Abstract:

Na+/H+ antiporter is the key factor in the salt-stress tolerance in organism. It can maintain normal
growth and metabolism of organism under high salt stress. Polymerase Chain Reaction (PCR) was performed to
clone a plasma membrane Na+/H+ antiporter genenhaA fromPseudomonas stutzeri. Sequence analysis showed
that the full length of the gene is 1167 bp, and it encodes a putative 388 amino acids polypeptide which
contained twelve putative transmembrane domains and conservative functional amino acids residues, such as
Asp-133, Asp-163, Asp-164, His-225, Gly-338. Nucleotide and amino acid sequence homology withnhaA
ofE. coli were 99% and 99.2%, respectively. The expression vector was constructed and thenhaA protein with
the molecular weight about 41 kD could also be detected inE.coli BL21 protein expression system. Plate
method and the growth curve analysis showed that the recombinant strains can survive under the salt stress of
800 mmol/L NaCl with increased salt tolerance. Results indicated that the cloned gene was a member ofnhaA
family, which they can antiport Na+, and further study in the salt-stress tolerance improvement ofnhaA could
base on these results. The gene has been accepted in GenBank by the accession number EU545468.