title: Cloning and characterization of a Na+/H+ antiporter gene of the moderately halophilic bacterium Halobacillus aidingensis AD-6T.
abstract: A gene encoding a Na(+)/H(+) antiporter was obtained from the genome of Halobacillus aidingensis AD-6(T), which was sequenced and designated as nhaH. The deduced amino acid sequence of the gene was 91% identical to the NhaH of H. dabanensis, and shared 54% identity with the NhaG of Bacillus subtilis. The cloned gene enable the Escherichia coli KNabc cell, which lack all of the major Na(+)/H(+) antiporters, to grow in medium containing 0.2 M NaCl or 10 mM LiCl. The nhaH gene was predicted to encode a 43.5 kDa protein (403 amino acid residues) with 11 putative transmembrane regions. Everted membrane vesicles prepared from E. coli KNabc cells carrying NhaH exhibited Na(+)/H(+) as well as Li(+)/H(+) antiporter activity, which was pH-dependent with the highest activity at pH 8.0, and no K(+)/H(+) antiporter activity was detected. The deletion of hydrophilic C-terminal amino acid residues showed that the short C-terminal tail was vital for Na(+)/H(+) antiporter activity.
authors.affiliation: Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, and Key Laboratory of Agro-Microbial Resource and Application, Ministry of Agriculture, Beijing 100094, PR China.
authors.forename: Ya Jie
authors.initials: YJ
authors.lastname: Zou
authors.forename: Li Fu
authors.initials: LF
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Su Sheng
authors.initials: SS
authors.lastname: Yang