Polyamine-induced Z-DNA conformation in plasmids containing (dA-dC)n.(dG-dT)n inserts and increased binding of lupus autoantibodies to the Z-DNA form of plasmids.
Blocks of potential Z-DNA-forming (dA-dC)n.(dG-dT)n sequences are ubiquitous in eukaryotic genomes. We examined whether naturally occurring polyamines, putrescine, spermidine and spermine, could provoke the Z-DNA conformation in plasmids pDHf2 and pDHf14 with 23 and 60 bp inserts respectively of (dA-dC)n.(dG-dT)n sequences using an e.l.i.s.a. Spermidine and spermine could provoke Z-DNA conformation in these plasmids, but putrescine was ineffective. For pDHf2 and pDHf14, the concentration of spermidine at the midpoint of B-DNA to Z-DNA transition was 25 microM, whereas that of spermine was 16 microM. Polyamine structural specificity was evident in the ability of spermidine homologues to induce Z-DNA. Inorganic cations, Co(NH3)6(3+) and Ru(NH3)6(3+), were ineffective. Our experiments also showed increased binding of anti-DNA autoantibodies from lupus patients as well as autoimmune MRL-lpr/lpr mice to pDHf2 and pDHf14 in the presence of polyamines. These data demonstrate that small blocks of (dA-dC)n.(dG-dT)n sequences could assume the Z-DNA conformation in the presence of natural polyamines. Increased concentrations of polyamines in the sera of lupus patients might facilitate immune complex-formation involving circulating DNA and anti-Z-DNA antibodies.
Thomas
T J
TJ
Clinical Research Center, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick 08903.
Thomas
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D000818:Animals; D000974:Antibodies, Antinuclear / Q000276:immunology*; D001666:Binding Sites, Antibody; D015317:Biogenic Polyamines / Q000502:physiology*; D002417:Cattle; D004247:DNA / Q000737:chemistry* / Q000276:immunology; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D051379:Mice; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D013095:Spermidine / Q000502:physiology
D000974:Antibodies, Antinuclear; D015317:Biogenic Polyamines; D009838:Oligodeoxyribonucleotides; D004247:DNA; D013095:Spermidine