title: Developing a compound-specific receptor for bisphenol A by directed evolution of human estrogen receptor α.
abstract: Directed evolution has become a successful approach to alter ligand binding properties of nuclear receptors. In this study, directed evolution was used to generate a mutant human estrogen receptor α library, which was then used to screen for receptors having enhanced responses to the known endocrine-disrupting chemical, bisphenol A (BPA). A single round of multi-site mutation was combined with an efficient positive/negative library screening method in which positive growth-based selection for the desired activity with BPA was combined with flow cytometric removal of cells having undesired activity with the natural ligand, 17β-estradiol. The screening steps were performed in a Saccharomyces cerevisiae yeast strain containing a genome-integrated his3-yEGFP reporter gene fusion construct. A single round of mutation and screening yielded nine mutants with enhanced responses towards BPA but no detectable induction by 17β-estradiol (up to 90 nM). These BPA-specific mutant receptors may prove useful in the field of environmental analytics, where they could be used to monitor and evaluate the proportion of BPA in hormonally active samples.
authors: Department of Food and Environmental Sciences, University of Helsinki, PO Box 56 (Viikinkaari 9), 00014, 00790 Helsinki, Finland. johanna.rajasarkka@helsinki.fi
authors: Johanna
authors: J
authors: Rajasärkkä
authors: Kaisa
authors: K
authors: Hakkila
authors: Marko
authors: M
authors: Virta