Cloning and sequencing of a K+ transport gene (trk A) from the marine bacterium Vibrio alginolyticus.

A gene has been cloned from the marine bacterium Vibrio alginolyticus that functionally complements a mutant strain of Escherichia coli, TK420, defective in K+ transport genes (kdpABC, trkD, trkA). The cloned Vibrio gene allowed TK420 to grow in a synthetic medium containing less than 10 mM K+ and concomitantly led to an increase in K+ uptake activity. The nucleotide sequence of the cloned fragment revealed an open reading frame, which encodes a protein with a predicted 458 amino acid sequence and molecular mass of 50,122 Da. This gene has 71% homology to trkA gene at the DNA level from E. coli and the deduced amino acid sequence is 79% identical with E. coli TrkA, implying that V. alginolyticus has a trkA-like gene as a component of K+ transport systems.