A basal carbon concentrating mechanism in plants?

ZABALETA EDUARDO; MARTÍN VICTORIA; BRAUN HANS-PETER

PLANT SCIENCE

ELSEVIER IRELAND LTD

Año: 2012 vol. 187 p. 97 - 104

0168-9452

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 describedin great detail. These systems are believed to have evolved several times as mechanisms that acclimateorganisms to unfavourable growth conditions. Based on recent experimental evidence we proposethe occurrence of another more general CCM system present in all plants. This basal CCM (bCCM) issupposed to be composed of mitochondrial carbonic anhydrases (B-type carbonic anhydrase and theG-type carbonic anhydrase domain of the mitochondrial NADH dehydrogenase complex) and probablyfurther unknown components. The bCCM is proposed to reduce leakage of CO2 from plant cells and allowefficient recycling of mitochondrial CO2 for carbon fixation in chloroplasts.