bm500988r_si_003.avi (433.69 kB)
Single Filament Behavior of Microtubules in the Presence of Added Divalent Counterions
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posted on 2014-10-13, 00:00 authored by Nathan
F. Bouxsein, George D. BachandMicrotubules (MTs) are hollow biopolymeric
filaments that function
to define the shape of eukaryotic cells, serve as a platform for intracellular
vesicular transport, and separate chromosomes during mitosis. One
means of physiological regulation of MT mechanics and dynamics, critical
to their adaptability in such processes, is through electrostatics
due to the strong polyelectrolyte nature of MTs. Here, we show that
in the presence of physiologically relevant amounts of divalent salts,
MTs experience a dramatic increase in persistence length or stiffness,
which is counter to theoretical expectations and experimental observations
in similar systems (e.g., DNA). Divalent salt-dependent effects on
MT dynamics were also observed with respect to suppressing depolymerization
as well as reducing dispersion in kinesin-driven molecular motor transport
assays. These results establish a novel mechanism by which MT dynamics,
mechanics, and interaction with molecular motors may be regulated
by physiologically relevant concentrations of divalent salts.