carboxysome

Edge evidence

• carboxysome example of bacterial microcompartment rdfs:subClassOf

  The carboxysome is the archetypal bacterial microcompartment.

  • DOI:10.1038/nrmicro1913 Yeates et al. describe the carboxysome shell and its encapsulated enzymes.
• carboxysome contributes to carbon fixation RO:0002326

  Carboxysomal CO2 concentration accelerates RuBisCO-catalysed fixation.

  • DOI:10.1038/nrmicro.2018.10 Kerfeld et al. frame the carboxysome as a CO2-concentrating microcompartment supporting carbon fixation.
• carbon dioxide located in carboxysome biolink:located_in

  CO2 is concentrated within the carboxysome shell for fixation.

  • DOI:10.1038/nrmicro.2018.10 Kerfeld et al. review CO2 concentration inside the carboxysome.
• carboxysome shell prevents loss of carbon dioxide

  The carboxysome protein shell retains CO2, preventing its escape to the cytoplasm.

  • DOI:10.1038/nrmicro.2018.10 Kerfeld 2018: "The shell prevents loss of CO2 to the cytoplasm."
• carbonic anhydrase converts bicarbonate

  Carboxysomal carbonic anhydrase dehydrates imported bicarbonate to CO2.

  • DOI:10.1128/aem.01075-24 Wieschollek 2024: HCO3- entering carboxysomes is converted by CA to CO2; broad to bacterial CCMs with carboxysomes.
• carboxysome shell permits passage of bicarbonate

  Selective shell permeability allows HCO3- (and RuBP) to enter the carboxysome.

  • DOI:10.1093/plphys/kiae438 Cheng 2024: "the shell has selective permeability that permits HCO3- and RuBP passage."
• carboxysome shell limits influx of oxygen

  The carboxysome shell restricts O2 influx, reducing unproductive RuBisCO oxygenation.

  • DOI:10.1093/plphys/kiae438 Cheng 2024: shell permits HCO3-/RuBP passage "while limiting O2 influx."
• carbonic anhydrase elevates local concentration of carbon dioxide

  CA activity inside the carboxysome elevates local CO2 around RuBisCO.

  • DOI:10.1093/plphys/kiae438 Cheng 2024: "CA inside the carboxysome dehydrates HCO3- to CO2, elevating CO2 concentration around Rubisco."
• carbon dioxide enhances RuBisCO carboxylation

  Elevated CO2 around RuBisCO enhances carboxylation and reduces oxygenation.

  • DOI:10.1093/plphys/kiae438 Cheng 2024: elevated CO2 "enhances Rubisco carboxylation rates and reduces unproductive oxygenation."
• BMC-H/T/P shell proteins form carboxysome shell

  BMC-H hexamers, BMC-T pseudohexamers and BMC-P pentamers form the selectively permeable shell with central pores.

  • DOI:10.1038/nrmicro.2018.10 Kerfeld 2018: BMC-H/T/P proteins build the shell; a central pore "serves as a channel for metabolites"; generalized across BMCs including carboxysomes.