title: Conversion of vitamin D3 to 1alpha,25-dihydroxyvitamin D3 by Streptomyces griseolus cytochrome P450SU-1.
abstract: Streptomyces griseolus cytochrome P450SU-1 (CYP105A1) was expressed in Escherichia coli at a level of 1.0 micromol/L culture and purified with a specific content of 18.0 nmol/mg protein. Enzymatic studies revealed that CYP105A1 had 25-hydroxylation activity towards vitamin D2 and vitamin D3. Surprisingly, CYP105A1 also showed 1alpha-hydroxylation activity towards 25(OH)D3. As mammalian mitochondrial CYP27A1 catalyzes a similar two-step hydroxylation towards vitamin D3, the enzymatic properties of CYP105A1 were compared with those of human CYP27A1. The major metabolite of vitamin D2 by CYP105A1 was 25(OH)D2, while the major metabolites by CYP27A1 were both 24(OH)D2 and 27(OH)D2. These results suggest that CYP105A1 recognizes both vitamin D2 and vitamin D3 in a similar manner, while CYP27A1 does not. The Km values of CYP105A1 for vitamin D2 25-hydroxylation, vitamin D3 25-hydroxylation, and 25-hydroxyvitamin D3 1alpha-hydroxylation were 0.59, 0.54, and 0.91 microM, respectively, suggesting a high affinity of CYP105A1 for these substrates.
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Sawada
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakaki
authors.forename: Sachiyo
authors.initials: S
authors.lastname: Yoneda
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kusudo
authors.forename: Raku
authors.initials: R
authors.lastname: Shinkyo
authors.forename: Miho
authors.initials: M
authors.lastname: Ohta
authors.forename: Kuniyo
authors.initials: K
authors.lastname: Inouye
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D002117:Calcitriol / Q000138:chemical synthesis*; D002762:Cholecalciferol / Q000737:chemistry*; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D008970:Molecular Weight; D010105:Oxygenases / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D002762:Cholecalciferol; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; C086254:P450SU1 protein, Streptomyces griseolus; D002117:Calcitriol