On the role of intracellular potassium in protein synthesis

Abstract

1. 1. Mutants of Escherichia coli B that can be readily depleted of K + were used to study the role of K + in cell growth. When cells were depleted of K +, cell division and protein synthesis stopped, but ribonucleic acid synthesis continued. 2. 2. The effect of K + and Na + on protein synthesis was measured over a wide range of concentrations both in intact mutant cells and in the cell-free polyuridylic acid system. Na + was found to antagonize the action of K +. NH 4 + produced 2- to 4-fold more incorporation in the cell-free system than did K +. 3. 3. In the cell-free system, the rate of protein synthesis at low K + concentration was found to be limited by the transfer of amino acid from aminoacyl soluble ribonucleic acid to polypeptide. This result was consistent with the finding of unbalanced ribonucleic acid synthesis in K +-depleted mutant cells. 4. 4. The intracellular NH 4 + concentrations was found to be low, and appeared to be controlled at levels of 5–10 mM. 5. 5. The results suggest that decreased cell K + limits the rate of cell growth by a specific effect on protein synthesis.