jp5020077_si_002.avi (14.49 MB)
Fibronectin Module FNIII9 Adsorption at Contrasting Solid Model Surfaces Studied by Atomistic Molecular Dynamics
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posted on 2014-08-21, 00:00 authored by Karina Kubiak-Ossowska, Paul A. Mulheran, Wieslaw NowakThe mechanism of human fibronectin
adhesion synergy region (known
as integrin binding region) in repeat 9 (FNIII9) domain
adsorption at pH 7 onto various and contrasting model surfaces has
been studied using atomistic molecular dynamics simulations. We use
an ionic model to mimic mica surface charge density but without a
long-range electric field above the surface, a silica model with a
long-range electric field similar to that found experimentally, and
an Au {111} model with no partial charges or electric field. A detailed
description of the adsorption processes and the contrasts between
the various model surfaces is provided. In the case of our model silica
surface with a long-range electrostatic field, the adsorption is rapid
and primarily driven by electrostatics. Because it is negatively charged
(−1e), FNIII9 readily adsorbs to a positively charged
surface. However, due to its partial charge distribution, FNIII9 can also adsorb to the negatively charged mica model because of
the absence of a long-range repulsive electric field. The protein
dipole moment dictates its contrasting orientation at these surfaces,
and the anchoring residues have opposite charges to the surface. Adsorption
on the model Au {111} surface is possible, but less specific, and
various protein regions might be involved in the interactions with
the surface. Despite strongly influencing the protein mobility, adsorption
at these model surfaces does not require wholesale FNIII9 conformational changes, which suggests that the biological activity
of the adsorbed protein might be preserved.