Role of Mg2+ in RNA splicing of T4 td intron

The splicing activity of T4 phage td intron RNA has been examined with various Mg2+ ions such as MgCl2, MgSO4 and magnesium acetate using various splicing conditions such as different incubation time and temperature, The maximum splicing of td intron RNA occurred at the concentration of 5 mM MgCl2. Raising the Mg2+ concentration up to 15 mM appeared to promote P2 deletion mutant to overcome the loss of some splicing activity, In both wild type and mutant, a complete hydrolysis of RNA occurred at 30 mM MgCl2. MgSO4 and magnesium acetate exhibited the rate and pattern of RNA splicing identical to MgCl2. The optimal splicing conditions involve the incubation of RNA with 5 mM MgCl2 at 58 degrees C for 15 min, The results suggest that Mg(2+)may play a key role in the catalytic mechanism of td intron RNA.