Polydeoxyguanine Motifs in a 12-mer Phosphorothioate Oligodeoxynucleotide Augment Binding to the v3 Loop of HIV-1 gpl20 and Potency of HIV-1 Inhibition Independently of G-Tetrad Formation

Abstract

Phosphorothioate oligodeoxynucleotides belong to a class of polyanions that bind to the third variable domain (v3) of HIV-1 gp120 and inhibit infectivity of a wide variety of HIV-1 isolates. This potent v3 binding of phosphorothioate oligodeoxynucleotides, which is relatively independent of the nucleotide sequence of the oligodeoxynucleotides, decreases with chain length (below 18-mers) and is low for 8-mers. However, recent studies have observed a nucleotide sequence-dependent augmentation of phosphorothioate oligodeoxynucleotide binding to v3 for 8-mers that contain the S-dG4 motif (e.g., SdT2G4T2) and have suggested that formation of quadruple helical tetraplexes (G-tetrads) is associated with the acquisition of v3 binding ability by small phosphorothioate oligodeoxynucleotides. In the current study, a series of SdG4-containing oligodeoxynucleotides were synthesized with varying tandem length (including the 8-mer SdT2G4T2, the 12-mer SdG4T4G4, and the 28-mer SdG4(T4G4)3) and compared with phosphorothioate oligodeoxynucleotides (with similar lengths or related sequences) for (1) their inhibition of the binding of mAb 9284, which binds to the N-terminal portion of the v3 loop, (2) the values of Kc when these compounds are used as competitors of the rgp120-binding of an alkylating phosphodiester oligodeoxynucleotide probe, and (3) inhibition of HIV-1 infectivity in a cell-cell transmission model. The presence of S-dG4 motifs and the number of tandem motifs augmented v3 binding and anti-HIV-1 infectivity for small (8-mer or 12-mer oligodeoxynucleotides) but did not significantly augment the potency of 28-mers. Whereas tetraplex formation of SdT2G4T2 may contribute to its v3 binding, the 12-mer SdG4T4G4 does not migrate as the tetraplex on nonreducing gels, suggesting that S-dG4 motifs may augment anti-HIV activity by multiple mechanisms.

Specific inhibition of human telomerase activity by transfection reagent,FuGENE6‐antisense phosphorothioate oligonucleotide complex inHeLa cells

“…Presumably, addition bases of the longer S-ODNs offer more potential for non-specific contacts in the yield stronger intramolecular secondary structure, thereby reducing the likelihood of binding the telomerase target. It is known that the phosphorothioate oligonucleotides blocked the proliferation HIV-1 in infected cells in a nonsequence specific manner [43], probably the inhibition of reverse transcriptase [44,45] and/or the viral entry process [46,47]. Our previous study of the anti-HIV activities of antisense oligonucleotides indicated that a phosphorothioate oligonucleotide targeted to the HIV-1 gag gene was inhibitory, and the sense and the random sequence oligomers were also able to protect against HIV-1 induced CPE, but their anti-HIV-1 activities were weaker than that of the antisense phosphorothioate oligonucleotide (S-ODN-gag-AUG) [48].…”

Anti-Human Immunodeficiency Virus Type 1 Activity of R-95288, a Phosphodiester Hexadeoxyribonucleotide Modified by Dibenzyloxybenzyl and Hydroxyethyl Residues at the 5′- and 3′-Ends

“…However, other mechanisms have also been found including the inhibition of virus integrase activity and of interaction of envelope glycoprotein gp120 with its receptor CD4 (Stein et al, 1991(Stein et al, , 1993Ojwang et al, 1995;Wyatt et al, 1994;Buckheit et al, 1994). For example, oligonucleotides with phosphorothioate linkages, a cytidine homopolymer (28-mer), S-dC28 (Stein et al, 1991(Stein et al, , 1993 and a guanine-rich oligonucleotide (8-mer), ISIS5320 (Wyatt etal., 1994;Lederman et al, 1996), were found to inhibit HIV-1 replication by interaction with CD4 and/or the V3loop of gp120. Moreover, guanine-rich oligonucleotides with only phosphodiester linkages were also found to exhibit anti-HIV-1 activity by interference…”

Inhibition of Human Immunodeficiency Virus Type 1 Activity In Vitro by a New Self-Stabilized Oligonucleotide with Guanosine-Thymidine Quadruplex Motifs

“…However, phosphorothioate oligonucleotides hybridize more weakly with the complementary nucleic acids than unmodified oligonucleotides and are eventually degraded, primarily from the 3Ј end. Antisense phosphorothioate oligonucleotides have also been shown to block the proliferation of HIV-1 in acutely infected cells in a non-sequence-specific manner (24), probably by inhibition of RT (4,25) and/or the viral entry process (21,36). On the other hand, Majumdar et al have shown that the homocytidine phosphorothioate oligonucleotide SdC28 is a potent inhibitor of HIV-1 RT with respect to template primer binding (23).…”