Figure 6.

Model of the β-Carboxysome Structure and Protein Stoichiometry.

(A) Diagram of an icosahedral carboxysome structure and organization of building components. The stoichiometry of each building component within the carboxysome and its variations in response to changes in CO₂ and light intensity are shown on the right (see also Table 1). *Rubisco content was estimated from RbcS stoichiometry based on the RbcL₈S₈ Rubisco structure. The majority of shell facets shown in light blue is tiled by the major shell protein CcmK2. The total abundance of CcmM58 and CcmM35 was estimated. The components RbcL, CcmK2, CcmO, and CcmP were not directly determined in this work and thus are not shown in this model.

(B) The carboxysome diameter is variable in response to changes in the CO₂ level and light intensity.