Carbon dioxide concentrating mechanism in Chlamydomonas reinhardtii: inorganic carbon transport and CO2 recapture.

Many microalgae are capable of acclimating to CO(2) limited environments by operating a CO(2) concentrating mechanism (CCM), which is driven by various energy-coupled inorganic carbon (Ci; CO(2) and HCO(3)(-)) uptake systems. Chlamydomonas reinhardtii (hereafter, Chlamydomonas), a versatile genetic model organism, has been used for several decades to exemplify the active Ci transport in eukaryotic algae, but only recently have many molecular details behind these Ci uptake systems emerged. Recent advances in genetic and molecular approaches, combined with the genome sequencing of Chlamydomonas and several other eukaryotic algae have unraveled some unique characteristics associated with the Ci uptake mechanism and the Ci-recapture system in eukaryotic microalgae. Several good candidate genes for Ci transporters in Chlamydomonas have been identified, and a few specific gene products have been linked with the Ci uptake systems associated with the different acclimation states. This review will focus on the latest studies on characterization of functional components involved in the Ci uptake and the Ci-recapture in Chlamydomonas.