Tetracycline resistance element of pBR322 mediates potassium transport

The tetracycline resistance element of plasmid pBR322 partially complements the potassium transport defect of Escherichia coli K-12 mutants having markedly impaired K+ transport. The plasmid increases K+ transport. The Tn10 element does not result in increased transport, demonstrating that the effect is not general for elements that increase resistance to tetracycline.