The Interaction of Phytoestrogens with Modified Escherichia coli as a Biosensor for Different Animal Species
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Date
2014-12
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The Ohio State University
Abstract
The nuclear hormone receptors (NHRs) are important features of the cell, as they control activities of cell development, homeostasis, reproduction, and metabolism. Importantly, NHRs are also targets for naturally occurring and synthetic endocrine disrupting compounds. Any interference with their functioning has been connected to breast cancer, decreased fertility, osteoporosis, and other disorders in humans and other animals. We have constructed a very simple reporter system, or a biosensor, by modifying Escherichia coli by inserting an intein with the beta subtypes of the human estrogen receptor ligand-binding domain and thymidylate synthase reporter enzyme gene (D1210). With this modification, these E. coli cells can sense human estrogen and report their presence and interactions through changes in growth phenotype. The modified E. coli cells are referred to as biosensors and they have capabilities to distinguish estrogen agonistic growth and antagonistic suppression activities and report rough estimates of binding affinity. In this study, we will be conducting experiments to investigate the interactions of plant-derived estrogens, or phytoestrogens, and their estrogenic potency. In order to generate the data, biosensor cells are cultured in thymine-less media, and are introduced to test ligands. The biosensor growth phenotype allows the identification of which phytoestrogens will yield a similar potency to estrogen. The growth phenotype were determined by measuring the optical density (OD600) at wavelength of 600 nm. Our experiment results suggest that genistein and daidzein, which belongs to the category of isoflavones, yield similar potencies as estrogen. Comparisons between the tested phytoestrogens binding affinity were also studied and reported. While the estrogenic potency of industrial-originated estrogenic compounds is very limited, the findings of this study can hopefully reveal the estrogenic potency of phytoestrogens and also reveal what may trigger many of the biological responses that are evoked by the phytoestrogens and its ability to be a potential remedy for advanced endocrine related cancer.
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Phytoestrogens Modified Biosensor E. coli Endocrine Ligand