title: Genes essential to sodium-dependent bicarbonate transport in cyanobacteria: function and phylogenetic analysis.
abstract: The cyanobacterium Synechocystis sp. strain PCC 6803 possesses two CO(2) uptake systems and two HCO(3)(-) transporters. We transformed a mutant impaired in CO(2) uptake and in cmpA-D encoding a HCO(3)(-)transporter with a transposon inactivation library, and we recovered mutants unable to take up HCO(3)(-) and grow in low CO(2) at pH 9.0. They are all tagged within slr1512 (designated sbtA). We show that SbtA-mediated transport is induced by low CO(2), requires Na(+), and plays the major role in HCO(3)(-) uptake in Synechocystis. Inactivation of slr1509 (homologous to ntpJ encoding a Na(+)/K(+)-translocating protein) abolished the ability of cells to grow at [Na(+)] higher than 100 mm and severely depressed the activity of the SbtA-mediated HCO(3)(-) transport. We propose that the SbtA-mediated HCO(3)(-) transport is driven by DeltamuNa(+) across the plasma membrane, which is disrupted by inactivating ntpJ. Phylogenetic analyses indicated that two types of sbtA exist in various cyanobacterial strains, all of which possess ntpJ. The sbtA gene is the first one identified as essential to Na(+)-dependent HCO(3)(-) transport in photosynthetic organisms and may play a crucial role in carbon acquisition when CO(2) supply is limited, or in Prochlorococcus strains that do not possess CO(2) uptake systems or Cmp-dependent HCO(3)(-) transport.
authors.affiliation: Bioscience Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Shibata
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Katoh
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Sonoda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohkawa
authors.forename: Masaya
authors.initials: M
authors.lastname: Shimoyama
authors.forename: Hideya
authors.initials: H
authors.lastname: Fukuzawa
authors.forename: Aaron
authors.initials: A
authors.lastname: Kaplan
authors.forename: Teruo
authors.initials: T
authors.lastname: Ogawa
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics; D001426:Bacterial Proteins; D001639:Bicarbonates / Q000378:metabolism*; D000458:Cyanobacteria / Q000235:genetics*; D005798:Genes, Bacterial; D020043:Genes, Essential; D017136:Ion Transport; D008565:Membrane Proteins / Q000235:genetics; D010802:Phylogeny; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001639:Bicarbonates; D008565:Membrane Proteins; D012964:Sodium; D000251:Adenosine Triphosphatases; C098928:NtpJ protein, bacteria