The Effect of Magnesium‐Ion Concentration on the Translation of Phage‐f2 RNA in a Cell‐Free System of Escherichia coli

The phage-f2 specific protein synthesis was studied in the cell-free system of Escherichia coli at 10.6–18.6 mM Mg2+. The products formed under the direction of f2 RNA between 12.6 mM and 18.6 mM Mg2+ were separated by polyacrylamide gel electrophoresis and found to correspond to phage-specific proteins, i. e. RNA synthetase and the coat protein. The rate of f2-RNA translation was optimal at 12.6 mM Mg2+. Lowering of Mg2+ concentration from the optimal value to 10.6 mM caused the lack of formation of complete RNA synthetase while the coat protein was still synthesised. This was due to a sharp decrease in rate of polypeptide-chain elongation, which led to incomplete translation of the longer gene. Our results indicate that, within the studied range of Mg2+ concentration, specific initiation of f2-RNA translation occurs even at 18.6 mM Mg2+.