Inhibitory Binding of Adenosine Diphosphoribosyl Transferase to the DNA PrimerSite of Reverse Transcriptase Templates

摘要

Purified adenosine diphosphoribose transferase protein binds to RNA-DNA hybridtemplates of reverse transcriptase at the DNA primer site and inhibits RT activity of HIV and MMu RTs. This action is prevented by auto-poly-ADP-ribosylation of the transferase but is reinduced by inhibitory ligands of the enzyme. ADPRT is a highly abundant non-histone nuclear protein of higher eukaryotes and there is convincing evidence that the poly(ADP-ribose) synthesizing function of this protein represents only a few percent of its molecular activity in intact cells. This is in agreement with the magnitude of the DNA-independent rates of oligo (ADP-ribose) synthesis which can be readily determined even in the 56 kDa polypeptide fragment of ADPRT that has no DNA recognition sites.