Cloning and sequencing of novel genes from Vibrio alginolyticus that support the growth of K+ uptake-deficient mutant of Escherichia coli

Novel genes that functionally complement the growth of K+ uptake-deficient mutant strain of Escherichia coli TK420 have been cloned from the marine bacterium Vibrio alginolyticus. The nucleotide sequence revealed three open reading frames. The second gene was homologous to proC gene and allowed the growth of proC-defective mutant strain of E. coli chi 342 in the absence of proline. The first and third genes, but not proC, were required for the growth of TK420 in a synthetic medium containing 10 mM K+ and 100 mM Na+. Since K+ uptake activity of TK420 was restored by the introduction of these genes, these two genes were considered to be directly related to K+ transport. Homologous genes were found in E. coli, but their functions have not been reported.