Properties of the Na+/H+ antiporter in Vibrio parahaemolyticus
T Kuroda1, T Shimamoto, K Inaba
1Department of Microbiology, Faculty of Pharmaceutical Sciences, Okayama University.
Abstract:
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.
Related Concept Videos
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
ABC Transporters: Exporter
ABC Transporters: Importer
In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types:
ATP Driven Pumps III: V-type Pumps
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
Pore Transport and Ion-Pair Transport
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...
Regulation of Bacterial Virulence


