Abstract

A 4.8-kb DNA fragment encoding the P-450 type hydroxylase and ferredoxin genes was cloned from Pseudonocardia autotrophica IFO 12743 that can convert vitamin D_3 into its hydroxylated active forms. In order to isolate the P-450 gene cluster in this organism, we designed PCR primers on the basis of the regions of an oxygen binding site and a heme ligand pocket that are general characteristics of the P-450 hydroxylase. Sequencing analysis of the BamHI fragment revealed the presence of four complete and one incomplete ORFs, named PauA, PauB, PauC, and PauD, respectively. As a result of computer-based analyses, PauA and PauB have homology with enoyl-CoA hydratase from several organisms and the positive regulators belonging to the tetR family, respectively. PauC and PauD show similarity with SuaB/C proteins and ferredoxins, respectively, which are composed of P-450 monooxygenase systems for metabolizing two sulfonylurea herbicides in Streptomyces griseolus PauC shows the highest similarity with another CytP-450_Sca2 protein that is responsible for production of a specific HMG-CoA reductase inhibitor, pravastatin, in S. carbophilus. Cultures of Streptomyces lividans transformant, containing the P-450 gene cluster on the pWHM3 plasmid, was unable to convert vitamin D_3 to its hydroxylated forms.

• Keywords: P-450 hydroxylase; ferredoxin; Pseudonocardia autotrophica; biotransformation