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Functional expression of cDNAs for bovine 11 beta-hydroxylase-aldosterone synthases, P450(11 beta)-2 and -3 and their chimeras. |
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| Authors: | Yasuki Nonaka Mitsuhiro Okamoto Ken-Ichirou Morohashi Shirou Kirita Toshihide Hashimoto and Tsuneo Omura |
| Institution: | 1 Departments of Biochemistry and Molecular Physiological Chemistry, Osaka University Medical School, Kita-Ku, Osaka 530, Japan 2 Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Higashi-Ku, Fukoka 812, Japan |
| Abstract: | Two molecular species of bovine P450(11β), P450(11β)-2 and P450(11β)-3 have been identified, in which the amino acid differences were found at the 6th, 36th and 82nd positions from the NH2-termini of the mature proteins. They catalyzed the 11β-, 18- and 19-hydroxylation and aldosterone formation from 11-deoxycorticosterone, and the rate of production of 18-hydroxycorticosterone and aldosterone by P450(11β)-3 was greater than that by P450(11β)-2 Morohashi et al., J. Biochem. 107 (1990) 635–640]. In this study, chimeric clones were constructed whose 6th, 36th and 82nd amino acid residues were exchanged with each other. Two original clones and six chimeric clones were expressed in COS-7 cells, and their steroidogenic activities studied. The ratio of aldosterone or 18-hydroxycorticosterone production to corticosterone production by one clone was compared with that of the other. The ratios for the four clones having Gly36 P450(11β)-3 type] were 0.08–0.22, whereas those for the clones having Ser36 P450(11β)-2 type] were 0.03–0.05, suggesting that the Gly36 structure is important for aldosterone production. |
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