(2'-5')PPP3'DA(P3'DA)(N') A STRUCTURAL MODIFICATION OF (2'-5')PPPA(PA)(N): ENZYMATIC SYNTHESIS, CHARACTERIZATION, AND INHIBITION OF CELLULAR TRANSFORMATION IN EPSTEIN-BARR VIRUS-INFECTED LYMPHOCYTES.

摘要

Interferons are proteins which are synthesized in vertebrate cells in response to viral infection. Other stimuli such as synthetic polynucleotides also induce the synthesis of interferons. Interferon is secreted from infected cells and causes the induction of a dsRNA dependent protein kinase, a (2'-5')oligo(adenylate) synthetase, and possibly a 2',5'-phosphodiesterase. These enzymes regulate cellular protein synthesis. (2'-5')-Oligo(adenylate) synthetase converts ATP into a series of oligoadenylates, (2'-5')pppA(pA)(,n), which are characterized by the unique 2',5'-phosphodiester bond. The (2'-5')pppA(pA)(,n) synthesized activates a (2'-5')oligoadenylate dependent latent endoribonuclease (RNAse L) whose action inhibits translation via degradation of natural and viral RNA. 2',5'-Phosphodiesterase rapidly degrades (2'-5')pppA(pA)(,n). The (2'-5')pppA(pA)(,n) system is one of the putative antiviral systems mediated by interferon.;The cordycepin analog of (2'-5')pppA(pA)(,n), (2'-5')-ppp3'dA(p3'dA)(,n), was synthesized enzymatically from rabbit reticulocyte lysate (RRL) (2'-5')oligo(adenylate) synthetase and 3'dATP. The structure of the cordycepin analog, (2'-5')ppp3'dA(p3'dA)(,n), was determined by enzymatic digestion of putative (2'-5')ppp3'dA(p3'dA)(,n) followed by chromatography and comparison to chemically synthesized material. The results show that the 3'-hydroxyl on the ribosyl moiety of ATP is not essential for synthesis of (2'-5')oligonucleotides. RNAse L appears to be activated by (2'-5')ppp3'dA(p3'dA)(,n); addition of the cordycepin analog to RRL results in substantial inhibition of translation. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of school) UMI;To further characterize the (2'-5')pppA(pA)(,n) system the substrate specificities of the (2'-5')oligo(adenylate) synthetase, RNAse L, and the 2',5'-phosphodiesterase were studied. The ability of the (2'-5')oligoadenylates and the structurally modified (2'-5')oligoadenylates to replace interferon as an antiviral agent was also investigated.