Related Papers
bioRxiv (Cold Spring Harbor Laboratory)
Dual Role of a Rubisco Activase in Metabolic Repair and Carboxysome Organization
2020 •
Manajit Hayer-Hartl
Molecular cell
Mechanism of Enzyme Repair by the AAA(+) Chaperone Rubisco Activase
2017 •
Javaid Bhat
How AAA+ chaperones conformationally remodel specific target proteins in an ATP-dependent manner is not well understood. Here, we investigated the mechanism of the AAA+ protein Rubisco activase (Rca) in metabolic repair of the photosynthetic enzyme Rubisco, a complex of eight large (RbcL) and eight small (RbcS) subunits containing eight catalytic sites. Rubisco is prone to inhibition by tight-binding sugar phosphates, whose removal is catalyzed by Rca. We engineered a stable Rca hexamer ring and analyzed its functional interaction with Rubisco. Hydrogen/deuterium exchange and chemical crosslinking showed that Rca structurally destabilizes elements of the Rubisco active site with remarkable selectivity. Cryo-electron microscopy revealed that Rca docks onto Rubisco over one active site at a time, positioning the C-terminal strand of RbcL, which stabilizes the catalytic center, for access to the Rca hexamer pore. The pulling force of Rca is fine-tuned to avoid global destabilization an...
Frontiers in molecular biosciences
Rubisco Activases: AAA+ Chaperones Adapted to Enzyme Repair
2017 •
Manajit Hayer-Hartl
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), the key enzyme of the Calvin-Benson-Bassham cycle of photosynthesis, requires conformational repair by Rubisco activase for efficient function. Rubisco mediates the fixation of atmospheric CO2 by catalyzing the carboxylation of the five-carbon sugar ribulose-1,5-bisphosphate (RuBP). It is a remarkably inefficient enzyme, and efforts to increase crop yields by bioengineering Rubisco remain unsuccessful. This is due in part to the complex cellular machinery required for Rubisco biogenesis and metabolic maintenance. To function, Rubisco must undergo an activation process that involves carboxylation of an active site lysine by a non-substrate CO2 molecule and binding of a Mg(2+) ion. Premature binding of the substrate RuBP results in an inactive enzyme. Moreover, Rubisco can also be inhibited by a range of sugar phosphates, some of which are "misfire" products of its multistep catalytic reaction. The release of the inh...
Proceedings of the National Academy of Sciences
Rubisco accumulation factor 1 (Raf1) plays essential roles in mediating Rubisco assembly and carboxysome biogenesis
2020 •
Luning Liu
Significance Cyanobacteria are keystone organisms in global carbon fixation. Their great carbon-assimilation capability arises from a specialized virus-like protein organelle, the carboxysome, which comprises hundreds of proteins that form a shell to encapsulate the CO 2 -fixing enzymes Rubisco and carbonic anhydrase. How do these proteins self-assemble to construct the defined architecture? Here we explore the significance of one assembly factor, Raf1, in Rubisco assembly and carboxysome formation. We show that Raf1 mediates Rubisco assembly; without Raf1, carboxysome proteins are prone to form intermediate assemblies and small carboxysome-like structures rather than intact carboxysomes. Our results suggest a model of the Raf1-mediated biogenesis of carboxysomes and provide advanced knowledge of carboxysome assembly and function, informing synthetic engineering of functional CO 2 -fixing organelles for biotechnological applications.
Protein Science
From chaperonins to Rubisco assembly and metabolic repair
2017 •
Manajit Hayer-Hartl
Plant Physiology
Roles of RbcX in Carboxysome Biosynthesis in the Cyanobacterium Synechococcus elongatus PCC7942
Luning Liu
bioRxiv (Cold Spring Harbor Laboratory)
Cyanobacterial α-carboxysome carbonic anhydrase is allosterically regulated by the Rubisco substrate RuBP
2023 •
Britta Förster
Nature Communications
Structure and assembly of cargo Rubisco in two native α-carboxysomes
Luning Liu
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 α-carboxysomes from a marine α-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 α-carboxysomes. In c...
F1000 - Post-publication peer review of the biomedical literature
F1000Prime recommendation of The small RbcS-like domains of the β-carboxysome structural protein, CcmM, bind RubisCO at a site distinct from that binding the RbcS subunit
2019 •
Norma Allewell
Tales of Two α-Carboxysomes: the Structure and Assembly of Cargo Rubisco
2022 •
Luning Liu
Carboxysomes are a family of bacterial microcompartments in cyanobacteria and chemoautotrophs. It encapsulates carbonic anhydrase and Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalysing carbon fixation inside a proteinaceous shell. How Rubisco packs into the carboxysomes is unknown. Using cryo-electron tomography and subtomogram averaging, we present 3D organization of Rubisco inside two types of native α-carboxysomes from a marine α-cyanobacterium Cyanobium sp. PCC 7001 and a chemoautotrophic bacterium Halothiobacillus neapolitanus. We determined the structures of Rubiscos within native Halothiobacillus and Cyanobium carboxysomes at 3.3 Å and 3.8 Å resolution respectively and further identified an associated CsoS2 segment. Interestingly, CsoS2 is only associated with a sub-population of Rubiscos that are close to the shell in Halothiobacillus, but with all Rubiscos throughout Cyanobium carboxysome. Moreover, Rubiscos in Cyanobium carboxysomes are organized in three...
