Mark J. Arcario and Emad Tajkhorshid.
Membrane-induced structural rearrangement and identification of a
novel membrane anchor in Talin F2F3.
Biophysical Journal, 107:2059-2069, 2014.
(PMC: PMC4223205)
ARCA2014-ET
Experimental challenges associated with characterization of the membrane-bound form of
talin have prevented us from understanding the molecular mechanism of its membrane-
dependent integrin activation. Here, utilizing what we believe to be a novel membrane
mimetic model, we present a reproducible model of membrane-bound talin observed
across multiple independent simulations. We characterize both local and global
membrane-induced structural transitions that successfully reconcile discrepancies between
biochemical and structural studies and provide insight into how talin might modulate
integrin function. Membrane binding of talin, captured in unbiased simulations, proceeds
through three distinct steps: initial electrostatic recruitment of the F2 subdomain to
anionic lipids via several basic residues; insertion of an initially buried, conserved
hydrophobic anchor into the membrane; and association of the F3 subdomain with the
membrane surface through a large, interdomain conformational change. These latter two
steps, to our knowledge, have not been observed or described previously. Electrostatic
analysis shows talin F2F3 to be highly polarized, with a highly positive underside, which we
attribute to the initial electrostatic recruitment, and a negative top face, which can help
orient the protein optimally with respect to the membrane, thereby reducing the number of
unproductive membrane collision events.
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