Protein Domain : Carboxysome assembly protein CcmM IPR017156

Type	Family
Description	This entry represents CcmM, which functions as a scaffold protein for the assembly of β-carboxysomes, initiates carboxysome assembly via its N-terminal domain binding to CcaA, CcmK and CcmL. Binds HCO3-, suggesting it may play a role in the activity or regulation of bicarbonate dehydration [ ].Aquatic photosynthetic organisms, like cyanobacteria, respond to low-CO(2) conditions by inducing a CO(2) concentrating mechanism (CCM) in the carboxysome. The CCM allows photosynthesis to proceed in CO2-limited aquatic environments [ ]. Carbonic anhydrases (CAs) and zinc metalloenzymes are important parts of the CCM. They catalyse the interconversion of CO(2) and HCO(3)(-) [ ]. The CCM components include at least four modes of active inorganic carbon uptake, including two bicarbonate transporters and two CO(2) uptake systems associated with the operation of specialised NDH-1 complexes. This results in the accumulation of HCO(3)(-) in the cytosol of the cell, which is subsequently used by the ribulose 1.5-bisphosphate carboxylase/oxygenase (RubisCO)-containing carboxysome protein micro-compartment within the cell to elevate CO(2) around RubisCO [ ]. Carboxysomal carbonic anhydrase is thought to dehydrate abundant cytosolic bicarbonate and provide RubisCO, sequestered within the carboxysome, with sufficiently high concentrations of CO(2) to permit its efficient fixation onto ribulose 1,5-bisphosphate [].
Short Name	CcmM