Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 5: Systems Biology & Gene Expression and Signalling

BP 5.3: Vortrag

Montag, 12. März 2018, 15:30–15:45, H 1028

Computational analysis on the regulation of σ/anti-σ factor operons — •Hao Wu and Georg Fritz — LOEWE Center for Synthetic Microbiology, Phlipps University Marburg, Germany

Bacterial alternative σ factors are subunits of RNA polymerase that determine its promoter specificity, thereby regulating crucial processes like cell homeostasis and stress responses. In the absence of input signals, σ factors are sequestered by their cognate anti-σ factors. Meanwhile, many σ/anti-σ factor pairs are co-expressed in operons, most of them are auto-regulated by the σ factor, implying a regulation module with a positive and a negative feedback at the same time. Strikingly, there are two distinct mechanisms to activate this module: One involves the active degradation of anti-σ factors upon input signal detection, constituting a non-equilibrium sensing mechanism, while the other one relies on a reversible conformational change of the anti-σ factor to a non-functional form, resembling an equilibrium sensing mechanism. Here we conducted a comprehensive computational study on the quantitative properties of this important regulatory module. While many characteristics prove independent of the sensing mechanism, we identified some major differences between their dynamical properties. Interestingly, in the responsive regime the activation of σ factor level becomes very slow for the non-equilibrium sensing mechanism, while it remains fast for the equilibrium sensing mechanism. These results deepen our understanding of the σ/anti-σ factor regulation module and help us to explain the choice of the two distinct sensing mechanisms in different physiological contexts.