Markedly Different Effects of Monovalent Cations on the Efficiency of Gene Expression.

The effect of monovalent cations on a cell-free transcription-translation (TX-TL) system is examined using a luciferase assay. It is found that the potency for all ions analyzed here is in the order Rb+  > K+  > Cs+  > Na+  ≈ Li+  > (CH3 )4 N+ , where Rb+ is most efficient at promoting TX-TL and the ions of Li+ , Na+ , and (CH3 )4 N+ exhibit an inhibitory effect. Similar promotion/inhibition effects are observed for cell-free TL alone with an mRNA template.