Grischa Raphael Meyer, Justin Gullingsrud, Klaus Schulten, and Boris Martinac.
Molecular dynamics study of MscL interactions with a curved lipid
bilayer.
Biophysical Journal, 91:1630-1637, 2006.
(PMC: 1544281)
MEYE2006
Mechanosensitivity is a ubiquitous sensory mechanism found in living
organisms. The simplest known mechanotransducing mechanism is found
in bacteria in form of the mechanosensitive membrane channel of large
conductance, MscL. This channel has been studied extensively using a
variety of methods at a functional and structural level. The channel
is gated by membrane tension in the lipid bilayer alone. It serves as
a safety valve protecting bacterial cells against hypoosmotic shock.
MscL of Escherichia coli embedded in bilayers composed of asymmetric
amounts of single tailed and double tailed lipids has been shown to
gate spontaneously, even in the absence of membrane tension. To gain
insight into the effect of the lipid membrane composition and
geometry on MscL structure, a fully solvated, all-atom model of MscL
in a stress- free curved bilayer composed of double and single tailed
lipids was studied using a 9.5ns molecular dynamics simulation. The
bilayer was modeled as a domed structure accommodating the asymmetric
composition of the monolayers. During the course of the simulation a
spontaneous restructuring of the periplasmic loops occurred, leading
to interactions between one of the loops and phospholipid headgroups.
Previous experimental studies of the role of the loops agree with the
observation that opening starts with a restructuring of the
periplasmic loop, suggesting an effect of the curved bilayer. Due to
limited resources only one simulation of the large system was
performed. However, the results obtained suggest that through the
geometry and composition of the bilayer the protein structure can be
affected even on short timescales.
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