Properties of the Na+/H+ antiporter in Vibrio parahaemolyticus.
The properties of the Na+/H+ antiporter in Vibrio parahaemolyticus, a slightly halophilic bacterium, were investigated using everted membrane vesicles. It appears that at least two Na+/H+ antiporters are present, one that is pH-dependent and one that is pH-independent. These two antiporters appear to correspond to the NhaA and NhaB antiporters of Escherichia coli, respectively. It seems that amiloride strongly inhibits the pH-dependent antiporter. Na+ is the best substrate for both of the two V. parahaemolyticus antiporters. Li+ is a poorer substrate and K+ is not a substrate. No K+/H+ antiport activity was detected in membrane vesicles of this organism. The Na+(Li+)/H+ antiport activity greatly increased with an increase in pH of the assay medium. pH did not affect the Km value of the Na+/H+ antiport, but it did increase the Vmax.
Kuroda
T
T
Department of Microbiology, Faculty of Pharmaceutical Sciences, Okayama University.
Shimamoto
T
T
Inaba
K
K
Kayahara
T
T
Tsuda
M
M
Tsuchiya
T
T
D006863:Hydrogen-Ion Concentration; D017923:Sodium-Hydrogen Exchangers / Q000032:analysis*; D014736:Vibrio parahaemolyticus / Q000737:chemistry*
D017923:Sodium-Hydrogen Exchangers