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AKB: Biologische Physik

AKB 16: Biological Networks

AKB 16.1: Hauptvortrag

Mittwoch, 29. März 2006, 14:00–14:30, ZEU 255

Biological Networks: Design Principles of Robust Information Processing — •Markus Kollmann — University of Freiburg, Institute of Physics, Hermann-Herder-Str. 3, 79104 Freiburg

Cellular biochemical networks have to function in a noisy environment using imperfect components. In particular, networks involved in gene regulation or signal transduction allow only for small output tolerances and the underlying network structures can be expected to have undergone evolution for inherent robustness against perturbations. We combined theoretical and experimental analysis to investigate an optimal design for the signalling network of bacterial chemotaxis, one of the most thoroughly studied signalling networks in biology. We experimentally determined the extent of intercellular variations in expression levels of chemotaxis proteins and use computer simulations to quantify the robustness of several hypothetical chemotaxis pathway topologies to such gene expression noise. We demonstrate that the experimentally established topology of the chemotaxis network in Escherichia coli is one of the smallest sufficiently robust structures, allowing accurate chemotactic response for almost all individuals within a population. Our results suggest that this pathway has evolved to show an optimal chemotactic performance while minimising the cost of resources associated with high levels of protein expression. Moreover, the underlying topological design principles compensating for intercellular variations seem to be highly conserved among bacterial chemosensory systems.

∖Zitat{1}{M. Kollmann, L. Lovdok, K. Bartholome, J. Timmer, and V. Sourjik, Nature, in press }