Poly 2'-O-ethylcytidylate, an inhibitor and poor template for AMV reverse transcriptase

Abstract

Poly(2'-O-ethylcytidylate) is a poor template-primer for purified avian myeloblastosis virus reverse transcriptase; the relative activities of the template-primers poly(C)-oligo(dG), poly(Cm)-oligo(dG) and poly(Ce)-oligo(dG) are 23:16:1. A mixture of poly(Ce) and poly(dI) is inactive as template-primer, in agreement with the observed inability of these to form a helical complex. By contrast the inactivity of poly(Ce)-poly(I) is shown to be due to the influence of the 2'-O-ethyl residue. Poly(Ce) inhibits poly(A)-oligo(dT)-directed polymerase activity, with Ki = 3 muM, but marked inhibition with poly(A)-poly(dT) occurs only at low concentrations of the latter. Poly(Ce) did not inhibit template-primer activity of poly(C)-poly(dI) and poly(dC)-poly(dI). Qualitative physico-chemical studies show only partial complex formation between oligo(dG) and poly(C) and its 2'-O-alkyl analogues. This is discussed in relation to the widespread use of poly(C)-oligo(dG) as the template-primer for reverse transcriptase.