title: The complete genome of a cyanobacterium from a soda lake reveals the presence of the components of CO2-concentrating mechanism.
abstract: At present geological epoch, the carbon concentrating mechanism (CCM) of cyanobacteria represents the obligatory tool for adaptation to low content of CO2in the atmosphere and for the maintenance of sufficient photosynthetic activity. Functional CCM was found in modern cyanobacteria from different ecological niches. However, the presence of such mechanism in species that inhabit soda lakes is not obvious due to high content of inorganic carbon (Ci) in the environment. Here we analyze CCM components that have been identified by sequencing of the whole genome of the alkaliphilic cyanobacterium Microcoleus sp. IPPAS B-353. The composition of the CCM components of Microcoleus is similar to that of 'model' β-cyanobacteria, freshwater and marine Synechococcus or Synechocystis spp. However, CahB1 protein of Microcoleus, which is the homolog of CcaA, the carboxysomal β-type carbonic anhydrase (CA) of β-cyanobacteria, appeared to be the only active CA located in cell envelopes. The conservative regions of CcmM, CahG (a homolog of archeal γ-CAs, Cam/CamH), and ChpX of Microcoleus possess single amino acid substitutions that may cause a lack of CA activities. Unlike model cyanobacteria, Microcoleus induces only one BicA-type bicarbonate transporter in response to Cilimitation. The differences in the appearance of CCM components and in their characteristics between alkaliphilic Microcoleus and freshwater or marine cyanobacteria are described. The possible reasons for the maintenance of CCM components in cyanobacteria, which permanently live at high concentrations of Ciin soda lakes, are discussed.
authors.affiliation: Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya street 35, Moscow, Russia, 127276. ivlaanov@mail.ru.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Kupriyanova
authors.affiliation: Department of Biological Sciences, Chungnam National University, Daejeon, 305-764, Korea.
authors.forename: Sung Mi
authors.initials: SM
authors.lastname: Cho
authors.affiliation: Department of Biological Sciences, Chungnam National University, Daejeon, 305-764, Korea.
authors.forename: Youn-Il
authors.initials: YI
authors.lastname: Park
authors.affiliation: Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya street 35, Moscow, Russia, 127276.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Pronina
authors.affiliation: Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya street 35, Moscow, Russia, 127276.
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Los
mesh_terms: D015153:Blotting, Western; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism; D000458:Cyanobacteria / Q000235:genetics* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005798:Genes, Bacterial / Q000235:genetics; D016680:Genome, Bacterial / Q000235:genetics*; D012329:RNA, Bacterial / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D012329:RNA, Bacterial; D002245:Carbon Dioxide; D002244:Carbon; D002256:Carbonic Anhydrases
keywords: CO2 concentrating mechanism (CCM); Cyanobacteria; Genome; Soda lakes