The Plasticity of Molecular Interactions Governs Bacterial Microcompartment Shell Assembly.

Bacterial microcompartments (BMCs) are composed of an enzymatic core encapsulated by a selectively permeable protein shell that enhances catalytic efficiency. Many pathogenic bacteria derive competitive advantages from their BMC-based catabolism, implicating BMCs as drug targets. BMC shells are of interest for bioengineering due to their diverse and selective permeability properties and because they self-assemble. A complete understanding of shell composition and organization is a prerequisite for biotechnological applications. Here, we report the cryoelectron microscopy structure of a BMC shell at 3.0-Å resolution, using an image-processing strategy that allowed us to determine the previously uncharacterized structural details of the interactions formed by the BMC-TS and BMC-TD shell subunits in the context of the assembled shell. We found unexpected structural plasticity among these interactions, resulting in distinct shell populations assembled from varying numbers of the BMC-TS and BMC-TD subunits. We discuss the implications of these findings on shell assembly and function. • 3.0-Å resolution cryo-EM structure of the H. ochraceum (HO) microcompartment shell • Asymmetric data processing strategy resolves complete blueprint for shell assembly • Structure of shell-embedded BMC-TS shell subunit reveals its specific interactions • Insights into structural and compositional variability of the HO BMC shell Greber et al. use high-resolution cryoelectron microscopy to reveal the structural plasticity in a bacterial microcompartment shell and the complete blueprint for its assembly. [ABSTRACT FROM AUTHOR]