A study of antitemplate inhibition of mammalian, bacterial and viral DNA polymerases by 2- and 2'-substituted derivatives of polyadenylic acid.

In the present study, effects of various 2- and 2'-substituted polyadenylic acid analogs on eukaryotic, bacterial and viral DNA polymerases were investigated. The polymer containing 2'-deoxy-2'fluoroadenosine, (dAfl)n, showed a concentration dependent stimulation of (rA)n . (dT)12-catalyzed reverse transcriptase reaction from Rauscher Leukemia Virus (RLV). A similar stimulation of the (rA)n . (dT)12-catalyzed DNA polymerase-gamma reaction was also observed. However, the (rC)n . (dG)12-dependent reverse transcriptase activity was inhibited by (dAfl). The DNA polymerase-beta activity catalyzed by (dA)n . (dT)12 was also inhibited by (dAfl)n. The reported data indicate that (dAfl)n closely resembles (rA)n as a functional template. In contrast, the 2-substituted derivatives, poly(2-methylthioadenylic acid) and poly(2-ethylthioadenylic acid), are not able to discriminate between the reactions catalyzed by different templates. For example, both derivatives inhibit (rA)n . (dT)12- and (rC)n . (dG)12-catalyzed reverse transcriptase reaction to the same extent; though the methylthio derivative is a much better inhibitor than the ethylthio analog. The DNA polymerase-alpha was less sensitive to these inhibitors; whereas the bacterial DNA polymerase (Kornberg enzyme; DNA polymerase I) was completely resistant to the action of all the derivatives used in this study.