Expression of functional Na+/H+ antiporters of Helicobacter pylori in antiporter-deficient Escherichia coli mutants

FEBS Lett. 1999 Jan 22;443(1):11-6. doi: 10.1016/s0014-5793(98)01652-4.


An open reading frame with a sequence homologous to Escherichia coli Na+/H+ antiporter A (ENhaA) was found in the total genomic sequence of Helicobacter pylori, a pathogenic bacterium of gastric inflammation, and was named HNhaA. The primary sequences and the hydropathy profiles of ENhaA and HNhaA were very homologous except for one additional region found in HNhaA. This sequence has about 40 hydrophilic amino acid residues inserted at the position next to residue 235 of ENhaA which corresponds to residue 245 of HNhaA. HNhaA was expressed in E. coli mutants deficient in Na+/H+ antiporters and complemented the salt-sensitive phenotype of the mutants. Membrane vesicles prepared from these transformants of HNhaA using mutants deficient in the antiporters had the antiporter activities. Surprisingly, the antiporter activity in the transformant membranes was high at acidic and neutral pH, while ENhaA did not function at these pHs. A hydrophilic region around residue 235 in ENhaA and the additional hydrophilic region of about 40 residues in the same region found in HNhaA might be responsible for this difference in activity by acting as putative pH sensors.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Conserved Sequence
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Escherichia coli Proteins*
  • Genetic Complementation Test
  • Helicobacter pylori*
  • Lithium Chloride / pharmacology
  • Molecular Sequence Data
  • Open Reading Frames
  • Recombinant Proteins / biosynthesis
  • Sequence Homology, Amino Acid
  • Sodium Chloride / pharmacology
  • Sodium-Hydrogen Exchangers / genetics
  • Sodium-Hydrogen Exchangers / metabolism*
  • Species Specificity


  • Escherichia coli Proteins
  • NhaA protein, E coli
  • Recombinant Proteins
  • Sodium-Hydrogen Exchangers
  • Sodium Chloride
  • Lithium Chloride