7SNV

H. neapolitanus carboxysomal rubisco/CsoSCA-peptide (1-50)complex

Summary for 7SNV

• Entry DOI: 10.2210/pdb7snv/pdb
• Related: 7SMK
• EMDB information: 25201 25228
• Descriptor: Ribulose bisphosphate carboxylase large chain, Ribulose bisphosphate carboxylase small chain, Carboxysome shell carbonic anhydrase, ... (4 entities in total)
• Functional Keywords: rubisco, lyase, tim-barrel, complex
• Biological source: Halothiobacillus neapolitanus (strain ATCC 23641 / c2); More
• Total number of polymer chains: 3
• Total formula weight: 72388.80

Authors

Blikstad, C.,Dugan, E.,Laughlin, T.G.,Liu, M.,Shoemaker, S.,Remis, J.,Savage, D.F. (deposition date: 2021-10-28, release date: 2023-05-03, Last modification date: 2023-11-01)

Primary citation

Blikstad, C.,Dugan, E.J.,Laughlin, T.G.,Turnsek, J.B.,Liu, M.D.,Shoemaker, S.R.,Vogiatzi, N.,Remis, J.P.,Savage, D.F.
Identification of a carbonic anhydrase-Rubisco complex within the alpha-carboxysome.
Proc.Natl.Acad.Sci.USA, 120:e2308600120-e2308600120, 2023

PubMed Abstract: Carboxysomes are proteinaceous organelles that encapsulate key enzymes of CO fixation-Rubisco and carbonic anhydrase-and are the centerpiece of the bacterial CO concentrating mechanism (CCM). In the CCM, actively accumulated cytosolic bicarbonate diffuses into the carboxysome and is converted to CO by carbonic anhydrase, producing a high CO concentration near Rubisco and ensuring efficient carboxylation. Self-assembly of the α-carboxysome is orchestrated by the intrinsically disordered scaffolding protein, CsoS2, which interacts with both Rubisco and carboxysomal shell proteins, but it is unknown how the carbonic anhydrase, CsoSCA, is incorporated into the α-carboxysome. Here, we present the structural basis of carbonic anhydrase encapsulation into α-carboxysomes from . We find that CsoSCA interacts directly with Rubisco via an intrinsically disordered N-terminal domain. A 1.98 Å single-particle cryoelectron microscopy structure of Rubisco in complex with this peptide reveals that CsoSCA binding is predominantly mediated by a network of hydrogen bonds. CsoSCA's binding site overlaps with that of CsoS2, but the two proteins utilize substantially different motifs and modes of binding, revealing a plasticity of the Rubisco binding site. Our results advance the understanding of carboxysome biogenesis and highlight the importance of Rubisco, not only as an enzyme but also as a central hub for mediating assembly through protein interactions.

PubMed: 37862384
DOI: 10.1073/pnas.2308600120

Experimental method

ELECTRON MICROSCOPY (2.07 Å)