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bioRxiv · 10.1101/2023.06.24.546370

Intrinsically disordered CsoS2 acts as a general molecular thread for α-carboxysome shell assembly

Ni, T.·Jiang, Q.·Ng, P. C.·Shen, J.·Dou, H.·Zhu, Y.·Radecke, J.·Dykes, G. F.·Huang, F.·Liu, L.-N.·Zhang, P.
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Abstract

Carboxysomes are a paradigm of self-assembling proteinaceous organelles found in nature, offering compartmentalisation of enzymes and pathways to enhance carbon fixation. In -carboxysomes, the disordered linker protein CsoS2 plays an essential role in carboxysome assembly and Rubisco encapsulation. Its mechanism of action, however, is not fully understood. Here we synthetically engineered -carboxysome shells using minimal shell components and determined cryoEM structures of these to decipher the principle of shell assembly and encapsulation. The structures reveal that the intrinsically disordered CsoS2 C-terminus is well-structured and acts as a universal "molecular thread" stitching through multiple shell protein interfaces. We further uncovered in CsoS2 a remarkable highly conserved repetitive key interaction motif, [IV]TG, which is critical to the shell assembly and architecture. Our study provides a general mechanism for the CsoS2-govern carboxysome shell assembly and cargo encapsulation and further advances synthetic engineering of carboxysomes for diverse biotechnological applications.

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Ni, T., Jiang, Q., Ng, P. C., Shen, J., Dou, H., Zhu, Y., Radecke, J., Dykes, G. F., Huang, F., Liu, L.-N., Zhang, P.. 2023-06-24. Intrinsically disordered CsoS2 acts as a general molecular thread for α-carboxysome shell assembly. https://doi.org/10.1101/2023.06.24.546370

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