INHIBITION OF HIV-1 REVERSE-TRANSCRIPTASE BY DEFINED TEMPLATE PRIMER DNA OLIGONUCLEOTIDES - EFFECT OF TEMPLATE LENGTH AND BINDING CHARACTERISTICS

The interaction of partially double stranded DNA oligonucleotides with HIV-1 RT was studied by investigating their ability to inhibit the ho mopolymeric poly(rC) directed (dG) synthesis reaction. A 20/18mer olig onucleotide, with a sequence based on the Lys3-tRNA primer region, sho wed stronger inhibition of the homopolymeric RT reaction than a G/C ri ch oligonucleotide series lacking or possessing a hairpin moiety. Inte raction of the enzyme with the G/C rich oligonucleotides as determined by IC50 measurements, was insensitive to the extent of the unpaired t emplate region at the 3' or 5' position. Addition of a hairpin moiety, composed of four thymidine bases, onto ( /C rich oligonucleotides inc rease their inhibitory potency (at least six times) and shifted the mo de of inhibition of RT to competitive with respect to poly (rC).(dG), which was otherwise mixed (competitive/noncompetitive) for the linear G/C rich and 20/18mer oligonucleotides. The results indicate that inte raction of the enzyme with the primer/template stem, but not with the unpaired template region, is an important step in complex formation.