8THM

Beta carbonic anhydrase from the carboxysome of Cyanobium PCC 7001

Summary for 8THM

• Entry DOI: 10.2210/pdb8thm/pdb
• Descriptor: Carboxysome shell carbonic anhydrase, ZINC ION, GLYCEROL, ... (9 entities in total)
• Functional Keywords: beta-carbonic anhydrase, carboxysome, cyanobacteria, rubp activated, lyase, photosynthesis
• Biological source: Cyanobium sp. PCC 7001
• Total number of polymer chains: 6
• Total formula weight: 313010.34

Authors

Pulsford, S.B.,Jackson, C.J. (deposition date: 2023-07-17, release date: 2023-08-09, Last modification date: 2024-08-28)

Primary citation

Pulsford, S.B.,Outram, M.A.,Forster, B.,Rhodes, T.,Williams, S.J.,Badger, M.R.,Price, G.D.,Jackson, C.J.,Long, B.M.
Cyanobacterial alpha-carboxysome carbonic anhydrase is allosterically regulated by the Rubisco substrate RuBP.
Sci Adv, 10:eadk7283-eadk7283, 2024

PubMed Abstract: Cyanobacterial CO concentrating mechanisms (CCMs) sequester a globally consequential proportion of carbon into the biosphere. Proteinaceous microcompartments, called carboxysomes, play a critical role in CCM function, housing two enzymes to enhance CO fixation: carbonic anhydrase (CA) and Rubisco. Despite its importance, our current understanding of the carboxysomal CAs found in α-cyanobacteria, CsoSCA, remains limited, particularly regarding the regulation of its activity. Here, we present a structural and biochemical study of CsoSCA from the cyanobacterium sp. PCC7001. Our results show that the CsoSCA is allosterically activated by the Rubisco substrate ribulose-1,5-bisphosphate and forms a hexameric trimer of dimers. Comprehensive phylogenetic and mutational analyses are consistent with this regulation appearing exclusively in cyanobacterial α-carboxysome CAs. These findings clarify the biologically relevant oligomeric state of α-carboxysomal CAs and advance our understanding of the regulation of photosynthesis in this globally dominant lineage.

PubMed: 38728392
DOI: 10.1126/sciadv.adk7283

Experimental method

X-RAY DIFFRACTION (2.3 Å)