Project Abstract

A novel genetic toggle switch regulated at the translational level was engineered in yeast that allowed the mutually exclusive expression of either green or cyan fluorescent protein. Using cell cytometry (FACS) and fluorimetry, we demonstrated in yeast the successful expression and translational regulation of a fusion of mRNA binding protein and fluorescent protein. These results, along with published parameter values, were used to predict via deterministic and stochastic models that the probability of successful bistability for our switch was 0.96%, but this could be improved theoretically to a maximum of 51.27% by limiting the range of variation of the most sensitive parameters. The models also predicted that co-operative binding of the mRNA binding protein to its mRNA stem loop was essential for generating switch-like behaviour. These results suggest that a translationally regulated genetic toggle switch is a viable and novel engineering concept applicable to medicinal, environmental and technological problems.

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