title: A Na+/H+ antiporter gene of the moderately halophilic bacterium Halobacillus dabanensis D-8T: cloning and molecular characterization.
abstract: A gene encoding a Na(+)/H(+) antiporter was cloned from a chromosomal DNA of Halobacillus dabanensis strain D-8(T) by functional complementation. Its presence enabled the antiporter-deficient Escherichia coli strain KNabc to survive in the presence of 0.2 M NaCl or 5 mM LiCl. The gene was sequenced and designated as nhaH. The deduced amino-acid sequence of NhaH consists of 403 residues with a calculated molecular mass of 43,481 Da, which was 54% identical and 76% similar to the NhaG Na(+)/H(+) antiporter of Bacillus subtilis. The hydropathy profile was characteristic of a membrane protein with 12 putative transmembrane domains. Everted membrane vesicles prepared from E. coli cells carrying nhaH exhibited Na(+)/H(+) as well as Li(+)/H(+) antiporter activity, which was pH-dependent with highest activities at pH 8.5-9.0 and at pH 8.5, respectively. Moreover, nhaH confers upon E. coli KNabc cells the ability to grow under alkaline conditions.
authors.affiliation: Department of Microbiology, College of Biological Sciences, China Agricultural University, and Key Laboratory of Agro-Microbial Resource and Application of Ministry of Agriculture, Beijing, China.
authors.forename: Li Fu
authors.initials: LF
authors.lastname: Yang
authors.forename: Ju Quan
authors.initials: JQ
authors.lastname: Jiang
authors.forename: Bai Suo
authors.initials: BS
authors.lastname: Zhao
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: De Qin
authors.initials: DQ
authors.lastname: Feng
authors.forename: Wei Dong
authors.initials: WD
authors.lastname: Lu
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Su Sheng
authors.initials: SS
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D001406:Bacillaceae / Q000145:classification / Q000235:genetics*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics* / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride