The Na+ and K+ transport deficiency of an E. coli mutant lacking the NhaA and NhaB proteins is apparent and caused by impaired osmoregulation.
Cells of the E. coli mutant EP432, which lacks the two Na+/H+ antiporters, NhaA and NhaB, have been reported to have an impaired sodium transport activity (Harel-Bronstein et al. (1995) J. Biol. Chem. 270, 3816-3822). Here we report that active transport of Na+ in EP432 cells can be restored to wild-type levels, either by a high K+ concentration or by an increase in the medium osmolarity. We suggest that this mutant is primarily deficient in osmoregulation rather than in cation transport per se.
Verkhovskaya
M L
ML
Department of Medical Chemistry, Institute of Biomedical Sciences, University of Helsinki, Finland. marina.verkhovskaya@helsinki.fi
Barquera
B
B
Verkhovsky
M I
MI
Wikström
M
M
D001426:Bacterial Proteins; D002455:Cell Division; D003593:Cytoplasm / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D017136:Ion Transport; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D014882:Water-Electrolyte Balance
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C102839:NhaA protein, E coli; C491047:NhaB protein, E coli; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium; D011188:Potassium