1. Current models of the interactions of proteins within β-carboxysomes.
Current models of the interactions of proteins within β-carboxysomes. The CcmM-58 and CcmM-35 protein isoforms have independent roles, with the larger isoform (red) occupying the inner shell bicarbonate dehydration/RubisCO-organizing layer (inset) and recruiting the outer shell BMC layer via CcmN (blue), as well as recruiting the carboxysomal carbonic anhydrase CcaA (pink). Stoichiometric models suggest that the CcmM-35 isoform is probably localized predominantly to the interior RubisCO layers and interlinks adjacent RubisCO enzymes (green and tan) in three dimensions. Protein structure images were generated in Jmol (240), and protein threading was performed in Swiss-MODEL (241–243), using the following protein structures: CcmM-58 (PDB entry 3KWC) (138), CcmN (generated by threading the CcmN protein sequence onto PDB entry 3KWD chain A) (138), Rubisco (PDB entry 1RBL) (244), and CcaA (threaded onto PDB entry 1EKJG chain A) (245).
Benjamin D. Rae et al. Microbiol. Mol. Biol. Rev. 2013; doi: /MMBR