title: The CO2 concentrating mechanism and photosynthetic carbon assimilation in limiting CO2 : how Chlamydomonas works against the gradient.
abstract: The CO2 concentrating mechanism (CCM) represents an effective strategy for carbon acquisition that enables microalgae to survive and proliferate when the CO2 concentration limits photosynthesis. The CCM improves photosynthetic performance by raising the CO2 concentration at the site of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), simultaneously enhancing carbon fixation and suppressing photorespiration. Active inorganic carbon (Ci) uptake, Rubisco sequestration and interconversion between different Ci species catalyzed by carbonic anhydrases (CAs) are key components in the CCM, and an array of molecular regulatory elements is present to facilitate the sensing of CO2 availability, to regulate the expression of the CCM and to coordinate interplay between photosynthetic carbon metabolism and other metabolic processes in response to limiting CO2 conditions. This review intends to integrate our current understanding of the eukaryotic algal CCM and its interaction with carbon assimilation, based largely on Chlamydomonas as a model, and to illustrate how Chlamydomonas acclimates to limiting CO2 conditions and how its CCM is regulated.
authors.affiliation: Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa, USA.
authors.forename: Yingjun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa, USA.
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Stessman
authors.affiliation: Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa, USA.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Spalding
mesh_terms: D000064:Acclimatization; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002696:Chlamydomonas / Q000502:physiology*; D002736:Chloroplasts / Q000378:metabolism / Q000648:ultrastructure; D003600:Cytosol / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D010788:Photosynthesis / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C425932:Cia5 protein, Chlamydomonas reinhardtii; D010940:Plant Proteins; D014157:Transcription Factors; D002245:Carbon Dioxide; D002244:Carbon; D002256:Carbonic Anhydrases
keywords: CO2 concentrating mechanism; Chlamydomonas; active CO2 uptake; bicarbonate transporter; inorganic carbon; limiting CO2; photosynthetic carbon assimilation