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Results for “POLYNUCLEOTIDES”

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At least 1,189 records · Page 66Linked to original sources
PubMed1998

Mitogenic synthetic polynucleotides suppress the antibody response to a bacterial polysaccharide.

Unmethylated bacterial DNA containing a high frequency of the CpG motif, is mitogenic and induces T-cell independent, murine B-cell proliferation. These stimulatory effects are also induced by synthetic oligonucleotides that contain one or more unmethylated CpG dinucleotides (CpG oligo). Such mitogenicity is not seen with highly methylated vertebrate DNA, which has a lower prevalence of the CpG motif than bacterial DNA. Due to their stimulatory effects, CpG oligo have been proposed for use as vaccine adjuvants. In order to determine if a synthetic CpG oligo that was stimulatory for B-cell proliferation could augment the murine antibody response to protective bacterial polysaccharide epitopes (Pseudomonas aeruginosa LPS-O polysaccharide side chain; high-molecular-weight polysaccharide or high-MW PS), BALB/c mice were injected with mitogenic doses of CpG oligo simultaneously with high-MW PS, and antibody titers were measured by ELISA weekly for 4 weeks. Controls received PBS, a nonstimulatory control oligo plus PS, CpG alone, or PS alone. Despite evidence of B-cell mitogenicity and an increase in total IgM in CpG oligo-treated mice, CpG oligo treatment plus PS significantly decreased the high-MW PS antibody response compared to PS alone. The blunting of the anti-PS antibody response could be eliminated by vaccinating the animals with PS prior to CpG oligo. We conclude that despite in vitro and in vivo evidence of B-cell proliferation, this CpG oligo reduces PS-specific antibody responses in an animal model when given simultaneously with a bacterial polysaccharide. Based on results in this model, oligonucleotides containing stimulatory unmethylated CpG dinucleotides may not be useful adjuvants when given simultaneously with bacterial PS vaccines.

Adjuvants, Immunologic↗
PubMed1995

Recombinant human replication protein A binds to polynucleotides with low cooperativity.

Replication protein A (RPA) is a multisubunit single-stranded DNA-binding protein that is involved in multiple aspects of cellular DNA metabolism. We have determined quantitative estimates of the binding parameters of human replication protein A (hRPA) from equilibrium binding isotherms. The intrinsic binding constant (K) and cooperativity parameter (omega) were determined from analysis of changes in the intrinsic fluorescence of hRPA that occurred upon binding single-stranded DNA homopolynucleotides. The cooperativity of hRPA binding to both poly(dT) and poly(dA) was found to be low (omega = 10-20) at all NaCl concentrations examined (0.3-2 M). In contrast, the apparent binding affinity (K omega) of RPA decreased significantly with increasing salt concentration, such that log [NaCl]/log K omega was -2.8 for poly(dT) and -4.8 for poly(dA). We conclude that the salt dependent decrease in binding affinity resulted from changes in the intrinsic binding constant (K). These data suggest that the interaction of hRPA with single-stranded DNA involves significant electrostatic interactions, similar to other single-stranded DNA-binding proteins. The apparent binding affinity (K omega) of RPA was higher for poly(dT) than for poly(dA); extrapolation of our data indicated that the apparent binding affinity at 0.2 M NaCl was 1.6 x 10(10) M-1 for poly(dT) and 1.1 x 10(9) M-1 for poly(dA).

DNA, Single-Stranded↗
PubMed1989

Interactions of the dimethyldiazaperopyrenium dication with nucleic acids. 2. Binding to double-stranded polynucleotides.

The interactions of dimethyldiazaperopyrenium dication (1) with DNA have been studied by spectroscopic methods: absorption, static and dynamic fluorescence, and linear dichroism. 1 binds strongly to DNA at 250 mM NaCl, with a higher affinity for G-C pairs as compared to A-T pairs. The dye fluorescence is enhanced when it is bound to A-T pairs, whereas the emission is quenched in the vicinity of G-C pairs. Evidence for intercalation has been obtained via energy transfer and linear dichroism measurements.

Base Composition↗