7zc1
Subtomogram averaging of Rubisco from Cyanobium carboxysome
Structural highlights
FunctionA5CKD0_9CYAN RuBisCO catalyzes two reactions: the carboxylation of D-ribulose 1,5-bisphosphate, the primary event in carbon dioxide fixation, as well as the oxidative fragmentation of the pentose substrate in the photorespiration process. Both reactions occur simultaneously and in competition at the same active site.[HAMAP-Rule:MF_01338] Publication Abstract from PubMedCarboxysomes 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. See AlsoReferences
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