Spectinomycin inhibits the self-splicing of the group 1 intron RNA

Effects of the aminoglycoside spectinomycin on the self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td) have been inves tigated. The kinetic analysis demonstrated that spectinomycin acts as a mix ed noncompetitive inhibitor for the td intron RNA with a K-i of 7.2 mM. Inc reasing the spectinomycin concentration raised the K-m values with the corr esponding decrease of V-max and k(cat) values. The specificity of the splic ing inhibition by spectinomycin is due to changes in both K-m and k(cat). T he splicing inhibition by spectinomycin is dependent on pH changes and Mg2 concentration, indicating electrostatic interactions with the intron RNA. It has been proposed that the key structural features in spectinomycin resp onsible for the inhibition of splicing may be the hydroxyl groups on the an tibiotic. (C) 2000 Academic Press.