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GRASP Seminar Series: Fall 2007
Novemer 2, 11:00 a.m., Wu & Chen Auditorium, Levine Hall (3330 Walnut Street)
Domitilla del Vecchio
University
of Michigan
"Modular Cell Biology: Retroactivity and Insulation"
Abstract: Modularity
plays a fundamental role in the prediction of the behavior of a system
from the behavior of its components, guaranteeing that the properties
of individual components do not change upon interconnection. Just as
electrical, hydraulic, and other physical systems often do not display
modularity, nor do many biochemical systems, and specifically, genetic
networks. Here, we study the effect of interconnections on the input/output
dynamic characteristics of transcriptional components, focusing on a
property, which we call "retroactivity," that
plays a role analogous to non-zero output impedance in electrical systems.
In transcriptional networks, retroactivity is large when the amount of
transcription factor is comparable to, or smaller than, the amount of
promoter binding sites, or when the affinity of such binding sites is
high. In order to attenuate the effect of retroactivity, we propose a
feedback mechanism inspired by the design of amplifiers in electronics.
We introduce,
in particular, a mechanism based on a phosphorylation/dephosphorylation
cycle. This mechanism enjoys a remarkable insulation property, due to
the fast time scales of the phosphorylation and dephosphorylation reactions.
Biography: Domitilla del Vecchio is Assistant Profesor of Electrical Engineering and Computer Science at the University of Michigan, Ann Arbor. She received her Ph.D. in Control and Dynamical Systems from Caltech in 2005. Her research interests include state estimation and control in multi-agent decision and control systems, and modular design of gene transcriptional circuits.
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