Amino acid residues in I- and K-helices of rat CYP11B1 and CYP11B2 are important in expression of 18-hydroxylation activity.
When a peptide of the 316-398th amino acid residues in CYP11B1 was inserted to the corresponding site in CYP11B2, the 18-hydroxylation activity of the chimera decreased to a level similar to that of CYP11B2. Site-directed mutagenesis studies indicated that this alteration in the activity was due to the change of one amino acid, Ser321-->Pro, which is present at the C-terminal side of enzyme's I-helix. Conversely, when the corresponding region of CYP11B2 was changed to that of CYP11B1, the 18-hydroxylation activity increased to the similar level as that of CYP11B1. This elevation of the activity seemed to be due to the exchange of two amino acid residues; one, the 321st residue and the other, the 381st located in the K-helix. The results are discussed in comparison with those obtained by the human isozymes.
Nonaka
Y
Y
Department of Basic Laboratory Sciences, Osaka University, Japan.
Fujii
T
T
Bernhardt
R
R
Okamoto
M
M
D000595:Amino Acid Sequence / Q000235:genetics / Q000502:physiology; D000818:Animals; D002678:Chimera / Q000235:genetics; D019405:Cytochrome P-450 CYP11B2 / Q000235:genetics* / Q000378:metabolism*; D004251:DNA Transposable Elements / Q000235:genetics; D006900:Hydroxylation; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000235:genetics; D017433:Protein Structure, Secondary; D051381:Rats; D013252:Steroid 11-beta-Hydroxylase / Q000235:genetics* / Q000378:metabolism*
D004251:DNA Transposable Elements; D010446:Peptide Fragments; D019405:Cytochrome P-450 CYP11B2; D013252:Steroid 11-beta-Hydroxylase