Actin Polymerizing Motors to Assist Cytoskeleton-like Networks Formation in Artificial Cells

Artificial cells are man-made systems that imitate specific
functions
of biological cells to study or harness cellular behavior. Biological
cells can respond to external forces and signals by altering their
shape, undergoing deformation, and generating the mechanical forces
required for their movement. The cytoskeleton orchestrates this process
through the coordinated action of actin filaments, intermediate filaments,
and microtubules. Examples of artificial cells that sense and adapt
to changes in their environment owing to cytoskeleton rearrangement
have extensively been explored. These efforts focus on the use of
biomolecules that stochastically self-assemble in the lumen of an
artificial cell. Here, we employ actin polymerizing nanomotors to
assist cytoskeleton formation inside artificial cells. Nano- and micromotors
are a class of active colloids that can self-propel outperforming
Brownian motion. Inspired by natures’ way of leveraging biopolymerization
reactions to sustain locomotion in microorganisms or in organelles
within cells, we imitate the mechanism of motion of the food-born
bacteria Listeria monocytogenes. Specifically,
we coat polystyrene particles with an actin recruiting protein that
allows for actin filament polymerization in a mammalian cell lysate
environment. This polymerization results in up to a 3-fold increase
in the propulsion of the motors compared to their Brownian motion.
Lastly, we show that these motors can be encapsulated inside hybrid
vesicle-based artificial cells made of amphiphilic block copolymers
and phospholipids, forming actin filaments that assemble into a cytoskeleton-like
network. Taken together, this effort highlights the synergistic integration
of bottom-up synthetic biology and active matter, demonstrating how
their convergence can advance the design of life-like systems.