title: Polymerase chain reaction-based mutageneses identify key transporters belonging to multigene families involved in Na+ and pH homeostasis of Synechocystis sp. PCC 6803.
abstract: Primary ion pumps and antiporters exist as multigene families in the Synechocystis sp. PCC 6803 genome and show very strong homologies to those found in higher plants. The gene knock-outs of five putative Na+/H+ antiporters (slr1727, sll0273, sll0689, slr1595 and slr0415) and seven cation ATPases (sll1614, sll1920, slr0671-72, slr0822, slr1507-08-09, slr1728- 29 and slr1950) in the model cyanobacterium (http://www.kazusa.or.jp/cyano/cyano.html) were performed in this study relying on homologous recombination with mutagenenic fragments constructed using a fusion polymerase chain reaction (PCR) approach. The impacts of these gene knock-outs were evaluated in terms of Na+ and pH, and light-induced acidification and alkalization that are asso-ciated with inorganic carbon uptake. Two of the five putative antiporter mutants exhibit a characteristic interplay between the pH and Na+ dependence of growth, but only one of the antiporters appears to be necessary for high NaCl tolerance. On the other hand, the mutation of one of the two copper-trafficking ATPases produces a cell line that shows acute NaCl sensitivity. Additionally, disruptions of a putative Ca2+-ATPase and a gene cluster encoding a putative Na+-ATPase subunit also cause high NaCl sensitivity. The findings and possible mechanisms are discussed in relation to the potential roles of these transporters in Synechocystis sp. PCC 6803.
authors.affiliation: Department of Microbiology and Molecular Genetics, 307 Life Sciences East, Oklahoma State University, Stillwater, OK 74075, USA.
authors.forename: Hong-Liang
authors.initials: HL
authors.lastname: Wang
authors.forename: Bradley L
authors.initials: BL
authors.lastname: Postier
authors.forename: Robert L
authors.initials: RL
authors.lastname: Burnap
mesh_terms: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D001693:Biological Transport, Active / Q000502:physiology; D002244:Carbon / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology; D000458:Cyanobacteria / Q000235:genetics / Q000502:physiology*; D003573:Cytochrome b Group / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008027:Light; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D005810:Multigene Family; D016296:Mutagenesis; D010100:Oxygen / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017494:Proton Pumps / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D012964:Sodium / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; C090098:CtaA protein, bacteria; D003573:Cytochrome b Group; D008565:Membrane Proteins; D017494:Proton Pumps; D011994:Recombinant Proteins; D017923:Sodium-Hydrogen Exchangers; D002244:Carbon; D012964:Sodium; D010100:Oxygen