EFFECTS OF VARYING LENGTHS OF DOUBLE-STRANDED-RNA ON BINDING AND ACTIVATION OF 2'-5'-OLIGOADENYLATE SYNTHETASE

We investigated the effects of varying the length of the double-strand ed (ds) RNA cofactor on activation of 2'-5'-oligoadenylate [2-5 (A)] s ynthetase, dsRNA of 40, 55, 67, 85, and 110 bp lengths were generated by in vitro transcription of complementary strands and annealing and t rimming of the single-stranded overhangs, The dsRNA molecules were rad iolabeled by polynucleotide kinase and purified by gel electrophoresis , Their abilities to bind to recombinant mouse 9-2 2-5 (A) synthetase, as monitored by electrophoretic mobility shift assays, were comparabl e, When used at a saturating concentration of 25 mu g/ml, all dsRNA mo lecules were equally effective in activating the enzyme, At a subsatur ating concentration, however, longer RNAs were better activators, At 1 00 nM concentration, there was a linear relationship between the lengt h of the dsRNA and its ability to activate 2-5 (A) synthetase.