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bioRxiv · 10.1101/2024.04.25.591138

A two-component quasi-icosahedral protein nanocompartment with variable shell composition and irregular tiling

Dutcher, C. A.·Andreas, M. P.·Giessen, T. W.
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Abstract

Protein shells or capsids are a widespread form of compartmentalization in nature. Viruses use protein capsids to protect and transport their genomes while many cellular organisms use protein shells for varied metabolic purposes. These protein-based compartments often exhibit icosahedral symmetry and consist of a small number of structural components with defined roles. Encapsulins are a prevalent protein-based compartmentalization strategy in prokaryotes. All encapsulins studied thus far consist of a single shell protein that adopts the viral HK97-fold. Here, we report the characterization of a Family 2B two-component encapsulin from Streptomyces lydicus. We show the differential assembly behavior of the two shell components and demonstrate their ability to co-assemble into mixed shells with variable shell composition. We determined the structures of both shell proteins using cryo-electron microscopy. Using 3D-classification and crosslinking studies, we highlight the irregular tiling of mixed shells. Our work expands the known assembly modes of HK97-fold proteins and lays the foundation for future functional and engineering studies on two-component encapsulins.

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Dutcher, C. A., Andreas, M. P., Giessen, T. W.. 2024-04-26. A two-component quasi-icosahedral protein nanocompartment with variable shell composition and irregular tiling. https://doi.org/10.1101/2024.04.25.591138

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