Heterologous Assembly of Pleomorphic Bacterial Microcompartment Shell Architectures Spanning the Nano- to Microscale.

Many bacteria use protein-based organelles known as bacterial microcompartments (BMCs) to organize and sequester sequential enzymatic reactions. Regardless of their specialized metabolic function, all BMCs are delimited by a shell made of multiple structurally redundant, yet functionally diverse, hexameric (BMC-H), pseudohexameric/trimeric (BMC-T), or pentameric (BMC-P) shell protein paralogs. When expressed without their native cargo, shell proteins have been shown to self-assemble into 2D sheets, open-ended nanotubes and closed shells of ∼40 nm diameter that are being developed as scaffolds and nanocontainers for applications in biotechnology. Here by leveraging a strategy for affinity-based purification we demonstrate that a wide range of empty synthetic shells, many differing in end cap structures, can be derived from a glycyl radical enzyme-associated microcompartment (GRM). The range of pleomorphic shells observed, which span ∼2 orders of magnitude in size from ∼25 nm to ∼1.8 μm, reveals the remarkable plasticity of BMC-based biomaterials. In addition, we observe new capped nanotube and nanocone morphologies that are consistent with a multi-component geometric model in which architectural principles are shared among asymmetric carbon, viral protein, and BMC-based structures. This article is protected by copyright. All rights reserved.