A Na+/H+ antiporter gene of the moderately halophilic bacterium Halobacillus dabanensis D-8T: cloning and molecular characterization.
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.
Yang
Li Fu
LF
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.
Jiang
Ju Quan
JQ
Zhao
Bai Suo
BS
Zhang
Bo
B
Feng
De Qin
DQ
Lu
Wei Dong
WD
Wang
Lei
L
Yang
Su Sheng
SS
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
D004269:DNA, Bacterial; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride