SEMINAR @ SISSA, SBP, L. Zhu - Jan. 24, @ 11.00 hrs

[Giovanni Bussi]

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STATISTICAL AND BIOLOGICAL PHYSICS SEMINAR
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Lizhe Zhu

(Computational Chemistry and Physics, Van't Hoff Institute of Molecular
Sciences, University of Amsterdam)****

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Title: Modeling mechanisms of transmembrane signaling


Abtract


Signal transduction happens at the cell surface as a signal ligand is
caught by the transmembrane (TM) receptor. Such ligand binding introduces a
change in the receptor protein and ultimately leads to cell responses. This
change of the receptor could not only be a conformational change but also a
change in the scale of its fluctuations. We discuss these two models of
mechanisms via two receptor systems. HAMP domains are part of bacteria
chemotaxis receptors crucial in relaying the signals. We find, via all-atom
molecular dynamics and well-tempered metadynamics, that the prototype HAMP
domain, when isolated, exhibits a collective motion yet with only one
stable conformation. Using replica exchange Monte Carlo sampling of a
simple model, we also show that integral membrane receptors, such as
G-Protein-Coupled-Receptors, can work purely via fluctuations, under the
condition that the receptor consists of at least four TM helices.

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Tue Jan. 24, 2012 @ 11.00 a.m.****

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SISSA – first floor – room 132
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