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submitted on 01.02.2018 and posted on 01.02.2018by Noor H. Dashti, Rufika S. Abidin, Frank Sainsbury
Bioinspired self-sorting and self-assembling
systems using engineered versions of natural protein cages have been developed
for biocatalysis and therapeutic delivery. The packaging and intracellular delivery
of guest proteins is of particular interest for both in vitro and in vivo cell
engineering. However, there is a lack of platforms in bionanotechnology that
combine programmable guest protein encapsidation with efficient intracellular
uptake. We report a minimal peptide anchor for in vivo self-sorting of cargo-linked capsomeres of the Murine
polyomavirus (MPyV) major coat protein that enables controlled encapsidation of
guest proteins by in vitro
self-assembly. Using Förster resonance energy transfer (FRET) we demonstrate
the flexibility in this system to support co-encapsidation of multiple proteins.
Complementing these ensemble measurements with single particle analysis by
super-resolution microscopy shows that the stochastic nature of
co-encapsidation is an overriding principle. This has implications for the
design and deployment of both native and engineered self-sorting encapsulation
systems and for the assembly of infectious virions. Taking advantage of the
encoded affinity for sialic acids ubiquitously displayed on the surface of
mammalian cells, we demonstrate the ability of self-assembled MPyV virus-like
particles to mediate efficient delivery of guest proteins to the cytosol of
primary human cells. This platform for programmable co-encapsidation and
efficient cytosolic delivery of complementary biomolecules therefore has
enormous potential in cell engineering.