5.2 Improved biotemplate production yields
VLPs frequently form insoluble aggregates when expressed in non-native
hosts that are unsuitable for biotemplating processes [87]. To
increase the yield of usable VLP biotemplates, the solubility of
heterologous CP must be enhanced. There are many ways to increase
protein solubility [88]; however, increasing CP solubility for VLPs
production is challenging as one of the drivers of protein insolubility,
strong hydrophobic interactions, is also the driving force for virion
and VLP assembly. However, machine learning algorithms have begun to
identify the design rules for soluble VLP CP design without disrupting
VLP self-assembly based on hydrophobicity scales [89]. An early
report with these tools counterintuitively suggests that CP solubility
may be highly correlated with arginine content in some VLPs, despite its
negative correlation with solubility of short chain variable fragments.
Arginine reduces many hydrophobic protein-protein interactions while
interacting favorably with other amino acids to reduce random
aggregation. However, these tools have yet to be applied to forward
engineer novel VLP CPs.