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BP: Fachverband Biologische Physik

BP 32: Posters: Other Topics in Biological Physics

BP 32.6: Poster

Donnerstag, 17. März 2011, 17:15–20:00, P3

Sequential gene-regulatory logic: Design schemes and quantitative characteristics — •Patrick Hillenbrand, Georg Fritz, and Ulrich Gerland — Department of Physics and CeNS, LMU München

Epigenetic memory plays a pivotal biological role in bacteria and eukaryotes alike, and permits the transient storage of information. In digital electronics, logic elements that involve the processing of internal memory states are referred to as sequential logic circuits. The basic elements of sequential logic are addressable one-bit memory elements (so-called latches). Here, we study a genetic equivalent of the most versatile such element, the genetic J-K latch. The J-K latch is able to stably hold its state, and to perform the operations `set', `reset', and `toggle'. Our analysis indicates that designs based on protein-protein interaction and protein-DNA binding, are in principle sufficient to implement the desired functionality. We show that stable oscillations are necessary for the circuit to faithfully switch its state upon the toggle command. These oscillations are generated by a time delay in the system caused by overlapping protein binding sites on the DNA. Finally, we also discuss an extension of the genetic J-K latch to a master-slave latch, which switches its state upon a toggle signal without displaying oscillatory behavior. The master-slave latch exhibits a particularly robust functionality, is a useful element for synthetic biology, and may be employed also in natural regulatory circuits.