title: An ABC transporter is required for alkaline stress and potassium transport regulation in Sinorhizobium meliloti.
abstract: To understand the mechanisms of high-pH-induced protection in Sinorhizobium meliloti, a cDNA-amplified fragment length polymorphism analysis of S. meliloti cells grown in minimal medium under alkali stress was undertaken. This revealed that the first four genes of a seven-gene cluster encode the characteristic components of a putative sugar ATP-binding cassette (ABC) transporter. A functional study suggested that this putative sugar ABC transporter might play a role in potassium transport regulation, which we therefore designated supABCD. The transcription of three potassium uptake genes, trkH, kdpA and kup1, in S. meliloti is significantly attenuated in the supA mutant in the presence of potassium. The supA mutant was unable to grow at elevated levels of potassium. The expression of supA, as determined by beta-galactosidase activity, was shown to be induced by potassium but not by sodium.
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Science, China Agricultural University, Beijing, China.
authors.forename: Dong Xu
authors.initials: DX
authors.lastname: Lin
authors.forename: Hui
authors.initials: H
authors.lastname: Tang
authors.forename: En Tao
authors.initials: ET
authors.lastname: Wang
authors.forename: Wen Xin
authors.initials: WX
authors.lastname: Chen
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D003470:Culture Media; D018076:DNA, Complementary / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D018869:Heat-Shock Response; D006863:Hydrogen-Ion Concentration; D005810:Multigene Family; D009154:Mutation; D012150:Polymorphism, Restriction Fragment Length; D011188:Potassium / Q000378:metabolism*; D016962:Sinorhizobium meliloti / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D003470:Culture Media; D018076:DNA, Complementary; D011188:Potassium