Cation transport alteration associated with plasmid-determined resistance to cadmium in Staphylococcus aureus

Abstract

Plasmid-determined resistance to cadmium has only been found with plasmids from Staphylococcus aureus. Resistance to cadmium was associated with a lower accumulation of Cd(2+) ions by the plasmid-bearing resistant cells. Cadmium accumulation by susceptible cells was energy dependent and had those characteristics usually associated with a transmembrane active transport system. There was a specific interrelationship between cadmium accumulation and manganese accumulation and retention. Cd(2+) inhibited the uptake of Mn(2+) and accelerated the loss of intracellular Mn(2+) by the susceptible cells, but was without effect on Mn(2+) transport in resistant S. aureus cells. Under similar conditions, there was no differential effect of Cd(2+) on Mg(2+), Zn(2+), Co(2+), Ni(2+), or Rb(+) accumulation or exchange between the susceptible and the resistant strains.