also catalyzes RuBP reactivity with oxygen through photorespiration that results in a net loss of energy (1, 2). Thus, photosynthetic organisms such as cyanobacteria have evolved CO2-concentration mechanisms (CCM) to grow in high oxygen conditions. The CCM tilts the local gas concentration near rubisco towards CO2 rather than the O2 abundant in the atmosphere . In cyanobacteria, a bacterial microcompartment (BMC) (4) known as the carboxysome form the center of the CCM, encapsulating rubisco and carbonic anhydrase to create a locally high concentration of CO2 that enables efficient carbon fixation . )). In cryogenic electron microscopy (cryo-EM) atomic model, gray indicates CcmK hexamers, yellow CcmL pentamers; Ribulose 1,5-bisphosphate (RuBP) would enter the carboxysome, and bind to the rubisco enzyme. The RuBP can react either with CO2 or O2 that diffuses in from the cytosol, or with CO2 that is generated by carbonic anhydrase (CA) activity. Rubisco converts RuBP into 3-phosphoglycerate (3-PGA), which must traverse the carboxysome shell again to continue the Calvin-cycle.