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Publication Abstract from PubMed

Carboxysomes are a family of bacterial microcompartments in cyanobacteria and chemoautotrophs. They encapsulate Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and carbonic anhydrase catalyzing carbon fixation inside a proteinaceous shell. How Rubisco complexes pack within the carboxysomes is unknown. Using cryo-electron tomography, we determine the distinct 3D organization of Rubisco inside two distant alpha-carboxysomes from a marine alpha-cyanobacterium Cyanobium sp. PCC 7001 where Rubiscos are organized in three concentric layers, and from a chemoautotrophic bacterium Halothiobacillus neapolitanus where they form intertwining spirals. We further resolve the structures of native Rubisco as well as its higher-order assembly at near-atomic resolutions by subtomogram averaging. The structures surprisingly reveal that the authentic intrinsically disordered linker protein CsoS2 interacts with Rubiscos in native carboxysomes but functions distinctively in the two alpha-carboxysomes. In contrast to the uniform Rubisco-CsoS2 association in the Cyanobium alpha-carboxysome, CsoS2 binds only to the Rubiscos close to the shell in the Halo alpha-carboxysome. Our findings provide critical knowledge of the assembly principles of alpha-carboxysomes, which may aid in the rational design and repurposing of carboxysome structures for new functions.

Structure and assembly of cargo Rubisco in two native alpha-carboxysomes.,Ni T, Sun Y, Burn W, Al-Hazeem MMJ, Zhu Y, Yu X, Liu LN, Zhang P Nat Commun. 2022 Jul 25;13(1):4299. doi: 10.1038/s41467-022-32004-w. PMID:35879301^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.