Single cell studies of bacterial two component systems (work in progress)

*Pamela David1, Orland Gonzalez1, Kirsten Jung2, Judith Leierseder3, Eduardo Mendoza1, 3 and Joachim Rädler 3
* Authors in alphabetical order
1 University of the Philippines Diliman
2 Biology Department, Ludwig-Maximilians-University
3 Physics Department, Ludwig-Maximilians-University

The response of biological systems to external stimuli is generally measured from an entire population. However the individual response of the cells is often widely distributed. Many effects that could elucidate the biological network are averaged out. In order to address the variance and underlying stochastic processes of signal transduction systems single cell analysis techniques shall be developed. The dynamics of gene expression in bacteria will be monitored by quantitative and time resolved image processing of GFP-hybrid proteins. This allows acquiring time traces of the protein content of individual cells, which are used as input for mathematical models. The analysis of many traces in an automated procedure measures the distribution of gene expression in a population. Single cell studies are likely to access stochastic events in the signal transduction pathway, which are the key to identify the functionality of molecular modules.

The talk will report on the progress of a recently initiated joint experimenter-modeller study of the EnvZ/OmpR system in E.coli. On the experimental side, techniques developed from the study of artificial virus transport in eukaryotic cells are being adapted by J. Leierseder, K. Jung and J. Rädler. On the computational side, approaches from modelling other two component systems (such as KdpD/KdpE in E.coli) with S-Systems will be adjusted by P. David, O. Gonzalez and E. Mendoza, to integrate data from the current experiments and the literature. In particular, simulated annealing will be used to estimate parameters directly from the time-course data generated.