A Catalytic Nanoreactor Based on in Vivo Encapsulation of Multiple Enzymes in an Engineered Protein Nanocompartment

Bacterial protein compartments concentrate and sequester enzymes, thereby regulating biochemical reactions. Here, we generated a new functional nanocompartment in Escherichia coli by engineering the MS2 phage capsid protein to encapsulate multiple cargo proteins. Sequestration of multiple proteins in MS2-based capsids was achieved by SpyTag/SpyCatcher protein fusions that covalently crosslinked with the interior surface of the capsid. Further, the functional two-enzyme indigo biosynthetic pathway could be targeted to the engineered capsids, leading to a 60 % increase in indigo production in vivo. The enzyme-loaded particles could be purified in their active form and showed enhanced long-term stability in vitro (about 95 % activity after seven days) compared with free enzymes (about 5 % activity after seven days). In summary, this engineered in vivo encapsulation system provides a simple and versatile way for generating highly stable multi-enzyme nanoreactors for in vivo and in vitro applications.