Erschienen in:
FEBS Letters, 527 (2002) 1-3, Seite 245-249
Sprache:
Englisch
DOI:
10.1016/s0014-5793(02)03244-1
ISSN:
0014-5793;
1873-3468
Entstehung:
Anmerkungen:
Beschreibung:
The genome of the hyperthermophilic archaeon Methanococcus jannaschii contains three Na+/H+ antiporter related genes Mj0057, Mj1521 and Mj1275. Comparative sequence alignments revealed that Mj0057 and Mj1521 belong to the NhaP family whereas Mj1275 is a member of the NapA family. The genes were cloned and expressed in the double mutant Escherichia coli strain Frag144 (ΔnhaA, ΔnhaB) to analyze their capability of mediating ΔpH driven Na+ flux in everted vesicles. From the tested clones only Mj0057 displayed Na+ (Li+)/H+ antiporter activity. The transport was pH dependent and occurred at pH 7.0 and below. At pH 6.0 the apparent Km values for Na+ and Li+ were approximately 10 and 2.5 mM, respectively.