For the first time, a recombinant surfactant protein has been
produced and assembled into higher ordered structures which could be used to
make membranes. Using recombinant amphiphilic proteins to self-assemble suprastructures
allows precise control over surfactant chemistry and facile incorporation of
biological functionality. From the perspective of polymer chemistry, this is
akin to making a polymer in which the identify of every monomer in the chain is
set with precision. Multiple variations of the sunflower seed protein oleosin
were produced in bacterial cell culture, as illustrated in the upper right. By
controlling solution composition and protein chemistry, the recombinant
proteins were observed to self-assemble into sheets, fibers, and vesicles.
Oleosin variants were made
with standard processing techniques from recombinant biotechnology. A. Phase
behavior of a series of oleosin mutants, with 65
residues in the hydrophobic core and various lengths of the hydrophilic
fraction, that assemble into various structures in solutions of different
osmotic strength including B. fibers, C. sheets, and D. vesicles (Vargo et al. 2012), all
characterized by cryo-TE.
