Dresden 2009 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 18: Regulation and Signaling
BP 18.10: Vortrag
Donnerstag, 26. März 2009, 12:30–12:45, HÜL 186
Quorum signal integration in the B. subtilis sporulation phosphorelay — •Ilka Bischofs1, Josh Hug2, Aiwen Liu2, Denise Wolf1, and Adam Arkin1,2 — 1Lawrence Berkeley Lab, Berkeley, USA — 2UC Berkeley, Berkeley, USA
The phosphorelay is a central signal transduction structure in B. subtilis that integrates numerous cues including starvation and cell density signals in order to determine whether to commit to spore formation. Based on a theoretical model we demonstrate that the phosphorelay can act as a computational machine performing a sensitive division operation of inductive kinase encoded signals by instructive quorum modulated phosphatase signals, indicative of cells computing a "food per cell" estimate. In addition, we show experimentally that at least one quorum operon is heterogeneously induced in sporulating microcolonies. Cells delaying sporulation sustain quorum signal expression during periods of active growth, while cells committing to sporulation do not. Together with the model these findings suggest that the phosphorelay normalizes environmental signals by the size of the subpopulation actively competing for nutrients.