Table 1

Relative abundances of α- and β-carboxysomal proteins in model carboxysomes from Synechococcus elongatus PCC 7942 (β-cyanobacteria), Prochlorococcus marinus MED4 (α-cyanobacteria), and Halothiobacillus neapolitanus C2 (Gammaproteobacteria)a

Protein categoryβ-Carboxysomesα-Carboxysomes
ProteinS. elongatus PCC 7942 (2% CO2)ProteinProchlorococcus MED4Halothiobacillus C2Structure
nnmStructurennmnnm
Shell proteinsCcmK2-46,8631,143Hexamer (147)CsoS1AB3,23253954090Hexamer (118)
CsoS1C002,970495Hexamer (119)
CcmO3,0751,025bTrimer (159)CsoS1D3813? (112, 120)?Trimer (120)
CcmP??Trimer (161)CsoS1E00? (112)?Trimer (112)
CcmL6012Pentamer (123)CsoS4AB60126012Pentamer (123)
CA enzymesCcaA1,058529Dimer (173)CsoSCA58298140.5Dimer (168)
CcmM-58d
Structural proteinsCcmN??Monomer? (143)CsoS2A00143329Monomer?
CcmM-582,177725Trimer (98)CsoS2B163c163186
CcmM-353,8293,829Monomer
RubisCO enzymeRbcL8,9601,120L8S4CcmM-354 (96)CbbL1,2161522,160270L8S8e
RbcS6,073CbbS1,2162,160
  • a The protein interactions, sizes, and putative structures of carboxysomes are illustrated in Fig. 7 and 8. Data for S. elongatus PCC 7942 are from references 96 and 159, those for P. marinus MED4 are from reference 112, and those for H. neapolitanus C2 are from reference 66. Other references for data are indicated in parentheses. n, gross number of proteins per carboxysome; nm, number of protein multimers per carboxysome.

  • b Calculated as the difference between the total number of hexagonal units required to cover beta-Cbx (2,168) (96) and the apparent number of CcmKx hexamers (1,143) (159).

  • c CsoS2 from MED4 is presumed to be equivalent to the unglycosylated form of CsoS2B from H. neapolitanus (112).

  • d CcmM is an active γ-CA enzyme in T. elongatus BP-1, and probably also in other species (138).

  • e From the crystal structure deposited in the Protein Data Bank (PDB entry 1SVD).