title: A basal carbon concentrating mechanism in plants?
abstract: Many photosynthetic organisms have developed inorganic carbon (Ci) concentrating mechanisms (CCMs) that increase the CO₂ concentration within the vicinity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). Several CCMs, such as four carbon (C4) and crassulacean acid metabolism (CAM), bicarbonate accumulation systems and capsular structures around RubisCO have been described in great detail. These systems are believed to have evolved several times as mechanisms that acclimate organisms to unfavourable growth conditions. Based on recent experimental evidence we propose the occurrence of another more general CCM system present in all plants. This basal CCM (bCCM) is supposed to be composed of mitochondrial carbonic anhydrases (a β-type carbonic anhydrase and the γ-type carbonic anhydrase domain of the mitochondrial NADH dehydrogenase complex) and probably further unknown components. The bCCM is proposed to reduce leakage of CO₂ from plant cells and allow efficient recycling of mitochondrial CO₂ for carbon fixation in chloroplasts.
authors.affiliation: Instituto de Investigaciones Biológicas IIB-CONICET-UNMdP, Funes 3250 3er nivel 7600 Mar del Plata, Argentina. ezabalet@mdp.edu.ar
authors.forename: Eduardo
authors.initials: E
authors.lastname: Zabaleta
authors.forename: M Victoria
authors.initials: MV
authors.lastname: Martin
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Braun
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D008954:Models, Biological; D009245:NADH Dehydrogenase / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D059828:Plant Cells / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D009245:NADH Dehydrogenase; D012273:Ribulose-Bisphosphate Carboxylase; D002256:Carbonic Anhydrases