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Free keywords:
Cell division; Geometry sensing; Microfabrication; Min proteins; Pattern formation; Protein gradients; Self-organization; Synthetic biology
Abstract:
The MinCDE protein system from Escherichia coli has become one of the
most striking paradigms of protein self-organization and biological
pattern formation. The whole set of Min proteins is functionally active
to position the divisome machinery by inhibiting Z ring assembly away
from mid-cell. This is accomplished by an oscillation behavior between
the cell poles, induced by the reaction between the two antagonistic
proteins MinD and MinE, which has long caught the attention of
quantitative biologists. Technical advances in fluorescence microscopy
and molecular biology have allowed us in the past years to reconstitute
this MinDE self-organization in cell-free environments on model
membranes. We verified the compositional simplicity of protein systems
principally required for biological pattern formation, and subjected the
mechanism to quantitative biophysical analysis on a single-molecule
level. On flat extended membranes, MinD and MinE self-organized into
parallel propagating waves. Moreover, employing microsystems technology
to construct membrane-clad soft polymer compartments mimicking the shape
of native E. coli cells has further enabled us to faithfully reproduce
Min protein oscillations. We further investigated the response of this
self-organizing molecular system to three-dimensional compartment
geometry. We could show that Min protein patterns depend strongly on the
size and shape of the compartment, and the oscillation axis can only be
preserved within a certain length interval and narrow width of the
compartment. This renders the Min system a perfectly adapted oscillator
to the bacterial cell geometry.
