Compendium of wheat diseases. Second edition.

Abstract

CYP19 (P450arom) catalyzes the aromatization reaction of C19 steroids leading to estrogens. While readily expressed in insect cells, the human P450arom has been a difficult P450 to express in Escherichia coli at useful levels. In the present study, we replaced the N-terminal sequence in human CYP19 with the corresponding sequences of other microsomal P450s (CYP2C11 and CYP17) that are efficiently expressed in E. coli. Although the N-terminal replacement alone was not sufficient for the expression, human P450arom was successfully expressed up to the level of 240nmol/l culture by the combination of the N-terminal replacement and the induction of cold stress response by 1 microg/ml chloramphenicol. Membrane fractions containing the expressed P450arom catalyzed aromatization of androstenedione with a specific activity of 4.9 nmol/min/nmol P450. Our results are important to provide large quantities of human P450arom as an active form for structure-function studies.