National Institutes of Health/National Institute of General Medical Sciences
P41GM103832
米国
National Institutes of Health/National Institute of General Medical Sciences
R01GM080139
米国
National Institutes of Health/National Institute of General Medical Sciences
R01GM037657
米国
Welch Foundation
H-0037
米国
Welch Foundation
Q1242
米国
引用
ジャーナル: J Mol Biol / 年: 2018 タイトル: Visualizing Individual RuBisCO and Its Assembly into Carboxysomes in Marine Cyanobacteria by Cryo-Electron Tomography. 著者: Wei Dai / Muyuan Chen / Christopher Myers / Steven J Ludtke / B Montgomery Pettitt / Jonathan A King / Michael F Schmid / Wah Chiu / 要旨: Cyanobacteria are photosynthetic organisms responsible for ~25% of the organic carbon fixation on earth. A key step in carbon fixation is catalyzed by ribulose bisphosphate carboxylase/oxygenase ...Cyanobacteria are photosynthetic organisms responsible for ~25% of the organic carbon fixation on earth. A key step in carbon fixation is catalyzed by ribulose bisphosphate carboxylase/oxygenase (RuBisCO), the most abundant enzyme in the biosphere. Applying Zernike phase-contrast electron cryo-tomography and automated annotation, we identified individual RuBisCO molecules and their assembly intermediates leading to the formation of carboxysomes inside Syn5 cyanophage infected cyanobacteria Synechococcus sp. WH8109 cells. Surprisingly, more RuBisCO molecules were found to be present as cytosolic free-standing complexes or clusters than as packaged assemblies inside carboxysomes. Cytosolic RuBisCO clusters and partially assembled carboxysomes identified in the cell tomograms support a concurrent assembly model involving both the protein shell and the enclosed RuBisCO. In mature carboxysomes, RuBisCO is neither randomly nor strictly icosahedrally packed within protein shells of variable sizes. A time-averaged molecular dynamics simulation showed a semi-liquid probability distribution of the RuBisCO in carboxysomes and correlated well with carboxysome subtomogram averages. Our structural observations reveal the various stages of RuBisCO assemblies, which could be important for understanding cellular function.