plasmid pUC19, a clone designated as pSTD23 containing a 0.9 kb KpnI-PstI fragment was found to hybridize with an oligonucleotide probe corresponding to the first six amino acids from the N-terminal of the purified protein. The nucleotide sequence of the upstream region and a part of the structural domain were determined. The sequence of the first 56 amino acids of the steroid 1:2-dehydrogenase from Nocardia opaca as deduced from its gene sequence showed a 58% homology with the corresponding gene from Pseudomonas testosteroni, and the conservative sequences in the FAD-binding domain were also determined. © 1993 Academic Press, Inc.