Dual Role of a Rubisco Activase in Metabolic Repair and Carboxysome Organization

Flecken, Mirkko; Wang, Huping; Popilka, L.; Hartl, F. Ulrich; Bracher, A.; Hayer‐Hartl, Manajit

doi:10.2139/ssrn.3631501

Cited by 3 publications

(4 citation statements)

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“…Our model is consistent with an exquisite structural snapshot of a prokaryotic carboxysome-associated green-type Rca hexamer bound to cyanobacterial Rubisco that has been communicated in a concurrent Biorxiv pre-print (54). In agreement with our findings, the study also reports that an N-terminal 9amino acid truncation of the tobacco Rubisco large subunit abolishes tobacco Rca function.…”

Section: Discussionsupporting

confidence: 90%

Rubisco activase requires residues in the large subunit N terminus to remodel inhibited plant Rubisco

Guo

Mueller‐Cajar

2020

Journal of Biological Chemistry

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The photosynthetic CO2 fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) forms dead-end inhibited complexes while binding multiple sugar phosphates, including its substrate ribulose 1,5-bisphosphate. Rubisco can be rescued from this inhibited form by molecular chaperones belonging to the ATPases associated with diverse cellular activities (AAA+ proteins) termed Rubisco activases (Rcas). The mechanism of green-type Rca found in higher plants has proved elusive, in part because until recently higher plant Rubiscos could not be expressed recombinantly. Identifying the interaction sites between Rubisco and Rca is critical to formulate mechanistic hypotheses. Towards that end here we purify and characterize a suite of 33 Arabidopsis Rubisco mutants for their ability to be activated by Rca. Mutation of 17 surface-exposed large subunit residues did not yield variants that were perturbed in their interaction with Rca. In contrast, we find that Rca activity is highly sensitive to truncations and mutations in the conserved N-terminus of the Rubisco large subunit. Large subunits lacking residues 1-4 are functional Rubiscos, but cannot be activated. Both T5A and T7A substitutions result in functional carboxylases that are poorly activated by Rca, indicating the side chains of these residues form a critical interaction with the chaperone. Many other AAA+ proteins function by threading macromolecules through a central pore of a disc-shaped hexamer. Our results are consistent with a model where Rca transiently threads the Rubisco large subunit N-terminus through the axial pore of the AAA+ hexamer.

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Section: Discussionsupporting

confidence: 90%

Rubisco activase requires residues in the large subunit N terminus to remodel inhibited plant Rubisco

Guo

Mueller‐Cajar

2020

Journal of Biological Chemistry

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“…Helix 9 elements of two adjacent Rca subunits can be placed in proximity to two RbcL βC-βD loops that are located on two adjacent dimers ( The model is consistent with an exquisite structural snapshot of a prokaryotic carboxysome-associated green-type Rca hexamer bound to cyanobacterial Rubisco that has been communicated in a concurrent Biorxiv pre-print (46). In agreement with our findings, the study also reports that an N-terminal 9amino acid truncation of the tobacco Rubisco large subunit abolishes tobacco Rca function.…”

Section: Discussionsupporting

confidence: 53%

Rubisco activase remodels plant Rubisco via the large subunit N-terminus

Mueller‐Cajar

2020

Preprint

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The photosynthetic CO2 fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) forms inhibited complexes with multiple sugar phosphates, including its substrate ribulose 1,5-bisphosphate. At least three classes of ATPases associated with diverse cellular activities (AAA+ proteins) termed Rubisco activases (Rcas) have evolved to remodel inhibited Rubisco complexes. The mechanism of green-type Rca found in higher plants has proved elusive, because until recently higher plant Rubiscos could not be expressed recombinantly. Towards identifying interaction sites between Rubisco and Rca, here we produce and characterize a suite of 33 Arabidopsis Rubisco mutants for their ability to be activated by Rca. We find that Rca activity is highly sensitive to truncations and mutations in the conserved N-terminus of the Rubisco large subunit. Both T5A and T7A substitutions cannot be activated by Rca, but present with increased carboxylation velocities. Our results are consistent with a model where Rca functions by transiently threading the Rubisco large subunit N-terminus through the axial pore of the AAA+ hexamer.

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“…With regard to activases, recent studies revealed and characterized a novel βcarboxysomal Rubisco activase (Flecken et al, 2020;Lechno-Yossef et al, 2020).…”

Section: Carboxysomal Rubisco Chaperones and Activasesmentioning

confidence: 99%

“…This domain likely serves as an additional interaction site between the carboxysomal activase and Rubisco (Flecken et al, 2020).…”

Section: Carboxysomal Rubisco Chaperones and Activasesmentioning

confidence: 99%

Towards the in vitro reconstitution of proteobacterial carboxysomes

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Dual Role of a Rubisco Activase in Metabolic Repair and Carboxysome Organization

Cited by 3 publications

References 0 publications

Rubisco activase requires residues in the large subunit N terminus to remodel inhibited plant Rubisco

Rubisco activase requires residues in the large subunit N terminus to remodel inhibited plant Rubisco

Rubisco activase remodels plant Rubisco via the large subunit N-terminus

Towards the in vitro reconstitution of proteobacterial carboxysomes

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