Fabricating
artificial spider silk fibers in bulk scale has been
a major goal in materials science for centuries. Two main routes have
emerged for making such fibers. One method uses biomimetics in which
the spider silk proteins (spidroins) are produced under nativelike
conditions and then spun into fibers in a process that captures the
natural, complex molecular mechanisms. However, these fibers do not
yet match the mechanical properties of native silk fibers, potentially
due to the small size of the designed spidroin used. The second route
builds on biotechnological progress that enables production of large
spidroins that can be spun into fibers by using organic solvents.
With this approach, fibers that equal the native material in terms
of mechanical properties can be manufactured, but the yields are too
low for economically sustainable production. Hence, the need for new
ideas is urgent. Herein, we introduce a structural-biology-based approach
for engineering artificial spidroins that circumvents the laws with
which spidroins, being secretory proteins, have to comply in order
to avoid membrane insertion and provide a road map to the production
of biomimetic silk fibers with improved mechanical properties.