Quantitative Modeling the Saccharomyces cerevisiae FLR1 Regulatory Network Using an S-System Formalism

We address the problem of finding a mathematical model for the genetic network regulating the stress response of the yeast Saccharomyces cerevisiae to the fungicide mancozeb. An S-system formalism was used to model the interactions of this 5 gene network. Parameter estimation was accomplished by decoupling the resulting system of nonlinear ordinary differential equations into a larger nonlinear algebraic system, and using the Levenberg-Marquardt algorithm to fit the models predictions to experimental data. The introduction of constraints in the model, related to the putative topology of the network, was explored. The results show that forcing the network connectivity to adhere to this topology did not lead to better results than the ones obtained using an unrestricted network topology. Overall, the modeling approach obtained partial success when trained on the non-mutant datasets, although further work is required if one wishes to obtain more accurate prediction of the time courses.