Encapsidic production and isolation of degradation-prone polypeptides

Degradation during production and delivery is a significant bottleneck in developing biomolecular therapies. Here, we show that encapsulation in protein cages formed by engineered variants of a cage-forming lumazine synthase establishes an effective route for microbial production and isolation of otherwise difficult-to-express, degradation-prone polypeptides. In this system, genetic fusion to a cage component protomer ensures efficient guest packaging while being produced in host bacterial cells. Meanwhile, the controlled opening outside the cellular context allows facile isolation of cargo via sequence-specific protease cleavage. Furthermore, modular patchwork assembly avoids guest overloading, preventing unwanted incomplete cage assembly and the formation of insoluble aggregates. The general applicability of our "encapsidic" production approach was demonstrated by the efficient production of six intrinsically disordered polypeptides that have proven therapeutic potentials.